Caution: Hyper-V functionality inside VMware Fusion is experimental and is unsupported.
To change the guest OS type to Hyper-V:
Alternatively, you can edit the .vmx (virtual machine configuration) file of the Windows 8 virtual machine to override VMware Fusion's default virtual machine settings for running a hypervisor inside a virtual machine.
To edit the .vmx and override VMware Fusion settings:
hypervisor.cpuid.v0 = “FALSE”