linux-kernel - Re: Old microcode CPU matching issue - x86/microcode/intel: Refresh the revisions that determine old

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Message-ID: <85dd1e22-f629-4d2d-b572-30ca05ddab7a@intel.com>
Date: Fri, 14 Nov 2025 12:34:34 -0800
From: Dave Hansen <dave.hansen@...el.com>
To: Jon Kohler <jon@...anix.com>, Sohil Mehta <sohil.mehta@...el.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>, "x86@...nel.org"
 <x86@...nel.org>, Borislav Petkov <bp@...en8.de>,
 Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 "H . Peter Anvin" <hpa@...or.com>, Peter Zijlstra <peterz@...radead.org>,
 Josh Poimboeuf <jpoimboe@...nel.org>,
 Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
 Nikolay Borisov <nik.borisov@...e.com>,
 Alex Murray <alex.murray@...onical.com>,
 Andrew Cooper <andrew.cooper3@...rix.com>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Old microcode CPU matching issue - x86/microcode/intel: Refresh
 the revisions that determine old_microcode

On 10/22/25 10:53, Dave Hansen wrote:
> I think this is a platform mismatch problem. The microcode file for
> 06-8f-08 has two different versions for two different platforms:
> 
> 	$ iucode-tool --list-all intel-ucode/06-8f-08 
> 	...
> 	           sig 0x000806f8, pf_mask 0x10, 2025-04-08, rev 0x2c000401
> 	...
> 	           sig 0x000806f8, pf_mask 0x87, 2025-04-04, rev 0x2b000643
> 
> Note the pf_mask and rev deltas here:      ^^^^                  ^^^^^^^^^^
> 
> I guess we'll need to take those into consideration, both adding pf_mask to
> the match list and actually matching on it.

Jon,

Here is a completely untested series that might fix your issue:

https://git.kernel.org/pub/scm/linux/kernel/git/daveh/devel.git/log/?h=old-ucode-platform

It attempts to take IA32_PLATFORM_ID into account when considering
old microcode.