Re: [PATCH v3] x86/bugs: Explicitly clear speculative MSR bits

[Borislav Petkov]

On Wed, Jan 11, 2023 at 11:00:37PM -0800, Pawan Gupta wrote:
> > SPEC_CTRL_RRSBA_DIS_S is a disable bit and I presume it needs to stay enabled.
> 
> The mitigation is enabled when this bit is set. When set, it prevents RET
> target to be predicted from alternate predictors (BTB). This should stay
> 0, unless enabled by a mitigation mode.
> 
> > Only when spec_ctrl_disable_kernel_rrsba() runs. And I'd say perf-wise it
> > doesn't cost that much...
> 
> I guess this doesn't matter now, because this patch is resetting it by
> default that keeps the mitigation disabled with no perf impact.

Ok, lemme queue it then.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette