linux-kernel - RE: [PATCH v4 16/36] x86/bugs: Restructure srso mitigation

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Message-ID:
 <LV3PR12MB9265D4474B492C8409776AD994B32@LV3PR12MB9265.namprd12.prod.outlook.com>
Date: Mon, 14 Apr 2025 21:12:31 +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>, Brendan Jackman <jackmanb@...gle.com>, Derek
 Manwaring <derekmn@...zon.com>
Subject: RE: [PATCH v4 16/36] x86/bugs: Restructure srso mitigation

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Josh Poimboeuf <jpoimboe@...nel.org>
> Sent: Thursday, April 10, 2025 12:39 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; Brendan Jackman
> <jackmanb@...gle.com>; Derek Manwaring <derekmn@...zon.com>
> Subject: Re: [PATCH v4 16/36] x86/bugs: Restructure srso mitigation
>
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
>
>
> On Mon, Mar 10, 2025 at 11:40:03AM -0500, David Kaplan wrote:
> > @@ -229,6 +226,8 @@ void __init cpu_select_mitigations(void)
> >       taa_update_mitigation();
> >       mmio_update_mitigation();
> >       rfds_update_mitigation();
> > +     /* srso_update_mitigation() relies on retbleed_mitigation. */
> > +     srso_update_mitigation();
>
> "relies on" -> "depends on" for consistency with the other comments.
> Also it's "retbleed_update_mitigation".  Also needs parentheses:

Ack.  I was referring to the variable here, but I can refer to the function which probably makes more sense given that is what is called here.

>
>         /* srso_update_mitigation() depends on retbleed_update_mitigation() */
>
> > +     switch (srso_mitigation) {
> > +     case SRSO_MITIGATION_SAFE_RET:
> > +             if (!IS_ENABLED(CONFIG_MITIGATION_SRSO))
> >                       pr_err("WARNING: kernel not compiled with
> MITIGATION_SRSO.\n");
>
> srso_mitigation should be reset to NONE here?
>
> > -             } else {
> > -                     pr_err("WARNING: kernel not compiled with
> MITIGATION_IBPB_ENTRY.\n");
>
> Same here.
>

Ack to both.

Thanks --David Kaplan