Yesterday Microsoft released some patches for Windows Server 2012 and Windows 8. In this wave Microsoft also included some fixes for Hyper-V and also updated the Integration Services to a new version.
Old Hyper-V Integration Services Version: 6.2.9200.16384
New Hyper-V Integration Services Version: 6.2.9200.16433
To check which version is installed in your virtual machine you can use Windows PowerShell: Get Integration Services Version of Windows Server 2012 Hyper-V Virtual Machines.
So if you are running Windows Server 2008 R2 SP1 virtual machines or later don’t forget to update your Hyper-V Integration Services on those virtual machines. If you are running Windows Server 2012 virtual machines you can normally patch those via Windows Update or WSUS to get the latest Hyper-V integration services.
If you run Windows Server 2012 Cluster Aware-Updating you can us the Self-Service update feature to patch your Hyper-V Cluster automatically.