On 5/12/2025 5:16 PM, Ashish Kalra wrote:
> From: Ashish Kalra <ashish.ka...@amd.com>
>
> 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.
>
> The platform may have SNP enabled but if SNP_INIT fails then SNP is
> not supported by KVM.
>
> During KVM module initialization query the SNP platform status to obtain
> the SNP initialization state and use it as an additional condition to
> determine support for SEV-SNP.
>
> Co-developed-by: Sean Christopherson <sea...@google.com>
> Signed-off-by: Sean Christopherson <sea...@google.com>
> Co-developed-by: Pratik R. Sampat <prsam...@amd.com>
> Signed-off-by: Pratik R. Sampat <prsam...@amd.com>
> Reviewed-by: Tom Lendacky <thomas.lenda...@amd.com>
> Signed-off-by: Ashish Kalra <ashish.ka...@amd.com>
Reviewed-by: Pavan Kumar Paluri <papal...@amd.com>
Thanks,
Pavan
> ---
> arch/x86/kvm/svm/sev.c | 44 +++++++++++++++++++++++++++++++++---------
> 1 file changed, 35 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index dea9480b9ff6..8c3b12e3de8c 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -2935,6 +2935,33 @@ void __init sev_set_cpu_caps(void)
> }
> }
>
> +static bool is_sev_snp_initialized(void)
> +{
> + struct sev_user_data_snp_status *status;
> + struct sev_data_snp_addr buf;
> + bool initialized = false;
> + int ret, error = 0;
> +
> + status = snp_alloc_firmware_page(GFP_KERNEL | __GFP_ZERO);
> + if (!status)
> + return false;
> +
> + buf.address = __psp_pa(status);
> + ret = sev_do_cmd(SEV_CMD_SNP_PLATFORM_STATUS, &buf, &error);
> + if (ret) {
> + pr_err("SEV: SNP_PLATFORM_STATUS failed ret=%d, fw_error=%d
> (%#x)\n",
> + ret, error, error);
> + goto out;
> + }
> +
> + initialized = !!status->state;
> +
> +out:
> + snp_free_firmware_page(status);
> +
> + return initialized;
> +}
> +
> void __init sev_hardware_setup(void)
> {
> unsigned int eax, ebx, ecx, edx, sev_asid_count, sev_es_asid_count;
> @@ -3039,6 +3066,14 @@ void __init sev_hardware_setup(void)
> sev_snp_supported = sev_snp_enabled &&
> cc_platform_has(CC_ATTR_HOST_SEV_SNP);
>
> out:
> + if (sev_enabled) {
> + init_args.probe = true;
> + if (sev_platform_init(&init_args))
> + sev_supported = sev_es_supported = sev_snp_supported =
> false;
> + else if (sev_snp_supported)
> + sev_snp_supported = is_sev_snp_initialized();
> + }
> +
> if (boot_cpu_has(X86_FEATURE_SEV))
> pr_info("SEV %s (ASIDs %u - %u)\n",
> sev_supported ? min_sev_asid <= max_sev_asid ?
> "enabled" :
> @@ -3065,15 +3100,6 @@ void __init sev_hardware_setup(void)
> sev_supported_vmsa_features = 0;
> if (sev_es_debug_swap_enabled)
> sev_supported_vmsa_features |= SVM_SEV_FEAT_DEBUG_SWAP;
> -
> - if (!sev_enabled)
> - return;
> -
> - /*
> - * Do both SNP and SEV initialization at KVM module load.
> - */
> - init_args.probe = true;
> - sev_platform_init(&init_args);
> }
>
> void sev_hardware_unsetup(void)
