Comment 0 for bug 1818854

---Problem Description---
The vfio-ap driver will create a matrix device in sysfs without a subsystem link. This triggers failures in libudev that might also lead to libvirt errors (e.g. see https://www.redhat.com/archives/libvir-list/2019-February/msg00837.html)

The proper fix is to add a subsystem link (e.g. by providing a dummy bus).

A fix for that is upstream in master branch already for kernel 5.1

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=36360658eb5a6cf04bb9f2704d1e4ce54037ec99

This need to be applied to Bionic, Cosmic and Disco