KVM: MMU: Make flooding detection work when guest page faults are bypassed
[safe/jmp/linux-2.6] / drivers / kvm / paging_tmpl.h
index 03c474a..be0f852 100644 (file)
@@ -31,7 +31,7 @@
        #define PT_INDEX(addr, level) PT64_INDEX(addr, level)
        #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
        #define PT_LEVEL_MASK(level) PT64_LEVEL_MASK(level)
-       #define PT_PTE_COPY_MASK PT64_PTE_COPY_MASK
+       #define PT_LEVEL_BITS PT64_LEVEL_BITS
        #ifdef CONFIG_X86_64
        #define PT_MAX_FULL_LEVELS 4
        #else
@@ -46,7 +46,7 @@
        #define PT_INDEX(addr, level) PT32_INDEX(addr, level)
        #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
        #define PT_LEVEL_MASK(level) PT32_LEVEL_MASK(level)
-       #define PT_PTE_COPY_MASK PT32_PTE_COPY_MASK
+       #define PT_LEVEL_BITS PT32_LEVEL_BITS
        #define PT_MAX_FULL_LEVELS 2
 #else
        #error Invalid PTTYPE value
@@ -60,16 +60,21 @@ struct guest_walker {
        int level;
        gfn_t table_gfn[PT_MAX_FULL_LEVELS];
        pt_element_t *table;
+       pt_element_t pte;
        pt_element_t *ptep;
+       struct page *page;
+       int index;
        pt_element_t inherited_ar;
        gfn_t gfn;
+       u32 error_code;
 };
 
 /*
  * Fetch a guest pte for a guest virtual address
  */
-static void FNAME(walk_addr)(struct guest_walker *walker,
-                            struct kvm_vcpu *vcpu, gva_t addr)
+static int FNAME(walk_addr)(struct guest_walker *walker,
+                           struct kvm_vcpu *vcpu, gva_t addr,
+                           int write_fault, int user_fault, int fetch_fault)
 {
        hpa_t hpa;
        struct kvm_memory_slot *slot;
@@ -80,13 +85,16 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
        pgprintk("%s: addr %lx\n", __FUNCTION__, addr);
        walker->level = vcpu->mmu.root_level;
        walker->table = NULL;
+       walker->page = NULL;
+       walker->ptep = NULL;
        root = vcpu->cr3;
 #if PTTYPE == 64
        if (!is_long_mode(vcpu)) {
                walker->ptep = &vcpu->pdptrs[(addr >> 30) & 3];
                root = *walker->ptep;
+               walker->pte = root;
                if (!(root & PT_PRESENT_MASK))
-                       return;
+                       goto not_present;
                --walker->level;
        }
 #endif
@@ -96,10 +104,11 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
                 walker->level - 1, table_gfn);
        slot = gfn_to_memslot(vcpu->kvm, table_gfn);
        hpa = safe_gpa_to_hpa(vcpu, root & PT64_BASE_ADDR_MASK);
-       walker->table = kmap_atomic(pfn_to_page(hpa >> PAGE_SHIFT), KM_USER0);
+       walker->page = pfn_to_page(hpa >> PAGE_SHIFT);
+       walker->table = kmap_atomic(walker->page, KM_USER0);
 
        ASSERT((!is_long_mode(vcpu) && is_pae(vcpu)) ||
-              (vcpu->cr3 & ~(PAGE_MASK | CR3_FLAGS_MASK)) == 0);
+              (vcpu->cr3 & CR3_NONPAE_RESERVED_BITS) == 0);
 
        walker->inherited_ar = PT_USER_MASK | PT_WRITABLE_MASK;
 
@@ -108,14 +117,29 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
                hpa_t paddr;
 
                ptep = &walker->table[index];
+               walker->index = index;
                ASSERT(((unsigned long)walker->table & PAGE_MASK) ==
                       ((unsigned long)ptep & PAGE_MASK));
 
