Re: [PATCH v6 1/9] KVM: SEV: Disable SEV-SNP on FW validation failure

Sean Christopherson
2025-02-12T01:54:28Z

On Mon, Feb 03, 2025, Pratik R. Sampat wrote:
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 0f04f365885c..b709c2f0945c 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -3040,7 +3040,9 @@ void __init sev_hardware_setup(void)
> sev_es_asid_count = min_sev_asid - 1;
> WARN_ON_ONCE(misc_cg_set_capacity(MISC_CG_RES_SEV_ES, sev_es_asid_count));
> sev_es_supported = true;
> - sev_snp_supported = sev_snp_enabled && cc_platform_has(CC_ATTR_HOST_SEV_SNP);
> + sev_snp_supported = (sev_snp_enabled &&
> + cc_platform_has(CC_ATTR_HOST_SEV_SNP) &&
> + snp_fw_valid());
>
> out:
> if (boot_cpu_has(X86_FEATURE_SEV))
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index af018afd9cd7..b45cd60c19b0 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -122,6 +122,12 @@ static inline bool sev_version_greater_or_equal(u8 maj, u8 min)
> return false;
> }
>
> +bool snp_fw_valid(void)
> +{
> + return sev_version_greater_or_equal(SNP_MIN_API_MAJOR, SNP_MIN_API_MINOR);

This lacks any sense of abstraction. KVM doesn't care if the firmware is valid,
KVM only cares if SNP is support. KVM _must_ run after ASP initialization[*],
so I'm pretty sure KVM just needs a way to query sev->snp_initialized.

[*] https://lore.kernel.org/all/f78ddb64087df27e7bcb1ae0ab53f55aa0804fab.1739226950.git.ashish.kalra@amd.com