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

Mon Jan 25 16:07:06 UTC 2016

Will, could you tell us the following?

What Linux distribution on host?
What kernel are you using on host?
What libvirt version on host?
What qemu version on host?
What OS on guest?
What nvidia graphics driver version on guest?

My machines gpu driver crashes constantly and I'm trying to narrow down
why. Thanks!

On Mon, Jan 25, 2016, 10:02 AM Will Marler <will at wmarler.com> wrote:

> This is discussed in
> http://vfio.blogspot.com/2015/05/vfio-gpu-how-to-series-part-4-our-first.html.
> You have to do more than <kvm><hidden state='on'/></kvm>:
>
> "The GeForce card is nearly as easy, but we first need to work around some
> of the roadblocks Nvidia has put in place to prevent you from using the
> hardware you've purchased in the way that you desire (and by my reading
> conforms to the EULA for their software, but IANAL).  For this step we
> again need to run virsh edit on the VM.  Within the <features> section,
> remove everything between the <hyperv> tags, including the tags
> themselves.  In their place add the following tags:
>
>     <kvm>
>       <hidden state='on'/>
>     </kvm>
>
> Additionally, within the <clock> tag, find the timer named hypervclock,
> remove the line containing this tag completely.  Save and exit the edit
> session."
>
> I can confirm it works, I've been getting a lot of mileage from my
> passed-through 750Ti lately since getting a Steam Link :-D.
>
> On Sun, Jan 24, 2016 at 7:32 AM, Ruben Felgenhauer <
> 4felgenh at informatik.uni-hamburg.de> wrote:
>
>> Hi,
>>
>> finally I had time to this again. I tried out virt-manager and after a
>> bit of playing around with it, it /somewhat/ worked:
>>
>> The machine is at least booting. I still have a standard vga card enabled
>> in the virt-manager config window.
>> After the machine has booted, I can see that the device gets recognized
>> as 750ti.
>> However, the gpu doesn't get used, because of 'Code 43'.
>> Code 43 is a generic error, so any idea what it could mean in this case?
>>
>> Of course I added the <kvm><hidden state='on'/></kvm> lines at the
>> associated position.
>>
>> Best regards,
>> Ruben
>>
>>
>> Am 18.01.2016 um 22:27 schrieb Will Marler:
>>
>> I'm not sure what correct command-line syntax is. Have you tried using
>> libvirt and VirtManager to handle your VM rather than command line, and
>> modifying the XML rather than the command line? I think that's generally
>> the preferred method these days (it's certainly easier from my point of
>> view, and the way I got my 750 Ti to pass through).
>>
>> On Mon, Jan 18, 2016 at 11:04 AM, 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) 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>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>
>>>> 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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>>>> vfio-users at redhat.com
>>>> https://www.redhat.com/mailman/listinfo/vfio-users
>>>>
>>>
>>>
>>>
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>>
>>
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