[w0utert]

I do this with QEMU/KVM with passthrough of an RTX 3090, an NVME SSD, and one of the onboard USB controllers. Works like a charm, though the VM boot time is very high if you allocate a lot of RAM to it (there's some kind of bottleneck in the linux kernel when pinning huge amounts of consecutive memory pages while using passthrough, don't fully understand it but it's a known problem).

Performance is indistinguishable from native, e.g. I can easily drive the screen at the max 144 Hz refresh rate, G-sync works, etc. I did put some effort in figuring out how to pin CPU threads to cores, optimize for the CPU core topology so Windows only gets cores on the same CCX (it's an AMD Zen 3, before that it was Zen 2), etc. But all of this is documented in many places.

Do note that depending on your motherboard not all of this is possible if the chipset & BIOS do not provide enough MMIO isolation, you might not be able to isolate a USB controller or a separate NVME drive, or you might get only half the PCIe lanes for the passthrough GPU if you need to use the other full-lane slot for something like a second GPU.

[simfoo]

I would pay good money for a ready to use distribution/setup that supports this incl. making sure it continues to work after updates

[w0utert]

The main problem would be to have to maintain the myriad of known working configurations, since they are all different depending on motherboard, BIOS, GPU, CPU, etc. If you are careful about picking the right parts (and assembling them properly), it's actually really easy to configure on any recent Linux distro, you can just click together the VM using virt-manager if you don't need anything special.

I know I had to jump through a lot of hoops to make it work though, my X470 motherboard didn't isolate the USB controller without a BIOS update for example, and after that the USB controller exhibited USB FLR (function level reset) problems causing it to hang the VM. This required blacklisting it's PCI ID from the Linux kernel and patching the kernel to disable FLR (fortunately these changes were later merged into the mainline kernel). I also had problems with the second GPU, if I plugged it into any slot other than the bottom x1 slot, the motherboard BIOS would reshuffle the IOMMU groups making it impossible to pass through the NVME and USB controller, or (if I put it in the second x16 slot) it would halve the PCIe bandwidth to the RTX3080.

All in all it took me the better part of a weekend to get everything working, but if I had to do it again from scratch and did some research into (in particular) the motherboard and BIOS, I would be able to set it everything up again in less than an hour.

[selfhoster11]

I was so disappointed that there is no such thing available that its just plug-and-go. It really feels like this setup is breaking ground for some reason.