Method and means for sharing I/O resources by a plurality of operating systems

• US 5,414,851 A
• Filed: 06/15/1992
• Issued: 05/09/1995
• Est. Priority Date: 06/15/1992
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Rathjen, John C. Jr., Stucki, David E., Malinowski, Paul A., Wyman, Leslie W., Oakes, Kenneth J., Brice, Frank W. Jr., Galbraith, Robert E., Meritt, Allan S., Halma, Marten J., Elliott, Joseph C., Fredericks, Kenneth J., Hough, Roger E., John, Suzanne M., Sachs, Martin W.
• Primary Examiner(s): Kriess, Kevin A.
• Application Number:
  US07/898,867
• Time in Patent Office: 1,058 Days
• Field of Search: 395/650, 395/700, 395/275
• US Class Current: 718/104
• CPC Class Codes: G06F 13/102 where the programme performs an interfacing function, e.g. device driver G06F13/105 takes precedence; scheduling within device drivers G06F9/52; contention policies within device drivers G06F9/4881
• CPC Class Codes: G06F 2009/45579 I/O management, e.g. providing access to device drivers or storage
• CPC Class Codes: G06F 9/45541 Bare-metal, i.e. hypervisor runs directly on hardware
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores

Abstract

Provides a method for increasing the connectivity of I/O resources to a multiplicity of operating systems (OSs) running in different resource partitions of a computer electronic complex (CEC) to obtain sharing of the I/O resources among the OSs of the CEC, including channels, subchannels (devices), and control units (CUs). The invention provides image identifiers (IIDs) for assigning resources to the different OSs. Each shared I/O resource has a sharing set of control blocks (CBs) in which a respective CB is assigned to (and located by) a respective IID of one of the OSs. Each of the CBs in a sharing set provides a different image of the same I/O resource. The different CB images are independently set to different states by I/O operations for the different OSs, so that the OSs can independently share the same I/O resource.

Claims

1. A method for sharing input/output (I/O) resources among a plurality of programs in a computer electronic complex, each of said plurality of programs assigned an image identifier, said method including the steps of:

storing in said computer electronic complex a sharing set of input/output control blocks, each input/output control block of said sharing set of input/output blocks including an input/output resource identifier and an image identifier;

accessing said sharing set of input/output control blocks in said computer electronic complex in response to an input/output request of one of said plurality of programs;

accessing a control block in said sharing set of input/output control blocks, accessed in the just previous step, with an image identifier of said one of said plurality of programs; and

storing states of input/output resources in said control block accessed in the just previous accessing step, whereby said control block presents separate images of the input/output resources to each of said plurality of programs.

2. A method of sharing I/O resources by a plurality of programs as defined in claim 1, wherein said computer electronic complex includes a single operating system program with multiple categories of programs in which each category has one or more image identifiers assigned to it and including the steps of associating an image identifier with each executing program in each category and utilizing an identifier of the I/O resource to select a set of input control blocks and utilizing an image identifier associated with the program to select a required input control block in the required set to enable independent use of the I/O resource by programs in the different categories using different input control blocks in the set of the input control blocks.

3. A method of sharing I/O resources by a plurality of programs as defined in claim 1, wherein said computer electronic complex includes multiple operating systems in which each operating system has one category and each category has one or more image identifiers assigned to it and including the further step of utilizing an identifier of the I/O resource to select a required set of input control blocks and utilizing an image identifier associated with the program to select a required input control block in the requested set to enable independent use of the I/O resource by programs in the different operating systems using different input control blocks in the set of input control blocks.

4. A method of sharing I/O resources by a plurality of programs as defined in claim 1, comprising the steps of:

accessing the image identifiers and control blocks by means of internal code which is not accessible to the executing programs.

5. A method of sharing I/O resources by a plurality of programs as defined in claim 1, comprising the steps of:

accessing the image identifiers by means of system software used by a computer electronic complex hypervisor, and accessing the control blocks by means of internal code, in which the image identifiers and control blocks are not accessible to any programs executing in the computer electronic complex.

6. A method of sharing I/O resources by a plurality of programs as defined in claim 1, comprising the steps of:

providing plural categories of programs in which a hypervisor is one of the categories.

7. A method of sharing I/O resources by a plurality of programs as defined in claim 1, comprising the steps of:

providing plural categories of programs in which operating systems (OSs) are one or more of the categories.

8. A method of sharing I/O resources by a plurality of programs as defined in claim 1, comprising the steps of:

communicating an I/O request directly from one of the programs to an I/O subsystem using at least one shared I/O resource without hypervisor intervention;

performing by the I/O subsystem of the I/O request using the shared I/O resource without hypervisor intervention; and

responding to the requesting program without hypervisor intervention.

