linux-kernel - Re: Kernel 6.9 regression: X86: Bogus messages from topology detection

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Message-ID: <1e26effd-a142-44f5-9a72-90a823666d7c@leemhuis.info>
Date: Sat, 1 Jun 2024 09:06:51 +0200
From: "Linux regression tracking (Thorsten Leemhuis)"
 <regressions@...mhuis.info>
To: Thomas Gleixner <tglx@...utronix.de>,
 Peter Schneider <pschneider1968@...glemail.com>
Cc: LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
 stable@...r.kernel.org, regressions@...ts.linux.dev
Subject: Re: Kernel 6.9 regression: X86: Bogus messages from topology
 detection

On 31.05.24 10:42, Thomas Gleixner wrote:
> On Fri, May 31 2024 at 10:33, Thomas Gleixner wrote:

> ---
> Subject: x86/topology/intel: Unlock CPUID before evaluating anything
> From: Thomas Gleixner <tglx@...utronix.de>
> Date: Thu, 30 May 2024 17:29:18 +0200
> 
> Intel CPUs have a MSR bit to limit CPUID enumeration to leaf two. If this
> bit is set by the BIOS then CPUID evaluation including topology enumeration
> does not work correctly as the evaluation code does not try to analyze any
> leaf greater than two.
> [...]

TWIMC, I noticed a bug report with a "12 × 12th Gen Intel® Core™
i7-1255U" where the reporter also noticed a lot of messages like these:

archlinux kernel: [Firmware Bug]: CPU4: Topology domain 1 shift 7 != 6
archlinux kernel: [Firmware Bug]: CPU4: Topology domain 2 shift 7 != 6
archlinux kernel: [Firmware Bug]: CPU4: Topology domain 3 shift 7 != 6

Asked the reporter to test this patch. For details see:
https://bugzilla.kernel.org/show_bug.cgi?id=218879

Ciao, Thorsten

#regzbot fix: x86/topology/intel: Unlock CPUID before evaluating anything