linux-kernel - Re: [PATCH] x86/bugs: Don't warn when overwriting retbleed_return_thunk with srso_return

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Message-ID: <20250515093652.GBaCW1tARiE2jkVs_d@fat_crate.local>
Date: Thu, 15 May 2025 11:36:52 +0200
From: Borislav Petkov <bp@...en8.de>
To: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Cc: Suraj Jitindar Singh <surajjs@...zon.com>, linux-kernel@...r.kernel.org,
	x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>, stable@...r.kernel.org
Subject: Re: [PATCH] x86/bugs: Don't warn when overwriting
 retbleed_return_thunk with srso_return_thunk

On Wed, May 14, 2025 at 04:30:22PM -0700, Pawan Gupta wrote:
> This was discussed during the mitigation, and pr_warn() was chosen because
> it was not obvious that srso mitigation also mitigates retbleed. (On a
> retrospect, there should have been a comment about it).

Why is that important?

We have multiple cases where a mitigation strategy addresses multiple attacks.

> The conclusion was to make the srso and retbleed relationship clear and
> then take care of the pr_warn().

So let's ask ourselves: who is really going to see what single-line warning?

What are we *actually* trying to prevent here?

How about a big fat splat at least if we're really trying to prevent something
nasty which causes a panic on warn...?

Thx.

-- 
Regards/Gruss,
    Boris.

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