AcoSail/kernel_optimize_test
8
0
Fork 0
forked from luck/tmp_suning_uos_patched
Code Pull Requests Activity

selftests/powerpc: Return skip code for spectre_v2

Browse Source 
When running under older versions of qemu of under newer versions with
old machine types, some security features will not be reported to the
guest. This will lead the guest OS to consider itself Vulnerable to
spectre_v2.

So, spectre_v2 test fails in such cases when the host is mitigated and
miss predictions cannot be detected as expected by the test.

Make it return the skip code instead, for this particular case. We
don't want to miss the case when the test fails and the system reports
as mitigated or not affected. But it is not a problem to miss failures
when the system reports as Vulnerable.

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/20200728155039.401445-1-cascardo@canonical.com
This commit is contained in:
Thadeu Lima de Souza Cascardo 2020-07-28 12:50:39 -03:00 committed by Michael Ellerman
parent b859c95cf4
commit f3054ffd71
1 changed files with 10 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
tools/testing/selftests/powerpc/security/spectre_v2.c
View File

@ -183,6 +183,16 @@ int spectre_v2_test(void)
if (miss_percent > 15) {
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 (state == VULNERABLE)
return 4;
return 1;
}
break;