Comment 10 for bug 1851091

Unfortunately, I stumbled on this same problem.
What I see is that all but two Kernel configuration items are the same across multiple kernel versions. The two items that have changed are:

CONFIG_XEN_SELFBALLOONING=y (not sure why this has gone away)
CONFIG_XEN_TMEM=m

These two are missing in the 5.3.x kernels but XEN (Dom0) expects SELF_BALLOONING. I am limited in being able to experiment with this as most of my hardware is running Deb 9, 10 and Ubuntu 18.04. I have 19.10 running on a laptop that works with 5.0.0.xx and Xen.

Hope this helps. In the meantime, when I get a chance, I'll poke around on the laptop for more.