TOMOYO Linux Cross Reference
Linux/arch/s390/mm/gmap.c

   // 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/page-states.h>
  #include <asm/pgalloc.h>
  #include <asm/gmap.h>
  #include <asm/page.h>
  #include <asm/tlb.h>
  
  #define GMAP_SHADOW_FAKE_TABLE 1ULL
  
  static struct page *gmap_alloc_crst(void)
  {
          struct page *page;
  
          page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
          if (!page)
                  return NULL;
          __arch_set_page_dat(page_to_virt(page), 1UL << CRST_ALLOC_ORDER);
          return page;
  }
  
  /**
   * 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 = gmap_alloc_crst();
          if (!page)
                  goto out_free;
          page->index = 0;
          list_add(&page->lru, &gmap->crst_list);
          table = page_to_virt(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)) {
                 struct ptdesc *ptdesc, *n;
 
                 /* Free all page tables. */
                 list_for_each_entry_safe(ptdesc, n, &gmap->pt_list, pt_list)
                         page_table_free_pgste(ptdesc);
                 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)
 {
         get_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)
 {
         get_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 *)get_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 = gmap_alloc_crst();
         if (!page)
                 return -ENOMEM;
         new = page_to_virt(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 = __pa(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;
 
         offset = (unsigned long) entry / sizeof(unsigned long);
         offset = (offset & (PTRS_PER_PMD - 1)) * PMD_SIZE;
         page = pmd_pgtable_page((pmd_t *) entry);
         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 = __va(*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 = __va(*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 = __va(*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_leaf(*pud))
                 return -EFAULT;
         pmd = pmd_offset(pud, vmaddr);
         VM_BUG_ON(pmd_none(*pmd));
         /* Are we allowed to use huge pages? */
         if (pmd_leaf(*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_leaf(*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_single(vma, vmaddr, size, NULL);
         }
         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 = __va(*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 = __va(*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 = __va(*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 = __va(*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
  * @ptep: pointer to the locked pte
  * @ptl: pointer to the page table spinlock
  */
 static void gmap_pte_op_end(pte_t *ptep, spinlock_t *ptl)
 {
         pte_unmap_unlock(ptep, 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_leaf(*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_leaf(*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;
         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(ptep, 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_leaf(*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 *)__va(address);
                                 set_pte(ptep, set_pte_bit(*ptep, __pgprot(_PAGE_YOUNG)));
                                 /* Do *NOT* clear the _PAGE_INVALID bit! */
                                 rc = 0;
                         }
                         gmap_pte_op_end(ptep, 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(ptep, 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 *ste;
         phys_addr_t sto, pgt;
         struct ptdesc *ptdesc;
 
         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 = __pa(ste - ((raddr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT));
         gmap_idte_one(sto | _ASCE_TYPE_SEGMENT, raddr);
         pgt = *ste & _SEGMENT_ENTRY_ORIGIN;
         *ste = _SEGMENT_ENTRY_EMPTY;
         __gmap_unshadow_pgt(sg, raddr, __va(pgt));
         /* Free page table */
         ptdesc = page_ptdesc(phys_to_page(pgt));
         list_del(&ptdesc->pt_list);
         page_table_free_pgste(ptdesc);
 }
 
 /**
  * __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)
 {
         struct ptdesc *ptdesc;
         phys_addr_t pgt;
         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 = sgt[i] & _REGION_ENTRY_ORIGIN;
                 sgt[i] = _SEGMENT_ENTRY_EMPTY;
                 __gmap_unshadow_pgt(sg, raddr, __va(pgt));
                 /* Free page table */
                 ptdesc = page_ptdesc(phys_to_page(pgt));
                 list_del(&ptdesc->pt_list);
                 page_table_free_pgste(ptdesc);
         }
 }
 
