1. Prepare a guest with the following xml
<interface type="user">
  <mac address="52:54:00:49:47:db"/>
  <model type="virtio"/>
  <address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
</interface>
<channel type="unix">
  <source mode="bind" path="/var/lib/libvirt/qemu/guestfwd"/>
  <target type="guestfwd" address="10.0.2.1" port="4600"/>
</channel>

...
-netdev {"type":"user","id":"hostnet0"} -device {"driver":"virtio-net-pci","netdev":"hostnet0","id":"net0","mac":"52:54:00:49:47:db","bus":"pci.1","addr":"0x0"}
...
-chardev socket,id=charchannel0,fd=22,server=on,wait=off -netdev {"type":"user","guestfwd":[{"str":"tcp:10.0.2.1:4600-chardev:charchannel0"}],"id":"channel0"}
...

# virsh detach-interface avocado-vt-vm1 user
Interface detached successfully

# virsh domiflist avocado-vt-vm1 
 Interface   Type   Source   Model   MAC
------------------------------------------

# virsh migrate avocado-vt-vm1 qemu+ssh://$target_hostname/system --live --p2p --verbose
Migration: [100.00 %]error: internal error: QEMU unexpectedly closed the monitor (vm='avocado-vt-vm1'): 2024-08-27T22:13:21.323269Z qemu-kvm: -device {"driver":"cirrus-vga","id":"video0","bus":"pcie.0","addr":"0x1"}: warning: 'cirrus-vga' is deprecated, please use a different VGA card instead
2024-08-27T22:13:21.326263Z qemu-kvm: warning: netdev channel0 has no peer
2024-08-27T22:13:29.213100Z qemu-kvm: Unknown savevm section or instance 'slirp' 1. Make sure that your current VM setup matches your saved VM setup, including any hotplugged devices
2024-08-27T22:13:37.319876Z qemu-kvm: load of migration failed: Invalid argument