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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Kernel-based Virtual Machine driver for Linux
  *
  * This module enables machines with Intel VT-x extensions to run virtual
  * machines without emulation or binary translation.
  *
  * Copyright (C) 2006 Qumranet, Inc.
  * Copyright 2010 Red Hat, Inc. and/or its affiliates.
  *
  * Authors:
  *   Avi Kivity   <avi@qumranet.com>
  *   Yaniv Kamay  <yaniv@qumranet.com>
  */
 
 #include <kvm/iodev.h>
 
 #include <linux/kvm_host.h>
 #include <linux/kvm.h>
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/percpu.h>
 #include <linux/mm.h>
 #include <linux/miscdevice.h>
 #include <linux/vmalloc.h>
 #include <linux/reboot.h>
 #include <linux/debugfs.h>
 #include <linux/highmem.h>
 #include <linux/file.h>
 #include <linux/syscore_ops.h>
 #include <linux/cpu.h>
 #include <linux/sched/signal.h>
 #include <linux/sched/mm.h>
 #include <linux/sched/stat.h>
 #include <linux/cpumask.h>
 #include <linux/smp.h>
 #include <linux/anon_inodes.h>
 #include <linux/profile.h>
 #include <linux/kvm_para.h>
 #include <linux/pagemap.h>
 #include <linux/mman.h>
 #include <linux/swap.h>
 #include <linux/bitops.h>
 #include <linux/spinlock.h>
 #include <linux/compat.h>
 #include <linux/srcu.h>
 #include <linux/hugetlb.h>
 #include <linux/slab.h>
 #include <linux/sort.h>
 #include <linux/bsearch.h>
 #include <linux/io.h>
 #include <linux/lockdep.h>
 #include <linux/kthread.h>
 #include <linux/suspend.h>
 
 #include <asm/processor.h>
 #include <asm/ioctl.h>
 #include <linux/uaccess.h>
 
 #include "coalesced_mmio.h"
 #include "async_pf.h"
 #include "kvm_mm.h"
 #include "vfio.h"
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/kvm.h>
 
 #include <linux/kvm_dirty_ring.h>
 
 /* Worst case buffer size needed for holding an integer. */
 #define ITOA_MAX_LEN 12
 
 MODULE_AUTHOR("Qumranet");
 MODULE_LICENSE("GPL");
 
 /* Architectures should define their poll value according to the halt latency */
 unsigned int halt_poll_ns = KVM_HALT_POLL_NS_DEFAULT;
 module_param(halt_poll_ns, uint, 0644);
 EXPORT_SYMBOL_GPL(halt_poll_ns);
 
 /* Default doubles per-vcpu halt_poll_ns. */
 unsigned int halt_poll_ns_grow = 2;
 module_param(halt_poll_ns_grow, uint, 0644);
 EXPORT_SYMBOL_GPL(halt_poll_ns_grow);
 
 /* The start value to grow halt_poll_ns from */
 unsigned int halt_poll_ns_grow_start = 10000; /* 10us */
 module_param(halt_poll_ns_grow_start, uint, 0644);
 EXPORT_SYMBOL_GPL(halt_poll_ns_grow_start);
 
 /* Default resets per-vcpu halt_poll_ns . */
 unsigned int halt_poll_ns_shrink;
 module_param(halt_poll_ns_shrink, uint, 0644);
 EXPORT_SYMBOL_GPL(halt_poll_ns_shrink);
 
 /*
  * Ordering of locks:
  *
  *  kvm->lock --> kvm->slots_lock --> kvm->irq_lock
  */
 
 DEFINE_MUTEX(kvm_lock);
 static DEFINE_RAW_SPINLOCK(kvm_count_lock);
 LIST_HEAD(vm_list);
 
 static cpumask_var_t cpus_hardware_enabled;
 static int kvm_usage_count;
 static atomic_t hardware_enable_failed;
 
 static struct kmem_cache *kvm_vcpu_cache;
 
 static __read_mostly struct preempt_ops kvm_preempt_ops;
 static DEFINE_PER_CPU(struct kvm_vcpu *, kvm_running_vcpu);
 
 struct dentry *kvm_debugfs_dir;
 EXPORT_SYMBOL_GPL(kvm_debugfs_dir);
 
 static const struct file_operations stat_fops_per_vm;
 
 static struct file_operations kvm_chardev_ops;
 
 static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
                unsigned long arg);
 #ifdef CONFIG_KVM_COMPAT
 static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl,
                   unsigned long arg);
 #define KVM_COMPAT(c)   .compat_ioctl   = (c)
 #else
 /*
  * For architectures that don't implement a compat infrastructure,
  * adopt a double line of defense:
  * - Prevent a compat task from opening /dev/kvm
  * - If the open has been done by a 64bit task, and the KVM fd
  *   passed to a compat task, let the ioctls fail.
  */
 static long kvm_no_compat_ioctl(struct file *file, unsigned int ioctl,
                 unsigned long arg) { return -EINVAL; }
 
 static int kvm_no_compat_open(struct inode *inode, struct file *file)
 {
     return is_compat_task() ? -ENODEV : 0;
 }
 #define KVM_COMPAT(c)   .compat_ioctl   = kvm_no_compat_ioctl,  \
             .open       = kvm_no_compat_open
 #endif
 static int hardware_enable_all(void);
 static void hardware_disable_all(void);
 
 static void kvm_io_bus_destroy(struct kvm_io_bus *bus);
 
 __visible bool kvm_rebooting;
 EXPORT_SYMBOL_GPL(kvm_rebooting);
 
 #define KVM_EVENT_CREATE_VM 0
 #define KVM_EVENT_DESTROY_VM 1
 static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm);
 static unsigned long long kvm_createvm_count;
 static unsigned long long kvm_active_vms;
 
 static DEFINE_PER_CPU(cpumask_var_t, cpu_kick_mask);
 
 __weak void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,
                            unsigned long start, unsigned long end)
 {
 }
 
 __weak void kvm_arch_guest_memory_reclaimed(struct kvm *kvm)
 {
 }
 
 bool kvm_is_zone_device_page(struct page *page)
 {
     /*
      * The metadata used by is_zone_device_page() to determine whether or
      * not a page is ZONE_DEVICE is guaranteed to be valid if and only if
      * the device has been pinned, e.g. by get_user_pages().  WARN if the
      * page_count() is zero to help detect bad usage of this helper.
      */
     if (WARN_ON_ONCE(!page_count(page)))
         return false;
 
     return is_zone_device_page(page);
 }
 
 /*
  * Returns a 'struct page' if the pfn is "valid" and backed by a refcounted
  * page, NULL otherwise.  Note, the list of refcounted PG_reserved page types
  * is likely incomplete, it has been compiled purely through people wanting to
  * back guest with a certain type of memory and encountering issues.
  */
 struct page *kvm_pfn_to_refcounted_page(kvm_pfn_t pfn)
 {
     struct page *page;
 
     if (!pfn_valid(pfn))
         return NULL;
 
     page = pfn_to_page(pfn);
     if (!PageReserved(page))
         return page;
 
     /* The ZERO_PAGE(s) is marked PG_reserved, but is refcounted. */
     if (is_zero_pfn(pfn))
         return page;
 
     /*
      * ZONE_DEVICE pages currently set PG_reserved, but from a refcounting
      * perspective they are "normal" pages, albeit with slightly different
      * usage rules.
      */
     if (kvm_is_zone_device_page(page))
         return page;
 
     return NULL;
 }
 
 /*
  * Switches to specified vcpu, until a matching vcpu_put()
  */
 void vcpu_load(struct kvm_vcpu *vcpu)
 {
     int cpu = get_cpu();
 
     __this_cpu_write(kvm_running_vcpu, vcpu);
     preempt_notifier_register(&vcpu->preempt_notifier);
     kvm_arch_vcpu_load(vcpu, cpu);
     put_cpu();
 }
 EXPORT_SYMBOL_GPL(vcpu_load);
 
 void vcpu_put(struct kvm_vcpu *vcpu)
 {
     preempt_disable();
     kvm_arch_vcpu_put(vcpu);
     preempt_notifier_unregister(&vcpu->preempt_notifier);
     __this_cpu_write(kvm_running_vcpu, NULL);
     preempt_enable();
 }
 EXPORT_SYMBOL_GPL(vcpu_put);
 
 /* TODO: merge with kvm_arch_vcpu_should_kick */
 static bool kvm_request_needs_ipi(struct kvm_vcpu *vcpu, unsigned req)
 {
     int mode = kvm_vcpu_exiting_guest_mode(vcpu);
 
     /*
      * We need to wait for the VCPU to reenable interrupts and get out of
      * READING_SHADOW_PAGE_TABLES mode.
      */
     if (req & KVM_REQUEST_WAIT)
         return mode != OUTSIDE_GUEST_MODE;
 
     /*
      * Need to kick a running VCPU, but otherwise there is nothing to do.
      */
     return mode == IN_GUEST_MODE;
 }
 
 static void ack_kick(void *_completed)
 {
 }
 
 static inline bool kvm_kick_many_cpus(struct cpumask *cpus, bool wait)
 {
     if (cpumask_empty(cpus))
         return false;
 
     smp_call_function_many(cpus, ack_kick, NULL, wait);
     return true;
 }
 
 static void kvm_make_vcpu_request(struct kvm_vcpu *vcpu, unsigned int req,
                   struct cpumask *tmp, int current_cpu)
 {
     int cpu;
 
     if (likely(!(req & KVM_REQUEST_NO_ACTION)))
         __kvm_make_request(req, vcpu);
 
     if (!(req & KVM_REQUEST_NO_WAKEUP) && kvm_vcpu_wake_up(vcpu))
         return;
 
     /*
      * Note, the vCPU could get migrated to a different pCPU at any point
      * after kvm_request_needs_ipi(), which could result in sending an IPI
      * to the previous pCPU.  But, that's OK because the purpose of the IPI
      * is to ensure the vCPU returns to OUTSIDE_GUEST_MODE, which is
      * satisfied if the vCPU migrates. Entering READING_SHADOW_PAGE_TABLES
      * after this point is also OK, as the requirement is only that KVM wait
      * for vCPUs that were reading SPTEs _before_ any changes were
      * finalized. See kvm_vcpu_kick() for more details on handling requests.
      */
     if (kvm_request_needs_ipi(vcpu, req)) {
         cpu = READ_ONCE(vcpu->cpu);
         if (cpu != -1 && cpu != current_cpu)
             __cpumask_set_cpu(cpu, tmp);
     }
 }
 
 bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
                  unsigned long *vcpu_bitmap)
 {
     struct kvm_vcpu *vcpu;
     struct cpumask *cpus;
     int i, me;
     bool called;
 
     me = get_cpu();
 
     cpus = this_cpu_cpumask_var_ptr(cpu_kick_mask);
     cpumask_clear(cpus);
 
     for_each_set_bit(i, vcpu_bitmap, KVM_MAX_VCPUS) {
         vcpu = kvm_get_vcpu(kvm, i);
         if (!vcpu)
             continue;
         kvm_make_vcpu_request(vcpu, req, cpus, me);
     }
 
     called = kvm_kick_many_cpus(cpus, !!(req & KVM_REQUEST_WAIT));
     put_cpu();
 
     return called;
 }
 
 bool kvm_make_all_cpus_request_except(struct kvm *kvm, unsigned int req,
                       struct kvm_vcpu *except)
 {
     struct kvm_vcpu *vcpu;
     struct cpumask *cpus;
     unsigned long i;
     bool called;
     int me;
 
     me = get_cpu();
 
     cpus = this_cpu_cpumask_var_ptr(cpu_kick_mask);
     cpumask_clear(cpus);
 
     kvm_for_each_vcpu(i, vcpu, kvm) {
         if (vcpu == except)
             continue;
         kvm_make_vcpu_request(vcpu, req, cpus, me);
     }
 
     called = kvm_kick_many_cpus(cpus, !!(req & KVM_REQUEST_WAIT));
     put_cpu();
 
     return called;
 }
 
 bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req)
 {
     return kvm_make_all_cpus_request_except(kvm, req, NULL);
 }
 EXPORT_SYMBOL_GPL(kvm_make_all_cpus_request);
 
 #ifndef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL
 void kvm_flush_remote_tlbs(struct kvm *kvm)
 {
     ++kvm->stat.generic.remote_tlb_flush_requests;
 
     /*
      * We want to publish modifications to the page tables before reading
      * mode. Pairs with a memory barrier in arch-specific code.
      * - x86: smp_mb__after_srcu_read_unlock in vcpu_enter_guest
      * and smp_mb in walk_shadow_page_lockless_begin/end.
      * - powerpc: smp_mb in kvmppc_prepare_to_enter.
      *
      * There is already an smp_mb__after_atomic() before
      * kvm_make_all_cpus_request() reads vcpu->mode. We reuse that
      * barrier here.
      */
     if (!kvm_arch_flush_remote_tlb(kvm)
         || kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH))
         ++kvm->stat.generic.remote_tlb_flush;
 }
 EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs);
 #endif
 
 static void kvm_flush_shadow_all(struct kvm *kvm)
 {
     kvm_arch_flush_shadow_all(kvm);
     kvm_arch_guest_memory_reclaimed(kvm);
 }
 
 #ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
 static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
                            gfp_t gfp_flags)
 {
     gfp_flags |= mc->gfp_zero;
 
     if (mc->kmem_cache)
         return kmem_cache_alloc(mc->kmem_cache, gfp_flags);
     else
         return (void *)__get_free_page(gfp_flags);
 }
 
 int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int capacity, int min)
 {
     gfp_t gfp = mc->gfp_custom ? mc->gfp_custom : GFP_KERNEL_ACCOUNT;
     void *obj;
 
     if (mc->nobjs >= min)
         return 0;
 
     if (unlikely(!mc->objects)) {
         if (WARN_ON_ONCE(!capacity))
             return -EIO;
 
         mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
         if (!mc->objects)
             return -ENOMEM;
 
         mc->capacity = capacity;
     }
 
     /* It is illegal to request a different capacity across topups. */
     if (WARN_ON_ONCE(mc->capacity != capacity))
         return -EIO;
 
     while (mc->nobjs < mc->capacity) {
         obj = mmu_memory_cache_alloc_obj(mc, gfp);
         if (!obj)
             return mc->nobjs >= min ? 0 : -ENOMEM;
         mc->objects[mc->nobjs++] = obj;
     }
     return 0;
 }
 
 int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
 {
     return __kvm_mmu_topup_memory_cache(mc, KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE, min);
 }
 
 int kvm_mmu_memory_cache_nr_free_objects(struct kvm_mmu_memory_cache *mc)
 {
     return mc->nobjs;
 }
 
 void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
 {
     while (mc->nobjs) {
         if (mc->kmem_cache)
             kmem_cache_free(mc->kmem_cache, mc->objects[--mc->nobjs]);
         else
             free_page((unsigned long)mc->objects[--mc->nobjs]);
     }
 
     kvfree(mc->objects);
 
     mc->objects = NULL;
     mc->capacity = 0;
 }
 
 void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
 {
     void *p;
 
     if (WARN_ON(!mc->nobjs))
         p = mmu_memory_cache_alloc_obj(mc, GFP_ATOMIC | __GFP_ACCOUNT);
     else
         p = mc->objects[--mc->nobjs];
     BUG_ON(!p);
     return p;
 }
 #endif
 
 static void kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
 {
     mutex_init(&vcpu->mutex);
     vcpu->cpu = -1;
     vcpu->kvm = kvm;
     vcpu->vcpu_id = id;
     vcpu->pid = NULL;
 #ifndef __KVM_HAVE_ARCH_WQP
     rcuwait_init(&vcpu->wait);
 #endif
     kvm_async_pf_vcpu_init(vcpu);
 
     kvm_vcpu_set_in_spin_loop(vcpu, false);
     kvm_vcpu_set_dy_eligible(vcpu, false);
     vcpu->preempted = false;
     vcpu->ready = false;
     preempt_notifier_init(&vcpu->preempt_notifier, &kvm_preempt_ops);
     vcpu->last_used_slot = NULL;
 
     /* Fill the stats id string for the vcpu */
     snprintf(vcpu->stats_id, sizeof(vcpu->stats_id), "kvm-%d/vcpu-%d",
          task_pid_nr(current), id);
 }
 
 static void kvm_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
     kvm_arch_vcpu_destroy(vcpu);
     kvm_dirty_ring_free(&vcpu->dirty_ring);
 
     /*
      * No need for rcu_read_lock as VCPU_RUN is the only place that changes
      * the vcpu->pid pointer, and at destruction time all file descriptors
      * are already gone.
      */
     put_pid(rcu_dereference_protected(vcpu->pid, 1));
 
     free_page((unsigned long)vcpu->run);
     kmem_cache_free(kvm_vcpu_cache, vcpu);
 }
 
 void kvm_destroy_vcpus(struct kvm *kvm)
 {
     unsigned long i;
     struct kvm_vcpu *vcpu;
 
     kvm_for_each_vcpu(i, vcpu, kvm) {
         kvm_vcpu_destroy(vcpu);
         xa_erase(&kvm->vcpu_array, i);
     }
 
     atomic_set(&kvm->online_vcpus, 0);
 }
 EXPORT_SYMBOL_GPL(kvm_destroy_vcpus);
 
 #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
 static inline struct kvm *mmu_notifier_to_kvm(struct mmu_notifier *mn)
 {
     return container_of(mn, struct kvm, mmu_notifier);
 }
 
 static void kvm_mmu_notifier_invalidate_range(struct mmu_notifier *mn,
                           struct mm_struct *mm,
                           unsigned long start, unsigned long end)
 {
     struct kvm *kvm = mmu_notifier_to_kvm(mn);
     int idx;
 
     idx = srcu_read_lock(&kvm->srcu);
     kvm_arch_mmu_notifier_invalidate_range(kvm, start, end);
     srcu_read_unlock(&kvm->srcu, idx);
 }
 
 typedef bool (*hva_handler_t)(struct kvm *kvm, struct kvm_gfn_range *range);
 
 typedef void (*on_lock_fn_t)(struct kvm *kvm, unsigned long start,
                  unsigned long end);
 
 typedef void (*on_unlock_fn_t)(struct kvm *kvm);
 
 struct kvm_hva_range {
     unsigned long start;
     unsigned long end;
     pte_t pte;
     hva_handler_t handler;
     on_lock_fn_t on_lock;
     on_unlock_fn_t on_unlock;
     bool flush_on_ret;
     bool may_block;
 };
 
 /*
  * Use a dedicated stub instead of NULL to indicate that there is no callback
  * function/handler.  The compiler technically can't guarantee that a real
  * function will have a non-zero address, and so it will generate code to
  * check for !NULL, whereas comparing against a stub will be elided at compile
  * time (unless the compiler is getting long in the tooth, e.g. gcc 4.9).
  */
 static void kvm_null_fn(void)
 {
 
 }
 #define IS_KVM_NULL_FN(fn) ((fn) == (void *)kvm_null_fn)
 
 /* Iterate over each memslot intersecting [start, last] (inclusive) range */
 #define kvm_for_each_memslot_in_hva_range(node, slots, start, last)      \
     for (node = interval_tree_iter_first(&slots->hva_tree, start, last); \
          node;                               \
          node = interval_tree_iter_next(node, start, last))      \
 
 static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
                           const struct kvm_hva_range *range)
 {
     bool ret = false, locked = false;
     struct kvm_gfn_range gfn_range;
     struct kvm_memory_slot *slot;
     struct kvm_memslots *slots;
     int i, idx;
 
     if (WARN_ON_ONCE(range->end <= range->start))
         return 0;
 
     /* A null handler is allowed if and only if on_lock() is provided. */
     if (WARN_ON_ONCE(IS_KVM_NULL_FN(range->on_lock) &&
              IS_KVM_NULL_FN(range->handler)))
         return 0;
 
     idx = srcu_read_lock(&kvm->srcu);
 
     for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
         struct interval_tree_node *node;
 
         slots = __kvm_memslots(kvm, i);
         kvm_for_each_memslot_in_hva_range(node, slots,
                           range->start, range->end - 1) {
             unsigned long hva_start, hva_end;
 
             slot = container_of(node, struct kvm_memory_slot, hva_node[slots->node_idx]);
             hva_start = max(range->start, slot->userspace_addr);
             hva_end = min(range->end, slot->userspace_addr +
                           (slot->npages << PAGE_SHIFT));
 
             /*
              * To optimize for the likely case where the address
              * range is covered by zero or one memslots, don't
              * bother making these conditional (to avoid writes on
              * the second or later invocation of the handler).
              */
             gfn_range.pte = range->pte;
             gfn_range.may_block = range->may_block;
 
             /*
              * {gfn(page) | page intersects with [hva_start, hva_end)} =
              * {gfn_start, gfn_start+1, ..., gfn_end-1}.
              */
             gfn_range.start = hva_to_gfn_memslot(hva_start, slot);
             gfn_range.end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, slot);
             gfn_range.slot = slot;
 
             if (!locked) {
                 locked = true;
                 KVM_MMU_LOCK(kvm);
                 if (!IS_KVM_NULL_FN(range->on_lock))
                     range->on_lock(kvm, range->start, range->end);
                 if (IS_KVM_NULL_FN(range->handler))
                     break;
             }
             ret |= range->handler(kvm, &gfn_range);
         }
     }
 
     if (range->flush_on_ret && ret)
         kvm_flush_remote_tlbs(kvm);
 
     if (locked) {
         KVM_MMU_UNLOCK(kvm);
         if (!IS_KVM_NULL_FN(range->on_unlock))
             range->on_unlock(kvm);
     }
 
     srcu_read_unlock(&kvm->srcu, idx);
 
     /* The notifiers are averse to booleans. :-( */
     return (int)ret;
 }
 
 static __always_inline int kvm_handle_hva_range(struct mmu_notifier *mn,
                         unsigned long start,
                         unsigned long end,
                         pte_t pte,
                         hva_handler_t handler)
 {
     struct kvm *kvm = mmu_notifier_to_kvm(mn);
     const struct kvm_hva_range range = {
         .start      = start,
         .end        = end,
         .pte        = pte,
         .handler    = handler,
         .on_lock    = (void *)kvm_null_fn,
         .on_unlock  = (void *)kvm_null_fn,
         .flush_on_ret   = true,
         .may_block  = false,
     };
 
     return __kvm_handle_hva_range(kvm, &range);
 }
 
 static __always_inline int kvm_handle_hva_range_no_flush(struct mmu_notifier *mn,
                              unsigned long start,
                              unsigned long end,
                              hva_handler_t handler)
 {
     struct kvm *kvm = mmu_notifier_to_kvm(mn);
     const struct kvm_hva_range range = {
         .start      = start,
         .end        = end,
         .pte        = __pte(0),
         .handler    = handler,
         .on_lock    = (void *)kvm_null_fn,
         .on_unlock  = (void *)kvm_null_fn,
         .flush_on_ret   = false,
         .may_block  = false,
     };
 
     return __kvm_handle_hva_range(kvm, &range);
 }
 static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
                     struct mm_struct *mm,
                     unsigned long address,
                     pte_t pte)
 {
     struct kvm *kvm = mmu_notifier_to_kvm(mn);
 
     trace_kvm_set_spte_hva(address);
 
