[vfio-users] No video output from dedicated GPU when doing PCI passthrough

[Stano Lano]

AMD drivers dont like the GPU to be connected directly.
AMD GPUs should be connected through pcie-root-port like this:

    <controller type='pci' index='1' model='pcie-root-port'>
      <model name='ioh3420'/>
      <target chassis='1' port='0x1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01'
function='0x0' multifunction='on'/>
    </controller>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00'
function='0x0' multifunction='on'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x01' slot='0x00' function='0x1'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00'
function='0x1'/>
    </hostdev>

Some old drivers do work without the pcie-root-port

On Sun, Apr 16, 2017 at 3:28 PM, Elias Kosunen <elias.kosunen at gmail.com>
wrote:

> XML dump: https://pastebin.com/MFdqSV1F
> I haven't touched it by hand at all, it's all generated by virt-manager.
>
> I installed Windows and booted into it. Here's a screengrab of the Windows
> Device Manager: http://imgur.com/crC1lsd I was able to install the
> drivers for the first one ("Microsoft Basic Display Adapter") and after the
> installation its name changed to "MSI AMD R9 380" and its errors went away.
> For the others, it couldn't automatically find the drivers.
>
> For the "HID Button over Interrupt Driver", the status message was:
>   This device is not working properly because Windows cannot load the
> drivers required for this device (Code 31)
>   Object Name not found.
>
> And for the others it was the same:
>   The drivers for this device are not installed. (Code 28)
>
> According to Windows, the "PCI Device" is attached to PCI slot 10, "PCI
> Simple Communications Controller" to slot 7 and "Video Controller" to slot
> 12. Unfortunately, I was unable to figure out which devices these refer to.
>
>
> On 04/16/2017 02:49 PM, Marius Steffen wrote:
>
>> Could you please attach your virtual machine's config XML (output of
>> 'sudo virsh dumpxml <your_machine_name>')?
>> Also, Graphical Console is not available because you removed the QXL
>> controller and SPICE server. Please try reattaching them (SPICE, Tablet,
>> set video controller type to QXL) and keep your GPU attached.
>> Start into Windows 10 (you should be able to use the Graphical Console in
>> virt-manager now) and tell us/take a screenshot of Windows' device manager,
>> and possible errors it's showing regarding your GPU.
>>
>
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