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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
 /*
  * kvm eventfd support - use eventfd objects to signal various KVM events
  *
  * Copyright 2009 Novell.  All Rights Reserved.
  * Copyright 2010 Red Hat, Inc. and/or its affiliates.
  *
  * Author:
  *  Gregory Haskins <ghaskins@novell.com>
  */
 
 #include <linux/kvm_host.h>
 #include <linux/kvm.h>
 #include <linux/kvm_irqfd.h>
 #include <linux/workqueue.h>
 #include <linux/syscalls.h>
 #include <linux/wait.h>
 #include <linux/poll.h>
 #include <linux/file.h>
 #include <linux/list.h>
 #include <linux/eventfd.h>
 #include <linux/kernel.h>
 #include <linux/srcu.h>
 #include <linux/slab.h>
 #include <linux/seqlock.h>
 #include <linux/irqbypass.h>
 #include <trace/events/kvm.h>
 
 #include <kvm/iodev.h>
 
 #ifdef CONFIG_HAVE_KVM_IRQFD
 
 static struct workqueue_struct *irqfd_cleanup_wq;
 
 bool __attribute__((weak))
 kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args)
 {
     return true;
 }
 
 static void
 irqfd_inject(struct work_struct *work)
 {
     struct kvm_kernel_irqfd *irqfd =
         container_of(work, struct kvm_kernel_irqfd, inject);
     struct kvm *kvm = irqfd->kvm;
 
     if (!irqfd->resampler) {
         kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1,
                 false);
         kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0,
                 false);
     } else
         kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
                 irqfd->gsi, 1, false);
 }
 
 /*
  * Since resampler irqfds share an IRQ source ID, we de-assert once
  * then notify all of the resampler irqfds using this GSI.  We can't
  * do multiple de-asserts or we risk racing with incoming re-asserts.
  */
 static void
 irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian)
 {
     struct kvm_kernel_irqfd_resampler *resampler;
     struct kvm *kvm;
     struct kvm_kernel_irqfd *irqfd;
     int idx;
 
     resampler = container_of(kian,
             struct kvm_kernel_irqfd_resampler, notifier);
     kvm = resampler->kvm;
 
     kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
             resampler->notifier.gsi, 0, false);
 
     idx = srcu_read_lock(&kvm->irq_srcu);
 
     list_for_each_entry_srcu(irqfd, &resampler->list, resampler_link,
         srcu_read_lock_held(&kvm->irq_srcu))
         eventfd_signal(irqfd->resamplefd, 1);
 
     srcu_read_unlock(&kvm->irq_srcu, idx);
 }
 
 static void
 irqfd_resampler_shutdown(struct kvm_kernel_irqfd *irqfd)
 {
     struct kvm_kernel_irqfd_resampler *resampler = irqfd->resampler;
     struct kvm *kvm = resampler->kvm;
 
     mutex_lock(&kvm->irqfds.resampler_lock);
 
     list_del_rcu(&irqfd->resampler_link);
     synchronize_srcu(&kvm->irq_srcu);
 
     if (list_empty(&resampler->list)) {
         list_del(&resampler->link);
         kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier);
         kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID,
                 resampler->notifier.gsi, 0, false);
         kfree(resampler);
     }
 
     mutex_unlock(&kvm->irqfds.resampler_lock);
 }
 
 /*
  * Race-free decouple logic (ordering is critical)
  */
 static void
 irqfd_shutdown(struct work_struct *work)
 {
     struct kvm_kernel_irqfd *irqfd =
         container_of(work, struct kvm_kernel_irqfd, shutdown);
     struct kvm *kvm = irqfd->kvm;
     u64 cnt;
 
     /* Make sure irqfd has been initialized in assign path. */
     synchronize_srcu(&kvm->irq_srcu);
 
     /*
      * Synchronize with the wait-queue and unhook ourselves to prevent
      * further events.
      */
     eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
 
