A lot of libvirt interactions with QEMU are via the QEMU monitor
console, which allows you to either query or modify the state of a
virtual machine. Spefici examples include: querying the status of live
block operations, live snapshot operations, live migration, etc.
Enabling the 'qemu_monitor' log filter allows us to capture precisely
what commands libvirt is sending to QEMU.
Note that the log level was intentionally set to '1' (i.e. debug) for
this specific filter, because (a) it's not extremely verbose, (b) when
something breaks, it's helpful to have the exact sequence of
interactions between libvirt and QEMU.
Change-Id: Iba95b6bd7c9f197c8d48c7d978f538e50d4e31fa
ae7b4f9b9e