diff options
Diffstat (limited to 'tools/testing/selftests/powerpc/security/spectre_v2.c')
| -rw-r--r-- | tools/testing/selftests/powerpc/security/spectre_v2.c | 29 |
1 files changed, 23 insertions, 6 deletions
diff --git a/tools/testing/selftests/powerpc/security/spectre_v2.c b/tools/testing/selftests/powerpc/security/spectre_v2.c index 8c6b982af2a8..5b2abb719ef2 100644 --- a/tools/testing/selftests/powerpc/security/spectre_v2.c +++ b/tools/testing/selftests/powerpc/security/spectre_v2.c @@ -125,8 +125,6 @@ static enum spectre_v2_state get_sysfs_state(void) #define PM_BR_PRED_PCACHE 0x048a0 // P9 only #define PM_BR_MPRED_PCACHE 0x048b0 // P9 only -#define SPRN_PVR 287 - int spectre_v2_test(void) { enum spectre_v2_state state; @@ -134,6 +132,9 @@ int spectre_v2_test(void) s64 miss_percent; bool is_p9; + // The PMU events we use only work on Power8 or later + SKIP_IF(!have_hwcap2(PPC_FEATURE2_ARCH_2_07)); + state = get_sysfs_state(); if (state == UNKNOWN) { printf("Error: couldn't determine spectre_v2 mitigation state?\n"); @@ -181,8 +182,24 @@ 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"); + printf("Possible mismatch between reported & actual mitigation\n"); + return 1; } break; @@ -190,14 +207,14 @@ int spectre_v2_test(void) // This seems to affect userspace branch prediction a bit? if (miss_percent > 25) { printf("Branch misses > 25%% unexpected in this configuration!\n"); - printf("Possible mis-match between reported & actual mitigation\n"); + printf("Possible mismatch between reported & actual mitigation\n"); return 1; } break; case COUNT_CACHE_DISABLED: if (miss_percent < 95) { - printf("Branch misses < 20%% unexpected in this configuration!\n"); - printf("Possible mis-match between reported & actual mitigation\n"); + printf("Branch misses < 95%% unexpected in this configuration!\n"); + printf("Possible mismatch between reported & actual mitigation\n"); return 1; } break; |