9. A method of sharing I/O resources by a plurality of operating systems (OSs), comprising the steps of:

storing an image identifier (IID) in a resource identifying control block (SD) for each of plural OSs operating in a computer electronic complex (CEC);

structuring within an I/O-control storage for the CEC of a set of I/O control blocks (CBs) for each of plural I/O resources of the CEC, and associating each CB in the set with a different IID; and

accessing a required CB by an I/O processor for an I/O operation by selecting a set of CBs with an identifier of an I/O resource and by selecting a required CB in a selected set with the IID stored in the SD of an OS requesting the I/O operation, and sharing the I/O resource among the OSs associated with the IIDs of the different CBs in the set.

10. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 9, further comprising the steps of:

assigning one of the IID values with a hypervisor of the CEC (instead of with any OS) to enable the hypervisor to have its respective image of the I/O resource to permit the hypervisor to use the I/O resource independently of any OS and concurrently with the OSs.

11. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 9, further comprising the steps of:

structuring within an I/O-control storage for the CEC of a single I/O control block (CB) for any I/O resource and associating the CB with a hypervisor IID or an OS IID to provide a single image for an unshared I/O resource only to the hypervisor or OS, respectively, for enabling the hypervisor or OS, respectively, to control the unshared I/O resource in order to intermix CEC I/O operations for shared resources and for unshared resources, for which the OSs directly use shared resources without hypervisor intervention, and for which the hypervisor or the OSs can directly use unshared resources.

12. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 9, further comprising the steps of:

setting states independently in different control blocks for the concurrently executing programs of different programs to enable independent control for the different programs over the I/O resource being shared by the OSs.

13. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 12, further comprising the steps of:

communicating a representation of the IID of each I/O operation from the CEC to an I/O control unit (as the I/O resource for the I/O operation), and storing the representation of the IID by the I/O control unit to enable the I/O control unit to respond to the OS for the I/O request.

14. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 13, further comprising the steps of:

responding by the I/O control unit to the CEC for the I/O operation by the I/O control unit accessing the representation of the IID stored for the I/O operation and signalling the representation of the IID to an I/O subsystem in the CEC;

selecting by the I/O subsystem of a required set of CBs for the I/O resource, and selecting a required CB in the set for the OS requesting the I/O operation with the I/O control unit; and

queuing the required CB into an interruption queue for the OS requesting the I/O operation to enable a CPU executing the OS to handle the I/O interruption without any access to the IID to isolate the OSs from the IIDs and provide security of IIDs from the OSs.

15. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 9, further comprising the step of:

resetting the state of an image of an I/O resource for an OS (represented by a CB of the I/O resource associated with a requested IID in the CEC) without affecting the state of any other CB for the same I/O resource or the state of any CB associated with any other I/O resource by accessing and setting to an initial state only the CB of the IID and resource identified to be reset.

16. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 9, further comprising the step of:

resetting the state of CBs for all I/O resources (represented by all CBs of the I/O resources associated with a requested IID in the CEC) without affecting the state of I/O resources associated with any other IID by searching through the CBs of the CEC and setting to an initial state the CBs for all I/O resources found for the requested IID.

17. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 9, further comprising the step of:

structuring within an I/O-control storage for the CEC of a sharing set of I/O control blocks (CHCBs) for each of a plurality of physical I/O channels (each physical I/O channel being the I/O resource for a set of CHCBs) and associating each CHCB in the set with a different IID to provide a different image of the physical I/O channel to each of the OSs for enabling independent control over each physical I/O channel by the OSs sharing the physical channel.

18. A method of sharing physical I/O channels and I/O devices among a plurality of operating systems (OSs) as defined in claim 17, further comprising the steps of:

identifying in each CHCB of an offline/online field, and

setting the offline/online field independently in each of the CHCBs in the sharing set to enable each of the OSs to independently control whether an associated image of the physical channel (provided by an associated CHCB) is online or offline.

19. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 17, further comprising the step of:

specifying a channel path identifier (CHPID) as an identifier of each physical channel, and the physical channel being the I/O resource for a sharing set of CBs.

20. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 17, further comprising the step of:

structuring within an I/O-control storage for the CEC of a single I/O control block (CB) for any physical I/O channel (the channel being the I/O resource for the single CB) and associating the CB with a hypervisor IID or an OS IID to provide a single image for an unshared physical channel only to the hypervisor or the OS, respectively, for enabling only the hypervisor or the OS, respectively, to control each unshared physical channel in order to intermix shared channels and unshared channels in a CEC for enabling any of the plurality of OSs to use shared channels without hypervisor intervention, and for which the hypervisor or the OSs can directly use unshared channels.

21. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 9, further comprising the steps of:

structuring within an I/O-control storage for the CEC of a set of I/O control blocks (CBs) for each of a plurality of subchannels in which each subchannel represents an I/O device (the subchannel being the I/O resource for the set of CBs), using an identifier of the subchannel as an identifier of the set of CBs, and associating each CB in the set with a different IID to provide a different image of each subchannel to each of the OSs for enabling independent control over each I/O device by each of the OSs.

