I setup PCI passthrough in a virtual machine awhile back on Arch and it worked excellent! https://www.reddit.com/r/pcmasterrace/comments/3lno0t/gpu_pa...
The only issue I had was with my Oculus Rift, but I suspect I could have fixed it by getting a dedicated USB PCI card to passthrough. Anyways, for AAA games it worked wonderfully with very near native speeds.