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 // SPDX-License-Identifier: GPL-2.0
 /*
  *  KVM guest address space mapping code
  *
  *    Copyright IBM Corp. 2007, 2020
  *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
  *       David Hildenbrand <david@redhat.com>
  *       Janosch Frank <frankja@linux.vnet.ibm.com>
  */
 
 #include <linux/kernel.h>
 #include <linux/pagewalk.h>
 #include <linux/swap.h>
 #include <linux/smp.h>
 #include <linux/spinlock.h>
 #include <linux/slab.h>
 #include <linux/swapops.h>
 #include <linux/ksm.h>
 #include <linux/mman.h>
 #include <linux/pgtable.h>
 
 #include <asm/pgalloc.h>
 #include <asm/gmap.h>
 #include <asm/tlb.h>
 
 #define GMAP_SHADOW_FAKE_TABLE 1ULL
 
 /**
  * gmap_alloc - allocate and initialize a guest address space
  * @limit: maximum address of the gmap address space
  *
  * Returns a guest address space structure.
  */
 static struct gmap *gmap_alloc(unsigned long limit)
 {
     struct gmap *gmap;
     struct page *page;
     unsigned long *table;
     unsigned long etype, atype;
 
     if (limit < _REGION3_SIZE) {
         limit = _REGION3_SIZE - 1;
         atype = _ASCE_TYPE_SEGMENT;
         etype = _SEGMENT_ENTRY_EMPTY;
     } else if (limit < _REGION2_SIZE) {
         limit = _REGION2_SIZE - 1;
         atype = _ASCE_TYPE_REGION3;
         etype = _REGION3_ENTRY_EMPTY;
     } else if (limit < _REGION1_SIZE) {
         limit = _REGION1_SIZE - 1;
         atype = _ASCE_TYPE_REGION2;
         etype = _REGION2_ENTRY_EMPTY;
     } else {
         limit = -1UL;
         atype = _ASCE_TYPE_REGION1;
         etype = _REGION1_ENTRY_EMPTY;
     }
     gmap = kzalloc(sizeof(struct gmap), GFP_KERNEL_ACCOUNT);
     if (!gmap)
         goto out;
     INIT_LIST_HEAD(&gmap->crst_list);
     INIT_LIST_HEAD(&gmap->children);
     INIT_LIST_HEAD(&gmap->pt_list);
     INIT_RADIX_TREE(&gmap->guest_to_host, GFP_KERNEL_ACCOUNT);
     INIT_RADIX_TREE(&gmap->host_to_guest, GFP_ATOMIC | __GFP_ACCOUNT);
     INIT_RADIX_TREE(&gmap->host_to_rmap, GFP_ATOMIC | __GFP_ACCOUNT);
     spin_lock_init(&gmap->guest_table_lock);
     spin_lock_init(&gmap->shadow_lock);
     refcount_set(&gmap->ref_count, 1);
     page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
     if (!page)
         goto out_free;
     page->index = 0;
     list_add(&page->lru, &gmap->crst_list);
     table = (unsigned long *) page_to_phys(page);
     crst_table_init(table, etype);
     gmap->table = table;
     gmap->asce = atype | _ASCE_TABLE_LENGTH |
         _ASCE_USER_BITS | __pa(table);
     gmap->asce_end = limit;
     return gmap;
 
 out_free:
     kfree(gmap);
 out:
     return NULL;
 }
 
 /**
  * gmap_create - create a guest address space
  * @mm: pointer to the parent mm_struct
  * @limit: maximum size of the gmap address space
  *
  * Returns a guest address space structure.
  */
 struct gmap *gmap_create(struct mm_struct *mm, unsigned long limit)
 {
     struct gmap *gmap;
     unsigned long gmap_asce;
 
     gmap = gmap_alloc(limit);
     if (!gmap)
         return NULL;
     gmap->mm = mm;
     spin_lock(&mm->context.lock);
     list_add_rcu(&gmap->list, &mm->context.gmap_list);
     if (list_is_singular(&mm->context.gmap_list))
         gmap_asce = gmap->asce;
     else
         gmap_asce = -1UL;
     WRITE_ONCE(mm->context.gmap_asce, gmap_asce);
     spin_unlock(&mm->context.lock);
     return gmap;
 }
 EXPORT_SYMBOL_GPL(gmap_create);
 
 static void gmap_flush_tlb(struct gmap *gmap)
 {
     if (MACHINE_HAS_IDTE)
         __tlb_flush_idte(gmap->asce);
     else
         __tlb_flush_global();
 }
 
 static void gmap_radix_tree_free(struct radix_tree_root *root)
 {
     struct radix_tree_iter iter;
     unsigned long indices[16];
     unsigned long index;
     void __rcu **slot;
     int i, nr;
 
     /* A radix tree is freed by deleting all of its entries */
     index = 0;
     do {
         nr = 0;
         radix_tree_for_each_slot(slot, root, &iter, index) {
             indices[nr] = iter.index;
             if (++nr == 16)
                 break;
         }
         for (i = 0; i < nr; i++) {
             index = indices[i];
             radix_tree_delete(root, index);
         }
     } while (nr > 0);
 }
 
 static void gmap_rmap_radix_tree_free(struct radix_tree_root *root)
 {
     struct gmap_rmap *rmap, *rnext, *head;
     struct radix_tree_iter iter;
     unsigned long indices[16];
     unsigned long index;
     void __rcu **slot;
     int i, nr;
 
     /* A radix tree is freed by deleting all of its entries */
     index = 0;
     do {
         nr = 0;
         radix_tree_for_each_slot(slot, root, &iter, index) {
             indices[nr] = iter.index;
             if (++nr == 16)
                 break;
         }
         for (i = 0; i < nr; i++) {
             index = indices[i];
             head = radix_tree_delete(root, index);
             gmap_for_each_rmap_safe(rmap, rnext, head)
                 kfree(rmap);
         }
     } while (nr > 0);
 }
 
 /**
  * gmap_free - free a guest address space
  * @gmap: pointer to the guest address space structure
  *
  * No locks required. There are no references to this gmap anymore.
  */
 static void gmap_free(struct gmap *gmap)
 {
     struct page *page, *next;
 
     /* Flush tlb of all gmaps (if not already done for shadows) */
     if (!(gmap_is_shadow(gmap) && gmap->removed))
         gmap_flush_tlb(gmap);
     /* Free all segment & region tables. */
     list_for_each_entry_safe(page, next, &gmap->crst_list, lru)
         __free_pages(page, CRST_ALLOC_ORDER);
     gmap_radix_tree_free(&gmap->guest_to_host);
     gmap_radix_tree_free(&gmap->host_to_guest);
 
     /* Free additional data for a shadow gmap */
     if (gmap_is_shadow(gmap)) {
         /* Free all page tables. */
         list_for_each_entry_safe(page, next, &gmap->pt_list, lru)
             page_table_free_pgste(page);
         gmap_rmap_radix_tree_free(&gmap->host_to_rmap);
         /* Release reference to the parent */
         gmap_put(gmap->parent);
     }
 
     kfree(gmap);
 }
 
 /**
  * gmap_get - increase reference counter for guest address space
  * @gmap: pointer to the guest address space structure
  *
  * Returns the gmap pointer
  */
 struct gmap *gmap_get(struct gmap *gmap)
 {
     refcount_inc(&gmap->ref_count);
     return gmap;
 }
 EXPORT_SYMBOL_GPL(gmap_get);
 
 /**
  * gmap_put - decrease reference counter for guest address space
  * @gmap: pointer to the guest address space structure
  *
  * If the reference counter reaches zero the guest address space is freed.
  */
 void gmap_put(struct gmap *gmap)
 {
     if (refcount_dec_and_test(&gmap->ref_count))
         gmap_free(gmap);
 }
 EXPORT_SYMBOL_GPL(gmap_put);
 
 /**
  * gmap_remove - remove a guest address space but do not free it yet
  * @gmap: pointer to the guest address space structure
  */
 void gmap_remove(struct gmap *gmap)
 {
     struct gmap *sg, *next;
     unsigned long gmap_asce;
 
     /* Remove all shadow gmaps linked to this gmap */
     if (!list_empty(&gmap->children)) {
         spin_lock(&gmap->shadow_lock);
         list_for_each_entry_safe(sg, next, &gmap->children, list) {
             list_del(&sg->list);
             gmap_put(sg);
         }
         spin_unlock(&gmap->shadow_lock);
     }
     /* Remove gmap from the pre-mm list */
     spin_lock(&gmap->mm->context.lock);
     list_del_rcu(&gmap->list);
     if (list_empty(&gmap->mm->context.gmap_list))
         gmap_asce = 0;
     else if (list_is_singular(&gmap->mm->context.gmap_list))
         gmap_asce = list_first_entry(&gmap->mm->context.gmap_list,
                          struct gmap, list)->asce;
     else
         gmap_asce = -1UL;
     WRITE_ONCE(gmap->mm->context.gmap_asce, gmap_asce);
     spin_unlock(&gmap->mm->context.lock);
     synchronize_rcu();
     /* Put reference */
     gmap_put(gmap);
 }
 EXPORT_SYMBOL_GPL(gmap_remove);
 
 /**
  * gmap_enable - switch primary space to the guest address space
  * @gmap: pointer to the guest address space structure
  */
 void gmap_enable(struct gmap *gmap)
 {
     S390_lowcore.gmap = (unsigned long) gmap;
 }
 EXPORT_SYMBOL_GPL(gmap_enable);
 
 /**
  * gmap_disable - switch back to the standard primary address space
  * @gmap: pointer to the guest address space structure
  */
 void gmap_disable(struct gmap *gmap)
 {
     S390_lowcore.gmap = 0UL;
 }
 EXPORT_SYMBOL_GPL(gmap_disable);
 
 /**
  * gmap_get_enabled - get a pointer to the currently enabled gmap
  *
  * Returns a pointer to the currently enabled gmap. 0 if none is enabled.
  */
 struct gmap *gmap_get_enabled(void)
 {
     return (struct gmap *) S390_lowcore.gmap;
 }
 EXPORT_SYMBOL_GPL(gmap_get_enabled);
 
 /*
  * gmap_alloc_table is assumed to be called with mmap_lock held
  */
 static int gmap_alloc_table(struct gmap *gmap, unsigned long *table,
                 unsigned long init, unsigned long gaddr)
 {
     struct page *page;
     unsigned long *new;
 
     /* since we dont free the gmap table until gmap_free we can unlock */
     page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
     if (!page)
         return -ENOMEM;
     new = (unsigned long *) page_to_phys(page);
     crst_table_init(new, init);
     spin_lock(&gmap->guest_table_lock);
     if (*table & _REGION_ENTRY_INVALID) {
         list_add(&page->lru, &gmap->crst_list);
         *table = (unsigned long) new | _REGION_ENTRY_LENGTH |
             (*table & _REGION_ENTRY_TYPE_MASK);
         page->index = gaddr;
         page = NULL;
     }
     spin_unlock(&gmap->guest_table_lock);
     if (page)
         __free_pages(page, CRST_ALLOC_ORDER);
     return 0;
 }
 
 /**
  * __gmap_segment_gaddr - find virtual address from segment pointer
  * @entry: pointer to a segment table entry in the guest address space
  *
  * Returns the virtual address in the guest address space for the segment
  */
 static unsigned long __gmap_segment_gaddr(unsigned long *entry)
 {
     struct page *page;
     unsigned long offset, mask;
 
     offset = (unsigned long) entry / sizeof(unsigned long);
     offset = (offset & (PTRS_PER_PMD - 1)) * PMD_SIZE;
     mask = ~(PTRS_PER_PMD * sizeof(pmd_t) - 1);
     page = virt_to_page((void *)((unsigned long) entry & mask));
     return page->index + offset;
 }
 
 /**
  * __gmap_unlink_by_vmaddr - unlink a single segment via a host address
  * @gmap: pointer to the guest address space structure
  * @vmaddr: address in the host process address space
  *
  * Returns 1 if a TLB flush is required
  */
 static int __gmap_unlink_by_vmaddr(struct gmap *gmap, unsigned long vmaddr)
 {
     unsigned long *entry;
     int flush = 0;
 
     BUG_ON(gmap_is_shadow(gmap));
     spin_lock(&gmap->guest_table_lock);
     entry = radix_tree_delete(&gmap->host_to_guest, vmaddr >> PMD_SHIFT);
     if (entry) {
         flush = (*entry != _SEGMENT_ENTRY_EMPTY);
         *entry = _SEGMENT_ENTRY_EMPTY;
     }
     spin_unlock(&gmap->guest_table_lock);
     return flush;
 }
 
 /**
  * __gmap_unmap_by_gaddr - unmap a single segment via a guest address
  * @gmap: pointer to the guest address space structure
  * @gaddr: address in the guest address space
  *
  * Returns 1 if a TLB flush is required
  */
 static int __gmap_unmap_by_gaddr(struct gmap *gmap, unsigned long gaddr)
 {
     unsigned long vmaddr;
 
     vmaddr = (unsigned long) radix_tree_delete(&gmap->guest_to_host,
                            gaddr >> PMD_SHIFT);
     return vmaddr ? __gmap_unlink_by_vmaddr(gmap, vmaddr) : 0;
 }
 
 /**
  * gmap_unmap_segment - unmap segment from the guest address space
  * @gmap: pointer to the guest address space structure
  * @to: address in the guest address space
  * @len: length of the memory area to unmap
  *
  * Returns 0 if the unmap succeeded, -EINVAL if not.
  */
 int gmap_unmap_segment(struct gmap *gmap, unsigned long to, unsigned long len)
 {
     unsigned long off;
     int flush;
 
