KVM: MMU audit: audit_mappings tweaks

- Fail early in case gfn_to_pfn returns is_error_pfn.
- For the pre pte write case, avoid spurious "gva is valid but spte is notrap"
  messages (the emulation code does the guest write first, so this particular
  case is OK).
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/kvm/mmu.c

@@ -3117,6 +3117,11 @@ static void audit_mappings_page(struct kvm_vcpu *vcpu, u64 page_pte,
 			pfn_t pfn = gfn_to_pfn(vcpu->kvm, gfn);
 			hpa_t hpa = (hpa_t)pfn << PAGE_SHIFT;
 
+			if (is_error_pfn(pfn)) {
+				kvm_release_pfn_clean(pfn);
+				continue;
+			}
+
 			if (is_shadow_present_pte(ent)
 			    && (ent & PT64_BASE_ADDR_MASK) != hpa)
 				printk(KERN_ERR "xx audit error: (%s) levels %d"
@@ -3288,7 +3293,8 @@ static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg)
 	audit_msg = msg;
 	audit_rmap(vcpu);
 	audit_write_protection(vcpu);
-	audit_mappings(vcpu);
+	if (strcmp("pre pte write", audit_msg) != 0)
+		audit_mappings(vcpu);
 	audit_writable_sptes_have_rmaps(vcpu);
 	dbg = olddbg;
 }