Hypervisor context switching using a trampoline scheme in processors having more than two hierarchical privilege levels

摘要

In a virtualized computer system operable in more than two hierarchical privilege levels, components of a hypervisor, which include a virtual machine kernel and virtual machine monitors (VMMs), are assigned to different privilege levels. The virtual machine kernel operates at a low privilege level to be able to exploit certain features provided by the low privilege level, and the VMMs operate at a high privilege level to support execution of virtual machines. Upon determining that a context switch from the virtual machine kernel to a VMM is to be performed, the computer system exits the low privilege level, and enters the high privilege level to execute a trampoline that supports context switches to VMMs, such as state changes, and then the VMM. The trampoline is deactivated after execution control is switched to the VMM.