| From | Josh Poimboeuf <> | Subject | [PATCH v3 01/20] x86/srso: Fix srso_show_state() side effect | Date | Mon, 4 Sep 2023 22:04:45 -0700 |
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Reading the 'spec_rstack_overflow' sysfs file can trigger an unnecessary MSR write, and possibly even a (handled) exception if the microcode hasn't been updated.
Avoid all that by just checking X86_FEATURE_IBPB_BRTYPE instead, which gets set by srso_select_mitigation() if the updated microcode exists.
Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation") Reviewed-by: Nikolay Borisov <nik.borisov@suse.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> --- arch/x86/kernel/cpu/bugs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index f081d26616ac..bdd3e296f72b 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2717,7 +2717,7 @@ static ssize_t srso_show_state(char *buf) return sysfs_emit(buf, "%s%s\n", srso_strings[srso_mitigation], - (cpu_has_ibpb_brtype_microcode() ? "" : ", no microcode")); + boot_cpu_has(X86_FEATURE_IBPB_BRTYPE) ? "" : ", no microcode"); } static ssize_t gds_show_state(char *buf) -- 2.41.0
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