     /*
      * We know no new events will be scheduled at this point, so block
      * until all previously outstanding events have completed
      */
     flush_work(&irqfd->inject);
 
     if (irqfd->resampler) {
         irqfd_resampler_shutdown(irqfd);
         eventfd_ctx_put(irqfd->resamplefd);
     }
 
     /*
      * It is now safe to release the object's resources
      */
 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
     irq_bypass_unregister_consumer(&irqfd->consumer);
 #endif
     eventfd_ctx_put(irqfd->eventfd);
     kfree(irqfd);
 }
 
 
 /* assumes kvm->irqfds.lock is held */
 static bool
 irqfd_is_active(struct kvm_kernel_irqfd *irqfd)
 {
     return list_empty(&irqfd->list) ? false : true;
 }
 
 /*
  * Mark the irqfd as inactive and schedule it for removal
  *
  * assumes kvm->irqfds.lock is held
  */
 static void
 irqfd_deactivate(struct kvm_kernel_irqfd *irqfd)
 {
     BUG_ON(!irqfd_is_active(irqfd));
 
     list_del_init(&irqfd->list);
 
     queue_work(irqfd_cleanup_wq, &irqfd->shutdown);
 }
 
 int __attribute__((weak)) kvm_arch_set_irq_inatomic(
                 struct kvm_kernel_irq_routing_entry *irq,
                 struct kvm *kvm, int irq_source_id,
                 int level,
                 bool line_status)
 {
     return -EWOULDBLOCK;
 }
 
 /*
  * Called with wqh->lock held and interrupts disabled
  */
 static int
 irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
 {
     struct kvm_kernel_irqfd *irqfd =
         container_of(wait, struct kvm_kernel_irqfd, wait);
     __poll_t flags = key_to_poll(key);
     struct kvm_kernel_irq_routing_entry irq;
     struct kvm *kvm = irqfd->kvm;
     unsigned seq;
     int idx;
     int ret = 0;
 
     if (flags & EPOLLIN) {
         u64 cnt;
         eventfd_ctx_do_read(irqfd->eventfd, &cnt);
 
         idx = srcu_read_lock(&kvm->irq_srcu);
         do {
             seq = read_seqcount_begin(&irqfd->irq_entry_sc);
             irq = irqfd->irq_entry;
         } while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
         /* An event has been signaled, inject an interrupt */
         if (kvm_arch_set_irq_inatomic(&irq, kvm,
                           KVM_USERSPACE_IRQ_SOURCE_ID, 1,
                           false) == -EWOULDBLOCK)
             schedule_work(&irqfd->inject);
         srcu_read_unlock(&kvm->irq_srcu, idx);
         ret = 1;
     }
 
     if (flags & EPOLLHUP) {
         /* The eventfd is closing, detach from KVM */
         unsigned long iflags;
 
         spin_lock_irqsave(&kvm->irqfds.lock, iflags);
 
         /*
          * We must check if someone deactivated the irqfd before
          * we could acquire the irqfds.lock since the item is
          * deactivated from the KVM side before it is unhooked from
          * the wait-queue.  If it is already deactivated, we can
          * simply return knowing the other side will cleanup for us.
          * We cannot race against the irqfd going away since the
          * other side is required to acquire wqh->lock, which we hold
          */
         if (irqfd_is_active(irqfd))
             irqfd_deactivate(irqfd);
 
         spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
     }
 
     return ret;
 }
 
 static void
 irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
             poll_table *pt)
 {
     struct kvm_kernel_irqfd *irqfd =
         container_of(pt, struct kvm_kernel_irqfd, pt);
     add_wait_queue_priority(wqh, &irqfd->wait);
 }
 
