Commit e9fbc47b authored by Borislav Petkov (AMD)'s avatar Borislav Petkov (AMD)
Browse files

x86/srso: Disable the mitigation on unaffected configurations 



Skip the srso cmd line parsing which is not needed on Zen1/2 with SMT
disabled and with the proper microcode applied (latter should be the
case anyway) as those are not affected.

Fixes: 5a15d834 ("x86/srso: Tie SBPB bit setting to microcode patch detection")
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230813104517.3346-1-bp@alien8.de
parent f58d6fbc

arch/x86/kernel/cpu/bugs.c

+6 −1
Original line number Diff line number Diff line
@@ -2418,8 +2418,10 @@ static void __init srso_select_mitigation(void) 
		 * IBPB microcode has been applied.

		 */

		if ((boot_cpu_data.x86 < 0x19) &&

		    (!cpu_smt_possible() || (cpu_smt_control == CPU_SMT_DISABLED)))

		    (!cpu_smt_possible() || (cpu_smt_control == CPU_SMT_DISABLED))) {

			setup_force_cpu_cap(X86_FEATURE_SRSO_NO);

			return;

		}

	}



	if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB) {
@@ -2696,6 +2698,9 @@ static ssize_t retbleed_show_state(char *buf) 


static ssize_t srso_show_state(char *buf)

{

	if (boot_cpu_has(X86_FEATURE_SRSO_NO))

		return sysfs_emit(buf, "Not affected\n");



	return sysfs_emit(buf, "%s%s\n",

			  srso_strings[srso_mitigation],

			  (cpu_has_ibpb_brtype_microcode() ? "" : ", no microcode"));