linux-kernel - RE: [PATCH v3 30/35] x86/bugs: Add attack vector controls for spectre_v2

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Message-ID:
 <LV3PR12MB92656AC510522E800F93DFDE94FC2@LV3PR12MB9265.namprd12.prod.outlook.com>
Date: Wed, 12 Feb 2025 17:22:44 +0000
From: "Kaplan, David" <David.Kaplan@....com>
To: Josh Poimboeuf <jpoimboe@...nel.org>
CC: Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>,
	Peter Zijlstra <peterz@...radead.org>, Pawan Gupta
	<pawan.kumar.gupta@...ux.intel.com>, Ingo Molnar <mingo@...hat.com>, Dave
 Hansen <dave.hansen@...ux.intel.com>, "x86@...nel.org" <x86@...nel.org>, "H .
 Peter Anvin" <hpa@...or.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3 30/35] x86/bugs: Add attack vector controls for
 spectre_v2_user

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Josh Poimboeuf <jpoimboe@...nel.org>
> Sent: Tuesday, February 11, 2025 1:03 PM
> To: Kaplan, David <David.Kaplan@....com>
> Cc: Thomas Gleixner <tglx@...utronix.de>; Borislav Petkov <bp@...en8.de>; Peter
> Zijlstra <peterz@...radead.org>; Pawan Gupta
> <pawan.kumar.gupta@...ux.intel.com>; Ingo Molnar <mingo@...hat.com>; Dave
> Hansen <dave.hansen@...ux.intel.com>; x86@...nel.org; H . Peter Anvin
> <hpa@...or.com>; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v3 30/35] x86/bugs: Add attack vector controls for
> spectre_v2_user
>
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
>
>
> 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