linux-kernel - Re: [PATCH v3] x86: Clear feature bits disabled at compile-time

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Message-ID: <22wtxsixv54m6i5qkcp7x5xn22wg4sce7splenupcnpln4l7uw@szse2d653rxk>
Date: Thu, 24 Jul 2025 17:30:36 +0200
From: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
To: Borislav Petkov <bp@...en8.de>
CC: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	"Dave Hansen" <dave.hansen@...ux.intel.com>, <x86@...nel.org>, "H. Peter
 Anvin" <hpa@...or.com>, Kyung Min Park <kyung.min.park@...el.com>, Ricardo
 Neri <ricardo.neri-calderon@...ux.intel.com>, Tony Luck
	<tony.luck@...el.com>, <xin3.li@...el.com>, Farrah Chen
	<farrah.chen@...el.com>, <stable@...r.kernel.org>, Borislav Petkov
	<bp@...e.de>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] x86: Clear feature bits disabled at compile-time

On 2025-07-24 at 16:24:52 +0200, Borislav Petkov wrote:
>On Thu, Jul 24, 2025 at 12:59:47PM +0200, Maciej Wieczor-Retman wrote:
>> As I wrote in the v2 thread, based on what's in the documentation added at the
>> commit I pointed out, the behavior is a bug.
>
>That's all missing the whole idea of Fixes: tags and backports.
>
>Your patch must point to the correct faulty commit which causes this
>behavior or to none, which means backport everywhere. And I already
>explained this to you.

Okay, I guess I get it now. At first I tried to point at patches where each
feature was introduced. But that was not helpful to the stable team. In such
cases next time I'll just leave it at none and craft backports as you wrote
below.

>Pointing to a commit documenting this doesn't make the tree *before*
>that all of a sudden not affected.
>
>What I would do is, I'd go through all stable trees and check whether
>they're affected. If they are, you craft backports for all of them. You
>were already asking Greg what to do.
>
>But pointing to some innocuous commit and deciding that that is the
>culprit is not what you should do.
>
>Thx.

Thanks for explaining so thoroughly, I'll keep that in mind :)

>
>-- 
>Regards/Gruss,
>    Boris.
>
>https://people.kernel.org/tglx/notes-about-netiquette

-- 
Kind regards
Maciej Wieczór-Retman