 /**
  * 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;
         phys_addr_t 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(__pa(r3o) | _ASCE_TYPE_REGION3, raddr);
         sgt = *r3e & _REGION_ENTRY_ORIGIN;
         *r3e = _REGION3_ENTRY_EMPTY;
         __gmap_unshadow_sgt(sg, raddr, __va(sgt));
         /* Free segment table */
         page = phys_to_page(sgt);
         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)
 {
         struct page *page;
         phys_addr_t sgt;
         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 = r3t[i] & _REGION_ENTRY_ORIGIN;
                 r3t[i] = _REGION3_ENTRY_EMPTY;
                 __gmap_unshadow_sgt(sg, raddr, __va(sgt));
                 /* Free segment table */
                 page = phys_to_page(sgt);
                 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;
         phys_addr_t 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(__pa(r2o) | _ASCE_TYPE_REGION2, raddr);
         r3t = *r2e & _REGION_ENTRY_ORIGIN;
         *r2e = _REGION2_ENTRY_EMPTY;
         __gmap_unshadow_r3t(sg, raddr, __va(r3t));
         /* Free region 3 table */
         page = phys_to_page(r3t);
         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)
 {
         phys_addr_t 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 = r2t[i] & _REGION_ENTRY_ORIGIN;
                 r2t[i] = _REGION2_ENTRY_EMPTY;
                 __gmap_unshadow_r3t(sg, raddr, __va(r3t));
                 /* Free region 3 table */
                 page = phys_to_page(r3t);
                 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;
         struct page *page;
         phys_addr_t r2t;
 
         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(__pa(r1o) | _ASCE_TYPE_REGION1, raddr);
         r2t = *r1e & _REGION_ENTRY_ORIGIN;
         *r1e = _REGION1_ENTRY_EMPTY;
         __gmap_unshadow_r2t(sg, raddr, __va(r2t));
         /* Free region 2 table */
         page = phys_to_page(r2t);
         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;
         struct page *page;
         phys_addr_t r2t;
         int i;
 
         BUG_ON(!gmap_is_shadow(sg));
         asce = __pa(r1t) | _ASCE_TYPE_REGION1;
         for (i = 0; i < _CRST_ENTRIES; i++, raddr += _REGION1_SIZE) {
                 if (!(r1t[i] & _REGION_ENTRY_ORIGIN))
                         continue;
                 r2t = r1t[i] & _REGION_ENTRY_ORIGIN;
                 __gmap_unshadow_r2t(sg, raddr, __va(r2t));
                 /* Clear entry and flush translation r1t -> r2t */
                 gmap_idte_one(asce, raddr);
                 r1t[i] = _REGION1_ENTRY_EMPTY;
                 /* Free region 2 table */
                 page = phys_to_page(r2t);
                 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 = __va(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->private = parent->private;
         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 descendants.
  *
  * 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 *table;
         phys_addr_t s_r2t;
         struct page *page;
         int rc;
 
         BUG_ON(!gmap_is_shadow(sg));
         /* Allocate a shadow region second table */
         page = gmap_alloc_crst();
         if (!page)
                 return -ENOMEM;
         page->index = r2t & _REGION_ENTRY_ORIGIN;
         if (fake)
                 page->index |= GMAP_SHADOW_FAKE_TABLE;
         s_r2t = 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(__va(s_r2t), _REGION2_ENTRY_EMPTY);
         /* mark as invalid as long as the parent table is not protected */
         *table = 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) != 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 *table;
         phys_addr_t s_r3t;
         struct page *page;
         int rc;
 
         BUG_ON(!gmap_is_shadow(sg));
         /* Allocate a shadow region second table */
         page = gmap_alloc_crst();
         if (!page)
                 return -ENOMEM;
         page->index = r3t & _REGION_ENTRY_ORIGIN;
         if (fake)
                 page->index |= GMAP_SHADOW_FAKE_TABLE;
         s_r3t = 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(__va(s_r3t), _REGION3_ENTRY_EMPTY);
         /* mark as invalid as long as the parent table is not protected */
         *table = 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) != 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 *table;
         phys_addr_t s_sgt;
         struct page *page;
         int rc;
 
