I'm having similar issue with A400 on xcp-ng8.3

Proprietary driver fails with following message when running nvidia-smi :

NVRM: GPU 0000:00:05.0: RmInitAdapter failed! (0x24:0x72:1568)
[ 44.619030] NVRM: GPU 0000:00:05.0: rm_init_adapter failed, device minor number 0
[ 45.095040] nvidia_uvm: module uses symbols nvUvmInterfaceDisableAccessCntr from proprietary module nvidia, inheriting taint.
[ 45.144703] nvidia-uvm: Loaded the UVM driver, major device number 241.

system is actually loading the driver :

[ 6.026970] xen: --> pirq=88 -> irq=36 (gsi=36)
[ 6.027485] nvidia 0000:00:05.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=none:owns=io+mem
[ 6.029010] NVRM: loading NVIDIA UNIX x86_64 Kernel Module 550.144.03 Mon Dec 30 17:44:08 UTC 2024
[ 6.063945] nvidia-modeset: Loading NVIDIA Kernel Mode Setting Driver for UNIX platforms 550.144.03 Mon Dec 30 17:10:10 UTC 2024
[ 6.118261] [drm] [nvidia-drm] [GPU ID 0x00000005] Loading driver
[ 6.118265] [drm] Initialized nvidia-drm 0.0.0 20160202 for 0000:00:05.0 on minor 1

xl pci-assignable-list gives :

0000:43:00.0
0000:43:00.1

and gpu is assigned as passthrough,, but when listing test VM i have empty list of devices..
[23:06 epycrep ~]# xl pci-list Avideo-nvidia
[23:35 epycrep ~]#

Not sure if i want to try more before switching gpu to something else. Any hint where to look for ?

Server is gigabyte g292-z20 wih epyc 7402p and single gpu for testing. IOMMU enabled.

Yes, though i could not access web appliance for whatever reason - it tuned out that local system drives for that host failed (raid controller (!) ) and it was giving this strange errors. maybe i'll start to boot those from FC

This shows up while trying to start vm that I updated (apt-get dist-upgrade).

But even more weird is the fact that after reverting to previous snapshot vm still gives the same error while trying to boot it. Any hint where to look for the issue?