     /*
      * .change_pte() must be surrounded by .invalidate_range_{start,end}().
      * If mmu_invalidate_in_progress is zero, then no in-progress
      * invalidations, including this one, found a relevant memslot at
      * start(); rechecking memslots here is unnecessary.  Note, a false
      * positive (count elevated by a different invalidation) is sub-optimal
      * but functionally ok.
      */
     WARN_ON_ONCE(!READ_ONCE(kvm->mn_active_invalidate_count));
     if (!READ_ONCE(kvm->mmu_invalidate_in_progress))
         return;
 
     kvm_handle_hva_range(mn, address, address + 1, pte, kvm_set_spte_gfn);
 }
 
 void kvm_mmu_invalidate_begin(struct kvm *kvm, unsigned long start,
                   unsigned long end)
 {
     /*
      * The count increase must become visible at unlock time as no
      * spte can be established without taking the mmu_lock and
      * count is also read inside the mmu_lock critical section.
      */
     kvm->mmu_invalidate_in_progress++;
     if (likely(kvm->mmu_invalidate_in_progress == 1)) {
         kvm->mmu_invalidate_range_start = start;
         kvm->mmu_invalidate_range_end = end;
     } else {
         /*
          * Fully tracking multiple concurrent ranges has diminishing
          * returns. Keep things simple and just find the minimal range
          * which includes the current and new ranges. As there won't be
          * enough information to subtract a range after its invalidate
          * completes, any ranges invalidated concurrently will
          * accumulate and persist until all outstanding invalidates
          * complete.
          */
         kvm->mmu_invalidate_range_start =
             min(kvm->mmu_invalidate_range_start, start);
         kvm->mmu_invalidate_range_end =
             max(kvm->mmu_invalidate_range_end, end);
     }
 }
 
 static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
                     const struct mmu_notifier_range *range)
 {
     struct kvm *kvm = mmu_notifier_to_kvm(mn);
     const struct kvm_hva_range hva_range = {
         .start      = range->start,
         .end        = range->end,
         .pte        = __pte(0),
         .handler    = kvm_unmap_gfn_range,
         .on_lock    = kvm_mmu_invalidate_begin,
         .on_unlock  = kvm_arch_guest_memory_reclaimed,
         .flush_on_ret   = true,
         .may_block  = mmu_notifier_range_blockable(range),
     };
 
     trace_kvm_unmap_hva_range(range->start, range->end);
 
     /*
      * Prevent memslot modification between range_start() and range_end()
      * so that conditionally locking provides the same result in both
      * functions.  Without that guarantee, the mmu_invalidate_in_progress
      * adjustments will be imbalanced.
      *
      * Pairs with the decrement in range_end().
      */
     spin_lock(&kvm->mn_invalidate_lock);
     kvm->mn_active_invalidate_count++;
     spin_unlock(&kvm->mn_invalidate_lock);
 
     /*
      * Invalidate pfn caches _before_ invalidating the secondary MMUs, i.e.
      * before acquiring mmu_lock, to avoid holding mmu_lock while acquiring
      * each cache's lock.  There are relatively few caches in existence at
      * any given time, and the caches themselves can check for hva overlap,
      * i.e. don't need to rely on memslot overlap checks for performance.
      * Because this runs without holding mmu_lock, the pfn caches must use
      * mn_active_invalidate_count (see above) instead of
      * mmu_invalidate_in_progress.
      */
     gfn_to_pfn_cache_invalidate_start(kvm, range->start, range->end,
                       hva_range.may_block);
 
     __kvm_handle_hva_range(kvm, &hva_range);
 
     return 0;
 }
 
 void kvm_mmu_invalidate_end(struct kvm *kvm, unsigned long start,
                 unsigned long end)
 {
     /*
      * This sequence increase will notify the kvm page fault that
      * the page that is going to be mapped in the spte could have
      * been freed.
      */
     kvm->mmu_invalidate_seq++;
     smp_wmb();
     /*
      * The above sequence increase must be visible before the
      * below count decrease, which is ensured by the smp_wmb above
      * in conjunction with the smp_rmb in mmu_invalidate_retry().
      */
     kvm->mmu_invalidate_in_progress--;
 }
 
 static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
                     const struct mmu_notifier_range *range)
 {
     struct kvm *kvm = mmu_notifier_to_kvm(mn);
     const struct kvm_hva_range hva_range = {
         .start      = range->start,
         .end        = range->end,
         .pte        = __pte(0),
         .handler    = (void *)kvm_null_fn,
         .on_lock    = kvm_mmu_invalidate_end,
         .on_unlock  = (void *)kvm_null_fn,
         .flush_on_ret   = false,
         .may_block  = mmu_notifier_range_blockable(range),
     };
     bool wake;
 
     __kvm_handle_hva_range(kvm, &hva_range);
 
     /* Pairs with the increment in range_start(). */
     spin_lock(&kvm->mn_invalidate_lock);
     wake = (--kvm->mn_active_invalidate_count == 0);
     spin_unlock(&kvm->mn_invalidate_lock);
 
     /*
      * There can only be one waiter, since the wait happens under
      * slots_lock.
      */
     if (wake)
         rcuwait_wake_up(&kvm->mn_memslots_update_rcuwait);
 
     BUG_ON(kvm->mmu_invalidate_in_progress < 0);
 }
 
 static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
                           struct mm_struct *mm,
                           unsigned long start,
                           unsigned long end)
 {
     trace_kvm_age_hva(start, end);
 
     return kvm_handle_hva_range(mn, start, end, __pte(0), kvm_age_gfn);
 }
 
 static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn,
                     struct mm_struct *mm,
                     unsigned long start,
                     unsigned long end)
 {
     trace_kvm_age_hva(start, end);
 
     /*
      * Even though we do not flush TLB, this will still adversely
      * affect performance on pre-Haswell Intel EPT, where there is
      * no EPT Access Bit to clear so that we have to tear down EPT
      * tables instead. If we find this unacceptable, we can always
      * add a parameter to kvm_age_hva so that it effectively doesn't
      * do anything on clear_young.
      *
      * Also note that currently we never issue secondary TLB flushes
      * from clear_young, leaving this job up to the regular system
      * cadence. If we find this inaccurate, we might come up with a
      * more sophisticated heuristic later.
      */
     return kvm_handle_hva_range_no_flush(mn, start, end, kvm_age_gfn);
 }
 
 static int kvm_mmu_notifier_test_young(struct mmu_notifier *mn,
                        struct mm_struct *mm,
                        unsigned long address)
 {
     trace_kvm_test_age_hva(address);
 
     return kvm_handle_hva_range_no_flush(mn, address, address + 1,
                          kvm_test_age_gfn);
 }
 
 static void kvm_mmu_notifier_release(struct mmu_notifier *mn,
                      struct mm_struct *mm)
 {
     struct kvm *kvm = mmu_notifier_to_kvm(mn);
     int idx;
 
     idx = srcu_read_lock(&kvm->srcu);
     kvm_flush_shadow_all(kvm);
     srcu_read_unlock(&kvm->srcu, idx);
 }
 
 static const struct mmu_notifier_ops kvm_mmu_notifier_ops = {
     .invalidate_range   = kvm_mmu_notifier_invalidate_range,
     .invalidate_range_start = kvm_mmu_notifier_invalidate_range_start,
     .invalidate_range_end   = kvm_mmu_notifier_invalidate_range_end,
     .clear_flush_young  = kvm_mmu_notifier_clear_flush_young,
     .clear_young        = kvm_mmu_notifier_clear_young,
     .test_young     = kvm_mmu_notifier_test_young,
     .change_pte     = kvm_mmu_notifier_change_pte,
     .release        = kvm_mmu_notifier_release,
 };
 
 static int kvm_init_mmu_notifier(struct kvm *kvm)
 {
     kvm->mmu_notifier.ops = &kvm_mmu_notifier_ops;
     return mmu_notifier_register(&kvm->mmu_notifier, current->mm);
 }
 
 #else  /* !(CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER) */
 
 static int kvm_init_mmu_notifier(struct kvm *kvm)
 {
     return 0;
 }
 
 #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
 
 #ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
 static int kvm_pm_notifier_call(struct notifier_block *bl,
                 unsigned long state,
                 void *unused)
 {
     struct kvm *kvm = container_of(bl, struct kvm, pm_notifier);
 
     return kvm_arch_pm_notifier(kvm, state);
 }
 
 static void kvm_init_pm_notifier(struct kvm *kvm)
 {
     kvm->pm_notifier.notifier_call = kvm_pm_notifier_call;
     /* Suspend KVM before we suspend ftrace, RCU, etc. */
     kvm->pm_notifier.priority = INT_MAX;
     register_pm_notifier(&kvm->pm_notifier);
 }
 
 static void kvm_destroy_pm_notifier(struct kvm *kvm)
 {
     unregister_pm_notifier(&kvm->pm_notifier);
 }
 #else /* !CONFIG_HAVE_KVM_PM_NOTIFIER */
 static void kvm_init_pm_notifier(struct kvm *kvm)
 {
 }
 
 static void kvm_destroy_pm_notifier(struct kvm *kvm)
 {
 }
 #endif /* CONFIG_HAVE_KVM_PM_NOTIFIER */
 
 static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot)
 {
     if (!memslot->dirty_bitmap)
         return;
 
     kvfree(memslot->dirty_bitmap);
     memslot->dirty_bitmap = NULL;
 }
 
 /* This does not remove the slot from struct kvm_memslots data structures */
 static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
 {
     kvm_destroy_dirty_bitmap(slot);
 
     kvm_arch_free_memslot(kvm, slot);
 
     kfree(slot);
 }
 
 static void kvm_free_memslots(struct kvm *kvm, struct kvm_memslots *slots)
 {
     struct hlist_node *idnode;
     struct kvm_memory_slot *memslot;
     int bkt;
 
     /*
      * The same memslot objects live in both active and inactive sets,
      * arbitrarily free using index '1' so the second invocation of this
      * function isn't operating over a structure with dangling pointers
      * (even though this function isn't actually touching them).
      */
     if (!slots->node_idx)
         return;
 
     hash_for_each_safe(slots->id_hash, bkt, idnode, memslot, id_node[1])
         kvm_free_memslot(kvm, memslot);
 }
 
 static umode_t kvm_stats_debugfs_mode(const struct _kvm_stats_desc *pdesc)
 {
     switch (pdesc->desc.flags & KVM_STATS_TYPE_MASK) {
     case KVM_STATS_TYPE_INSTANT:
         return 0444;
     case KVM_STATS_TYPE_CUMULATIVE:
     case KVM_STATS_TYPE_PEAK:
     default:
         return 0644;
     }
 }
 
 
 static void kvm_destroy_vm_debugfs(struct kvm *kvm)
 {
     int i;
     int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc +
                       kvm_vcpu_stats_header.num_desc;
 
     if (IS_ERR(kvm->debugfs_dentry))
         return;
 
     debugfs_remove_recursive(kvm->debugfs_dentry);
 
     if (kvm->debugfs_stat_data) {
         for (i = 0; i < kvm_debugfs_num_entries; i++)
             kfree(kvm->debugfs_stat_data[i]);
         kfree(kvm->debugfs_stat_data);
     }
 }
 
 static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname)
 {
     static DEFINE_MUTEX(kvm_debugfs_lock);
     struct dentry *dent;
     char dir_name[ITOA_MAX_LEN * 2];
     struct kvm_stat_data *stat_data;
     const struct _kvm_stats_desc *pdesc;
     int i, ret = -ENOMEM;
     int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc +
                       kvm_vcpu_stats_header.num_desc;
 
     if (!debugfs_initialized())
         return 0;
 
     snprintf(dir_name, sizeof(dir_name), "%d-%s", task_pid_nr(current), fdname);
     mutex_lock(&kvm_debugfs_lock);
     dent = debugfs_lookup(dir_name, kvm_debugfs_dir);
     if (dent) {
         pr_warn_ratelimited("KVM: debugfs: duplicate directory %s\n", dir_name);
         dput(dent);
         mutex_unlock(&kvm_debugfs_lock);
         return 0;
     }
     dent = debugfs_create_dir(dir_name, kvm_debugfs_dir);
     mutex_unlock(&kvm_debugfs_lock);
     if (IS_ERR(dent))
         return 0;
 
     kvm->debugfs_dentry = dent;
     kvm->debugfs_stat_data = kcalloc(kvm_debugfs_num_entries,
                      sizeof(*kvm->debugfs_stat_data),
                      GFP_KERNEL_ACCOUNT);
     if (!kvm->debugfs_stat_data)
         goto out_err;
 
     for (i = 0; i < kvm_vm_stats_header.num_desc; ++i) {
         pdesc = &kvm_vm_stats_desc[i];
         stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT);
         if (!stat_data)
             goto out_err;
 
         stat_data->kvm = kvm;
         stat_data->desc = pdesc;
         stat_data->kind = KVM_STAT_VM;
         kvm->debugfs_stat_data[i] = stat_data;
         debugfs_create_file(pdesc->name, kvm_stats_debugfs_mode(pdesc),
                     kvm->debugfs_dentry, stat_data,
                     &stat_fops_per_vm);
     }
 
     for (i = 0; i < kvm_vcpu_stats_header.num_desc; ++i) {
         pdesc = &kvm_vcpu_stats_desc[i];
         stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT);
         if (!stat_data)
             goto out_err;
 
         stat_data->kvm = kvm;
         stat_data->desc = pdesc;
         stat_data->kind = KVM_STAT_VCPU;
         kvm->debugfs_stat_data[i + kvm_vm_stats_header.num_desc] = stat_data;
         debugfs_create_file(pdesc->name, kvm_stats_debugfs_mode(pdesc),
                     kvm->debugfs_dentry, stat_data,
                     &stat_fops_per_vm);
     }
 
     ret = kvm_arch_create_vm_debugfs(kvm);
     if (ret)
         goto out_err;
 
     return 0;
 out_err:
     kvm_destroy_vm_debugfs(kvm);
     return ret;
 }
 
 /*
  * Called after the VM is otherwise initialized, but just before adding it to
  * the vm_list.
  */
 int __weak kvm_arch_post_init_vm(struct kvm *kvm)
 {
     return 0;
 }
 
 /*
  * Called just after removing the VM from the vm_list, but before doing any
  * other destruction.
  */
 void __weak kvm_arch_pre_destroy_vm(struct kvm *kvm)
 {
 }
 
 /*
  * Called after per-vm debugfs created.  When called kvm->debugfs_dentry should
  * be setup already, so we can create arch-specific debugfs entries under it.
  * Cleanup should be automatic done in kvm_destroy_vm_debugfs() recursively, so
  * a per-arch destroy interface is not needed.
  */
 int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm)
 {
     return 0;
 }
 
 static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
 {
     struct kvm *kvm = kvm_arch_alloc_vm();
     struct kvm_memslots *slots;
     int r = -ENOMEM;
     int i, j;
 
     if (!kvm)
         return ERR_PTR(-ENOMEM);
 
     /* KVM is pinned via open("/dev/kvm"), the fd passed to this ioctl(). */
     __module_get(kvm_chardev_ops.owner);
 
     KVM_MMU_LOCK_INIT(kvm);
     mmgrab(current->mm);
     kvm->mm = current->mm;
     kvm_eventfd_init(kvm);
     mutex_init(&kvm->lock);
     mutex_init(&kvm->irq_lock);
     mutex_init(&kvm->slots_lock);
     mutex_init(&kvm->slots_arch_lock);
     spin_lock_init(&kvm->mn_invalidate_lock);
     rcuwait_init(&kvm->mn_memslots_update_rcuwait);
     xa_init(&kvm->vcpu_array);
 
     INIT_LIST_HEAD(&kvm->gpc_list);
     spin_lock_init(&kvm->gpc_lock);
 
     INIT_LIST_HEAD(&kvm->devices);
     kvm->max_vcpus = KVM_MAX_VCPUS;
 
     BUILD_BUG_ON(KVM_MEM_SLOTS_NUM > SHRT_MAX);
 
     /*
      * Force subsequent debugfs file creations to fail if the VM directory
      * is not created (by kvm_create_vm_debugfs()).
      */
     kvm->debugfs_dentry = ERR_PTR(-ENOENT);
 
     snprintf(kvm->stats_id, sizeof(kvm->stats_id), "kvm-%d",
          task_pid_nr(current));
 
     if (init_srcu_struct(&kvm->srcu))
         goto out_err_no_srcu;
     if (init_srcu_struct(&kvm->irq_srcu))
         goto out_err_no_irq_srcu;
 
     refcount_set(&kvm->users_count, 1);
     for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
         for (j = 0; j < 2; j++) {
             slots = &kvm->__memslots[i][j];
 
             atomic_long_set(&slots->last_used_slot, (unsigned long)NULL);
             slots->hva_tree = RB_ROOT_CACHED;
             slots->gfn_tree = RB_ROOT;
             hash_init(slots->id_hash);
             slots->node_idx = j;
 
             /* Generations must be different for each address space. */
             slots->generation = i;
         }
 
         rcu_assign_pointer(kvm->memslots[i], &kvm->__memslots[i][0]);
     }
 
     for (i = 0; i < KVM_NR_BUSES; i++) {
         rcu_assign_pointer(kvm->buses[i],
             kzalloc(sizeof(struct kvm_io_bus), GFP_KERNEL_ACCOUNT));
         if (!kvm->buses[i])
             goto out_err_no_arch_destroy_vm;
     }
 
     kvm->max_halt_poll_ns = halt_poll_ns;
 
     r = kvm_arch_init_vm(kvm, type);
     if (r)
         goto out_err_no_arch_destroy_vm;
 
     r = hardware_enable_all();
     if (r)
         goto out_err_no_disable;
 
 #ifdef CONFIG_HAVE_KVM_IRQFD
     INIT_HLIST_HEAD(&kvm->irq_ack_notifier_list);
 #endif
 
     r = kvm_init_mmu_notifier(kvm);
     if (r)
         goto out_err_no_mmu_notifier;
 
     r = kvm_coalesced_mmio_init(kvm);
     if (r < 0)
         goto out_no_coalesced_mmio;
 
     r = kvm_create_vm_debugfs(kvm, fdname);
     if (r)
         goto out_err_no_debugfs;
 
     r = kvm_arch_post_init_vm(kvm);
     if (r)
         goto out_err;
 
     mutex_lock(&kvm_lock);
     list_add(&kvm->vm_list, &vm_list);
     mutex_unlock(&kvm_lock);
 
     preempt_notifier_inc();
     kvm_init_pm_notifier(kvm);
 
     return kvm;
 
 out_err:
     kvm_destroy_vm_debugfs(kvm);
 out_err_no_debugfs:
     kvm_coalesced_mmio_free(kvm);
 out_no_coalesced_mmio:
 #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
     if (kvm->mmu_notifier.ops)
         mmu_notifier_unregister(&kvm->mmu_notifier, current->mm);
 #endif
 out_err_no_mmu_notifier:
     hardware_disable_all();
 out_err_no_disable:
     kvm_arch_destroy_vm(kvm);
 out_err_no_arch_destroy_vm:
     WARN_ON_ONCE(!refcount_dec_and_test(&kvm->users_count));
     for (i = 0; i < KVM_NR_BUSES; i++)
         kfree(kvm_get_bus(kvm, i));
     cleanup_srcu_struct(&kvm->irq_srcu);
 out_err_no_irq_srcu:
     cleanup_srcu_struct(&kvm->srcu);
 out_err_no_srcu:
     kvm_arch_free_vm(kvm);
     mmdrop(current->mm);
     module_put(kvm_chardev_ops.owner);
     return ERR_PTR(r);
 }
 
 static void kvm_destroy_devices(struct kvm *kvm)
 {
     struct kvm_device *dev, *tmp;
 
     /*
      * We do not need to take the kvm->lock here, because nobody else
      * has a reference to the struct kvm at this point and therefore
      * cannot access the devices list anyhow.
      */
     list_for_each_entry_safe(dev, tmp, &kvm->devices, vm_node) {
         list_del(&dev->vm_node);
         dev->ops->destroy(dev);
     }
 }
 
 static void kvm_destroy_vm(struct kvm *kvm)
 {
     int i;
     struct mm_struct *mm = kvm->mm;
 
     kvm_destroy_pm_notifier(kvm);
     kvm_uevent_notify_change(KVM_EVENT_DESTROY_VM, kvm);
     kvm_destroy_vm_debugfs(kvm);
     kvm_arch_sync_events(kvm);
     mutex_lock(&kvm_lock);
     list_del(&kvm->vm_list);
     mutex_unlock(&kvm_lock);
     kvm_arch_pre_destroy_vm(kvm);
 
     kvm_free_irq_routing(kvm);
     for (i = 0; i < KVM_NR_BUSES; i++) {
         struct kvm_io_bus *bus = kvm_get_bus(kvm, i);
 
         if (bus)
             kvm_io_bus_destroy(bus);
         kvm->buses[i] = NULL;
     }
     kvm_coalesced_mmio_free(kvm);
 #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
     mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm);
     /*
      * At this point, pending calls to invalidate_range_start()
      * have completed but no more MMU notifiers will run, so
      * mn_active_invalidate_count may remain unbalanced.
      * No threads can be waiting in install_new_memslots as the
      * last reference on KVM has been dropped, but freeing
      * memslots would deadlock without this manual intervention.
      */
     WARN_ON(rcuwait_active(&kvm->mn_memslots_update_rcuwait));
     kvm->mn_active_invalidate_count = 0;
 #else
     kvm_flush_shadow_all(kvm);
 #endif
     kvm_arch_destroy_vm(kvm);
     kvm_destroy_devices(kvm);
     for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
         kvm_free_memslots(kvm, &kvm->__memslots[i][0]);
         kvm_free_memslots(kvm, &kvm->__memslots[i][1]);
     }
     cleanup_srcu_struct(&kvm->irq_srcu);
     cleanup_srcu_struct(&kvm->srcu);
     kvm_arch_free_vm(kvm);
     preempt_notifier_dec();
     hardware_disable_all();
     mmdrop(mm);
     module_put(kvm_chardev_ops.owner);
 }
 
 void kvm_get_kvm(struct kvm *kvm)
 {
     refcount_inc(&kvm->users_count);
 }
 EXPORT_SYMBOL_GPL(kvm_get_kvm);
 
 /*
  * Make sure the vm is not during destruction, which is a safe version of
  * kvm_get_kvm().  Return true if kvm referenced successfully, false otherwise.
  */
 bool kvm_get_kvm_safe(struct kvm *kvm)
 {
     return refcount_inc_not_zero(&kvm->users_count);
 }
 EXPORT_SYMBOL_GPL(kvm_get_kvm_safe);
 
 void kvm_put_kvm(struct kvm *kvm)
 {
     if (refcount_dec_and_test(&kvm->users_count))
         kvm_destroy_vm(kvm);
 }
 EXPORT_SYMBOL_GPL(kvm_put_kvm);
 
 /*
  * Used to put a reference that was taken on behalf of an object associated
  * with a user-visible file descriptor, e.g. a vcpu or device, if installation
  * of the new file descriptor fails and the reference cannot be transferred to
  * its final owner.  In such cases, the caller is still actively using @kvm and
  * will fail miserably if the refcount unexpectedly hits zero.
  */
 void kvm_put_kvm_no_destroy(struct kvm *kvm)
 {
     WARN_ON(refcount_dec_and_test(&kvm->users_count));
 }
 EXPORT_SYMBOL_GPL(kvm_put_kvm_no_destroy);
 
 static int kvm_vm_release(struct inode *inode, struct file *filp)
 {
     struct kvm *kvm = filp->private_data;
 
     kvm_irqfd_release(kvm);
 
     kvm_put_kvm(kvm);
     return 0;
 }
 
 /*
  * Allocation size is twice as large as the actual dirty bitmap size.
  * See kvm_vm_ioctl_get_dirty_log() why this is needed.
  */
 static int kvm_alloc_dirty_bitmap(struct kvm_memory_slot *memslot)
 {
     unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(memslot);
 
     memslot->dirty_bitmap = __vcalloc(2, dirty_bytes, GFP_KERNEL_ACCOUNT);
     if (!memslot->dirty_bitmap)
         return -ENOMEM;
 
     return 0;
 }
 
 static struct kvm_memslots *kvm_get_inactive_memslots(struct kvm *kvm, int as_id)
 {
     struct kvm_memslots *active = __kvm_memslots(kvm, as_id);
     int node_idx_inactive = active->node_idx ^ 1;
 
     return &kvm->__memslots[as_id][node_idx_inactive];
 }
 
 /*
  * Helper to get the address space ID when one of memslot pointers may be NULL.
  * This also serves as a sanity that at least one of the pointers is non-NULL,
  * and that their address space IDs don't diverge.
  */
 static int kvm_memslots_get_as_id(struct kvm_memory_slot *a,
                   struct kvm_memory_slot *b)
 {
     if (WARN_ON_ONCE(!a && !b))
         return 0;
 
     if (!a)
         return b->as_id;
     if (!b)
         return a->as_id;
 
