selftests: kvm: return Kselftest Skip code for skipped tests

When kvm test is skipped because of unmet dependencies and/or unsupported
configuration, it exits with error which is treated as a fail by the
Kselftest framework. This leads to false negative result even when the test
could not be run.

Change it to return kselftest skip code when a test gets skipped to clearly
report that the test could not be run.

Change it to use ksft_exit_skip() when the test is skipped. In addition,
refine test_assert() message to include strerror() string and add explicit
check for EACCES to cleary identify when test doesn't run when access is
denied to resources required e.g: open /dev/kvm failed, rc: -1 errno: 13

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>

tools/testing/selftests/kvm/lib/assert.c

@@ -13,6 +13,8 @@
 #include <execinfo.h>
 #include <sys/syscall.h>
 
+#include "../../kselftest.h"
+
 /* Dumps the current stack trace to stderr. */
 static void __attribute__((noinline)) test_dump_stack(void);
 static void test_dump_stack(void)
@@ -70,8 +72,9 @@ test_assert(bool exp, const char *exp_str,
 
 		fprintf(stderr, "==== Test Assertion Failure ====\n"
 			"  %s:%u: %s\n"
-			"  pid=%d tid=%d\n",
+			"  pid=%d tid=%d - %s\n",
-			file, line, exp_str, getpid(), gettid());
+			file, line, exp_str, getpid(), gettid(),
+			strerror(errno));
 		test_dump_stack();
 		if (fmt) {
 			fputs("  ", stderr);
@@ -80,6 +83,8 @@ test_assert(bool exp, const char *exp_str,
 		}
 		va_end(ap);
 
+		if (errno == EACCES)
+			ksft_exit_skip("Access denied - Exiting.\n");
 		exit(254);
 	}
 

tools/testing/selftests/kvm/vmx_tsc_adjust_test.c

@@ -28,6 +28,8 @@
 #include <string.h>
 #include <sys/ioctl.h>
 
+#include "../kselftest.h"
+
 #ifndef MSR_IA32_TSC_ADJUST
 #define MSR_IA32_TSC_ADJUST 0x3b
 #endif