Q: Can I install Windows Server 2012 R2 Hyper-V Integration Services on a virtual machine and then run the virtual machine on a Windows Server 2012 Hyper-V server?

A: Although you can do this, I don't think it's a good idea—nor does Microsoft support it. If you do take this approach, you'll receive warnings in the event log that notify you of a network driver version mismatch. You should migrate your virtual machines from Windows Server 2012 Hyper-V to Windows Server 2012 R2 Hyper-V and then upgrade Integration Services.