Failed to acquire pid file ‘/var/run/libvirtd.pid’: Resource temporarily unavailable

参考：
https://blog.csdn.net/wuliangtianzu/article/details/109489649

或者
mv /var/run/libvirtd.pid /var/run/libvirtd.pid.backup

systemctl stop libvirtd

systemctl start libvirtd

mv /var/run/libvirtd.pid /var/run/libvirtd.pid.old

mv /var/run/libvirtd.pid.backup /var/run/libvirtd.pid

systemctl start libvirtd