Unfortunately AMD cards suffer from a reset bug, still, when used with passthrough.
The reset bug being that you can pass through the card fine, once. But if you try to pass it through again (or the card experiences an issue and needs to reset), they get caught in some kind of bad state and won’t work until power is removed and restored. Which requires a reboot or a only slightly less disruptive dance with system power states.
For vega and 5000 series gpu’s, there’s https://github.com/gnif/vendor-reset
Incidentally, nvidia gpus are so good at resetting, they’ve probably done so without you noticing. If the screen ever goes black for a fraction of a second and returns in normal usage, it was probably because it reset itself.
The lower 6000 series lower than the 6800’s for example may or may not have the issue. It seems most “reference” cards are fine, but custom vendor cards often but not always have issues. My reference 6700 works fine, but a sapphire 6700 probably won’t.
And the 7000 series is also fucky in a new way somehow. Gnif knows far more about this than me, and has basically thrown up his hands at how AMD doesn’t care. He’s made occasional posts about it on https://forum.level1techs.com/
Gnif is also responsible for Looking glass: https://github.com/gnif/LookingGlass
When it comes to splitting a gpu into virtual ones with SR-IOV/MxGPU, that’s not really a thing with AMD. Whereas Nvidia will happily give you what you want if you shovel some money into their gaping maw, AMD won’t even give business customers the time if day if you aren’t worth billions. They very deliberately do not want the unwashed masses to use MxGPU. See: https://www.reddit.com/r/VFIO/comments/eqvn9z/amd_mxgpu_or_s... for a summary of the years of hopelessness on this functionality.