     BUG_ON(gmap_is_shadow(gmap));
     if ((to | len) & (PMD_SIZE - 1))
         return -EINVAL;
     if (len == 0 || to + len < to)
         return -EINVAL;
 
     flush = 0;
     mmap_write_lock(gmap->mm);
     for (off = 0; off < len; off += PMD_SIZE)
         flush |= __gmap_unmap_by_gaddr(gmap, to + off);
     mmap_write_unlock(gmap->mm);
     if (flush)
         gmap_flush_tlb(gmap);
     return 0;
 }
 EXPORT_SYMBOL_GPL(gmap_unmap_segment);
 
 /**
  * gmap_map_segment - map a segment to the guest address space
  * @gmap: pointer to the guest address space structure
  * @from: source address in the parent address space
  * @to: target address in the guest address space
  * @len: length of the memory area to map
  *
  * Returns 0 if the mmap succeeded, -EINVAL or -ENOMEM if not.
  */
 int gmap_map_segment(struct gmap *gmap, unsigned long from,
              unsigned long to, unsigned long len)
 {
     unsigned long off;
     int flush;
 
     BUG_ON(gmap_is_shadow(gmap));
     if ((from | to | len) & (PMD_SIZE - 1))
         return -EINVAL;
     if (len == 0 || from + len < from || to + len < to ||
         from + len - 1 > TASK_SIZE_MAX || to + len - 1 > gmap->asce_end)
         return -EINVAL;
 
     flush = 0;
     mmap_write_lock(gmap->mm);
     for (off = 0; off < len; off += PMD_SIZE) {
         /* Remove old translation */
         flush |= __gmap_unmap_by_gaddr(gmap, to + off);
         /* Store new translation */
         if (radix_tree_insert(&gmap->guest_to_host,
                       (to + off) >> PMD_SHIFT,
                       (void *) from + off))
             break;
     }
     mmap_write_unlock(gmap->mm);
     if (flush)
         gmap_flush_tlb(gmap);
     if (off >= len)
         return 0;
     gmap_unmap_segment(gmap, to, len);
     return -ENOMEM;
 }
 EXPORT_SYMBOL_GPL(gmap_map_segment);
 
 /**
  * __gmap_translate - translate a guest address to a user space address
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: guest address
  *
  * Returns user space address which corresponds to the guest address or
  * -EFAULT if no such mapping exists.
  * This function does not establish potentially missing page table entries.
  * The mmap_lock of the mm that belongs to the address space must be held
  * when this function gets called.
  *
  * Note: Can also be called for shadow gmaps.
  */
 unsigned long __gmap_translate(struct gmap *gmap, unsigned long gaddr)
 {
     unsigned long vmaddr;
 
     vmaddr = (unsigned long)
         radix_tree_lookup(&gmap->guest_to_host, gaddr >> PMD_SHIFT);
     /* Note: guest_to_host is empty for a shadow gmap */
     return vmaddr ? (vmaddr | (gaddr & ~PMD_MASK)) : -EFAULT;
 }
 EXPORT_SYMBOL_GPL(__gmap_translate);
 
 /**
  * gmap_translate - translate a guest address to a user space address
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: guest address
  *
  * Returns user space address which corresponds to the guest address or
  * -EFAULT if no such mapping exists.
  * This function does not establish potentially missing page table entries.
  */
 unsigned long gmap_translate(struct gmap *gmap, unsigned long gaddr)
 {
     unsigned long rc;
 
     mmap_read_lock(gmap->mm);
     rc = __gmap_translate(gmap, gaddr);
     mmap_read_unlock(gmap->mm);
     return rc;
 }
 EXPORT_SYMBOL_GPL(gmap_translate);
 
 /**
  * gmap_unlink - disconnect a page table from the gmap shadow tables
  * @mm: pointer to the parent mm_struct
  * @table: pointer to the host page table
  * @vmaddr: vm address associated with the host page table
  */
 void gmap_unlink(struct mm_struct *mm, unsigned long *table,
          unsigned long vmaddr)
 {
     struct gmap *gmap;
     int flush;
 
     rcu_read_lock();
     list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
         flush = __gmap_unlink_by_vmaddr(gmap, vmaddr);
         if (flush)
             gmap_flush_tlb(gmap);
     }
     rcu_read_unlock();
 }
 
 static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *old, pmd_t new,
                unsigned long gaddr);
 
 /**
  * __gmap_link - set up shadow page tables to connect a host to a guest address
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: guest address
  * @vmaddr: vm address
  *
  * Returns 0 on success, -ENOMEM for out of memory conditions, and -EFAULT
  * if the vm address is already mapped to a different guest segment.
  * The mmap_lock of the mm that belongs to the address space must be held
  * when this function gets called.
  */
 int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
 {
     struct mm_struct *mm;
     unsigned long *table;
     spinlock_t *ptl;
     pgd_t *pgd;
     p4d_t *p4d;
     pud_t *pud;
     pmd_t *pmd;
     u64 unprot;
     int rc;
 
     BUG_ON(gmap_is_shadow(gmap));
     /* Create higher level tables in the gmap page table */
     table = gmap->table;
     if ((gmap->asce & _ASCE_TYPE_MASK) >= _ASCE_TYPE_REGION1) {
         table += (gaddr & _REGION1_INDEX) >> _REGION1_SHIFT;
         if ((*table & _REGION_ENTRY_INVALID) &&
             gmap_alloc_table(gmap, table, _REGION2_ENTRY_EMPTY,
                      gaddr & _REGION1_MASK))
             return -ENOMEM;
         table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
     }
     if ((gmap->asce & _ASCE_TYPE_MASK) >= _ASCE_TYPE_REGION2) {
         table += (gaddr & _REGION2_INDEX) >> _REGION2_SHIFT;
         if ((*table & _REGION_ENTRY_INVALID) &&
             gmap_alloc_table(gmap, table, _REGION3_ENTRY_EMPTY,
                      gaddr & _REGION2_MASK))
             return -ENOMEM;
         table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
     }
     if ((gmap->asce & _ASCE_TYPE_MASK) >= _ASCE_TYPE_REGION3) {
         table += (gaddr & _REGION3_INDEX) >> _REGION3_SHIFT;
         if ((*table & _REGION_ENTRY_INVALID) &&
             gmap_alloc_table(gmap, table, _SEGMENT_ENTRY_EMPTY,
                      gaddr & _REGION3_MASK))
             return -ENOMEM;
         table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
     }
     table += (gaddr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
     /* Walk the parent mm page table */
     mm = gmap->mm;
     pgd = pgd_offset(mm, vmaddr);
     VM_BUG_ON(pgd_none(*pgd));
     p4d = p4d_offset(pgd, vmaddr);
     VM_BUG_ON(p4d_none(*p4d));
     pud = pud_offset(p4d, vmaddr);
     VM_BUG_ON(pud_none(*pud));
     /* large puds cannot yet be handled */
     if (pud_large(*pud))
         return -EFAULT;
     pmd = pmd_offset(pud, vmaddr);
     VM_BUG_ON(pmd_none(*pmd));
     /* Are we allowed to use huge pages? */
     if (pmd_large(*pmd) && !gmap->mm->context.allow_gmap_hpage_1m)
         return -EFAULT;
     /* Link gmap segment table entry location to page table. */
     rc = radix_tree_preload(GFP_KERNEL_ACCOUNT);
     if (rc)
         return rc;
     ptl = pmd_lock(mm, pmd);
     spin_lock(&gmap->guest_table_lock);
     if (*table == _SEGMENT_ENTRY_EMPTY) {
         rc = radix_tree_insert(&gmap->host_to_guest,
                        vmaddr >> PMD_SHIFT, table);
         if (!rc) {
             if (pmd_large(*pmd)) {
                 *table = (pmd_val(*pmd) &
                       _SEGMENT_ENTRY_HARDWARE_BITS_LARGE)
                     | _SEGMENT_ENTRY_GMAP_UC;
             } else
                 *table = pmd_val(*pmd) &
                     _SEGMENT_ENTRY_HARDWARE_BITS;
         }
     } else if (*table & _SEGMENT_ENTRY_PROTECT &&
            !(pmd_val(*pmd) & _SEGMENT_ENTRY_PROTECT)) {
         unprot = (u64)*table;
         unprot &= ~_SEGMENT_ENTRY_PROTECT;
         unprot |= _SEGMENT_ENTRY_GMAP_UC;
         gmap_pmdp_xchg(gmap, (pmd_t *)table, __pmd(unprot), gaddr);
     }
     spin_unlock(&gmap->guest_table_lock);
     spin_unlock(ptl);
     radix_tree_preload_end();
     return rc;
 }
 
 /**
  * gmap_fault - resolve a fault on a guest address
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: guest address
  * @fault_flags: flags to pass down to handle_mm_fault()
  *
  * Returns 0 on success, -ENOMEM for out of memory conditions, and -EFAULT
  * if the vm address is already mapped to a different guest segment.
  */
 int gmap_fault(struct gmap *gmap, unsigned long gaddr,
            unsigned int fault_flags)
 {
     unsigned long vmaddr;
     int rc;
     bool unlocked;
 
     mmap_read_lock(gmap->mm);
 
 retry:
     unlocked = false;
     vmaddr = __gmap_translate(gmap, gaddr);
     if (IS_ERR_VALUE(vmaddr)) {
         rc = vmaddr;
         goto out_up;
     }
     if (fixup_user_fault(gmap->mm, vmaddr, fault_flags,
                  &unlocked)) {
         rc = -EFAULT;
         goto out_up;
     }
     /*
      * In the case that fixup_user_fault unlocked the mmap_lock during
      * faultin redo __gmap_translate to not race with a map/unmap_segment.
      */
     if (unlocked)
         goto retry;
 
     rc = __gmap_link(gmap, gaddr, vmaddr);
 out_up:
     mmap_read_unlock(gmap->mm);
     return rc;
 }
 EXPORT_SYMBOL_GPL(gmap_fault);
 
 /*
  * this function is assumed to be called with mmap_lock held
  */
 void __gmap_zap(struct gmap *gmap, unsigned long gaddr)
 {
     struct vm_area_struct *vma;
     unsigned long vmaddr;
     spinlock_t *ptl;
     pte_t *ptep;
 
     /* Find the vm address for the guest address */
     vmaddr = (unsigned long) radix_tree_lookup(&gmap->guest_to_host,
                            gaddr >> PMD_SHIFT);
     if (vmaddr) {
         vmaddr |= gaddr & ~PMD_MASK;
 
         vma = vma_lookup(gmap->mm, vmaddr);
         if (!vma || is_vm_hugetlb_page(vma))
             return;
 
         /* Get pointer to the page table entry */
         ptep = get_locked_pte(gmap->mm, vmaddr, &ptl);
         if (likely(ptep)) {
             ptep_zap_unused(gmap->mm, vmaddr, ptep, 0);
             pte_unmap_unlock(ptep, ptl);
         }
     }
 }
 EXPORT_SYMBOL_GPL(__gmap_zap);
 
 void gmap_discard(struct gmap *gmap, unsigned long from, unsigned long to)
 {
     unsigned long gaddr, vmaddr, size;
     struct vm_area_struct *vma;
 
     mmap_read_lock(gmap->mm);
     for (gaddr = from; gaddr < to;
          gaddr = (gaddr + PMD_SIZE) & PMD_MASK) {
         /* Find the vm address for the guest address */
         vmaddr = (unsigned long)
             radix_tree_lookup(&gmap->guest_to_host,
                       gaddr >> PMD_SHIFT);
         if (!vmaddr)
             continue;
         vmaddr |= gaddr & ~PMD_MASK;
         /* Find vma in the parent mm */
         vma = find_vma(gmap->mm, vmaddr);
         if (!vma)
             continue;
         /*
          * We do not discard pages that are backed by
          * hugetlbfs, so we don't have to refault them.
          */
         if (is_vm_hugetlb_page(vma))
             continue;
         size = min(to - gaddr, PMD_SIZE - (gaddr & ~PMD_MASK));
         zap_page_range(vma, vmaddr, size);
     }
     mmap_read_unlock(gmap->mm);
 }
 EXPORT_SYMBOL_GPL(gmap_discard);
 
 static LIST_HEAD(gmap_notifier_list);
 static DEFINE_SPINLOCK(gmap_notifier_lock);
 
 /**
  * gmap_register_pte_notifier - register a pte invalidation callback
  * @nb: pointer to the gmap notifier block
  */
 void gmap_register_pte_notifier(struct gmap_notifier *nb)
 {
     spin_lock(&gmap_notifier_lock);
     list_add_rcu(&nb->list, &gmap_notifier_list);
     spin_unlock(&gmap_notifier_lock);
 }
 EXPORT_SYMBOL_GPL(gmap_register_pte_notifier);
 
 /**
  * gmap_unregister_pte_notifier - remove a pte invalidation callback
  * @nb: pointer to the gmap notifier block
  */
 void gmap_unregister_pte_notifier(struct gmap_notifier *nb)
 {
     spin_lock(&gmap_notifier_lock);
     list_del_rcu(&nb->list);
     spin_unlock(&gmap_notifier_lock);
     synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(gmap_unregister_pte_notifier);
 
