I have looked into this extensively, and all I can say is that it's extremely difficult to get working on certain hardware configurations if you only want to use one card, and even then it's hard to set everything up the way you want to do it.
Didn't have issues for almost a year.
Rule of the thumb for me is: AMD GPU for host, NVidia for guests. I use AMD GPUs for host because open source drivers are awesome and makes kernel/version updating easy. NVidia for guests is no brainer since they don't have PCIe reset issues. For motherboard, pick one that has good IOMMU groupings, usually x<3|4|5>70 for AM4 or x299 for Intel, or go Threadripper.
According to Wendell on Level1Linux, the reset bug should be fixed on AMD 6000 series gpus.