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Re: [vfio-users] [help] Pci passthrough - I've probably done something really obvious wrong

On Sat, Mar 19, 2016 at 7:38 AM, Matthew Wolffsohn <mwolfie protonmail com> wrote:
Hi Vfio-users,

I'm trying to passthrough a single GPU (originally I was trying to passthrough two, but I have removed the other from the system to reduce the chance it could be causing a problem) to a standard Windows 8 VM.  Unfortunately upon starting the VM I get no output to either of my displays and the qemu output is spammed with dma errors such as below:

dma: command 78 not supported
dma: command 78 not supported
dma: command 80 not supported
dma: command 80 not supported
dma: command c8 not supported
dma: command c8 not supported
dma: command 80 not supported
dma: command 80 not supported
dma: command c8 not supported
dma: command c8 not supported
dma: command f8 not supported
dma: command c not supported
dma: command 84 not supported

These are not coming from vfio, they're generated by the i8257 dma controller in QEMU.
Let me run through some of the other specifics of my system.  I'm currently assigning the GPU to pci-stub using the grub commandline:
[root UnforseenCircumstances ~]# cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-linux-vfio root=UUID=8aa1247d-5b3c-4282-b666-d4000ff5a517 rw quiet splash resume=UUID=17129c2f-d322-4662-8bf5-d1ca010968e6 i915.enable_hd_vgaarb=1 intel_iommu=on pci-stub.ids=10de:1200,10de:0e0c

I am also attempting to use an Intel iGPU has the host's display, for that reason I'm trying to use the vga arbitration patch.  Strangely however, I still seem to have hardware accelleration on my iGPU - Shouldn't that be impossible due to the nature of the patch?
After booting I use the following command to rebind the gpu to vfio-pci:
[root UnforseenCircumstances ~]# cat bindcmd.txt
sudo /usr/bin/vfio-bind 0000:01:00.0 0000:01:00.1

I cannot use OVMF as my GPU is a Geforce 560 Ti, it has not UEFI ROM support so SeaBios is my only option.
[root UnforseenCircumstances ~]# lspci -nnk | grep NVIDIA
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GF114 [GeForce GTX 560 Ti] [10de:1200] (rev a1)
01:00.1 Audio device [0403]: NVIDIA Corporation GF114 HDMI Audio Controller [10de:0e0c] (rev a1)

Fermi cards don't have a great success record with device assignment for some reason.
And finally, as my GPU ROM won't play ball with me I'm using a downloaded ROM from TechpowerUp (For the same model!)
[root UnforseenCircumstances ~]# cat startvm.sh

qemu-system-x86_64 \
-enable-kvm -m 1024 -cpu host,kvm=off \
-smp 4,sockets=1,cores=4,threads=1 \
-device vfio-pci,host=01:00.0,x-vga=on,rombar=0,romfile=/root/gpurom.rom \

rombar=0 is clearly wrong, but I don't know if it's the source of your problems.
-device vfio-pci,host=01:00.1 \
-vga none \
-device virtio-scsi-pci,id=scsi \
-drive file=/home/mwolffsohn/kvm/win8.iso,id=isocd,format=raw,if=none -device scsi-cd,drive=isocd \
-drive file=/root/win.img,id=disk,format=qcow2,if=none,cache=writeback -device scsi-hd,drive=disk \
-drive file=/home/mwolffsohn/kvm/virtio-win.iso,id=virtiocd,if=none,format=raw -device ide-cd,bus=ide.1,drive=virtiocd

Hopefully I'm doing something really obvious wrong because this has been confusing me for ages!
Many thanks in advance,

-Matthew Wolffsohn

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