HYPERVISOR CONTEXT SWITCHING USING A REDIRECTION EXCEPTION VECTOR 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.

主权项

1. A method of executing a context switch between hypervisor components in a computer system operable in more than two hierarchical privilege levels, comprising:
assigning a first component and a second component of a hypervisor to a first privilege level; setting a redirection exception vector at a second privilege level that is less privileged than the first privilege level; causing the first component to run one or more commands at a third privilege level that is less privileged than the second privilege level; while the first component is running the one or more commands at the third privilege level, determining that a first context switch from the one or more commands running at the third privilege level to the first component is to be performed and in response thereto, exiting the third privilege level and entering the second privilege level; in response to exiting the third privilege level, bouncing from the second privilege level to the first privilege level based on the redirection exception vector; configuring a state associated with the first privilege level; and executing the second component at the first privilege level.