-               if (is_present_pte(*ptep) && !(*ptep &  PT_ACCESSED_MASK))
-                       *ptep |= PT_ACCESSED_MASK;
-
                if (!is_present_pte(*ptep))
-                       break;
+                       goto not_present;
+
+               if (write_fault && !is_writeble_pte(*ptep))
+                       if (user_fault || is_write_protection(vcpu))
+                               goto access_error;
+
+               if (user_fault && !(*ptep & PT_USER_MASK))
+                       goto access_error;
+
+#if PTTYPE == 64
+               if (fetch_fault && is_nx(vcpu) && (*ptep & PT64_NX_MASK))
+                       goto access_error;
+#endif
+
+               if (!(*ptep & PT_ACCESSED_MASK)) {
+                       mark_page_dirty(vcpu->kvm, table_gfn);
+                       *ptep |= PT_ACCESSED_MASK;
+               }
 
                if (walker->level == PT_PAGE_TABLE_LEVEL) {
                        walker->gfn = (*ptep & PT_BASE_ADDR_MASK)
@@ -132,66 +156,211 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
                        break;
                }
 
-               if (walker->level != 3 || is_long_mode(vcpu))
-                       walker->inherited_ar &= walker->table[index];
+               walker->inherited_ar &= walker->table[index];
                table_gfn = (*ptep & PT_BASE_ADDR_MASK) >> PAGE_SHIFT;
-               paddr = safe_gpa_to_hpa(vcpu, *ptep & PT_BASE_ADDR_MASK);
                kunmap_atomic(walker->table, KM_USER0);
-               walker->table = kmap_atomic(pfn_to_page(paddr >> PAGE_SHIFT),
-                                           KM_USER0);
+               paddr = safe_gpa_to_hpa(vcpu, table_gfn << PAGE_SHIFT);
+               walker->page = pfn_to_page(paddr >> PAGE_SHIFT);
+               walker->table = kmap_atomic(walker->page, KM_USER0);
                --walker->level;
                walker->table_gfn[walker->level - 1 ] = table_gfn;
                pgprintk("%s: table_gfn[%d] %lx\n", __FUNCTION__,
                         walker->level - 1, table_gfn);
        }
-       walker->ptep = ptep;
+       walker->pte = *ptep;
+       if (walker->page)
+               walker->ptep = NULL;
+       if (walker->table)
+               kunmap_atomic(walker->table, KM_USER0);
        pgprintk("%s: pte %llx\n", __FUNCTION__, (u64)*ptep);
-}
+       return 1;
 
-static void FNAME(release_walker)(struct guest_walker *walker)
-{
+not_present:
+       walker->error_code = 0;
+       goto err;
+
+access_error:
+       walker->error_code = PFERR_PRESENT_MASK;
+
+err:
+       if (write_fault)
+               walker->error_code |= PFERR_WRITE_MASK;
+       if (user_fault)
+               walker->error_code |= PFERR_USER_MASK;
+       if (fetch_fault)
+               walker->error_code |= PFERR_FETCH_MASK;
        if (walker->table)
                kunmap_atomic(walker->table, KM_USER0);
+       return 0;
 }
 
-static void FNAME(set_pte)(struct kvm_vcpu *vcpu, u64 guest_pte,
-                          u64 *shadow_pte, u64 access_bits, gfn_t gfn)
+static void FNAME(mark_pagetable_dirty)(struct kvm *kvm,
+                                       struct guest_walker *walker)
 {
-       ASSERT(*shadow_pte == 0);
-       access_bits &= guest_pte;
-       *shadow_pte = (guest_pte & PT_PTE_COPY_MASK);
-       set_pte_common(vcpu, shadow_pte, guest_pte & PT_BASE_ADDR_MASK,
-                      guest_pte & PT_DIRTY_MASK, access_bits, gfn);
+       mark_page_dirty(kvm, walker->table_gfn[walker->level - 1]);
 }
 
