[SOLVED] PCI passthrough fails when HDMI display used

[dethegeek]

Hi

I'm setting up a virtual machine with a Nvidia GeForce 710 card.

A first try using the guide in the wiki succeeded with a VGA or / and DVI display. (reference : https://pve.proxmox.com/wiki/Pci_passthrough )

If I attempt to start the VM with a HDMI and/or DVI display the VM no longer send signal to my display a few seconds after the VM loaded the kernel. This happens way before Xorg loads, and I can avoid the issue with the kernel setting "nomodeset", but I can no longer use a descent resolution.

The VM idoes not crash or freeze : i can login and interact using SSH.

I think there is an issue with the pci passthrough because the HDMI audio card is not available in the VM, and the problem occurs only if I connect a HDMI display.

# lspci -k in the VM
(snip)
01:00.0 VGA compatible controller: NVIDIA Corporation GK208 [GeForce GT 710B] (rev a1)
    Subsystem: ZOTAC International (MCO) Ltd. GK208 [GeForce GT 710B]
    Kernel driver in use: nouveau
    Kernel modules: nouveau
(snip)

​

despite the host's settings

# lspci -k
(snip)
01:00.0 VGA compatible controller: NVIDIA Corporation Device 128b (rev a1)
    Subsystem: ZOTAC International (MCO) Ltd. Device 5360
    Kernel driver in use: vfio-pci
01:00.1 Audio device: NVIDIA Corporation GK208 HDMI/DP Audio Controller (rev a1)
    Subsystem: ZOTAC International (MCO) Ltd. Device 5360
    Kernel driver in use: vfio-pci
(snip)

​

Here is my VM configuration

agent: 1
bios: ovmf
bootdisk: scsi0
cores: 4
cpu: host
hostpci0: 01:00,pcie=1,x-vga=on
ide2: file=none,media=cdrom
machine: q35
memory: 4096
name: srv-pdi-01
net0: e1000=36:31:34:37:32:61,bridge=vmbr0
numa: 0
ostype: l26
smbios1: uuid=81134b13-b292-416a-b898-f77bc1f6a94c
sockets: 1
usb0: host=1631:5000
usb1: host=046d:c016
virtio0: file=local:108/vm-108-disk-1.qcow2,size=64G

What do you suggest to allow normal operation with HDMI ?

 

[dethegeek]

Hi

I fixed a typo in the config

hostpci0: 01:00.0,pcie=1,x-vga=on

is actually

hostpci0: 01:00,pcie=1,x-vga=on

(the first one was from a try to setup 2 passthrough : one per function of my graphic card.)

After many tries with various settings and also using args:

I found HDMI works fine only if I connect the HDMI monitor after guest's lightdm service started. I did not tried to plug the monitor earlier in the boot process.

I also notice the HDMI controller is stil not available in the guest.

I managed to show it only by configuring the passthrough with the following :

argd: -vga none -device vfio-pci,host=01:00.0,bus=pcie.0,addr=01.0,multifunction=on,x-vga=on -device vfio-pci,host=01:00.1,bus=pcie.0,addr=01.1

 

[dethegeek]

Hi

My issue seems to be related to Nouveau, and not to PCI passthrough.

Configuring the guest's OS to use Nvidia proprietary drivers instead Nouveau solved the issue.