Xen users - Oct 2013 - where can I find blktap driver?

Hi All,
I''m using RHEL6.4 and my kernel version is 
2.6.39-400.109.4.el6uek.x86_64. I have the following Xen version - 
4.1.30VM. I see that blktap kernel module is not present.
I want to load blktap module in my kernel. Where can I find blktap 
driver for the above kernel and Xen configuration?

Thanks in Advance,

Thanks,
Avinash.