[PATCH 2/4 V8] KVM: SEV: Add support for SEV-ES intra host migration

[Peter Gonda <pgonda@google.com>]

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 <pgonda@google.com>
Reviewed-by: Marc Orr <marcorr@google.com>
Cc: Marc Orr <marcorr@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 arch/x86/kvm/svm/sev.c | 53 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 6fc1935b52ea..321b55654f36 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1576,6 +1576,51 @@ 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 = dst->vcpus[i];
+		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.
+		 */
+		dst_vcpu->vcpu_id = src_vcpu->vcpu_id;
+		dst_svm->vmsa = src_svm->vmsa;
+		src_svm->vmsa = NULL;
+		dst_svm->ghcb = src_svm->ghcb;
+		src_svm->ghcb = NULL;
+		dst_svm->vmcb->control.ghcb_gpa = src_svm->vmcb->control.ghcb_gpa;
+		dst_svm->ghcb_sa = src_svm->ghcb_sa;
+		src_svm->ghcb_sa = NULL;
+		dst_svm->ghcb_sa_len = src_svm->ghcb_sa_len;
+		src_svm->ghcb_sa_len = 0;
+		dst_svm->ghcb_sa_sync = src_svm->ghcb_sa_sync;
+		src_svm->ghcb_sa_sync = false;
+		dst_svm->ghcb_sa_free = src_svm->ghcb_sa_free;
+		src_svm->ghcb_sa_free = false;
+	}
+	to_kvm_svm(src)->sev_info.es_active = false;
+
+	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;
@@ -1604,7 +1649,7 @@ 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;
 	}
@@ -1615,6 +1660,12 @@ int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
 	if (ret)
 		goto out_source_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, &to_kvm_svm(source_kvm)->sev_info);
 	kvm_for_each_vcpu (i, vcpu, source_kvm) {
 		kvm_vcpu_reset(vcpu, /* init_event= */ false);
-- 
2.33.0.309.g3052b89438-goog