Re: [PATCH 0/6] [v2] x86/cpu: Take Intel platform into account for old microcode checks

[Maciej Wieczor-Retman]

Retested by fabricating the faulting scenario. After adding the patches the old
microcode warning didn't appear and the microcode entry was correctly matched.

Tested-by: Maciej Wieczor-Retman <maciej.wieczor-retman@xxxxxxxxx>

(resending due to lost in-reply-to)

On 2026-02-06 at 15:14:38 -0800, Dave Hansen wrote:
>Changes from v1:
> * Fix non-x86 PECI compile issues by lifting some x86 macros
>   into an arch-independent header.
> * Make intel_get_platform_id() match its name and return an ID,
>   not a mask.
> * Sort #includes
> * Move ->x86_platform_id comment
>
>The platform ID vs. platform mask confusion meant that v1
>worked by total accident. If you tested v1, I'd really
>appreciate you retest this as well.
>
>--
>
>There was a report[1] that CPUs running updated microcode were being
>reported as running old microcode. The reason is that the old
>microcode list neglects to take the platform ID into account.
>
>The platform ID is an Intel-only construct that allows CPUs that
>otherwise have the same model/family/stepping to take different
>microcode revisions. The microcode loader itself already checks this.
>Only the recent "old_microcode" checker failed here.
>
>Treat the platform ID as a peer of model/family/stepping. Store it
>in 'struct cpuinfo_x86', enable matching on it with with 'struct
>x86_cpu_id', and flesh out the 'old_microcode' list with it.
>
>This fixes the report of an inaccurate, false positive in the
>'old_microcode' vulnerability file.
>
>1. https://lore.kernel.org/all/38660F8F-499E-48CD-B58B-4822228A5941@xxxxxxxxxxx/
>
>Cc: Thomas Gleixner <tglx@xxxxxxxxxx>
>Cc: Ingo Molnar <mingo@xxxxxxxxxx>
>Cc: Borislav Petkov <bp@xxxxxxxxx>
>Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
>Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
>Cc: Tony Luck <tony.luck@xxxxxxxxx>
>Cc: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
>Cc: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
>Cc: x86@xxxxxxxxxx
>Cc: Jon Kohler <jon@xxxxxxxxxxx>

-- 
Kind regards
Maciej Wieczór-Retman