The original implementation of the passt backend for vhost-user
interfaces erroneously forgot to parse:
<source dev='blah'/>
for interface type='vhostuser', so it wasn't being added to the passt
commandline, and also wasn't being saved to the domain config. Now we
parse it whenever the <backend> type='passt', no matter what the
interface type, and then throw an error during validation if
source/@dev was specified for interface type = 'user|vhostuser' and
backend type != 'passt'.
Fixes: 1e9054b9c79d721a55f413c2983c5370044f8f60
Resolves: https://issues.redhat.com/browse/RHEL-82539
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
4c979edaa5