GPU passthrough crashes host

[SunBlack]

I currently trying to passthrough a GPU to my VM.

System:
- Intel Xeon 2630v2 (no embedded GPU)
- 2x Nvidia 770 GTX

I performed a fresh installaion of proxmox 4.4 and followed this guide. If I now start a VM with GPU passthrough host is always crashing (even with a fresh created VM at first start, so before installation of any OS in this VM).

But there is a issue which I don't understand. I'm not able to get ROM of both VGAs (tried it direct after installation of Proxmox and after setting up passthrough):

root@proxmox:~# cd /sys/bus/pci/devices/0000:02:00.0/
root@proxmox:/sys/bus/pci/devices/0000:02:00.0# echo 1 > rom
root@proxmox:/sys/bus/pci/devices/0000:02:00.0# cat rom > ~/vbios.bin
cat: rom: Input/output error
root@proxmox:/sys/bus/pci/devices/0000:02:00.0# echo 0 > rom

Same happens with the other GPU (03:00.0). But this code works if I install Xen 7.2 on the system, so it is not a general hardware issue (with Xen 7.2 GPU passthrough works so far, expect a Code 43 issue, so I'm trying it again with proxmox). After extracting ROM with Xen worked I checked with rom-parser that both GPUs really support EFI and they do.

Any idea how to track down this issue (or any helpful logfile)?

//Edit: This time it worked (except getting ROM via proxmox)

 

[SunBlack]

Found the issue when host is crashing: Combining GPU passthrough with RAM balloning seems to be broken. Our system has 128GB memory. I have enabled balloning with 4GB at minimum and 128GB at maximum, so the VM can use all free memory. Without GPU passthrough Windows starts. With GPU passthrough host is crashing.