Access control mechanism controlling access to and logical purging of access register translation lookaside buffer (ALB) in a computer system

• US 5,574,936 A
• Filed: 01/25/1995
• Issued: 11/12/1996
• Est. Priority Date: 01/02/1992
• Status: Expired due to Fees

• Current Assignee: Amdahl Corporation (Fujitsu Limited)
• Original Assignee: Amdahl Corporation (Fujitsu Limited)
• Inventors: Connell, Jefferson J., Ryba, Edward G., Weiss, David, Lipman, Peter H.
• Primary Examiner(s): Bowler, Alyssa H.
• Assistant Examiner(s): HARRITY, JOHN E
• Application Number:
  US08/378,082
• Time in Patent Office: 657 Days
• Field of Search: 395/800, 395/700, 395/775, 395/400, 395/425, 395/406, 364/228.2, 364/DIG. 1
• US Class Current: 712/30
• CPC Class Codes: G06F 12/1036 for multiple virtual address spaces, e.g. segmentation G06F12/1045 takes precedence

Abstract

An access control apparatus in a computer system for controlling access to an ALB. A host ALBID register and a guest ALBID register is provided for storing a host and a guest ALB identifier (ALBID) and a host and a guest ALBID validity indicator. Control State Software generates and stores the host and guest ALBIDs in the host and guest ALBID registers and marks valid the host and guest ALBID validity indicator whenever a host or guest mode is initiated or a logical purge is requested by a logical processor and for storing the host or guest ALBID stored in the host and guest ALBID registers when an ALB entry is made in the ALB by a logical processor. Access to an ALB entry by a logical processor is permitted when the logical processor is in the host mode if the ALBID in the ALB entry matches the host ALBID stored and the valid indicator is marked valid in the host ALBID register and when the logical processor is in the guest mode if the ALBID in the ALB entry matches the guest ALBID stored and the valid indicator is marked valid in the guest ALBID register. A host logical purge is accomplished by marking invalid the host and guest validity indicators in the host and guest ALBID registers. A guest Logical purge is accomplished by marking invalid the guest validity indicator in the guest ALBID register.

Claims

1. An access control apparatus in a computer system, said computer system including storage, physical processors, logical processors (LP'"'"'s) which can operate in either a host or guest mode, access registers, an access-register translator (ART), an ART-lookaside buffer (ALB) for storing entries created by said logical processors, said access control apparatus comprising:

a host ALBID register for storing an ALB identifier (ALBID) and an ALBID validity indicator for the host mode of the logical processor;

a guest ALBID register for storing an ALB identifier (ALBID) and an ALBID validity indicator for the most recent guest mode on the logical processor;

first means for generating and storing in said host ALBID register an ALB identifier (ALBID) and for marking valid said ALBID validity indicator in said host ALBID register when a host mode is initiated on said logical processor and when a logical purge is requested during the host mode by said logical processor;

second means for generating and storing in said guest ALBID register an ALB identifier (ALBID) and for marking valid said ALBID validity indicator in said guest ALBID register when a guest mode is first initiated on said logical processor and when a logical purge is requested during a guest mode by said logical processor;

third means for storing in each ALB entry the host ALBID in said host ALBID register when an ALB entry is made in said ALB by said logical processor when said logical processor is in said host mode;

fourth means for storing in each ALB entry the guest ALBID in said guest ALBID register when an ALB entry is made in said ALB by said logical processor when said logical processor is in said guest mode;

fifth means for permitting access by the logical processor while in the host mode to an ALB entry in said ALB when said ALBID in said ALB entry matches the ALBID stored in said host ALBID register and the valid indicator in said ALBID host register is marked valid; and

sixth means for permitting access by the logical processor while in the guest mode to an ALB entry in said ALB when said ALBID in said ALB entry matches the ALBID stored in said guest ALBID register and the valid indicator in said ALBID guest register is mark valid.

2. The access control apparatus of claim 1 wherein each said ALBID generated by said first and second means that uniquely associates a domain number, a logical storage address, and a State Descriptor Address when a logical processor is running in the guest mode.

3. The access control apparatus of claim 1 wherein said fifth means includes:

seventh means for checking the validity indicator in the host ALBID register when access to said ALB is requested by a logical processor in said host mode and for initiating a Control Intercept to Control State Software (CSSW) when the validity indicator is marked invalid; and

wherein said sixth means includes;

eighth means for checking the validity indicator in the guest ALBID register when access to said ALB is requested by a logical processor in said guest mode and for initiating a Control Intercept to Control State Software (CSSW) when the validity indicator is marked invalid.

