[PATCH 2/2] powerpc/pseries: Restore default security feature flags on setup
Mauricio Faria de Oliveira
mauricfo at linux.vnet.ibm.com
Sat Mar 31 04:28:25 AEDT 2018
After migration the security feature flags might have changed (e.g.,
destination system with unpatched firmware), but some flags are not
set/clear again in init_cpu_char_feature_flags() because it assumes
the security flags to be the defaults.
Additionally, if the H_GET_CPU_CHARACTERISTICS hypercall fails then
init_cpu_char_feature_flags() does not run again, which potentially
might leave the system in an insecure or sub-optimal configuration.
So, just restore the security feature flags to the defaults assumed
by init_cpu_char_feature_flags() so it can set/clear them correctly,
and to ensure safe settings are in place in case the hypercall fail.
Fixes: f636c14790ea ("powerpc/pseries: Set or clear security feature flags")
Signed-off-by: Mauricio Faria de Oliveira <mauricfo at linux.vnet.ibm.com>
arch/powerpc/platforms/pseries/setup.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index b11564f..2581fc8 100644
@@ -462,6 +462,10 @@ static void __init find_and_init_phbs(void)
static void init_cpu_char_feature_flags(struct h_cpu_char_result *result)
+ * The features below are disabled by default, so we instead look to see
+ * if firmware has *enabled* them, and set them if so.
if (result->character & H_CPU_CHAR_SPEC_BAR_ORI31)
@@ -501,6 +505,13 @@ void pseries_setup_rfi_flush(void)
+ * Set features to the defaults assumed by init_cpu_char_feature_flags()
+ * so it can set/clear again any features that might have changed after
+ * migration, and in case the hypercall fails and it is not even called.
+ powerpc_security_features = SEC_FTR_DEFAULT;
rc = plpar_get_cpu_characteristics(&result);
if (rc == H_SUCCESS)
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