 /* Must be called under irqfds.lock */
 static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
 {
     struct kvm_kernel_irq_routing_entry *e;
     struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
     int n_entries;
 
     n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
 
     write_seqcount_begin(&irqfd->irq_entry_sc);
 
     e = entries;
     if (n_entries == 1)
         irqfd->irq_entry = *e;
     else
         irqfd->irq_entry.type = 0;
 
     write_seqcount_end(&irqfd->irq_entry_sc);
 }
 
 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
 void __attribute__((weak)) kvm_arch_irq_bypass_stop(
                 struct irq_bypass_consumer *cons)
 {
 }
 
 void __attribute__((weak)) kvm_arch_irq_bypass_start(
                 struct irq_bypass_consumer *cons)
 {
 }
 
 int  __attribute__((weak)) kvm_arch_update_irqfd_routing(
                 struct kvm *kvm, unsigned int host_irq,
                 uint32_t guest_irq, bool set)
 {
     return 0;
 }
 
 bool __attribute__((weak)) kvm_arch_irqfd_route_changed(
                 struct kvm_kernel_irq_routing_entry *old,
                 struct kvm_kernel_irq_routing_entry *new)
 {
     return true;
 }
 #endif
 
 static int
 kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
 {
     struct kvm_kernel_irqfd *irqfd, *tmp;
     struct fd f;
     struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL;
     int ret;
     __poll_t events;
     int idx;
 
     if (!kvm_arch_intc_initialized(kvm))
         return -EAGAIN;
 
     if (!kvm_arch_irqfd_allowed(kvm, args))
         return -EINVAL;
 
     irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL_ACCOUNT);
     if (!irqfd)
         return -ENOMEM;
 
     irqfd->kvm = kvm;
     irqfd->gsi = args->gsi;
     INIT_LIST_HEAD(&irqfd->list);
     INIT_WORK(&irqfd->inject, irqfd_inject);
     INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
     seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
 
     f = fdget(args->fd);
     if (!f.file) {
         ret = -EBADF;
         goto out;
     }
 
     eventfd = eventfd_ctx_fileget(f.file);
     if (IS_ERR(eventfd)) {
         ret = PTR_ERR(eventfd);
         goto fail;
     }
 
     irqfd->eventfd = eventfd;
 
     if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) {
         struct kvm_kernel_irqfd_resampler *resampler;
 
         resamplefd = eventfd_ctx_fdget(args->resamplefd);
         if (IS_ERR(resamplefd)) {
             ret = PTR_ERR(resamplefd);
             goto fail;
         }
 
         irqfd->resamplefd = resamplefd;
         INIT_LIST_HEAD(&irqfd->resampler_link);
 
         mutex_lock(&kvm->irqfds.resampler_lock);
 
         list_for_each_entry(resampler,
                     &kvm->irqfds.resampler_list, link) {
             if (resampler->notifier.gsi == irqfd->gsi) {
                 irqfd->resampler = resampler;
                 break;
             }
         }
 
         if (!irqfd->resampler) {
             resampler = kzalloc(sizeof(*resampler),
                         GFP_KERNEL_ACCOUNT);
             if (!resampler) {
                 ret = -ENOMEM;
                 mutex_unlock(&kvm->irqfds.resampler_lock);
                 goto fail;
             }
 
             resampler->kvm = kvm;
             INIT_LIST_HEAD(&resampler->list);
             resampler->notifier.gsi = irqfd->gsi;
             resampler->notifier.irq_acked = irqfd_resampler_ack;
             INIT_LIST_HEAD(&resampler->link);
 
             list_add(&resampler->link, &kvm->irqfds.resampler_list);
             kvm_register_irq_ack_notifier(kvm,
                               &resampler->notifier);
             irqfd->resampler = resampler;
         }
 
         list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list);
         synchronize_srcu(&kvm->irq_srcu);
 
         mutex_unlock(&kvm->irqfds.resampler_lock);
     }
 
     /*
      * Install our own custom wake-up handling so we are notified via
      * a callback whenever someone signals the underlying eventfd
      */
     init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
     init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
 
     spin_lock_irq(&kvm->irqfds.lock);
 
     ret = 0;
     list_for_each_entry(tmp, &kvm->irqfds.items, list) {
         if (irqfd->eventfd != tmp->eventfd)
             continue;
         /* This fd is used for another irq already. */
         ret = -EBUSY;
         spin_unlock_irq(&kvm->irqfds.lock);
         goto fail;
     }
 
     idx = srcu_read_lock(&kvm->irq_srcu);
     irqfd_update(kvm, irqfd);
 
     list_add_tail(&irqfd->list, &kvm->irqfds.items);
 
     spin_unlock_irq(&kvm->irqfds.lock);
 
