Invalidating translation lookaside buffer entries in a virtual machine (VM) system

Abstract

One embodiment of the present invention is a technique to invalidate entries in a translation lookaside buffer (TLB). A TLB in a processor has a plurality of TLB entries. Each TLB entry is associated with a virtual machine extension (VMX) tag word indicating if the associated TLB entry is invalidated according to a processor mode when an invalidation operation is performed. The processor mode is one of execution in a virtual machine (VM) and execution not in a virtual machine. The invalidation operation belongs to a non-empty set of invalidation operations composed of a union of (1) a possibly empty set of operations that invalidate a variable number of TLB entries, (2) a possibly empty set of operations that invalidate exactly one TLB entry, (3) a possibly empty set of operations that invalidate the plurality of TLB entries, (4) a possibly empty set of operations that enable and disable use of virtual memory, and (5) a possibly empty set of operations that configure physical address size, page size or other virtual memory system behavior in a manner that changes the manner in which a physical machine interprets the TLB entries.

Description

BACKGROUND [0001] 1. Field of the Invention [0002] This invention relates to virtual machines. In particular, the invention relates to translation lookaside buffers that support a virtual-machine system. [0003] 2. Description of Related Art [0004] A virtual-machine system is a computer system that includes a virtual machine monitor (VMM) supporting one or more virtual machines (VMs). A Virtual Machine Monitor (VMM) is a software program that controls physical computer hardware and presents programs executing within a Virtual Machine (VM) with the illusion that they are executing on real physical computer hardware. Each VM typically functions as a self-contained platform, controlled by a “guest” operating system (OS), i.e., an OS hosted by the VMM, which executes as if it were running on a real machine instead of within a VM. [0005] To accomplish this simulation, it is necessary for some operations within a VM (e.g., attempts to configure device hardware) to be trapped and emulated b...

AI Technical Summary

Problems solved by technology

Because of this, system performance would suffer significantly if the TLB were invalidated on each such transition.

For this reason, a VM and its supporting VMM cannot easily share an address space.

If a VM

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