     WARN_ON_ONCE(a->as_id != b->as_id);
     return a->as_id;
 }
 
 static void kvm_insert_gfn_node(struct kvm_memslots *slots,
                 struct kvm_memory_slot *slot)
 {
     struct rb_root *gfn_tree = &slots->gfn_tree;
     struct rb_node **node, *parent;
     int idx = slots->node_idx;
 
     parent = NULL;
     for (node = &gfn_tree->rb_node; *node; ) {
         struct kvm_memory_slot *tmp;
 
         tmp = container_of(*node, struct kvm_memory_slot, gfn_node[idx]);
         parent = *node;
         if (slot->base_gfn < tmp->base_gfn)
             node = &(*node)->rb_left;
         else if (slot->base_gfn > tmp->base_gfn)
             node = &(*node)->rb_right;
         else
             BUG();
     }
 
     rb_link_node(&slot->gfn_node[idx], parent, node);
     rb_insert_color(&slot->gfn_node[idx], gfn_tree);
 }
 
 static void kvm_erase_gfn_node(struct kvm_memslots *slots,
                    struct kvm_memory_slot *slot)
 {
     rb_erase(&slot->gfn_node[slots->node_idx], &slots->gfn_tree);
 }
 
 static void kvm_replace_gfn_node(struct kvm_memslots *slots,
                  struct kvm_memory_slot *old,
                  struct kvm_memory_slot *new)
 {
     int idx = slots->node_idx;
 
     WARN_ON_ONCE(old->base_gfn != new->base_gfn);
 
     rb_replace_node(&old->gfn_node[idx], &new->gfn_node[idx],
             &slots->gfn_tree);
 }
 
 /*
  * Replace @old with @new in the inactive memslots.
  *
  * With NULL @old this simply adds @new.
  * With NULL @new this simply removes @old.
  *
  * If @new is non-NULL its hva_node[slots_idx] range has to be set
  * appropriately.
  */
 static void kvm_replace_memslot(struct kvm *kvm,
                 struct kvm_memory_slot *old,
                 struct kvm_memory_slot *new)
 {
     int as_id = kvm_memslots_get_as_id(old, new);
     struct kvm_memslots *slots = kvm_get_inactive_memslots(kvm, as_id);
     int idx = slots->node_idx;
 
     if (old) {
         hash_del(&old->id_node[idx]);
         interval_tree_remove(&old->hva_node[idx], &slots->hva_tree);
 
         if ((long)old == atomic_long_read(&slots->last_used_slot))
             atomic_long_set(&slots->last_used_slot, (long)new);
 
         if (!new) {
             kvm_erase_gfn_node(slots, old);
             return;
         }
     }
 
     /*
      * Initialize @new's hva range.  Do this even when replacing an @old
      * slot, kvm_copy_memslot() deliberately does not touch node data.
      */
     new->hva_node[idx].start = new->userspace_addr;
     new->hva_node[idx].last = new->userspace_addr +
                   (new->npages << PAGE_SHIFT) - 1;
 
     /*
      * (Re)Add the new memslot.  There is no O(1) interval_tree_replace(),
      * hva_node needs to be swapped with remove+insert even though hva can't
      * change when replacing an existing slot.
      */
     hash_add(slots->id_hash, &new->id_node[idx], new->id);
     interval_tree_insert(&new->hva_node[idx], &slots->hva_tree);
 
     /*
      * If the memslot gfn is unchanged, rb_replace_node() can be used to
      * switch the node in the gfn tree instead of removing the old and
      * inserting the new as two separate operations. Replacement is a
      * single O(1) operation versus two O(log(n)) operations for
      * remove+insert.
      */
     if (old && old->base_gfn == new->base_gfn) {
         kvm_replace_gfn_node(slots, old, new);
     } else {
         if (old)
             kvm_erase_gfn_node(slots, old);
         kvm_insert_gfn_node(slots, new);
     }
 }
 
 static int check_memory_region_flags(const struct kvm_userspace_memory_region *mem)
 {
     u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
 
 #ifdef __KVM_HAVE_READONLY_MEM
     valid_flags |= KVM_MEM_READONLY;
 #endif
 
     if (mem->flags & ~valid_flags)
         return -EINVAL;
 
     return 0;
 }
 
 static void kvm_swap_active_memslots(struct kvm *kvm, int as_id)
 {
     struct kvm_memslots *slots = kvm_get_inactive_memslots(kvm, as_id);
 
     /* Grab the generation from the activate memslots. */
     u64 gen = __kvm_memslots(kvm, as_id)->generation;
 
     WARN_ON(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS);
     slots->generation = gen | KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS;
 
     /*
      * Do not store the new memslots while there are invalidations in
      * progress, otherwise the locking in invalidate_range_start and
      * invalidate_range_end will be unbalanced.
      */
     spin_lock(&kvm->mn_invalidate_lock);
     prepare_to_rcuwait(&kvm->mn_memslots_update_rcuwait);
     while (kvm->mn_active_invalidate_count) {
         set_current_state(TASK_UNINTERRUPTIBLE);
         spin_unlock(&kvm->mn_invalidate_lock);
         schedule();
         spin_lock(&kvm->mn_invalidate_lock);
     }
     finish_rcuwait(&kvm->mn_memslots_update_rcuwait);
     rcu_assign_pointer(kvm->memslots[as_id], slots);
     spin_unlock(&kvm->mn_invalidate_lock);
 
     /*
      * Acquired in kvm_set_memslot. Must be released before synchronize
      * SRCU below in order to avoid deadlock with another thread
      * acquiring the slots_arch_lock in an srcu critical section.
      */
     mutex_unlock(&kvm->slots_arch_lock);
 
     synchronize_srcu_expedited(&kvm->srcu);
 
     /*
      * Increment the new memslot generation a second time, dropping the
      * update in-progress flag and incrementing the generation based on
      * the number of address spaces.  This provides a unique and easily
      * identifiable generation number while the memslots are in flux.
      */
     gen = slots->generation & ~KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS;
 
     /*
      * Generations must be unique even across address spaces.  We do not need
      * a global counter for that, instead the generation space is evenly split
      * across address spaces.  For example, with two address spaces, address
      * space 0 will use generations 0, 2, 4, ... while address space 1 will
      * use generations 1, 3, 5, ...
      */
     gen += KVM_ADDRESS_SPACE_NUM;
 
     kvm_arch_memslots_updated(kvm, gen);
 
     slots->generation = gen;
 }
 
 static int kvm_prepare_memory_region(struct kvm *kvm,
                      const struct kvm_memory_slot *old,
                      struct kvm_memory_slot *new,
                      enum kvm_mr_change change)
 {
     int r;
 
     /*
      * If dirty logging is disabled, nullify the bitmap; the old bitmap
      * will be freed on "commit".  If logging is enabled in both old and
      * new, reuse the existing bitmap.  If logging is enabled only in the
      * new and KVM isn't using a ring buffer, allocate and initialize a
      * new bitmap.
      */
     if (change != KVM_MR_DELETE) {
         if (!(new->flags & KVM_MEM_LOG_DIRTY_PAGES))
             new->dirty_bitmap = NULL;
         else if (old && old->dirty_bitmap)
             new->dirty_bitmap = old->dirty_bitmap;
         else if (!kvm->dirty_ring_size) {
             r = kvm_alloc_dirty_bitmap(new);
             if (r)
                 return r;
 
             if (kvm_dirty_log_manual_protect_and_init_set(kvm))
                 bitmap_set(new->dirty_bitmap, 0, new->npages);
         }
     }
 
     r = kvm_arch_prepare_memory_region(kvm, old, new, change);
 
     /* Free the bitmap on failure if it was allocated above. */
     if (r && new && new->dirty_bitmap && (!old || !old->dirty_bitmap))
         kvm_destroy_dirty_bitmap(new);
 
     return r;
 }
 
 static void kvm_commit_memory_region(struct kvm *kvm,
                      struct kvm_memory_slot *old,
                      const struct kvm_memory_slot *new,
                      enum kvm_mr_change change)
 {
     /*
      * Update the total number of memslot pages before calling the arch
      * hook so that architectures can consume the result directly.
      */
     if (change == KVM_MR_DELETE)
         kvm->nr_memslot_pages -= old->npages;
     else if (change == KVM_MR_CREATE)
         kvm->nr_memslot_pages += new->npages;
 
     kvm_arch_commit_memory_region(kvm, old, new, change);
 
     switch (change) {
     case KVM_MR_CREATE:
         /* Nothing more to do. */
         break;
     case KVM_MR_DELETE:
         /* Free the old memslot and all its metadata. */
         kvm_free_memslot(kvm, old);
         break;
     case KVM_MR_MOVE:
     case KVM_MR_FLAGS_ONLY:
         /*
          * Free the dirty bitmap as needed; the below check encompasses
          * both the flags and whether a ring buffer is being used)
          */
         if (old->dirty_bitmap && !new->dirty_bitmap)
             kvm_destroy_dirty_bitmap(old);
 
         /*
          * The final quirk.  Free the detached, old slot, but only its
          * memory, not any metadata.  Metadata, including arch specific
          * data, may be reused by @new.
          */
         kfree(old);
         break;
     default:
         BUG();
     }
 }
 
 /*
  * Activate @new, which must be installed in the inactive slots by the caller,
  * by swapping the active slots and then propagating @new to @old once @old is
  * unreachable and can be safely modified.
  *
  * With NULL @old this simply adds @new to @active (while swapping the sets).
  * With NULL @new this simply removes @old from @active and frees it
  * (while also swapping the sets).
  */
 static void kvm_activate_memslot(struct kvm *kvm,
                  struct kvm_memory_slot *old,
                  struct kvm_memory_slot *new)
 {
     int as_id = kvm_memslots_get_as_id(old, new);
 
     kvm_swap_active_memslots(kvm, as_id);
 
     /* Propagate the new memslot to the now inactive memslots. */
     kvm_replace_memslot(kvm, old, new);
 }
 
 static void kvm_copy_memslot(struct kvm_memory_slot *dest,
                  const struct kvm_memory_slot *src)
 {
     dest->base_gfn = src->base_gfn;
     dest->npages = src->npages;
     dest->dirty_bitmap = src->dirty_bitmap;
     dest->arch = src->arch;
     dest->userspace_addr = src->userspace_addr;
     dest->flags = src->flags;
     dest->id = src->id;
     dest->as_id = src->as_id;
 }
 
 static void kvm_invalidate_memslot(struct kvm *kvm,
                    struct kvm_memory_slot *old,
                    struct kvm_memory_slot *invalid_slot)
 {
     /*
      * Mark the current slot INVALID.  As with all memslot modifications,
      * this must be done on an unreachable slot to avoid modifying the
      * current slot in the active tree.
      */
     kvm_copy_memslot(invalid_slot, old);
     invalid_slot->flags |= KVM_MEMSLOT_INVALID;
     kvm_replace_memslot(kvm, old, invalid_slot);
 
     /*
      * Activate the slot that is now marked INVALID, but don't propagate
      * the slot to the now inactive slots. The slot is either going to be
      * deleted or recreated as a new slot.
      */
     kvm_swap_active_memslots(kvm, old->as_id);
 
     /*
      * From this point no new shadow pages pointing to a deleted, or moved,
      * memslot will be created.  Validation of sp->gfn happens in:
      *  - gfn_to_hva (kvm_read_guest, gfn_to_pfn)
      *  - kvm_is_visible_gfn (mmu_check_root)
      */
     kvm_arch_flush_shadow_memslot(kvm, old);
     kvm_arch_guest_memory_reclaimed(kvm);
 
     /* Was released by kvm_swap_active_memslots, reacquire. */
     mutex_lock(&kvm->slots_arch_lock);
 
     /*
      * Copy the arch-specific field of the newly-installed slot back to the
      * old slot as the arch data could have changed between releasing
      * slots_arch_lock in install_new_memslots() and re-acquiring the lock
      * above.  Writers are required to retrieve memslots *after* acquiring
      * slots_arch_lock, thus the active slot's data is guaranteed to be fresh.
      */
     old->arch = invalid_slot->arch;
 }
 
 static void kvm_create_memslot(struct kvm *kvm,
                    struct kvm_memory_slot *new)
 {
     /* Add the new memslot to the inactive set and activate. */
     kvm_replace_memslot(kvm, NULL, new);
     kvm_activate_memslot(kvm, NULL, new);
 }
 
 static void kvm_delete_memslot(struct kvm *kvm,
                    struct kvm_memory_slot *old,
                    struct kvm_memory_slot *invalid_slot)
 {
     /*
      * Remove the old memslot (in the inactive memslots) by passing NULL as
      * the "new" slot, and for the invalid version in the active slots.
      */
     kvm_replace_memslot(kvm, old, NULL);
     kvm_activate_memslot(kvm, invalid_slot, NULL);
 }
 
 static void kvm_move_memslot(struct kvm *kvm,
                  struct kvm_memory_slot *old,
                  struct kvm_memory_slot *new,
                  struct kvm_memory_slot *invalid_slot)
 {
     /*
      * Replace the old memslot in the inactive slots, and then swap slots
      * and replace the current INVALID with the new as well.
      */
     kvm_replace_memslot(kvm, old, new);
     kvm_activate_memslot(kvm, invalid_slot, new);
 }
 
 static void kvm_update_flags_memslot(struct kvm *kvm,
                      struct kvm_memory_slot *old,
                      struct kvm_memory_slot *new)
 {
     /*
      * Similar to the MOVE case, but the slot doesn't need to be zapped as
      * an intermediate step. Instead, the old memslot is simply replaced
      * with a new, updated copy in both memslot sets.
      */
     kvm_replace_memslot(kvm, old, new);
     kvm_activate_memslot(kvm, old, new);
 }
 
 static int kvm_set_memslot(struct kvm *kvm,
                struct kvm_memory_slot *old,
                struct kvm_memory_slot *new,
                enum kvm_mr_change change)
 {
     struct kvm_memory_slot *invalid_slot;
     int r;
 
     /*
      * Released in kvm_swap_active_memslots.
      *
      * Must be held from before the current memslots are copied until
      * after the new memslots are installed with rcu_assign_pointer,
      * then released before the synchronize srcu in kvm_swap_active_memslots.
      *
      * When modifying memslots outside of the slots_lock, must be held
      * before reading the pointer to the current memslots until after all
      * changes to those memslots are complete.
      *
      * These rules ensure that installing new memslots does not lose
      * changes made to the previous memslots.
      */
     mutex_lock(&kvm->slots_arch_lock);
 
     /*
      * Invalidate the old slot if it's being deleted or moved.  This is
      * done prior to actually deleting/moving the memslot to allow vCPUs to
      * continue running by ensuring there are no mappings or shadow pages
      * for the memslot when it is deleted/moved.  Without pre-invalidation
      * (and without a lock), a window would exist between effecting the
      * delete/move and committing the changes in arch code where KVM or a
      * guest could access a non-existent memslot.
      *
      * Modifications are done on a temporary, unreachable slot.  The old
      * slot needs to be preserved in case a later step fails and the
      * invalidation needs to be reverted.
      */
     if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
         invalid_slot = kzalloc(sizeof(*invalid_slot), GFP_KERNEL_ACCOUNT);
         if (!invalid_slot) {
             mutex_unlock(&kvm->slots_arch_lock);
             return -ENOMEM;
         }
         kvm_invalidate_memslot(kvm, old, invalid_slot);
     }
 
     r = kvm_prepare_memory_region(kvm, old, new, change);
     if (r) {
         /*
          * For DELETE/MOVE, revert the above INVALID change.  No
          * modifications required since the original slot was preserved
          * in the inactive slots.  Changing the active memslots also
          * release slots_arch_lock.
          */
         if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
             kvm_activate_memslot(kvm, invalid_slot, old);
             kfree(invalid_slot);
         } else {
             mutex_unlock(&kvm->slots_arch_lock);
         }
         return r;
     }
 
     /*
      * For DELETE and MOVE, the working slot is now active as the INVALID
      * version of the old slot.  MOVE is particularly special as it reuses
      * the old slot and returns a copy of the old slot (in working_slot).
      * For CREATE, there is no old slot.  For DELETE and FLAGS_ONLY, the
      * old slot is detached but otherwise preserved.
      */
     if (change == KVM_MR_CREATE)
         kvm_create_memslot(kvm, new);
     else if (change == KVM_MR_DELETE)
         kvm_delete_memslot(kvm, old, invalid_slot);
     else if (change == KVM_MR_MOVE)
         kvm_move_memslot(kvm, old, new, invalid_slot);
     else if (change == KVM_MR_FLAGS_ONLY)
         kvm_update_flags_memslot(kvm, old, new);
     else
         BUG();
 
     /* Free the temporary INVALID slot used for DELETE and MOVE. */
     if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
         kfree(invalid_slot);
 
     /*
      * No need to refresh new->arch, changes after dropping slots_arch_lock
      * will directly hit the final, active memslot.  Architectures are
      * responsible for knowing that new->arch may be stale.
      */
     kvm_commit_memory_region(kvm, old, new, change);
 
     return 0;
 }
 
 static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id,
                       gfn_t start, gfn_t end)
 {
     struct kvm_memslot_iter iter;
 
     kvm_for_each_memslot_in_gfn_range(&iter, slots, start, end) {
         if (iter.slot->id != id)
             return true;
     }
 
     return false;
 }
 
 /*
  * Allocate some memory and give it an address in the guest physical address
  * space.
  *
  * Discontiguous memory is allowed, mostly for framebuffers.
  *
  * Must be called holding kvm->slots_lock for write.
  */
 int __kvm_set_memory_region(struct kvm *kvm,
                 const struct kvm_userspace_memory_region *mem)
 {
     struct kvm_memory_slot *old, *new;
     struct kvm_memslots *slots;
     enum kvm_mr_change change;
     unsigned long npages;
     gfn_t base_gfn;
     int as_id, id;
     int r;
 
     r = check_memory_region_flags(mem);
     if (r)
         return r;
 
     as_id = mem->slot >> 16;
     id = (u16)mem->slot;
 
     /* General sanity checks */
     if ((mem->memory_size & (PAGE_SIZE - 1)) ||
         (mem->memory_size != (unsigned long)mem->memory_size))
         return -EINVAL;
     if (mem->guest_phys_addr & (PAGE_SIZE - 1))
         return -EINVAL;
     /* We can read the guest memory with __xxx_user() later on. */
     if ((mem->userspace_addr & (PAGE_SIZE - 1)) ||
         (mem->userspace_addr != untagged_addr(mem->userspace_addr)) ||
          !access_ok((void __user *)(unsigned long)mem->userspace_addr,
             mem->memory_size))
         return -EINVAL;
     if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM)
         return -EINVAL;
     if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
         return -EINVAL;
     if ((mem->memory_size >> PAGE_SHIFT) > KVM_MEM_MAX_NR_PAGES)
         return -EINVAL;
 
     slots = __kvm_memslots(kvm, as_id);
 
     /*
      * Note, the old memslot (and the pointer itself!) may be invalidated
      * and/or destroyed by kvm_set_memslot().
      */
     old = id_to_memslot(slots, id);
 
     if (!mem->memory_size) {
         if (!old || !old->npages)
             return -EINVAL;
 
         if (WARN_ON_ONCE(kvm->nr_memslot_pages < old->npages))
             return -EIO;
 
         return kvm_set_memslot(kvm, old, NULL, KVM_MR_DELETE);
     }
 
     base_gfn = (mem->guest_phys_addr >> PAGE_SHIFT);
     npages = (mem->memory_size >> PAGE_SHIFT);
 
     if (!old || !old->npages) {
         change = KVM_MR_CREATE;
 
         /*
          * To simplify KVM internals, the total number of pages across
          * all memslots must fit in an unsigned long.
          */
         if ((kvm->nr_memslot_pages + npages) < kvm->nr_memslot_pages)
             return -EINVAL;
     } else { /* Modify an existing slot. */
         if ((mem->userspace_addr != old->userspace_addr) ||
             (npages != old->npages) ||
             ((mem->flags ^ old->flags) & KVM_MEM_READONLY))
             return -EINVAL;
 
         if (base_gfn != old->base_gfn)
             change = KVM_MR_MOVE;
         else if (mem->flags != old->flags)
             change = KVM_MR_FLAGS_ONLY;
         else /* Nothing to change. */
             return 0;
     }
 
     if ((change == KVM_MR_CREATE || change == KVM_MR_MOVE) &&
         kvm_check_memslot_overlap(slots, id, base_gfn, base_gfn + npages))
         return -EEXIST;
 
     /* Allocate a slot that will persist in the memslot. */
     new = kzalloc(sizeof(*new), GFP_KERNEL_ACCOUNT);
     if (!new)
         return -ENOMEM;
 
     new->as_id = as_id;
     new->id = id;
     new->base_gfn = base_gfn;
     new->npages = npages;
     new->flags = mem->flags;
     new->userspace_addr = mem->userspace_addr;
 
     r = kvm_set_memslot(kvm, old, new, change);
     if (r)
         kfree(new);
     return r;
 }
 EXPORT_SYMBOL_GPL(__kvm_set_memory_region);
 
 int kvm_set_memory_region(struct kvm *kvm,
               const struct kvm_userspace_memory_region *mem)
 {
     int r;
 
     mutex_lock(&kvm->slots_lock);
     r = __kvm_set_memory_region(kvm, mem);
     mutex_unlock(&kvm->slots_lock);
     return r;
 }
 EXPORT_SYMBOL_GPL(kvm_set_memory_region);
 
 static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
                       struct kvm_userspace_memory_region *mem)
 {
     if ((u16)mem->slot >= KVM_USER_MEM_SLOTS)
         return -EINVAL;
 
     return kvm_set_memory_region(kvm, mem);
 }
 
 #ifndef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
 /**
  * kvm_get_dirty_log - get a snapshot of dirty pages
  * @kvm:    pointer to kvm instance
  * @log:    slot id and address to which we copy the log
  * @is_dirty:   set to '1' if any dirty pages were found
  * @memslot:    set to the associated memslot, always valid on success
  */
 int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
               int *is_dirty, struct kvm_memory_slot **memslot)
 {
     struct kvm_memslots *slots;
     int i, as_id, id;
     unsigned long n;
     unsigned long any = 0;
 
     /* Dirty ring tracking is exclusive to dirty log tracking */
     if (kvm->dirty_ring_size)
         return -ENXIO;
 
     *memslot = NULL;
     *is_dirty = 0;
 
     as_id = log->slot >> 16;
     id = (u16)log->slot;
     if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
         return -EINVAL;
 
     slots = __kvm_memslots(kvm, as_id);
     *memslot = id_to_memslot(slots, id);
     if (!(*memslot) || !(*memslot)->dirty_bitmap)
         return -ENOENT;
 
     kvm_arch_sync_dirty_log(kvm, *memslot);
 
     n = kvm_dirty_bitmap_bytes(*memslot);
 
     for (i = 0; !any && i < n/sizeof(long); ++i)
         any = (*memslot)->dirty_bitmap[i];
 
     if (copy_to_user(log->dirty_bitmap, (*memslot)->dirty_bitmap, n))
         return -EFAULT;
 
     if (any)
         *is_dirty = 1;
     return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_get_dirty_log);
 
 #else /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
 /**
  * kvm_get_dirty_log_protect - get a snapshot of dirty pages
  *  and reenable dirty page tracking for the corresponding pages.
  * @kvm:    pointer to kvm instance
  * @log:    slot id and address to which we copy the log
  *
  * We need to keep it in mind that VCPU threads can write to the bitmap
  * concurrently. So, to avoid losing track of dirty pages we keep the
  * following order:
  *
  *    1. Take a snapshot of the bit and clear it if needed.
  *    2. Write protect the corresponding page.
  *    3. Copy the snapshot to the userspace.
  *    4. Upon return caller flushes TLB's if needed.
  *
  * Between 2 and 4, the guest may write to the page using the remaining TLB
  * entry.  This is not a problem because the page is reported dirty using
  * the snapshot taken before and step 4 ensures that writes done after
  * exiting to userspace will be logged for the next call.
  *
  */
 static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log)
 {
     struct kvm_memslots *slots;
     struct kvm_memory_slot *memslot;
     int i, as_id, id;
     unsigned long n;
     unsigned long *dirty_bitmap;
     unsigned long *dirty_bitmap_buffer;
     bool flush;
 
