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Unified Translation Lookaside Buffer for Host/Guest Translation Results in a Nested Translation Environment

IP.com Disclosure Number: IPCOM000249321D
Publication Date: 2017-Feb-16
Document File: 1 page(s) / 61K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a unified translation lookaside buffer (TLB) for host/guest translation results in a nested translation environment.

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Unified Translation Lookaside Buffer for Host/Guest Translation Results in a Nested Translation Environment

Virtual memory management in a nested translation environment requires multiple levels of address translation with each level needing a translation lookaside buffer (TLB) to improve translation performance. This increases the area and power required for the memory management unit and can result in unused TLB entries if the workload is not balanced between Host and Guest translations.

The novel contribution is a single unified TLB is developed for use by all virtual-to-real memory translation results.

On subsequent translation requests, the method is to search the TLB and only indicate a hit if address tag as well as the translation tag level match the translation request type. The number of entries allocated for each level translation level is dynamically managed as the requests are received.

This solution saves area and power by allowing a smaller number of total entries versus separate TLBs for each translation level. Each TLB entry has an additional tag bit to indicate from which level of the translation process the TLB entry was created (i.e., Guest/Host). Each TLB lookup includes the requester type (i.e., Guest/Host) and only indicates a hit if the additional tag hit as well as the address tag match. All entries with the single TLB can be allocated to any request type; no hard division exists allocating a certain number of entries to a particular request type.