Ensuring forward progress for nested translations in a memory management unit

A method for ensuring forward progress for nested translations in a memory management unit (MMU) comprising:

• receiving a plurality of nested translation requests, wherein each of the plurality of nested translation requests requires at least one congruence class lock indicating an exclusive use of a congruence class comprising a portion of a lookaside buffer, and wherein translation of each of the plurality of translation requests requires a primary translation table and a second translation table;
• detecting, using a congruence class scoreboard tracking congruence class locks and congruence class reservations, a collision of the plurality of nested translation requests, wherein the collision comprises a state in which one or more of the nested translation requests cannot proceed due to the required congruence class locks;
• quiescing, in response to detecting the collision of the plurality of nested translation requests, a translation pipeline in the MMU including switching operation of the translation pipeline from a multi-thread mode to a single-thread mode and marking a first subset of the plurality of nested translation requests as high-priority nested translation requests;
• and
• servicing the high-priority nested translation requests through the translation pipeline in the single-thread mode.