KVM: MMU: delay flush all tlbs on sync_page path
[linux-2.6.git] / arch / x86 / kvm / paging_tmpl.h
index 8cb85f9..2b3d66c 100644 (file)
@@ -7,7 +7,7 @@
  * MMU support
  *
  * Copyright (C) 2006 Qumranet, Inc.
- * Copyright 2010 Red Hat, Inc. and/or its affilates.
+ * Copyright 2010 Red Hat, Inc. and/or its affiliates.
  *
  * Authors:
  *   Yaniv Kamay  <yaniv@qumranet.com>
@@ -67,6 +67,7 @@ struct guest_walker {
        int level;
        gfn_t table_gfn[PT_MAX_FULL_LEVELS];
        pt_element_t ptes[PT_MAX_FULL_LEVELS];
+       pt_element_t prefetch_ptes[PTE_PREFETCH_NUM];
        gpa_t pte_gpa[PT_MAX_FULL_LEVELS];
        unsigned pt_access;
        unsigned pte_access;
@@ -104,7 +105,7 @@ static unsigned FNAME(gpte_access)(struct kvm_vcpu *vcpu, pt_element_t gpte)
 
        access = (gpte & (PT_WRITABLE_MASK | PT_USER_MASK)) | ACC_EXEC_MASK;
 #if PTTYPE == 64
-       if (is_nx(vcpu))
+       if (vcpu->arch.mmu.nx)
                access &= ~(gpte >> PT64_NX_SHIFT);
 #endif
        return access;
@@ -113,26 +114,32 @@ static unsigned FNAME(gpte_access)(struct kvm_vcpu *vcpu, pt_element_t gpte)
 /*
  * Fetch a guest pte for a guest virtual address
  */
-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)
+static int FNAME(walk_addr_generic)(struct guest_walker *walker,
+                                   struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
+                                   gva_t addr, u32 access)
 {
        pt_element_t pte;
        gfn_t table_gfn;
        unsigned index, pt_access, uninitialized_var(pte_access);
        gpa_t pte_gpa;
        bool eperm, present, rsvd_fault;
+       int offset, write_fault, user_fault, fetch_fault;
+
+       write_fault = access & PFERR_WRITE_MASK;
+       user_fault = access & PFERR_USER_MASK;
+       fetch_fault = access & PFERR_FETCH_MASK;
 
        trace_kvm_mmu_pagetable_walk(addr, write_fault, user_fault,
                                     fetch_fault);
 walk:
        present = true;
        eperm = rsvd_fault = false;
-       walker->level = vcpu->arch.mmu.root_level;
-       pte = vcpu->arch.cr3;
+       walker->level = mmu->root_level;
+       pte           = mmu->get_cr3(vcpu);
+
 #if PTTYPE == 64
-       if (!is_long_mode(vcpu)) {
-               pte = kvm_pdptr_read(vcpu, (addr >> 30) & 3);
+       if (walker->level == PT32E_ROOT_LEVEL) {
+               pte = kvm_pdptr_read_mmu(vcpu, mmu, (addr >> 30) & 3);
                trace_kvm_mmu_paging_element(pte, walker->level);
                if (!is_present_gpte(pte)) {
                        present = false;
@@ -142,7 +149,7 @@ walk:
        }
 #endif
        ASSERT((!is_long_mode(vcpu) && is_pae(vcpu)) ||
-              (vcpu->arch.cr3 & CR3_NONPAE_RESERVED_BITS) == 0);
+              (mmu->get_cr3(vcpu) & CR3_NONPAE_RESERVED_BITS) == 0);
 
        pt_access = ACC_ALL;
 
@@ -150,12 +157,14 @@ walk:
                index = PT_INDEX(addr, walker->level);
 
                table_gfn = gpte_to_gfn(pte);
-               pte_gpa = gfn_to_gpa(table_gfn);
-               pte_gpa += index * sizeof(pt_element_t);
+               offset    = index * sizeof(pt_element_t);
+               pte_gpa   = gfn_to_gpa(table_gfn) + offset;
                walker->table_gfn[walker->level - 1] = table_gfn;
                walker->pte_gpa[walker->level - 1] = pte_gpa;
 
