Apparatus and method for handling maintenance operations for an address translation cache

Each entry of a set associative address translation cache (ATC) stores address translation data (ATD) used by processing circuitry when converting a virtual address into a corresponding physical address. The processing circuitry operates in multiple contexts, and each entry has an associated context identifier identifying the context to which the ATD therein applies. A masking structure comprises at least one mask storage and, for each mask storage, an associated context storage. Each mask storage provides a mask field for each set of the ATC. Control circuitry responds to a maintenance request, specifying a given context and requiring a maintenance operation to be performed in respect of each entry of the ATC that stores ATD applying to the given context, by setting each mask field in a selected mask storage, storing an indication of the given context in the associated context storage, and issuing a response to a request source.