powerpc/pseries: Fix update of LPAR security flavor after LPM

After LPM, when migrating from a system with security mitigation enabled
to a system with mitigation disabled, the security flavor exposed in
/proc is not correctly set back to 0.

Do not assume the value of the security flavor is set to 0 when entering
init_cpu_char_feature_flags(), so when called after a LPM, the value is
set correctly even if the mitigation are not turned off.

Fixes: 6ce56e1ac380 ("powerpc/pseries: export LPAR security flavor in lparcfg")
Cc: stable@vger.kernel.org # v5.13+
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210805152308.33988-1-ldufour@linux.ibm.com

diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 6b08866..0dfaa6a 100644 (file)
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -539,9 +539,10 @@ static void init_cpu_char_feature_flags(struct h_cpu_char_result *result)
         * H_CPU_BEHAV_FAVOUR_SECURITY_H could be set only if
         * H_CPU_BEHAV_FAVOUR_SECURITY is.
         */
-       if (!(result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY))
+       if (!(result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY)) {
                security_ftr_clear(SEC_FTR_FAVOUR_SECURITY);
-       else if (result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY_H)
+               pseries_security_flavor = 0;
+       } else if (result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY_H)
                pseries_security_flavor = 1;
        else
                pseries_security_flavor = 2;