 /**
  * gmap_call_notifier - call all registered invalidation callbacks
  * @gmap: pointer to guest mapping meta data structure
  * @start: start virtual address in the guest address space
  * @end: end virtual address in the guest address space
  */
 static void gmap_call_notifier(struct gmap *gmap, unsigned long start,
                    unsigned long end)
 {
     struct gmap_notifier *nb;
 
     list_for_each_entry(nb, &gmap_notifier_list, list)
         nb->notifier_call(gmap, start, end);
 }
 
 /**
  * gmap_table_walk - walk the gmap page tables
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: virtual address in the guest address space
  * @level: page table level to stop at
  *
  * Returns a table entry pointer for the given guest address and @level
  * @level=0 : returns a pointer to a page table table entry (or NULL)
  * @level=1 : returns a pointer to a segment table entry (or NULL)
  * @level=2 : returns a pointer to a region-3 table entry (or NULL)
  * @level=3 : returns a pointer to a region-2 table entry (or NULL)
  * @level=4 : returns a pointer to a region-1 table entry (or NULL)
  *
  * Returns NULL if the gmap page tables could not be walked to the
  * requested level.
  *
  * Note: Can also be called for shadow gmaps.
  */
 static inline unsigned long *gmap_table_walk(struct gmap *gmap,
                          unsigned long gaddr, int level)
 {
     const int asce_type = gmap->asce & _ASCE_TYPE_MASK;
     unsigned long *table = gmap->table;
 
     if (gmap_is_shadow(gmap) && gmap->removed)
         return NULL;
 
     if (WARN_ON_ONCE(level > (asce_type >> 2) + 1))
         return NULL;
 
     if (asce_type != _ASCE_TYPE_REGION1 &&
         gaddr & (-1UL << (31 + (asce_type >> 2) * 11)))
         return NULL;
 
     switch (asce_type) {
     case _ASCE_TYPE_REGION1:
         table += (gaddr & _REGION1_INDEX) >> _REGION1_SHIFT;
         if (level == 4)
             break;
         if (*table & _REGION_ENTRY_INVALID)
             return NULL;
         table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
         fallthrough;
     case _ASCE_TYPE_REGION2:
         table += (gaddr & _REGION2_INDEX) >> _REGION2_SHIFT;
         if (level == 3)
             break;
         if (*table & _REGION_ENTRY_INVALID)
             return NULL;
         table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
         fallthrough;
     case _ASCE_TYPE_REGION3:
         table += (gaddr & _REGION3_INDEX) >> _REGION3_SHIFT;
         if (level == 2)
             break;
         if (*table & _REGION_ENTRY_INVALID)
             return NULL;
         table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
         fallthrough;
     case _ASCE_TYPE_SEGMENT:
         table += (gaddr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
         if (level == 1)
             break;
         if (*table & _REGION_ENTRY_INVALID)
             return NULL;
         table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
         table += (gaddr & _PAGE_INDEX) >> _PAGE_SHIFT;
     }
     return table;
 }
 
 /**
  * gmap_pte_op_walk - walk the gmap page table, get the page table lock
  *            and return the pte pointer
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: virtual address in the guest address space
  * @ptl: pointer to the spinlock pointer
  *
  * Returns a pointer to the locked pte for a guest address, or NULL
  */
 static pte_t *gmap_pte_op_walk(struct gmap *gmap, unsigned long gaddr,
                    spinlock_t **ptl)
 {
     unsigned long *table;
 
     BUG_ON(gmap_is_shadow(gmap));
     /* Walk the gmap page table, lock and get pte pointer */
     table = gmap_table_walk(gmap, gaddr, 1); /* get segment pointer */
     if (!table || *table & _SEGMENT_ENTRY_INVALID)
         return NULL;
     return pte_alloc_map_lock(gmap->mm, (pmd_t *) table, gaddr, ptl);
 }
 
 /**
  * gmap_pte_op_fixup - force a page in and connect the gmap page table
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: virtual address in the guest address space
  * @vmaddr: address in the host process address space
  * @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
  *
  * Returns 0 if the caller can retry __gmap_translate (might fail again),
  * -ENOMEM if out of memory and -EFAULT if anything goes wrong while fixing
  * up or connecting the gmap page table.
  */
 static int gmap_pte_op_fixup(struct gmap *gmap, unsigned long gaddr,
                  unsigned long vmaddr, int prot)
 {
     struct mm_struct *mm = gmap->mm;
     unsigned int fault_flags;
     bool unlocked = false;
 
     BUG_ON(gmap_is_shadow(gmap));
     fault_flags = (prot == PROT_WRITE) ? FAULT_FLAG_WRITE : 0;
     if (fixup_user_fault(mm, vmaddr, fault_flags, &unlocked))
         return -EFAULT;
     if (unlocked)
         /* lost mmap_lock, caller has to retry __gmap_translate */
         return 0;
     /* Connect the page tables */
     return __gmap_link(gmap, gaddr, vmaddr);
 }
 
 /**
  * gmap_pte_op_end - release the page table lock
  * @ptl: pointer to the spinlock pointer
  */
 static void gmap_pte_op_end(spinlock_t *ptl)
 {
     if (ptl)
         spin_unlock(ptl);
 }
 
 /**
  * gmap_pmd_op_walk - walk the gmap tables, get the guest table lock
  *            and return the pmd pointer
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: virtual address in the guest address space
  *
  * Returns a pointer to the pmd for a guest address, or NULL
  */
 static inline pmd_t *gmap_pmd_op_walk(struct gmap *gmap, unsigned long gaddr)
 {
     pmd_t *pmdp;
 
     BUG_ON(gmap_is_shadow(gmap));
     pmdp = (pmd_t *) gmap_table_walk(gmap, gaddr, 1);
     if (!pmdp)
         return NULL;
 
     /* without huge pages, there is no need to take the table lock */
     if (!gmap->mm->context.allow_gmap_hpage_1m)
         return pmd_none(*pmdp) ? NULL : pmdp;
 
     spin_lock(&gmap->guest_table_lock);
     if (pmd_none(*pmdp)) {
         spin_unlock(&gmap->guest_table_lock);
         return NULL;
     }
 
     /* 4k page table entries are locked via the pte (pte_alloc_map_lock). */
     if (!pmd_large(*pmdp))
         spin_unlock(&gmap->guest_table_lock);
     return pmdp;
 }
 
 /**
  * gmap_pmd_op_end - release the guest_table_lock if needed
  * @gmap: pointer to the guest mapping meta data structure
  * @pmdp: pointer to the pmd
  */
 static inline void gmap_pmd_op_end(struct gmap *gmap, pmd_t *pmdp)
 {
     if (pmd_large(*pmdp))
         spin_unlock(&gmap->guest_table_lock);
 }
 
 /*
  * gmap_protect_pmd - remove access rights to memory and set pmd notification bits
  * @pmdp: pointer to the pmd to be protected
  * @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
  * @bits: notification bits to set
  *
  * Returns:
  * 0 if successfully protected
  * -EAGAIN if a fixup is needed
  * -EINVAL if unsupported notifier bits have been specified
  *
  * Expected to be called with sg->mm->mmap_lock in read and
  * guest_table_lock held.
  */
 static int gmap_protect_pmd(struct gmap *gmap, unsigned long gaddr,
                 pmd_t *pmdp, int prot, unsigned long bits)
 {
     int pmd_i = pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID;
     int pmd_p = pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT;
     pmd_t new = *pmdp;
 
     /* Fixup needed */
     if ((pmd_i && (prot != PROT_NONE)) || (pmd_p && (prot == PROT_WRITE)))
         return -EAGAIN;
 
     if (prot == PROT_NONE && !pmd_i) {
         new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_INVALID));
         gmap_pmdp_xchg(gmap, pmdp, new, gaddr);
     }
 
     if (prot == PROT_READ && !pmd_p) {
         new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_INVALID));
         new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_PROTECT));
         gmap_pmdp_xchg(gmap, pmdp, new, gaddr);
     }
 
     if (bits & GMAP_NOTIFY_MPROT)
         set_pmd(pmdp, set_pmd_bit(*pmdp, __pgprot(_SEGMENT_ENTRY_GMAP_IN)));
 
     /* Shadow GMAP protection needs split PMDs */
     if (bits & GMAP_NOTIFY_SHADOW)
         return -EINVAL;
 
     return 0;
 }
 
 /*
  * gmap_protect_pte - remove access rights to memory and set pgste bits
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: virtual address in the guest address space
  * @pmdp: pointer to the pmd associated with the pte
  * @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
  * @bits: notification bits to set
  *
  * Returns 0 if successfully protected, -ENOMEM if out of memory and
  * -EAGAIN if a fixup is needed.
  *
  * Expected to be called with sg->mm->mmap_lock in read
  */
 static int gmap_protect_pte(struct gmap *gmap, unsigned long gaddr,
                 pmd_t *pmdp, int prot, unsigned long bits)
 {
     int rc;
     pte_t *ptep;
     spinlock_t *ptl = NULL;
     unsigned long pbits = 0;
 
     if (pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)
         return -EAGAIN;
 
     ptep = pte_alloc_map_lock(gmap->mm, pmdp, gaddr, &ptl);
     if (!ptep)
         return -ENOMEM;
 
     pbits |= (bits & GMAP_NOTIFY_MPROT) ? PGSTE_IN_BIT : 0;
     pbits |= (bits & GMAP_NOTIFY_SHADOW) ? PGSTE_VSIE_BIT : 0;
     /* Protect and unlock. */
     rc = ptep_force_prot(gmap->mm, gaddr, ptep, prot, pbits);
     gmap_pte_op_end(ptl);
     return rc;
 }
 
 /*
  * gmap_protect_range - remove access rights to memory and set pgste bits
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: virtual address in the guest address space
  * @len: size of area
  * @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
  * @bits: pgste notification bits to set
  *
  * Returns 0 if successfully protected, -ENOMEM if out of memory and
  * -EFAULT if gaddr is invalid (or mapping for shadows is missing).
  *
  * Called with sg->mm->mmap_lock in read.
  */
 static int gmap_protect_range(struct gmap *gmap, unsigned long gaddr,
                   unsigned long len, int prot, unsigned long bits)
 {
     unsigned long vmaddr, dist;
     pmd_t *pmdp;
     int rc;
 
     BUG_ON(gmap_is_shadow(gmap));
     while (len) {
         rc = -EAGAIN;
         pmdp = gmap_pmd_op_walk(gmap, gaddr);
         if (pmdp) {
             if (!pmd_large(*pmdp)) {
                 rc = gmap_protect_pte(gmap, gaddr, pmdp, prot,
                               bits);
                 if (!rc) {
                     len -= PAGE_SIZE;
                     gaddr += PAGE_SIZE;
                 }
             } else {
                 rc = gmap_protect_pmd(gmap, gaddr, pmdp, prot,
                               bits);
                 if (!rc) {
                     dist = HPAGE_SIZE - (gaddr & ~HPAGE_MASK);
                     len = len < dist ? 0 : len - dist;
                     gaddr = (gaddr & HPAGE_MASK) + HPAGE_SIZE;
                 }
             }
             gmap_pmd_op_end(gmap, pmdp);
         }
         if (rc) {
             if (rc == -EINVAL)
                 return rc;
 
             /* -EAGAIN, fixup of userspace mm and gmap */
             vmaddr = __gmap_translate(gmap, gaddr);
             if (IS_ERR_VALUE(vmaddr))
                 return vmaddr;
             rc = gmap_pte_op_fixup(gmap, gaddr, vmaddr, prot);
             if (rc)
                 return rc;
         }
     }
     return 0;
 }
 
 /**
  * gmap_mprotect_notify - change access rights for a range of ptes and
  *                        call the notifier if any pte changes again
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: virtual address in the guest address space
  * @len: size of area
  * @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
  *
  * Returns 0 if for each page in the given range a gmap mapping exists,
  * the new access rights could be set and the notifier could be armed.
  * If the gmap mapping is missing for one or more pages -EFAULT is
  * returned. If no memory could be allocated -ENOMEM is returned.
  * This function establishes missing page table entries.
  */
 int gmap_mprotect_notify(struct gmap *gmap, unsigned long gaddr,
              unsigned long len, int prot)
 {
     int rc;
 
     if ((gaddr & ~PAGE_MASK) || (len & ~PAGE_MASK) || gmap_is_shadow(gmap))
         return -EINVAL;
     if (!MACHINE_HAS_ESOP && prot == PROT_READ)
         return -EINVAL;
     mmap_read_lock(gmap->mm);
     rc = gmap_protect_range(gmap, gaddr, len, prot, GMAP_NOTIFY_MPROT);
     mmap_read_unlock(gmap->mm);
     return rc;
 }
 EXPORT_SYMBOL_GPL(gmap_mprotect_notify);
 
