Browse Prior Art Database

Mechanism for Dynamic Registering and Notifying Hypervisor Clients of Updates to High-UseTranslation Control Entries

IP.com Disclosure Number: IPCOM000030311D
Original Publication Date: 2004-Aug-05
Included in the Prior Art Database: 2004-Aug-05
Document File: 4 page(s) / 57K

Publishing Venue

IBM

Abstract

This invention describes a method by which performance may be increased in a logical partitioned environment which uses address translation tokens as a protection mechanism between multiple partitions performing virtual I/O between them. The token to address translation can be cached by the client, which is notified by the address translation management code when the token to address translation is modified.

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Mechanism for Dynamic Registering and Notifying Hypervisor Clients of Updates to High-UseTranslation Control Entries

Translation control entries are used to map physical memory pages to an address token in order to offer address protection in a logically partitioned environment. These address tokens can then be passed between partitions. When an operation is to be done that requires access to the memory mapped to the address token, a partition passes the address token to the hypervisor which can perform access checks prior to allowing the operation to continue.

     Current Virtual I/O architecture (Inter-Partition communication) requires a partition to allocate space for a queue structure, map this queue structure with a translation control entry, and register the queue by giving the hypervisor the address token. Whenever the partition wishes to perform an operation on this queue structure, the I/O token is passed to the hypervisor. The hypervisor must then invoke translation control entry management functions to validate and translate the address token to the physical memory address that it was mapped to. Operations on this queue structure are very frequent, thus the hypervisor spends alot of unnecessary cycles by repeatedly retranslating the same static address token.

     This invention solves the problem of having to repeatedly translate the same high-use, static address token in order to access structures that are mapped via a translation control entry.

This invention is comprised of:
1.) A mechanism by which hypervisor clients can register high-use address tokens.
2.) A mechanism by which changes to translation control entries referred to by high-use address tokens is recognized
3.) A mechanism by which clients are notified when changes to translation control entries referred to by high-use address tokens occur.

     This invention is useful when the following operating system elements are present:
A.) A trusted code layer (referred to as a "hypervisor" in this document) which performs address protection policing.
B.) A set of translation control entry management functions. Among other things, these functions map translation control entries to physical memory pages, and returns to the partition an address token used to refer to the translation control entry.
C.) A trusted code component of the hypervisor which does operations on physical memory mapped by address tokens.

     The invention has two flows as shown in Figures 1 and 2. The first flow below describes the registering and use of the high use token. The second flow describes the recognition of a change to a high use token, and the notification of the change to the registered code entr...