Radeon RX560 driver does not install on KVM guest

[John Bester]

System information:
Ubuntu 18.04 LTS (server edition) with kernel 4.15.0-47-generic x86_64

Software:
qemu-kvm:
  Installed: 1:2.11+dfsg-1ubuntu7.12

Hardware:
Motherboard: X370 Killer SLI
CPU: AMD Ryzen 7 1800X

PCI device:
26:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Baffin [Radeon RX 460/560D / Pro 450/455/460/555/560] (rev e5)
26:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Device aae0

This server has a Windows 10 pro guest OS which has two PCI devices passed
to it. This pass-through has worked fine for just over nine months after
a problem (launchpad bug 1781891) experienced when upgrading from Ubuntu 17.10.
Fortunately with the help of people responding the the bug report, the
problem was resolved.

Unfortunately after some upgrades (Windows guest upgrades, upgrade to RDP
server on Windows guest as well as apt upgrades on the host OS), the GPU
of the passed-through AMD RX560 was not used by the CAD system (BricsCAD
and BricsCAD shape) any more. The GPU was still listed on the task manager
under the Performance tab. In order to fix the problem, I uninstalled the
Radeon driver, downloaded the latest version and tried to install it. The
installation did not complete after several attempts, each time hanging the
Windows guest OS to the point where I had to reset the guest. I also tried
to re-install the older version (of which I kept the installer). Also note
that I had to use the cleanup application shipped with the AMD Radeon driver
and reboot before attempting a fresh install. During some of the attempts,
I had to remove the PCI devices from the guest in order to get Windows booting
again - at which time I have the opportunity to clean up the AMD drivers
before rebooting with PCI devices passed through again.

At this time I need instructions to get the proper logging for someone to
help me figure out where the problem is. So please advise on how to get
any relevant information. From a previous bug report, I was able to determine
a memory clash between host and client by issuing the following command:

grep -B 5 -A 5 "26[:]" /proc/iomem

However, at this point I am not getting any results. This may be because I
need to do this just after attempting a driver install. Please advise if this
is the case.

Any help would be greatly appreciated.