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

[Kaplan, David]

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> Sent: Monday, February 10, 2025 5:44 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 09/35] x86/bugs: Restructure srbds mitigation
>
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>
> 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