         BUG_ON(!gmap_is_shadow(sg) || (sgt & _REGION3_ENTRY_LARGE));
         /* Allocate a shadow segment table */
         page = gmap_alloc_crst();
         if (!page)
                 return -ENOMEM;
         page->index = sgt & _REGION_ENTRY_ORIGIN;
         if (fake)
                 page->index |= GMAP_SHADOW_FAKE_TABLE;
         s_sgt = 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(__va(s_sgt), _SEGMENT_ENTRY_EMPTY);
         /* mark as invalid as long as the parent table is not protected */
         *table = 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) != 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 *table;
         struct ptdesc *ptdesc;
         phys_addr_t s_pgt;
         int rc;
 
         BUG_ON(!gmap_is_shadow(sg) || (pgt & _SEGMENT_ENTRY_LARGE));
         /* Allocate a shadow page table */
         ptdesc = page_table_alloc_pgste(sg->mm);
         if (!ptdesc)
                 return -ENOMEM;
         ptdesc->pt_index = pgt & _SEGMENT_ENTRY_ORIGIN;
         if (fake)
                 ptdesc->pt_index |= GMAP_SHADOW_FAKE_TABLE;
         s_pgt = page_to_phys(ptdesc_page(ptdesc));
         /* 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(&ptdesc->pt_list, &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) != 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(ptdesc);
         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(sptep, 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(sptep, 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_leaf(*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);
                         pte_unmap_unlock(ptep, 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,
         .walk_lock      = PGWALK_WRLOCK_VERIFY,
 };
 
 static inline void thp_split_mm(struct mm_struct *mm)
 {
         struct vm_area_struct *vma;
         VMA_ITERATOR(vmi, mm, 0);
 
         for_each_vma(vmi, vma) {
                 vm_flags_mod(vma, VM_NOHUGEPAGE, VM_HUGEPAGE);
                 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 */
 
 /*
  * 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);
         mmap_write_unlock(mm);
         return 0;
 }
 EXPORT_SYMBOL_GPL(s390_enable_sie);
 
 static int find_zeropage_pte_entry(pte_t *pte, unsigned long addr,
                                    unsigned long end, struct mm_walk *walk)
 {
         unsigned long *found_addr = walk->private;
 
         /* Return 1 of the page is a zeropage. */
         if (is_zero_pfn(pte_pfn(*pte))) {
                 /*
                  * Shared zeropage in e.g., a FS DAX mapping? We cannot do the
                  * right thing and likely don't care: FAULT_FLAG_UNSHARE
                  * currently only works in COW mappings, which is also where
                  * mm_forbids_zeropage() is checked.
                  */
                 if (!is_cow_mapping(walk->vma->vm_flags))
                         return -EFAULT;
 
                 *found_addr = addr;
                 return 1;
         }
         return 0;
 }
 
 static const struct mm_walk_ops find_zeropage_ops = {
         .pte_entry      = find_zeropage_pte_entry,
         .walk_lock      = PGWALK_WRLOCK,
 };
 
 /*
  * Unshare all shared zeropages, replacing them by anonymous pages. Note that
  * we cannot simply zap all shared zeropages, because this could later
  * trigger unexpected userfaultfd missing events.
  *
  * This must be called after mm->context.allow_cow_sharing was
  * set to 0, to avoid future mappings of shared zeropages.
  *
  * mm contracts with s390, that even if mm were to remove a page table,
  * and racing with walk_page_range_vma() calling pte_offset_map_lock()
  * would fail, it will never insert a page table containing empty zero
  * pages once mm_forbids_zeropage(mm) i.e.
  * mm->context.allow_cow_sharing is set to 0.
  */
 static int __s390_unshare_zeropages(struct mm_struct *mm)
 {
         struct vm_area_struct *vma;
         VMA_ITERATOR(vmi, mm, 0);
         unsigned long addr;
         vm_fault_t fault;
         int rc;
 
         for_each_vma(vmi, vma) {
                 /*
                  * We could only look at COW mappings, but it's more future
                  * proof to catch unexpected zeropages in other mappings and
                  * fail.
                  */
                 if ((vma->vm_flags & VM_PFNMAP) || is_vm_hugetlb_page(vma))
                         continue;
                 addr = vma->vm_start;
 
 retry:
                 rc = walk_page_range_vma(vma, addr, vma->vm_end,
                                          &find_zeropage_ops, &addr);
                 if (rc < 0)
                         return rc;
                 else if (!rc)
                         continue;
 
