linux-kernel - Re: [PATCH] x86/CPU/AMD: Only apply Zenbleed fix for Zen2 during late microcode load

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <3C79F091-A19B-4BAD-8582-56961830AF25@alien8.de>
Date: Mon, 23 Sep 2024 18:02:28 +0200
From: Borislav Petkov <bp@...en8.de>
To: John Allen <john.allen@....com>, x86@...nel.org
CC: linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/CPU/AMD: Only apply Zenbleed fix for Zen2 during late microcode load

On September 23, 2024 5:41:12 PM GMT+02:00, John Allen <john.allen@....com> wrote:
>A problem was introduced with f69759b ("x86/CPU/AMD: Move Zenbleed check to

Use 12 chars for the commit id.

>the Zen2 init function") where a bit in the DE_CFG MSR is getting set after
>a microcode late load.
>
>The problem is that the microcode late load path calls into
>amd_check_microcode and subsequently zen2_zenbleed_check. Since the patch
>removes the cpu_has_amd_erratum check from zen2_zenbleed_check, this will

End all function names with "()".

>cause all non-Zen2 cpus to go through the function and set the bit in the
>DE_CFG MSR.
>
>Call into the zenbleed fix path on Zen2 cpus only.

s/cpus/CPUs/g

And yes, it should be cc:stable.

With all that addressed, you can add:

Acked-by: me

to the patch.

Thx.

-- 
Sent from a small device: formatting sucks and brevity is inevitable.