     /*
      * Check if there was an event already pending on the eventfd
      * before we registered, and trigger it as if we didn't miss it.
      */
     events = vfs_poll(f.file, &irqfd->pt);
 
     if (events & EPOLLIN)
         schedule_work(&irqfd->inject);
 
 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
     if (kvm_arch_has_irq_bypass()) {
         irqfd->consumer.token = (void *)irqfd->eventfd;
         irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
         irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
         irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
         irqfd->consumer.start = kvm_arch_irq_bypass_start;
         ret = irq_bypass_register_consumer(&irqfd->consumer);
         if (ret)
             pr_info("irq bypass consumer (token %p) registration fails: %d\n",
                 irqfd->consumer.token, ret);
     }
 #endif
 
     srcu_read_unlock(&kvm->irq_srcu, idx);
 
     /*
      * do not drop the file until the irqfd is fully initialized, otherwise
      * we might race against the EPOLLHUP
      */
     fdput(f);
     return 0;
 
 fail:
     if (irqfd->resampler)
         irqfd_resampler_shutdown(irqfd);
 
     if (resamplefd && !IS_ERR(resamplefd))
         eventfd_ctx_put(resamplefd);
 
     if (eventfd && !IS_ERR(eventfd))
         eventfd_ctx_put(eventfd);
 
     fdput(f);
 
 out:
     kfree(irqfd);
     return ret;
 }
 
 bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
 {
     struct kvm_irq_ack_notifier *kian;
     int gsi, idx;
 
     idx = srcu_read_lock(&kvm->irq_srcu);
     gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
     if (gsi != -1)
         hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
                       link, srcu_read_lock_held(&kvm->irq_srcu))
             if (kian->gsi == gsi) {
                 srcu_read_unlock(&kvm->irq_srcu, idx);
                 return true;
             }
 
     srcu_read_unlock(&kvm->irq_srcu, idx);
 
     return false;
 }
 EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
 
 void kvm_notify_acked_gsi(struct kvm *kvm, int gsi)
 {
     struct kvm_irq_ack_notifier *kian;
 
     hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list,
                   link, srcu_read_lock_held(&kvm->irq_srcu))
         if (kian->gsi == gsi)
             kian->irq_acked(kian);
 }
 
 void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
 {
     int gsi, idx;
 
     trace_kvm_ack_irq(irqchip, pin);
 
     idx = srcu_read_lock(&kvm->irq_srcu);
     gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
     if (gsi != -1)
         kvm_notify_acked_gsi(kvm, gsi);
     srcu_read_unlock(&kvm->irq_srcu, idx);
 }
 
 void kvm_register_irq_ack_notifier(struct kvm *kvm,
                    struct kvm_irq_ack_notifier *kian)
 {
     mutex_lock(&kvm->irq_lock);
     hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
     mutex_unlock(&kvm->irq_lock);
     kvm_arch_post_irq_ack_notifier_list_update(kvm);
 }
 
 void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
                     struct kvm_irq_ack_notifier *kian)
 {
     mutex_lock(&kvm->irq_lock);
     hlist_del_init_rcu(&kian->link);
     mutex_unlock(&kvm->irq_lock);
     synchronize_srcu(&kvm->irq_srcu);
     kvm_arch_post_irq_ack_notifier_list_update(kvm);
 }
 #endif
 
 void
 kvm_eventfd_init(struct kvm *kvm)
 {
 #ifdef CONFIG_HAVE_KVM_IRQFD
     spin_lock_init(&kvm->irqfds.lock);
     INIT_LIST_HEAD(&kvm->irqfds.items);
     INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
     mutex_init(&kvm->irqfds.resampler_lock);
 #endif
     INIT_LIST_HEAD(&kvm->ioeventfds);
 }
 
