Windows 2022 Server vms (and possibly others, I have only tested with Windows Server 2022), do not have the "blnsvr.exe" service installed as part of the migration process. This service is required to make memory usage statistics available for Windows VMs in the OpenShift UI. 

Specifically the "kubevirt_vmi_memory_used_bytes" (along with other kubevirt_vmi_memory" stats) are not available/populated unless the blnsvr.exe service is installed and running. 

This can be tested by doing the following:

1. migrate a windows server 2022 vm
2. ensure that the qemu-gest-agent is installed
3. Check the OpenShift Virtual Machine "metrics" tab, you will see that "Memory" shows "No data available"
4. query the "kubevirt_vmi_memory_used_bytes" from Prometheus to see that there is no data gathered for the windows virutal machine
5. Install the "blnsvr.exe" service by locating the file on the virtio.iso and run `blnsvr.exe -i` to install the service (i used https://fedorapeople.org/groups/virt/virtio-win/direct-downloads/archive-virtio/virtio-win-0.1.240-1/virtio-win.iso but I believe the openshift built in one also has this file ... or it should)
6. Reboot the Windows machine
7. You will now notice that "memory" information is now available including both in the UI as well as querying directly from prometheus with the "kubevirt_vmi_memory_used_bytes" query.

Note the balloon driver is installed as part of the migration, but the service that makes it usable is NOT installed.