diff mbox series

selftests/powerpc/spectre_v2: Return skip code when miss_percent is high

Message ID 20211207130557.40566-1-cascardo@canonical.com
State Accepted
Commit 3c42e9542050d49610077e083c7c3f5fd5e26820
Headers show
Series selftests/powerpc/spectre_v2: Return skip code when miss_percent is high | expand

Commit Message

Thadeu Lima de Souza Cascardo Dec. 7, 2021, 1:05 p.m. UTC
A mis-match between reported and actual mitigation is not restricted to the
Vulnerable case. The guest might also report the mitigation as "Software
count cache flush" and the host will still mitigate with branch cache
disabled.

So, instead of skipping depending on the detected mitigation, simply skip
whenever the detected miss_percent is the expected one for a fully
mitigated system, that is, above 95%.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
---
 tools/testing/selftests/powerpc/security/spectre_v2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Michael Ellerman Dec. 15, 2021, 12:24 a.m. UTC | #1
On Tue, 7 Dec 2021 10:05:57 -0300, Thadeu Lima de Souza Cascardo wrote:
> A mis-match between reported and actual mitigation is not restricted to the
> Vulnerable case. The guest might also report the mitigation as "Software
> count cache flush" and the host will still mitigate with branch cache
> disabled.
> 
> So, instead of skipping depending on the detected mitigation, simply skip
> whenever the detected miss_percent is the expected one for a fully
> mitigated system, that is, above 95%.
> 
> [...]

Applied to powerpc/next.

[1/1] selftests/powerpc/spectre_v2: Return skip code when miss_percent is high
      https://git.kernel.org/powerpc/c/3c42e9542050d49610077e083c7c3f5fd5e26820

cheers
diff mbox series

Patch

diff --git a/tools/testing/selftests/powerpc/security/spectre_v2.c b/tools/testing/selftests/powerpc/security/spectre_v2.c
index adc2b7294e5f..83647b8277e7 100644
--- a/tools/testing/selftests/powerpc/security/spectre_v2.c
+++ b/tools/testing/selftests/powerpc/security/spectre_v2.c
@@ -193,7 +193,7 @@  int spectre_v2_test(void)
 			 * We are not vulnerable and reporting otherwise, so
 			 * missing such a mismatch is safe.
 			 */
-			if (state == VULNERABLE)
+			if (miss_percent > 95)
 				return 4;
 
 			return 1;