Re: [PATCH] x86/cpufeatures: Cleanup AMD speculation feature bits
From: Borislav Petkov
Date: Fri Jan 26 2018 - 13:49:32 EST
On Fri, Jan 26, 2018 at 06:45:18PM +0000, David Woodhouse wrote:
> On Fri, 2018-01-26 at 19:41 +0100, Borislav Petkov wrote:
> > +#define X86_FEATURE_AMD_IBPBÂÂÂÂÂÂÂÂÂÂÂ(13*32+12) /* "" Indirect Branch Prediction Barrier MSR */
>
> Stray quotes.
No no, those quotes are magical. :)
They don't show the string in /proc/cpuinfo, see arch/x86/kernel/cpu/mkcapflags.sh
> > +#define X86_FEATURE_IBRSÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ(13*32+14) /* Indirect Branch Restricted Speculation */
>
> Please don't call it that. Call it X86_FEATURE_AMD_IBRS and leave
> X86_FEATURE_IBRS to parallel X86_FEATURE_IBPB as the *software* bit
> which is vendor-independent.
Do we have a X86_FEATURE_IBRS bit?
If so, then this bit should become
#define X86_FEATURE_AMD_IBRS (13*32+14) /* "" Speculation Control MSR only (AMD) */
*with* the magic quotes.
--
Regards/Gruss,
Boris.
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