22. A method of sharing I/O resources by a plurality of operating systems (OSs) as defined in claim 9, further comprising the steps of:

structuring within an I/O-control storage for the CEC of a set of I/O control blocks (CBs) for each image of a I/O control unit (CU) connectable to the CEC (as one of the I/O resources) and associating each CB in the set with a different IID to provide a different image to the respective OSs of the CU for enabling independent control over the CU by each of the OSs.

27. A method of sharing I/O resources among a plurality of operating systems (OSs) as defined in claim 9, further comprising the steps of:

communicating by an I/O subsystem to a hypervisor of an occurrence of a special condition in the I/O subsystem, the communication including an IID and an identification of each resource affected by the special condition and an indication that a report about the special condition is to be forwarded to the OS assigned the IID; and

forwarding by the hypervisor of the report containing information about the special condition to the OS.

28. A method of sharing I/O resources among a plurality of operating-systems (OSs) as defined in claim 9, further comprising the steps of:

communicating by mean of an I/O subsystem to a hypervisor an occurrence of a special condition in the I/O subsystem, the communication including an identification of each resource affected by the special condition and an indication that a report about the special condition is to be forwarded to each OS sharing the I/O resource; and

forwarding by the hypervisor of the report containing information about the special condition to each OS sharing the I/O resource.

29. A method of sharing I/O resources among a plurality of operating systems (OSs) as defined in claim 9, further comprising the steps of:

activating a logical resource partition (LPAR) in the CEC for use by an OS with an image-reset command;

communicating to the I/O subsystem that the LPAR is to be activated; and

establishing representations of logical paths (LPs) in the I/O subsystem and affected I/O control units for the LPAR being activated.

30. A method of sharing I/O resources among a plurality of operating systems (OSs) as defined in claim 9, further comprising the steps of:

inactivating a logical resource partition (LPAR) in the CEC with an image-reset command;

communicating to the I/O subsystem the IID of the LPAR with an indication the LPAR is being inactivated; and

removing representations of logical paths (LPs) from the I/O subsystem and from affected I/O control units for the LPAR being inactivated.

23. A method of efficiently sharing I/O channels, I/O control units, and I/O devices by a plurality of operating systems (OSs), comprising the steps of:

storing in processor storage one or more special control blocks (SDs) containing OS identifiers (IIDs) for use in I/O resource sharing operations of a computer electronic complex (CEC);

storing in I/O storage a sharing set of subchannel control blocks (SSCBs) for each subchannel (for a shared I/O device), each SSCB in the set having a different IID;

storing in the I/O storage of a sharing set of channel control blocks (CHCBs) for the same I/O channel (shared channel) in which each CHCB in the set has a different IID;

storing in the I/O storage a sharing set of logical control unit control blocks (LCUCBs) for each logical I/O control unit in which each LCUCB in the set has a different IID; and

controlling an I/O operation for a requesting OS by obtaining an IID for the OS and selecting an SSCB with the IID in a sharing set for a required subchannel I/O resource, and selecting a LCUCB with the IID in a sharing set for a required control unit I/O resource, and selecting a CHCB with the IID in a sharing set for a required channel I/O resource, thereby enabling the OS to share the required I/O channel and the required I/O control unit and the required I/O device with at least one other OS operating in the CEC.

24. A method of sharing I/O channels and I/O devices among a plurality of operating systems (OSs) as defined in claim 23, further comprising the steps of:

generating by the CEC for the requesting OS of a frame header containing a specified logical path from the CEC through the required channel to a control unit associated with a device specified in the required subchannel, the logical path comprising;

a representation of the IID of the requesting OS, an address for the required channel, an address associated with a required control unit (CU);

transmitting the generated frame header to the CU using the available logical path; and

storing in a CU storage of the logical path for use by the CU in later responding to the requesting OS regarding the I/O operation.

25. A method of sharing I/O channels and I/O devices among a plurality of operating systems (OSs) as defined in claim 24, further comprising the steps of:

also storing in the CU storage of a group of addresses for logical paths associated with each of plural IIDs for the OSs in a CEC making I/O requests to the CU, and assigning a path group identifier (PGID) in the CU storage for each group of logical paths for each OS in the CEC with which the CU can communicate;

recognizing by the CU of a need to provide a response to an OS for an I/O request made to the CU by the OS, and accessing by the CU of the PGID for the OS to access the group of logical paths for the OS in the CU storage;

selecting in the CU storage of an available logical path in the accessed group of logical paths for the accessed PGID;

generating by the CU of a responding frame header containing the available logical path for the accessed PGID containing a representation of an IID of the OS to receive the response;

transmitting the responding frame header to the CEC using the available logical path; and

selecting in the receiving CEC of a sharing set of SSCBs for the subchannel of the device having an address in the responding frame, and selecting of an SSCB in the sharing set with the representation of the IID in the logical path in the responding frame header.

26. A method of sharing I/O channels and I/O devices among a plurality of operating systems (OSs) as defined in claim 25, further comprising the steps of:

identifying in each SSCB of an interruption queue to be used by the SSCB of multiple subclass interruption queues provided in the CEC; and

choosing for the queuing step of the subclass interruption queue identified in the selected SSCB.