Using GPU ports to different VMs - possible?

[iZak]

I just got working Proxmox VE 8.4 in my brand new Minisforum MS-A2 with Nvidia 3050 assigned to Win11 VM. After days of persist trying I still could not get AMD iGPU working for VMs but ordering and installing this additional 3050 card did the trick easily. Now Win11 VM works fine in different physical monitor than iGPU.

Now I was wondering that because there are 2 ports in this 3050 card (HDMI+DP) is it possible to assign proxmox VM1 to HDMI and VM2 to DP working at the same time?

To be able to do it I guess that I need 2 nvidia controllers listed in PCI listing but I can see only 1 nvidia gpu in PCI listing (which is now assigned for Win11 VM):

root@mylabserver8:~# lspci -nn | grep -i nvidia
08:00.0 VGA compatible controller [0300]: NVIDIA Corporation GA107 [GeForce RTX 3050 6GB] [10de:2584] (rev a1)
08:00.1 Audio device [0403]: NVIDIA Corporation GA107 High Definition Audio Controller [10de:2291] (rev a1)

In normal Win11 one can use 1st and 2nd port separately in different monitors. I was wondering that Is it possible at the same time somehow use similar manner in Proxmox the 1st port to VM1 and the VM2 to another monitor. I guess in this case igpu is still for proxmox console because I cannot get it work for VMs. Ideally it would be great to use iGPU to VM3 because I do not use proxmox system console to anything, I use webGUI only.

 

[groque]

It's not possible to assign different video ports (HDMI/DP) from the same GPU to different VMs, at least not with standard PCI passthrough or even with vGPU.

When you pass through a GPU in Proxmox, the entire GPU, including all display outputs, is dedicated to one VM. There’s no way to split HDMI to VM1 and DP to VM2.

Even with the recent vgpu_unlock breakthrough for RTX 30/40-series GPUs (see: r/Proxmox thread), the virtual functions created for vGPU don’t expose physical outputs. They're meant for headless remote rendering, not local monitors.

To get physical video output to multiple monitors from different VMs, the only clean option is to use multiple physical GPUs, each passed to its own VM.

 

[iZak]

It's not possible to assign different video ports (HDMI/DP) from the same GPU to different VMs, at least not with standard PCI passthrough or even with vGPU.

When you pass through a GPU in Proxmox, the entire GPU, including all display outputs, is dedicated to one VM. There’s no way to split HDMI to VM1 and DP to VM2.

Even with the recent vgpu_unlock breakthrough for RTX 30/40-series GPUs (see: r/Proxmox thread), the virtual functions created for vGPU don’t expose physical outputs. They're meant for headless remote rendering, not local monitors.

To get physical video output to multiple monitors from different VMs, the only clean option is to use multiple physical GPUs, each passed to its own VM.

Thanks for the explanation. I was suspecting that it is not possible but because multiple monitors with one card in the same hardware works in Windows and Linux only setup the issue is more a software issue than hardware (fw) issue. The ports can be assigned to different monitors but the platform drivers are not made for it, at least not now. Sometimes there are very sophisticated software solutions to these "problems" but not to this one yet.