The API can be used to associate one or more (e.g. a RO and RW fd for a
disk backend image) FDs to a VM. They can be then used per definition.
The primary use case for now is for complex deployment where
libvirtd/virtqemud may be run inside a container and getting the image
into the container is complicated.
In the future it will also allow passing e.g. vhost FDs and other
resources to a VM without the need to have a filesystem representation
for it.
Passing raw FDs has few intricacies and thus libvirt will by default not
restore security labels.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>