[vfio-users] VM doesn't boot, hangs with R9 Fury passthrough

[Matti Niemenmaa]

Hello all,

I'm trying to passthrough an AMD Radeon R9 Fury to a Windows 10 guest, 
but the VM doesn't seem to work at all when I tell qemu to add the 
vfio-pci device. No errors of any kind are output anywhere that I can see.

Possibly relevant hardware and software versions:

Motherboard: Asus X99-A
CPU:         Intel Core i7-5930k
GPU host:    AMD Radeon R9 270X
GPU guest:   AMD Radeon R9 Fury
Linux 4.1.6 (I also tried 4.2-rc8 with the same results)
QEMU 2.4.0
edk2.git-ovmf-x64-0-20150804.b1143.g8ca1489

The following command successfully boots the VM with emulated VGA 
graphics and working audio and networking (modulo some audio distortion, 
which I haven't bothered looking into yet):

qemu-system-x86_64
   -nodefconfig -serial none -parallel none -nodefaults -name The-Windows
   -enable-kvm -cpu host -smp sockets=1,cores=6,threads=2 -m 16G
   -soundhw hda
   -drive 
if=pflash,format=raw,readonly,file=.../edk2.git/ovmf-x64/OVMF_CODE-pure-efi.fd
   -drive if=pflash,format=raw,file=.../windows-ovmf-vars.fd
   -drive if=virtio,format=raw,file=.../windows.img,index=0,cache=none
   -rtc base=localtime
   -net nic,model=virtio -net bridge,br=br0
   -alt-grab
   -boot order=c
   -vga std

But replacing the last option, "-vga std", with the following, doesn't 
work at all as intended:

   -device vfio-pci,host=02:00.0,addr=06.0

The monitor the Fury is plugged into doesn't receive a signal, nor does 
anything show up in the window opened by qemu, so there's no visual 
feedback at all. It appears that Windows doesn't even start, since I 
can't connect to it over VNC despite that working when "-vga std" is 
used. As far as I can tell the VM hangs indefinitely at this point.

qemu doesn't report any errors (in fact it outputs nothing), nor is 
there anything relevant-looking in dmesg.

I'm at a loss as to how to proceed. Any assistance would be welcomed.

— Matti