-               if (kvm_read_guest(vcpu->kvm, pte_gpa, &pte, sizeof(pte))) {
+               if (kvm_read_guest_page_mmu(vcpu, mmu, table_gfn, &pte,
+                                           offset, sizeof(pte),
+                                           PFERR_USER_MASK|PFERR_WRITE_MASK)) {
                        present = false;
                        break;
                }
@@ -167,7 +176,7 @@ walk:
                        break;
                }
 
-               if (is_rsvd_bits_set(vcpu, pte, walker->level)) {
+               if (is_rsvd_bits_set(&vcpu->arch.mmu, pte, walker->level)) {
                        rsvd_fault = true;
                        break;
                }
@@ -204,17 +213,28 @@ walk:
                                (PTTYPE == 64 || is_pse(vcpu))) ||
                    ((walker->level == PT_PDPE_LEVEL) &&
                                is_large_pte(pte) &&
-                               is_long_mode(vcpu))) {
+                               mmu->root_level == PT64_ROOT_LEVEL)) {
                        int lvl = walker->level;
+                       gpa_t real_gpa;
+                       gfn_t gfn;
+                       u32 ac;
 
-                       walker->gfn = gpte_to_gfn_lvl(pte, lvl);
-                       walker->gfn += (addr & PT_LVL_OFFSET_MASK(lvl))
-                                       >> PAGE_SHIFT;
+                       gfn = gpte_to_gfn_lvl(pte, lvl);
+                       gfn += (addr & PT_LVL_OFFSET_MASK(lvl)) >> PAGE_SHIFT;
 
                        if (PTTYPE == 32 &&
                            walker->level == PT_DIRECTORY_LEVEL &&
                            is_cpuid_PSE36())
-                               walker->gfn += pse36_gfn_delta(pte);
+                               gfn += pse36_gfn_delta(pte);
+
+                       ac = write_fault | fetch_fault | user_fault;
+
+                       real_gpa = mmu->translate_gpa(vcpu, gfn_to_gpa(gfn),
+                                                     ac);
+                       if (real_gpa == UNMAPPED_GVA)
+                               return 0;
+
+                       walker->gfn = real_gpa >> PAGE_SHIFT;
 
                        break;
                }
@@ -249,37 +269,72 @@ error:
        walker->error_code = 0;
        if (present)
                walker->error_code |= PFERR_PRESENT_MASK;
-       if (write_fault)
-               walker->error_code |= PFERR_WRITE_MASK;
-       if (user_fault)
-               walker->error_code |= PFERR_USER_MASK;
-       if (fetch_fault && is_nx(vcpu))
+
+       walker->error_code |= write_fault | user_fault;
+
+       if (fetch_fault && mmu->nx)
                walker->error_code |= PFERR_FETCH_MASK;
        if (rsvd_fault)
                walker->error_code |= PFERR_RSVD_MASK;
+
+       vcpu->arch.fault.address    = addr;
+       vcpu->arch.fault.error_code = walker->error_code;
+
        trace_kvm_mmu_walker_error(walker->error_code);
        return 0;
 }
 
+static int FNAME(walk_addr)(struct guest_walker *walker,
+                           struct kvm_vcpu *vcpu, gva_t addr, u32 access)
+{
+       return FNAME(walk_addr_generic)(walker, vcpu, &vcpu->arch.mmu, addr,
+                                       access);
+}
+
+static int FNAME(walk_addr_nested)(struct guest_walker *walker,
+                                  struct kvm_vcpu *vcpu, gva_t addr,
+                                  u32 access)
+{
+       return FNAME(walk_addr_generic)(walker, vcpu, &vcpu->arch.nested_mmu,
+                                       addr, access);
+}
+
+static bool FNAME(prefetch_invalid_gpte)(struct kvm_vcpu *vcpu,
+                                   struct kvm_mmu_page *sp, u64 *spte,
+                                   pt_element_t gpte)
+{
+       u64 nonpresent = shadow_trap_nonpresent_pte;
+
+       if (is_rsvd_bits_set(&vcpu->arch.mmu, gpte, PT_PAGE_TABLE_LEVEL))
+               goto no_present;
+
+       if (!is_present_gpte(gpte)) {
+               if (!sp->unsync)
+                       nonpresent = shadow_notrap_nonpresent_pte;
+               goto no_present;
+       }
+
+       if (!(gpte & PT_ACCESSED_MASK))
+               goto no_present;
+
+       return false;
+
+no_present:
+       drop_spte(vcpu->kvm, spte, nonpresent);
+       return true;
+}
+
 static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
                              u64 *spte, const void *pte)
 {
        pt_element_t gpte;
        unsigned pte_access;
        pfn_t pfn;
-       u64 new_spte;
 
