Here is a short presentation about Xen hypervisor.
Barham, Paul, Boris Dragovic, Keir Fraser, Steven Hand, Tim Harris, Alex Ho, Rolf Neugebauer, Ian Pratt, and Andrew Warfield. “Xen and the art of virtualization.” In ACM SIGOPS Operating Systems Review, vol. 37, no. 5, pp. 164-177. ACM, 2003.