Commit 179a8427 authored by Ashish Kalra's avatar Ashish Kalra Committed by Paolo Bonzini
Browse files

KVM: SEV: Disable SEV-SNP support on initialization failure 



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: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Co-developed-by: default avatarPratik R. Sampat <prsampat@amd.com>
Signed-off-by: default avatarPratik R. Sampat <prsampat@amd.com>
Reviewed-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: default avatarAshish Kalra <ashish.kalra@amd.com>
Reviewed-by: default avatarPankaj Gupta <pankaj.gupta@amd.com>
Reviewed-by: default avatarPavan Kumar Paluri <papaluri@amd.com>
Message-ID: <20250512221634.12045-1-Ashish.Kalra@amd.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ce360c2b

arch/x86/kvm/svm/sev.c

+35 −9
Original line number Diff line number Diff line
@@ -2871,6 +2871,33 @@ 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;
@@ -2975,6 +3002,14 @@ 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" :
@@ -3001,15 +3036,6 @@ 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)