        gpte = *(const pt_element_t *)pte;
-       if (~gpte & (PT_PRESENT_MASK | PT_ACCESSED_MASK)) {
-               if (!is_present_gpte(gpte)) {
-                       if (sp->unsync)
-                               new_spte = shadow_trap_nonpresent_pte;
-                       else
-                               new_spte = shadow_notrap_nonpresent_pte;
-                       __set_spte(spte, new_spte);
-               }
+       if (FNAME(prefetch_invalid_gpte)(vcpu, sp, spte, gpte))
                return;
-       }
+
        pgprintk("%s: gpte %llx spte %p\n", __func__, (u64)gpte, spte);
        pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
        if (gpte_to_gfn(gpte) != vcpu->arch.update_pte.gfn)
@@ -291,7 +346,7 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
                return;
        kvm_get_pfn(pfn);
        /*
-        * we call mmu_set_spte() with reset_host_protection = true beacuse that
+        * we call mmu_set_spte() with host_writable = true beacuse that
         * vcpu->arch.update_pte.pfn was fetched from get_user_pages(write = 1).
         */
        mmu_set_spte(vcpu, spte, sp->role.access, pte_access, 0, 0,
@@ -302,30 +357,93 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 static bool FNAME(gpte_changed)(struct kvm_vcpu *vcpu,
                                struct guest_walker *gw, int level)
 {
-       int r;
        pt_element_t curr_pte;
-
-       r = kvm_read_guest_atomic(vcpu->kvm, gw->pte_gpa[level - 1],
+       gpa_t base_gpa, pte_gpa = gw->pte_gpa[level - 1];
+       u64 mask;
+       int r, index;
+
+       if (level == PT_PAGE_TABLE_LEVEL) {
+               mask = PTE_PREFETCH_NUM * sizeof(pt_element_t) - 1;
+               base_gpa = pte_gpa & ~mask;
+               index = (pte_gpa - base_gpa) / sizeof(pt_element_t);
+
+               r = kvm_read_guest_atomic(vcpu->kvm, base_gpa,
+                               gw->prefetch_ptes, sizeof(gw->prefetch_ptes));
+               curr_pte = gw->prefetch_ptes[index];
+       } else
+               r = kvm_read_guest_atomic(vcpu->kvm, pte_gpa,
                                  &curr_pte, sizeof(curr_pte));
+
        return r || curr_pte != gw->ptes[level - 1];
 }
 