-static void FNAME(set_pde)(struct kvm_vcpu *vcpu, u64 guest_pde,
-                          u64 *shadow_pte, u64 access_bits, gfn_t gfn)
+static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
+                                 u64 *shadow_pte,
+                                 gpa_t gaddr,
+                                 pt_element_t gpte,
+                                 u64 access_bits,
+                                 int user_fault,
+                                 int write_fault,
+                                 int *ptwrite,
+                                 struct guest_walker *walker,
+                                 gfn_t gfn)
+{
+       hpa_t paddr;
+       int dirty = gpte & PT_DIRTY_MASK;
+       u64 spte;
+       int was_rmapped = is_rmap_pte(*shadow_pte);
+
+       pgprintk("%s: spte %llx gpte %llx access %llx write_fault %d"
+                " user_fault %d gfn %lx\n",
+                __FUNCTION__, *shadow_pte, (u64)gpte, access_bits,
+                write_fault, user_fault, gfn);
+
+       if (write_fault && !dirty) {
+               pt_element_t *guest_ent, *tmp = NULL;
+
+               if (walker->ptep)
+                       guest_ent = walker->ptep;
+               else {
+                       tmp = kmap_atomic(walker->page, KM_USER0);
+                       guest_ent = &tmp[walker->index];
+               }
+
+               *guest_ent |= PT_DIRTY_MASK;
+               if (!walker->ptep)
+                       kunmap_atomic(tmp, KM_USER0);
+               dirty = 1;
+               FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);
+       }
+
+       /*
+        * We don't set the accessed bit, since we sometimes want to see
+        * whether the guest actually used the pte (in order to detect
+        * demand paging).
+        */
+       spte = PT_PRESENT_MASK | PT_DIRTY_MASK;
+       spte |= gpte & PT64_NX_MASK;
+       if (!dirty)
+               access_bits &= ~PT_WRITABLE_MASK;
+
+       paddr = gpa_to_hpa(vcpu, gaddr & PT64_BASE_ADDR_MASK);
+
+       spte |= PT_PRESENT_MASK;
+       if (access_bits & PT_USER_MASK)
+               spte |= PT_USER_MASK;
+
+       if (is_error_hpa(paddr)) {
+               set_shadow_pte(shadow_pte,
+                              shadow_trap_nonpresent_pte | PT_SHADOW_IO_MARK);
+               return;
+       }
+
+       spte |= paddr;
+
+       if ((access_bits & PT_WRITABLE_MASK)
+           || (write_fault && !is_write_protection(vcpu) && !user_fault)) {
+               struct kvm_mmu_page *shadow;
+
+               spte |= PT_WRITABLE_MASK;
+               if (user_fault) {
+                       mmu_unshadow(vcpu, gfn);
+                       goto unshadowed;
+               }
+
+               shadow = kvm_mmu_lookup_page(vcpu, gfn);
+               if (shadow) {
+                       pgprintk("%s: found shadow page for %lx, marking ro\n",
+                                __FUNCTION__, gfn);
+                       access_bits &= ~PT_WRITABLE_MASK;
+                       if (is_writeble_pte(spte)) {
+                               spte &= ~PT_WRITABLE_MASK;
+                               kvm_x86_ops->tlb_flush(vcpu);
+                       }
+                       if (write_fault)
+                               *ptwrite = 1;
+               }
+       }
+
+unshadowed:
+
+       if (access_bits & PT_WRITABLE_MASK)
+               mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT);
+
+       pgprintk("%s: setting spte %llx\n", __FUNCTION__, spte);
+       set_shadow_pte(shadow_pte, spte);
+       page_header_update_slot(vcpu->kvm, shadow_pte, gaddr);
+       if (!was_rmapped)
+               rmap_add(vcpu, shadow_pte);
+       if (!ptwrite || !*ptwrite)
+               vcpu->last_pte_updated = shadow_pte;
+}
+
+static void FNAME(set_pte)(struct kvm_vcpu *vcpu, pt_element_t gpte,
+                          u64 *shadow_pte, u64 access_bits,
+                          int user_fault, int write_fault, int *ptwrite,
+                          struct guest_walker *walker, gfn_t gfn)
+{
+       access_bits &= gpte;
+       FNAME(set_pte_common)(vcpu, shadow_pte, gpte & PT_BASE_ADDR_MASK,
+                             gpte, access_bits, user_fault, write_fault,
+                             ptwrite, walker, gfn);
+}
+
+static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
+                             u64 *spte, const void *pte, int bytes,
+                             int offset_in_pte)
+{
+       pt_element_t gpte;
+
+       gpte = *(const pt_element_t *)pte;
+       if (~gpte & (PT_PRESENT_MASK | PT_ACCESSED_MASK)) {
+               if (!offset_in_pte && !is_present_pte(gpte))
+                       set_shadow_pte(spte, shadow_notrap_nonpresent_pte);
+               return;
+       }
+       if (bytes < sizeof(pt_element_t))
+               return;
+       pgprintk("%s: gpte %llx spte %p\n", __FUNCTION__, (u64)gpte, spte);
+       FNAME(set_pte)(vcpu, gpte, spte, PT_USER_MASK | PT_WRITABLE_MASK, 0,
+                      0, NULL, NULL,
+                      (gpte & PT_BASE_ADDR_MASK) >> PAGE_SHIFT);
+}
+
+static void FNAME(set_pde)(struct kvm_vcpu *vcpu, pt_element_t gpde,
+                          u64 *shadow_pte, u64 access_bits,
+                          int user_fault, int write_fault, int *ptwrite,
+                          struct guest_walker *walker, gfn_t gfn)
 {
        gpa_t gaddr;
 
