referred from https://github.com/bushvin/zabbix-kvm-res

1. pip install libvirt-python
2. cp zabbix-kvm.py userparameter_zabbix-kvm.conf to /etc/zabbix/zabbix_agentd.d/
3. import zabbix kvm.xml into zabbix frontend.I work in zabbix 3.X,perhaps it will be some troble in importing to zabbix2.X frontend