+static void FNAME(pte_prefetch)(struct kvm_vcpu *vcpu, struct guest_walker *gw,
+                               u64 *sptep)
+{
+       struct kvm_mmu_page *sp;
+       pt_element_t *gptep = gw->prefetch_ptes;
+       u64 *spte;
+       int i;
+
+       sp = page_header(__pa(sptep));
+
+       if (sp->role.level > PT_PAGE_TABLE_LEVEL)
+               return;
+
+       if (sp->role.direct)
+               return __direct_pte_prefetch(vcpu, sp, sptep);
+
+       i = (sptep - sp->spt) & ~(PTE_PREFETCH_NUM - 1);
+       spte = sp->spt + i;
+
+       for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) {
+               pt_element_t gpte;
+               unsigned pte_access;
+               gfn_t gfn;
+               pfn_t pfn;
+               bool dirty;
+
+               if (spte == sptep)
+                       continue;
+
+               if (*spte != shadow_trap_nonpresent_pte)
+                       continue;
+
+               gpte = gptep[i];
+
+               if (FNAME(prefetch_invalid_gpte)(vcpu, sp, spte, gpte))
+                       continue;
+
+               pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
+               gfn = gpte_to_gfn(gpte);
+               dirty = is_dirty_gpte(gpte);
+               pfn = pte_prefetch_gfn_to_pfn(vcpu, gfn,
+                                     (pte_access & ACC_WRITE_MASK) && dirty);
+               if (is_error_pfn(pfn)) {
+                       kvm_release_pfn_clean(pfn);
+                       break;
+               }
+
+               mmu_set_spte(vcpu, spte, sp->role.access, pte_access, 0, 0,
+                            dirty, NULL, PT_PAGE_TABLE_LEVEL, gfn,
+                            pfn, true, true);
+       }
+}
+
 /*
  * 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 *gw,
                         int user_fault, int write_fault, int hlevel,
-                        int *ptwrite, pfn_t pfn)
+                        int *ptwrite, pfn_t pfn, bool map_writable)
 {
        unsigned access = gw->pt_access;
        struct kvm_mmu_page *sp = NULL;
-       u64 *sptep = NULL;
-       int uninitialized_var(level);
        bool dirty = is_dirty_gpte(gw->ptes[gw->level - 1]);
        int top_level;
        unsigned direct_access;
-       struct kvm_shadow_walk_iterator iterator;
+       struct kvm_shadow_walk_iterator it;
 
        if (!is_present_gpte(gw->ptes[gw->level - 1]))
                return NULL;
@@ -346,68 +464,60 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
        if (FNAME(gpte_changed)(vcpu, gw, top_level))
                goto out_gpte_changed;
 
-       for (shadow_walk_init(&iterator, vcpu, addr);
-            shadow_walk_okay(&iterator) && iterator.level > gw->level;
-            shadow_walk_next(&iterator)) {
+       for (shadow_walk_init(&it, vcpu, addr);
+            shadow_walk_okay(&it) && it.level > gw->level;
+            shadow_walk_next(&it)) {
                gfn_t table_gfn;
 
-               level = iterator.level;
-               sptep = iterator.sptep;
-
-               drop_large_spte(vcpu, sptep);
+               drop_large_spte(vcpu, it.sptep);
 
                sp = NULL;
-               if (!is_shadow_present_pte(*sptep)) {
-                       table_gfn = gw->table_gfn[level - 2];
-                       sp = kvm_mmu_get_page(vcpu, table_gfn, addr, level-1,
-                                             false, access, sptep);
+               if (!is_shadow_present_pte(*it.sptep)) {
+                       table_gfn = gw->table_gfn[it.level - 2];
+                       sp = kvm_mmu_get_page(vcpu, table_gfn, addr, it.level-1,
+                                             false, access, it.sptep);
                }
 
                /*
                 * Verify that the gpte in the page we've just write
                 * protected is still there.
                 */
-               if (FNAME(gpte_changed)(vcpu, gw, level - 1))
+               if (FNAME(gpte_changed)(vcpu, gw, it.level - 1))
                        goto out_gpte_changed;
 
                if (sp)
-                       link_shadow_page(sptep, sp);
+                       link_shadow_page(it.sptep, sp);
        }
 
        for (;
-            shadow_walk_okay(&iterator) && iterator.level > hlevel;
-            shadow_walk_next(&iterator)) {
+            shadow_walk_okay(&it) && it.level > hlevel;
+            shadow_walk_next(&it)) {
                gfn_t direct_gfn;
 
-               level = iterator.level;
-               sptep = iterator.sptep;
-
-               validate_direct_spte(vcpu, sptep, direct_access);
+               validate_direct_spte(vcpu, it.sptep, direct_access);
 
-               drop_large_spte(vcpu, sptep);
+               drop_large_spte(vcpu, it.sptep);
 
-               if (is_shadow_present_pte(*sptep))
+               if (is_shadow_present_pte(*it.sptep))
                        continue;
 
-               direct_gfn = gw->gfn & ~(KVM_PAGES_PER_HPAGE(level) - 1);
+               direct_gfn = gw->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
 