-       ASSERT(*shadow_pte == 0);
-       access_bits &= guest_pde;
+       access_bits &= gpde;
        gaddr = (gpa_t)gfn << PAGE_SHIFT;
        if (PTTYPE == 32 && is_cpuid_PSE36())
-               gaddr |= (guest_pde & PT32_DIR_PSE36_MASK) <<
+               gaddr |= (gpde & PT32_DIR_PSE36_MASK) <<
                        (32 - PT32_DIR_PSE36_SHIFT);
-       *shadow_pte = guest_pde & PT_PTE_COPY_MASK;
-       set_pte_common(vcpu, shadow_pte, gaddr,
-                      guest_pde & PT_DIRTY_MASK, access_bits, gfn);
+       FNAME(set_pte_common)(vcpu, shadow_pte, gaddr,
+                             gpde, access_bits, user_fault, write_fault,
+                             ptwrite, walker, gfn);
 }
 
 /*
  * Fetch a shadow pte for a specific level in the paging hierarchy.
  */
 static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
-                             struct guest_walker *walker)
+                        struct guest_walker *walker,
+                        int user_fault, int write_fault, int *ptwrite)
 {
        hpa_t shadow_addr;
        int level;
+       u64 *shadow_ent;
        u64 *prev_shadow_ent = NULL;
-       pt_element_t *guest_ent = walker->ptep;
 
-       if (!is_present_pte(*guest_ent))
+       if (!is_present_pte(walker->pte))
                return NULL;
 
        shadow_addr = vcpu->mmu.root_hpa;
@@ -204,117 +373,59 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
 
        for (; ; level--) {
                u32 index = SHADOW_PT_INDEX(addr, level);
-               u64 *shadow_ent = ((u64 *)__va(shadow_addr)) + index;
                struct kvm_mmu_page *shadow_page;
                u64 shadow_pte;
                int metaphysical;
                gfn_t table_gfn;
+               unsigned hugepage_access = 0;
 
