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

[Alex Williamson]

On Sat, Mar 19, 2016 at 7:38 AM, Matthew Wolffsohn <mwolfie at 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
> ...snip...
>

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 at 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 at 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 at 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 at UnforseenCircumstances ~]# cat startvm.sh
> #!/bin/bash
>
> 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
>
> Sent from ProtonMail <https://protonmail.com>, Swiss-based encrypted
> email.
>
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>
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