Need separate physical resources for security
Share single resources – security through hypervisor
There are different ways to implement a virtualized system. Para-virtualization is an excellent approach for retrofitting a scalable security solution into deployed embedded systems that are not due for additional hardware updates, but require a trusted execution environment.
Para-virtualization improves performance by optimizing the interaction of the OS and the hypervisor, but there is some effort required to customize the OSes. Hardware-assisted virtualization, once incorporated into a CPU,provides the benefits of improved virtualization performance with no modification of the guest operating systems required.