-               if (is_present_pte(*shadow_ent) || is_io_pte(*shadow_ent)) {
+               shadow_ent = ((u64 *)__va(shadow_addr)) + index;
+               if (is_shadow_present_pte(*shadow_ent)) {
                        if (level == PT_PAGE_TABLE_LEVEL)
-                               return shadow_ent;
+                               break;
                        shadow_addr = *shadow_ent & PT64_BASE_ADDR_MASK;
                        prev_shadow_ent = shadow_ent;
                        continue;
                }
 
-               if (level == PT_PAGE_TABLE_LEVEL) {
-
-                       if (walker->level == PT_DIRECTORY_LEVEL) {
-                               if (prev_shadow_ent)
-                                       *prev_shadow_ent |= PT_SHADOW_PS_MARK;
-                               FNAME(set_pde)(vcpu, *guest_ent, shadow_ent,
-                                              walker->inherited_ar,
-                                              walker->gfn);
-                       } else {
-                               ASSERT(walker->level == PT_PAGE_TABLE_LEVEL);
-                               FNAME(set_pte)(vcpu, *guest_ent, shadow_ent,
-                                              walker->inherited_ar,
-                                              walker->gfn);
-                       }
-                       return shadow_ent;
-               }
+               if (level == PT_PAGE_TABLE_LEVEL)
+                       break;
 
                if (level - 1 == PT_PAGE_TABLE_LEVEL
                    && walker->level == PT_DIRECTORY_LEVEL) {
                        metaphysical = 1;
-                       table_gfn = (*guest_ent & PT_BASE_ADDR_MASK)
+                       hugepage_access = walker->pte;
+                       hugepage_access &= PT_USER_MASK | PT_WRITABLE_MASK;
+                       if (walker->pte & PT64_NX_MASK)
+                               hugepage_access |= (1 << 2);
+                       hugepage_access >>= PT_WRITABLE_SHIFT;
+                       table_gfn = (walker->pte & PT_BASE_ADDR_MASK)
                                >> PAGE_SHIFT;
                } else {
                        metaphysical = 0;
                        table_gfn = walker->table_gfn[level - 2];
                }
                shadow_page = kvm_mmu_get_page(vcpu, table_gfn, addr, level-1,
-                                              metaphysical, shadow_ent);
-               shadow_addr = shadow_page->page_hpa;
+                                              metaphysical, hugepage_access,
+                                              shadow_ent);
+               shadow_addr = __pa(shadow_page->spt);
                shadow_pte = shadow_addr | PT_PRESENT_MASK | PT_ACCESSED_MASK
                        | PT_WRITABLE_MASK | PT_USER_MASK;
                *shadow_ent = shadow_pte;
                prev_shadow_ent = shadow_ent;
        }
-}
 
