linux-kernel - RE: [PATCH v3 09/35] x86/bugs: Restructure srbds mitigation

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Message-ID:
 <LV3PR12MB9265C0771729845CC02ADABC94FD2@LV3PR12MB9265.namprd12.prod.outlook.com>
Date: Tue, 11 Feb 2025 22:59:45 +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 09/35] x86/bugs: Restructure srbds mitigation

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Josh Poimboeuf <jpoimboe@...nel.org>
> Sent: Monday, February 10, 2025 5:44 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 09/35] x86/bugs: Restructure srbds mitigation
>
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
>
>
> On Wed, Jan 08, 2025 at 02:24:49PM -0600, David Kaplan wrote:
> > +static void __init srbds_apply_mitigation(void) {
> > +     if (!boot_cpu_has_bug(X86_BUG_SRBDS))
> > +             return;
>
> I realize this is just preserving the existing behavior, but for consistency with the
> others this should check for cpu_mitigations_off() so the mitigation doesn't get
> printed.

Yeah, we discussed this in v2 of the series.  I believe your preference was not to print anything if cpu_mitigations_off() but to print if a bug-specific mitigation was disabled (e.g., retbleed=off).  I see Boris was ok with that, so I guess we can go with that.

>
> >       update_srbds_msr();
> >       pr_info("%s\n", srbds_strings[srbds_mitigation]);
>
> More generally, IMO these should be printed in the select (or update) functions
> rather than in the apply functions.

Agreed.

--David Kaplan