title: openstack create instance using specified xml file
body: <p>When I used openatck to add many ports to the VM, I found that the PCI bus would not be enough.
  So I need to modify the xml file of the VM through &quot;virsh edit&quot; command. But I have too many VMs to modify, is there any way to specify the xml file when creating the VM, or is there any openstack command to modify the xml file?</p>