RE: [PATCH v3 30/35] x86/bugs: Add attack vector controls for spectre_v2_user

[Kaplan, David]

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> Sent: Tuesday, February 11, 2025 1:03 PM
> To: Kaplan, David <David.Kaplan@xxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>; Borislav Petkov <bp@xxxxxxxxx>; Peter
> Zijlstra <peterz@xxxxxxxxxxxxx>; Pawan Gupta
> <pawan.kumar.gupta@xxxxxxxxxxxxxxx>; Ingo Molnar <mingo@xxxxxxxxxx>; Dave
> Hansen <dave.hansen@xxxxxxxxxxxxxxx>; x86@xxxxxxxxxx; H . Peter Anvin
> <hpa@xxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v3 30/35] x86/bugs: Add attack vector controls for
> spectre_v2_user
>
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>
> On Wed, Jan 08, 2025 at 02:25:10PM -0600, David Kaplan wrote:
> > @@ -1614,6 +1614,13 @@ spectre_v2_user_select_mitigation(void)
> >               spectre_v2_user_stibp = SPECTRE_V2_USER_STRICT;
> >               break;
> >       case SPECTRE_V2_USER_CMD_AUTO:
> > +             if (should_mitigate_vuln(X86_BUG_SPECTRE_V2_USER)) {
> > +                     spectre_v2_user_ibpb = SPECTRE_V2_USER_PRCTL;
> > +                     spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL;
> > +             } else {
> > +                     return;
> > +             }
> > +             break;
>
> Can just fallthrough in the should_mitigate_vuln() case?

Yeah, I can do that.

--David Kaplan

>
> >       case SPECTRE_V2_USER_CMD_PRCTL:
> >               spectre_v2_user_ibpb = SPECTRE_V2_USER_PRCTL;
> >               spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL;
>
> --
> Josh