And you're thinking to yourself that the R9 Nano they used looks like a great choice for your own GPU assignment build, think again. This GPU is known to have reset issues, so while it's impressive to see a build with this degree of consolidation, you should be suspicious about the problems Linus alludes to and the limited functionality of the overall system shown in the video. For instance, does rebooting a VM require a host reboot, or perhaps a manual soft eject of the GPU from the VM? We see this a lot with newer AMD cards, well beyond the partial workarounds we have for Bonaire and Hawaii based GPUs.
Personally I would have preferred to see an NVIDIA based solution, but due to the scale of this build, and unique slot and power restrictions, the compatibility with GPU assignment was mostly an afterthought. NVIDIA is not without issues, but for the time being we understand those issues and have workarounds for them, and even a path for supported configurations with Quadro cards.
On the plus side, yes, this is using KVM and VFIO and it's an impressive example of what this technology can do. However, when you're spec'ing your own build, do your own research and don't rely on videos like this to choose your components. My 2 cents...