[PATCH V11 3/5] KVM: SEV: Add support for SEV-ES intra host migration

Peter Gonda
2021-10-21T17:45:50Z

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: Tom Lendacky <thomas.lendacky@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 | 50 +++++++++++++++++++++++++++++++++++++++++-
1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 2c2f724c9096..d8ce93fd1129 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1605,6 +1605,48 @@ 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.
+ */
+ dst_vcpu->vcpu_id = src_vcpu->vcpu_id;
+ dst_svm->sev_es = src_svm->sev_es;
+ dst_svm->vmcb->control.ghcb_gpa =
+ src_svm->vmcb->control.ghcb_gpa;
+ dst_svm->vmcb->control.vmsa_pa = __pa(dst_svm->sev_es.vmsa);
+ dst_vcpu->arch.guest_state_protected = true;
+
+ memset(&src_svm->sev_es, 0, sizeof(src_svm->sev_es));
+ src_svm->vmcb->control.ghcb_gpa = 0;
+ src_svm->vmcb->control.vmsa_pa = 0;
+ 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;
@@ -1633,7 +1675,7 @@ 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;
}
@@ -1644,6 +1686,12 @@ 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);
--
2.33.0.1079.g6e70778dc9-goog