4.9-stable review patch. If anyone has any objections, please let me know.
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From: Mauricio Faria de Oliveira mauricfo@linux.vnet.ibm.com
commit 6232774f1599028a15418179d17f7df47ede770a upstream.
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") Depends-on: 19887d6a28e2 ("powerpc: Move default security feature flags") Signed-off-by: Mauricio Faria de Oliveira mauricfo@linux.vnet.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/platforms/pseries/setup.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
--- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -453,6 +453,10 @@ static void __init find_and_init_phbs(vo
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) security_ftr_set(SEC_FTR_SPEC_BAR_ORI31);
@@ -492,6 +496,13 @@ void pseries_setup_rfi_flush(void) bool enable; long rc;
+ /* + * 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) init_cpu_char_feature_flags(&result);