 #ifdef CONFIG_HAVE_KVM_IRQFD
 /*
  * shutdown any irqfd's that match fd+gsi
  */
 static int
 kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
 {
     struct kvm_kernel_irqfd *irqfd, *tmp;
     struct eventfd_ctx *eventfd;
 
     eventfd = eventfd_ctx_fdget(args->fd);
     if (IS_ERR(eventfd))
         return PTR_ERR(eventfd);
 
     spin_lock_irq(&kvm->irqfds.lock);
 
     list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) {
         if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) {
             /*
              * This clearing of irq_entry.type is needed for when
              * another thread calls kvm_irq_routing_update before
              * we flush workqueue below (we synchronize with
              * kvm_irq_routing_update using irqfds.lock).
              */
             write_seqcount_begin(&irqfd->irq_entry_sc);
             irqfd->irq_entry.type = 0;
             write_seqcount_end(&irqfd->irq_entry_sc);
             irqfd_deactivate(irqfd);
         }
     }
 
     spin_unlock_irq(&kvm->irqfds.lock);
     eventfd_ctx_put(eventfd);
 
     /*
      * Block until we know all outstanding shutdown jobs have completed
      * so that we guarantee there will not be any more interrupts on this
      * gsi once this deassign function returns.
      */
     flush_workqueue(irqfd_cleanup_wq);
 
     return 0;
 }
 
 int
 kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
 {
     if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
         return -EINVAL;
 
     if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
         return kvm_irqfd_deassign(kvm, args);
 
     return kvm_irqfd_assign(kvm, args);
 }
 
 /*
  * This function is called as the kvm VM fd is being released. Shutdown all
  * irqfds that still remain open
  */
 void
 kvm_irqfd_release(struct kvm *kvm)
 {
     struct kvm_kernel_irqfd *irqfd, *tmp;
 
     spin_lock_irq(&kvm->irqfds.lock);
 
     list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list)
         irqfd_deactivate(irqfd);
 
     spin_unlock_irq(&kvm->irqfds.lock);
 
     /*
      * Block until we know all outstanding shutdown jobs have completed
      * since we do not take a kvm* reference.
      */
     flush_workqueue(irqfd_cleanup_wq);
 
 }
 
 /*
  * Take note of a change in irq routing.
  * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards.
  */
 void kvm_irq_routing_update(struct kvm *kvm)
 {
     struct kvm_kernel_irqfd *irqfd;
 
     spin_lock_irq(&kvm->irqfds.lock);
 
     list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
         /* Under irqfds.lock, so can read irq_entry safely */
         struct kvm_kernel_irq_routing_entry old = irqfd->irq_entry;
 #endif
 
         irqfd_update(kvm, irqfd);
 
 #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
         if (irqfd->producer &&
             kvm_arch_irqfd_route_changed(&old, &irqfd->irq_entry)) {
             int ret = kvm_arch_update_irqfd_routing(
                     irqfd->kvm, irqfd->producer->irq,
                     irqfd->gsi, 1);
             WARN_ON(ret);
         }
 #endif
     }
 
     spin_unlock_irq(&kvm->irqfds.lock);
 }
 
 /*
  * create a host-wide workqueue for issuing deferred shutdown requests
  * aggregated from all vm* instances. We need our own isolated
  * queue to ease flushing work items when a VM exits.
  */
 int kvm_irqfd_init(void)
 {
     irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);
     if (!irqfd_cleanup_wq)
         return -ENOMEM;
 
     return 0;
 }
 
 void kvm_irqfd_exit(void)
 {
     destroy_workqueue(irqfd_cleanup_wq);
 }
 #endif
 
