Messages in this thread | | | From | Marc Orr <> | Date | Fri, 20 Aug 2021 14:00:57 -0700 | Subject | Re: [PATCH 2/2 V4] KVM, SEV: Add support for SEV-ES intra host migration |
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On Thu, Aug 19, 2021 at 8:49 AM Peter Gonda <pgonda@google.com> wrote: > > 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> > 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 | 58 +++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 55 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index 2d98b56b6f8c..970d75c34e9a 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -1554,6 +1554,53 @@ static void migrate_info_from(struct kvm_sev_info *dst, > list_replace_init(&src->regions_list, &dst->regions_list); > } > > +static int migrate_vmsa_from(struct kvm *dst, struct kvm *src) > +{ > + int i, num_vcpus; > + struct kvm_vcpu *dst_vcpu, *src_vcpu; > + struct vcpu_svm *dst_svm, *src_svm; > + > + num_vcpus = atomic_read(&dst->online_vcpus); > + if (num_vcpus != atomic_read(&src->online_vcpus)) { > + pr_warn_ratelimited( > + "Source and target VMs must have same number of vCPUs.\n"); > + return -EINVAL; > + } > + > + for (i = 0; i < num_vcpus; ++i) { > + src_vcpu = src->vcpus[i]; > + if (!src_vcpu->arch.guest_state_protected) { > + pr_warn_ratelimited( > + "Source ES VM vCPUs must have protected state.\n"); > + return -EINVAL; > + } > + } > + > + for (i = 0; i < num_vcpus; ++i) { > + src_vcpu = src->vcpus[i]; > + src_svm = to_svm(src_vcpu); > + dst_vcpu = dst->vcpus[i]; > + dst_svm = to_svm(dst_vcpu); > + > + 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;
Should we clear `src_svm->vmcb->control.ghcb_gpa`? (All the other fields in `srv_svm` that are copied are then cleared, except for this one.) Aside: Do we really need to clear all of the fields in `src_svm` after they're copied over? It might be worth adding a comment to explain why we're clearing them. It's not immediately obvious to me why we're doing that.
> + 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; > + } > + 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; > @@ -1565,7 +1612,7 @@ int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd) > if (ret) > return ret; > > - if (!sev_guest(kvm) || sev_es_guest(kvm)) { > + if (!sev_guest(kvm)) { > ret = -EINVAL; > pr_warn_ratelimited("VM must be SEV enabled to migrate to.\n"); > goto out_unlock; > @@ -1589,15 +1636,20 @@ 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; > pr_warn_ratelimited( > "Source VM must be SEV enabled to migrate from.\n"); > goto out_source; > } > > + if (sev_es_guest(kvm)) { > + ret = migrate_vmsa_from(kvm, source_kvm); > + if (ret) > + goto out_source; > + } > migrate_info_from(dst_sev, &to_kvm_svm(source_kvm)->sev_info); > - ret = 0; > + ret = 0;
nit: looks like there's some space issue on this line. Since I believe this line was introduced in the previous patch, I wouldn't expect it to show up with a diff in patch #2.
> out_source: > svm_unlock_after_migration(source_kvm); > -- > 2.33.0.rc1.237.g0d66db33f3-goog
This patch looks good overall to me.
Reviewed-by: Marc Orr <marcorr@google.com>
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