Re: [PATCH 0/2] Remove some hardcoded SEV-SNP guest policy checks during guest launch

[Sean Christopherson]

On Thu, 29 May 2025 16:17:58 -0500, Tom Lendacky wrote:
> This series removes some guest policy checks that can be better controlled
> by the SEV firmware.
> 
> - Remove the check for the SMT policy bit. Currently, a check is made to
>   ensure the SMT policy bit is set to 1. However, there is no reason for
>   KVM to do this. The SMT policy bit, when 0, is used to ensure that SMT
>   has been disabled *in the BIOS.* As this does not require any special
>   support within KVM, the check can be safely removed to allow the SEV
>   firmware to determine whether the system meets the policy.
> 
> [...]

Applied to kvm-x86 svm.  FWIW, I'm not entirely sure I love the idea of doing
nothing, e.g. it'd be nice to enumerate support to userspace.  But adding a
bunch of code to regurgitate information that's likely available to userspace
(or more likely, the platform admin/orchestrator) doesn't seem worthwile either.

I'll make sure to flag this for Paolo's eyeballs.

[1/2] KVM: SVM: Allow SNP guest policy disallow running with SMT enabled
      https://github.com/kvm-x86/linux/commit/9f4701e05fae
[2/2] KVM: SVM: Allow SNP guest policy to specify SINGLE_SOCKET
      https://github.com/kvm-x86/linux/commit/24be2b7956a5

--
https://github.com/kvm-x86/kvm-unit-tests/tree/next