     /* Dirty ring tracking is exclusive to dirty log tracking */
     if (kvm->dirty_ring_size)
         return -ENXIO;
 
     as_id = log->slot >> 16;
     id = (u16)log->slot;
     if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
         return -EINVAL;
 
     slots = __kvm_memslots(kvm, as_id);
     memslot = id_to_memslot(slots, id);
     if (!memslot || !memslot->dirty_bitmap)
         return -ENOENT;
 
     dirty_bitmap = memslot->dirty_bitmap;
 
     kvm_arch_sync_dirty_log(kvm, memslot);
 
     n = kvm_dirty_bitmap_bytes(memslot);
     flush = false;
     if (kvm->manual_dirty_log_protect) {
         /*
          * Unlike kvm_get_dirty_log, we always return false in *flush,
          * because no flush is needed until KVM_CLEAR_DIRTY_LOG.  There
          * is some code duplication between this function and
          * kvm_get_dirty_log, but hopefully all architecture
          * transition to kvm_get_dirty_log_protect and kvm_get_dirty_log
          * can be eliminated.
          */
         dirty_bitmap_buffer = dirty_bitmap;
     } else {
         dirty_bitmap_buffer = kvm_second_dirty_bitmap(memslot);
         memset(dirty_bitmap_buffer, 0, n);
 
         KVM_MMU_LOCK(kvm);
         for (i = 0; i < n / sizeof(long); i++) {
             unsigned long mask;
             gfn_t offset;
 
             if (!dirty_bitmap[i])
                 continue;
 
             flush = true;
             mask = xchg(&dirty_bitmap[i], 0);
             dirty_bitmap_buffer[i] = mask;
 
             offset = i * BITS_PER_LONG;
             kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot,
                                 offset, mask);
         }
         KVM_MMU_UNLOCK(kvm);
     }
 
     if (flush)
         kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
 
     if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n))
         return -EFAULT;
     return 0;
 }
 
 
 /**
  * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in a slot
  * @kvm: kvm instance
  * @log: slot id and address to which we copy the log
  *
  * Steps 1-4 below provide general overview of dirty page logging. See
  * kvm_get_dirty_log_protect() function description for additional details.
  *
  * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we
  * always flush the TLB (step 4) even if previous step failed  and the dirty
  * bitmap may be corrupt. Regardless of previous outcome the KVM logging API
  * does not preclude user space subsequent dirty log read. Flushing TLB ensures
  * writes will be marked dirty for next log read.
  *
  *   1. Take a snapshot of the bit and clear it if needed.
  *   2. Write protect the corresponding page.
  *   3. Copy the snapshot to the userspace.
  *   4. Flush TLB's if needed.
  */
 static int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
                       struct kvm_dirty_log *log)
 {
     int r;
 
     mutex_lock(&kvm->slots_lock);
 
     r = kvm_get_dirty_log_protect(kvm, log);
 
     mutex_unlock(&kvm->slots_lock);
     return r;
 }
 
 /**
  * kvm_clear_dirty_log_protect - clear dirty bits in the bitmap
  *  and reenable dirty page tracking for the corresponding pages.
  * @kvm:    pointer to kvm instance
  * @log:    slot id and address from which to fetch the bitmap of dirty pages
  */
 static int kvm_clear_dirty_log_protect(struct kvm *kvm,
                        struct kvm_clear_dirty_log *log)
 {
     struct kvm_memslots *slots;
     struct kvm_memory_slot *memslot;
     int as_id, id;
     gfn_t offset;
     unsigned long i, n;
     unsigned long *dirty_bitmap;
     unsigned long *dirty_bitmap_buffer;
     bool flush;
 
     /* Dirty ring tracking is exclusive to dirty log tracking */
     if (kvm->dirty_ring_size)
         return -ENXIO;
 
     as_id = log->slot >> 16;
     id = (u16)log->slot;
     if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
         return -EINVAL;
 
     if (log->first_page & 63)
         return -EINVAL;
 
     slots = __kvm_memslots(kvm, as_id);
     memslot = id_to_memslot(slots, id);
     if (!memslot || !memslot->dirty_bitmap)
         return -ENOENT;
 
     dirty_bitmap = memslot->dirty_bitmap;
 
     n = ALIGN(log->num_pages, BITS_PER_LONG) / 8;
 
     if (log->first_page > memslot->npages ||
         log->num_pages > memslot->npages - log->first_page ||
         (log->num_pages < memslot->npages - log->first_page && (log->num_pages & 63)))
         return -EINVAL;
 
     kvm_arch_sync_dirty_log(kvm, memslot);
 
     flush = false;
     dirty_bitmap_buffer = kvm_second_dirty_bitmap(memslot);
     if (copy_from_user(dirty_bitmap_buffer, log->dirty_bitmap, n))
         return -EFAULT;
 
     KVM_MMU_LOCK(kvm);
     for (offset = log->first_page, i = offset / BITS_PER_LONG,
          n = DIV_ROUND_UP(log->num_pages, BITS_PER_LONG); n--;
          i++, offset += BITS_PER_LONG) {
         unsigned long mask = *dirty_bitmap_buffer++;
         atomic_long_t *p = (atomic_long_t *) &dirty_bitmap[i];
         if (!mask)
             continue;
 
         mask &= atomic_long_fetch_andnot(mask, p);
 
         /*
          * mask contains the bits that really have been cleared.  This
          * never includes any bits beyond the length of the memslot (if
          * the length is not aligned to 64 pages), therefore it is not
          * a problem if userspace sets them in log->dirty_bitmap.
         */
         if (mask) {
             flush = true;
             kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot,
                                 offset, mask);
         }
     }
     KVM_MMU_UNLOCK(kvm);
 
     if (flush)
         kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
 
     return 0;
 }
 
 static int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm,
                     struct kvm_clear_dirty_log *log)
 {
     int r;
 
     mutex_lock(&kvm->slots_lock);
 
     r = kvm_clear_dirty_log_protect(kvm, log);
 
     mutex_unlock(&kvm->slots_lock);
     return r;
 }
 #endif /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
 
 struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
 {
     return __gfn_to_memslot(kvm_memslots(kvm), gfn);
 }
 EXPORT_SYMBOL_GPL(gfn_to_memslot);
 
 struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
     struct kvm_memslots *slots = kvm_vcpu_memslots(vcpu);
     u64 gen = slots->generation;
     struct kvm_memory_slot *slot;
 
     /*
      * This also protects against using a memslot from a different address space,
      * since different address spaces have different generation numbers.
      */
     if (unlikely(gen != vcpu->last_used_slot_gen)) {
         vcpu->last_used_slot = NULL;
         vcpu->last_used_slot_gen = gen;
     }
 
     slot = try_get_memslot(vcpu->last_used_slot, gfn);
     if (slot)
         return slot;
 
     /*
      * Fall back to searching all memslots. We purposely use
      * search_memslots() instead of __gfn_to_memslot() to avoid
      * thrashing the VM-wide last_used_slot in kvm_memslots.
      */
     slot = search_memslots(slots, gfn, false);
     if (slot) {
         vcpu->last_used_slot = slot;
         return slot;
     }
 
     return NULL;
 }
 
 bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
 {
     struct kvm_memory_slot *memslot = gfn_to_memslot(kvm, gfn);
 
     return kvm_is_visible_memslot(memslot);
 }
 EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);
 
 bool kvm_vcpu_is_visible_gfn(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
     struct kvm_memory_slot *memslot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
 
     return kvm_is_visible_memslot(memslot);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_is_visible_gfn);
 
 unsigned long kvm_host_page_size(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
     struct vm_area_struct *vma;
     unsigned long addr, size;
 
     size = PAGE_SIZE;
 
     addr = kvm_vcpu_gfn_to_hva_prot(vcpu, gfn, NULL);
     if (kvm_is_error_hva(addr))
         return PAGE_SIZE;
 
     mmap_read_lock(current->mm);
     vma = find_vma(current->mm, addr);
     if (!vma)
         goto out;
 
     size = vma_kernel_pagesize(vma);
 
 out:
     mmap_read_unlock(current->mm);
 
     return size;
 }
 
 static bool memslot_is_readonly(const struct kvm_memory_slot *slot)
 {
     return slot->flags & KVM_MEM_READONLY;
 }
 
 static unsigned long __gfn_to_hva_many(const struct kvm_memory_slot *slot, gfn_t gfn,
                        gfn_t *nr_pages, bool write)
 {
     if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
         return KVM_HVA_ERR_BAD;
 
     if (memslot_is_readonly(slot) && write)
         return KVM_HVA_ERR_RO_BAD;
 
     if (nr_pages)
         *nr_pages = slot->npages - (gfn - slot->base_gfn);
 
     return __gfn_to_hva_memslot(slot, gfn);
 }
 
 static unsigned long gfn_to_hva_many(struct kvm_memory_slot *slot, gfn_t gfn,
                      gfn_t *nr_pages)
 {
     return __gfn_to_hva_many(slot, gfn, nr_pages, true);
 }
 
 unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot,
                     gfn_t gfn)
 {
     return gfn_to_hva_many(slot, gfn, NULL);
 }
 EXPORT_SYMBOL_GPL(gfn_to_hva_memslot);
 
 unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
 {
     return gfn_to_hva_many(gfn_to_memslot(kvm, gfn), gfn, NULL);
 }
 EXPORT_SYMBOL_GPL(gfn_to_hva);
 
 unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
     return gfn_to_hva_many(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn, NULL);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_hva);
 
 /*
  * Return the hva of a @gfn and the R/W attribute if possible.
  *
  * @slot: the kvm_memory_slot which contains @gfn
  * @gfn: the gfn to be translated
  * @writable: used to return the read/write attribute of the @slot if the hva
  * is valid and @writable is not NULL
  */
 unsigned long gfn_to_hva_memslot_prot(struct kvm_memory_slot *slot,
                       gfn_t gfn, bool *writable)
 {
     unsigned long hva = __gfn_to_hva_many(slot, gfn, NULL, false);
 
     if (!kvm_is_error_hva(hva) && writable)
         *writable = !memslot_is_readonly(slot);
 
     return hva;
 }
 
 unsigned long gfn_to_hva_prot(struct kvm *kvm, gfn_t gfn, bool *writable)
 {
     struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
 
     return gfn_to_hva_memslot_prot(slot, gfn, writable);
 }
 
 unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable)
 {
     struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
 
     return gfn_to_hva_memslot_prot(slot, gfn, writable);
 }
 
 static inline int check_user_page_hwpoison(unsigned long addr)
 {
     int rc, flags = FOLL_HWPOISON | FOLL_WRITE;
 
     rc = get_user_pages(addr, 1, flags, NULL, NULL);
     return rc == -EHWPOISON;
 }
 
 /*
  * The fast path to get the writable pfn which will be stored in @pfn,
  * true indicates success, otherwise false is returned.  It's also the
  * only part that runs if we can in atomic context.
  */
 static bool hva_to_pfn_fast(unsigned long addr, bool write_fault,
                 bool *writable, kvm_pfn_t *pfn)
 {
     struct page *page[1];
 
     /*
      * Fast pin a writable pfn only if it is a write fault request
      * or the caller allows to map a writable pfn for a read fault
      * request.
      */
     if (!(write_fault || writable))
         return false;
 
     if (get_user_page_fast_only(addr, FOLL_WRITE, page)) {
         *pfn = page_to_pfn(page[0]);
 
         if (writable)
             *writable = true;
         return true;
     }
 
     return false;
 }
 
 /*
  * The slow path to get the pfn of the specified host virtual address,
  * 1 indicates success, -errno is returned if error is detected.
  */
 static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
                bool *writable, kvm_pfn_t *pfn)
 {
     unsigned int flags = FOLL_HWPOISON;
     struct page *page;
     int npages;
 
     might_sleep();
 
     if (writable)
         *writable = write_fault;
 
     if (write_fault)
         flags |= FOLL_WRITE;
     if (async)
         flags |= FOLL_NOWAIT;
 
     npages = get_user_pages_unlocked(addr, 1, &page, flags);
     if (npages != 1)
         return npages;
 
     /* map read fault as writable if possible */
     if (unlikely(!write_fault) && writable) {
         struct page *wpage;
 
         if (get_user_page_fast_only(addr, FOLL_WRITE, &wpage)) {
             *writable = true;
             put_page(page);
             page = wpage;
         }
     }
     *pfn = page_to_pfn(page);
     return npages;
 }
 
 static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault)
 {
     if (unlikely(!(vma->vm_flags & VM_READ)))
         return false;
 
     if (write_fault && (unlikely(!(vma->vm_flags & VM_WRITE))))
         return false;
 
     return true;
 }
 
 static int kvm_try_get_pfn(kvm_pfn_t pfn)
 {
     struct page *page = kvm_pfn_to_refcounted_page(pfn);
 
     if (!page)
         return 1;
 
     return get_page_unless_zero(page);
 }
 
 static int hva_to_pfn_remapped(struct vm_area_struct *vma,
                    unsigned long addr, bool write_fault,
                    bool *writable, kvm_pfn_t *p_pfn)
 {
     kvm_pfn_t pfn;
     pte_t *ptep;
     spinlock_t *ptl;
     int r;
 
     r = follow_pte(vma->vm_mm, addr, &ptep, &ptl);
     if (r) {
         /*
          * get_user_pages fails for VM_IO and VM_PFNMAP vmas and does
          * not call the fault handler, so do it here.
          */
         bool unlocked = false;
         r = fixup_user_fault(current->mm, addr,
                      (write_fault ? FAULT_FLAG_WRITE : 0),
                      &unlocked);
         if (unlocked)
             return -EAGAIN;
         if (r)
             return r;
 
         r = follow_pte(vma->vm_mm, addr, &ptep, &ptl);
         if (r)
             return r;
     }
 
     if (write_fault && !pte_write(*ptep)) {
         pfn = KVM_PFN_ERR_RO_FAULT;
         goto out;
     }
 
     if (writable)
         *writable = pte_write(*ptep);
     pfn = pte_pfn(*ptep);
 
     /*
      * Get a reference here because callers of *hva_to_pfn* and
      * *gfn_to_pfn* ultimately call kvm_release_pfn_clean on the
      * returned pfn.  This is only needed if the VMA has VM_MIXEDMAP
      * set, but the kvm_try_get_pfn/kvm_release_pfn_clean pair will
      * simply do nothing for reserved pfns.
      *
      * Whoever called remap_pfn_range is also going to call e.g.
      * unmap_mapping_range before the underlying pages are freed,
      * causing a call to our MMU notifier.
      *
      * Certain IO or PFNMAP mappings can be backed with valid
      * struct pages, but be allocated without refcounting e.g.,
      * tail pages of non-compound higher order allocations, which
      * would then underflow the refcount when the caller does the
      * required put_page. Don't allow those pages here.
      */ 
     if (!kvm_try_get_pfn(pfn))
         r = -EFAULT;
 
 out:
     pte_unmap_unlock(ptep, ptl);
     *p_pfn = pfn;
 
     return r;
 }
 
 /*
  * Pin guest page in memory and return its pfn.
  * @addr: host virtual address which maps memory to the guest
  * @atomic: whether this function can sleep
  * @async: whether this function need to wait IO complete if the
  *         host page is not in the memory
  * @write_fault: whether we should get a writable host page
  * @writable: whether it allows to map a writable host page for !@write_fault
  *
  * The function will map a writable host page for these two cases:
  * 1): @write_fault = true
  * 2): @write_fault = false && @writable, @writable will tell the caller
  *     whether the mapping is writable.
  */
 kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
              bool write_fault, bool *writable)
 {
     struct vm_area_struct *vma;
     kvm_pfn_t pfn;
     int npages, r;
 
     /* we can do it either atomically or asynchronously, not both */
     BUG_ON(atomic && async);
 
     if (hva_to_pfn_fast(addr, write_fault, writable, &pfn))
         return pfn;
 
     if (atomic)
         return KVM_PFN_ERR_FAULT;
 
     npages = hva_to_pfn_slow(addr, async, write_fault, writable, &pfn);
     if (npages == 1)
         return pfn;
 
     mmap_read_lock(current->mm);
     if (npages == -EHWPOISON ||
           (!async && check_user_page_hwpoison(addr))) {
         pfn = KVM_PFN_ERR_HWPOISON;
         goto exit;
     }
 
 retry:
     vma = vma_lookup(current->mm, addr);
 
     if (vma == NULL)
         pfn = KVM_PFN_ERR_FAULT;
     else if (vma->vm_flags & (VM_IO | VM_PFNMAP)) {
         r = hva_to_pfn_remapped(vma, addr, write_fault, writable, &pfn);
         if (r == -EAGAIN)
             goto retry;
         if (r < 0)
             pfn = KVM_PFN_ERR_FAULT;
     } else {
         if (async && vma_is_valid(vma, write_fault))
             *async = true;
         pfn = KVM_PFN_ERR_FAULT;
     }
 exit:
     mmap_read_unlock(current->mm);
     return pfn;
 }
 
 kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn,
                    bool atomic, bool *async, bool write_fault,
                    bool *writable, hva_t *hva)
 {
     unsigned long addr = __gfn_to_hva_many(slot, gfn, NULL, write_fault);
 
     if (hva)
         *hva = addr;
 
     if (addr == KVM_HVA_ERR_RO_BAD) {
         if (writable)
             *writable = false;
         return KVM_PFN_ERR_RO_FAULT;
     }
 
     if (kvm_is_error_hva(addr)) {
         if (writable)
             *writable = false;
         return KVM_PFN_NOSLOT;
     }
 
     /* Do not map writable pfn in the readonly memslot. */
     if (writable && memslot_is_readonly(slot)) {
         *writable = false;
         writable = NULL;
     }
 
     return hva_to_pfn(addr, atomic, async, write_fault,
               writable);
 }
 EXPORT_SYMBOL_GPL(__gfn_to_pfn_memslot);
 
 kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
               bool *writable)
 {
     return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn, false, NULL,
                     write_fault, writable, NULL);
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn_prot);
 
 kvm_pfn_t gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn)
 {
     return __gfn_to_pfn_memslot(slot, gfn, false, NULL, true, NULL, NULL);
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot);
 
 kvm_pfn_t gfn_to_pfn_memslot_atomic(const struct kvm_memory_slot *slot, gfn_t gfn)
 {
     return __gfn_to_pfn_memslot(slot, gfn, true, NULL, true, NULL, NULL);
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot_atomic);
 
 kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
     return gfn_to_pfn_memslot_atomic(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_pfn_atomic);
 
 kvm_pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
 {
     return gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn);
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn);
 
 kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
     return gfn_to_pfn_memslot(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_pfn);
 
 int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
                 struct page **pages, int nr_pages)
 {
     unsigned long addr;
     gfn_t entry = 0;
 
     addr = gfn_to_hva_many(slot, gfn, &entry);
     if (kvm_is_error_hva(addr))
         return -1;
 
     if (entry < nr_pages)
         return 0;
 
     return get_user_pages_fast_only(addr, nr_pages, FOLL_WRITE, pages);
 }
 EXPORT_SYMBOL_GPL(gfn_to_page_many_atomic);
 
 /*
  * Do not use this helper unless you are absolutely certain the gfn _must_ be
  * backed by 'struct page'.  A valid example is if the backing memslot is
  * controlled by KVM.  Note, if the returned page is valid, it's refcount has
  * been elevated by gfn_to_pfn().
  */
 struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
 {
     struct page *page;
     kvm_pfn_t pfn;
 
     pfn = gfn_to_pfn(kvm, gfn);
 
     if (is_error_noslot_pfn(pfn))
         return KVM_ERR_PTR_BAD_PAGE;
 
     page = kvm_pfn_to_refcounted_page(pfn);
     if (!page)
         return KVM_ERR_PTR_BAD_PAGE;
 
     return page;
 }
 EXPORT_SYMBOL_GPL(gfn_to_page);
 
 void kvm_release_pfn(kvm_pfn_t pfn, bool dirty)
 {
     if (dirty)
         kvm_release_pfn_dirty(pfn);
     else
         kvm_release_pfn_clean(pfn);
 }
 
 int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
 {
     kvm_pfn_t pfn;
     void *hva = NULL;
     struct page *page = KVM_UNMAPPED_PAGE;
 
     if (!map)
         return -EINVAL;
 
     pfn = gfn_to_pfn(vcpu->kvm, gfn);
     if (is_error_noslot_pfn(pfn))
         return -EINVAL;
 
     if (pfn_valid(pfn)) {
         page = pfn_to_page(pfn);
         hva = kmap(page);
 #ifdef CONFIG_HAS_IOMEM
     } else {
         hva = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
 #endif
     }
 
     if (!hva)
         return -EFAULT;
 
     map->page = page;
     map->hva = hva;
     map->pfn = pfn;
     map->gfn = gfn;
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_map);
 
 void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
 {
     if (!map)
         return;
 
     if (!map->hva)
         return;
 
     if (map->page != KVM_UNMAPPED_PAGE)
         kunmap(map->page);
 #ifdef CONFIG_HAS_IOMEM
     else
         memunmap(map->hva);
 #endif
 
     if (dirty)
         kvm_vcpu_mark_page_dirty(vcpu, map->gfn);
 
     kvm_release_pfn(map->pfn, dirty);
 
     map->hva = NULL;
     map->page = NULL;
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);
 
 static bool kvm_is_ad_tracked_page(struct page *page)
 {
     /*
      * Per page-flags.h, pages tagged PG_reserved "should in general not be
      * touched (e.g. set dirty) except by its owner".
      */
     return !PageReserved(page);
 }
 
 static void kvm_set_page_dirty(struct page *page)
 {
     if (kvm_is_ad_tracked_page(page))
         SetPageDirty(page);
 }
 
 static void kvm_set_page_accessed(struct page *page)
 {
     if (kvm_is_ad_tracked_page(page))
         mark_page_accessed(page);
 }
 
 void kvm_release_page_clean(struct page *page)
 {
     WARN_ON(is_error_page(page));
 
     kvm_set_page_accessed(page);
     put_page(page);
 }
 EXPORT_SYMBOL_GPL(kvm_release_page_clean);
 
 void kvm_release_pfn_clean(kvm_pfn_t pfn)
 {
     struct page *page;
 
     if (is_error_noslot_pfn(pfn))
         return;
 
     page = kvm_pfn_to_refcounted_page(pfn);
     if (!page)
         return;
 
     kvm_release_page_clean(page);
 }
 EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);
 
 void kvm_release_page_dirty(struct page *page)
 {
     WARN_ON(is_error_page(page));
 
     kvm_set_page_dirty(page);
     kvm_release_page_clean(page);
 }
 EXPORT_SYMBOL_GPL(kvm_release_page_dirty);
 
 void kvm_release_pfn_dirty(kvm_pfn_t pfn)
 {
     struct page *page;
 
     if (is_error_noslot_pfn(pfn))
         return;
 
     page = kvm_pfn_to_refcounted_page(pfn);
     if (!page)
         return;
 
     kvm_release_page_dirty(page);
 }
 EXPORT_SYMBOL_GPL(kvm_release_pfn_dirty);
 
