Robin and Irvine [8] have introduced a procedure for the virtualization of x86 systems:
- Non-sensitive, non-privileged instructions: these can execute on the processor directly.
- Sensitive, privileged instructions: since the virtual machine runs in user mode on the CPU when it tries to run a privileged instruction it will cause the CPU to issue an interrupt. Then the VMM will trap that interrupt and execute all the steps required to emulate the instruction for that virtual machine.