開啓 libvirtd log 功能

# vi /etc/libvirt/libvirtd.conf

log_level = 1
log_filters="3:remote 4:event 3:json 3:rpc"
log_outputs="1:file:/var/log/libvirt/libvirtd.log"

# /etc/init.d/libvirt-bin restart 

References :
libvirt: Wiki: DebugLogs