This is supported by AMDVLK (as well as the NVIDIA proprietary driver). This can be useful for things like resource streaming and memory defragmentation.
It'd be good if RADV could add support for this as well.
FYI I've had a branch and posted patches for starting this on gfx8 and gfx9.
There are lots of corner cases and I hadn't resolved all the CTS tests on gfx9 I don't think.
I'm not sure when I'll loop back around to it, it would be good to have something more to test it with than CTS.