[PATCH Part2 v6 23/49] KVM: SVM: Add KVM_SNP_INIT command

[Ashish Kalra]

From: Brijesh Singh <brijesh.singh@xxxxxxx>

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.

The flags value must be zero, it will be extended in future SNP support to
communicate the optional features (such as restricted INT injection etc).

Co-developed-by: Pavan Kumar Paluri <papaluri@xxxxxxx>
Signed-off-by: Pavan Kumar Paluri <papaluri@xxxxxxx>
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
 .../virt/kvm/x86/amd-memory-encryption.rst    | 27 ++++++++++++
 arch/x86/include/asm/svm.h                    |  1 +
 arch/x86/kvm/svm/sev.c                        | 44 ++++++++++++++++++-
 arch/x86/kvm/svm/svm.h                        |  4 ++
 include/uapi/linux/kvm.h                      | 13 ++++++
 5 files changed, 87 insertions(+), 2 deletions(-)

diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
index 2d307811978c..903023f524af 100644
--- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
@@ -435,6 +435,33 @@ issued by the hypervisor to make the guest ready for execution.
 
 Returns: 0 on success, -negative on error
 
+18. KVM_SNP_INIT
+----------------
+
+The KVM_SNP_INIT command can be used by the hypervisor to initialize SEV-SNP
+context. In a typical workflow, this command should be the first command issued.
+
+Parameters (in/out): struct kvm_snp_init
+
+Returns: 0 on success, -negative on error
+
+::
+
+        struct kvm_snp_init {
+                __u64 flags;
+        };
+
+The flags bitmap is defined as::
+
+   /* enable the restricted injection */
+   #define KVM_SEV_SNP_RESTRICTED_INJET   (1<<0)
+
+   /* enable the restricted injection timer */
+   #define KVM_SEV_SNP_RESTRICTED_TIMER_INJET   (1<<1)
+
+If the specified flags is not supported then return -EOPNOTSUPP, and the supported
+flags are returned.
+
 References
 ==========
 
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 1b07fba11704..284a8113227e 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -263,6 +263,7 @@ enum avic_ipi_failure_cause {
 #define AVIC_HPA_MASK	~((0xFFFULL << 52) | 0xFFF)
 #define VMCB_AVIC_APIC_BAR_MASK		0xFFFFFFFFFF000ULL
 
+#define SVM_SEV_FEAT_SNP_ACTIVE		BIT(0)
 
 struct vmcb_seg {
 	u16 selector;
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index dc1f69a28aa7..813bda7f7b55 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -241,6 +241,25 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
 	sev_decommission(handle);
 }
 
+static int verify_snp_init_flags(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+	struct kvm_snp_init params;
+	int ret = 0;
+
+	if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data, sizeof(params)))
+		return -EFAULT;
+
+	if (params.flags & ~SEV_SNP_SUPPORTED_FLAGS)
+		ret = -EOPNOTSUPP;
+
+	params.flags = SEV_SNP_SUPPORTED_FLAGS;
+
+	if (copy_to_user((void __user *)(uintptr_t)argp->data, &params, sizeof(params)))
+		ret = -EFAULT;
+
+	return ret;
+}
+
 static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 {
 	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
@@ -254,13 +273,23 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 		return ret;
 
 	sev->active = true;
-	sev->es_active = argp->id == KVM_SEV_ES_INIT;
+	sev->es_active = (argp->id == KVM_SEV_ES_INIT || argp->id == KVM_SEV_SNP_INIT);
+	sev->snp_active = argp->id == KVM_SEV_SNP_INIT;
 	asid = sev_asid_new(sev);
 	if (asid < 0)
 		goto e_no_asid;
 	sev->asid = asid;
 
-	ret = sev_platform_init(&argp->error);
+	if (sev->snp_active) {
+		ret = verify_snp_init_flags(kvm, argp);
+		if (ret)
+			goto e_free;
+
+		ret = sev_snp_init(&argp->error);
+	} else {
+		ret = sev_platform_init(&argp->error);
+	}
+
 	if (ret)
 		goto e_free;
 
@@ -275,6 +304,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	sev_asid_free(sev);
 	sev->asid = 0;
 e_no_asid:
+	sev->snp_active = false;
 	sev->es_active = false;
 	sev->active = false;
 	return ret;
@@ -610,6 +640,10 @@ static int sev_es_sync_vmsa(struct vcpu_svm *svm)
 	save->xss  = svm->vcpu.arch.ia32_xss;
 	save->dr6  = svm->vcpu.arch.dr6;
 
+	/* Enable the SEV-SNP feature */
+	if (sev_snp_guest(svm->vcpu.kvm))
+		save->sev_features |= SVM_SEV_FEAT_SNP_ACTIVE;
+
 	return 0;
 }
 
@@ -1815,6 +1849,12 @@ int sev_mem_enc_ioctl(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/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index edecc5066517..2f45589ee596 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -72,6 +72,9 @@ enum {
 /* TPR and CR2 are always written before VMRUN */
 #define VMCB_ALWAYS_DIRTY_MASK	((1U << VMCB_INTR) | (1U << VMCB_CR2))
 
+/* Supported init feature flags */
+#define SEV_SNP_SUPPORTED_FLAGS		0x0
+
 struct kvm_sev_info {
 	bool active;		/* SEV enabled guest */
 	bool es_active;		/* SEV-ES enabled guest */
@@ -87,6 +90,7 @@ struct kvm_sev_info {
 	struct list_head mirror_entry; /* Use as a list entry of mirrors */
 	struct misc_cg *misc_cg; /* For misc cgroup accounting */
 	atomic_t migration_in_progress;
+	u64 snp_init_flags;
 };
 
 struct kvm_svm {
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 68ce07185f03..0f912cefc544 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1810,6 +1810,9 @@ enum sev_cmd_id {
 	/* Guest Migration Extension */
 	KVM_SEV_SEND_CANCEL,
 
+	/* SNP specific commands */
+	KVM_SEV_SNP_INIT,
+
 	KVM_SEV_NR_MAX,
 };
 
@@ -1906,6 +1909,16 @@ struct kvm_sev_receive_update_data {
 	__u32 trans_len;
 };
 
+/* enable the restricted injection */
+#define KVM_SEV_SNP_RESTRICTED_INJET   (1 << 0)
+
+/* enable the restricted injection timer */
+#define KVM_SEV_SNP_RESTRICTED_TIMER_INJET   (1 << 1)
+
+struct kvm_snp_init {
+	__u64 flags;
+};
+
 #define KVM_DEV_ASSIGN_ENABLE_IOMMU	(1 << 0)
 #define KVM_DEV_ASSIGN_PCI_2_3		(1 << 1)
 #define KVM_DEV_ASSIGN_MASK_INTX	(1 << 2)
-- 
2.25.1