Re: [PATCH v3 2/9] KVM: selftests: Add a basic SNP smoke test

[Sean Christopherson]

On Wed, Oct 30, 2024, Pratik R. Sampat wrote:
> On 10/30/2024 8:46 AM, Sean Christopherson wrote:
> > +/* Minimum firmware version required for the SEV-SNP support */
> > +#define SNP_FW_REQ_VER_MAJOR   1
> > +#define SNP_FW_REQ_VER_MINOR   51
> > 
> > Side topic, why are these hardcoded?  And where did they come from?  If they're
> > arbitrary KVM selftests values, make that super duper clear.
> 
> Well, it's not entirely arbitrary. This was the version that SNP GA'd
> with first so that kind of became the minimum required version needed.
> 
> I think the only place we've documented this is here -
> https://github.com/AMDESE/AMDSEV/tree/snp-latest?tab=readme-ov-file#upgrade-sev-firmware.
> 
> Maybe, I can modify the comment above to say something like -
> Minimum general availability release firmware required for SEV-SNP support.

Hmm, so if AMD says SNP is only supported for firmware version >= 1.51, why on
earth is that not checked and enforced by the kernel?  Relying on userspace to
not crash the host (or worse) because of unsupported firmware is not a winning
strategy.