Questions of switching multiple Nvidia GPU cards between host and guest OS in Linux

We meets some problems when multiple GPU cards switch between host and guest OS in Linux.

  1. If we turn off one guest OS with GPU card, we could not trigger it again after the host OS insert Nvidia driver for another GPU card.
  2. If we would like to switch the GPU card between the guest and host OS, it would be failed after unload the host OS Nvidia driver.

We make some survey for this topic, and have someone do the samething.
https://github.com/jscinoz/optimus-vfio-docs
https://gist.github.com/Misairu-G/616f7b2756c488148b7309addc940b28

We would like to know is this (switch between host and guest OS) possible for vfio and native nvidia driver?
(Is there offical release information or documentation)
Or we may only use the methods as the previous link?
Please advise!
Thank you!
Cheers,
Edward Tseng