Allowing live migration while parties other than the VM guest have write access to the shared directory requires special precautions, because any such party can remove, rename, or replace any file at any time, so we must at least be able to detect such cases.

We plan to implement such safeguards after we have single-writer live migration in place (https://issues.redhat.com/browse/RHEL-7383). We are planning to offer a file-handle-based solution, which requires CAP_DAC_READ_SEARCH.