Qubes gpu passthru causes crash and restart

[apparatus]

Did you check it like this?

@taradiddles

Once you have rebooted, in dom0, type sudo lspci -vvn, you should see “Kernel driver in use: pciback” for the GPU you just hid.

What’s the value in the “Kernel driver in use:” for the GPU that you want to hide?
Maybe you didn’t hide it properly.