-               sp = kvm_mmu_get_page(vcpu, direct_gfn, addr, level-1,
-                                     true, direct_access, sptep);
-               link_shadow_page(sptep, sp);
+               sp = kvm_mmu_get_page(vcpu, direct_gfn, addr, it.level-1,
+                                     true, direct_access, it.sptep);
+               link_shadow_page(it.sptep, sp);
        }
 
-       sptep = iterator.sptep;
-       level = iterator.level;
+       mmu_set_spte(vcpu, it.sptep, access, gw->pte_access & access,
+                    user_fault, write_fault, dirty, ptwrite, it.level,
+                    gw->gfn, pfn, false, map_writable);
+       FNAME(pte_prefetch)(vcpu, gw, it.sptep);
 
-       mmu_set_spte(vcpu, sptep, access, gw->pte_access & access,
-                    user_fault, write_fault, dirty, ptwrite, level,
-                    gw->gfn, pfn, false, true);
-
-       return sptep;
+       return it.sptep;
 
 out_gpte_changed:
        if (sp)
-               kvm_mmu_put_page(sp, sptep);
+               kvm_mmu_put_page(sp, it.sptep);
        kvm_release_pfn_clean(pfn);
        return NULL;
 }
@@ -426,12 +536,11 @@ out_gpte_changed:
  *  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)
+static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
+                            bool no_apf)
 {
        int write_fault = error_code & PFERR_WRITE_MASK;
        int user_fault = error_code & PFERR_USER_MASK;
-       int fetch_fault = error_code & PFERR_FETCH_MASK;
        struct guest_walker walker;
        u64 *sptep;
        int write_pt = 0;
@@ -439,9 +548,9 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
        pfn_t pfn;
        int level = PT_PAGE_TABLE_LEVEL;
        unsigned long mmu_seq;
+       bool map_writable;
 
        pgprintk("%s: addr %lx err %x\n", __func__, addr, error_code);
-       kvm_mmu_audit(vcpu, "pre page fault");
 
        r = mmu_topup_memory_caches(vcpu);
        if (r)
@@ -450,15 +559,14 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
        /*
         * Look up the guest pte for the faulting address.
         */
-       r = FNAME(walk_addr)(&walker, vcpu, addr, write_fault, user_fault,
-                            fetch_fault);
+       r = FNAME(walk_addr)(&walker, vcpu, addr, error_code);
 
        /*
         * The page is not mapped by the guest.  Let the guest handle it.
         */
        if (!r) {
                pgprintk("%s: guest page fault\n", __func__);
-               inject_page_fault(vcpu, addr, walker.error_code);
+               inject_page_fault(vcpu);
                vcpu->arch.last_pt_write_count = 0; /* reset fork detector */
                return 0;
        }
@@ -470,18 +578,26 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
 
        mmu_seq = vcpu->kvm->mmu_notifier_seq;
        smp_rmb();
-       pfn = gfn_to_pfn(vcpu->kvm, walker.gfn);
+
+       if (try_async_pf(vcpu, no_apf, walker.gfn, addr, &pfn, write_fault,
+                        &map_writable))
+               return 0;
 
        /* mmio */
        if (is_error_pfn(pfn))
                return kvm_handle_bad_page(vcpu->kvm, walker.gfn, pfn);
 
+       if (!map_writable)
+               walker.pte_access &= ~ACC_WRITE_MASK;
+
        spin_lock(&vcpu->kvm->mmu_lock);
        if (mmu_notifier_retry(vcpu, mmu_seq))
                goto out_unlock;
+
+       trace_kvm_mmu_audit(vcpu, AUDIT_PRE_PAGE_FAULT);
        kvm_mmu_free_some_pages(vcpu);
        sptep = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
-                            level, &write_pt, pfn);
+                            level, &write_pt, pfn, map_writable);
        (void)sptep;
        pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __func__,
                 sptep, *sptep, write_pt);
@@ -490,7 +606,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
                vcpu->arch.last_pt_write_count = 0; /* reset fork detector */
 
