Hi
At least in oVirt 4.3 I've made the experience that you still need the
ovirt-guest-agent and that qemu-guest-agent alone was not sufficient.
Additionally the agent in Debian 9 is to old and does not start on
oVirt 4.2 or newer if I remember correctly.
I've often taken the newer package from Debian 10 which works, but
others have also worked out workarounds.
This blog linked below looks ok, to me, at least this author is
correct about the device change from
/dev/virtio-ports/com.redhat.rhevm.vdsm
/dev/virtio-ports/ovirt-guest-agent.0 which the ovirt-guest-agent in
Debian 9 and older doesn't recognize out of the box:
https://angrysysadmins.tech/index.php/2019/02/bailey/debian-how-to-instal...
Regards
Mathieu