diff options
Diffstat (limited to 'tools/testing/selftests/powerpc')
| -rw-r--r-- | tools/testing/selftests/powerpc/security/spectre_v2.c | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/tools/testing/selftests/powerpc/security/spectre_v2.c b/tools/testing/selftests/powerpc/security/spectre_v2.c index 80dc97e3ec57..0e231e89bfa4 100644 --- a/tools/testing/selftests/powerpc/security/spectre_v2.c +++ b/tools/testing/selftests/powerpc/security/spectre_v2.c @@ -182,17 +182,23 @@ int spectre_v2_test(void) case COUNT_CACHE_FLUSH_HW: // These should all not affect userspace branch prediction if (miss_percent > 15) { + if (miss_percent > 95) { + /* + * Such a mismatch may be caused by a system being unaware + * the count cache is disabled. This may be to enable + * guest migration between hosts with different settings. + * Return skip code to avoid detecting this as an error. + * We are not vulnerable and reporting otherwise, so + * missing such a mismatch is safe. + */ + printf("Branch misses > 95%% unexpected in this configuration.\n"); + printf("Count cache likely disabled without Linux knowing.\n"); + if (state == COUNT_CACHE_FLUSH_SW) + printf("WARNING: Kernel performing unnecessary flushes.\n"); + return 4; + } printf("Branch misses > 15%% unexpected in this configuration!\n"); printf("Possible mis-match between reported & actual mitigation\n"); - /* - * Such a mismatch may be caused by a guest system - * reporting as vulnerable when the host is mitigated. - * Return skip code to avoid detecting this as an error. - * We are not vulnerable and reporting otherwise, so - * missing such a mismatch is safe. - */ - if (miss_percent > 95) - return 4; return 1; } |