4. The access control apparatus of claim 3 wherein:

said first means resides in said CSSW stored in said storage and in response to said Control Interrupt and said logical processor being in said host mode generates and stores said host ALBID in said host ALBID register, marks valid said validity indicator in said host ALBID register and then returns control back to the logical processor for retrying the request for access to the ALB; and

said second means resides in said CSSW stored in said storage and in response to said Control Interrupt and said logical processor being in said guest mode generates and stores said guest ALBID in said guest ALBID register, marks valid said validity indicator in said guest ALBID register and then returns control back to the logical processor for retrying the request for access to the ALB.

5. The access control apparatus of claim 3 wherein:

said first means in response to a request for a logical purge marks as invalid said validity indicator in said host ALBID register and said guest ALBID register which effects a logical purge by causing a new ALBID to be generated for the host mode of the logical processor.

6. The access control apparatus of claim 3 wherein:

said second means in response to a request for a logical purge while the logical processor is in said guest mode marks as invalid said validity indicator in said guest ALBID register which effects a logical purge by causing a new ALBID to be generated for said guest mode of the logical processor.

7. The access control apparatus of claim 3 wherein:

said third and fourth means reside in said CSSW stored in said storage.

8. An access control apparatus in a computer system, said computer system including storage, physical processors, logical processors (LP'"'"'s) which can operate in either a host or guest mode, access registers, an access-register translator (ART), an ART-lookaside buffer (ALB) for storing entries created by said logical processors, said access control apparatus comprising:

a host ALBID register for storing an ALB identifier (ALBID) and an ALBID validity indicator for the host mode of the logical processor;

a guest ALBID register for storing an ALB identifier (ALBID) and an ALBID validity indicator for the most recent guest mode on the logical processor;

Control State Software (CSSW) stored in said storage performing the functions of;

generating and storing in said host ALBID register an unique ALB identifier (ALBID) and for marking valid said ALBID validity indicator in said host ALBID register when a host mode is initiated on said logical processor and when a logical purge is requested during the host mode by said logical processor;

generating and storing in said guest ALBID register an unique ALB identifier (ALBID) and for marking valid said ALBID validity indicator in said guest ALBID register when a guest mode is first initiated on said logical processor and when a logical purge is requested during a guest mode by said logical processor;

storing in each ALB entry the host ALBID in said host ALBID register when an ALB entry is made in said ALB by said logical processor when said logical processor is in said host mode; and

storing in each ALB entry the guest ALBID in said guest ALBID register when an ALB entry is made in said ALB by said logical processor when said logical processor is in said guest mode;

first means for permitting access by the logical processor while in said host mode to an ALB entry in said ALB when said ALBID in said ALB entry matches the ALBID stored in said host ALBID register and the valid indicator in said ALBID host register is marked valid; and

second means for permitting access by the logical processor while in the guest mode to an ALB entry in said ALB when said ALBID in said ALB entry matches the ALBID stored in said guest ALBID register and the valid indicator in said ALBID guest register is marked valid.

9. The access control apparatus of claim 8 wherein each said ALBID generated by said CSSW uniquely associates a domain number, a logical storage address, and a State Descriptor Address when a logical processor is running in the guest mode.

10. The access control apparatus of claim 8 wherein said first means includes:

third means for checking the validity indicator in the host ALBID register when access to said ALB is requested by a logical processor in said host mode and for initiating a Control Intercept to said Control State Software (CSSW) when the validity indicator is marked invalid; and

wherein said second means includes;

fourth means for checking the validity indicator in the guest ALBID register when access to said ALB is requested by a logical processor in said guest mode and for initiating a Control Intercept to said Control State Software (CSSW) when the validity indicator is marked invalid.

11. The access control apparatus of claim 10 wherein:

said CSSW in response to said Control Interrupt and said logical processor being in said host mode performs the functions of generating and storing said host ALBID in said host ALBID register, marking valid said validity indicator in said host ALBID register and then returning control back to said logical processor for retrying the request for access to the ALB; and

said CSSW in response to said Control Interrupt and said logical processor being in said guest mode performs the functions of generating and storing said guest ALBID in said guest ALBID register, marking valid said validity indicator in said guest ALBID register and then returning control back to the logical processor for retrying the request for access to the ALB.

12. The access control apparatus of claim 8 wherein said CSSW performs a logical purge in response to a logical purge request during a host mode of operation of a logical processor by performing the function of:

marking invalid said validity indicator in said host ALBID register;

generating a new host ALBID;

storing said new host ALBID in said host ALBID register; and

marking valid said validity indicator in said host ALBID register.

13. The access control apparatus of claim 8 wherein said CSSW performs a logical purge in response to a logical purge request during a host mode of operation of a logical processor by performing the function of:

marking invalid said validity indicator in said guest ALBID register;

generating a new guest ALBID;

storing said new guest ALBID in said host ALBID register; and

marking valid said validity indicator in said guest ALBID register.