Given is KDE / Plasma 5 with Leap 15.2 and 4 running VMs on the same host.

Requirement: 
On Shutdown or reboot via KDE, the VMs should be shutdown (and not suspend).
This has been working fine until Leap 15.1

Problem:
On shutdown via KDE or sddm, the VMs are suspended before the systemd service,
which previously started them, is called to shutdown them. The called "virsh
shutdown" in the systemd service just says, that the VM wouldn't run any more.

Analysis:
KDE and sddm seem to do a reboot / shutdown via "systemctl reboot / shutdown".
If I'm rebooting with "reboot" or "shutdown", the process works as expected
again: all VMs can be shutdown and are not suspended before.

Solutions:
Remove sddm and use kdm - kdm can be configured how to exactly execute restart
/ shutdown.

Questions:
- How can I configure KDE to use reboot / shutdown instead of systemctl
reboot... ?
or
- How can I block suspension of the VM in the XML definition of the VM (if a VM
uses a PCIE device via vfio, the VM refuses to suspend and can be shutdown
afterwards as usual via the existing systemd service)?
or
- Any other idea how to solve this problem?