[vfio-users] VM doesn't boot if I use GPU passthrough

[Alexander Petrenz]

Hi Ruben,

lspci -k will show you which driver currently binds a device. The 'Kernel
driver in use' should be vfio-pci for all devices you want to pass through.
I don't use the options on the -device vfio-pci arguments anymore. I just
have -device vfio-pci,host=01:00.0 and -device vfio-pci,host=01:00.1. This
seems to be totally fine.

Regards
Alex


On Mon, Jan 18, 2016 at 7:04 PM, Ruben Felgenhauer <
4felgenh at informatik.uni-hamburg.de> wrote:

> Hi, Alex!
>
> Thanks for your reply!
> My GPU indeed has a seperate audio device located at 01:00.1.
>
> However, just adding -device vfio-pci,host=01:00.1 doesn't seem to do the
> trick.
> Of course the corresponding device is already blacklisted and bound to
> vfio.
>
> The Debian Wiki entry about VGA passthrough (
> <https://wiki.debian.org/VGAPassthrough>
> https://wiki.debian.org/VGAPassthrough) mentions QEMU arguments like
> "-device
> vfio-pci,host=01:00.0,bus=root.1,addr=00.0,multifunction=on,x-vga=on,romfile=...
> -device vfio-pci,host=01:00.1,bus=pcie.0" which seems to address GPUs with
> audio devices, but if I try to do something similar, the buses 'root' and
> 'pcie' couldn't be found. Maybe I missed something very important?
>
> On the same article, it says that the "HDMI soundcard [...] needs to be
> unbound from its driver":
> # echo '0000:01:00.1' | sudo tee
> /sys/bus/pci/devices/0000:01:00.1/driver/unbind
> I figured the vfio-bind script from the Arch Linux Forum thread (
> <https://bbs.archlinux.org/viewtopic.php?id=162768>
> https://bbs.archlinux.org/viewtopic.php?id=162768) would do exactly this
> thing, so I didn't explicitly do so for the audio device. Is that okay?
>
> Best regards,
> Ruben
>
> Am 18.01.2016 um 08:31 schrieb Alexander Petrenz:
>
> Hi Ruben,
>
> I guess your 750ti also has some audio device. You should pass through
> this too. It should be something like 01:00.1. There are many command line
> examples you can find about that.
> Also I´m not quite sure, if you should remove the x-vga=on.
>
> Regards
> Alex
>
> On Sun, Jan 17, 2016 at 11:12 PM, Ruben Felgenhauer <
> 4felgenh at informatik.uni-hamburg.de> wrote:
>
>> Hi,
>>
>> I am trying to pass my nVidia GTX 750ti to my QEMU guest.
>>
>> Problem is: After the QEMU monitor pops up, nothing happens. The GPU's
>> output is dead, and the vm won't be accessible via SSH anymore, so it's
>> very likely that the VM isn't booting up at all. Also, there are no error
>> messages from QEMU on the console whatsoever which makes debugging it
>> especially hard.
>>
>> This is how I start the vm with normal vga emulation:
>> qemu-system-x86_64 -hda vm.ovl -boot c -enable-kvm -m 1024 -cpu
>> host,kvm=off -smp cores=4,threads=2 -redir tcp:5022::22
>> Everything runs fine in this case. To do the passthrough, I add this:
>> -device vfio-pci,host=01:00.0,multifunction=on,x-vga=on -vga none
>> This brings said problems with it. I also tried out multiple different
>> combinations of -device's arguments or even adding a romfile for the GPU,
>> but none of these steps changed anything at all.
>>
>> Obviously, I am using a BIOS installation and I'm well-aware with this
>> bug: https://bugzilla.kernel.org/show_bug.cgi?id=107561, but neither
>> using less RAM (as you can see I am using 1GB now) nor switching to an
>> older Kernel changed anything about the problem. I have tried Kernel 4.1.0
>> and 4.3.0.
>>
>> Host is Debian testing with QEMU 2.5.0.
>> I tried both Debian and Windows 7 as a guest, but both are showing
>> exactly the same behaviour.
>> Mainboard is an ASUS Z87-PLUS. The 750ti is produced by ASUS aswell.
>>
>> Any idea how I could get passthrough running?
>>
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>>
>
>
>
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