Rutger Helling <rhelling@mykolab.com> writes:

> In virt-manager when clicking "Add hardware" on a VM the USB/PCI Host
> Device boxes are greyed out with the message "Connection does not
> support host device enumeration". It seems we're missing some
> dependencies.

I don't have the solution, but I might have a work-around or two.

FYI, even though I also observe the problem you describe, it's actually
still possible to assign a PCI device to a VM by using virsh's
"attach-device" command.  See "man virsh" for details.  This requires
you to craft an XML file describing the device you wish to attach to
your VM [1].

In addition, if your goal is just to pass a USB device through to the
guest, you might try running virt-manager as root.  This has worked for
me in the past.

Of course, we should continue to investigate the actual problem.  I only
mention these work-arounds in the hopes that it helps you out.

Footnotes: 
[1]  https://libvirt.org/formatdomain.html

-- 
Chris