Re: [PATCH 1/8] x86/microcode/intel: Reject problematic loading on GNR systems

[Dave Hansen <dave.hansen@intel.com>]

On 9/1/26 16:16, Chang S. Bae wrote:
> Revision 0x1000405 contains internal microcode changes that are required
> by subsequent revisions to avoid #MC during loading. This dependency
> logically fits the minimum revision requirement.
> 
> The minimum revision check, however, currently applies only to the late
> loading path, since the dependency was primarily intended for OS-visible
> changes. The early loading path is therefore still vulnerable to this
> issue.

Honestly, I think minrevs are a distraction here. Let's keep this short
and sweet:

Microcode updates can usually jump revisions. However, there is an
erratum on Granite Rapids systems. If they "jump over" revision
0x1000405, they machine check <or whatever, I forget how they die>.

> Furthermore, one of the subsequent revisions does not correctly specify
> the minimum revision, so unfortunately the late loading cannot rely on
> that check either in this case.
> 
> Prevent loading 0x1000405 or later when the system has not yet been
> updated to 0x1000405 or later. Apply this blocking to both early- and
> late-loading paths.
> 
> Rename is_blacklisted() to is_late_loading_denied() so the new function
> that covers both loading paths is not confused with the late-load only
> one.

Whee, and get rid of a chunk of old terminology while we're at it.