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;
> +}
