Method and structure for data integrity in a multiple level cache system

A structure and a method provide data integrity for a multiprocessor system having a cache memory and a snoop tag cache. In one embodiment, the snoop tag cache copies the tags of a primary cache. Whenever a write operation occurs, the snoop tag cache is accessed to determine if the accessed tag matches a predetermined portion of the address of the memory location on which the write operation is performed. If so, a signal is sent to the CPU associated with the primary cache so that the corresponding entries in the primary cache and the snoop tag cache can be invalidated.