This is a note to let you know that I've just added the patch titled
selftests/powerpc/spectre_v2: Return skip code when miss_percent is high
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
selftests-powerpc-spectre_v2-return-skip-code-when-m.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 663467b6a1d6b37a325ed115f2dd3118f82eb589
Author: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxxxxx>
Date: Tue Dec 7 10:05:57 2021 -0300
selftests/powerpc/spectre_v2: Return skip code when miss_percent is high
[ Upstream commit 3c42e9542050d49610077e083c7c3f5fd5e26820 ]
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@xxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211207130557.40566-1-cascardo@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/testing/selftests/powerpc/security/spectre_v2.c b/tools/testing/selftests/powerpc/security/spectre_v2.c
index adc2b7294e5fd..83647b8277e7d 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;
