I was trying to create a lab enviroment to test Hyper-V high availability.
After confirming that I have enabled virtualisation of VT-x/EPT like in picture bellow
I have tried to install Hyper-V role. I succeded!!!
But, the problem appeared when tried to start virtual machine.
Error stated (Hyper-V error ID 20144)
The Virtual Machine Management Service failed to start the virtual machine '%machinename%' because one of the Hyper-V components is not running (Virtual machine ID %ID_of_the_virtual_machine%).
After reading a lot of docs there is one thing to do if you want to run nested VMs.
Edit VMX configuration file of virtual Hyper-V server and at the end add the following line:
hypervisor.cpuid.v0 = "FALSE"
Update (2.7.2013.): VMX configuration file is VMWARE Workstation configuration file for Virtual Machine runned under VMWare Workstation . It is located within folder (or directory or whatever you call it) where virtual HDDs of that VM are located. For examle, D:\VirtualMachines\Windows2008R2HyperV\. Under folder Windows2008R2HyperV, you should find VMX configuration file.
Machine must be turned off. After adding line, power on virtual Hyper-V server and everything will be ok.
You don't need to reinstall anything. You can reconfigure existing machine and make it work.
I think that VMWare should make this automatic.
Post me if it's not working or explanation is not clear.