Re: [PATCH v9 31/43] x86/compressed/64: Add support for SEV-SNP CPUID table in #VC handlers

Borislav Petkov
2022-02-07T17:58:13Z

On Mon, Feb 07, 2022 at 09:37:39AM -0600, Michael Roth wrote:
> Absolutely, I know a thorough review is grueling work, and would never
> want to give the impression that I don't appreciate it. Was just hoping
> to revisit these in the context of v9 since there were some concerning
> things in flight WRT the spec handling and I was sort of focused on
> getting ahead of those in case they involved firmware/spec changes. But
> I realize that's resulted in a waste of your time and I should have at
> least provided some indication of where I was with these before your
> review. Won't happen again.

Thanks, that's appreciated.

And in case you're wondering, the kernel is the most flexible thing from
all parties involved so even if you have to change the spec/fw, fixing
the kernel is a lot easier than any of the other things. So make sure
you do a good job with the spec/fw - the kernel will be fine. :-)

> Ok, will work this in for v10. My plan is to introduce this struct:
>
> struct cpuid_leaf {
> u32 fn;
> u32 subfn;
> u32 eax;
> u32 ebx;
> u32 ecx;
> u32 edx;
> }

Ok.

> as part of the patch which introduces sev_cpuid_hv():
>
> x86/sev: Move MSR-based VMGEXITs for CPUID to helper
>
> and then utilize that for the function parameters there, here, and any
> other patches in the SNP code involved with fetching/manipulating cpuid
> values before returning them to the #VC handler.

Sounds good.

Thx.

--
Regards/Gruss,
Boris.