-/*
- * The guest faulted for write.  We need to
- *
- * - check write permissions
- * - update the guest pte dirty bit
- * - update our own dirty page tracking structures
- */
-static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu,
-                              u64 *shadow_ent,
-                              struct guest_walker *walker,
-                              gva_t addr,
-                              int user,
-                              int *write_pt)
-{
-       pt_element_t *guest_ent;
-       int writable_shadow;
-       gfn_t gfn;
-
-       if (is_writeble_pte(*shadow_ent))
-               return 0;
-
-       writable_shadow = *shadow_ent & PT_SHADOW_WRITABLE_MASK;
-       if (user) {
-               /*
-                * User mode access.  Fail if it's a kernel page or a read-only
-                * page.
-                */
-               if (!(*shadow_ent & PT_SHADOW_USER_MASK) || !writable_shadow)
-                       return 0;
-               ASSERT(*shadow_ent & PT_USER_MASK);
-       } else
-               /*
-                * Kernel mode access.  Fail if it's a read-only page and
-                * supervisor write protection is enabled.
-                */
-               if (!writable_shadow) {
-                       if (is_write_protection(vcpu))
-                               return 0;
-                       *shadow_ent &= ~PT_USER_MASK;
-               }
-
-       guest_ent = walker->ptep;
-
-       if (!is_present_pte(*guest_ent)) {
-               *shadow_ent = 0;
-               return 0;
-       }
-
-       gfn = walker->gfn;
-       if (kvm_mmu_lookup_page(vcpu, gfn)) {
-               pgprintk("%s: found shadow page for %lx, marking ro\n",
-                        __FUNCTION__, gfn);
-               *write_pt = 1;
-               return 0;
+       if (walker->level == PT_DIRECTORY_LEVEL) {
+               FNAME(set_pde)(vcpu, walker->pte, shadow_ent,
+                              walker->inherited_ar, user_fault, write_fault,
+                              ptwrite, walker, walker->gfn);
+       } else {
+               ASSERT(walker->level == PT_PAGE_TABLE_LEVEL);
+               FNAME(set_pte)(vcpu, walker->pte, shadow_ent,
+                              walker->inherited_ar, user_fault, write_fault,
+                              ptwrite, walker, walker->gfn);
        }
-       mark_page_dirty(vcpu->kvm, gfn);
-       *shadow_ent |= PT_WRITABLE_MASK;
-       *guest_ent |= PT_DIRTY_MASK;
-       rmap_add(vcpu->kvm, shadow_ent);
-
-       return 1;
+       return shadow_ent;
 }
 
 /*
@@ -328,74 +439,59 @@ static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu,
  *   - normal guest page fault due to the guest pte marked not present, not
  *     writable, or not executable
  *
- *  Returns: 1 if we need to emulate the instruction, 0 otherwise
+ *  Returns: 1 if we need to emulate the instruction, 0 otherwise, or
+ *           a negative value on error.
  */
 static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
                               u32 error_code)
 {
        int write_fault = error_code & PFERR_WRITE_MASK;
-       int pte_present = error_code & PFERR_PRESENT_MASK;
        int user_fault = error_code & PFERR_USER_MASK;
+       int fetch_fault = error_code & PFERR_FETCH_MASK;
        struct guest_walker walker;
        u64 *shadow_pte;
-       int fixed;
        int write_pt = 0;
+       int r;
 
        pgprintk("%s: addr %lx err %x\n", __FUNCTION__, addr, error_code);
+       kvm_mmu_audit(vcpu, "pre page fault");
+
+       r = mmu_topup_memory_caches(vcpu);
+       if (r)
+               return r;
+
        /*
         * Look up the shadow pte for the faulting address.
         */
-       FNAME(walk_addr)(&walker, vcpu, addr);
-       shadow_pte = FNAME(fetch)(vcpu, addr, &walker);
+       r = FNAME(walk_addr)(&walker, vcpu, addr, write_fault, user_fault,
+                            fetch_fault);
 
        /*
         * The page is not mapped by the guest.  Let the guest handle it.
         */
-       if (!shadow_pte) {
-               pgprintk("%s: not mapped\n", __FUNCTION__);
-               inject_page_fault(vcpu, addr, error_code);
-               FNAME(release_walker)(&walker);
+       if (!r) {
+               pgprintk("%s: guest page fault\n", __FUNCTION__);
+               inject_page_fault(vcpu, addr, walker.error_code);
+               vcpu->last_pt_write_count = 0; /* reset fork detector */
                return 0;
        }
 
-       pgprintk("%s: shadow pte %p %llx\n", __FUNCTION__,
-                shadow_pte, *shadow_pte);
-
-       /*
-        * Update the shadow pte.
-        */
-       if (write_fault)
-               fixed = FNAME(fix_write_pf)(vcpu, shadow_pte, &walker, addr,
-                                           user_fault, &write_pt);
-       else
-               fixed = fix_read_pf(shadow_pte);
+       shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
+                                 &write_pt);
+       pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__,
+                shadow_pte, *shadow_pte, write_pt);
 
