Unable to create or revert snapshots

[Larry Dewey]

With an update to Qemu (3.1.x) I am unable to revert snapshots using virt-manager or virsh. Virtual Machines existing before the update seem to function properly. It is only after creating a new machine that snapshots are misbehaving. I tested spinning up vms of tumbleweed, leap15, and ubuntu 18.04. Each of them had the following issues:

- With the machine running, live reversions act like they apply, but no changes are actually made.
- With the machine paused, reversion also does not apply.
- With the machine turned off, reversion is not possible. Virsh is unable to find the snapshot, and virt-manager errors out with:

Error running snapshot 'FreshInstall': internal error: qemu unexpectedly closed the monitor: 2019-01-15T19:19:46.020247Z qemu-system-x86_64: Device 'drive-virtio-disk0' does not have the requested snapshot 'FreshInstall'

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 75, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 111, in tmpcb
    callback(*args, **kwargs)
  File "/usr/share/virt-manager/virtManager/libvirtobject.py", line 66, in newfn
    ret = fn(self, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/domain.py", line 1105, in revert_to_snapshot
    self._backend.revertToSnapshot(snap.get_backend())
  File "/usr/lib64/python3.6/site-packages/libvirt.py", line 2024, in revertToSnapshot
    if ret == -1: raise libvirtError ('virDomainRevertToSnapshot() failed', dom=self)

libvirt.libvirtError: internal error: qemu unexpectedly closed the monitor: 2019-01-15T19:19:46.020247Z qemu-system-x86_64: Device 'drive-virtio-disk0' does not have the requested snapshot 'FreshInstall'

After doing some digging, the error occurs because of the following commit:
d98f26073bebddcd3da0ba1b86c3a34e840c0fb8

[Larry Dewey (larry-j-dewey)]

Adding System Information

[Larry Dewey (larry-j-dewey)]

Before kernel 4.20.x this was not an issue as nested virtualization was not enabled by default. In any distribution using 4.20.x or later, snapshots and migration do not work.

[Thomas Huth (th-huth)]

Can you still reproduce this issue with the latest version of QEMU and libvirt? Anyway, since the problem occurs with libvirt, have you already tried to report this issue to the libvirt project instead?

[Launchpad Janitor (janitor)]

[Expired for QEMU because there has been no activity for 60 days.]