2 files changed, 26 insertions, 7 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 6c67b230e958..5cd8b4ec3a01 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -156,6 +156,8 @@ module_param(oos_shadow, bool, 0644);
 #define CREATE_TRACE_POINTS
 #include "mmutrace.h"
 
+#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
+
 #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
 
 struct kvm_rmap_desc {
@@ -1754,7 +1756,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
                     unsigned pte_access, int user_fault,
                     int write_fault, int dirty, int level,
                     gfn_t gfn, pfn_t pfn, bool speculative,
-                    bool can_unsync)
+                    bool can_unsync, bool reset_host_protection)
 {
         u64 spte;
         int ret = 0;
@@ -1781,6 +1783,9 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
                 spte |= kvm_x86_ops->get_mt_mask(vcpu, gfn,
                         kvm_is_mmio_pfn(pfn));
 
+        if (reset_host_protection)
+                spte |= SPTE_HOST_WRITEABLE;
+
         spte |= (u64)pfn << PAGE_SHIFT;
 
         if ((pte_access & ACC_WRITE_MASK)
@@ -1826,7 +1831,8 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
                          unsigned pt_access, unsigned pte_access,
                          int user_fault, int write_fault, int dirty,
                          int *ptwrite, int level, gfn_t gfn,
-                         pfn_t pfn, bool speculative)
+                         pfn_t pfn, bool speculative,
+                         bool reset_host_protection)
 {
         int was_rmapped = 0;
         int was_writeble = is_writeble_pte(*sptep);
@@ -1858,7 +1864,8 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
         }
 
         if (set_spte(vcpu, sptep, pte_access, user_fault, write_fault,
-                      dirty, level, gfn, pfn, speculative, true)) {
+                      dirty, level, gfn, pfn, speculative, true,
+                      reset_host_protection)) {
                 if (write_fault)
                         *ptwrite = 1;
                 kvm_x86_ops->tlb_flush(vcpu);
@@ -1906,7 +1913,7 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
                 if (iterator.level == level) {
                         mmu_set_spte(vcpu, iterator.sptep, ACC_ALL, ACC_ALL,
                                      0, write, 1, &pt_write,
-                                     level, gfn, pfn, false);
+                                     level, gfn, pfn, false, true);
                         ++vcpu->stat.pf_fixed;
                         break;
                 }
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index d2fec9c12d22..72558f8ff3f5 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -273,9 +273,13 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
         if (mmu_notifier_retry(vcpu, vcpu->arch.update_pte.mmu_seq))
                 return;
         kvm_get_pfn(pfn);
+        /*
+         * we call mmu_set_spte() with reset_host_protection = true beacuse that
+         * vcpu->arch.update_pte.pfn was fetched from get_user_pages(write = 1).
+         */
         mmu_set_spte(vcpu, spte, page->role.access, pte_access, 0, 0,
                      gpte & PT_DIRTY_MASK, NULL, PT_PAGE_TABLE_LEVEL,
-                     gpte_to_gfn(gpte), pfn, true);
+                     gpte_to_gfn(gpte), pfn, true, true);
 }
 
 /*
@@ -308,7 +312,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
                                      user_fault, write_fault,
                                      gw->ptes[gw->level-1] & PT_DIRTY_MASK,
                                      ptwrite, level,
-                                     gw->gfn, pfn, false);
+                                     gw->gfn, pfn, false, true);
                         break;
                 }
 
@@ -558,6 +562,7 @@ static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
 static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
 {
         int i, offset, nr_present;
+        bool reset_host_protection;
 
         offset = nr_present = 0;
 
@@ -595,9 +600,16 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
 
                 nr_present++;
                 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;
+                } else {
+                        reset_host_protection = 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);
+                         spte_to_pfn(sp->spt[i]), true, false,
+                         reset_host_protection);
         }
 
         return !nr_present;