 /*
  * Note, checking for an error/noslot pfn is the caller's responsibility when
  * directly marking a page dirty/accessed.  Unlike the "release" helpers, the
  * "set" helpers are not to be used when the pfn might point at garbage.
  */
 void kvm_set_pfn_dirty(kvm_pfn_t pfn)
 {
     if (WARN_ON(is_error_noslot_pfn(pfn)))
         return;
 
     if (pfn_valid(pfn))
         kvm_set_page_dirty(pfn_to_page(pfn));
 }
 EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty);
 
 void kvm_set_pfn_accessed(kvm_pfn_t pfn)
 {
     if (WARN_ON(is_error_noslot_pfn(pfn)))
         return;
 
     if (pfn_valid(pfn))
         kvm_set_page_accessed(pfn_to_page(pfn));
 }
 EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed);
 
 static int next_segment(unsigned long len, int offset)
 {
     if (len > PAGE_SIZE - offset)
         return PAGE_SIZE - offset;
     else
         return len;
 }
 
 static int __kvm_read_guest_page(struct kvm_memory_slot *slot, gfn_t gfn,
                  void *data, int offset, int len)
 {
     int r;
     unsigned long addr;
 
     addr = gfn_to_hva_memslot_prot(slot, gfn, NULL);
     if (kvm_is_error_hva(addr))
         return -EFAULT;
     r = __copy_from_user(data, (void __user *)addr + offset, len);
     if (r)
         return -EFAULT;
     return 0;
 }
 
 int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
             int len)
 {
     struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
 
     return __kvm_read_guest_page(slot, gfn, data, offset, len);
 }
 EXPORT_SYMBOL_GPL(kvm_read_guest_page);
 
 int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data,
                  int offset, int len)
 {
     struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
 
     return __kvm_read_guest_page(slot, gfn, data, offset, len);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest_page);
 
 int kvm_read_guest(struct kvm *kvm, gpa_t gpa, void *data, unsigned long len)
 {
     gfn_t gfn = gpa >> PAGE_SHIFT;
     int seg;
     int offset = offset_in_page(gpa);
     int ret;
 
     while ((seg = next_segment(len, offset)) != 0) {
         ret = kvm_read_guest_page(kvm, gfn, data, offset, seg);
         if (ret < 0)
             return ret;
         offset = 0;
         len -= seg;
         data += seg;
         ++gfn;
     }
     return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_read_guest);
 
 int kvm_vcpu_read_guest(struct kvm_vcpu *vcpu, gpa_t gpa, void *data, unsigned long len)
 {
     gfn_t gfn = gpa >> PAGE_SHIFT;
     int seg;
     int offset = offset_in_page(gpa);
     int ret;
 
     while ((seg = next_segment(len, offset)) != 0) {
         ret = kvm_vcpu_read_guest_page(vcpu, gfn, data, offset, seg);
         if (ret < 0)
             return ret;
         offset = 0;
         len -= seg;
         data += seg;
         ++gfn;
     }
     return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest);
 
 static int __kvm_read_guest_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
                        void *data, int offset, unsigned long len)
 {
     int r;
     unsigned long addr;
 
     addr = gfn_to_hva_memslot_prot(slot, gfn, NULL);
     if (kvm_is_error_hva(addr))
         return -EFAULT;
     pagefault_disable();
     r = __copy_from_user_inatomic(data, (void __user *)addr + offset, len);
     pagefault_enable();
     if (r)
         return -EFAULT;
     return 0;
 }
 
 int kvm_vcpu_read_guest_atomic(struct kvm_vcpu *vcpu, gpa_t gpa,
                    void *data, unsigned long len)
 {
     gfn_t gfn = gpa >> PAGE_SHIFT;
     struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
     int offset = offset_in_page(gpa);
 
     return __kvm_read_guest_atomic(slot, gfn, data, offset, len);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest_atomic);
 
 static int __kvm_write_guest_page(struct kvm *kvm,
                   struct kvm_memory_slot *memslot, gfn_t gfn,
                       const void *data, int offset, int len)
 {
     int r;
     unsigned long addr;
 
     addr = gfn_to_hva_memslot(memslot, gfn);
     if (kvm_is_error_hva(addr))
         return -EFAULT;
     r = __copy_to_user((void __user *)addr + offset, data, len);
     if (r)
         return -EFAULT;
     mark_page_dirty_in_slot(kvm, memslot, gfn);
     return 0;
 }
 
 int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn,
              const void *data, int offset, int len)
 {
     struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
 
     return __kvm_write_guest_page(kvm, slot, gfn, data, offset, len);
 }
 EXPORT_SYMBOL_GPL(kvm_write_guest_page);
 
 int kvm_vcpu_write_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn,
                   const void *data, int offset, int len)
 {
     struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
 
     return __kvm_write_guest_page(vcpu->kvm, slot, gfn, data, offset, len);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_write_guest_page);
 
 int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
             unsigned long len)
 {
     gfn_t gfn = gpa >> PAGE_SHIFT;
     int seg;
     int offset = offset_in_page(gpa);
     int ret;
 
     while ((seg = next_segment(len, offset)) != 0) {
         ret = kvm_write_guest_page(kvm, gfn, data, offset, seg);
         if (ret < 0)
             return ret;
         offset = 0;
         len -= seg;
         data += seg;
         ++gfn;
     }
     return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_write_guest);
 
 int kvm_vcpu_write_guest(struct kvm_vcpu *vcpu, gpa_t gpa, const void *data,
                  unsigned long len)
 {
     gfn_t gfn = gpa >> PAGE_SHIFT;
     int seg;
     int offset = offset_in_page(gpa);
     int ret;
 
     while ((seg = next_segment(len, offset)) != 0) {
         ret = kvm_vcpu_write_guest_page(vcpu, gfn, data, offset, seg);
         if (ret < 0)
             return ret;
         offset = 0;
         len -= seg;
         data += seg;
         ++gfn;
     }
     return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_write_guest);
 
 static int __kvm_gfn_to_hva_cache_init(struct kvm_memslots *slots,
                        struct gfn_to_hva_cache *ghc,
                        gpa_t gpa, unsigned long len)
 {
     int offset = offset_in_page(gpa);
     gfn_t start_gfn = gpa >> PAGE_SHIFT;
     gfn_t end_gfn = (gpa + len - 1) >> PAGE_SHIFT;
     gfn_t nr_pages_needed = end_gfn - start_gfn + 1;
     gfn_t nr_pages_avail;
 
     /* Update ghc->generation before performing any error checks. */
     ghc->generation = slots->generation;
 
     if (start_gfn > end_gfn) {
         ghc->hva = KVM_HVA_ERR_BAD;
         return -EINVAL;
     }
 
     /*
      * If the requested region crosses two memslots, we still
      * verify that the entire region is valid here.
      */
     for ( ; start_gfn <= end_gfn; start_gfn += nr_pages_avail) {
         ghc->memslot = __gfn_to_memslot(slots, start_gfn);
         ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn,
                        &nr_pages_avail);
         if (kvm_is_error_hva(ghc->hva))
             return -EFAULT;
     }
 
     /* Use the slow path for cross page reads and writes. */
     if (nr_pages_needed == 1)
         ghc->hva += offset;
     else
         ghc->memslot = NULL;
 
     ghc->gpa = gpa;
     ghc->len = len;
     return 0;
 }
 
 int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
                   gpa_t gpa, unsigned long len)
 {
     struct kvm_memslots *slots = kvm_memslots(kvm);
     return __kvm_gfn_to_hva_cache_init(slots, ghc, gpa, len);
 }
 EXPORT_SYMBOL_GPL(kvm_gfn_to_hva_cache_init);
 
 int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
                   void *data, unsigned int offset,
                   unsigned long len)
 {
     struct kvm_memslots *slots = kvm_memslots(kvm);
     int r;
     gpa_t gpa = ghc->gpa + offset;
 
     if (WARN_ON_ONCE(len + offset > ghc->len))
         return -EINVAL;
 
     if (slots->generation != ghc->generation) {
         if (__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len))
             return -EFAULT;
     }
 
     if (kvm_is_error_hva(ghc->hva))
         return -EFAULT;
 
     if (unlikely(!ghc->memslot))
         return kvm_write_guest(kvm, gpa, data, len);
 
     r = __copy_to_user((void __user *)ghc->hva + offset, data, len);
     if (r)
         return -EFAULT;
     mark_page_dirty_in_slot(kvm, ghc->memslot, gpa >> PAGE_SHIFT);
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_write_guest_offset_cached);
 
 int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
                void *data, unsigned long len)
 {
     return kvm_write_guest_offset_cached(kvm, ghc, data, 0, len);
 }
 EXPORT_SYMBOL_GPL(kvm_write_guest_cached);
 
 int kvm_read_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
                  void *data, unsigned int offset,
                  unsigned long len)
 {
     struct kvm_memslots *slots = kvm_memslots(kvm);
     int r;
     gpa_t gpa = ghc->gpa + offset;
 
     if (WARN_ON_ONCE(len + offset > ghc->len))
         return -EINVAL;
 
     if (slots->generation != ghc->generation) {
         if (__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len))
             return -EFAULT;
     }
 
     if (kvm_is_error_hva(ghc->hva))
         return -EFAULT;
 
     if (unlikely(!ghc->memslot))
         return kvm_read_guest(kvm, gpa, data, len);
 
     r = __copy_from_user(data, (void __user *)ghc->hva + offset, len);
     if (r)
         return -EFAULT;
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_read_guest_offset_cached);
 
 int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
               void *data, unsigned long len)
 {
     return kvm_read_guest_offset_cached(kvm, ghc, data, 0, len);
 }
 EXPORT_SYMBOL_GPL(kvm_read_guest_cached);
 
 int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len)
 {
     const void *zero_page = (const void *) __va(page_to_phys(ZERO_PAGE(0)));
     gfn_t gfn = gpa >> PAGE_SHIFT;
     int seg;
     int offset = offset_in_page(gpa);
     int ret;
 
     while ((seg = next_segment(len, offset)) != 0) {
         ret = kvm_write_guest_page(kvm, gfn, zero_page, offset, len);
         if (ret < 0)
             return ret;
         offset = 0;
         len -= seg;
         ++gfn;
     }
     return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_clear_guest);
 
 void mark_page_dirty_in_slot(struct kvm *kvm,
                  const struct kvm_memory_slot *memslot,
                  gfn_t gfn)
 {
     struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
 #ifdef CONFIG_HAVE_KVM_DIRTY_RING
     if (WARN_ON_ONCE(!vcpu) || WARN_ON_ONCE(vcpu->kvm != kvm))
         return;
 #endif
 
     if (memslot && kvm_slot_dirty_track_enabled(memslot)) {
         unsigned long rel_gfn = gfn - memslot->base_gfn;
         u32 slot = (memslot->as_id << 16) | memslot->id;
 
         if (kvm->dirty_ring_size)
             kvm_dirty_ring_push(&vcpu->dirty_ring,
                         slot, rel_gfn);
         else
             set_bit_le(rel_gfn, memslot->dirty_bitmap);
     }
 }
 EXPORT_SYMBOL_GPL(mark_page_dirty_in_slot);
 
 void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
 {
     struct kvm_memory_slot *memslot;
 
     memslot = gfn_to_memslot(kvm, gfn);
     mark_page_dirty_in_slot(kvm, memslot, gfn);
 }
 EXPORT_SYMBOL_GPL(mark_page_dirty);
 
 void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
     struct kvm_memory_slot *memslot;
 
     memslot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
     mark_page_dirty_in_slot(vcpu->kvm, memslot, gfn);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_mark_page_dirty);
 
 void kvm_sigset_activate(struct kvm_vcpu *vcpu)
 {
     if (!vcpu->sigset_active)
         return;
 
     /*
      * This does a lockless modification of ->real_blocked, which is fine
      * because, only current can change ->real_blocked and all readers of
      * ->real_blocked don't care as long ->real_blocked is always a subset
      * of ->blocked.
      */
     sigprocmask(SIG_SETMASK, &vcpu->sigset, &current->real_blocked);
 }
 
 void kvm_sigset_deactivate(struct kvm_vcpu *vcpu)
 {
     if (!vcpu->sigset_active)
         return;
 
     sigprocmask(SIG_SETMASK, &current->real_blocked, NULL);
     sigemptyset(&current->real_blocked);
 }
 
 static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
 {
     unsigned int old, val, grow, grow_start;
 
     old = val = vcpu->halt_poll_ns;
     grow_start = READ_ONCE(halt_poll_ns_grow_start);
     grow = READ_ONCE(halt_poll_ns_grow);
     if (!grow)
         goto out;
 
     val *= grow;
     if (val < grow_start)
         val = grow_start;
 
     if (val > vcpu->kvm->max_halt_poll_ns)
         val = vcpu->kvm->max_halt_poll_ns;
 
     vcpu->halt_poll_ns = val;
 out:
     trace_kvm_halt_poll_ns_grow(vcpu->vcpu_id, val, old);
 }
 
 static void shrink_halt_poll_ns(struct kvm_vcpu *vcpu)
 {
     unsigned int old, val, shrink, grow_start;
 
     old = val = vcpu->halt_poll_ns;
     shrink = READ_ONCE(halt_poll_ns_shrink);
     grow_start = READ_ONCE(halt_poll_ns_grow_start);
     if (shrink == 0)
         val = 0;
     else
         val /= shrink;
 
     if (val < grow_start)
         val = 0;
 
     vcpu->halt_poll_ns = val;
     trace_kvm_halt_poll_ns_shrink(vcpu->vcpu_id, val, old);
 }
 
 static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu)
 {
     int ret = -EINTR;
     int idx = srcu_read_lock(&vcpu->kvm->srcu);
 
     if (kvm_arch_vcpu_runnable(vcpu)) {
         kvm_make_request(KVM_REQ_UNHALT, vcpu);
         goto out;
     }
     if (kvm_cpu_has_pending_timer(vcpu))
         goto out;
     if (signal_pending(current))
         goto out;
     if (kvm_check_request(KVM_REQ_UNBLOCK, vcpu))
         goto out;
 
     ret = 0;
 out:
     srcu_read_unlock(&vcpu->kvm->srcu, idx);
     return ret;
 }
 
 /*
  * Block the vCPU until the vCPU is runnable, an event arrives, or a signal is
  * pending.  This is mostly used when halting a vCPU, but may also be used
  * directly for other vCPU non-runnable states, e.g. x86's Wait-For-SIPI.
  */
 bool kvm_vcpu_block(struct kvm_vcpu *vcpu)
 {
     struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
     bool waited = false;
 
     vcpu->stat.generic.blocking = 1;
 
     preempt_disable();
     kvm_arch_vcpu_blocking(vcpu);
     prepare_to_rcuwait(wait);
     preempt_enable();
 
     for (;;) {
         set_current_state(TASK_INTERRUPTIBLE);
 
         if (kvm_vcpu_check_block(vcpu) < 0)
             break;
 
         waited = true;
         schedule();
     }
 
     preempt_disable();
     finish_rcuwait(wait);
     kvm_arch_vcpu_unblocking(vcpu);
     preempt_enable();
 
     vcpu->stat.generic.blocking = 0;
 
     return waited;
 }
 
 static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start,
                       ktime_t end, bool success)
 {
     struct kvm_vcpu_stat_generic *stats = &vcpu->stat.generic;
     u64 poll_ns = ktime_to_ns(ktime_sub(end, start));
 
     ++vcpu->stat.generic.halt_attempted_poll;
 
     if (success) {
         ++vcpu->stat.generic.halt_successful_poll;
 
         if (!vcpu_valid_wakeup(vcpu))
             ++vcpu->stat.generic.halt_poll_invalid;
 
         stats->halt_poll_success_ns += poll_ns;
         KVM_STATS_LOG_HIST_UPDATE(stats->halt_poll_success_hist, poll_ns);
     } else {
         stats->halt_poll_fail_ns += poll_ns;
         KVM_STATS_LOG_HIST_UPDATE(stats->halt_poll_fail_hist, poll_ns);
     }
 }
 
 /*
  * Emulate a vCPU halt condition, e.g. HLT on x86, WFI on arm, etc...  If halt
  * polling is enabled, busy wait for a short time before blocking to avoid the
  * expensive block+unblock sequence if a wake event arrives soon after the vCPU
  * is halted.
  */
 void kvm_vcpu_halt(struct kvm_vcpu *vcpu)
 {
     bool halt_poll_allowed = !kvm_arch_no_poll(vcpu);
     bool do_halt_poll = halt_poll_allowed && vcpu->halt_poll_ns;
     ktime_t start, cur, poll_end;
     bool waited = false;
     u64 halt_ns;
 
     start = cur = poll_end = ktime_get();
     if (do_halt_poll) {
         ktime_t stop = ktime_add_ns(start, vcpu->halt_poll_ns);
 
         do {
             /*
              * This sets KVM_REQ_UNHALT if an interrupt
              * arrives.
              */
             if (kvm_vcpu_check_block(vcpu) < 0)
                 goto out;
             cpu_relax();
             poll_end = cur = ktime_get();
         } while (kvm_vcpu_can_poll(cur, stop));
     }
 
     waited = kvm_vcpu_block(vcpu);
 
     cur = ktime_get();
     if (waited) {
         vcpu->stat.generic.halt_wait_ns +=
             ktime_to_ns(cur) - ktime_to_ns(poll_end);
         KVM_STATS_LOG_HIST_UPDATE(vcpu->stat.generic.halt_wait_hist,
                 ktime_to_ns(cur) - ktime_to_ns(poll_end));
     }
 out:
     /* The total time the vCPU was "halted", including polling time. */
     halt_ns = ktime_to_ns(cur) - ktime_to_ns(start);
 
     /*
      * Note, halt-polling is considered successful so long as the vCPU was
      * never actually scheduled out, i.e. even if the wake event arrived
      * after of the halt-polling loop itself, but before the full wait.
      */
     if (do_halt_poll)
         update_halt_poll_stats(vcpu, start, poll_end, !waited);
 
     if (halt_poll_allowed) {
         if (!vcpu_valid_wakeup(vcpu)) {
             shrink_halt_poll_ns(vcpu);
         } else if (vcpu->kvm->max_halt_poll_ns) {
             if (halt_ns <= vcpu->halt_poll_ns)
                 ;
             /* we had a long block, shrink polling */
             else if (vcpu->halt_poll_ns &&
                  halt_ns > vcpu->kvm->max_halt_poll_ns)
                 shrink_halt_poll_ns(vcpu);
             /* we had a short halt and our poll time is too small */
             else if (vcpu->halt_poll_ns < vcpu->kvm->max_halt_poll_ns &&
                  halt_ns < vcpu->kvm->max_halt_poll_ns)
                 grow_halt_poll_ns(vcpu);
         } else {
             vcpu->halt_poll_ns = 0;
         }
     }
 
     trace_kvm_vcpu_wakeup(halt_ns, waited, vcpu_valid_wakeup(vcpu));
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_halt);
 
 bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu)
 {
     if (__kvm_vcpu_wake_up(vcpu)) {
         WRITE_ONCE(vcpu->ready, true);
         ++vcpu->stat.generic.halt_wakeup;
         return true;
     }
 
     return false;
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_wake_up);
 
 #ifndef CONFIG_S390
 /*
  * Kick a sleeping VCPU, or a guest VCPU in guest mode, into host kernel mode.
  */
 void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
 {
     int me, cpu;
 
     if (kvm_vcpu_wake_up(vcpu))
         return;
 
     me = get_cpu();
     /*
      * The only state change done outside the vcpu mutex is IN_GUEST_MODE
      * to EXITING_GUEST_MODE.  Therefore the moderately expensive "should
      * kick" check does not need atomic operations if kvm_vcpu_kick is used
      * within the vCPU thread itself.
      */
     if (vcpu == __this_cpu_read(kvm_running_vcpu)) {
         if (vcpu->mode == IN_GUEST_MODE)
             WRITE_ONCE(vcpu->mode, EXITING_GUEST_MODE);
         goto out;
     }
 
     /*
      * Note, the vCPU could get migrated to a different pCPU at any point
      * after kvm_arch_vcpu_should_kick(), which could result in sending an
      * IPI to the previous pCPU.  But, that's ok because the purpose of the
      * IPI is to force the vCPU to leave IN_GUEST_MODE, and migrating the
      * vCPU also requires it to leave IN_GUEST_MODE.
      */
     if (kvm_arch_vcpu_should_kick(vcpu)) {
         cpu = READ_ONCE(vcpu->cpu);
         if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu))
             smp_send_reschedule(cpu);
     }
 out:
     put_cpu();
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_kick);
 #endif /* !CONFIG_S390 */
 
 int kvm_vcpu_yield_to(struct kvm_vcpu *target)
 {
     struct pid *pid;
     struct task_struct *task = NULL;
     int ret = 0;
 
     rcu_read_lock();
     pid = rcu_dereference(target->pid);
     if (pid)
         task = get_pid_task(pid, PIDTYPE_PID);
     rcu_read_unlock();
     if (!task)
         return ret;
     ret = yield_to(task, 1);
     put_task_struct(task);
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_yield_to);
 
 /*
  * Helper that checks whether a VCPU is eligible for directed yield.
  * Most eligible candidate to yield is decided by following heuristics:
  *
  *  (a) VCPU which has not done pl-exit or cpu relax intercepted recently
  *  (preempted lock holder), indicated by @in_spin_loop.
  *  Set at the beginning and cleared at the end of interception/PLE handler.
  *
  *  (b) VCPU which has done pl-exit/ cpu relax intercepted but did not get
  *  chance last time (mostly it has become eligible now since we have probably
  *  yielded to lockholder in last iteration. This is done by toggling
  *  @dy_eligible each time a VCPU checked for eligibility.)
  *
  *  Yielding to a recently pl-exited/cpu relax intercepted VCPU before yielding
  *  to preempted lock-holder could result in wrong VCPU selection and CPU
  *  burning. Giving priority for a potential lock-holder increases lock
  *  progress.
  *
  *  Since algorithm is based on heuristics, accessing another VCPU data without
  *  locking does not harm. It may result in trying to yield to  same VCPU, fail
  *  and continue with next VCPU and so on.
  */
 static bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu)
 {
 #ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
     bool eligible;
 
     eligible = !vcpu->spin_loop.in_spin_loop ||
             vcpu->spin_loop.dy_eligible;
 
     if (vcpu->spin_loop.in_spin_loop)
         kvm_vcpu_set_dy_eligible(vcpu, !vcpu->spin_loop.dy_eligible);
 
     return eligible;
 #else
     return true;
 #endif
 }
 
 /*
  * Unlike kvm_arch_vcpu_runnable, this function is called outside
  * a vcpu_load/vcpu_put pair.  However, for most architectures
  * kvm_arch_vcpu_runnable does not require vcpu_load.
  */
 bool __weak kvm_arch_dy_runnable(struct kvm_vcpu *vcpu)
 {
     return kvm_arch_vcpu_runnable(vcpu);
 }
 
 static bool vcpu_dy_runnable(struct kvm_vcpu *vcpu)
 {
     if (kvm_arch_dy_runnable(vcpu))
         return true;
 
 #ifdef CONFIG_KVM_ASYNC_PF
     if (!list_empty_careful(&vcpu->async_pf.done))
         return true;
 #endif
 
     return false;
 }
 
 bool __weak kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu *vcpu)
 {
     return false;
 }
 
 void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode)
 {
     struct kvm *kvm = me->kvm;
     struct kvm_vcpu *vcpu;
     int last_boosted_vcpu = me->kvm->last_boosted_vcpu;
     unsigned long i;
     int yielded = 0;
     int try = 3;
     int pass;
 
     kvm_vcpu_set_in_spin_loop(me, true);
     /*
      * We boost the priority of a VCPU that is runnable but not
      * currently running, because it got preempted by something
      * else and called schedule in __vcpu_run.  Hopefully that
      * VCPU is holding the lock that we need and will release it.
      * We approximate round-robin by starting at the last boosted VCPU.
      */
     for (pass = 0; pass < 2 && !yielded && try; pass++) {
         kvm_for_each_vcpu(i, vcpu, kvm) {
             if (!pass && i <= last_boosted_vcpu) {
                 i = last_boosted_vcpu;
                 continue;
             } else if (pass && i > last_boosted_vcpu)
                 break;
             if (!READ_ONCE(vcpu->ready))
                 continue;
             if (vcpu == me)
                 continue;
             if (kvm_vcpu_is_blocking(vcpu) && !vcpu_dy_runnable(vcpu))
                 continue;
             if (READ_ONCE(vcpu->preempted) && yield_to_kernel_mode &&
                 !kvm_arch_dy_has_pending_interrupt(vcpu) &&
                 !kvm_arch_vcpu_in_kernel(vcpu))
                 continue;
             if (!kvm_vcpu_eligible_for_directed_yield(vcpu))
                 continue;
 
             yielded = kvm_vcpu_yield_to(vcpu);
             if (yielded > 0) {
                 kvm->last_boosted_vcpu = i;
                 break;
             } else if (yielded < 0) {
                 try--;
                 if (!try)
                     break;
             }
         }
     }
     kvm_vcpu_set_in_spin_loop(me, false);
 
