I don't know about other devices, but network cards have pretty good support for virtualization. A lot of them have virtual devices that the card generates and

I don't know about other devices, but network cards have pretty good support for virtualization. A lot of them have virtual devices that the card generates and are added to the system as if they were different PCI devices. Then, each VM gets one of those virtual devices and they access it directly as a regular PCI device, with no virtualization layer whatsoever.