Re: [PATCH 2/2] x86/cpu: Skip reading MSR_IA32_PLATFORM_ID in virtualized environment

Dave Hansen
2026-04-28T19:13:26Z

On 4/28/26 11:54, Edgecombe, Rick P wrote:
> From the series with the blamed commit:
> Today, the only code that cares about the platform ID is the microcode
> update code itself. To facilitate storing the platform ID in a more
> generic place and using it outside of the microcode update itself, put
> the enumeration into a helper function.
>
> But it is still only used for microcode stuff AFAICT... It seems it was just
> moved to be "consistent with the other fields which can be matched".

Right. The one place it is being queried is right next to the microcode
version being queried. The microcode version is a field in that info
structure, so the path of least resistance is to put the platform ID in
there too. It also just happened to fit in an existing hole so it
doesn't increase the size of the structure either.