[PATCH Part2 RFC v3 19/37] KVM: SVM: Add KVM_SNP_INIT command

[Brijesh Singh]

The KVM_SNP_INIT command is used by the hypervisor to initialize the
SEV-SNP platform context. In a typical workflow, this command should be the
first command issued. When creating SEV-SNP guest, the VMM must use this
command instead of the KVM_SEV_INIT or KVM_SEV_ES_INIT.

Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
 arch/x86/include/asm/svm.h |  2 ++
 arch/x86/kvm/svm/sev.c     | 18 ++++++++++++++++--
 include/uapi/linux/kvm.h   |  3 +++
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index b6f358d6b975..65407b6d35a0 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -212,6 +212,8 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 #define SVM_NESTED_CTL_SEV_ENABLE	BIT(1)
 #define SVM_NESTED_CTL_SEV_ES_ENABLE	BIT(2)
 
+#define SVM_SEV_FEATURES_SNP_ACTIVE		BIT(0)
+
 struct vmcb_seg {
 	u16 selector;
 	u16 attrib;
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index abca2b9dee83..0cd0078baf75 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -230,8 +230,9 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
 
 static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 {
+	bool es_active = (argp->id == KVM_SEV_ES_INIT || argp->id == KVM_SEV_SNP_INIT);
 	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
-	bool es_active = argp->id == KVM_SEV_ES_INIT;
+	bool snp_active = argp->id == KVM_SEV_SNP_INIT;
 	int asid, ret;
 
 	if (kvm->created_vcpus)
@@ -242,12 +243,16 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 		return ret;
 
 	sev->es_active = es_active;
+	sev->snp_active = snp_active;
 	asid = sev_asid_new(sev);
 	if (asid < 0)
 		goto e_no_asid;
 	sev->asid = asid;
 
-	ret = sev_platform_init(&argp->error);
+	if (snp_active)
+		ret = sev_snp_init(&argp->error);
+	else
+		ret = sev_platform_init(&argp->error);
 	if (ret)
 		goto e_free;
 
@@ -591,6 +596,9 @@ static int sev_es_sync_vmsa(struct vcpu_svm *svm)
 	save->pkru = svm->vcpu.arch.pkru;
 	save->xss  = svm->vcpu.arch.ia32_xss;
 
+	if (sev_snp_guest(svm->vcpu.kvm))
+		save->sev_features |= SVM_SEV_FEATURES_SNP_ACTIVE;
+
 	return 0;
 }
 
@@ -1523,6 +1531,12 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 	}
 
 	switch (sev_cmd.id) {
+	case KVM_SEV_SNP_INIT:
+		if (!sev_snp_enabled) {
+			r = -ENOTTY;
+			goto out;
+		}
+		fallthrough;
 	case KVM_SEV_ES_INIT:
 		if (!sev_es_enabled) {
 			r = -ENOTTY;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 3fd9a7e9d90c..f3a86d3a8f04 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1678,6 +1678,9 @@ enum sev_cmd_id {
 	/* Guest Migration Extension */
 	KVM_SEV_SEND_CANCEL,
 
+	/* SNP specific commands */
+	KVM_SEV_SNP_INIT = 255,
+
 	KVM_SEV_NR_MAX,
 };
 
-- 
2.17.1