                 /* addr was updated by find_zeropage_pte_entry() */
                 fault = handle_mm_fault(vma, addr,
                                         FAULT_FLAG_UNSHARE | FAULT_FLAG_REMOTE,
                                         NULL);
                 if (fault & VM_FAULT_OOM)
                         return -ENOMEM;
                 /*
                  * See break_ksm(): even after handle_mm_fault() returned 0, we
                  * must start the lookup from the current address, because
                  * handle_mm_fault() may back out if there's any difficulty.
                  *
                  * VM_FAULT_SIGBUS and VM_FAULT_SIGSEGV are unexpected but
                  * maybe they could trigger in the future on concurrent
                  * truncation. In that case, the shared zeropage would be gone
                  * and we can simply retry and make progress.
                  */
                 cond_resched();
                 goto retry;
         }
 
         return 0;
 }
 
 static int __s390_disable_cow_sharing(struct mm_struct *mm)
 {
         int rc;
 
         if (!mm->context.allow_cow_sharing)
                 return 0;
 
         mm->context.allow_cow_sharing = 0;
 
         /* Replace all shared zeropages by anonymous pages. */
         rc = __s390_unshare_zeropages(mm);
         /*
          * Make sure to disable KSM (if enabled for the whole process or
          * individual VMAs). Note that nothing currently hinders user space
          * from re-enabling it.
          */
         if (!rc)
                 rc = ksm_disable(mm);
         if (rc)
                 mm->context.allow_cow_sharing = 1;
         return rc;
 }
 
 /*
  * Disable most COW-sharing of memory pages for the whole process:
  * (1) Disable KSM and unmerge/unshare any KSM pages.
  * (2) Disallow shared zeropages and unshare any zerpages that are mapped.
  *
  * Not that we currently don't bother with COW-shared pages that are shared
  * with parent/child processes due to fork().
  */
 int s390_disable_cow_sharing(void)
 {
         int rc;
 
         mmap_write_lock(current->mm);
         rc = __s390_disable_cow_sharing(current->mm);
         mmap_write_unlock(current->mm);
         return rc;
 }
 EXPORT_SYMBOL_GPL(s390_disable_cow_sharing);
 
 /*
  * 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 folio *folio = page_folio(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;
         __storage_key_init_range(start, end);
         set_bit(PG_arch_1, &folio->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,
         .walk_lock              = PGWALK_WRLOCK,
 };
 
 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 = __s390_disable_cow_sharing(mm);
         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,
         .walk_lock              = PGWALK_WRLOCK,
 };
 
 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,
         .walk_lock = PGWALK_RDLOCK,
 };
 
 /*
  * 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)
 {
         struct folio *folio;
         unsigned long i;
 
         for (i = 0; i < count; i++) {
                 folio = pfn_folio(pfns[i]);
                 /* we always have an extra reference */
                 uv_destroy_folio(folio);
                 /* get rid of the extra reference */
                 folio_put(folio);
                 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 ASCE is a SEGMENT type then this function will return -EINVAL,
  * otherwise the pointers in the host_to_guest radix tree will keep pointing
  * to the wrong pages, causing use-after-free and memory corruption.
  * 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);
 
         /* Replacing segment type ASCEs would cause serious issues */
         if ((gmap->asce & _ASCE_TYPE_MASK) == _ASCE_TYPE_SEGMENT)
                 return -EINVAL;
 
         page = gmap_alloc_crst();
         if (!page)
                 return -ENOMEM;
         page->index = 0;
         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);
 

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