If the host (or service) where the libvirtd is running, is restarted, the connection from Jenkins will be lost. However, is expected to be reconnected and that is not happening. I have to manually restart Jenkins in order to regain the connection (there is no option to reconnect to libvirt host). This affects all the slaves in that host, no builds can be done in those slaves (if those slave are offline).

Log:
Getting connection to the virtual datacenter
org.libvirt.LibvirtException: cannot send data: Broken pipe
at org.libvirt.ErrorHandler.processError(Unknown Source)
at org.libvirt.Connect.processError(Unknown Source)
at org.libvirt.Connect.numOfDefinedDomains(Unknown Source)
at org.libvirt.Connect.listDefinedDomains(Unknown Source)
at hudson.plugins.libvirt.Hypervisor.getDomains(Hypervisor.java:146)
at hudson.plugins.libvirt.VirtualMachineLauncher.launch(VirtualMachineLauncher.java:99)
at hudson.slaves.SlaveComputer$1.call(SlaveComputer.java:200)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:679)