 /**
  * gmap_read_table - get an unsigned long value from a guest page table using
  *                   absolute addressing, without marking the page referenced.
  * @gmap: pointer to guest mapping meta data structure
  * @gaddr: virtual address in the guest address space
  * @val: pointer to the unsigned long value to return
  *
  * Returns 0 if the value was read, -ENOMEM if out of memory and -EFAULT
  * if reading using the virtual address failed. -EINVAL if called on a gmap
  * shadow.
  *
  * Called with gmap->mm->mmap_lock in read.
  */
 int gmap_read_table(struct gmap *gmap, unsigned long gaddr, unsigned long *val)
 {
     unsigned long address, vmaddr;
     spinlock_t *ptl;
     pte_t *ptep, pte;
     int rc;
 
     if (gmap_is_shadow(gmap))
         return -EINVAL;
 
     while (1) {
         rc = -EAGAIN;
         ptep = gmap_pte_op_walk(gmap, gaddr, &ptl);
         if (ptep) {
             pte = *ptep;
             if (pte_present(pte) && (pte_val(pte) & _PAGE_READ)) {
                 address = pte_val(pte) & PAGE_MASK;
                 address += gaddr & ~PAGE_MASK;
                 *val = *(unsigned long *) address;
                 set_pte(ptep, set_pte_bit(*ptep, __pgprot(_PAGE_YOUNG)));
                 /* Do *NOT* clear the _PAGE_INVALID bit! */
                 rc = 0;
             }
             gmap_pte_op_end(ptl);
         }
         if (!rc)
             break;
         vmaddr = __gmap_translate(gmap, gaddr);
         if (IS_ERR_VALUE(vmaddr)) {
             rc = vmaddr;
             break;
         }
         rc = gmap_pte_op_fixup(gmap, gaddr, vmaddr, PROT_READ);
         if (rc)
             break;
     }
     return rc;
 }
 EXPORT_SYMBOL_GPL(gmap_read_table);
 
 /**
  * gmap_insert_rmap - add a rmap to the host_to_rmap radix tree
  * @sg: pointer to the shadow guest address space structure
  * @vmaddr: vm address associated with the rmap
  * @rmap: pointer to the rmap structure
  *
  * Called with the sg->guest_table_lock
  */
 static inline void gmap_insert_rmap(struct gmap *sg, unsigned long vmaddr,
                     struct gmap_rmap *rmap)
 {
     struct gmap_rmap *temp;
     void __rcu **slot;
 
     BUG_ON(!gmap_is_shadow(sg));
     slot = radix_tree_lookup_slot(&sg->host_to_rmap, vmaddr >> PAGE_SHIFT);
     if (slot) {
         rmap->next = radix_tree_deref_slot_protected(slot,
                             &sg->guest_table_lock);
         for (temp = rmap->next; temp; temp = temp->next) {
             if (temp->raddr == rmap->raddr) {
                 kfree(rmap);
                 return;
             }
         }
         radix_tree_replace_slot(&sg->host_to_rmap, slot, rmap);
     } else {
         rmap->next = NULL;
         radix_tree_insert(&sg->host_to_rmap, vmaddr >> PAGE_SHIFT,
                   rmap);
     }
 }
 
 /**
  * gmap_protect_rmap - restrict access rights to memory (RO) and create an rmap
  * @sg: pointer to the shadow guest address space structure
  * @raddr: rmap address in the shadow gmap
  * @paddr: address in the parent guest address space
  * @len: length of the memory area to protect
  *
  * Returns 0 if successfully protected and the rmap was created, -ENOMEM
  * if out of memory and -EFAULT if paddr is invalid.
  */
 static int gmap_protect_rmap(struct gmap *sg, unsigned long raddr,
                  unsigned long paddr, unsigned long len)
 {
     struct gmap *parent;
     struct gmap_rmap *rmap;
     unsigned long vmaddr;
     spinlock_t *ptl;
     pte_t *ptep;
     int rc;
 
     BUG_ON(!gmap_is_shadow(sg));
     parent = sg->parent;
     while (len) {
         vmaddr = __gmap_translate(parent, paddr);
         if (IS_ERR_VALUE(vmaddr))
             return vmaddr;
         rmap = kzalloc(sizeof(*rmap), GFP_KERNEL_ACCOUNT);
         if (!rmap)
             return -ENOMEM;
         rmap->raddr = raddr;
         rc = radix_tree_preload(GFP_KERNEL_ACCOUNT);
         if (rc) {
             kfree(rmap);
             return rc;
         }
         rc = -EAGAIN;
         ptep = gmap_pte_op_walk(parent, paddr, &ptl);
         if (ptep) {
             spin_lock(&sg->guest_table_lock);
             rc = ptep_force_prot(parent->mm, paddr, ptep, PROT_READ,
                          PGSTE_VSIE_BIT);
             if (!rc)
                 gmap_insert_rmap(sg, vmaddr, rmap);
             spin_unlock(&sg->guest_table_lock);
             gmap_pte_op_end(ptl);
         }
         radix_tree_preload_end();
         if (rc) {
             kfree(rmap);
             rc = gmap_pte_op_fixup(parent, paddr, vmaddr, PROT_READ);
             if (rc)
                 return rc;
             continue;
         }
         paddr += PAGE_SIZE;
         len -= PAGE_SIZE;
     }
     return 0;
 }
 
 #define _SHADOW_RMAP_MASK   0x7
 #define _SHADOW_RMAP_REGION1    0x5
 #define _SHADOW_RMAP_REGION2    0x4
 #define _SHADOW_RMAP_REGION3    0x3
 #define _SHADOW_RMAP_SEGMENT    0x2
 #define _SHADOW_RMAP_PGTABLE    0x1
 
 /**
  * gmap_idte_one - invalidate a single region or segment table entry
  * @asce: region or segment table *origin* + table-type bits
  * @vaddr: virtual address to identify the table entry to flush
  *
  * The invalid bit of a single region or segment table entry is set
  * and the associated TLB entries depending on the entry are flushed.
  * The table-type of the @asce identifies the portion of the @vaddr
  * that is used as the invalidation index.
  */
 static inline void gmap_idte_one(unsigned long asce, unsigned long vaddr)
 {
     asm volatile(
         "   idte    %0,0,%1"
         : : "a" (asce), "a" (vaddr) : "cc", "memory");
 }
 
 /**
  * gmap_unshadow_page - remove a page from a shadow page table
  * @sg: pointer to the shadow guest address space structure
  * @raddr: rmap address in the shadow guest address space
  *
  * Called with the sg->guest_table_lock
  */
 static void gmap_unshadow_page(struct gmap *sg, unsigned long raddr)
 {
     unsigned long *table;
 
     BUG_ON(!gmap_is_shadow(sg));
     table = gmap_table_walk(sg, raddr, 0); /* get page table pointer */
     if (!table || *table & _PAGE_INVALID)
         return;
     gmap_call_notifier(sg, raddr, raddr + _PAGE_SIZE - 1);
     ptep_unshadow_pte(sg->mm, raddr, (pte_t *) table);
 }
 
 /**
  * __gmap_unshadow_pgt - remove all entries from a shadow page table
  * @sg: pointer to the shadow guest address space structure
  * @raddr: rmap address in the shadow guest address space
  * @pgt: pointer to the start of a shadow page table
  *
  * Called with the sg->guest_table_lock
  */
 static void __gmap_unshadow_pgt(struct gmap *sg, unsigned long raddr,
                 unsigned long *pgt)
 {
     int i;
 
     BUG_ON(!gmap_is_shadow(sg));
     for (i = 0; i < _PAGE_ENTRIES; i++, raddr += _PAGE_SIZE)
         pgt[i] = _PAGE_INVALID;
 }
 
 /**
  * gmap_unshadow_pgt - remove a shadow page table from a segment entry
  * @sg: pointer to the shadow guest address space structure
  * @raddr: address in the shadow guest address space
  *
  * Called with the sg->guest_table_lock
  */
 static void gmap_unshadow_pgt(struct gmap *sg, unsigned long raddr)
 {
     unsigned long sto, *ste, *pgt;
     struct page *page;
 
     BUG_ON(!gmap_is_shadow(sg));
     ste = gmap_table_walk(sg, raddr, 1); /* get segment pointer */
     if (!ste || !(*ste & _SEGMENT_ENTRY_ORIGIN))
         return;
     gmap_call_notifier(sg, raddr, raddr + _SEGMENT_SIZE - 1);
     sto = (unsigned long) (ste - ((raddr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT));
     gmap_idte_one(sto | _ASCE_TYPE_SEGMENT, raddr);
     pgt = (unsigned long *)(*ste & _SEGMENT_ENTRY_ORIGIN);
     *ste = _SEGMENT_ENTRY_EMPTY;
     __gmap_unshadow_pgt(sg, raddr, pgt);
     /* Free page table */
     page = pfn_to_page(__pa(pgt) >> PAGE_SHIFT);
     list_del(&page->lru);
     page_table_free_pgste(page);
 }
 
 /**
  * __gmap_unshadow_sgt - remove all entries from a shadow segment table
  * @sg: pointer to the shadow guest address space structure
  * @raddr: rmap address in the shadow guest address space
  * @sgt: pointer to the start of a shadow segment table
  *
  * Called with the sg->guest_table_lock
  */
 static void __gmap_unshadow_sgt(struct gmap *sg, unsigned long raddr,
                 unsigned long *sgt)
 {
     unsigned long *pgt;
     struct page *page;
     int i;
 
     BUG_ON(!gmap_is_shadow(sg));
     for (i = 0; i < _CRST_ENTRIES; i++, raddr += _SEGMENT_SIZE) {
         if (!(sgt[i] & _SEGMENT_ENTRY_ORIGIN))
             continue;
         pgt = (unsigned long *)(sgt[i] & _REGION_ENTRY_ORIGIN);
         sgt[i] = _SEGMENT_ENTRY_EMPTY;
         __gmap_unshadow_pgt(sg, raddr, pgt);
         /* Free page table */
         page = pfn_to_page(__pa(pgt) >> PAGE_SHIFT);
         list_del(&page->lru);
         page_table_free_pgste(page);
     }
 }
 
 /**
  * gmap_unshadow_sgt - remove a shadow segment table from a region-3 entry
  * @sg: pointer to the shadow guest address space structure
  * @raddr: rmap address in the shadow guest address space
  *
  * Called with the shadow->guest_table_lock
  */
 static void gmap_unshadow_sgt(struct gmap *sg, unsigned long raddr)
 {
     unsigned long r3o, *r3e, *sgt;
     struct page *page;
 
     BUG_ON(!gmap_is_shadow(sg));
     r3e = gmap_table_walk(sg, raddr, 2); /* get region-3 pointer */
     if (!r3e || !(*r3e & _REGION_ENTRY_ORIGIN))
         return;
     gmap_call_notifier(sg, raddr, raddr + _REGION3_SIZE - 1);
     r3o = (unsigned long) (r3e - ((raddr & _REGION3_INDEX) >> _REGION3_SHIFT));
     gmap_idte_one(r3o | _ASCE_TYPE_REGION3, raddr);
     sgt = (unsigned long *)(*r3e & _REGION_ENTRY_ORIGIN);
     *r3e = _REGION3_ENTRY_EMPTY;
     __gmap_unshadow_sgt(sg, raddr, sgt);
     /* Free segment table */
     page = pfn_to_page(__pa(sgt) >> PAGE_SHIFT);
     list_del(&page->lru);
     __free_pages(page, CRST_ALLOC_ORDER);
 }
 
 /**
  * __gmap_unshadow_r3t - remove all entries from a shadow region-3 table
  * @sg: pointer to the shadow guest address space structure
  * @raddr: address in the shadow guest address space
  * @r3t: pointer to the start of a shadow region-3 table
  *
  * Called with the sg->guest_table_lock
  */
 static void __gmap_unshadow_r3t(struct gmap *sg, unsigned long raddr,
                 unsigned long *r3t)
 {
     unsigned long *sgt;
     struct page *page;
     int i;
 
     BUG_ON(!gmap_is_shadow(sg));
     for (i = 0; i < _CRST_ENTRIES; i++, raddr += _REGION3_SIZE) {
         if (!(r3t[i] & _REGION_ENTRY_ORIGIN))
             continue;
         sgt = (unsigned long *)(r3t[i] & _REGION_ENTRY_ORIGIN);
         r3t[i] = _REGION3_ENTRY_EMPTY;
         __gmap_unshadow_sgt(sg, raddr, sgt);
         /* Free segment table */
         page = pfn_to_page(__pa(sgt) >> PAGE_SHIFT);
         list_del(&page->lru);
         __free_pages(page, CRST_ALLOC_ORDER);
     }
 }
 
 /**
  * gmap_unshadow_r3t - remove a shadow region-3 table from a region-2 entry
  * @sg: pointer to the shadow guest address space structure
  * @raddr: rmap address in the shadow guest address space
  *
  * Called with the sg->guest_table_lock
  */
 static void gmap_unshadow_r3t(struct gmap *sg, unsigned long raddr)
 {
     unsigned long r2o, *r2e, *r3t;
     struct page *page;
 
     BUG_ON(!gmap_is_shadow(sg));
     r2e = gmap_table_walk(sg, raddr, 3); /* get region-2 pointer */
     if (!r2e || !(*r2e & _REGION_ENTRY_ORIGIN))
         return;
     gmap_call_notifier(sg, raddr, raddr + _REGION2_SIZE - 1);
     r2o = (unsigned long) (r2e - ((raddr & _REGION2_INDEX) >> _REGION2_SHIFT));
     gmap_idte_one(r2o | _ASCE_TYPE_REGION2, raddr);
     r3t = (unsigned long *)(*r2e & _REGION_ENTRY_ORIGIN);
     *r2e = _REGION2_ENTRY_EMPTY;
     __gmap_unshadow_r3t(sg, raddr, r3t);
     /* Free region 3 table */
     page = pfn_to_page(__pa(r3t) >> PAGE_SHIFT);
     list_del(&page->lru);
     __free_pages(page, CRST_ALLOC_ORDER);
 }
 
