Re: [PATCH 1/2] x86/microcode/AMD: Load late on both threads too

[Borislav Petkov]

On Wed, Aug 16, 2023 at 02:36:57PM -0700, Jim Mattson wrote:
> Doesn't this render that attestation misleading, since the microcode
> patch may not have been loaded on all logical processors?

For that it doesn't matter because the microcode engine is shared
between the two threads. The updated microcode revision is shown on any
of the two threads so you can load on one only. And we did this for
years.

Only recently we started loading on both and we will be doing that from
now on.

What could be problematic is if it simply fails loading on some cores
- regardless of SMT - but that would be problematic not only to SEV-SNP
attestation but to the general system health. tglx has some patches
which verify what has been successfully loaded where so hopefully we'll
be verifying more in that area.

HTH.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette