I'm using Kubevirt to manage my virtual machine instances. When I using Kubevirt to create a vm(with two GPUs), kubevirt will generate a libvirt guest domain xml for this vm which includes two GPUs, the domain xml as follow :

    <hostdev mode='subsystem' type='pci' managed='no'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x83' slot='0x00' function='0x0'/>
      </source>
      <alias name='ua-gpu-gpu0'/>
      <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='no'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x84' slot='0x00' function='0x0'/>
      </source>
      <alias name='ua-gpu-gpu1'/>
      <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
    </hostdev>

No one ever edit this domain xml, but these two hostdev element disappeared in the domain xml. During this time, I've run the gpu_burn command to do a stress test for these two GPUs.

My question is :

• when will libvirtd change the guest domain xml ?
• why libvirtd delete these two hostdev from domain xml ?