How to test
- Start a windows guest with one PCI NICs (such as: 8139 model)
- Note the PCI slot numbers of the NIC in guest(my computer -> properties -> hardware -> the NIC properites).
- Shutdown the guest
- Add the 2th NIC (such as: e1000 model) and start the guest
- Check that the slot number of the 1th NIC hasn't changed, and guest is working fine.