Re: [PATCH v2] x86/bugs: Warn when "ibrs" mitigation is selected on Enhanced IBRS parts

[Pawan Gupta]

On Thu, Jul 14, 2022 at 09:11:18PM -0300, Thadeu Lima de Souza Cascardo wrote:
> On Thu, Jul 14, 2022 at 04:15:35PM -0700, Pawan Gupta wrote:
> > IBRS mitigation for spectre_v2 forces write to MSR_IA32_SPEC_CTRL at
> > every kernel entry/exit. On Enhanced IBRS parts setting
> > MSR_IA32_SPEC_CTRL[IBRS] only once at boot is sufficient. MSR writes at
> > every kernel entry/exit incur unnecessary performance loss.
> >
> > When Enhanced IBRS feature is present, print a warning about this
> > unnecessary performance loss.
> >
> > Signed-off-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
>
> Reviewed-by: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxxxxx>

Thanks for the review.

Pawan