 /**
  * __gmap_unshadow_r2t - remove all entries from a shadow region-2 table
  * @sg: pointer to the shadow guest address space structure
  * @raddr: rmap address in the shadow guest address space
  * @r2t: pointer to the start of a shadow region-2 table
  *
  * Called with the sg->guest_table_lock
  */
 static void __gmap_unshadow_r2t(struct gmap *sg, unsigned long raddr,
                 unsigned long *r2t)
 {
     unsigned long *r3t;
     struct page *page;
     int i;
 
     BUG_ON(!gmap_is_shadow(sg));
     for (i = 0; i < _CRST_ENTRIES; i++, raddr += _REGION2_SIZE) {
         if (!(r2t[i] & _REGION_ENTRY_ORIGIN))
             continue;
         r3t = (unsigned long *)(r2t[i] & _REGION_ENTRY_ORIGIN);
         r2t[i] = _REGION2_ENTRY_EMPTY;
         __gmap_unshadow_r3t(sg, raddr, r3t);
         /* Free region 3 table */
         page = pfn_to_page(__pa(r3t) >> PAGE_SHIFT);
         list_del(&page->lru);
         __free_pages(page, CRST_ALLOC_ORDER);
     }
 }
 
 /**
  * gmap_unshadow_r2t - remove a shadow region-2 table from a region-1 entry
  * @sg: pointer to the shadow guest address space structure
  * @raddr: rmap address in the shadow guest address space
  *
  * Called with the sg->guest_table_lock
  */
 static void gmap_unshadow_r2t(struct gmap *sg, unsigned long raddr)
 {
     unsigned long r1o, *r1e, *r2t;
     struct page *page;
 
     BUG_ON(!gmap_is_shadow(sg));
     r1e = gmap_table_walk(sg, raddr, 4); /* get region-1 pointer */
     if (!r1e || !(*r1e & _REGION_ENTRY_ORIGIN))
         return;
     gmap_call_notifier(sg, raddr, raddr + _REGION1_SIZE - 1);
     r1o = (unsigned long) (r1e - ((raddr & _REGION1_INDEX) >> _REGION1_SHIFT));
     gmap_idte_one(r1o | _ASCE_TYPE_REGION1, raddr);
     r2t = (unsigned long *)(*r1e & _REGION_ENTRY_ORIGIN);
     *r1e = _REGION1_ENTRY_EMPTY;
     __gmap_unshadow_r2t(sg, raddr, r2t);
     /* Free region 2 table */
     page = pfn_to_page(__pa(r2t) >> PAGE_SHIFT);
     list_del(&page->lru);
     __free_pages(page, CRST_ALLOC_ORDER);
 }
 
 /**
  * __gmap_unshadow_r1t - remove all entries from a shadow region-1 table
  * @sg: pointer to the shadow guest address space structure
  * @raddr: rmap address in the shadow guest address space
  * @r1t: pointer to the start of a shadow region-1 table
  *
  * Called with the shadow->guest_table_lock
  */
 static void __gmap_unshadow_r1t(struct gmap *sg, unsigned long raddr,
                 unsigned long *r1t)
 {
     unsigned long asce, *r2t;
     struct page *page;
     int i;
 
     BUG_ON(!gmap_is_shadow(sg));
     asce = (unsigned long) r1t | _ASCE_TYPE_REGION1;
     for (i = 0; i < _CRST_ENTRIES; i++, raddr += _REGION1_SIZE) {
         if (!(r1t[i] & _REGION_ENTRY_ORIGIN))
             continue;
         r2t = (unsigned long *)(r1t[i] & _REGION_ENTRY_ORIGIN);
         __gmap_unshadow_r2t(sg, raddr, r2t);
         /* Clear entry and flush translation r1t -> r2t */
         gmap_idte_one(asce, raddr);
         r1t[i] = _REGION1_ENTRY_EMPTY;
         /* Free region 2 table */
         page = pfn_to_page(__pa(r2t) >> PAGE_SHIFT);
         list_del(&page->lru);
         __free_pages(page, CRST_ALLOC_ORDER);
     }
 }
 
 /**
  * gmap_unshadow - remove a shadow page table completely
  * @sg: pointer to the shadow guest address space structure
  *
  * Called with sg->guest_table_lock
  */
 static void gmap_unshadow(struct gmap *sg)
 {
     unsigned long *table;
 
     BUG_ON(!gmap_is_shadow(sg));
     if (sg->removed)
         return;
     sg->removed = 1;
     gmap_call_notifier(sg, 0, -1UL);
     gmap_flush_tlb(sg);
     table = (unsigned long *)(sg->asce & _ASCE_ORIGIN);
     switch (sg->asce & _ASCE_TYPE_MASK) {
     case _ASCE_TYPE_REGION1:
         __gmap_unshadow_r1t(sg, 0, table);
         break;
     case _ASCE_TYPE_REGION2:
         __gmap_unshadow_r2t(sg, 0, table);
         break;
     case _ASCE_TYPE_REGION3:
         __gmap_unshadow_r3t(sg, 0, table);
         break;
     case _ASCE_TYPE_SEGMENT:
         __gmap_unshadow_sgt(sg, 0, table);
         break;
     }
 }
 
 /**
  * gmap_find_shadow - find a specific asce in the list of shadow tables
  * @parent: pointer to the parent gmap
  * @asce: ASCE for which the shadow table is created
  * @edat_level: edat level to be used for the shadow translation
  *
  * Returns the pointer to a gmap if a shadow table with the given asce is
  * already available, ERR_PTR(-EAGAIN) if another one is just being created,
  * otherwise NULL
  */
 static struct gmap *gmap_find_shadow(struct gmap *parent, unsigned long asce,
                      int edat_level)
 {
     struct gmap *sg;
 
     list_for_each_entry(sg, &parent->children, list) {
         if (sg->orig_asce != asce || sg->edat_level != edat_level ||
             sg->removed)
             continue;
         if (!sg->initialized)
             return ERR_PTR(-EAGAIN);
         refcount_inc(&sg->ref_count);
         return sg;
     }
     return NULL;
 }
 
 /**
  * gmap_shadow_valid - check if a shadow guest address space matches the
  *                     given properties and is still valid
  * @sg: pointer to the shadow guest address space structure
  * @asce: ASCE for which the shadow table is requested
  * @edat_level: edat level to be used for the shadow translation
  *
  * Returns 1 if the gmap shadow is still valid and matches the given
  * properties, the caller can continue using it. Returns 0 otherwise, the
  * caller has to request a new shadow gmap in this case.
  *
  */
 int gmap_shadow_valid(struct gmap *sg, unsigned long asce, int edat_level)
 {
     if (sg->removed)
         return 0;
     return sg->orig_asce == asce && sg->edat_level == edat_level;
 }
 EXPORT_SYMBOL_GPL(gmap_shadow_valid);
 
 /**
  * gmap_shadow - create/find a shadow guest address space
  * @parent: pointer to the parent gmap
  * @asce: ASCE for which the shadow table is created
  * @edat_level: edat level to be used for the shadow translation
  *
  * The pages of the top level page table referred by the asce parameter
  * will be set to read-only and marked in the PGSTEs of the kvm process.
  * The shadow table will be removed automatically on any change to the
  * PTE mapping for the source table.
  *
  * Returns a guest address space structure, ERR_PTR(-ENOMEM) if out of memory,
  * ERR_PTR(-EAGAIN) if the caller has to retry and ERR_PTR(-EFAULT) if the
  * parent gmap table could not be protected.
  */
 struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce,
              int edat_level)
 {
     struct gmap *sg, *new;
     unsigned long limit;
     int rc;
 
     BUG_ON(parent->mm->context.allow_gmap_hpage_1m);
     BUG_ON(gmap_is_shadow(parent));
     spin_lock(&parent->shadow_lock);
     sg = gmap_find_shadow(parent, asce, edat_level);
     spin_unlock(&parent->shadow_lock);
     if (sg)
         return sg;
     /* Create a new shadow gmap */
     limit = -1UL >> (33 - (((asce & _ASCE_TYPE_MASK) >> 2) * 11));
     if (asce & _ASCE_REAL_SPACE)
         limit = -1UL;
     new = gmap_alloc(limit);
     if (!new)
         return ERR_PTR(-ENOMEM);
     new->mm = parent->mm;
     new->parent = gmap_get(parent);
     new->orig_asce = asce;
     new->edat_level = edat_level;
     new->initialized = false;
     spin_lock(&parent->shadow_lock);
     /* Recheck if another CPU created the same shadow */
     sg = gmap_find_shadow(parent, asce, edat_level);
     if (sg) {
         spin_unlock(&parent->shadow_lock);
         gmap_free(new);
         return sg;
     }
     if (asce & _ASCE_REAL_SPACE) {
         /* only allow one real-space gmap shadow */
         list_for_each_entry(sg, &parent->children, list) {
             if (sg->orig_asce & _ASCE_REAL_SPACE) {
                 spin_lock(&sg->guest_table_lock);
                 gmap_unshadow(sg);
                 spin_unlock(&sg->guest_table_lock);
                 list_del(&sg->list);
                 gmap_put(sg);
                 break;
             }
         }
     }
     refcount_set(&new->ref_count, 2);
     list_add(&new->list, &parent->children);
     if (asce & _ASCE_REAL_SPACE) {
         /* nothing to protect, return right away */
         new->initialized = true;
         spin_unlock(&parent->shadow_lock);
         return new;
     }
     spin_unlock(&parent->shadow_lock);
     /* protect after insertion, so it will get properly invalidated */
     mmap_read_lock(parent->mm);
     rc = gmap_protect_range(parent, asce & _ASCE_ORIGIN,
                 ((asce & _ASCE_TABLE_LENGTH) + 1) * PAGE_SIZE,
                 PROT_READ, GMAP_NOTIFY_SHADOW);
     mmap_read_unlock(parent->mm);
     spin_lock(&parent->shadow_lock);
     new->initialized = true;
     if (rc) {
         list_del(&new->list);
         gmap_free(new);
         new = ERR_PTR(rc);
     }
     spin_unlock(&parent->shadow_lock);
     return new;
 }
 EXPORT_SYMBOL_GPL(gmap_shadow);
 
 /**
  * gmap_shadow_r2t - create an empty shadow region 2 table
  * @sg: pointer to the shadow guest address space structure
  * @saddr: faulting address in the shadow gmap
  * @r2t: parent gmap address of the region 2 table to get shadowed
  * @fake: r2t references contiguous guest memory block, not a r2t
  *
  * The r2t parameter specifies the address of the source table. The
  * four pages of the source table are made read-only in the parent gmap
  * address space. A write to the source table area @r2t will automatically
  * remove the shadow r2 table and all of its decendents.
  *
  * Returns 0 if successfully shadowed or already shadowed, -EAGAIN if the
  * shadow table structure is incomplete, -ENOMEM if out of memory and
  * -EFAULT if an address in the parent gmap could not be resolved.
  *
  * Called with sg->mm->mmap_lock in read.
  */
 int gmap_shadow_r2t(struct gmap *sg, unsigned long saddr, unsigned long r2t,
             int fake)
 {
     unsigned long raddr, origin, offset, len;
     unsigned long *s_r2t, *table;
     struct page *page;
     int rc;
 
     BUG_ON(!gmap_is_shadow(sg));
     /* Allocate a shadow region second table */
     page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
     if (!page)
         return -ENOMEM;
     page->index = r2t & _REGION_ENTRY_ORIGIN;
     if (fake)
         page->index |= GMAP_SHADOW_FAKE_TABLE;
     s_r2t = (unsigned long *) page_to_phys(page);
     /* Install shadow region second table */
     spin_lock(&sg->guest_table_lock);
     table = gmap_table_walk(sg, saddr, 4); /* get region-1 pointer */
     if (!table) {
         rc = -EAGAIN;       /* Race with unshadow */
         goto out_free;
     }
     if (!(*table & _REGION_ENTRY_INVALID)) {
         rc = 0;         /* Already established */
         goto out_free;
     } else if (*table & _REGION_ENTRY_ORIGIN) {
         rc = -EAGAIN;       /* Race with shadow */
         goto out_free;
     }
     crst_table_init(s_r2t, _REGION2_ENTRY_EMPTY);
     /* mark as invalid as long as the parent table is not protected */
     *table = (unsigned long) s_r2t | _REGION_ENTRY_LENGTH |
          _REGION_ENTRY_TYPE_R1 | _REGION_ENTRY_INVALID;
     if (sg->edat_level >= 1)
         *table |= (r2t & _REGION_ENTRY_PROTECT);
     list_add(&page->lru, &sg->crst_list);
     if (fake) {
         /* nothing to protect for fake tables */
         *table &= ~_REGION_ENTRY_INVALID;
         spin_unlock(&sg->guest_table_lock);
         return 0;
     }
     spin_unlock(&sg->guest_table_lock);
     /* Make r2t read-only in parent gmap page table */
     raddr = (saddr & _REGION1_MASK) | _SHADOW_RMAP_REGION1;
     origin = r2t & _REGION_ENTRY_ORIGIN;
     offset = ((r2t & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
     len = ((r2t & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
     rc = gmap_protect_rmap(sg, raddr, origin + offset, len);
     spin_lock(&sg->guest_table_lock);
     if (!rc) {
         table = gmap_table_walk(sg, saddr, 4);
         if (!table || (*table & _REGION_ENTRY_ORIGIN) !=
                   (unsigned long) s_r2t)
             rc = -EAGAIN;       /* Race with unshadow */
         else
             *table &= ~_REGION_ENTRY_INVALID;
     } else {
         gmap_unshadow_r2t(sg, raddr);
     }
     spin_unlock(&sg->guest_table_lock);
     return rc;
 out_free:
     spin_unlock(&sg->guest_table_lock);
     __free_pages(page, CRST_ALLOC_ORDER);
     return rc;
 }
 EXPORT_SYMBOL_GPL(gmap_shadow_r2t);
 
 /**
  * gmap_shadow_r3t - create a shadow region 3 table
  * @sg: pointer to the shadow guest address space structure
  * @saddr: faulting address in the shadow gmap
  * @r3t: parent gmap address of the region 3 table to get shadowed
  * @fake: r3t references contiguous guest memory block, not a r3t
  *
  * Returns 0 if successfully shadowed or already shadowed, -EAGAIN if the
  * shadow table structure is incomplete, -ENOMEM if out of memory and
  * -EFAULT if an address in the parent gmap could not be resolved.
  *
  * Called with sg->mm->mmap_lock in read.
  */
 int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t,
             int fake)
 {
     unsigned long raddr, origin, offset, len;
     unsigned long *s_r3t, *table;
     struct page *page;
     int rc;
 
     BUG_ON(!gmap_is_shadow(sg));
     /* Allocate a shadow region second table */
     page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
     if (!page)
         return -ENOMEM;
     page->index = r3t & _REGION_ENTRY_ORIGIN;
     if (fake)
         page->index |= GMAP_SHADOW_FAKE_TABLE;
     s_r3t = (unsigned long *) page_to_phys(page);
     /* Install shadow region second table */
     spin_lock(&sg->guest_table_lock);
     table = gmap_table_walk(sg, saddr, 3); /* get region-2 pointer */
     if (!table) {
         rc = -EAGAIN;       /* Race with unshadow */
         goto out_free;
     }
     if (!(*table & _REGION_ENTRY_INVALID)) {
         rc = 0;         /* Already established */
         goto out_free;
     } else if (*table & _REGION_ENTRY_ORIGIN) {
         rc = -EAGAIN;       /* Race with shadow */
         goto out_free;
     }
     crst_table_init(s_r3t, _REGION3_ENTRY_EMPTY);
     /* mark as invalid as long as the parent table is not protected */
     *table = (unsigned long) s_r3t | _REGION_ENTRY_LENGTH |
          _REGION_ENTRY_TYPE_R2 | _REGION_ENTRY_INVALID;
     if (sg->edat_level >= 1)
         *table |= (r3t & _REGION_ENTRY_PROTECT);
     list_add(&page->lru, &sg->crst_list);
     if (fake) {
         /* nothing to protect for fake tables */
         *table &= ~_REGION_ENTRY_INVALID;
         spin_unlock(&sg->guest_table_lock);
         return 0;
     }
     spin_unlock(&sg->guest_table_lock);
     /* Make r3t read-only in parent gmap page table */
     raddr = (saddr & _REGION2_MASK) | _SHADOW_RMAP_REGION2;
     origin = r3t & _REGION_ENTRY_ORIGIN;
     offset = ((r3t & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
     len = ((r3t & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
     rc = gmap_protect_rmap(sg, raddr, origin + offset, len);
     spin_lock(&sg->guest_table_lock);
     if (!rc) {
         table = gmap_table_walk(sg, saddr, 3);
         if (!table || (*table & _REGION_ENTRY_ORIGIN) !=
                   (unsigned long) s_r3t)
             rc = -EAGAIN;       /* Race with unshadow */
         else
             *table &= ~_REGION_ENTRY_INVALID;
     } else {
         gmap_unshadow_r3t(sg, raddr);
     }
     spin_unlock(&sg->guest_table_lock);
     return rc;
 out_free:
     spin_unlock(&sg->guest_table_lock);
     __free_pages(page, CRST_ALLOC_ORDER);
     return rc;
 }
 EXPORT_SYMBOL_GPL(gmap_shadow_r3t);
 
 /**
  * gmap_shadow_sgt - create a shadow segment table
  * @sg: pointer to the shadow guest address space structure
  * @saddr: faulting address in the shadow gmap
  * @sgt: parent gmap address of the segment table to get shadowed
  * @fake: sgt references contiguous guest memory block, not a sgt
  *
  * Returns: 0 if successfully shadowed or already shadowed, -EAGAIN if the
  * shadow table structure is incomplete, -ENOMEM if out of memory and
  * -EFAULT if an address in the parent gmap could not be resolved.
  *
  * Called with sg->mm->mmap_lock in read.
  */
 int gmap_shadow_sgt(struct gmap *sg, unsigned long saddr, unsigned long sgt,
             int fake)
 {
     unsigned long raddr, origin, offset, len;
     unsigned long *s_sgt, *table;
     struct page *page;
     int rc;
 
     BUG_ON(!gmap_is_shadow(sg) || (sgt & _REGION3_ENTRY_LARGE));
     /* Allocate a shadow segment table */
     page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
     if (!page)
         return -ENOMEM;
     page->index = sgt & _REGION_ENTRY_ORIGIN;
     if (fake)
         page->index |= GMAP_SHADOW_FAKE_TABLE;
     s_sgt = (unsigned long *) page_to_phys(page);
     /* Install shadow region second table */
     spin_lock(&sg->guest_table_lock);
     table = gmap_table_walk(sg, saddr, 2); /* get region-3 pointer */
     if (!table) {
         rc = -EAGAIN;       /* Race with unshadow */
         goto out_free;
     }
     if (!(*table & _REGION_ENTRY_INVALID)) {
         rc = 0;         /* Already established */
         goto out_free;
     } else if (*table & _REGION_ENTRY_ORIGIN) {
         rc = -EAGAIN;       /* Race with shadow */
         goto out_free;
     }
     crst_table_init(s_sgt, _SEGMENT_ENTRY_EMPTY);
     /* mark as invalid as long as the parent table is not protected */
     *table = (unsigned long) s_sgt | _REGION_ENTRY_LENGTH |
          _REGION_ENTRY_TYPE_R3 | _REGION_ENTRY_INVALID;
     if (sg->edat_level >= 1)
         *table |= sgt & _REGION_ENTRY_PROTECT;
     list_add(&page->lru, &sg->crst_list);
     if (fake) {
         /* nothing to protect for fake tables */
         *table &= ~_REGION_ENTRY_INVALID;
         spin_unlock(&sg->guest_table_lock);
         return 0;
     }
     spin_unlock(&sg->guest_table_lock);
     /* Make sgt read-only in parent gmap page table */
     raddr = (saddr & _REGION3_MASK) | _SHADOW_RMAP_REGION3;
     origin = sgt & _REGION_ENTRY_ORIGIN;
     offset = ((sgt & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
     len = ((sgt & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
     rc = gmap_protect_rmap(sg, raddr, origin + offset, len);
     spin_lock(&sg->guest_table_lock);
     if (!rc) {
         table = gmap_table_walk(sg, saddr, 2);
         if (!table || (*table & _REGION_ENTRY_ORIGIN) !=
                   (unsigned long) s_sgt)
             rc = -EAGAIN;       /* Race with unshadow */
         else
             *table &= ~_REGION_ENTRY_INVALID;
     } else {
         gmap_unshadow_sgt(sg, raddr);
     }
     spin_unlock(&sg->guest_table_lock);
     return rc;
 out_free:
     spin_unlock(&sg->guest_table_lock);
     __free_pages(page, CRST_ALLOC_ORDER);
     return rc;
 }
 EXPORT_SYMBOL_GPL(gmap_shadow_sgt);
 
 /**
  * gmap_shadow_pgt_lookup - find a shadow page table
  * @sg: pointer to the shadow guest address space structure
  * @saddr: the address in the shadow aguest address space
  * @pgt: parent gmap address of the page table to get shadowed
  * @dat_protection: if the pgtable is marked as protected by dat
  * @fake: pgt references contiguous guest memory block, not a pgtable
  *
  * Returns 0 if the shadow page table was found and -EAGAIN if the page
  * table was not found.
  *
  * Called with sg->mm->mmap_lock in read.
  */
 int gmap_shadow_pgt_lookup(struct gmap *sg, unsigned long saddr,
                unsigned long *pgt, int *dat_protection,
                int *fake)
 {
     unsigned long *table;
     struct page *page;
     int rc;
 
     BUG_ON(!gmap_is_shadow(sg));
     spin_lock(&sg->guest_table_lock);
     table = gmap_table_walk(sg, saddr, 1); /* get segment pointer */
     if (table && !(*table & _SEGMENT_ENTRY_INVALID)) {
         /* Shadow page tables are full pages (pte+pgste) */
         page = pfn_to_page(*table >> PAGE_SHIFT);
         *pgt = page->index & ~GMAP_SHADOW_FAKE_TABLE;
         *dat_protection = !!(*table & _SEGMENT_ENTRY_PROTECT);
         *fake = !!(page->index & GMAP_SHADOW_FAKE_TABLE);
         rc = 0;
     } else  {
         rc = -EAGAIN;
     }
     spin_unlock(&sg->guest_table_lock);
     return rc;
 
 }
 EXPORT_SYMBOL_GPL(gmap_shadow_pgt_lookup);
 
 /**
  * gmap_shadow_pgt - instantiate a shadow page table
  * @sg: pointer to the shadow guest address space structure
  * @saddr: faulting address in the shadow gmap
  * @pgt: parent gmap address of the page table to get shadowed
  * @fake: pgt references contiguous guest memory block, not a pgtable
  *
  * Returns 0 if successfully shadowed or already shadowed, -EAGAIN if the
  * shadow table structure is incomplete, -ENOMEM if out of memory,
  * -EFAULT if an address in the parent gmap could not be resolved and
  *
  * Called with gmap->mm->mmap_lock in read
  */
 int gmap_shadow_pgt(struct gmap *sg, unsigned long saddr, unsigned long pgt,
             int fake)
 {
     unsigned long raddr, origin;
     unsigned long *s_pgt, *table;
     struct page *page;
     int rc;
 
     BUG_ON(!gmap_is_shadow(sg) || (pgt & _SEGMENT_ENTRY_LARGE));
     /* Allocate a shadow page table */
     page = page_table_alloc_pgste(sg->mm);
     if (!page)
         return -ENOMEM;
     page->index = pgt & _SEGMENT_ENTRY_ORIGIN;
     if (fake)
         page->index |= GMAP_SHADOW_FAKE_TABLE;
     s_pgt = (unsigned long *) page_to_phys(page);
     /* Install shadow page table */
     spin_lock(&sg->guest_table_lock);
     table = gmap_table_walk(sg, saddr, 1); /* get segment pointer */
     if (!table) {
         rc = -EAGAIN;       /* Race with unshadow */
         goto out_free;
     }
     if (!(*table & _SEGMENT_ENTRY_INVALID)) {
         rc = 0;         /* Already established */
         goto out_free;
     } else if (*table & _SEGMENT_ENTRY_ORIGIN) {
         rc = -EAGAIN;       /* Race with shadow */
         goto out_free;
     }
     /* mark as invalid as long as the parent table is not protected */
     *table = (unsigned long) s_pgt | _SEGMENT_ENTRY |
          (pgt & _SEGMENT_ENTRY_PROTECT) | _SEGMENT_ENTRY_INVALID;
     list_add(&page->lru, &sg->pt_list);
     if (fake) {
         /* nothing to protect for fake tables */
         *table &= ~_SEGMENT_ENTRY_INVALID;
         spin_unlock(&sg->guest_table_lock);
         return 0;
     }
     spin_unlock(&sg->guest_table_lock);
     /* Make pgt read-only in parent gmap page table (not the pgste) */
     raddr = (saddr & _SEGMENT_MASK) | _SHADOW_RMAP_SEGMENT;
     origin = pgt & _SEGMENT_ENTRY_ORIGIN & PAGE_MASK;
     rc = gmap_protect_rmap(sg, raddr, origin, PAGE_SIZE);
     spin_lock(&sg->guest_table_lock);
     if (!rc) {
         table = gmap_table_walk(sg, saddr, 1);
         if (!table || (*table & _SEGMENT_ENTRY_ORIGIN) !=
                   (unsigned long) s_pgt)
             rc = -EAGAIN;       /* Race with unshadow */
         else
             *table &= ~_SEGMENT_ENTRY_INVALID;
     } else {
         gmap_unshadow_pgt(sg, raddr);
     }
     spin_unlock(&sg->guest_table_lock);
     return rc;
 out_free:
     spin_unlock(&sg->guest_table_lock);
     page_table_free_pgste(page);
     return rc;
 
 }
 EXPORT_SYMBOL_GPL(gmap_shadow_pgt);
 
 /**
  * gmap_shadow_page - create a shadow page mapping
  * @sg: pointer to the shadow guest address space structure
  * @saddr: faulting address in the shadow gmap
  * @pte: pte in parent gmap address space to get shadowed
  *
  * Returns 0 if successfully shadowed or already shadowed, -EAGAIN if the
  * shadow table structure is incomplete, -ENOMEM if out of memory and
  * -EFAULT if an address in the parent gmap could not be resolved.
  *
  * Called with sg->mm->mmap_lock in read.
  */
 int gmap_shadow_page(struct gmap *sg, unsigned long saddr, pte_t pte)
 {
     struct gmap *parent;
     struct gmap_rmap *rmap;
     unsigned long vmaddr, paddr;
     spinlock_t *ptl;
     pte_t *sptep, *tptep;
     int prot;
     int rc;
 
