Hyper-V support and Macbook Air 2013 i5? "Virtualization support is disabled in the firmware."

I have installed Windows 8 x64 Pro on a new Macbook Air 2013 (i5) using the Boot Camp. Everything seems to be working OK, but I'm not able to turn on the Hyper-V. Based on the forum posts, Hyper-V worked with the 2012 model. But on the 2013 model, I cannot turn on the feature as the Windows reports that "Hyper-V cannot be installed: Virtualization support is disabled in the firmware.".

I run the Coreinfo -v and it seems to report that the support is there:

Intel(R) Core(TM) i5-4250U CPU @ 1.30GHz

Intel64 Family 6 Model 69 Stepping 1, GenuineIntel

HYPERVISOR - Hypervisor is present

VMX * Supports Intel hardware-assisted virtualization

EPT * Supports Intel extended page tables (SLAT)

Any ideas?