        ++vcpu->stat.pf_fixed;
-       kvm_mmu_audit(vcpu, "post page fault (fixed)");
+       trace_kvm_mmu_audit(vcpu, AUDIT_POST_PAGE_FAULT);
        spin_unlock(&vcpu->kvm->mmu_lock);
 
        return write_pt;
@@ -567,10 +683,25 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr, u32 access,
        gpa_t gpa = UNMAPPED_GVA;
        int r;
 
-       r = FNAME(walk_addr)(&walker, vcpu, vaddr,
-                            !!(access & PFERR_WRITE_MASK),
-                            !!(access & PFERR_USER_MASK),
-                            !!(access & PFERR_FETCH_MASK));
+       r = FNAME(walk_addr)(&walker, vcpu, vaddr, access);
+
+       if (r) {
+               gpa = gfn_to_gpa(walker.gfn);
+               gpa |= vaddr & ~PAGE_MASK;
+       } else if (error)
+               *error = walker.error_code;
+
+       return gpa;
+}
+
+static gpa_t FNAME(gva_to_gpa_nested)(struct kvm_vcpu *vcpu, gva_t vaddr,
+                                     u32 access, u32 *error)
+{
+       struct guest_walker walker;
+       gpa_t gpa = UNMAPPED_GVA;
+       int r;
+
+       r = FNAME(walk_addr_nested)(&walker, vcpu, vaddr, access);
 
        if (r) {
                gpa = gfn_to_gpa(walker.gfn);
@@ -615,12 +746,19 @@ static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
  * Using the cached information from sp->gfns is safe because:
  * - The spte has a reference to the struct page, so the pfn for a given gfn
  *   can't change unless all sptes pointing to it are nuked first.
+ *
+ * Note:
+ *   We should flush all tlbs if spte is dropped even though guest is
+ *   responsible for it. Since if we don't, kvm_mmu_notifier_invalidate_page
+ *   and kvm_mmu_notifier_invalidate_range_start detect the mapping page isn't
+ *   used by guest then tlbs are not flushed, so guest is allowed to access the
+ *   freed pages.
+ *   And we increase kvm->tlbs_dirty to delay tlbs flush in this case.
  */
-static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
-                           bool clear_unsync)
+static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
 {
        int i, offset, nr_present;
-       bool reset_host_protection;
+       bool host_writable;
        gpa_t first_pte_gpa;
 
        offset = nr_present = 0;
@@ -649,15 +787,16 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
                        return -EINVAL;
 
                gfn = gpte_to_gfn(gpte);
-               if (gfn != sp->gfns[i] ||
-                     !is_present_gpte(gpte) || !(gpte & PT_ACCESSED_MASK)) {
-                       u64 nonpresent;
 
-                       if (is_present_gpte(gpte) || !clear_unsync)
-                               nonpresent = shadow_trap_nonpresent_pte;
-                       else
-                               nonpresent = shadow_notrap_nonpresent_pte;
-                       drop_spte(vcpu->kvm, &sp->spt[i], nonpresent);
+               if (FNAME(prefetch_invalid_gpte)(vcpu, sp, &sp->spt[i], gpte)) {
+                       vcpu->kvm->tlbs_dirty++;
+                       continue;
+               }
+
+               if (gfn != sp->gfns[i]) {
+                       drop_spte(vcpu->kvm, &sp->spt[i],
+                                     shadow_trap_nonpresent_pte);
+                       vcpu->kvm->tlbs_dirty++;
                        continue;
                }
 
@@ -665,14 +804,14 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
                pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
                if (!(sp->spt[i] & SPTE_HOST_WRITEABLE)) {
                        pte_access &= ~ACC_WRITE_MASK;
-                       reset_host_protection = 0;
+                       host_writable = 0;
                } else {
-                       reset_host_protection = 1;
+                       host_writable = 1;
                }
                set_spte(vcpu, &sp->spt[i], pte_access, 0, 0,
                         is_dirty_gpte(gpte), PT_PAGE_TABLE_LEVEL, gfn,
                         spte_to_pfn(sp->spt[i]), true, false,
-                        reset_host_protection);
+                        host_writable);
        }
 
        return !nr_present;