     BUG_ON(!gmap_is_shadow(sg));
     parent = sg->parent;
     prot = (pte_val(pte) & _PAGE_PROTECT) ? PROT_READ : PROT_WRITE;
 
     rmap = kzalloc(sizeof(*rmap), GFP_KERNEL_ACCOUNT);
     if (!rmap)
         return -ENOMEM;
     rmap->raddr = (saddr & PAGE_MASK) | _SHADOW_RMAP_PGTABLE;
 
     while (1) {
         paddr = pte_val(pte) & PAGE_MASK;
         vmaddr = __gmap_translate(parent, paddr);
         if (IS_ERR_VALUE(vmaddr)) {
             rc = vmaddr;
             break;
         }
         rc = radix_tree_preload(GFP_KERNEL_ACCOUNT);
         if (rc)
             break;
         rc = -EAGAIN;
         sptep = gmap_pte_op_walk(parent, paddr, &ptl);
         if (sptep) {
             spin_lock(&sg->guest_table_lock);
             /* Get page table pointer */
             tptep = (pte_t *) gmap_table_walk(sg, saddr, 0);
             if (!tptep) {
                 spin_unlock(&sg->guest_table_lock);
                 gmap_pte_op_end(ptl);
                 radix_tree_preload_end();
                 break;
             }
             rc = ptep_shadow_pte(sg->mm, saddr, sptep, tptep, pte);
             if (rc > 0) {
                 /* Success and a new mapping */
                 gmap_insert_rmap(sg, vmaddr, rmap);
                 rmap = NULL;
                 rc = 0;
             }
             gmap_pte_op_end(ptl);
             spin_unlock(&sg->guest_table_lock);
         }
         radix_tree_preload_end();
         if (!rc)
             break;
         rc = gmap_pte_op_fixup(parent, paddr, vmaddr, prot);
         if (rc)
             break;
     }
     kfree(rmap);
     return rc;
 }
 EXPORT_SYMBOL_GPL(gmap_shadow_page);
 
 /*
  * gmap_shadow_notify - handle notifications for shadow gmap
  *
  * Called with sg->parent->shadow_lock.
  */
 static void gmap_shadow_notify(struct gmap *sg, unsigned long vmaddr,
                    unsigned long gaddr)
 {
     struct gmap_rmap *rmap, *rnext, *head;
     unsigned long start, end, bits, raddr;
 
     BUG_ON(!gmap_is_shadow(sg));
 
     spin_lock(&sg->guest_table_lock);
     if (sg->removed) {
         spin_unlock(&sg->guest_table_lock);
         return;
     }
     /* Check for top level table */
     start = sg->orig_asce & _ASCE_ORIGIN;
     end = start + ((sg->orig_asce & _ASCE_TABLE_LENGTH) + 1) * PAGE_SIZE;
     if (!(sg->orig_asce & _ASCE_REAL_SPACE) && gaddr >= start &&
         gaddr < end) {
         /* The complete shadow table has to go */
         gmap_unshadow(sg);
         spin_unlock(&sg->guest_table_lock);
         list_del(&sg->list);
         gmap_put(sg);
         return;
     }
     /* Remove the page table tree from on specific entry */
     head = radix_tree_delete(&sg->host_to_rmap, vmaddr >> PAGE_SHIFT);
     gmap_for_each_rmap_safe(rmap, rnext, head) {
         bits = rmap->raddr & _SHADOW_RMAP_MASK;
         raddr = rmap->raddr ^ bits;
         switch (bits) {
         case _SHADOW_RMAP_REGION1:
             gmap_unshadow_r2t(sg, raddr);
             break;
         case _SHADOW_RMAP_REGION2:
             gmap_unshadow_r3t(sg, raddr);
             break;
         case _SHADOW_RMAP_REGION3:
             gmap_unshadow_sgt(sg, raddr);
             break;
         case _SHADOW_RMAP_SEGMENT:
             gmap_unshadow_pgt(sg, raddr);
             break;
         case _SHADOW_RMAP_PGTABLE:
             gmap_unshadow_page(sg, raddr);
             break;
         }
         kfree(rmap);
     }
     spin_unlock(&sg->guest_table_lock);
 }
 
 /**
  * ptep_notify - call all invalidation callbacks for a specific pte.
  * @mm: pointer to the process mm_struct
  * @vmaddr: virtual address in the process address space
  * @pte: pointer to the page table entry
  * @bits: bits from the pgste that caused the notify call
  *
  * This function is assumed to be called with the page table lock held
  * for the pte to notify.
  */
 void ptep_notify(struct mm_struct *mm, unsigned long vmaddr,
          pte_t *pte, unsigned long bits)
 {
     unsigned long offset, gaddr = 0;
     unsigned long *table;
     struct gmap *gmap, *sg, *next;
 
     offset = ((unsigned long) pte) & (255 * sizeof(pte_t));
     offset = offset * (PAGE_SIZE / sizeof(pte_t));
     rcu_read_lock();
     list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
         spin_lock(&gmap->guest_table_lock);
         table = radix_tree_lookup(&gmap->host_to_guest,
                       vmaddr >> PMD_SHIFT);
         if (table)
             gaddr = __gmap_segment_gaddr(table) + offset;
         spin_unlock(&gmap->guest_table_lock);
         if (!table)
             continue;
 
         if (!list_empty(&gmap->children) && (bits & PGSTE_VSIE_BIT)) {
             spin_lock(&gmap->shadow_lock);
             list_for_each_entry_safe(sg, next,
                          &gmap->children, list)
                 gmap_shadow_notify(sg, vmaddr, gaddr);
             spin_unlock(&gmap->shadow_lock);
         }
         if (bits & PGSTE_IN_BIT)
             gmap_call_notifier(gmap, gaddr, gaddr + PAGE_SIZE - 1);
     }
     rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(ptep_notify);
 
 static void pmdp_notify_gmap(struct gmap *gmap, pmd_t *pmdp,
                  unsigned long gaddr)
 {
     set_pmd(pmdp, clear_pmd_bit(*pmdp, __pgprot(_SEGMENT_ENTRY_GMAP_IN)));
     gmap_call_notifier(gmap, gaddr, gaddr + HPAGE_SIZE - 1);
 }
 
 /**
  * gmap_pmdp_xchg - exchange a gmap pmd with another
  * @gmap: pointer to the guest address space structure
  * @pmdp: pointer to the pmd entry
  * @new: replacement entry
  * @gaddr: the affected guest address
  *
  * This function is assumed to be called with the guest_table_lock
  * held.
  */
 static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *pmdp, pmd_t new,
                unsigned long gaddr)
 {
     gaddr &= HPAGE_MASK;
     pmdp_notify_gmap(gmap, pmdp, gaddr);
     new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_GMAP_IN));
     if (MACHINE_HAS_TLB_GUEST)
         __pmdp_idte(gaddr, (pmd_t *)pmdp, IDTE_GUEST_ASCE, gmap->asce,
                 IDTE_GLOBAL);
     else if (MACHINE_HAS_IDTE)
         __pmdp_idte(gaddr, (pmd_t *)pmdp, 0, 0, IDTE_GLOBAL);
     else
         __pmdp_csp(pmdp);
     set_pmd(pmdp, new);
 }
 
 static void gmap_pmdp_clear(struct mm_struct *mm, unsigned long vmaddr,
                 int purge)
 {
     pmd_t *pmdp;
     struct gmap *gmap;
     unsigned long gaddr;
 
     rcu_read_lock();
     list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
         spin_lock(&gmap->guest_table_lock);
         pmdp = (pmd_t *)radix_tree_delete(&gmap->host_to_guest,
                           vmaddr >> PMD_SHIFT);
         if (pmdp) {
             gaddr = __gmap_segment_gaddr((unsigned long *)pmdp);
             pmdp_notify_gmap(gmap, pmdp, gaddr);
             WARN_ON(pmd_val(*pmdp) & ~(_SEGMENT_ENTRY_HARDWARE_BITS_LARGE |
                            _SEGMENT_ENTRY_GMAP_UC));
             if (purge)
                 __pmdp_csp(pmdp);
             set_pmd(pmdp, __pmd(_SEGMENT_ENTRY_EMPTY));
         }
         spin_unlock(&gmap->guest_table_lock);
     }
     rcu_read_unlock();
 }
 
 /**
  * gmap_pmdp_invalidate - invalidate all affected guest pmd entries without
  *                        flushing
  * @mm: pointer to the process mm_struct
  * @vmaddr: virtual address in the process address space
  */
 void gmap_pmdp_invalidate(struct mm_struct *mm, unsigned long vmaddr)
 {
     gmap_pmdp_clear(mm, vmaddr, 0);
 }
 EXPORT_SYMBOL_GPL(gmap_pmdp_invalidate);
 
 /**
  * gmap_pmdp_csp - csp all affected guest pmd entries
  * @mm: pointer to the process mm_struct
  * @vmaddr: virtual address in the process address space
  */
 void gmap_pmdp_csp(struct mm_struct *mm, unsigned long vmaddr)
 {
     gmap_pmdp_clear(mm, vmaddr, 1);
 }
 EXPORT_SYMBOL_GPL(gmap_pmdp_csp);
 
 /**
  * gmap_pmdp_idte_local - invalidate and clear a guest pmd entry
  * @mm: pointer to the process mm_struct
  * @vmaddr: virtual address in the process address space
  */
 void gmap_pmdp_idte_local(struct mm_struct *mm, unsigned long vmaddr)
 {
     unsigned long *entry, gaddr;
     struct gmap *gmap;
     pmd_t *pmdp;
 
     rcu_read_lock();
     list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
         spin_lock(&gmap->guest_table_lock);
         entry = radix_tree_delete(&gmap->host_to_guest,
                       vmaddr >> PMD_SHIFT);
         if (entry) {
             pmdp = (pmd_t *)entry;
             gaddr = __gmap_segment_gaddr(entry);
             pmdp_notify_gmap(gmap, pmdp, gaddr);
             WARN_ON(*entry & ~(_SEGMENT_ENTRY_HARDWARE_BITS_LARGE |
                        _SEGMENT_ENTRY_GMAP_UC));
             if (MACHINE_HAS_TLB_GUEST)
                 __pmdp_idte(gaddr, pmdp, IDTE_GUEST_ASCE,
                         gmap->asce, IDTE_LOCAL);
             else if (MACHINE_HAS_IDTE)
                 __pmdp_idte(gaddr, pmdp, 0, 0, IDTE_LOCAL);
             *entry = _SEGMENT_ENTRY_EMPTY;
         }
         spin_unlock(&gmap->guest_table_lock);
     }
     rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(gmap_pmdp_idte_local);
 
 /**
  * gmap_pmdp_idte_global - invalidate and clear a guest pmd entry
  * @mm: pointer to the process mm_struct
  * @vmaddr: virtual address in the process address space
  */
 void gmap_pmdp_idte_global(struct mm_struct *mm, unsigned long vmaddr)
 {
     unsigned long *entry, gaddr;
     struct gmap *gmap;
     pmd_t *pmdp;
 
     rcu_read_lock();
     list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
         spin_lock(&gmap->guest_table_lock);
         entry = radix_tree_delete(&gmap->host_to_guest,
                       vmaddr >> PMD_SHIFT);
         if (entry) {
             pmdp = (pmd_t *)entry;
             gaddr = __gmap_segment_gaddr(entry);
             pmdp_notify_gmap(gmap, pmdp, gaddr);
             WARN_ON(*entry & ~(_SEGMENT_ENTRY_HARDWARE_BITS_LARGE |
                        _SEGMENT_ENTRY_GMAP_UC));
             if (MACHINE_HAS_TLB_GUEST)
                 __pmdp_idte(gaddr, pmdp, IDTE_GUEST_ASCE,
                         gmap->asce, IDTE_GLOBAL);
             else if (MACHINE_HAS_IDTE)
                 __pmdp_idte(gaddr, pmdp, 0, 0, IDTE_GLOBAL);
             else
                 __pmdp_csp(pmdp);
             *entry = _SEGMENT_ENTRY_EMPTY;
         }
         spin_unlock(&gmap->guest_table_lock);
     }
     rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(gmap_pmdp_idte_global);
 
 /**
  * gmap_test_and_clear_dirty_pmd - test and reset segment dirty status
  * @gmap: pointer to guest address space
  * @pmdp: pointer to the pmd to be tested
  * @gaddr: virtual address in the guest address space
  *
  * This function is assumed to be called with the guest_table_lock
  * held.
  */
 static bool gmap_test_and_clear_dirty_pmd(struct gmap *gmap, pmd_t *pmdp,
                       unsigned long gaddr)
 {
     if (pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)
         return false;
 
     /* Already protected memory, which did not change is clean */
     if (pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT &&
         !(pmd_val(*pmdp) & _SEGMENT_ENTRY_GMAP_UC))
         return false;
 
     /* Clear UC indication and reset protection */
     set_pmd(pmdp, clear_pmd_bit(*pmdp, __pgprot(_SEGMENT_ENTRY_GMAP_UC)));
     gmap_protect_pmd(gmap, gaddr, pmdp, PROT_READ, 0);
     return true;
 }
 