     /* Ensure vcpu is not eligible during next spinloop */
     kvm_vcpu_set_dy_eligible(me, false);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_on_spin);
 
 static bool kvm_page_in_dirty_ring(struct kvm *kvm, unsigned long pgoff)
 {
 #ifdef CONFIG_HAVE_KVM_DIRTY_RING
     return (pgoff >= KVM_DIRTY_LOG_PAGE_OFFSET) &&
         (pgoff < KVM_DIRTY_LOG_PAGE_OFFSET +
          kvm->dirty_ring_size / PAGE_SIZE);
 #else
     return false;
 #endif
 }
 
 static vm_fault_t kvm_vcpu_fault(struct vm_fault *vmf)
 {
     struct kvm_vcpu *vcpu = vmf->vma->vm_file->private_data;
     struct page *page;
 
     if (vmf->pgoff == 0)
         page = virt_to_page(vcpu->run);
 #ifdef CONFIG_X86
     else if (vmf->pgoff == KVM_PIO_PAGE_OFFSET)
         page = virt_to_page(vcpu->arch.pio_data);
 #endif
 #ifdef CONFIG_KVM_MMIO
     else if (vmf->pgoff == KVM_COALESCED_MMIO_PAGE_OFFSET)
         page = virt_to_page(vcpu->kvm->coalesced_mmio_ring);
 #endif
     else if (kvm_page_in_dirty_ring(vcpu->kvm, vmf->pgoff))
         page = kvm_dirty_ring_get_page(
             &vcpu->dirty_ring,
             vmf->pgoff - KVM_DIRTY_LOG_PAGE_OFFSET);
     else
         return kvm_arch_vcpu_fault(vcpu, vmf);
     get_page(page);
     vmf->page = page;
     return 0;
 }
 
 static const struct vm_operations_struct kvm_vcpu_vm_ops = {
     .fault = kvm_vcpu_fault,
 };
 
 static int kvm_vcpu_mmap(struct file *file, struct vm_area_struct *vma)
 {
     struct kvm_vcpu *vcpu = file->private_data;
     unsigned long pages = vma_pages(vma);
 
     if ((kvm_page_in_dirty_ring(vcpu->kvm, vma->vm_pgoff) ||
          kvm_page_in_dirty_ring(vcpu->kvm, vma->vm_pgoff + pages - 1)) &&
         ((vma->vm_flags & VM_EXEC) || !(vma->vm_flags & VM_SHARED)))
         return -EINVAL;
 
     vma->vm_ops = &kvm_vcpu_vm_ops;
     return 0;
 }
 
 static int kvm_vcpu_release(struct inode *inode, struct file *filp)
 {
     struct kvm_vcpu *vcpu = filp->private_data;
 
     kvm_put_kvm(vcpu->kvm);
     return 0;
 }
 
 static const struct file_operations kvm_vcpu_fops = {
     .release        = kvm_vcpu_release,
     .unlocked_ioctl = kvm_vcpu_ioctl,
     .mmap           = kvm_vcpu_mmap,
     .llseek     = noop_llseek,
     KVM_COMPAT(kvm_vcpu_compat_ioctl),
 };
 
 /*
  * Allocates an inode for the vcpu.
  */
 static int create_vcpu_fd(struct kvm_vcpu *vcpu)
 {
     char name[8 + 1 + ITOA_MAX_LEN + 1];
 
     snprintf(name, sizeof(name), "kvm-vcpu:%d", vcpu->vcpu_id);
     return anon_inode_getfd(name, &kvm_vcpu_fops, vcpu, O_RDWR | O_CLOEXEC);
 }
 
 #ifdef __KVM_HAVE_ARCH_VCPU_DEBUGFS
 static int vcpu_get_pid(void *data, u64 *val)
 {
     struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
     *val = pid_nr(rcu_access_pointer(vcpu->pid));
     return 0;
 }
 
 DEFINE_SIMPLE_ATTRIBUTE(vcpu_get_pid_fops, vcpu_get_pid, NULL, "%llu\n");
 
 static void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
 {
     struct dentry *debugfs_dentry;
     char dir_name[ITOA_MAX_LEN * 2];
 
     if (!debugfs_initialized())
         return;
 
     snprintf(dir_name, sizeof(dir_name), "vcpu%d", vcpu->vcpu_id);
     debugfs_dentry = debugfs_create_dir(dir_name,
                         vcpu->kvm->debugfs_dentry);
     debugfs_create_file("pid", 0444, debugfs_dentry, vcpu,
                 &vcpu_get_pid_fops);
 
     kvm_arch_create_vcpu_debugfs(vcpu, debugfs_dentry);
 }
 #endif
 
 /*
  * Creates some virtual cpus.  Good luck creating more than one.
  */
 static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 {
     int r;
     struct kvm_vcpu *vcpu;
     struct page *page;
 
     if (id >= KVM_MAX_VCPU_IDS)
         return -EINVAL;
 
     mutex_lock(&kvm->lock);
     if (kvm->created_vcpus >= kvm->max_vcpus) {
         mutex_unlock(&kvm->lock);
         return -EINVAL;
     }
 
     r = kvm_arch_vcpu_precreate(kvm, id);
     if (r) {
         mutex_unlock(&kvm->lock);
         return r;
     }
 
     kvm->created_vcpus++;
     mutex_unlock(&kvm->lock);
 
     vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL_ACCOUNT);
     if (!vcpu) {
         r = -ENOMEM;
         goto vcpu_decrement;
     }
 
     BUILD_BUG_ON(sizeof(struct kvm_run) > PAGE_SIZE);
     page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
     if (!page) {
         r = -ENOMEM;
         goto vcpu_free;
     }
     vcpu->run = page_address(page);
 
     kvm_vcpu_init(vcpu, kvm, id);
 
     r = kvm_arch_vcpu_create(vcpu);
     if (r)
         goto vcpu_free_run_page;
 
     if (kvm->dirty_ring_size) {
         r = kvm_dirty_ring_alloc(&vcpu->dirty_ring,
                      id, kvm->dirty_ring_size);
         if (r)
             goto arch_vcpu_destroy;
     }
 
     mutex_lock(&kvm->lock);
     if (kvm_get_vcpu_by_id(kvm, id)) {
         r = -EEXIST;
         goto unlock_vcpu_destroy;
     }
 
     vcpu->vcpu_idx = atomic_read(&kvm->online_vcpus);
     r = xa_insert(&kvm->vcpu_array, vcpu->vcpu_idx, vcpu, GFP_KERNEL_ACCOUNT);
     BUG_ON(r == -EBUSY);
     if (r)
         goto unlock_vcpu_destroy;
 
     /* Now it's all set up, let userspace reach it */
     kvm_get_kvm(kvm);
     r = create_vcpu_fd(vcpu);
     if (r < 0) {
         xa_erase(&kvm->vcpu_array, vcpu->vcpu_idx);
         kvm_put_kvm_no_destroy(kvm);
         goto unlock_vcpu_destroy;
     }
 
     /*
      * Pairs with smp_rmb() in kvm_get_vcpu.  Store the vcpu
      * pointer before kvm->online_vcpu's incremented value.
      */
     smp_wmb();
     atomic_inc(&kvm->online_vcpus);
 
     mutex_unlock(&kvm->lock);
     kvm_arch_vcpu_postcreate(vcpu);
     kvm_create_vcpu_debugfs(vcpu);
     return r;
 
 unlock_vcpu_destroy:
     mutex_unlock(&kvm->lock);
     kvm_dirty_ring_free(&vcpu->dirty_ring);
 arch_vcpu_destroy:
     kvm_arch_vcpu_destroy(vcpu);
 vcpu_free_run_page:
     free_page((unsigned long)vcpu->run);
 vcpu_free:
     kmem_cache_free(kvm_vcpu_cache, vcpu);
 vcpu_decrement:
     mutex_lock(&kvm->lock);
     kvm->created_vcpus--;
     mutex_unlock(&kvm->lock);
     return r;
 }
 
 static int kvm_vcpu_ioctl_set_sigmask(struct kvm_vcpu *vcpu, sigset_t *sigset)
 {
     if (sigset) {
         sigdelsetmask(sigset, sigmask(SIGKILL)|sigmask(SIGSTOP));
         vcpu->sigset_active = 1;
         vcpu->sigset = *sigset;
     } else
         vcpu->sigset_active = 0;
     return 0;
 }
 
 static ssize_t kvm_vcpu_stats_read(struct file *file, char __user *user_buffer,
                   size_t size, loff_t *offset)
 {
     struct kvm_vcpu *vcpu = file->private_data;
 
     return kvm_stats_read(vcpu->stats_id, &kvm_vcpu_stats_header,
             &kvm_vcpu_stats_desc[0], &vcpu->stat,
             sizeof(vcpu->stat), user_buffer, size, offset);
 }
 
 static const struct file_operations kvm_vcpu_stats_fops = {
     .read = kvm_vcpu_stats_read,
     .llseek = noop_llseek,
 };
 
 static int kvm_vcpu_ioctl_get_stats_fd(struct kvm_vcpu *vcpu)
 {
     int fd;
     struct file *file;
     char name[15 + ITOA_MAX_LEN + 1];
 
     snprintf(name, sizeof(name), "kvm-vcpu-stats:%d", vcpu->vcpu_id);
 
     fd = get_unused_fd_flags(O_CLOEXEC);
     if (fd < 0)
         return fd;
 
     file = anon_inode_getfile(name, &kvm_vcpu_stats_fops, vcpu, O_RDONLY);
     if (IS_ERR(file)) {
         put_unused_fd(fd);
         return PTR_ERR(file);
     }
     file->f_mode |= FMODE_PREAD;
     fd_install(fd, file);
 
     return fd;
 }
 
 static long kvm_vcpu_ioctl(struct file *filp,
                unsigned int ioctl, unsigned long arg)
 {
     struct kvm_vcpu *vcpu = filp->private_data;
     void __user *argp = (void __user *)arg;
     int r;
     struct kvm_fpu *fpu = NULL;
     struct kvm_sregs *kvm_sregs = NULL;
 
     if (vcpu->kvm->mm != current->mm || vcpu->kvm->vm_dead)
         return -EIO;
 
     if (unlikely(_IOC_TYPE(ioctl) != KVMIO))
         return -EINVAL;
 
     /*
      * Some architectures have vcpu ioctls that are asynchronous to vcpu
      * execution; mutex_lock() would break them.
      */
     r = kvm_arch_vcpu_async_ioctl(filp, ioctl, arg);
     if (r != -ENOIOCTLCMD)
         return r;
 
     if (mutex_lock_killable(&vcpu->mutex))
         return -EINTR;
     switch (ioctl) {
     case KVM_RUN: {
         struct pid *oldpid;
         r = -EINVAL;
         if (arg)
             goto out;
         oldpid = rcu_access_pointer(vcpu->pid);
         if (unlikely(oldpid != task_pid(current))) {
             /* The thread running this VCPU changed. */
             struct pid *newpid;
 
             r = kvm_arch_vcpu_run_pid_change(vcpu);
             if (r)
                 break;
 
             newpid = get_task_pid(current, PIDTYPE_PID);
             rcu_assign_pointer(vcpu->pid, newpid);
             if (oldpid)
                 synchronize_rcu();
             put_pid(oldpid);
         }
         r = kvm_arch_vcpu_ioctl_run(vcpu);
         trace_kvm_userspace_exit(vcpu->run->exit_reason, r);
         break;
     }
     case KVM_GET_REGS: {
         struct kvm_regs *kvm_regs;
 
         r = -ENOMEM;
         kvm_regs = kzalloc(sizeof(struct kvm_regs), GFP_KERNEL_ACCOUNT);
         if (!kvm_regs)
             goto out;
         r = kvm_arch_vcpu_ioctl_get_regs(vcpu, kvm_regs);
         if (r)
             goto out_free1;
         r = -EFAULT;
         if (copy_to_user(argp, kvm_regs, sizeof(struct kvm_regs)))
             goto out_free1;
         r = 0;
 out_free1:
         kfree(kvm_regs);
         break;
     }
     case KVM_SET_REGS: {
         struct kvm_regs *kvm_regs;
 
         kvm_regs = memdup_user(argp, sizeof(*kvm_regs));
         if (IS_ERR(kvm_regs)) {
             r = PTR_ERR(kvm_regs);
             goto out;
         }
         r = kvm_arch_vcpu_ioctl_set_regs(vcpu, kvm_regs);
         kfree(kvm_regs);
         break;
     }
     case KVM_GET_SREGS: {
         kvm_sregs = kzalloc(sizeof(struct kvm_sregs),
                     GFP_KERNEL_ACCOUNT);
         r = -ENOMEM;
         if (!kvm_sregs)
             goto out;
         r = kvm_arch_vcpu_ioctl_get_sregs(vcpu, kvm_sregs);
         if (r)
             goto out;
         r = -EFAULT;
         if (copy_to_user(argp, kvm_sregs, sizeof(struct kvm_sregs)))
             goto out;
         r = 0;
         break;
     }
     case KVM_SET_SREGS: {
         kvm_sregs = memdup_user(argp, sizeof(*kvm_sregs));
         if (IS_ERR(kvm_sregs)) {
             r = PTR_ERR(kvm_sregs);
             kvm_sregs = NULL;
             goto out;
         }
         r = kvm_arch_vcpu_ioctl_set_sregs(vcpu, kvm_sregs);
         break;
     }
     case KVM_GET_MP_STATE: {
         struct kvm_mp_state mp_state;
 
         r = kvm_arch_vcpu_ioctl_get_mpstate(vcpu, &mp_state);
         if (r)
             goto out;
         r = -EFAULT;
         if (copy_to_user(argp, &mp_state, sizeof(mp_state)))
             goto out;
         r = 0;
         break;
     }
     case KVM_SET_MP_STATE: {
         struct kvm_mp_state mp_state;
 
         r = -EFAULT;
         if (copy_from_user(&mp_state, argp, sizeof(mp_state)))
             goto out;
         r = kvm_arch_vcpu_ioctl_set_mpstate(vcpu, &mp_state);
         break;
     }
     case KVM_TRANSLATE: {
         struct kvm_translation tr;
 
         r = -EFAULT;
         if (copy_from_user(&tr, argp, sizeof(tr)))
             goto out;
         r = kvm_arch_vcpu_ioctl_translate(vcpu, &tr);
         if (r)
             goto out;
         r = -EFAULT;
         if (copy_to_user(argp, &tr, sizeof(tr)))
             goto out;
         r = 0;
         break;
     }
     case KVM_SET_GUEST_DEBUG: {
         struct kvm_guest_debug dbg;
 
         r = -EFAULT;
         if (copy_from_user(&dbg, argp, sizeof(dbg)))
             goto out;
         r = kvm_arch_vcpu_ioctl_set_guest_debug(vcpu, &dbg);
         break;
     }
     case KVM_SET_SIGNAL_MASK: {
         struct kvm_signal_mask __user *sigmask_arg = argp;
         struct kvm_signal_mask kvm_sigmask;
         sigset_t sigset, *p;
 
         p = NULL;
         if (argp) {
             r = -EFAULT;
             if (copy_from_user(&kvm_sigmask, argp,
                        sizeof(kvm_sigmask)))
                 goto out;
             r = -EINVAL;
             if (kvm_sigmask.len != sizeof(sigset))
                 goto out;
             r = -EFAULT;
             if (copy_from_user(&sigset, sigmask_arg->sigset,
                        sizeof(sigset)))
                 goto out;
             p = &sigset;
         }
         r = kvm_vcpu_ioctl_set_sigmask(vcpu, p);
         break;
     }
     case KVM_GET_FPU: {
         fpu = kzalloc(sizeof(struct kvm_fpu), GFP_KERNEL_ACCOUNT);
         r = -ENOMEM;
         if (!fpu)
             goto out;
         r = kvm_arch_vcpu_ioctl_get_fpu(vcpu, fpu);
         if (r)
             goto out;
         r = -EFAULT;
         if (copy_to_user(argp, fpu, sizeof(struct kvm_fpu)))
             goto out;
         r = 0;
         break;
     }
     case KVM_SET_FPU: {
         fpu = memdup_user(argp, sizeof(*fpu));
         if (IS_ERR(fpu)) {
             r = PTR_ERR(fpu);
             fpu = NULL;
             goto out;
         }
         r = kvm_arch_vcpu_ioctl_set_fpu(vcpu, fpu);
         break;
     }
     case KVM_GET_STATS_FD: {
         r = kvm_vcpu_ioctl_get_stats_fd(vcpu);
         break;
     }
     default:
         r = kvm_arch_vcpu_ioctl(filp, ioctl, arg);
     }
 out:
     mutex_unlock(&vcpu->mutex);
     kfree(fpu);
     kfree(kvm_sregs);
     return r;
 }
 
 #ifdef CONFIG_KVM_COMPAT
 static long kvm_vcpu_compat_ioctl(struct file *filp,
                   unsigned int ioctl, unsigned long arg)
 {
     struct kvm_vcpu *vcpu = filp->private_data;
     void __user *argp = compat_ptr(arg);
     int r;
 
     if (vcpu->kvm->mm != current->mm || vcpu->kvm->vm_dead)
         return -EIO;
 
     switch (ioctl) {
     case KVM_SET_SIGNAL_MASK: {
         struct kvm_signal_mask __user *sigmask_arg = argp;
         struct kvm_signal_mask kvm_sigmask;
         sigset_t sigset;
 
         if (argp) {
             r = -EFAULT;
             if (copy_from_user(&kvm_sigmask, argp,
                        sizeof(kvm_sigmask)))
                 goto out;
             r = -EINVAL;
             if (kvm_sigmask.len != sizeof(compat_sigset_t))
                 goto out;
             r = -EFAULT;
             if (get_compat_sigset(&sigset,
                           (compat_sigset_t __user *)sigmask_arg->sigset))
                 goto out;
             r = kvm_vcpu_ioctl_set_sigmask(vcpu, &sigset);
         } else
             r = kvm_vcpu_ioctl_set_sigmask(vcpu, NULL);
         break;
     }
     default:
         r = kvm_vcpu_ioctl(filp, ioctl, arg);
     }
 
 out:
     return r;
 }
 #endif
 
 static int kvm_device_mmap(struct file *filp, struct vm_area_struct *vma)
 {
     struct kvm_device *dev = filp->private_data;
 
     if (dev->ops->mmap)
         return dev->ops->mmap(dev, vma);
 
     return -ENODEV;
 }
 
 static int kvm_device_ioctl_attr(struct kvm_device *dev,
                  int (*accessor)(struct kvm_device *dev,
                          struct kvm_device_attr *attr),
                  unsigned long arg)
 {
     struct kvm_device_attr attr;
 
     if (!accessor)
         return -EPERM;
 
     if (copy_from_user(&attr, (void __user *)arg, sizeof(attr)))
         return -EFAULT;
 
     return accessor(dev, &attr);
 }
 
 static long kvm_device_ioctl(struct file *filp, unsigned int ioctl,
                  unsigned long arg)
 {
     struct kvm_device *dev = filp->private_data;
 
     if (dev->kvm->mm != current->mm || dev->kvm->vm_dead)
         return -EIO;
 
     switch (ioctl) {
     case KVM_SET_DEVICE_ATTR:
         return kvm_device_ioctl_attr(dev, dev->ops->set_attr, arg);
     case KVM_GET_DEVICE_ATTR:
         return kvm_device_ioctl_attr(dev, dev->ops->get_attr, arg);
     case KVM_HAS_DEVICE_ATTR:
         return kvm_device_ioctl_attr(dev, dev->ops->has_attr, arg);
     default:
         if (dev->ops->ioctl)
             return dev->ops->ioctl(dev, ioctl, arg);
 
         return -ENOTTY;
     }
 }
 
 static int kvm_device_release(struct inode *inode, struct file *filp)
 {
     struct kvm_device *dev = filp->private_data;
     struct kvm *kvm = dev->kvm;
 
     if (dev->ops->release) {
         mutex_lock(&kvm->lock);
         list_del(&dev->vm_node);
         dev->ops->release(dev);
         mutex_unlock(&kvm->lock);
     }
 
     kvm_put_kvm(kvm);
     return 0;
 }
 
 static const struct file_operations kvm_device_fops = {
     .unlocked_ioctl = kvm_device_ioctl,
     .release = kvm_device_release,
     KVM_COMPAT(kvm_device_ioctl),
     .mmap = kvm_device_mmap,
 };
 
 struct kvm_device *kvm_device_from_filp(struct file *filp)
 {
     if (filp->f_op != &kvm_device_fops)
         return NULL;
 
     return filp->private_data;
 }
 
 static const struct kvm_device_ops *kvm_device_ops_table[KVM_DEV_TYPE_MAX] = {
 #ifdef CONFIG_KVM_MPIC
     [KVM_DEV_TYPE_FSL_MPIC_20]  = &kvm_mpic_ops,
     [KVM_DEV_TYPE_FSL_MPIC_42]  = &kvm_mpic_ops,
 #endif
 };
 
 int kvm_register_device_ops(const struct kvm_device_ops *ops, u32 type)
 {
     if (type >= ARRAY_SIZE(kvm_device_ops_table))
         return -ENOSPC;
 
     if (kvm_device_ops_table[type] != NULL)
         return -EEXIST;
 
     kvm_device_ops_table[type] = ops;
     return 0;
 }
 
 void kvm_unregister_device_ops(u32 type)
 {
     if (kvm_device_ops_table[type] != NULL)
         kvm_device_ops_table[type] = NULL;
 }
 
 static int kvm_ioctl_create_device(struct kvm *kvm,
                    struct kvm_create_device *cd)
 {
     const struct kvm_device_ops *ops;
     struct kvm_device *dev;
     bool test = cd->flags & KVM_CREATE_DEVICE_TEST;
     int type;
     int ret;
 
     if (cd->type >= ARRAY_SIZE(kvm_device_ops_table))
         return -ENODEV;
 
     type = array_index_nospec(cd->type, ARRAY_SIZE(kvm_device_ops_table));
     ops = kvm_device_ops_table[type];
     if (ops == NULL)
         return -ENODEV;
 
     if (test)
         return 0;
 
     dev = kzalloc(sizeof(*dev), GFP_KERNEL_ACCOUNT);
     if (!dev)
         return -ENOMEM;
 
     dev->ops = ops;
     dev->kvm = kvm;
 
     mutex_lock(&kvm->lock);
     ret = ops->create(dev, type);
     if (ret < 0) {
         mutex_unlock(&kvm->lock);
         kfree(dev);
         return ret;
     }
     list_add(&dev->vm_node, &kvm->devices);
     mutex_unlock(&kvm->lock);
 
     if (ops->init)
         ops->init(dev);
 
     kvm_get_kvm(kvm);
     ret = anon_inode_getfd(ops->name, &kvm_device_fops, dev, O_RDWR | O_CLOEXEC);
     if (ret < 0) {
         kvm_put_kvm_no_destroy(kvm);
         mutex_lock(&kvm->lock);
         list_del(&dev->vm_node);
         if (ops->release)
             ops->release(dev);
         mutex_unlock(&kvm->lock);
         if (ops->destroy)
             ops->destroy(dev);
         return ret;
     }
 
     cd->fd = ret;
     return 0;
 }
 
 static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
 {
     switch (arg) {
     case KVM_CAP_USER_MEMORY:
     case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
     case KVM_CAP_JOIN_MEMORY_REGIONS_WORKS:
     case KVM_CAP_INTERNAL_ERROR_DATA:
 #ifdef CONFIG_HAVE_KVM_MSI
     case KVM_CAP_SIGNAL_MSI:
 #endif
 #ifdef CONFIG_HAVE_KVM_IRQFD
     case KVM_CAP_IRQFD:
     case KVM_CAP_IRQFD_RESAMPLE:
 #endif
     case KVM_CAP_IOEVENTFD_ANY_LENGTH:
     case KVM_CAP_CHECK_EXTENSION_VM:
     case KVM_CAP_ENABLE_CAP_VM:
     case KVM_CAP_HALT_POLL:
         return 1;
 #ifdef CONFIG_KVM_MMIO
     case KVM_CAP_COALESCED_MMIO:
         return KVM_COALESCED_MMIO_PAGE_OFFSET;
     case KVM_CAP_COALESCED_PIO:
         return 1;
 #endif
 #ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
     case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2:
         return KVM_DIRTY_LOG_MANUAL_CAPS;
 #endif
 #ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
     case KVM_CAP_IRQ_ROUTING:
         return KVM_MAX_IRQ_ROUTES;
 #endif
 #if KVM_ADDRESS_SPACE_NUM > 1
     case KVM_CAP_MULTI_ADDRESS_SPACE:
         return KVM_ADDRESS_SPACE_NUM;
 #endif
     case KVM_CAP_NR_MEMSLOTS:
         return KVM_USER_MEM_SLOTS;
     case KVM_CAP_DIRTY_LOG_RING:
 #ifdef CONFIG_HAVE_KVM_DIRTY_RING
         return KVM_DIRTY_RING_MAX_ENTRIES * sizeof(struct kvm_dirty_gfn);
 #else
         return 0;
 #endif
     case KVM_CAP_BINARY_STATS_FD:
     case KVM_CAP_SYSTEM_EVENT_DATA:
         return 1;
     default:
         break;
     }
     return kvm_vm_ioctl_check_extension(kvm, arg);
 }
 
 static int kvm_vm_ioctl_enable_dirty_log_ring(struct kvm *kvm, u32 size)
 {
     int r;
 
     if (!KVM_DIRTY_LOG_PAGE_OFFSET)
         return -EINVAL;
 
