I am trying to build a VFIO/PCI passthrough setup. I am currently using an NVidia GTX 1070 video card my for install. I am considering using the Intel GPU ( i6500 ) for day-to-day tasks and passing through the NVidia card to a virtual machine. I would like to keep it available for Linux as well, so I'm considering the following setup:

* Most desktop activities run using the integrated GPU
* (when needed) start a different Xorg instance bound to the NVidia GPU for Steam
* (when needed) start a KVM virtual machine bound the the NVidia GPU

The two final steps won't be done at the same time, but ideally this would be done without rebooting. I would be using the same monitor but with different cables, for instance HDMI for the iGPU and DisplayPort for the NVidia card. If needed I can whip up another mouse/keyboard pair.

Apparently my searching skills are inadequate for this topic, so my question is how can I configure my system for two Xorg instances - each using a different GPU?