Nvidia proprietary driver on Dom0: swiotlb buffer is full

[Mathieu Tarral <mathieu.tarral@xxxxxxxxxxxxxx>]

Hi,

I'm trying to start Dom0 with the Nvidia proprietary driver v470,
on the latest Xen unstable from master, under Ubuntu 22.04.

Xen boots, but gdm3 doesn't start.

On reboot, by looking at journalctl -b 1 -e --dmesg, the following lines appear:

NVRM: loading NVIDIA UNIX x86_64 Kernel Module  470.129.06
...
nvidia 0000:65:00.0: swiotlb buffer is full (sz: 1011712 bytes), total 32768 
(slots), used 516 (slots)
NVRM: 0000:65:00.0: Failed to create a DMA mapping!
nvidia 0000:65:00.0: swiotlb buffer is full (sz: 413696 bytes), total 32768 
(slots), used 192 (slots)
NVRM: 0000:65:00.0: Failed to create a DMA mapping!
...

The driver works fine on Ubuntu's kernel (5.15.0-41-generic).

Any clue what's happening with Xen or the Nvidia driver ?

Note: nouveau works, but is painfully slow to refresh the screen.

Thanks !

Mathieu Tarral