linux-kernel - RE: [PATCH] x86/bugs: Restructure ITS mitigation

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Message-ID:
 <LV3PR12MB92655C23DF46F1F3B88139009490A@LV3PR12MB9265.namprd12.prod.outlook.com>
Date: Thu, 15 May 2025 21:15:59 +0000
From: "Kaplan, David" <David.Kaplan@....com>
To: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
CC: Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>,
	Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>,
	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] x86/bugs: Restructure ITS mitigation

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
> Sent: Thursday, May 15, 2025 4:12 PM
> To: Kaplan, David <David.Kaplan@....com>
> Cc: Thomas Gleixner <tglx@...utronix.de>; Borislav Petkov <bp@...en8.de>; Peter
> Zijlstra <peterz@...radead.org>; Josh Poimboeuf <jpoimboe@...nel.org>; 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] x86/bugs: Restructure ITS mitigation
>
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
>
>
> On Thu, May 15, 2025 at 08:47:56AM -0500, David Kaplan wrote:
> ...
> > +static void __init its_apply_mitigation(void) {
> > +     /* its=stuff forces retbleed stuffing and is enabled there. */
> > +     if (its_mitigation != ITS_MITIGATION_ALIGNED_THUNKS)
> > +             return;
> > +
> > +     if (!boot_cpu_has(X86_FEATURE_RETPOLINE))
> > +             setup_force_cpu_cap(X86_FEATURE_INDIRECT_THUNK_ITS);
> > +
> > +     setup_force_cpu_cap(X86_FEATURE_RETHUNK);
> > +     set_return_thunk(its_return_thunk);
> > +}
> > +
> >  #undef pr_fmt
> >  #define pr_fmt(fmt)     "Spectre V2 : " fmt
> >
> >
> > base-commit: 04bdd560124ec4d02d1d11ee3abc88d51954d7b8
>
> I am having trouble applying this patch to upstream and tip/master. I can't seem to
> find this base-commit in Linus's or tip tree. Please let me know what am I missing?

Hmm.  I was working off origin/master on tip.  This was the base commit in my git log from this morning:

commit 04bdd560124ec4d02d1d11ee3abc88d51954d7b8 (origin/master, origin/HEAD)
Merge: 61e94712bb24 e59236b5a09e
Author: Ingo Molnar <mingo@...nel.org>
Date:   Thu May 15 10:16:23 2025 +0200

Not sure if something happened to it since?  Or is there something else I can provide to help?

--David Kaplan