Comment 26 for bug 1673467

The former came down to the difference of
none:
  <cpu>
    <topology sockets='1' cores='1' threads='1'/>
  </cpu>

host-model:
  <cpu mode='host-model'>
    <model fallback='allow'/>
    <topology sockets='1' cores='1' threads='1'/>
  </cpu>

host-passthrough:
  <cpu mode='host-passthrough'>
    <topology sockets='1' cores='1' threads='1'/>
  </cpu>