I have found some answer about Function level rest (FLR) info on the net.
... When it comes to peripheral I/O devices, there is no "special" virtualization feature that they need in order to work with PCI passthrough. What you need is to be able to reset them by software without resetting the entire system. This can mainly be done by function level reset (FLR) by which you can reset individual hardware components (or PCI devices, onboard components such as the NIC are also PCI devices) at the function level. ...
I don't know about ATI (or AMD) but Nvidia seems to be diligent to get it supported and they apparently supply firmware patches upon request for their Geforce cards. I've also read somewhere that their lines of Quadro and Tesla cards support FLR by default and are specifically designed to work with PCI/VGA passthrough.
http://www.tomshardware.com/forum/523-71-intel-homeCan TBS develop patch for their card, so this function can be included?