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: 6ce56e1a ("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

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;