kvm: Allow kvm_arch_get/put_registers to accept Error**

Julia Suvorovarequested to merge
jusual/centos-qemu-kvm:rhel-20574 into c10s

Merge Request Required Information

Jira: https://issues.redhat.com/browse/RHEL-20574

Applied without conflics.

Summary of Changes

There were a few bugs with silent cpu failures during migrations. The failures are no longer silent, but still indistinguishable, making diagnostics difficult.

This patchset reworks kvm_arch_get/put_registers to handle Error** and return a correct message.

Merge request reports