I recently noticed another issue with AMD gpu passthrough. With my current config, in the guest the display tab is missing in adrenalin. As is hbcc settings. I found a potential fix on Reddit which is to implement the error 43 fix used for Nvidia cards. I’ll try it when I get home. But I wanted to get input from people here as I have not seen this issue mentioned before. Not being able to access hbcc options or freesync is a pretty big deal so I’m surprised that I’m only seeing one mention of the problem.
hmm… 
I have never taken a look at that (I didn’t need it for my purposes) might take a look when I get around to it.
What card are you using? Also, do you mind linking the reddit thread in question?
I’m using a vega 56. The display tab was working in bare metal initially. I can boot my vm to metal with my setup. I did that to set in my undervolt/overclock. then I was having some issues with the drivers in the vm so i removed them with DDU. after I reinstalled them the display tab disappeared.
here’s the thread in question https://www.reddit.com/r/VFIO/comments/9wqt3i/radeon_drivers_missing_display_tab/
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Thanks for the link.
hmm … everything seems to be there with my RX560
I hope someone else can provide some input, I’m not the best guy for that as I don’t do a lot with graphics cards. Thanks for pointing out the possible issue though, it just might help the next poor sod.
Just wanted to update on this. I added back the vendor id fixes people use for Nvidia, then I uninstalled the drivers using ddu and reinstalled them. Display tab is back and so is hbcc. However sometimes when I try to open adrenalin it acts like there isn’t a gpu there to access. Shutting down the VM and starting back up fixes this though.