Messages in this thread | | | Date | Fri, 10 Sep 2021 00:50:42 +0000 | From | Sean Christopherson <> | Subject | Re: [PATCH 2/3 V7] KVM, SEV: Add support for SEV-ES intra host migration |
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On Thu, Sep 02, 2021, Peter Gonda wrote: > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index 8db666a362d4..fac21a82e4de 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -1545,6 +1545,59 @@ 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");
Same comments about not logging the why.
> + return -EINVAL; > + } > + > + for (i = 0; i < num_vcpus; ++i) > + src_vcpu = src->vcpus[i];
This can be:
kvm_for_each_vcpu(i, src_vcpu, src) { if (!src_vcpu->arch.guest_state_protected) return -EINVAL;
} > + 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) {
And again here,
kvm_for_each_vcpu(i, src_vcpu, src) { src_svm = to_svm(src_vcpu);
> + src_vcpu = src->vcpus[i]; > + src_svm = to_svm(src_vcpu); > + dst_vcpu = dst->vcpus[i];
Probably a good idea to use kvm_get_vcpu(), even though dst->lock is held. If nothing else, using kvm_get_vcpu() may save some merge pain as there's a proposal to switch vcpus to an xarray.
> + dst_svm = to_svm(dst_vcpu); > + > + /* > + * Copy VMSA and GHCB fields from the source to the destination. > + * Clear them on the source to prevent the VM running and
As brought up in the prior patch, clearing the fields might ensure future KVM_RUNs fail, but it doesn't prevent the VM from running _now_. And with vcpu->mutext held, I think a more appropriate comment would be:
/* * Transfer VMSA and GHCB state to the destination. Nullify and * clear source fields as appropriate, the state now belongs to * the destination. */
> + * changing the state of the VMSA/GHCB unexpectedly. > + */ > + 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;
Let this poke out, an 83 char line isn't the end of the world, and not having the interrupt makes the code more readable overall.
> + src_svm->vmcb->control.ghcb_gpa = 0;
Nit, '0' isn't an invalid GPA. The reset value would be more appropriate, though I would just leave this alone.
> + 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; > +}
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