 /**
  * gmap_sync_dirty_log_pmd - set bitmap based on dirty status of segment
  * @gmap: pointer to guest address space
  * @bitmap: dirty bitmap for this pmd
  * @gaddr: virtual address in the guest address space
  * @vmaddr: virtual address in the host address space
  *
  * This function is assumed to be called with the guest_table_lock
  * held.
  */
 void gmap_sync_dirty_log_pmd(struct gmap *gmap, unsigned long bitmap[4],
                  unsigned long gaddr, unsigned long vmaddr)
 {
     int i;
     pmd_t *pmdp;
     pte_t *ptep;
     spinlock_t *ptl;
 
     pmdp = gmap_pmd_op_walk(gmap, gaddr);
     if (!pmdp)
         return;
 
     if (pmd_large(*pmdp)) {
         if (gmap_test_and_clear_dirty_pmd(gmap, pmdp, gaddr))
             bitmap_fill(bitmap, _PAGE_ENTRIES);
     } else {
         for (i = 0; i < _PAGE_ENTRIES; i++, vmaddr += PAGE_SIZE) {
             ptep = pte_alloc_map_lock(gmap->mm, pmdp, vmaddr, &ptl);
             if (!ptep)
                 continue;
             if (ptep_test_and_clear_uc(gmap->mm, vmaddr, ptep))
                 set_bit(i, bitmap);
             spin_unlock(ptl);
         }
     }
     gmap_pmd_op_end(gmap, pmdp);
 }
 EXPORT_SYMBOL_GPL(gmap_sync_dirty_log_pmd);
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static int thp_split_walk_pmd_entry(pmd_t *pmd, unsigned long addr,
                     unsigned long end, struct mm_walk *walk)
 {
     struct vm_area_struct *vma = walk->vma;
 
     split_huge_pmd(vma, pmd, addr);
     return 0;
 }
 
 static const struct mm_walk_ops thp_split_walk_ops = {
     .pmd_entry  = thp_split_walk_pmd_entry,
 };
 
 static inline void thp_split_mm(struct mm_struct *mm)
 {
     struct vm_area_struct *vma;
 
     for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
         vma->vm_flags &= ~VM_HUGEPAGE;
         vma->vm_flags |= VM_NOHUGEPAGE;
         walk_page_vma(vma, &thp_split_walk_ops, NULL);
     }
     mm->def_flags |= VM_NOHUGEPAGE;
 }
 #else
 static inline void thp_split_mm(struct mm_struct *mm)
 {
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 /*
  * Remove all empty zero pages from the mapping for lazy refaulting
  * - This must be called after mm->context.has_pgste is set, to avoid
  *   future creation of zero pages
  * - This must be called after THP was enabled
  */
 static int __zap_zero_pages(pmd_t *pmd, unsigned long start,
                unsigned long end, struct mm_walk *walk)
 {
     unsigned long addr;
 
     for (addr = start; addr != end; addr += PAGE_SIZE) {
         pte_t *ptep;
         spinlock_t *ptl;
 
         ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
         if (is_zero_pfn(pte_pfn(*ptep)))
             ptep_xchg_direct(walk->mm, addr, ptep, __pte(_PAGE_INVALID));
         pte_unmap_unlock(ptep, ptl);
     }
     return 0;
 }
 
 static const struct mm_walk_ops zap_zero_walk_ops = {
     .pmd_entry  = __zap_zero_pages,
 };
 
 /*
  * switch on pgstes for its userspace process (for kvm)
  */
 int s390_enable_sie(void)
 {
     struct mm_struct *mm = current->mm;
 
     /* Do we have pgstes? if yes, we are done */
     if (mm_has_pgste(mm))
         return 0;
     /* Fail if the page tables are 2K */
     if (!mm_alloc_pgste(mm))
         return -EINVAL;
     mmap_write_lock(mm);
     mm->context.has_pgste = 1;
     /* split thp mappings and disable thp for future mappings */
     thp_split_mm(mm);
     walk_page_range(mm, 0, TASK_SIZE, &zap_zero_walk_ops, NULL);
     mmap_write_unlock(mm);
     return 0;
 }
 EXPORT_SYMBOL_GPL(s390_enable_sie);
 
 int gmap_mark_unmergeable(void)
 {
     struct mm_struct *mm = current->mm;
     struct vm_area_struct *vma;
     int ret;
 
     for (vma = mm->mmap; vma; vma = vma->vm_next) {
         ret = ksm_madvise(vma, vma->vm_start, vma->vm_end,
                   MADV_UNMERGEABLE, &vma->vm_flags);
         if (ret)
             return ret;
     }
     mm->def_flags &= ~VM_MERGEABLE;
     return 0;
 }
 EXPORT_SYMBOL_GPL(gmap_mark_unmergeable);
 
 /*
  * Enable storage key handling from now on and initialize the storage
  * keys with the default key.
  */
 static int __s390_enable_skey_pte(pte_t *pte, unsigned long addr,
                   unsigned long next, struct mm_walk *walk)
 {
     /* Clear storage key */
     ptep_zap_key(walk->mm, addr, pte);
     return 0;
 }
 
 /*
  * Give a chance to schedule after setting a key to 256 pages.
  * We only hold the mm lock, which is a rwsem and the kvm srcu.
  * Both can sleep.
  */
 static int __s390_enable_skey_pmd(pmd_t *pmd, unsigned long addr,
                   unsigned long next, struct mm_walk *walk)
 {
     cond_resched();
     return 0;
 }
 
 static int __s390_enable_skey_hugetlb(pte_t *pte, unsigned long addr,
                       unsigned long hmask, unsigned long next,
                       struct mm_walk *walk)
 {
     pmd_t *pmd = (pmd_t *)pte;
     unsigned long start, end;
     struct page *page = pmd_page(*pmd);
 
     /*
      * The write check makes sure we do not set a key on shared
      * memory. This is needed as the walker does not differentiate
      * between actual guest memory and the process executable or
      * shared libraries.
      */
     if (pmd_val(*pmd) & _SEGMENT_ENTRY_INVALID ||
         !(pmd_val(*pmd) & _SEGMENT_ENTRY_WRITE))
         return 0;
 
     start = pmd_val(*pmd) & HPAGE_MASK;
     end = start + HPAGE_SIZE - 1;
     __storage_key_init_range(start, end);
     set_bit(PG_arch_1, &page->flags);
     cond_resched();
     return 0;
 }
 
 static const struct mm_walk_ops enable_skey_walk_ops = {
     .hugetlb_entry      = __s390_enable_skey_hugetlb,
     .pte_entry      = __s390_enable_skey_pte,
     .pmd_entry      = __s390_enable_skey_pmd,
 };
 
 int s390_enable_skey(void)
 {
     struct mm_struct *mm = current->mm;
     int rc = 0;
 
     mmap_write_lock(mm);
     if (mm_uses_skeys(mm))
         goto out_up;
 
     mm->context.uses_skeys = 1;
     rc = gmap_mark_unmergeable();
     if (rc) {
         mm->context.uses_skeys = 0;
         goto out_up;
     }
     walk_page_range(mm, 0, TASK_SIZE, &enable_skey_walk_ops, NULL);
 
 out_up:
     mmap_write_unlock(mm);
     return rc;
 }
 EXPORT_SYMBOL_GPL(s390_enable_skey);
 
 /*
  * Reset CMMA state, make all pages stable again.
  */
 static int __s390_reset_cmma(pte_t *pte, unsigned long addr,
                  unsigned long next, struct mm_walk *walk)
 {
     ptep_zap_unused(walk->mm, addr, pte, 1);
     return 0;
 }
 
 static const struct mm_walk_ops reset_cmma_walk_ops = {
     .pte_entry      = __s390_reset_cmma,
 };
 
 void s390_reset_cmma(struct mm_struct *mm)
 {
     mmap_write_lock(mm);
     walk_page_range(mm, 0, TASK_SIZE, &reset_cmma_walk_ops, NULL);
     mmap_write_unlock(mm);
 }
 EXPORT_SYMBOL_GPL(s390_reset_cmma);
 
 #define GATHER_GET_PAGES 32
 
 struct reset_walk_state {
     unsigned long next;
     unsigned long count;
     unsigned long pfns[GATHER_GET_PAGES];
 };
 
 static int s390_gather_pages(pte_t *ptep, unsigned long addr,
                  unsigned long next, struct mm_walk *walk)
 {
     struct reset_walk_state *p = walk->private;
     pte_t pte = READ_ONCE(*ptep);
 
     if (pte_present(pte)) {
         /* we have a reference from the mapping, take an extra one */
         get_page(phys_to_page(pte_val(pte)));
         p->pfns[p->count] = phys_to_pfn(pte_val(pte));
         p->next = next;
         p->count++;
     }
     return p->count >= GATHER_GET_PAGES;
 }
 
 static const struct mm_walk_ops gather_pages_ops = {
     .pte_entry = s390_gather_pages,
 };
 
 /*
  * Call the Destroy secure page UVC on each page in the given array of PFNs.
  * Each page needs to have an extra reference, which will be released here.
  */
 void s390_uv_destroy_pfns(unsigned long count, unsigned long *pfns)
 {
     unsigned long i;
 
     for (i = 0; i < count; i++) {
         /* we always have an extra reference */
         uv_destroy_owned_page(pfn_to_phys(pfns[i]));
         /* get rid of the extra reference */
         put_page(pfn_to_page(pfns[i]));
         cond_resched();
     }
 }
 EXPORT_SYMBOL_GPL(s390_uv_destroy_pfns);
 
 /**
  * __s390_uv_destroy_range - Call the destroy secure page UVC on each page
  * in the given range of the given address space.
  * @mm: the mm to operate on
  * @start: the start of the range
  * @end: the end of the range
  * @interruptible: if not 0, stop when a fatal signal is received
  *
  * Walk the given range of the given address space and call the destroy
  * secure page UVC on each page. Optionally exit early if a fatal signal is
  * pending.
  *
  * Return: 0 on success, -EINTR if the function stopped before completing
  */
 int __s390_uv_destroy_range(struct mm_struct *mm, unsigned long start,
                 unsigned long end, bool interruptible)
 {
     struct reset_walk_state state = { .next = start };
     int r = 1;
 
     while (r > 0) {
         state.count = 0;
         mmap_read_lock(mm);
         r = walk_page_range(mm, state.next, end, &gather_pages_ops, &state);
         mmap_read_unlock(mm);
         cond_resched();
         s390_uv_destroy_pfns(state.count, state.pfns);
         if (interruptible && fatal_signal_pending(current))
             return -EINTR;
     }
     return 0;
 }
 EXPORT_SYMBOL_GPL(__s390_uv_destroy_range);
 
 /**
  * s390_unlist_old_asce - Remove the topmost level of page tables from the
  * list of page tables of the gmap.
  * @gmap: the gmap whose table is to be removed
  *
  * On s390x, KVM keeps a list of all pages containing the page tables of the
  * gmap (the CRST list). This list is used at tear down time to free all
  * pages that are now not needed anymore.
  *
  * This function removes the topmost page of the tree (the one pointed to by
  * the ASCE) from the CRST list.
  *
  * This means that it will not be freed when the VM is torn down, and needs
  * to be handled separately by the caller, unless a leak is actually
  * intended. Notice that this function will only remove the page from the
  * list, the page will still be used as a top level page table (and ASCE).
  */
 void s390_unlist_old_asce(struct gmap *gmap)
 {
     struct page *old;
 
     old = virt_to_page(gmap->table);
     spin_lock(&gmap->guest_table_lock);
     list_del(&old->lru);
     /*
      * Sometimes the topmost page might need to be "removed" multiple
      * times, for example if the VM is rebooted into secure mode several
      * times concurrently, or if s390_replace_asce fails after calling
      * s390_remove_old_asce and is attempted again later. In that case
      * the old asce has been removed from the list, and therefore it
      * will not be freed when the VM terminates, but the ASCE is still
      * in use and still pointed to.
      * A subsequent call to replace_asce will follow the pointer and try
      * to remove the same page from the list again.
      * Therefore it's necessary that the page of the ASCE has valid
      * pointers, so list_del can work (and do nothing) without
      * dereferencing stale or invalid pointers.
      */
     INIT_LIST_HEAD(&old->lru);
     spin_unlock(&gmap->guest_table_lock);
 }
 EXPORT_SYMBOL_GPL(s390_unlist_old_asce);
 
 /**
  * s390_replace_asce - Try to replace the current ASCE of a gmap with a copy
  * @gmap: the gmap whose ASCE needs to be replaced
  *
  * If the allocation of the new top level page table fails, the ASCE is not
  * replaced.
  * In any case, the old ASCE is always removed from the gmap CRST list.
  * Therefore the caller has to make sure to save a pointer to it
  * beforehand, unless a leak is actually intended.
  */
 int s390_replace_asce(struct gmap *gmap)
 {
     unsigned long asce;
     struct page *page;
     void *table;
 
     s390_unlist_old_asce(gmap);
 
     page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
     if (!page)
         return -ENOMEM;
     table = page_to_virt(page);
     memcpy(table, gmap->table, 1UL << (CRST_ALLOC_ORDER + PAGE_SHIFT));
 
     /*
      * The caller has to deal with the old ASCE, but here we make sure
      * the new one is properly added to the CRST list, so that
      * it will be freed when the VM is torn down.
      */
     spin_lock(&gmap->guest_table_lock);
     list_add(&page->lru, &gmap->crst_list);
     spin_unlock(&gmap->guest_table_lock);
 
     /* Set new table origin while preserving existing ASCE control bits */
     asce = (gmap->asce & ~_ASCE_ORIGIN) | __pa(table);
     WRITE_ONCE(gmap->asce, asce);
     WRITE_ONCE(gmap->mm->context.gmap_asce, asce);
     WRITE_ONCE(gmap->table, table);
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(s390_replace_asce);