linux-kernel - [PATCH v3 6/7] KVM: SVM: Add support to initialize SEV/SNP functionality in KVM

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Message-ID: <14f97f58d6150c6784909261db7f9a05d8d32566.1735931639.git.ashish.kalra@amd.com>
Date: Fri, 3 Jan 2025 20:01:47 +0000
From: Ashish Kalra <Ashish.Kalra@....com>
To: <seanjc@...gle.com>, <pbonzini@...hat.com>, <tglx@...utronix.de>,
	<mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, <hpa@...or.com>, <thomas.lendacky@....com>,
	<john.allen@....com>, <herbert@...dor.apana.org.au>, <davem@...emloft.net>
CC: <michael.roth@....com>, <dionnaglaze@...gle.com>, <kvm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-crypto@...r.kernel.org>,
	<linux-coco@...ts.linux.dev>
Subject: [PATCH v3 6/7] KVM: SVM: Add support to initialize SEV/SNP functionality in KVM

From: Ashish Kalra <ashish.kalra@....com>

Remove platform initialization of SEV/SNP from PSP driver probe time and
move it to KVM module load time so that KVM can do SEV/SNP platform
initialization explicitly if it actually wants to use SEV/SNP
functionality.

With this patch, KVM will explicitly call into the PSP driver at load time
to initialize SEV/SNP by default but this behavior can be altered with KVM
module parameters to not do SEV/SNP platform initialization at module load
time if required. Additionally SEV/SNP platform shutdown is invoked during
KVM module unload time.

Signed-off-by: Ashish Kalra <ashish.kalra@....com>
---
 arch/x86/kvm/svm/sev.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 943bd074a5d3..0dc8294582c6 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -444,7 +444,6 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp,
 	if (ret)
 		goto e_no_asid;
 
-	init_args.probe = false;
 	ret = sev_platform_init(&init_args);
 	if (ret)
 		goto e_free;
@@ -2953,6 +2952,7 @@ void __init sev_set_cpu_caps(void)
 void __init sev_hardware_setup(void)
 {
 	unsigned int eax, ebx, ecx, edx, sev_asid_count, sev_es_asid_count;
+	struct sev_platform_init_args init_args = {0};
 	bool sev_snp_supported = false;
 	bool sev_es_supported = false;
 	bool sev_supported = false;
@@ -3069,6 +3069,16 @@ 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;
+
+	/*
+	 * NOTE: Always do SNP INIT regardless of sev_snp_supported
+	 * as SNP INIT has to be done to launch legacy SEV/SEV-ES
+	 * VMs in case SNP is enabled system-wide.
+	 */
+	sev_platform_init(&init_args);
 }
 
 void sev_hardware_unsetup(void)
@@ -3084,6 +3094,9 @@ void sev_hardware_unsetup(void)
 
 	misc_cg_set_capacity(MISC_CG_RES_SEV, 0);
 	misc_cg_set_capacity(MISC_CG_RES_SEV_ES, 0);
+
+	/* Do SEV and SNP Shutdown */
+	sev_platform_shutdown();
 }
 
 int sev_cpu_init(struct svm_cpu_data *sd)
-- 
2.34.1