[ovirt-users] Is it possible to disable qxl video?

Mon Jul 11 15:30:53 UTC 2016

On 11/07/16 17:16 +0200, Arman Khalatyan wrote:
>Yes I have a BusID inside the xorg.conf.
>I just tested with virt-manager and indeed it is not a ovirt failure.
>It is something to do with qemu-kvm + nvidia.
>I found here:https://wiki.debian.org/VGAPassthrough  that nvidia disables
>device when it is running on qemu-kvm is it still the case? to overcome
>that one need to set:
>
>-cpu host,kvm=off
>
>in the command line of qemu.

This applies to GPUs that NVIDIA does not support in virtualized
environments (actually your GTX630). Quadro K2200 and higher
(incl. grid, tesla) should not require masking the hypervisor. It
could be worth to supply dmesg from the host and from the guest so we
could see if there is any apparent failure.

That being said, I have had failures even with supported card that
just stopped at one point. It's worth trying the kvm=off trick.

>I was trying to convert virsh commands to qemu native, but it fails on
>Centos 7 :(
>virsh dumpxml > render.xml
>virsh  domxml-to-native qemu-argv render.xml
>error: internal error: invalid PCI passthrough type 'default'

I usually take the qemu command line from
/var/log/libvirt/qemu/${VM_NAME}, tweak it in vim and launch. Works
even for oVirt VMs (if you can hack around the storage).

>***********************************************************
>
> Dr. Arman Khalatyan  eScience -SuperComputing
> Leibniz-Institut für Astrophysik Potsdam (AIP)
> An der Sternwarte 16, 14482 Potsdam, Germany
>
>***********************************************************
>
>On Mon, Jul 11, 2016 at 11:55 AM, Martin Polednik <mpolednik at redhat.com>
>wrote:
>
>> On 11/07/16 09:46 +0000, Karli Sjöberg wrote:
>>
>>>
>>> Den 11 jul 2016 11:37 fm skrev Arman Khalatyan <arm2arm at gmail.com>:
>>>
>>>>
>>>> I just testing several GPUs with pci-passthrough: GTX630, Tesla 2050 and
>>>> FX5800.
>>>> None of them I got running with opengl/direct rendering inside the
>>>> virtual machine.
>>>> I was thinking something to do with qxl driver, but after blacklisting
>>>> it in the VMs kernel nothing was changed.
>>>> The VMs Xorg claiming always no display found even if I configure it
>>>> with headless option: nvidia-xconfig -a --use-display-device=None
>>>> --virtual=1280x1024
>>>> But with nvidia-smi I can see the GPU status, and I can run all cuda
>>>> tests where opengl/X11 is not involved.
>>>> My test system is CentOS 7 with ovirt 4.
>>>> BTW If I clone VM which was not running, to real host on bare metal,
>>>> everything is running as expecting.
>>>>
>>>
>>> Don't remember If this was mentioned but have you tried doing the same
>>> thing but with virt-manager on a standalone host, just to rule out oVirt
>>> from the equation?
>>>
>>
>> Also, the xorg must be setup to use the VFIO GPU. There is BusID
>> option in device section that must point to the guest address of the
>> GPU. I'm not sure if you've done that (and I'm quite sure it's missing
>> on the wiki, noted).
>>
>> [in the guest]
>> $ lspci | grep VGA
>> 03:00.0 VGA compatible controller: NVIDIA Corporation GM107GL [Quadro
>> K2200] (rev a2)
>>
>> and  using the address, add device section to /etc/X11/xorg.conf
>>
>> Section "Device"
>>    Identifier     "Device0"
>>    Driver         "nvidia"
>>    VendorName     "NVIDIA Corporation"
>>    BusID          "PCI:3:0:0"
>> EndSection
>>
>> That should allow xorg to use the assigned GPU.
>>
>> mpolednik
>>
>>
>> /K
>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ***********************************************************
>>>>
>>>>  Dr. Arman Khalatyan  eScience -SuperComputing
>>>>  Leibniz-Institut für Astrophysik Potsdam (AIP)
>>>>  An der Sternwarte 16, 14482 Potsdam, Germany
>>>>
>>>> ***********************************************************
>>>>
>>>> On Mon, Jul 11, 2016 at 9:06 AM, Martin Polednik <mpolednik at redhat.com>
>>>> wrote:
>>>>
>>>>>
>>>>> On 08/07/16 11:29 +0200, Michal Skrivanek wrote:
>>>>>
>>>>>>
>>>>>>
>>>>>> On 06 Jul 2016, at 14:06, Francesco Romani <fromani at redhat.com> wrote:
>>>>>>>
>>>>>>>
>>>>>>> From: "Arman Khalatyan" <arm2arm at gmail.com>
>>>>>>> To: "users" <users at ovirt.org>
>>>>>>> Sent: Monday, July 4, 2016 11:52:24 AM
>>>>>>> Subject: [ovirt-users] Is it possible to disable qxl video?
>>>>>>>
>>>>>>>
>>>>>>> Hi,
>>>>>>> I am doing PCI Passthrough for GPUs.
>>>>>>> Is it possible somehow to disable/remove default video qxl?
>>>>>>> thanks,
>>>>>>> Arman,.
>>>>>>> Hi,
>>>>>>>
>>>>>>> The 4.0 Vdsm allows you to run a headless VM, meaning a VM without
>>>>>>> graphic device/frontend.
>>>>>>> Not sure Engine allows you that however.
>>>>>>>
>>>>>>
>>>>>>
>>>>>> no it doesn’t
>>>>>>
>>>>>
>>>>>
>>>>> Even if engine allowed that, it may not be the correct solution.
>>>>>
>>>>> Running headless with PCI passthrough is considered primary VGA
>>>>> passthrough[1]. Using primary VGA passthrough without OVMF could cause
>>>>> (will cause) quite a bit of headaches.
>>>>>
>>>>> If you really want to try that, I assume using before_vm_start hook to
>>>>> remove the video device should be enough.
>>>>>
>>>>> [1] http://wiki.xenproject.org/wiki/Xen_VGA_Passthrough - it's
>>>>> possible to read about primary and secondary passthrough between the
>>>>> lines
>>>>>
>>>>> However, if QXL is the problem (why is that so?) then you can switch to
>>>>>> VGA(or CIRRUS if this is still 3.6)
>>>>>>
>>>>>> I'm afraid you will need to write a Vdsm hook.
>>>>>>>
>>>>>>> There could be simpler solutions depending on the Engine
>>>>>>>
>>>>>>> Bests,
>>>>>>>
>>>>>>> --
>>>>>>> Francesco Romani
>>>>>>> RedHat Engineering Virtualization R & D
>>>>>>> Phone: 8261328
>>>>>>> IRC: fromani
>>>>>>> _______________________________________________
>>>>>>> Users mailing list
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>>>>>>> http://lists.ovirt.org/mailman/listinfo/users <
>>>>>>> http://lists.ovirt.org/mailman/listinfo/users>
>>>>>>>
>>>>>>
>>>>>
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>>>>>
>>>>>
>>>>>
>>>>