A: If you've worked with virtualization for really any period, you know that one of its common requirements is processor-level virtualization extensions. These extensions-with names such as Intel VT or AMD-V-enable host processor features to operate correctly within the hypervisor.
Certain types of nested virtualization prior to the release of VMware Workstation 8 weren't possible because these virtualization extensions weren't passed into VMs by the hypervisor. For example, it wasn't possible to virtualize a copy of ESXi as an "outer" VM and then run a 64-bit OS within the "inner" VM.
With Workstation 8's virtual VT feature, this virtualization of 64-bit OSs in nested virtualization configurations becomes possible. To do so, you must first upgrade any older VM hardware versions to VMware hardware version 8. After you've upgraded hardware, view the properties for the VM's processors. In the properties settings, check the box titled Virtualize Intel VT-x/EPT or AMD-V/RVI.