 /*
  * --------------------------------------------------------------------
  * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
  *
  * userspace can register a PIO/MMIO address with an eventfd for receiving
  * notification when the memory has been touched.
  * --------------------------------------------------------------------
  */
 
 struct _ioeventfd {
     struct list_head     list;
     u64                  addr;
     int                  length;
     struct eventfd_ctx  *eventfd;
     u64                  datamatch;
     struct kvm_io_device dev;
     u8                   bus_idx;
     bool                 wildcard;
 };
 
 static inline struct _ioeventfd *
 to_ioeventfd(struct kvm_io_device *dev)
 {
     return container_of(dev, struct _ioeventfd, dev);
 }
 
 static void
 ioeventfd_release(struct _ioeventfd *p)
 {
     eventfd_ctx_put(p->eventfd);
     list_del(&p->list);
     kfree(p);
 }
 
 static bool
 ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
 {
     u64 _val;
 
     if (addr != p->addr)
         /* address must be precise for a hit */
         return false;
 
     if (!p->length)
         /* length = 0 means only look at the address, so always a hit */
         return true;
 
     if (len != p->length)
         /* address-range must be precise for a hit */
         return false;
 
     if (p->wildcard)
         /* all else equal, wildcard is always a hit */
         return true;
 
     /* otherwise, we have to actually compare the data */
 
     BUG_ON(!IS_ALIGNED((unsigned long)val, len));
 
     switch (len) {
     case 1:
         _val = *(u8 *)val;
         break;
     case 2:
         _val = *(u16 *)val;
         break;
     case 4:
         _val = *(u32 *)val;
         break;
     case 8:
         _val = *(u64 *)val;
         break;
     default:
         return false;
     }
 
     return _val == p->datamatch;
 }
 
 /* MMIO/PIO writes trigger an event if the addr/val match */
 static int
 ioeventfd_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, gpa_t addr,
         int len, const void *val)
 {
     struct _ioeventfd *p = to_ioeventfd(this);
 
     if (!ioeventfd_in_range(p, addr, len, val))
         return -EOPNOTSUPP;
 
     eventfd_signal(p->eventfd, 1);
     return 0;
 }
 
 /*
  * This function is called as KVM is completely shutting down.  We do not
  * need to worry about locking just nuke anything we have as quickly as possible
  */
 static void
 ioeventfd_destructor(struct kvm_io_device *this)
 {
     struct _ioeventfd *p = to_ioeventfd(this);
 
     ioeventfd_release(p);
 }
 
 static const struct kvm_io_device_ops ioeventfd_ops = {
     .write      = ioeventfd_write,
     .destructor = ioeventfd_destructor,
 };
 
 /* assumes kvm->slots_lock held */
 static bool
 ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
 {
     struct _ioeventfd *_p;
 
     list_for_each_entry(_p, &kvm->ioeventfds, list)
         if (_p->bus_idx == p->bus_idx &&
             _p->addr == p->addr &&
             (!_p->length || !p->length ||
              (_p->length == p->length &&
               (_p->wildcard || p->wildcard ||
                _p->datamatch == p->datamatch))))
             return true;
 
     return false;
 }
 
 static enum kvm_bus ioeventfd_bus_from_flags(__u32 flags)
 {
     if (flags & KVM_IOEVENTFD_FLAG_PIO)
         return KVM_PIO_BUS;
     if (flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY)
         return KVM_VIRTIO_CCW_NOTIFY_BUS;
     return KVM_MMIO_BUS;
 }
 
 static int kvm_assign_ioeventfd_idx(struct kvm *kvm,
                 enum kvm_bus bus_idx,
                 struct kvm_ioeventfd *args)
 {
 
     struct eventfd_ctx *eventfd;
     struct _ioeventfd *p;
     int ret;
 
     eventfd = eventfd_ctx_fdget(args->fd);
     if (IS_ERR(eventfd))
         return PTR_ERR(eventfd);
 
     p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT);
     if (!p) {
         ret = -ENOMEM;
         goto fail;
     }
 
