I also got this:
NVRM: GPU 0000:01:00.0: RmInitAdapter failed! (0x11:0x45:2525]
NVRM: GPU 0000:01:00.0: rm_init_adapter failed, device minor number 0
while trying to pass a whole NVIDIA RTX 6000 Ada to an Ubuntu 20.04 VM under Proxmox.
But my simple solution was to set the so called display mode to “compute” with the displaymodeselector tool.
Then this GPU apparently also works without problems in the VM.
I’m writing this because the solution here sends me to the wrong track, apart from the fact that the vGPU User Guide gave me the crucial hint about the tool.
I don’t need a license and installation of vGPU video driver on the host and on the guest to passthrough the whole GPU.
Why this was never necessary for e.g. RTXA5000, is something I don’t understand.