Hi! I've tried passing through my ASUS Radeon HD7750, but qemu just hogs 100% of one core and stops. Since the display didn't light up, I couldn't see how far Win 7 boot went. For a Linux guest I tried redirecting kernel messages to serial console, but there was nothing (qemu stops even before kernel start?).
Also, this GPU is kinda troublesome: it doesn't work with the proprietary driver if VT-d is enabled in BIOS (boot process stops with "dmar: DRHD: handling fault status reg 3"). The GPU works with the FOSS driver, though. Could this somehow be related to the passthrough issue? Anyway, VT-d in pci-assign mode works for network adapters on this host. It runs kernel 3.9.0-rc5 (with vfio-vga enabled), qemu git from yesterday, and seabios 1.7.2. The host has no driver installed for the GPU. Before assiging it to qemu I'd run "echo '1002 683f' > /sys/bus/pci/drivers/vfio-pci/new_id" and the same for the associated HDMI device. Command line: qemu-kvm -machine q35,accel=kvm \ -cpu host -smp 4 -m 2G \ -vga none -display none \ -kernel /kvm/kernel-3.7.8 -append 'root=/dev/vda console=ttyS0' \ -drive index=0,media=disk,cache=none,if=virtio,aio=native,file=/dev/vg3/gpu \ -device vfio-pci,host=01:00.0,x-vga=on \ -device vfio-pci,host=01:00.1 \ -serial telnet:127.0.0.1:52990,server