[Libguestfs] virt-p2v VM testing bitrot?

I've started looking into RHBZ 1590721 for virt-p2v. For p2v development, quick local testing is helpful. "make run-virt-p2v-directly" seems to be working great; however, the VM-based test methods seem to have developed problems, since I last looked. Namely: - "make run-virt-p2v-in-a-vm" boots quickly, but the GUI does not come up. - "make run-virt-p2v-in-an-nvme-vm" boots *incredibly slowly*. I checked, and the host CPU utilization during guest boot was around 20% (and KVM was enabled). I don't understand how or why, but exposing the "physical machine" disk over NVMe slows guest boot to a crawl -- it looks strangely "IO-bound". I don't recall this from the time I added this Makefile target! Do these symptoms look familiar? (For RHBZ 1590721, I think run-virt-p2v-directly will suffice; just wanted to record the above somewhere.) Thanks Laszlo