     INIT_LIST_HEAD(&p->list);
     p->addr    = args->addr;
     p->bus_idx = bus_idx;
     p->length  = args->len;
     p->eventfd = eventfd;
 
     /* The datamatch feature is optional, otherwise this is a wildcard */
     if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
         p->datamatch = args->datamatch;
     else
         p->wildcard = true;
 
     mutex_lock(&kvm->slots_lock);
 
     /* Verify that there isn't a match already */
     if (ioeventfd_check_collision(kvm, p)) {
         ret = -EEXIST;
         goto unlock_fail;
     }
 
     kvm_iodevice_init(&p->dev, &ioeventfd_ops);
 
     ret = kvm_io_bus_register_dev(kvm, bus_idx, p->addr, p->length,
                       &p->dev);
     if (ret < 0)
         goto unlock_fail;
 
     kvm_get_bus(kvm, bus_idx)->ioeventfd_count++;
     list_add_tail(&p->list, &kvm->ioeventfds);
 
     mutex_unlock(&kvm->slots_lock);
 
     return 0;
 
 unlock_fail:
     mutex_unlock(&kvm->slots_lock);
 
 fail:
     kfree(p);
     eventfd_ctx_put(eventfd);
 
     return ret;
 }
 
 static int
 kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
                struct kvm_ioeventfd *args)
 {
     struct _ioeventfd        *p, *tmp;
     struct eventfd_ctx       *eventfd;
     struct kvm_io_bus    *bus;
     int                       ret = -ENOENT;
     bool                      wildcard;
 
     eventfd = eventfd_ctx_fdget(args->fd);
     if (IS_ERR(eventfd))
         return PTR_ERR(eventfd);
 
     wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
 
     mutex_lock(&kvm->slots_lock);
 
     list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
 
         if (p->bus_idx != bus_idx ||
             p->eventfd != eventfd  ||
             p->addr != args->addr  ||
             p->length != args->len ||
             p->wildcard != wildcard)
             continue;
 
         if (!p->wildcard && p->datamatch != args->datamatch)
             continue;
 
         kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
         bus = kvm_get_bus(kvm, bus_idx);
         if (bus)
             bus->ioeventfd_count--;
         ioeventfd_release(p);
         ret = 0;
         break;
     }
 
     mutex_unlock(&kvm->slots_lock);
 
     eventfd_ctx_put(eventfd);
 
     return ret;
 }
 
 static int kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 {
     enum kvm_bus bus_idx = ioeventfd_bus_from_flags(args->flags);
     int ret = kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
 
     if (!args->len && bus_idx == KVM_MMIO_BUS)
         kvm_deassign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
 
     return ret;
 }
 
 static int
 kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 {
     enum kvm_bus              bus_idx;
     int ret;
 
     bus_idx = ioeventfd_bus_from_flags(args->flags);
     /* must be natural-word sized, or 0 to ignore length */
     switch (args->len) {
     case 0:
     case 1:
     case 2:
     case 4:
     case 8:
         break;
     default:
         return -EINVAL;
     }
 
     /* check for range overflow */
     if (args->addr + args->len < args->addr)
         return -EINVAL;
 
     /* check for extra flags that we don't understand */
     if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
         return -EINVAL;
 
     /* ioeventfd with no length can't be combined with DATAMATCH */
     if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH))
         return -EINVAL;
 
     ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args);
     if (ret)
         goto fail;
 
     /* When length is ignored, MMIO is also put on a separate bus, for
      * faster lookups.
      */
     if (!args->len && bus_idx == KVM_MMIO_BUS) {
         ret = kvm_assign_ioeventfd_idx(kvm, KVM_FAST_MMIO_BUS, args);
         if (ret < 0)
             goto fast_fail;
     }
 
     return 0;
 
 fast_fail:
     kvm_deassign_ioeventfd_idx(kvm, bus_idx, args);
 fail:
     return ret;
 }
 
 int
 kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 {
     if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
         return kvm_deassign_ioeventfd(kvm, args);
 
     return kvm_assign_ioeventfd(kvm, args);
 }

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