Electrical computers and digital processing systems: multicomput – Computer-to-computer data routing – Least weight routing
Reexamination Certificate
1998-03-24
2004-01-20
Follansbee, John (Department: 2126)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data routing
Least weight routing
C711S203000
Reexamination Certificate
active
06681238
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of computer system design and in particular to a method and system for providing an internal machine hardware function, typically implemented in the main storage of a physical hardware-based computing system, in a virtual machine of a computing system. The invention provides an operational interface between a first computer system environment and a separate and secure storage environment, which is not available for the execution of customer programs. By implementing the operational interface, execution of a microcode-based hardware machine function, initially situated in the secured storage environment is provided to the user through one or more isolated virtual machines of the first computer system environment, so as to provide its functionality to programs running in other portions of the first computer system environment.
BACKGROUND OF THE INVENTION
Many modern computer systems implement various types of clustered architectures. In particular, the Parallel Sysplex clustered system offered by International Business Machines Corporation (IBM) (Parallel Sysplex and IBM are registered trademarks of International Business Machines Corporation, the present assignee hereof) comprise one or more S/390 servers coupled via intersystem links to one or more Coupling Facilities (CFs) which provide a structured, shared electronic storage for the coupled servers (S/390 is a registered trademark of IBM).
Establishment of a Parallel Sysplex computing system can be a work-intensive task which involves the acquisition and customization of new hardware and software. It has therefore been found advantageous to offer customers the opportunity to determine the benefits derived from the Parallel Sysplex system implementation by providing an emulated Parallel Sysplex computing environment for customer testing.
The foregoing problem has been previously addressed by providing a facility whereby the function of the Parallel Sysplex system can be emulated within a single hardware machine. In U.S. Pat. No. 5,564,040 to Kubala (assigned to the present assignee and incorporated herein by reference), the program code for performing the functions of the Coupling Facility is loaded into a maximum of two logical partitions of main storage in the hardware machine. In the Kubala patent, the (server mode) CF memory partitions are non-user accessible and provide Coupling Facility functions by interacting with user-accessible (non-server mode) memory partitions to simulate the function of a Parallel Sysplex system. While the Kubala patent does provide a simulated Parallel Sysplex system, it is limited to implementations including only two simulated Coupling Facilities and requires the allocation of a logical partition of main storage for each of these Coupling Facility instances.
In accordance with the foregoing it is clear that a solution which provides a customer with the ability to simulate highly complex Parallel Sysplex implementations including up to eight Coupling Facilities in a single Parallel Sysplex system, or alternatively to test multiple Parallel Sysplex systems on a single hardware machine without requiring the actual hardware systems or storage necessary for the real hardware-based implementation would prove advantageous to such customers. Moreover, it would be further beneficial to provide this simulated hardware function within a software environment having pre-existing debugging facilities with which the customer could more-effectively test the virtualized hardware implementation.
In response to these identified user requirements, via the facilities of the present invention, the services of the Coupling Facility or any other microcode-based hardware machine function can now be provided in a virtual machine of VM/ESA (VM), which is referred to as a virtual machine hypervisor or supervisor of other operating systems (VM/ESA is a registered trademark of IBM). Consequently, customers may test and debug the programs that are to use Coupling Facility services in a simulated Parallel Sysplex system comprising virtual machines rather than real machines.
This virtualization, by utilizing pageable storage, also allows unlimited multiple copies of the function to exist within a single computing system, each in its own virtual machine. Accordingly, the VM operating system allows a user to emulate one or more complete, independent simulated Parallel Sysplex systems, each with one or more CFs, in a single machine or logical partition thereof. This enables customer testing of large complex multisystem configurations without requiring those customers to acquire the actual hardware required for the configurations, or to possess the larger real storage required for such testing.
An additional advantage of implementing the simulated hardware machine function within the VM operating system is the availability within VM of existing debugging facilities and the ease of virtual machine re-configuration therein of this virtual Parallel Sysplex implementation. Users of the VM operating system have long utilized these facilities to test other software-based features, and accordingly this familiarity serves to aid in the testing of the virtual Parallel Sysplex system.
SUMMARY OF THE INVENTION
Advantageous features offered via the present invention address the foregoing problems and shortcomings of the prior art, and in particular, include implementation of an operational interface for virtualizing an internal hardware-based machine capability of a computing system. The interface is implemented between the VM/ESA (VM) operating-system hypervisor, executing on the main processors of a machine, or Central Electronics Complex (CEC), and the Service Element (SE) of the CEC, a separate hardware and program-execution domain within the CEC that is not accessible to users of the system and is not available for the execution of user programs. This interface provides a facility whereby a programmed hardware-based machine function called the Coupling Facility (CF), which typically executes in the main storage of a single hardware machine or logical partition thereof, is established for execution in one or more isolated virtual machines of VM, where it can be used to provide service to programs in other virtual machines in the same hardware machine or logical partition through a VM simulation of a coupling-hardware interface.
In general, a hardware machine function may be implemented at the normal architected programming-interface level of the hardware machine, yet be an integral part of the machine definition and not distributed as a programming product. An example of such an implementation is the CF function, the virtualization of which forms the basis for the subsequent detailed description section of this patent. The program code providing this function resides in the Service Element (SE) of the hardware system.
The Coupling Facility is implemented in proprietary microcode termed Coupling Facility Control Code (CFCC), which is classified by IBM as Licensed Internal Code (LIC) and not intended for access by customers using the computer system. Accordingly, a further feature of the present invention creates a new class of “encapsulated” virtual machines in VM to protect the proprietary nature of the implementation of the LIC function from unauthorized access in a virtual machine. This protection is additionally important since a violation of the integrity of the LIC function can have a negative effect on the operation of the multiple computing systems comprising a virtual Parallel Sysplex system, potentially creating difficult debugging situations.
In contrast to typical unrestricted virtual machines in VM which are available for logon and full use by a user, an encapsulated virtual machine permits no such logon and regular use. Moreover, the system commands which are normally available to virtual-machine users are restricted in an encapsulated virtual machine. Requests for the services of an encapsulated virtual machine, which may be issued by users or pro
Brice, Jr. Frank W.
Hefferon Eugene P.
Scalzi Casper A.
Tarcza Richard P.
Bullock, Jr. Lewis A.
Ehrlich Marc A.
Follansbee John
Gonzalez Floyd A.
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