Enable nested virtualization on ESXi

 For ESXi 5.1

Kaedah 1:

Kaedah 2: 

1. Cleanly shutdown your VIRL virtual machine
2. Open the .vmx file with a text editor like Notepad++ or Text Wrangler
3. Ensure this line is present and value set to TRUE
   • vhv.enable = "TRUE"

ref: https://learningnetwork.cisco.com/s/article/t-shoot-kvm-ok-your-cpu-does-not-support-kvm-extensions