Hewlett-Packard Development Company, L.p.

Digital Equipment Corporation

Compaq Information Technologies Group, L.p.

Judith Shelhorse Hall

Andrew Halstead Mason

Mary Ellen Zurko

Morrie Gasser

Clifford Earl Kahn

Steven B Lipner

Paul Douglas Sawyer

Thomas Andrew Casey, Jr

Leslie Richard Kendall

Paul T Robinson

Richard T Witek

A method for executing trusted commands, in which a trusted command is first received from a user at a user terminal and parsed by untrusted code; then passed to a trusted computing base for execution. The trusted computing base displays some indication of what is to be done back to the user for confirmation. Confirmation of the commands prevents unauthorized modification of the commands and increases system confidence. A randomly (or pseudo-randomly) generated process identifier is employed to verify the existence of a trusted path.

Verification of trusted-path commands

Processing trusted commands in trusted and untrusted environments

A method for executing trusted commands, in which a trusted command is first received from a user at a user terminal and parsed by untrusted code; then passed to a trusted computing base for execution. The trusted computing base displays to the user for confirmation indication of what is to be done. Confirmation of the commands prevents unauthorized modification of the commands and increases system confidence. A randomly (or pseudo-randomly) generated process identifier is employed to verify the existence of a trusted path.

Method for executing trusted-path commands

In a system for implementing virtual machines a Virtual Machine Monitor (VMM) is assigned an address space separate and distinct from the address space assigned to the virtual machines (VMs). A VM-bit is used to determine whether the processor is executing a process in the VM or the VMM. Through the use of the separate address spaces and the VM-bit a system is disclosed wherein the VMM can take full advantage of all the protection rings offered by the system on which it runs and the VMs are also allowed to operate in an environment that essentially offers the same number of real protection rings as are available on the underlying computer system.

Protection ring extension for computers having distinct virtual machine

A central processing unit (CPU) executing a virtual memory management system employs a translation buffer for caching recently used page table entries. When more than one process is executing on the CPU, the translation buffer is usually flushed when a context switch is made, even though some of the entries would still be valid for commonly-referenced memory areas. An address space number feature is employed to allow entries to remain in the translation buffer for processes not currently executing, and the separate processes or the operating system can reuse entries in the translation buffer for such pages of memory that are commonly referenced. To allow this, an 'address space match' entry in the page table entry signals that the translation buffer content can be used when the address tag matches, even though the address space numbers do not necessarily match. When executing virtual machines on this CPU, with a virtual machine monitor, the address space match feature is employed among processes of a virtual machine, but an additional entry is provided to disable the address space match feature for all address space numbers for the virtual machine monitor.

Translation buffer for virtual machines with address space match

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Sudbury, MA, United States of America

Judith Shelhorse Hall