Merge pull request #12 from yuandengliang/fix_access_no_pte

do not performen check if there is no pte

guest/x86/access.c

@@ -712,8 +712,11 @@ static int ac_test_do_access(ac_test_t *at)
                   "unexpected access");
     ac_test_check(at, &success, fault && e != at->expected_error,
                   "error code %x expected %x", e, at->expected_error);
-    ac_test_check(at, &success, at->ptep && *at->ptep != at->expected_pte,
+    if (at->ptep) {
+        ac_test_check(at, &success, at->ptep && *at->ptep != at->expected_pte,
                   "pte %x expected %x", *at->ptep, at->expected_pte);
+    }
+
     ac_test_check(at, &success,
                   !pt_match(*at->pdep, at->expected_pde, at->ignore_pde),
                   "pde %x expected %x", *at->pdep, at->expected_pde);
@@ -1001,7 +1004,6 @@ int main(void)
 
     cpuid_7_ebx = cpuid(7).b;
     cpuid_7_ecx = cpuid(7).c;
-
     printf("starting test\n\n");
     page_table_levels = 4;
     r = ac_test_run();