diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 64adb61..3318bde 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -287,6 +287,13 @@ struct kvm_mmu {
 	union kvm_mmu_page_role base_role;
 	bool direct_map;
 
+	/*
+	 * Bitmap; bit set = permission fault
+	 * Byte index: page fault error code [4:1]
+	 * Bit index: pte permissions in ACC_* format
+	 */
+	u8 permissions[16];
+
 	u64 *pae_root;
 	u64 *lm_root;
 	u64 rsvd_bits_mask[2][4];
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f297a2c..9c61889 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3516,6 +3516,38 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
 	}
 }
 
+static void update_permission_bitmask(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu)
+{
+	unsigned bit, byte, pfec;
+	u8 map;
+	bool fault, x, w, u, wf, uf, ff, smep;
+
+	smep = kvm_read_cr4_bits(vcpu, X86_CR4_SMEP);
+	for (byte = 0; byte < ARRAY_SIZE(mmu->permissions); ++byte) {
+		pfec = byte << 1;
+		map = 0;
+		wf = pfec & PFERR_WRITE_MASK;
+		uf = pfec & PFERR_USER_MASK;
+		ff = pfec & PFERR_FETCH_MASK;
+		for (bit = 0; bit < 8; ++bit) {
+			x = bit & ACC_EXEC_MASK;
+			w = bit & ACC_WRITE_MASK;
+			u = bit & ACC_USER_MASK;
+
+			/* Not really needed: !nx will cause pte.nx to fault */
+			x |= !mmu->nx;
+			/* Allow supervisor writes if !cr0.wp */
+			w |= !is_write_protection(vcpu) && !uf;
+			/* Disallow supervisor fetches of user code if cr4.smep */
+			x &= !(smep && u && !uf);
+
+			fault = (ff && !x) || (uf && !u) || (wf && !w);
+			map |= fault << bit;
+		}
+		mmu->permissions[byte] = map;
+	}
+}
+
 static int paging64_init_context_common(struct kvm_vcpu *vcpu,
 					struct kvm_mmu *context,
 					int level)
@@ -3524,6 +3556,7 @@ static int paging64_init_context_common(struct kvm_vcpu *vcpu,
 	context->root_level = level;
 
 	reset_rsvds_bits_mask(vcpu, context);
+	update_permission_bitmask(vcpu, context);
 
 	ASSERT(is_pae(vcpu));
 	context->new_cr3 = paging_new_cr3;
@@ -3552,6 +3585,7 @@ static int paging32_init_context(struct kvm_vcpu *vcpu,
 	context->root_level = PT32_ROOT_LEVEL;
 
 	reset_rsvds_bits_mask(vcpu, context);
+	update_permission_bitmask(vcpu, context);
 
 	context->new_cr3 = paging_new_cr3;
 	context->page_fault = paging32_page_fault;
@@ -3612,6 +3646,8 @@ static int init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
 		context->gva_to_gpa = paging32_gva_to_gpa;
 	}
 
+	update_permission_bitmask(vcpu, context);
+
 	return 0;
 }
 
@@ -3687,6 +3723,8 @@ static int init_kvm_nested_mmu(struct kvm_vcpu *vcpu)
 		g_context->gva_to_gpa = paging32_gva_to_gpa_nested;
 	}
 
+	update_permission_bitmask(vcpu, g_context);
+
 	return 0;
 }
 
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 2832081..5846607 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -89,17 +89,14 @@ static inline bool is_write_protection(struct kvm_vcpu *vcpu)
 	return kvm_read_cr0_bits(vcpu, X86_CR0_WP);
 }
 
-static inline bool check_write_user_access(struct kvm_vcpu *vcpu,
-					   bool write_fault, bool user_fault,
-					   unsigned long pte)
+/*
+ * Will a fault with a given page-fault error code (pfec) cause a permission
+ * fault with the given access (in ACC_* format)?
+ */
+static inline bool permission_fault(struct kvm_mmu *mmu, unsigned pte_access,
+				    unsigned pfec)
 {
-	if (unlikely(write_fault && !is_writable_pte(pte)
-	      && (user_fault || is_write_protection(vcpu))))
-		return false;
-
-	if (unlikely(user_fault && !(pte & PT_USER_MASK)))
-		return false;
-
-	return true;
+	return (mmu->permissions[pfec >> 1] >> pte_access) & 1;
 }
+
 #endif
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 35a05dd..8f6c59f 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -169,7 +169,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
 	pt_element_t pte;
 	pt_element_t __user *uninitialized_var(ptep_user);
 	gfn_t table_gfn;
-	unsigned index, pt_access, uninitialized_var(pte_access);
+	unsigned index, pt_access, pte_access;
 	gpa_t pte_gpa;
 	bool eperm, last_gpte;
 	int offset;
@@ -237,24 +237,9 @@ retry_walk:
 			goto error;
 		}
 
-		if (!check_write_user_access(vcpu, write_fault, user_fault,
-					  pte))
-			eperm = true;
-
-#if PTTYPE == 64
-		if (unlikely(fetch_fault && (pte & PT64_NX_MASK)))
-			eperm = true;
-#endif
+		pte_access = pt_access & gpte_access(vcpu, pte);
 
 		last_gpte = FNAME(is_last_gpte)(walker, vcpu, mmu, pte);
-		if (last_gpte) {
-			pte_access = pt_access & gpte_access(vcpu, pte);
-			/* check if the kernel is fetching from user page */
-			if (unlikely(pte_access & PT_USER_MASK) &&
-			    kvm_read_cr4_bits(vcpu, X86_CR4_SMEP))
-				if (fetch_fault && !user_fault)
-					eperm = true;
-		}
 
 		walker->ptes[walker->level - 1] = pte;
 
@@ -284,10 +269,11 @@ retry_walk:
 			break;
 		}
 
-		pt_access &= gpte_access(vcpu, pte);
+		pt_access &= pte_access;
 		--walker->level;
 	}
 
+	eperm |= permission_fault(mmu, pte_access, access);
 	if (unlikely(eperm)) {
 		errcode |= PFERR_PRESENT_MASK;
 		goto error;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c4d451e..db97dda 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3672,20 +3672,17 @@ static int vcpu_mmio_gva_to_gpa(struct kvm_vcpu *vcpu, unsigned long gva,
 				gpa_t *gpa, struct x86_exception *exception,
 				bool write)
 {
-	u32 access = (kvm_x86_ops->get_cpl(vcpu) == 3) ? PFERR_USER_MASK : 0;
+	u32 access = ((kvm_x86_ops->get_cpl(vcpu) == 3) ? PFERR_USER_MASK : 0)
+		| (write ? PFERR_WRITE_MASK : 0);
 
-	if (vcpu_match_mmio_gva(vcpu, gva) &&
-		  check_write_user_access(vcpu, write, access,
-		  vcpu->arch.access)) {
+	if (vcpu_match_mmio_gva(vcpu, gva)
+	    && !permission_fault(vcpu->arch.walk_mmu, vcpu->arch.access, access)) {
 		*gpa = vcpu->arch.mmio_gfn << PAGE_SHIFT |
 					(gva & (PAGE_SIZE - 1));
 		trace_vcpu_match_mmio(gva, *gpa, write, false);
 		return 1;
 	}
 
-	if (write)
-		access |= PFERR_WRITE_MASK;
-
 	*gpa = vcpu->arch.walk_mmu->gva_to_gpa(vcpu, gva, access, exception);
 
 	if (*gpa == UNMAPPED_GVA)
