6.5-stable review patch. If anyone has any objections, please let me know.
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From: Josh Poimboeuf jpoimboe@kernel.org
[ Upstream commit a8cf700c17d9ca6cb8ee7dc5c9330dbac3948237 ]
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") Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Reviewed-by: Nikolay Borisov nik.borisov@suse.com Acked-by: Borislav Petkov (AMD) bp@alien8.de Link: https://lore.kernel.org/r/27d128899cb8aee9eb2b57ddc996742b0c1d776b.169388998... Signed-off-by: Sasha Levin sashal@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 f081d26616ac1..bdd3e296f72b0 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)