Re: [PATCH v7 01/10] KVM: SEV: Disable SEV-SNP support on initialization failure

["Pratik R. Sampat" <prsampat@amd.com>]

Hi Tom,

On 2/24/2025 3:28 PM, Tom Lendacky wrote:
> On 2/21/25 15:01, Pratik R. Sampat wrote:
>> During platform init, SNP initialization may fail for several reasons,
>> such as firmware command failures and incompatible versions. However,
>> the KVM capability may continue to advertise support for it. Export this
>> information to KVM and withdraw SEV-SNP support if has not been
>> successfully initialized.
> 
> Hmmm... rather than creating a new API, can you just issue an
> SNP_PLATFORM_STATUS command and see if the SNP is not in the UNINIT state?
> 

Although reading sev->snp_initialized is probably cheaper to do, it is
cleaner to query the platform status.

Querying SNP_PLATFORM_STATUS requires the pages to transition to
firmware-owned and back, and the helpers for it are implemented within
sev-dev.c. So, similar to sev_platform_status(), I'm thinking it is
probably better to create the snp_platform_status() API as well and use
that within KVM to check the state.

Thanks!
Pratik