Q: If I use Virtual Fibre Channel in Hyper-V with Windows Server 2012, does the Hyper-V host have to be zoned with access to the LUNs accessed by the virtual machines?
A: No. Virtual Fibre Channel adapters are added to virtual machines (VMS) and each Virtual Fibre Channel adapter has its own unique World Wide Port Name (WWPN) (as documented at Microsoft Technet).
The WWPN of the Virtual Fibre Channel adapter has to be zoned and given access to the storage. The Hyper-V host itself doesn't require any access, making this a very secure solution that differs from other virtualizaiton platforms where the host requires full access to any storage a VM needs access to.
You will notice that each Virtual Fibre Channel adapter actually has two WWPN's. This is so when a VM is moved between hosts, the VM running on the target host can use the second WWPN when it starts on the second host, avoiding the need to move the WWPN between adapters, which might cause a pause in connectivity.