Messages in this thread Patch in this message | | | Date | Tue, 11 Dec 2018 23:22:59 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/speculation: Add support for STIBP always-on preferred mode |
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On Tue, Dec 11, 2018 at 10:17:30PM +0000, Lendacky, Thomas wrote: > If using just SPECTRE_V2_USER_STRICT then the code in stibp_state() would > have to be able differentiate between the case where the mode was switched > because of X86_FEATURE_AMD_STIBP_ALWAYS_ON vs a kernel command line with > "spectre_v2_user=on". I could always set and use a static variable in the > file just for the stibp_state() case.
Does it matter on X86_FEATURE_AMD_STIBP_ALWAYS_ON CPUs?
I mean, we want STIBP to be always on there so you can do:
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 25e914f77bb8..d14860d1cf9c 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1089,7 +1089,10 @@ static char *stibp_state(void) case SPECTRE_V2_USER_NONE: return ", STIBP: disabled"; case SPECTRE_V2_USER_STRICT: - return ", STIBP: forced"; + if (boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON)) + return ", STIBP: always on"; + else + return ", STIBP: forced"; case SPECTRE_V2_USER_PRCTL: case SPECTRE_V2_USER_SECCOMP: if (static_key_enabled(&switch_to_cond_stibp)) so if user has booted with spectre_v2_user=on, we say, "oh well, it is always enabled anyway"... or?
> I'll give it a bit of time and see if there's any other discussion and > re-submit without the new SPECTRE_V2_USER_STRICT_PREFERRED value.
Sure.
-- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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