KVM: MMU: add missing reserved bits check in speculative path

In the speculative path, we should check guest pte's reserved bits just as
the real processor does
Reported-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/kvm/mmu.c

@@ -2697,6 +2697,9 @@ static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu,
 		return;
         }
 
+	if (is_rsvd_bits_set(vcpu, *(u64 *)new, PT_PAGE_TABLE_LEVEL))
+		return;
+
 	++vcpu->kvm->stat.mmu_pte_updated;
 	if (!sp->role.cr4_pae)
 		paging32_update_pte(vcpu, sp, spte, new);
@@ -2775,6 +2778,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
 		       bool guest_initiated)
 {
 	gfn_t gfn = gpa >> PAGE_SHIFT;
+	union kvm_mmu_page_role mask = { .word = 0 };
 	struct kvm_mmu_page *sp;
 	struct hlist_node *node;
 	LIST_HEAD(invalid_list);
@@ -2849,6 +2853,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
 		}
 	}
 
+	mask.cr0_wp = mask.cr4_pae = mask.nxe = 1;
 	for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn, node) {
 		pte_size = sp->role.cr4_pae ? 8 : 4;
 		misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1);
@@ -2896,7 +2901,9 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
 		while (npte--) {
 			entry = *spte;
 			mmu_pte_write_zap_pte(vcpu, sp, spte);
-			if (gentry)
+			if (gentry &&
+			      !((sp->role.word ^ vcpu->arch.mmu.base_role.word)
+			      & mask.word))
 				mmu_pte_write_new_pte(vcpu, sp, spte, &gentry);
 			if (!remote_flush && need_remote_flush(entry, *spte))
 				remote_flush = true;

arch/x86/kvm/paging_tmpl.h

@@ -638,8 +638,9 @@ 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)) {
+		if (is_rsvd_bits_set(vcpu, gpte, PT_PAGE_TABLE_LEVEL)
+		      || gfn != sp->gfns[i] || !is_present_gpte(gpte)
+		      || !(gpte & PT_ACCESSED_MASK)) {
 			u64 nonpresent;
 
 			if (is_present_gpte(gpte) || !clear_unsync)