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

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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211207130557.40566-1-cascardo@canonical.com

diff --git a/tools/testing/selftests/powerpc/security/spectre_v2.c b/tools/testing/selftests/powerpc/security/spectre_v2.c
index adc2b7294e5fddb54150bd797b04efc5825b3c3d..83647b8277e7dfa2efa7a45e9bb327dd30a02208 100644 (file)
--- 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;