Passthrough Asus 960 GTX to Windows 7 VM - Error code 43

[bavism]

Hi all, running into  some issues passing my 960 to a Windows 7 VM. It sounds like Windows 10 might give me better luck, but unfortunately I need Windows 7 to do some compatibility testing for work.

 

What I've tried:

• bios from techpowerup
• bios as dumped from https://github.com/SpaceinvaderOne/Dump_GPU_vBIOS/blob/master/dump_vbios.sh (interestingly, I could only dump the bios with this script when the GPU was set as the primary display GPU in my BIOS, but I've also heard that some cards flag a chance in the bios after they've been initialized which the drivers can look for to throw code 43)

 

• 960 gtx set as primary display in BIOS
• IGPU set as primary display in BIOS (on an i7-4770)

 

• 960 GTX set to bind to vfio on boot
• 960 GTX NOT set to bind to vfio on boot

 

• HyperV on/off

 

• Pass through both video and audio devices on the same bus/slot as a multifunction PCI device
• I'm using the 466.27 nvidia drivers in Windows 7 (curiously, sometimes if I uninstall the drivers, the first time I install them [before restarting] the driver doesn't report error 43, but programs relying on GPU don't run correctly, so I'm not actually sure if the GPU is fully enabled in those cases before the restart)
• I've got the hyperv vendor_id set to a 12 character string
• KVM hidden state is on

I've given almost every combination of the above choices a try, and still only get error 43 (verified via remote desktop, as I don't get any video out on the GPU).

 

Things I *haven't* tried:

• Q35 cpu type: I can't switch this without changing bus 0 to a pcie-root, but that seems to conflict with my main drive being a SATA drive, and I can't seem to get the drivers for a VirtIO drive to work in Windows 7 as they aren't signed (even with test signing on, and forcing signed driver requirement off)
• As mentioned before, a Windows 10 machine. I'd be interested to see if that works, but it won't help me get the machine I actually need up and running
• Older NVIDIA drivers?

 

Any thoughts folks?