Hyper-V Update List for Windows Server 2008 R2
Microsoft has posted a comprehensive list of Hyper-V updates for Windows Server 2008 R2 that you should check it out if you work with Hyper-V.
The posted table shows the list of software updates and hotfixes for Hyper-V in Windows Server 2008 R2. Updates that are available on Windows Update are indicated, as well as the download location for those that are available at the Microsoft Download Center. These updates and hotfixes can help avoid some known issues and may save you a support call.
Keep in mind that some updates are required only under certain circumstances, as noted in the table provided by Microsoft.