Ats pri support with implicit cache

Abstract

The present disclosure generally relates to improved address translation. Rather than fetching translated addresses using ATS/ATC, a HIM address translation search engine (HATS) is used through implementing the ATC in a layer above per an NVMe command. The HATS is an engine that will monitor pointers with untranslated addresses and will fetch the translated addresses for the pointers. Once the translated addresses are fetched for the pointer, the HATS will overwrite the untranslated address with the translated address. The HATS will then update the status of the pointers. When a translation request fails, the device will use PRI to request the translated address. During a translation request fail the device will drain any incoming requests while skipping the data transfer phase. The device will not block any other requests in a queue. Once that translated address is received through the PRI flow, the status of the pointer will be updated. After PRI completes, the device will return to using the HATS to get all the translated addresses for the pointers with an untranslated address status. After getting the translated addresses, the device shall use the translated addresses to perform DMA operations.