Vagrant/Virtual box error

I am trying to run 'vagrant up' on my RHEL VM and i get the following error. It looks like virtualization is not enabled.Any workaround for this ?

There was an error while executing VBoxManage, a CLI used by Vagrant for controlling VirtualBox. The command and stderr is shown below.

Command: ["startvm", "d7f1a56f-43bc-4cde-a3de-63bf5414ddd0", "--type", "headless"]

Stderr: VBoxManage: error: VT-x is not available (VERR_VMX_NO_VMX)
VBoxManage: error: Details: code NS_ERROR_FAILURE (0x80004005), component ConsoleWrap, interface IConsole

Since you're running host machine itself in virtual environment, make sure to expose virtualization flags. Check out the article for KVM and article for VMWare.