-       pgprintk("%s: updated shadow pte %p %llx\n", __FUNCTION__,
-                shadow_pte, *shadow_pte);
-
-       FNAME(release_walker)(&walker);
+       if (!write_pt)
+               vcpu->last_pt_write_count = 0; /* reset fork detector */
 
        /*
         * mmio: emulate if accessible, otherwise its a guest fault.
         */
-       if (is_io_pte(*shadow_pte)) {
-               if (may_access(*shadow_pte, write_fault, user_fault))
-                       return 1;
-               pgprintk("%s: io work, no access\n", __FUNCTION__);
-               inject_page_fault(vcpu, addr,
-                                 error_code | PFERR_PRESENT_MASK);
-               return 0;
-       }
+       if (is_io_pte(*shadow_pte))
+               return 1;
 
-       /*
-        * pte not present, guest page fault.
-        */
-       if (pte_present && !fixed && !write_pt) {
-               inject_page_fault(vcpu, addr, error_code);
-               return 0;
-       }
-
-       ++kvm_stat.pf_fixed;
+       ++vcpu->stat.pf_fixed;
+       kvm_mmu_audit(vcpu, "post page fault (fixed)");
 
        return write_pt;
 }
@@ -403,32 +499,37 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
 static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
 {
        struct guest_walker walker;
-       pt_element_t guest_pte;
-       gpa_t gpa;
+       gpa_t gpa = UNMAPPED_GVA;
+       int r;
 
-       FNAME(walk_addr)(&walker, vcpu, vaddr);
-       guest_pte = *walker.ptep;
-       FNAME(release_walker)(&walker);
+       r = FNAME(walk_addr)(&walker, vcpu, vaddr, 0, 0, 0);
 
-       if (!is_present_pte(guest_pte))
-               return UNMAPPED_GVA;
+       if (r) {
+               gpa = (gpa_t)walker.gfn << PAGE_SHIFT;
+               gpa |= vaddr & ~PAGE_MASK;
+       }
 
-       if (walker.level == PT_DIRECTORY_LEVEL) {
-               ASSERT((guest_pte & PT_PAGE_SIZE_MASK));
-               ASSERT(PTTYPE == 64 || is_pse(vcpu));
+       return gpa;
+}
 
-               gpa = (guest_pte & PT_DIR_BASE_ADDR_MASK) | (vaddr &
-                       (PT_LEVEL_MASK(PT_PAGE_TABLE_LEVEL) | ~PAGE_MASK));
+static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
+                                struct kvm_mmu_page *sp)
+{
+       int i;
+       pt_element_t *gpt;
 
-               if (PTTYPE == 32 && is_cpuid_PSE36())
-                       gpa |= (guest_pte & PT32_DIR_PSE36_MASK) <<
-                                       (32 - PT32_DIR_PSE36_SHIFT);
-       } else {
-               gpa = (guest_pte & PT_BASE_ADDR_MASK);
-               gpa |= (vaddr & ~PAGE_MASK);
+       if (sp->role.metaphysical || PTTYPE == 32) {
+               nonpaging_prefetch_page(vcpu, sp);
+               return;
        }
 
-       return gpa;
+       gpt = kmap_atomic(gfn_to_page(vcpu->kvm, sp->gfn), KM_USER0);
+       for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
+               if (is_present_pte(gpt[i]))
+                       sp->spt[i] = shadow_trap_nonpresent_pte;
+               else
+                       sp->spt[i] = shadow_notrap_nonpresent_pte;
+       kunmap_atomic(gpt, KM_USER0);
 }
 
 #undef pt_element_t
@@ -438,7 +539,6 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
 #undef PT_INDEX
 #undef SHADOW_PT_INDEX
 #undef PT_LEVEL_MASK
-#undef PT_PTE_COPY_MASK
-#undef PT_NON_PTE_COPY_MASK
 #undef PT_DIR_BASE_ADDR_MASK
+#undef PT_LEVEL_BITS
 #undef PT_MAX_FULL_LEVELS