GPU Passthrough Broken

I DIDN'T BREAK YOUR STUFF AND YOU HAVE NO PROOF.

 

 

Without diagnostics, not much anyone can do to help

I have found I get the same issue if I have i915 module loaded at boot time

 

VM has Nvidia k4000 passed thru (i440fx. not tried Q35.)

 

If has Seabios, will not boot black screen, 100% CPU on VM Core.

if has OVMF boots ok.

 

Created two VMs Q35 Seabios and Q35 OVMF. Same result as i440fx, seems to be an issue with SeaBios if i915 module is loaded at boot.

 

OVMF Ubuntu boots ok, SeaBios doesnt, both work ok if i915 not loaded.

Edited May 4, 2021 by SimonF

Found an old post(2014) about VGA Arbiter, I have tried answer 3 doesn't seem to make any difference. Suggests using OVMF if you are going to enable i915.

 

Question 3:

I have Intel host graphics, when I start the VM I don't get any output on the assigned VGA monitor and my host graphics are corrupted.  I also see errors in dmesg indicating unexpected drm interrupts.

Answer:

You're doing VGA assignment with IGD and have failed to apply or enable the i915 VGA arbiter patch.  The patch needs to be enabled with i915.enable_hd_vgaarb=1 on the kernel commandline.  See also my previous post about VGA arbitration and my previous post about using OVMF as an alternative to VGA assignment.

Question 4:

I have non-Intel host graphics and have a problem similar to Question 3.

Answer:

You need the other VGA arbiter patch.  This one is simply a bug in the VGA arbiter logic.  There are no kernel command line options to enable it.

Question 5:

I have Intel host graphics, I applied and enabled the i915 patch and now I don't have DRI support on the host.  How can I fix this?

Answer:

See my previous post about VGA arbitration to understand why this happens.  This is a know side-effect of enabling VGA arbitration on the i915 driver.  The only solution is to use a host graphics device that can properly opt-out of VGA arbitration or avoid VGA altogether by using a legacy-free guest.

Question 6:

How can I prevent host drivers from attaching to my assigned devices?

 

 

http://vfio.blogspot.com/2014/08/vfiovga-faq.html?m=0