What were you trying to do that didn't work?

The source dev will be ignored for vhostuser + passt interface

What is the impact of this issue to you?

can not set the source dev for passt process

Please provide the package NVR for which the bug is seen:

libvirt-10.10.0-7.el9.x86_64

How reproducible is this bug?:

100%

Steps to reproduce

The <source dev/> setting will be ignored after "virsh define" or when you save after "virsh edit".

Details:
1. define vm with <source dev/> setting:

# cat rhel.xml | grep /interface  -B6
    <interface type='vhostuser'>
      <mac address='52:54:00:e2:ba:2c'/>
      <model type='virtio'/>
      <backend type='passt'/>
      <source dev='eno8303'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
    </interface>

# virsh define rhel.xml
Domain 'rhel' defined from rhel.xml

# virsh dumpxml rhel --xpath //interface
<interface type="vhostuser">
  <mac address="52:54:00:e2:ba:2c"/>
  <model type="virtio"/>
  <backend type="passt"/>
  <address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
</interface>

Expected results

The source dev should be valid in the interface setting, and passt should start with this parameter

Actual results

The source dev is ignored after xml validation