Hewlett-packard Development Company, L.p.

Todd J Kjos

Jonathan Kent Ross

Christophe De Dinechin

Gregg Bernard Lesartre

Gary Belgrave Gostin

Mark Edward Shaw

Craig William Warner

Guy Lowell Kuntz

Paul Bouchier

Bryan Stephenson

Richard Dickert Powers

Brian Matthew Johnson

Vipul Gandhi

Brendan A Voge

Ryan Lee Weaver

Glen Edwards

Leon Hong

In one embodiment of the present invention, a virtual-machine monitor detects entry and exit from guest-operating system code, storing the values of a set of high-order floating point registers in memory on entry, and restoring the values of the set of high-order floating point registers on exit. The virtual-machine monitor can then use the set of high-order floating point registers as scratch registers for emulation of guest-operating-system instructions. In alternative embodiments, a virtual-machine monitor obtains scratch registers for any code that the virtual-machine monitor can detect entry into and exit from, and for which a set of infrequently used registers can be identified, by storing the current contents of the set of registers upon detected entry into the code and restoring the original contents of the set of registers upon exit from the code.

Method for providing scratch registers for use by a virtual-machine monitor

Various embodiments of the present invention are directed to efficient methods by which virtual-machine monitors can introduce instructions into guest-operating-system code. In one embodiment of the present invention, the virtual-machine monitor builds instructions dynamically, at insertion time, using specified values for fields within the instruction. In one embodiment of the present invention, the instructions and instruction field values are stored in an instruction-block-representing data structure.

Method and system for replacing instructions and instruction blocks in computer code

A method for mapping an active entry within a virtually hashed page table is disclosed. An active entry within a virtually hashed page table is populated. A link table for locating a link at an offset from an active entry is maintained. This link table continues to be maintained as a valid link table until an occupied head bucket threshold is exceeded or a collision has occurred.

Mapping an active entry within a hashed page table

A computer system comprises a physical computer and a virtual machine monitor executable on the physical computer and configured to create an emulation of at least one guest operating system adapted to control the physical computer. The computer system further comprises a host executable on the physical computer that manages physical resources coupled to the physical computer on behalf of the virtual machine monitor and the at least one guest operating system. The host is adapted to virtualize a Peripheral Component Interconnect (PCI) configuration address space whereby the at least one guest operating system controls PCI input/output (I/O) devices directly and in absence of I/O emulation.

Partially virtualizing an I/O device for use by virtual machines

Various embodiments of the present invention are directed to efficient provision, by a virtual-machine monitor, of a virtual, physical memory interface to guest operating systems and other programs and routines interfacing to a computer system through a virtual-machine interface. In one embodiment of the present invention, a virtual-machine monitor maintains control over a translation lookaside buffer ('TLB'), machine registers which control virtual memory translations, and a processor page table, providing each concurrently executing guest operating system with a guest-processor-page table and guest-physical memory-to-physical memory translations. In one embodiment, a virtual-machine monitor can rely on hardware virtual-address-translation mechanisms for the bulk of virtual-address translations needed during guest-operating-system execution, thus providing a guest-physical memory interface without introducing excessive overhead and inefficiency.

Method for efficient virtualization of physical memory in a virtual-machine monitor

Various embodiments of the present invention are directed to methods by which a virtual-machine monitor can introduce branch instructions, in order to emulate privileged and other instructions on behalf of a guest operating system, into guest-operating-system code residing on virtually aliased virtual-memory pages. In a described embodiment of the present invention, the virtual-machine monitor physically aliases each virtual alias for a particular physical memory page by allocating a physical page for the virtual alias, copying the original contents of the physical memory page to the allocated physical page, or physical alias page, and subsequently patching each physical alias page appropriate to the physical address of the physical alias page.

Method for patching virtually aliased pages by a virtual-machine monitor

A partitionable computer system and method of operating the same is disclosed. The partitionable computer system has a state machine, a processor, and a device controller. The state machine can be configured to monitor the status of a partition of the partitionable computer system. The information provided by the state machine can be used to provide security within the partitionable computing system.

Security measures in a partitionable computing system

A software monitor, interposed between the hardware layer of a computer system and one or more guest operating systems, constructs and maintains a guest-physical-address-to-host-physical-address map for each guest operating system, and maintains a virtual memory addressing context for each guest operating system that may include a virtual-hash-page table for each guest operating system, the contents of translation registers for each guest operating system, CPU-specific virtual-memory translations for each guest operating system, and the contents of various status registers. The monitor runs at the highest privilege level provided by the hardware system, intercepting attempts to execute privileged instructions by guest operating systems, and simulates or enhances certain of the privileged instructions related to virtual-memory addressing in order to construct and maintain the guest-physical-address-to-host-physical-address map and to provide each guest operating system with the illusion that the guest operating system is executing as the most privileged process on a virtual machine.

Growing community of inventors

Cupertino, CA, United States of America

Todd J Kjos