+svm break GPU passthrough (Error 43)

[mcdull]

I managed to set up win10 guest under PVE6.2 and wanted to host some emulator which requires nest virtualization.
After searching from forum, I need to add args: -cpu host,+svm in the conf file.
Then I reboot the GTX1080 stopped working. It still display video on screen but with like 640x480 resolution and the driver does not load (Error Code 43)

And I remove the line "args: -cpu host,+svm" fixed the issue and the video driver loaded and output with 4K resolution.

Is it a known issue that +svm cannot coexist with GPU passthrough?

(I have only 1 GPU in system, so the host is running headless)

Thank you.

 

[wolfgang]

Hi,

it makes no sense to use host +svm.
"host" means a lookup of your CPU that supports all flags that this CPU got.
So if you have a CPU that does not support svm it makes no sense to enable it.

 

[mcdull]

Sorry, I am new in Proxmox so I did not know exactly how all these works.
In reality with the same VM conf:-

args: -cpu 'host,+kvm_pv_unhalt,hv_vendor_id=NV43FIX,kvm=off,svm'
Boot okay with GPU work

args: -cpu 'host,+svm,kvm_pv_unhalt,hv_vendor_id=NV43FIX,kvm=off'
Boot okay with GPU not work

 

[wolfgang]

Great that it works now for you.