On 01.07.2025 12:53, Andrew Cooper wrote:
> When support was originally introduced, ebx, ecx and edx were reserved and
> should have been zeroed in recalculate_misc() to avoid leaking into guests.
>
> Since then, fields have been added into ebx. Guests can't load microcode, so
> shouldn't see ucode_size, and while in principle we do want to support larger
> RAP sizes in guests, virtualising this for guests depends on AMD procuding any
> official documentation for ERAPS, which is long overdue and with no ETA.
>
> This patch will cause a difference in guests on Zen5 CPUs, but as the main
> ERAPS feature is hidden, guests should be ignoring the rap_size field too.
>
> Fixes: e9b4fe263649 ("x86/cpuid: support LFENCE always serialising CPUID bit")
> Signed-off-by: Andrew Cooper <[email protected]>
Reviewed-by: Jan Beulich <[email protected]>
I notice I have similar omissions in the respective AVX10.2 and KL patches.
Jan
