Confirmed:
if configure it hostpci0: 01:00 then it will just take first pci id and use that one.
-device vfio-pci,host=01:00.0,id=hostpci0,bus=pci.0,addr=10.0
Instead it needs to be:
-device vfio-pci,host=01:00.0,id=hostpci0,bus=pci.0,addr=10.0,multifunction=on \
-device...