1. A method of data processing in a data processing system including a processor core having a store-through upper level cache and a store-in lower level cache, the method comprising: in response to a first instruction in the processor core, generating a copy-type request and transmitting the copy-type request to the lower level cache, wherein the copy-type request specifies a source real address; in response to a different second instruction in the processor core, generating a paste-type request and transmitting the paste-type request to the lower level cache, wherein the paste-type request specifies a destination real address; only in response to receipt by the lower level cache of both the copy-type request and the paste-type request from the processor core, the lower level cache copying a data granule from a storage location specified by the source real address into a non-architected buffer; and in response to receipt of the paste-type request from the processor core at the lower level cache, the lower level cache writing the data granule from the non-architected buffer to a storage location specified by the destination real address.