     /* the size should be power of 2 */
     if (!size || (size & (size - 1)))
         return -EINVAL;
 
     /* Should be bigger to keep the reserved entries, or a page */
     if (size < kvm_dirty_ring_get_rsvd_entries() *
         sizeof(struct kvm_dirty_gfn) || size < PAGE_SIZE)
         return -EINVAL;
 
     if (size > KVM_DIRTY_RING_MAX_ENTRIES *
         sizeof(struct kvm_dirty_gfn))
         return -E2BIG;
 
     /* We only allow it to set once */
     if (kvm->dirty_ring_size)
         return -EINVAL;
 
     mutex_lock(&kvm->lock);
 
     if (kvm->created_vcpus) {
         /* We don't allow to change this value after vcpu created */
         r = -EINVAL;
     } else {
         kvm->dirty_ring_size = size;
         r = 0;
     }
 
     mutex_unlock(&kvm->lock);
     return r;
 }
 
 static int kvm_vm_ioctl_reset_dirty_pages(struct kvm *kvm)
 {
     unsigned long i;
     struct kvm_vcpu *vcpu;
     int cleared = 0;
 
     if (!kvm->dirty_ring_size)
         return -EINVAL;
 
     mutex_lock(&kvm->slots_lock);
 
     kvm_for_each_vcpu(i, vcpu, kvm)
         cleared += kvm_dirty_ring_reset(vcpu->kvm, &vcpu->dirty_ring);
 
     mutex_unlock(&kvm->slots_lock);
 
     if (cleared)
         kvm_flush_remote_tlbs(kvm);
 
     return cleared;
 }
 
 int __attribute__((weak)) kvm_vm_ioctl_enable_cap(struct kvm *kvm,
                           struct kvm_enable_cap *cap)
 {
     return -EINVAL;
 }
 
 static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm,
                        struct kvm_enable_cap *cap)
 {
     switch (cap->cap) {
 #ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
     case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2: {
         u64 allowed_options = KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE;
 
         if (cap->args[0] & KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE)
             allowed_options = KVM_DIRTY_LOG_MANUAL_CAPS;
 
         if (cap->flags || (cap->args[0] & ~allowed_options))
             return -EINVAL;
         kvm->manual_dirty_log_protect = cap->args[0];
         return 0;
     }
 #endif
     case KVM_CAP_HALT_POLL: {
         if (cap->flags || cap->args[0] != (unsigned int)cap->args[0])
             return -EINVAL;
 
         kvm->max_halt_poll_ns = cap->args[0];
         return 0;
     }
     case KVM_CAP_DIRTY_LOG_RING:
         return kvm_vm_ioctl_enable_dirty_log_ring(kvm, cap->args[0]);
     default:
         return kvm_vm_ioctl_enable_cap(kvm, cap);
     }
 }
 
 static ssize_t kvm_vm_stats_read(struct file *file, char __user *user_buffer,
                   size_t size, loff_t *offset)
 {
     struct kvm *kvm = file->private_data;
 
     return kvm_stats_read(kvm->stats_id, &kvm_vm_stats_header,
                 &kvm_vm_stats_desc[0], &kvm->stat,
                 sizeof(kvm->stat), user_buffer, size, offset);
 }
 
 static const struct file_operations kvm_vm_stats_fops = {
     .read = kvm_vm_stats_read,
     .llseek = noop_llseek,
 };
 
 static int kvm_vm_ioctl_get_stats_fd(struct kvm *kvm)
 {
     int fd;
     struct file *file;
 
     fd = get_unused_fd_flags(O_CLOEXEC);
     if (fd < 0)
         return fd;
 
     file = anon_inode_getfile("kvm-vm-stats",
             &kvm_vm_stats_fops, kvm, O_RDONLY);
     if (IS_ERR(file)) {
         put_unused_fd(fd);
         return PTR_ERR(file);
     }
     file->f_mode |= FMODE_PREAD;
     fd_install(fd, file);
 
     return fd;
 }
 
 static long kvm_vm_ioctl(struct file *filp,
                unsigned int ioctl, unsigned long arg)
 {
     struct kvm *kvm = filp->private_data;
     void __user *argp = (void __user *)arg;
     int r;
 
     if (kvm->mm != current->mm || kvm->vm_dead)
         return -EIO;
     switch (ioctl) {
     case KVM_CREATE_VCPU:
         r = kvm_vm_ioctl_create_vcpu(kvm, arg);
         break;
     case KVM_ENABLE_CAP: {
         struct kvm_enable_cap cap;
 
         r = -EFAULT;
         if (copy_from_user(&cap, argp, sizeof(cap)))
             goto out;
         r = kvm_vm_ioctl_enable_cap_generic(kvm, &cap);
         break;
     }
     case KVM_SET_USER_MEMORY_REGION: {
         struct kvm_userspace_memory_region kvm_userspace_mem;
 
         r = -EFAULT;
         if (copy_from_user(&kvm_userspace_mem, argp,
                         sizeof(kvm_userspace_mem)))
             goto out;
 
         r = kvm_vm_ioctl_set_memory_region(kvm, &kvm_userspace_mem);
         break;
     }
     case KVM_GET_DIRTY_LOG: {
         struct kvm_dirty_log log;
 
         r = -EFAULT;
         if (copy_from_user(&log, argp, sizeof(log)))
             goto out;
         r = kvm_vm_ioctl_get_dirty_log(kvm, &log);
         break;
     }
 #ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
     case KVM_CLEAR_DIRTY_LOG: {
         struct kvm_clear_dirty_log log;
 
         r = -EFAULT;
         if (copy_from_user(&log, argp, sizeof(log)))
             goto out;
         r = kvm_vm_ioctl_clear_dirty_log(kvm, &log);
         break;
     }
 #endif
 #ifdef CONFIG_KVM_MMIO
     case KVM_REGISTER_COALESCED_MMIO: {
         struct kvm_coalesced_mmio_zone zone;
 
         r = -EFAULT;
         if (copy_from_user(&zone, argp, sizeof(zone)))
             goto out;
         r = kvm_vm_ioctl_register_coalesced_mmio(kvm, &zone);
         break;
     }
     case KVM_UNREGISTER_COALESCED_MMIO: {
         struct kvm_coalesced_mmio_zone zone;
 
         r = -EFAULT;
         if (copy_from_user(&zone, argp, sizeof(zone)))
             goto out;
         r = kvm_vm_ioctl_unregister_coalesced_mmio(kvm, &zone);
         break;
     }
 #endif
     case KVM_IRQFD: {
         struct kvm_irqfd data;
 
         r = -EFAULT;
         if (copy_from_user(&data, argp, sizeof(data)))
             goto out;
         r = kvm_irqfd(kvm, &data);
         break;
     }
     case KVM_IOEVENTFD: {
         struct kvm_ioeventfd data;
 
         r = -EFAULT;
         if (copy_from_user(&data, argp, sizeof(data)))
             goto out;
         r = kvm_ioeventfd(kvm, &data);
         break;
     }
 #ifdef CONFIG_HAVE_KVM_MSI
     case KVM_SIGNAL_MSI: {
         struct kvm_msi msi;
 
         r = -EFAULT;
         if (copy_from_user(&msi, argp, sizeof(msi)))
             goto out;
         r = kvm_send_userspace_msi(kvm, &msi);
         break;
     }
 #endif
 #ifdef __KVM_HAVE_IRQ_LINE
     case KVM_IRQ_LINE_STATUS:
     case KVM_IRQ_LINE: {
         struct kvm_irq_level irq_event;
 
         r = -EFAULT;
         if (copy_from_user(&irq_event, argp, sizeof(irq_event)))
             goto out;
 
         r = kvm_vm_ioctl_irq_line(kvm, &irq_event,
                     ioctl == KVM_IRQ_LINE_STATUS);
         if (r)
             goto out;
 
         r = -EFAULT;
         if (ioctl == KVM_IRQ_LINE_STATUS) {
             if (copy_to_user(argp, &irq_event, sizeof(irq_event)))
                 goto out;
         }
 
         r = 0;
         break;
     }
 #endif
 #ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
     case KVM_SET_GSI_ROUTING: {
         struct kvm_irq_routing routing;
         struct kvm_irq_routing __user *urouting;
         struct kvm_irq_routing_entry *entries = NULL;
 
         r = -EFAULT;
         if (copy_from_user(&routing, argp, sizeof(routing)))
             goto out;
         r = -EINVAL;
         if (!kvm_arch_can_set_irq_routing(kvm))
             goto out;
         if (routing.nr > KVM_MAX_IRQ_ROUTES)
             goto out;
         if (routing.flags)
             goto out;
         if (routing.nr) {
             urouting = argp;
             entries = vmemdup_user(urouting->entries,
                            array_size(sizeof(*entries),
                               routing.nr));
             if (IS_ERR(entries)) {
                 r = PTR_ERR(entries);
                 goto out;
             }
         }
         r = kvm_set_irq_routing(kvm, entries, routing.nr,
                     routing.flags);
         kvfree(entries);
         break;
     }
 #endif /* CONFIG_HAVE_KVM_IRQ_ROUTING */
     case KVM_CREATE_DEVICE: {
         struct kvm_create_device cd;
 
         r = -EFAULT;
         if (copy_from_user(&cd, argp, sizeof(cd)))
             goto out;
 
         r = kvm_ioctl_create_device(kvm, &cd);
         if (r)
             goto out;
 
         r = -EFAULT;
         if (copy_to_user(argp, &cd, sizeof(cd)))
             goto out;
 
         r = 0;
         break;
     }
     case KVM_CHECK_EXTENSION:
         r = kvm_vm_ioctl_check_extension_generic(kvm, arg);
         break;
     case KVM_RESET_DIRTY_RINGS:
         r = kvm_vm_ioctl_reset_dirty_pages(kvm);
         break;
     case KVM_GET_STATS_FD:
         r = kvm_vm_ioctl_get_stats_fd(kvm);
         break;
     default:
         r = kvm_arch_vm_ioctl(filp, ioctl, arg);
     }
 out:
     return r;
 }
 
 #ifdef CONFIG_KVM_COMPAT
 struct compat_kvm_dirty_log {
     __u32 slot;
     __u32 padding1;
     union {
         compat_uptr_t dirty_bitmap; /* one bit per page */
         __u64 padding2;
     };
 };
 
 struct compat_kvm_clear_dirty_log {
     __u32 slot;
     __u32 num_pages;
     __u64 first_page;
     union {
         compat_uptr_t dirty_bitmap; /* one bit per page */
         __u64 padding2;
     };
 };
 
 static long kvm_vm_compat_ioctl(struct file *filp,
                unsigned int ioctl, unsigned long arg)
 {
     struct kvm *kvm = filp->private_data;
     int r;
 
     if (kvm->mm != current->mm || kvm->vm_dead)
         return -EIO;
     switch (ioctl) {
 #ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
     case KVM_CLEAR_DIRTY_LOG: {
         struct compat_kvm_clear_dirty_log compat_log;
         struct kvm_clear_dirty_log log;
 
         if (copy_from_user(&compat_log, (void __user *)arg,
                    sizeof(compat_log)))
             return -EFAULT;
         log.slot     = compat_log.slot;
         log.num_pages    = compat_log.num_pages;
         log.first_page   = compat_log.first_page;
         log.padding2     = compat_log.padding2;
         log.dirty_bitmap = compat_ptr(compat_log.dirty_bitmap);
 
         r = kvm_vm_ioctl_clear_dirty_log(kvm, &log);
         break;
     }
 #endif
     case KVM_GET_DIRTY_LOG: {
         struct compat_kvm_dirty_log compat_log;
         struct kvm_dirty_log log;
 
         if (copy_from_user(&compat_log, (void __user *)arg,
                    sizeof(compat_log)))
             return -EFAULT;
         log.slot     = compat_log.slot;
         log.padding1     = compat_log.padding1;
         log.padding2     = compat_log.padding2;
         log.dirty_bitmap = compat_ptr(compat_log.dirty_bitmap);
 
         r = kvm_vm_ioctl_get_dirty_log(kvm, &log);
         break;
     }
     default:
         r = kvm_vm_ioctl(filp, ioctl, arg);
     }
     return r;
 }
 #endif
 
 static const struct file_operations kvm_vm_fops = {
     .release        = kvm_vm_release,
     .unlocked_ioctl = kvm_vm_ioctl,
     .llseek     = noop_llseek,
     KVM_COMPAT(kvm_vm_compat_ioctl),
 };
 
 bool file_is_kvm(struct file *file)
 {
     return file && file->f_op == &kvm_vm_fops;
 }
 EXPORT_SYMBOL_GPL(file_is_kvm);
 
 static int kvm_dev_ioctl_create_vm(unsigned long type)
 {
     char fdname[ITOA_MAX_LEN + 1];
     int r, fd;
     struct kvm *kvm;
     struct file *file;
 
     fd = get_unused_fd_flags(O_CLOEXEC);
     if (fd < 0)
         return fd;
 
     snprintf(fdname, sizeof(fdname), "%d", fd);
 
     kvm = kvm_create_vm(type, fdname);
     if (IS_ERR(kvm)) {
         r = PTR_ERR(kvm);
         goto put_fd;
     }
 
     file = anon_inode_getfile("kvm-vm", &kvm_vm_fops, kvm, O_RDWR);
     if (IS_ERR(file)) {
         r = PTR_ERR(file);
         goto put_kvm;
     }
 
     /*
      * Don't call kvm_put_kvm anymore at this point; file->f_op is
      * already set, with ->release() being kvm_vm_release().  In error
      * cases it will be called by the final fput(file) and will take
      * care of doing kvm_put_kvm(kvm).
      */
     kvm_uevent_notify_change(KVM_EVENT_CREATE_VM, kvm);
 
     fd_install(fd, file);
     return fd;
 
 put_kvm:
     kvm_put_kvm(kvm);
 put_fd:
     put_unused_fd(fd);
     return r;
 }
 
 static long kvm_dev_ioctl(struct file *filp,
               unsigned int ioctl, unsigned long arg)
 {
     long r = -EINVAL;
 
     switch (ioctl) {
     case KVM_GET_API_VERSION:
         if (arg)
             goto out;
         r = KVM_API_VERSION;
         break;
     case KVM_CREATE_VM:
         r = kvm_dev_ioctl_create_vm(arg);
         break;
     case KVM_CHECK_EXTENSION:
         r = kvm_vm_ioctl_check_extension_generic(NULL, arg);
         break;
     case KVM_GET_VCPU_MMAP_SIZE:
         if (arg)
             goto out;
         r = PAGE_SIZE;     /* struct kvm_run */
 #ifdef CONFIG_X86
         r += PAGE_SIZE;    /* pio data page */
 #endif
 #ifdef CONFIG_KVM_MMIO
         r += PAGE_SIZE;    /* coalesced mmio ring page */
 #endif
         break;
     case KVM_TRACE_ENABLE:
     case KVM_TRACE_PAUSE:
     case KVM_TRACE_DISABLE:
         r = -EOPNOTSUPP;
         break;
     default:
         return kvm_arch_dev_ioctl(filp, ioctl, arg);
     }
 out:
     return r;
 }
 
 static struct file_operations kvm_chardev_ops = {
     .unlocked_ioctl = kvm_dev_ioctl,
     .llseek     = noop_llseek,
     KVM_COMPAT(kvm_dev_ioctl),
 };
 
 static struct miscdevice kvm_dev = {
     KVM_MINOR,
     "kvm",
     &kvm_chardev_ops,
 };
 
 static void hardware_enable_nolock(void *junk)
 {
     int cpu = raw_smp_processor_id();
     int r;
 
     if (cpumask_test_cpu(cpu, cpus_hardware_enabled))
         return;
 
     cpumask_set_cpu(cpu, cpus_hardware_enabled);
 
     r = kvm_arch_hardware_enable();
 
     if (r) {
         cpumask_clear_cpu(cpu, cpus_hardware_enabled);
         atomic_inc(&hardware_enable_failed);
         pr_info("kvm: enabling virtualization on CPU%d failed\n", cpu);
     }
 }
 
 static int kvm_starting_cpu(unsigned int cpu)
 {
     raw_spin_lock(&kvm_count_lock);
     if (kvm_usage_count)
         hardware_enable_nolock(NULL);
     raw_spin_unlock(&kvm_count_lock);
     return 0;
 }
 
 static void hardware_disable_nolock(void *junk)
 {
     int cpu = raw_smp_processor_id();
 
     if (!cpumask_test_cpu(cpu, cpus_hardware_enabled))
         return;
     cpumask_clear_cpu(cpu, cpus_hardware_enabled);
     kvm_arch_hardware_disable();
 }
 
 static int kvm_dying_cpu(unsigned int cpu)
 {
     raw_spin_lock(&kvm_count_lock);
     if (kvm_usage_count)
         hardware_disable_nolock(NULL);
     raw_spin_unlock(&kvm_count_lock);
     return 0;
 }
 
 static void hardware_disable_all_nolock(void)
 {
     BUG_ON(!kvm_usage_count);
 
     kvm_usage_count--;
     if (!kvm_usage_count)
         on_each_cpu(hardware_disable_nolock, NULL, 1);
 }
 
 static void hardware_disable_all(void)
 {
     raw_spin_lock(&kvm_count_lock);
     hardware_disable_all_nolock();
     raw_spin_unlock(&kvm_count_lock);
 }
 
 static int hardware_enable_all(void)
 {
     int r = 0;
 
     raw_spin_lock(&kvm_count_lock);
 
     kvm_usage_count++;
     if (kvm_usage_count == 1) {
         atomic_set(&hardware_enable_failed, 0);
         on_each_cpu(hardware_enable_nolock, NULL, 1);
 
         if (atomic_read(&hardware_enable_failed)) {
             hardware_disable_all_nolock();
             r = -EBUSY;
         }
     }
 
     raw_spin_unlock(&kvm_count_lock);
 
     return r;
 }
 
 static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
               void *v)
 {
     /*
      * Some (well, at least mine) BIOSes hang on reboot if
      * in vmx root mode.
      *
      * And Intel TXT required VMX off for all cpu when system shutdown.
      */
     pr_info("kvm: exiting hardware virtualization\n");
     kvm_rebooting = true;
     on_each_cpu(hardware_disable_nolock, NULL, 1);
     return NOTIFY_OK;
 }
 
 static struct notifier_block kvm_reboot_notifier = {
     .notifier_call = kvm_reboot,
     .priority = 0,
 };
 
 static void kvm_io_bus_destroy(struct kvm_io_bus *bus)
 {
     int i;
 
     for (i = 0; i < bus->dev_count; i++) {
         struct kvm_io_device *pos = bus->range[i].dev;
 
         kvm_iodevice_destructor(pos);
     }
     kfree(bus);
 }
 
 static inline int kvm_io_bus_cmp(const struct kvm_io_range *r1,
                  const struct kvm_io_range *r2)
 {
     gpa_t addr1 = r1->addr;
     gpa_t addr2 = r2->addr;
 
     if (addr1 < addr2)
         return -1;
 
     /* If r2->len == 0, match the exact address.  If r2->len != 0,
      * accept any overlapping write.  Any order is acceptable for
      * overlapping ranges, because kvm_io_bus_get_first_dev ensures
      * we process all of them.
      */
     if (r2->len) {
         addr1 += r1->len;
         addr2 += r2->len;
     }
 
     if (addr1 > addr2)
         return 1;
 
     return 0;
 }
 
 static int kvm_io_bus_sort_cmp(const void *p1, const void *p2)
 {
     return kvm_io_bus_cmp(p1, p2);
 }
 
 static int kvm_io_bus_get_first_dev(struct kvm_io_bus *bus,
                  gpa_t addr, int len)
 {
     struct kvm_io_range *range, key;
     int off;
 
     key = (struct kvm_io_range) {
         .addr = addr,
         .len = len,
     };
 
     range = bsearch(&key, bus->range, bus->dev_count,
             sizeof(struct kvm_io_range), kvm_io_bus_sort_cmp);
     if (range == NULL)
         return -ENOENT;
 
     off = range - bus->range;
 
     while (off > 0 && kvm_io_bus_cmp(&key, &bus->range[off-1]) == 0)
         off--;
 
     return off;
 }
 
 static int __kvm_io_bus_write(struct kvm_vcpu *vcpu, struct kvm_io_bus *bus,
                   struct kvm_io_range *range, const void *val)
 {
     int idx;
 
     idx = kvm_io_bus_get_first_dev(bus, range->addr, range->len);
     if (idx < 0)
         return -EOPNOTSUPP;
 
     while (idx < bus->dev_count &&
         kvm_io_bus_cmp(range, &bus->range[idx]) == 0) {
         if (!kvm_iodevice_write(vcpu, bus->range[idx].dev, range->addr,
                     range->len, val))
             return idx;
         idx++;
     }
 
     return -EOPNOTSUPP;
 }
 
 /* kvm_io_bus_write - called under kvm->slots_lock */
 int kvm_io_bus_write(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr,
              int len, const void *val)
 {
     struct kvm_io_bus *bus;
     struct kvm_io_range range;
     int r;
 
     range = (struct kvm_io_range) {
         .addr = addr,
         .len = len,
     };
 
     bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu);
     if (!bus)
         return -ENOMEM;
     r = __kvm_io_bus_write(vcpu, bus, &range, val);
     return r < 0 ? r : 0;
 }
 EXPORT_SYMBOL_GPL(kvm_io_bus_write);
 
 /* kvm_io_bus_write_cookie - called under kvm->slots_lock */
 int kvm_io_bus_write_cookie(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx,
                 gpa_t addr, int len, const void *val, long cookie)
 {
     struct kvm_io_bus *bus;
     struct kvm_io_range range;
 
     range = (struct kvm_io_range) {
         .addr = addr,
         .len = len,
     };
 
     bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu);
     if (!bus)
         return -ENOMEM;
 
     /* First try the device referenced by cookie. */
     if ((cookie >= 0) && (cookie < bus->dev_count) &&
         (kvm_io_bus_cmp(&range, &bus->range[cookie]) == 0))
         if (!kvm_iodevice_write(vcpu, bus->range[cookie].dev, addr, len,
                     val))
             return cookie;
 
     /*
      * cookie contained garbage; fall back to search and return the
      * correct cookie value.
      */
     return __kvm_io_bus_write(vcpu, bus, &range, val);
 }
 
 static int __kvm_io_bus_read(struct kvm_vcpu *vcpu, struct kvm_io_bus *bus,
                  struct kvm_io_range *range, void *val)
 {
     int idx;
 
     idx = kvm_io_bus_get_first_dev(bus, range->addr, range->len);
     if (idx < 0)
         return -EOPNOTSUPP;
 
     while (idx < bus->dev_count &&
         kvm_io_bus_cmp(range, &bus->range[idx]) == 0) {
         if (!kvm_iodevice_read(vcpu, bus->range[idx].dev, range->addr,
                        range->len, val))
             return idx;
         idx++;
     }
 
     return -EOPNOTSUPP;
 }
 
 /* kvm_io_bus_read - called under kvm->slots_lock */
 int kvm_io_bus_read(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr,
             int len, void *val)
 {
     struct kvm_io_bus *bus;
     struct kvm_io_range range;
     int r;
 
     range = (struct kvm_io_range) {
         .addr = addr,
         .len = len,
     };
 
     bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu);
     if (!bus)
         return -ENOMEM;
     r = __kvm_io_bus_read(vcpu, bus, &range, val);
     return r < 0 ? r : 0;
 }
 
 /* Caller must hold slots_lock. */
 int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
                 int len, struct kvm_io_device *dev)
 {
     int i;
     struct kvm_io_bus *new_bus, *bus;
     struct kvm_io_range range;
 
     bus = kvm_get_bus(kvm, bus_idx);
     if (!bus)
         return -ENOMEM;
 
