Is there something else which is a prerequisite to
'qemu:commandline'
but if yes and I'm missing those, why would not then 'virsh' and/or
'virtqemud' say something?
No what you have looks ok, this is what I have as a test and is working ok. You can try
and these to see if something is shown in the guest.
<qemu:commandline>
<qemu:arg value='-cpu'/>
<qemu:arg value='host,hv_time,-hypervisor'/>
<qemu:arg value='-smbios'/>
<qemu:arg
value='type=0,vendor=LENOVO,version=FBKTB4AUS,date=07/01/2015,release=1.180'/>
<qemu:arg value='-smbios'/>
<qemu:arg
value='type=1,manufacturer=LENOVO,product=30AH001GPB,version="ThinkStation
P300",serial=S4M62281,uuid=1ecefe02-f1b6-4bf8-a925-c9f4ae512209,sku=LENOVO_MT_30AH,family=P300'/>
</qemu:commandline>
</domain>