We use virsh attach-device to hot-plug vhost-user nic with the following xml:

<interface type='vhostuser'>

  <mac address='52:54:01:3b:83:a5'/>

  <source type='unix' path='/var/run/vhost-user/port1' mode='client'/>

  <target dev='port1'/>

  <model type='virtio'/>

  <driver queues='4'/>

</interface>

We can successfully hot plug more than one vhost-user nics with

the same unix path ('/var/run/vhost-user/port1') which is a chardev backend.

However, only one nic attached can work, because the unix path can only pair with

one front-end of nic. So should we do something to forbid this operation?