Arrangement and a method for handling interrupt requests in a data processing system in a virtual machine mode

• US 5,291,605 A
• Filed: 02/07/1992
• Issued: 03/01/1994
• Est. Priority Date: 02/08/1991
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Takagi, Hitoshi, Miyazaki, Muneharu
• Primary Examiner(s): Ray, Gopal C.
• Application Number:
  US07/831,269
• Time in Patent Office: 753 Days
• Field of Search: 395/725, 395/275, 395/325, 395/200, 395/700, 395/800, 395/425, 395/650, 340/825, 340/825.06, 371/8.1, 371/9.1, 371/11.1, 371/11.3, 371/68.3, 371/19, 370/85.1, 370/54, 370/92, 370/85.2
• US Class Current: 710/48
• CPC Class Codes: G06F 13/10 Program control for peripheral devices G06F13/14 - G06F13/42 take precedence
• CPC Class Codes: G06F 13/24 using interrupt G06F13/32 takes precedence

Abstract

A technique for handling an interrupt request issued from an I/O (Input/Output) device controller in a data processing system which is operative in a virtual machine mode in which two flags are provided, the first one of which is set to an "on" state in the case where a CPU (Central Processing Unit) is utilized as a master unit and is set to "off" state in the case where the CPU is utilized as a slave unit. The second flag is set to an "on" state in the case where the CPU is utilized as the master unit and is able to accept the interrupt request directed to a guest OS (Operating System). A first logic gate is arranged to issue a logical product of the output of the first flag and one of the outputs of the I/O device controller. A second logic gate is provided to issue a logical product of the output of the second flag and another of the outputs of the I/O device controller. Further, a third logic gate is arranged to issue a logical sum of the outputs of the first and second gates. An interrupt activator is responsive to the output of the third logic gate and then checks to see if the interrupt request issued from the I/O device controller is acceptable.

Claims

1. An arrangement for handling an interrupt request issued from an I/O (Input/Output) device controller in a data processing system which is operative in a virtual machine mode, said data processing system including a host OS (Operating System) which supervises a virtual machine monitor under control of which at least one guest OS runs, said I/O device controller being interposed between a plurality of I/O devices and a plurality of CPUs (Central Processing Units), each of said CPUs comprising:

first flag means for setting an "on" state in a case where a CPU is utilized as a master unit and for setting an "off" state in a case where said CPU is utilized as a slave unit;

second flag means for setting an "on" state in the case where said CPU is utilized as said master unit for a guest OS such that said CPU is able to accept said interrupt request directed to said guest OS;

a first logic gate for issuing a logical product of an output of said first flag means and one type of interrupt request of a plurality of interrupt requests from said I/O device controller;

a second logic gate for issuing a logical product of an output of said second flag means and another type of interrupt request of a plurality of interrupt requests from said I/O device controller;

a third logic gate for issuing a logical sum of outputs of said first and second gates; and

an interrupt activator which responds to an output of said third logic gate and which checks whether said interrupt request issued from said I/O device controller is acceptable.

2. An arrangement as claimed in claim 1, wherein said I/O device controller includes:

first means for generating a host OS interrupt request as said one type of interrupt request which is applied to said first logic gate; and

second means for generating a guest OS interrupt request as said another type of interrupt request which is applied to said second logic gate.

3. A method for handling an interrupt request issued from an I/O (Input/Output) device controller in a data processing system which is operative in a virtual machine mode, said data processing system including a host OS (Operating System) which supervises a virtual machine monitor under control of which at least one guest OS runs, said I/O device controller being interposed between a plurality of I/O devices and a plurality of CPUs (Central Processing Units), said method comprising the steps of:

(a) setting first flag means to an "on" state by a first setting input in a case where a CPU is utilized as a master unit and setting said first flag means to an "off" state by said first setting input in a case where said CPU is utilized as a slave unit;

(b) setting a second flag means to an "on" state by a second setting input in a case where said CPU is utilized as said master unit for a guest OS such that said CPU is able to accept said interrupt request directed to said guest OS;

(c) issuing a logical product of an output of said first flag means and one type of interrupt request of a plurality of interrupt requests from said I/O device controller;

(d) issuing a logical product of an output of said second flag means and another type of interrupt request of a plurality of interrupt requests from said I/O device controller;

(e) issuing a logical sum of said products which have been obtained from steps (c) and (d); and

(f) responding to said logical sum and checking to see if said interrupt request issued from said I/O device controller is acceptable.

4. A method as claimed in claim 3, further including the steps of:

(g) generating a host OS interrupt request as said one type of interrupt request from said I/O device controller in step (c); and

(h) generating a guest OS interrupt request as said another type of interrupt request from said I/O device controller in step (d).