     /* exclude ioeventfd which is limited by maximum fd */
     if (bus->dev_count - bus->ioeventfd_count > NR_IOBUS_DEVS - 1)
         return -ENOSPC;
 
     new_bus = kmalloc(struct_size(bus, range, bus->dev_count + 1),
               GFP_KERNEL_ACCOUNT);
     if (!new_bus)
         return -ENOMEM;
 
     range = (struct kvm_io_range) {
         .addr = addr,
         .len = len,
         .dev = dev,
     };
 
     for (i = 0; i < bus->dev_count; i++)
         if (kvm_io_bus_cmp(&bus->range[i], &range) > 0)
             break;
 
     memcpy(new_bus, bus, sizeof(*bus) + i * sizeof(struct kvm_io_range));
     new_bus->dev_count++;
     new_bus->range[i] = range;
     memcpy(new_bus->range + i + 1, bus->range + i,
         (bus->dev_count - i) * sizeof(struct kvm_io_range));
     rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
     synchronize_srcu_expedited(&kvm->srcu);
     kfree(bus);
 
     return 0;
 }
 
 int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
                   struct kvm_io_device *dev)
 {
     int i, j;
     struct kvm_io_bus *new_bus, *bus;
 
     lockdep_assert_held(&kvm->slots_lock);
 
     bus = kvm_get_bus(kvm, bus_idx);
     if (!bus)
         return 0;
 
     for (i = 0; i < bus->dev_count; i++) {
         if (bus->range[i].dev == dev) {
             break;
         }
     }
 
     if (i == bus->dev_count)
         return 0;
 
     new_bus = kmalloc(struct_size(bus, range, bus->dev_count - 1),
               GFP_KERNEL_ACCOUNT);
     if (new_bus) {
         memcpy(new_bus, bus, struct_size(bus, range, i));
         new_bus->dev_count--;
         memcpy(new_bus->range + i, bus->range + i + 1,
                 flex_array_size(new_bus, range, new_bus->dev_count - i));
     }
 
     rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
     synchronize_srcu_expedited(&kvm->srcu);
 
     /* Destroy the old bus _after_ installing the (null) bus. */
     if (!new_bus) {
         pr_err("kvm: failed to shrink bus, removing it completely\n");
         for (j = 0; j < bus->dev_count; j++) {
             if (j == i)
                 continue;
             kvm_iodevice_destructor(bus->range[j].dev);
         }
     }
 
     kfree(bus);
     return new_bus ? 0 : -ENOMEM;
 }
 
 struct kvm_io_device *kvm_io_bus_get_dev(struct kvm *kvm, enum kvm_bus bus_idx,
                      gpa_t addr)
 {
     struct kvm_io_bus *bus;
     int dev_idx, srcu_idx;
     struct kvm_io_device *iodev = NULL;
 
     srcu_idx = srcu_read_lock(&kvm->srcu);
 
     bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
     if (!bus)
         goto out_unlock;
 
     dev_idx = kvm_io_bus_get_first_dev(bus, addr, 1);
     if (dev_idx < 0)
         goto out_unlock;
 
     iodev = bus->range[dev_idx].dev;
 
 out_unlock:
     srcu_read_unlock(&kvm->srcu, srcu_idx);
 
     return iodev;
 }
 EXPORT_SYMBOL_GPL(kvm_io_bus_get_dev);
 
 static int kvm_debugfs_open(struct inode *inode, struct file *file,
                int (*get)(void *, u64 *), int (*set)(void *, u64),
                const char *fmt)
 {
     struct kvm_stat_data *stat_data = (struct kvm_stat_data *)
                       inode->i_private;
 
     /*
      * The debugfs files are a reference to the kvm struct which
         * is still valid when kvm_destroy_vm is called.  kvm_get_kvm_safe
         * avoids the race between open and the removal of the debugfs directory.
      */
     if (!kvm_get_kvm_safe(stat_data->kvm))
         return -ENOENT;
 
     if (simple_attr_open(inode, file, get,
             kvm_stats_debugfs_mode(stat_data->desc) & 0222
             ? set : NULL,
             fmt)) {
         kvm_put_kvm(stat_data->kvm);
         return -ENOMEM;
     }
 
     return 0;
 }
 
 static int kvm_debugfs_release(struct inode *inode, struct file *file)
 {
     struct kvm_stat_data *stat_data = (struct kvm_stat_data *)
                       inode->i_private;
 
     simple_attr_release(inode, file);
     kvm_put_kvm(stat_data->kvm);
 
     return 0;
 }
 
 static int kvm_get_stat_per_vm(struct kvm *kvm, size_t offset, u64 *val)
 {
     *val = *(u64 *)((void *)(&kvm->stat) + offset);
 
     return 0;
 }
 
 static int kvm_clear_stat_per_vm(struct kvm *kvm, size_t offset)
 {
     *(u64 *)((void *)(&kvm->stat) + offset) = 0;
 
     return 0;
 }
 
 static int kvm_get_stat_per_vcpu(struct kvm *kvm, size_t offset, u64 *val)
 {
     unsigned long i;
     struct kvm_vcpu *vcpu;
 
     *val = 0;
 
     kvm_for_each_vcpu(i, vcpu, kvm)
         *val += *(u64 *)((void *)(&vcpu->stat) + offset);
 
     return 0;
 }
 
 static int kvm_clear_stat_per_vcpu(struct kvm *kvm, size_t offset)
 {
     unsigned long i;
     struct kvm_vcpu *vcpu;
 
     kvm_for_each_vcpu(i, vcpu, kvm)
         *(u64 *)((void *)(&vcpu->stat) + offset) = 0;
 
     return 0;
 }
 
 static int kvm_stat_data_get(void *data, u64 *val)
 {
     int r = -EFAULT;
     struct kvm_stat_data *stat_data = (struct kvm_stat_data *)data;
 
     switch (stat_data->kind) {
     case KVM_STAT_VM:
         r = kvm_get_stat_per_vm(stat_data->kvm,
                     stat_data->desc->desc.offset, val);
         break;
     case KVM_STAT_VCPU:
         r = kvm_get_stat_per_vcpu(stat_data->kvm,
                       stat_data->desc->desc.offset, val);
         break;
     }
 
     return r;
 }
 
 static int kvm_stat_data_clear(void *data, u64 val)
 {
     int r = -EFAULT;
     struct kvm_stat_data *stat_data = (struct kvm_stat_data *)data;
 
     if (val)
         return -EINVAL;
 
     switch (stat_data->kind) {
     case KVM_STAT_VM:
         r = kvm_clear_stat_per_vm(stat_data->kvm,
                       stat_data->desc->desc.offset);
         break;
     case KVM_STAT_VCPU:
         r = kvm_clear_stat_per_vcpu(stat_data->kvm,
                         stat_data->desc->desc.offset);
         break;
     }
 
     return r;
 }
 
 static int kvm_stat_data_open(struct inode *inode, struct file *file)
 {
     __simple_attr_check_format("%llu\n", 0ull);
     return kvm_debugfs_open(inode, file, kvm_stat_data_get,
                 kvm_stat_data_clear, "%llu\n");
 }
 
 static const struct file_operations stat_fops_per_vm = {
     .owner = THIS_MODULE,
     .open = kvm_stat_data_open,
     .release = kvm_debugfs_release,
     .read = simple_attr_read,
     .write = simple_attr_write,
     .llseek = no_llseek,
 };
 
 static int vm_stat_get(void *_offset, u64 *val)
 {
     unsigned offset = (long)_offset;
     struct kvm *kvm;
     u64 tmp_val;
 
     *val = 0;
     mutex_lock(&kvm_lock);
     list_for_each_entry(kvm, &vm_list, vm_list) {
         kvm_get_stat_per_vm(kvm, offset, &tmp_val);
         *val += tmp_val;
     }
     mutex_unlock(&kvm_lock);
     return 0;
 }
 
 static int vm_stat_clear(void *_offset, u64 val)
 {
     unsigned offset = (long)_offset;
     struct kvm *kvm;
 
     if (val)
         return -EINVAL;
 
     mutex_lock(&kvm_lock);
     list_for_each_entry(kvm, &vm_list, vm_list) {
         kvm_clear_stat_per_vm(kvm, offset);
     }
     mutex_unlock(&kvm_lock);
 
     return 0;
 }
 
 DEFINE_SIMPLE_ATTRIBUTE(vm_stat_fops, vm_stat_get, vm_stat_clear, "%llu\n");
 DEFINE_SIMPLE_ATTRIBUTE(vm_stat_readonly_fops, vm_stat_get, NULL, "%llu\n");
 
 static int vcpu_stat_get(void *_offset, u64 *val)
 {
     unsigned offset = (long)_offset;
     struct kvm *kvm;
     u64 tmp_val;
 
     *val = 0;
     mutex_lock(&kvm_lock);
     list_for_each_entry(kvm, &vm_list, vm_list) {
         kvm_get_stat_per_vcpu(kvm, offset, &tmp_val);
         *val += tmp_val;
     }
     mutex_unlock(&kvm_lock);
     return 0;
 }
 
 static int vcpu_stat_clear(void *_offset, u64 val)
 {
     unsigned offset = (long)_offset;
     struct kvm *kvm;
 
     if (val)
         return -EINVAL;
 
     mutex_lock(&kvm_lock);
     list_for_each_entry(kvm, &vm_list, vm_list) {
         kvm_clear_stat_per_vcpu(kvm, offset);
     }
     mutex_unlock(&kvm_lock);
 
     return 0;
 }
 
 DEFINE_SIMPLE_ATTRIBUTE(vcpu_stat_fops, vcpu_stat_get, vcpu_stat_clear,
             "%llu\n");
 DEFINE_SIMPLE_ATTRIBUTE(vcpu_stat_readonly_fops, vcpu_stat_get, NULL, "%llu\n");
 
 static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
 {
     struct kobj_uevent_env *env;
     unsigned long long created, active;
 
     if (!kvm_dev.this_device || !kvm)
         return;
 
     mutex_lock(&kvm_lock);
     if (type == KVM_EVENT_CREATE_VM) {
         kvm_createvm_count++;
         kvm_active_vms++;
     } else if (type == KVM_EVENT_DESTROY_VM) {
         kvm_active_vms--;
     }
     created = kvm_createvm_count;
     active = kvm_active_vms;
     mutex_unlock(&kvm_lock);
 
     env = kzalloc(sizeof(*env), GFP_KERNEL_ACCOUNT);
     if (!env)
         return;
 
     add_uevent_var(env, "CREATED=%llu", created);
     add_uevent_var(env, "COUNT=%llu", active);
 
     if (type == KVM_EVENT_CREATE_VM) {
         add_uevent_var(env, "EVENT=create");
         kvm->userspace_pid = task_pid_nr(current);
     } else if (type == KVM_EVENT_DESTROY_VM) {
         add_uevent_var(env, "EVENT=destroy");
     }
     add_uevent_var(env, "PID=%d", kvm->userspace_pid);
 
     if (!IS_ERR(kvm->debugfs_dentry)) {
         char *tmp, *p = kmalloc(PATH_MAX, GFP_KERNEL_ACCOUNT);
 
         if (p) {
             tmp = dentry_path_raw(kvm->debugfs_dentry, p, PATH_MAX);
             if (!IS_ERR(tmp))
                 add_uevent_var(env, "STATS_PATH=%s", tmp);
             kfree(p);
         }
     }
     /* no need for checks, since we are adding at most only 5 keys */
     env->envp[env->envp_idx++] = NULL;
     kobject_uevent_env(&kvm_dev.this_device->kobj, KOBJ_CHANGE, env->envp);
     kfree(env);
 }
 
 static void kvm_init_debug(void)
 {
     const struct file_operations *fops;
     const struct _kvm_stats_desc *pdesc;
     int i;
 
     kvm_debugfs_dir = debugfs_create_dir("kvm", NULL);
 
     for (i = 0; i < kvm_vm_stats_header.num_desc; ++i) {
         pdesc = &kvm_vm_stats_desc[i];
         if (kvm_stats_debugfs_mode(pdesc) & 0222)
             fops = &vm_stat_fops;
         else
             fops = &vm_stat_readonly_fops;
         debugfs_create_file(pdesc->name, kvm_stats_debugfs_mode(pdesc),
                 kvm_debugfs_dir,
                 (void *)(long)pdesc->desc.offset, fops);
     }
 
     for (i = 0; i < kvm_vcpu_stats_header.num_desc; ++i) {
         pdesc = &kvm_vcpu_stats_desc[i];
         if (kvm_stats_debugfs_mode(pdesc) & 0222)
             fops = &vcpu_stat_fops;
         else
             fops = &vcpu_stat_readonly_fops;
         debugfs_create_file(pdesc->name, kvm_stats_debugfs_mode(pdesc),
                 kvm_debugfs_dir,
                 (void *)(long)pdesc->desc.offset, fops);
     }
 }
 
 static int kvm_suspend(void)
 {
     if (kvm_usage_count)
         hardware_disable_nolock(NULL);
     return 0;
 }
 
 static void kvm_resume(void)
 {
     if (kvm_usage_count) {
         lockdep_assert_not_held(&kvm_count_lock);
         hardware_enable_nolock(NULL);
     }
 }
 
 static struct syscore_ops kvm_syscore_ops = {
     .suspend = kvm_suspend,
     .resume = kvm_resume,
 };
 
 static inline
 struct kvm_vcpu *preempt_notifier_to_vcpu(struct preempt_notifier *pn)
 {
     return container_of(pn, struct kvm_vcpu, preempt_notifier);
 }
 
 static void kvm_sched_in(struct preempt_notifier *pn, int cpu)
 {
     struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);
 
     WRITE_ONCE(vcpu->preempted, false);
     WRITE_ONCE(vcpu->ready, false);
 
     __this_cpu_write(kvm_running_vcpu, vcpu);
     kvm_arch_sched_in(vcpu, cpu);
     kvm_arch_vcpu_load(vcpu, cpu);
 }
 
 static void kvm_sched_out(struct preempt_notifier *pn,
               struct task_struct *next)
 {
     struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);
 
     if (current->on_rq) {
         WRITE_ONCE(vcpu->preempted, true);
         WRITE_ONCE(vcpu->ready, true);
     }
     kvm_arch_vcpu_put(vcpu);
     __this_cpu_write(kvm_running_vcpu, NULL);
 }
 
 /**
  * kvm_get_running_vcpu - get the vcpu running on the current CPU.
  *
  * We can disable preemption locally around accessing the per-CPU variable,
  * and use the resolved vcpu pointer after enabling preemption again,
  * because even if the current thread is migrated to another CPU, reading
  * the per-CPU value later will give us the same value as we update the
  * per-CPU variable in the preempt notifier handlers.
  */
 struct kvm_vcpu *kvm_get_running_vcpu(void)
 {
     struct kvm_vcpu *vcpu;
 
     preempt_disable();
     vcpu = __this_cpu_read(kvm_running_vcpu);
     preempt_enable();
 
     return vcpu;
 }
 EXPORT_SYMBOL_GPL(kvm_get_running_vcpu);
 
 /**
  * kvm_get_running_vcpus - get the per-CPU array of currently running vcpus.
  */
 struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
 {
         return &kvm_running_vcpu;
 }
 
 #ifdef CONFIG_GUEST_PERF_EVENTS
 static unsigned int kvm_guest_state(void)
 {
     struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
     unsigned int state;
 
     if (!kvm_arch_pmi_in_guest(vcpu))
         return 0;
 
     state = PERF_GUEST_ACTIVE;
     if (!kvm_arch_vcpu_in_kernel(vcpu))
         state |= PERF_GUEST_USER;
 
     return state;
 }
 
 static unsigned long kvm_guest_get_ip(void)
 {
     struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
     /* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
     if (WARN_ON_ONCE(!kvm_arch_pmi_in_guest(vcpu)))
         return 0;
 
     return kvm_arch_vcpu_get_ip(vcpu);
 }
 
 static struct perf_guest_info_callbacks kvm_guest_cbs = {
     .state          = kvm_guest_state,
     .get_ip         = kvm_guest_get_ip,
     .handle_intel_pt_intr   = NULL,
 };
 
 void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void))
 {
     kvm_guest_cbs.handle_intel_pt_intr = pt_intr_handler;
     perf_register_guest_info_callbacks(&kvm_guest_cbs);
 }
 void kvm_unregister_perf_callbacks(void)
 {
     perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
 }
 #endif
 
 struct kvm_cpu_compat_check {
     void *opaque;
     int *ret;
 };
 
 static void check_processor_compat(void *data)
 {
     struct kvm_cpu_compat_check *c = data;
 
     *c->ret = kvm_arch_check_processor_compat(c->opaque);
 }
 
 int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
           struct module *module)
 {
     struct kvm_cpu_compat_check c;
     int r;
     int cpu;
 
     r = kvm_arch_init(opaque);
     if (r)
         goto out_fail;
 
     /*
      * kvm_arch_init makes sure there's at most one caller
      * for architectures that support multiple implementations,
      * like intel and amd on x86.
      * kvm_arch_init must be called before kvm_irqfd_init to avoid creating
      * conflicts in case kvm is already setup for another implementation.
      */
     r = kvm_irqfd_init();
     if (r)
         goto out_irqfd;
 
     if (!zalloc_cpumask_var(&cpus_hardware_enabled, GFP_KERNEL)) {
         r = -ENOMEM;
         goto out_free_0;
     }
 
     r = kvm_arch_hardware_setup(opaque);
     if (r < 0)
         goto out_free_1;
 
     c.ret = &r;
     c.opaque = opaque;
     for_each_online_cpu(cpu) {
         smp_call_function_single(cpu, check_processor_compat, &c, 1);
         if (r < 0)
             goto out_free_2;
     }
 
     r = cpuhp_setup_state_nocalls(CPUHP_AP_KVM_STARTING, "kvm/cpu:starting",
                       kvm_starting_cpu, kvm_dying_cpu);
     if (r)
         goto out_free_2;
     register_reboot_notifier(&kvm_reboot_notifier);
 
     /* A kmem cache lets us meet the alignment requirements of fx_save. */
     if (!vcpu_align)
         vcpu_align = __alignof__(struct kvm_vcpu);
     kvm_vcpu_cache =
         kmem_cache_create_usercopy("kvm_vcpu", vcpu_size, vcpu_align,
                        SLAB_ACCOUNT,
                        offsetof(struct kvm_vcpu, arch),
                        offsetofend(struct kvm_vcpu, stats_id)
                        - offsetof(struct kvm_vcpu, arch),
                        NULL);
     if (!kvm_vcpu_cache) {
         r = -ENOMEM;
         goto out_free_3;
     }
 
     for_each_possible_cpu(cpu) {
         if (!alloc_cpumask_var_node(&per_cpu(cpu_kick_mask, cpu),
                         GFP_KERNEL, cpu_to_node(cpu))) {
             r = -ENOMEM;
             goto out_free_4;
         }
     }
 
     r = kvm_async_pf_init();
     if (r)
         goto out_free_5;
 
     kvm_chardev_ops.owner = module;
 
     r = misc_register(&kvm_dev);
     if (r) {
         pr_err("kvm: misc device register failed\n");
         goto out_unreg;
     }
 
     register_syscore_ops(&kvm_syscore_ops);
 
     kvm_preempt_ops.sched_in = kvm_sched_in;
     kvm_preempt_ops.sched_out = kvm_sched_out;
 
     kvm_init_debug();
 
     r = kvm_vfio_ops_init();
     WARN_ON(r);
 
     return 0;
 
 out_unreg:
     kvm_async_pf_deinit();
 out_free_5:
     for_each_possible_cpu(cpu)
         free_cpumask_var(per_cpu(cpu_kick_mask, cpu));
 out_free_4:
     kmem_cache_destroy(kvm_vcpu_cache);
 out_free_3:
     unregister_reboot_notifier(&kvm_reboot_notifier);
     cpuhp_remove_state_nocalls(CPUHP_AP_KVM_STARTING);
 out_free_2:
     kvm_arch_hardware_unsetup();
 out_free_1:
     free_cpumask_var(cpus_hardware_enabled);
 out_free_0:
     kvm_irqfd_exit();
 out_irqfd:
     kvm_arch_exit();
 out_fail:
     return r;
 }
 EXPORT_SYMBOL_GPL(kvm_init);
 
 void kvm_exit(void)
 {
     int cpu;
 
     debugfs_remove_recursive(kvm_debugfs_dir);
     misc_deregister(&kvm_dev);
     for_each_possible_cpu(cpu)
         free_cpumask_var(per_cpu(cpu_kick_mask, cpu));
     kmem_cache_destroy(kvm_vcpu_cache);
     kvm_async_pf_deinit();
     unregister_syscore_ops(&kvm_syscore_ops);
     unregister_reboot_notifier(&kvm_reboot_notifier);
     cpuhp_remove_state_nocalls(CPUHP_AP_KVM_STARTING);
     on_each_cpu(hardware_disable_nolock, NULL, 1);
     kvm_arch_hardware_unsetup();
     kvm_arch_exit();
     kvm_irqfd_exit();
     free_cpumask_var(cpus_hardware_enabled);
     kvm_vfio_ops_exit();
 }
 EXPORT_SYMBOL_GPL(kvm_exit);
 
 struct kvm_vm_worker_thread_context {
     struct kvm *kvm;
     struct task_struct *parent;
     struct completion init_done;
     kvm_vm_thread_fn_t thread_fn;
     uintptr_t data;
     int err;
 };
 
 static int kvm_vm_worker_thread(void *context)
 {
     /*
      * The init_context is allocated on the stack of the parent thread, so
      * we have to locally copy anything that is needed beyond initialization
      */
     struct kvm_vm_worker_thread_context *init_context = context;
     struct task_struct *parent;
     struct kvm *kvm = init_context->kvm;
     kvm_vm_thread_fn_t thread_fn = init_context->thread_fn;
     uintptr_t data = init_context->data;
     int err;
 
     err = kthread_park(current);
     /* kthread_park(current) is never supposed to return an error */
     WARN_ON(err != 0);
     if (err)
         goto init_complete;
 
     err = cgroup_attach_task_all(init_context->parent, current);
     if (err) {
         kvm_err("%s: cgroup_attach_task_all failed with err %d\n",
             __func__, err);
         goto init_complete;
     }
 
     set_user_nice(current, task_nice(init_context->parent));
 
 init_complete:
     init_context->err = err;
     complete(&init_context->init_done);
     init_context = NULL;
 
     if (err)
         goto out;
 
     /* Wait to be woken up by the spawner before proceeding. */
     kthread_parkme();
 
     if (!kthread_should_stop())
         err = thread_fn(kvm, data);
 
 out:
     /*
      * Move kthread back to its original cgroup to prevent it lingering in
      * the cgroup of the VM process, after the latter finishes its
      * execution.
      *
      * kthread_stop() waits on the 'exited' completion condition which is
      * set in exit_mm(), via mm_release(), in do_exit(). However, the
      * kthread is removed from the cgroup in the cgroup_exit() which is
      * called after the exit_mm(). This causes the kthread_stop() to return
      * before the kthread actually quits the cgroup.
      */
     rcu_read_lock();
     parent = rcu_dereference(current->real_parent);
     get_task_struct(parent);
     rcu_read_unlock();
     cgroup_attach_task_all(parent, current);
     put_task_struct(parent);
 
     return err;
 }
 
 int kvm_vm_create_worker_thread(struct kvm *kvm, kvm_vm_thread_fn_t thread_fn,
                 uintptr_t data, const char *name,
                 struct task_struct **thread_ptr)
 {
     struct kvm_vm_worker_thread_context init_context = {};
     struct task_struct *thread;
 
     *thread_ptr = NULL;
     init_context.kvm = kvm;
     init_context.parent = current;
     init_context.thread_fn = thread_fn;
     init_context.data = data;
     init_completion(&init_context.init_done);
 
     thread = kthread_run(kvm_vm_worker_thread, &init_context,
                  "%s-%d", name, task_pid_nr(current));
     if (IS_ERR(thread))
         return PTR_ERR(thread);
 
     /* kthread_run is never supposed to return NULL */
     WARN_ON(thread == NULL);
 
     wait_for_completion(&init_context.init_done);
 
     if (!init_context.err)
         *thread_ptr = thread;
 
     return init_context.err;
 }