Method and apparatus for controlling reconfiguration of storage-device memory areas

• US 5,684,974 A
• Filed: 03/13/1995
• Issued: 11/04/1997
• Est. Priority Date: 03/17/1994
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Onodera, Osamu
• Primary Examiner(s): Moore, David K.
• Assistant Examiner(s): NGUYEN, THAN VINH
• Application Number:
  US08/402,371
• Time in Patent Office: 967 Days
• Field of Search: 340/172.5, 395/405, 395/412, 395/406, 395/416, 395/419, 395/415, 395/421.1, 395/417, 395/477.01
• US Class Current: 711/202
• CPC Class Codes: G06F 12/0284 Multiple user address space allocation, e.g. using different base addresses interprocessor communication G06F15/163
• CPC Class Codes: G06F 12/121 using replacement algorithms
• CPC Class Codes: G06F 2212/151 Emulated environment, e.g. virtual machine

Abstract

An apparatus and method for controlling the reconfiguration of the physical storage area in a real storage device employed by an information processing system.

The invention includes an address reconfiguration array having a plurality of storage blocks which are each assigned to a virtual computer. Each storage block is composed of a plurality of host real-address entries. Assigned to a storage area in the logical memory of a virtual computer, each host real-address entry includes a validity field containing a validity bit and a host real-address field containing a high-order part of the start address of a real storage segment allocated to the storage area. The invention also includes a selector which receives the identifier of a virtual computer and a logical address from the virtual computer, and makes use of the identifier for choosing a storage block from the address reconfiguration array and a high-order portion of the logical address for selecting a host real-address entry from the chosen storage block. The value of the host real-address field of the selected host real-address entry, the high-order part of a real address, is then read out from the selected host real-address entry, and is merged with the low-order portion of the logical address in order to create a real address. If the validity bit indicates that the contents of the host real-address entry are invalid, however, the virtual computer is interrupted. A change to the contents of the address reconfiguration array can be made by replacing the contents of a host real-address entry chosen by the selector with update data.

Claims

1. A method of controlling reconfiguration of a physical storage area of a real storage device included in an information processing apparatus having said real storage device, and a plurality of virtual computers operating on a central processing unit, wherein said physical storage area is logically divided into a plurality of storage segments to be allocated to a plurality of logical memories each employed in one of said virtual computers operating on said central processing unit, and an address reconfiguration array which includes a plurality of storage blocks each being assigned to one of said virtual computers and having its logical memory divided into a plurality of logical storage areas according to a high-order portion of logical addresses thereof, wherein each of said storage blocks is composed of a plurality of host real-address entries each being assigned to one of said logical storage areas and used for storing a high-order part of a start address of one of said storage segments of said physical storage area, said method comprising the steps of:

selecting a storage block from said address reconfiguration array in accordance with an identifier of a virtual computer, said identifier being issued by said virtual computer;

selecting one of said host real-address entries from the selected storage block in accordance with said high-order portion of a logical address specified by said virtual computer which issued said identifier; and

generating a real address of said real storage device by reading out said high-order part of a start address of one of said storage segments from the selected host real-address entry, and merging said high-order part of said start address of one of said storage segments with a remaining low-order portion of said logical address to create said real address of said storage segment of said real storage device.

2. A method according to claim 1, wherein each host real-address entry comprises a validity field for storing a flag indicating whether or not contents of said host real-address entry are valid, and a host real-address field for storing said high-order part of a start address of one of said storage segments of said real storage device;

and

wherein said generating step comprises the steps of;

examining said flag in said validity field to determine whether or not said contents of said selected host real-address entry are valid,

reporting, when said contents of the selected host real-address entry are found invalid, a cause of a program interrupt indicating an addressing exception to said virtual computer making said request, and

carrying out, when said contents of the selected host real-address entry are found valid, said request for address conversion and using an address resulting from address conversion as a valid real address of said real storage device.

3. A method according to claim 2 wherein said generating step further comprises the steps of:

updating, when only validity information is issued to said address reconfiguration array in said request for address conversion to make a change to contents of one of said host real-address entries selected by said request for address conversion, only said validity field of the selected host real-address entry; and

updating, when only said high-order part of a start address of one of said storage segments is issued to said address reconfiguration array in said request for address conversion to make a change to contents of one of said host real-address entries selected by said request for address conversion, only said host real-address field of the selected host real-address entry.

7. A method according to claim 1, further comprising the step of:

making a change to contents of the selected host real-address entry by replacing previous contents of the selected host real-address entry.

8. A method according to claim 2, further comprising the step of:

making a change to contents of the selected host real-address entry by replacing previous contents of the validity and host real-address fields of the selected host real-address entry.

4. An apparatus for controlling reconfiguration of a physical storage area of a real storage device included in an information processing system having said real storage device and a plurality of virtual computers operating on a central processing unit, wherein said physical storage area is logically divided into a plurality of storage segments to be allocated to a plurality of logical memories each employed in one of said virtual computers operating on said central processing unit, said apparatus comprising:

an address reconfiguration array which includes a plurality of storage blocks each being assigned to one of said virtual computers and having its logical memory divided into a plurality of logical storage areas according to a high-order portion of logical addresses thereof, wherein each of said storage blocks is composed of a plurality of host real-address entries each being assigned to one of said logical storage areas and used for storing a high-order part of a start address of one of said storage segments of said physical storage area;

a selector for selecting a storage block from said address reconfiguration array in accordance with an identifier of a virtual computer, said identifier being issued by said virtual computer and selecting one of said host real-address entries from the selected storage block in accordance with a high-order portion of a logical address specified by said virtual computer which issued said identifier; and

an address generator for generating a real address of said real storage device by reading out said high-order part of a start address of one of said storage segments from the selected host real-address entry and merging said high-order part of a start address of one of said storage segments with a remaining low-order portion of said logical address to create said real address of said storage segment of said real storage device.

5. An apparatus according to claim 4, further comprising:

modification means for making a change to contents of the selected host real-address entry by replacing previous contents of the selected host real-address entry.

6. An apparatus according to claim 4, wherein each of said host real-address entries comprises:

a validity field for storing a flag indicating whether or not contents of said host real-address entry are valid; and

a host real-address field for storing said high-order part of a start address of one of said storage segments.