KVM: SEV: Add support for SEV-ES intra host migration

For SEV-ES to work with intra host migration the VMSAs, GHCB metadata,
and other SEV-ES info needs to be preserved along with the guest's
memory.

Signed-off-by: Peter Gonda <[email protected]>
Reviewed-by: Marc Orr <[email protected]>
Cc: Marc Orr <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dr. David Alan Gilbert <[email protected]>
Cc: Brijesh Singh <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: Vitaly Kuznetsov <[email protected]>
Cc: Wanpeng Li <[email protected]>
Cc: Jim Mattson <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

arch/x86/kvm/svm/sev.c

@@ -1612,6 +1612,46 @@ static void sev_migrate_from(struct kvm_sev_info *dst,
 	list_replace_init(&src->regions_list, &dst->regions_list);
 }
 
+static int sev_es_migrate_from(struct kvm *dst, struct kvm *src)
+{
+	int i;
+	struct kvm_vcpu *dst_vcpu, *src_vcpu;
+	struct vcpu_svm *dst_svm, *src_svm;
+
+	if (atomic_read(&src->online_vcpus) != atomic_read(&dst->online_vcpus))
+		return -EINVAL;
+
+	kvm_for_each_vcpu(i, src_vcpu, src) {
+		if (!src_vcpu->arch.guest_state_protected)
+			return -EINVAL;
+	}
+
+	kvm_for_each_vcpu(i, src_vcpu, src) {
+		src_svm = to_svm(src_vcpu);
+		dst_vcpu = kvm_get_vcpu(dst, i);
+		dst_svm = to_svm(dst_vcpu);
+
+		/*
+		 * Transfer VMSA and GHCB state to the destination.  Nullify and
+		 * clear source fields as appropriate, the state now belongs to
+		 * the destination.
+		 */
+		memcpy(&dst_svm->sev_es, &src_svm->sev_es, sizeof(src_svm->sev_es));
+		dst_svm->vmcb->control.ghcb_gpa = src_svm->vmcb->control.ghcb_gpa;
+		dst_svm->vmcb->control.vmsa_pa = src_svm->vmcb->control.vmsa_pa;
+		dst_vcpu->arch.guest_state_protected = true;
+
+		memset(&src_svm->sev_es, 0, sizeof(src_svm->sev_es));
+		src_svm->vmcb->control.ghcb_gpa = INVALID_PAGE;
+		src_svm->vmcb->control.vmsa_pa = INVALID_PAGE;
+		src_vcpu->arch.guest_state_protected = false;
+	}
+	to_kvm_svm(src)->sev_info.es_active = false;
+	to_kvm_svm(dst)->sev_info.es_active = true;
+
+	return 0;
+}
+
 int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
 {
 	struct kvm_sev_info *dst_sev = &to_kvm_svm(kvm)->sev_info;
@@ -1640,7 +1680,7 @@ int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
 	if (ret)
 		goto out_fput;
 
-	if (!sev_guest(source_kvm) || sev_es_guest(source_kvm)) {
+	if (!sev_guest(source_kvm)) {
 		ret = -EINVAL;
 		goto out_source;
 	}
@@ -1660,10 +1700,16 @@ int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
 	if (ret)
 		goto out_dst_vcpu;
 
+	if (sev_es_guest(source_kvm)) {
+		ret = sev_es_migrate_from(kvm, source_kvm);
+		if (ret)
+			goto out_source_vcpu;
+	}
 	sev_migrate_from(dst_sev, src_sev);
 	kvm_vm_dead(source_kvm);
 	ret = 0;
 
+out_source_vcpu:
 	sev_unlock_vcpus_for_migration(source_kvm);
 out_dst_vcpu:
 	sev_unlock_vcpus_for_migration(kvm);