Abstract: An apparatus has memory management circuitry to control access to a memory system based on access control information defined in table entries of a table structure comprising at least two levels of access control table. Table accessing circuitry accesses the table structure to obtain the access control information corresponding to a target address. For a given access control table at a given level of the table structure other than a starting level, the table accessing circuitry selects a selected table entry of the given access control table corresponding to the target address, based on an offset portion of the target address. A size of the offset portion is selected based on a variable nesting control parameter specified in a table entry of a higher-level access control table at a higher level of the table structure than the given access control table.

Abstract: A type of translation lookaside buffer (TLB) invalidation instruction is described which specifically targets a first type of TLB which stores combined stage-1-and-2 entries which depend on both stage 1 translation data and the stage 2 translation data, and which is configured to ignore a TLB invalidation command which invalidates based on a first set of one or more invalidation conditions including an address-based invalidation condition depending on matching of intermediate address. A second type of TLB other than the first type ignores the invalidation command triggered by the first type of TLB invalidation instruction. This approach helps to limit the performance impact of stage 2 invalidations in systems supporting a combined stage-1-and-2 TLB which cannot invalidate by intermediate address.

Abstract: A context-information-dependent instruction causes a context-information-dependent operation to be performed based on specified context information indicative of a specified execution context. A context information translation cache 10 stores context information translation entries each specifying untranslated context information and translated context information. Lookup circuitry 14 performs a lookup of the context information translation cache based on the specified context information, to identify whether the context information translation cache includes a matching context information translation entry which is valid and which specifies untranslated context information corresponding to the specified context information. When the matching context information translation entry is identified, the context-information-dependent operation is performed based on the translated context information specified by the matching context information translation entry.

Abstract: Address translation circuitry (20) converts virtual addresses into physical addresses with reference to intermediate level and final level page tables. Final level descriptors within final level page tables identify address translation data for an associated region of memory. Intermediate level descriptors within intermediate level page tables identify intermediate address translation data used to identify an associated page table at a next level of the page tables. Page table update circuitry (35) maintains state information within each final and intermediate level descriptor, and updates the state information from a clean state to a dirty state: in the final level descriptors to indicate that a modification of content of the associated memory region is permitted; in the intermediate level descriptors to indicate occurrence of an update from the clean state to the dirty state within the state information of any final level descriptors that are accessed via that intermediate level descriptor.

Abstract: An apparatus comprises a cache comprising a plurality of cache entries, and cache replacement control circuitry to select, in response to a cache request specifying a target address missing in the cache, a victim cache entry to be replaced with a new cache entry. The cache request specifies a partition identifier indicative of an execution environment associated with the cache request. The victim cache entry is selected based on re-reference interval prediction (RRIP) values for a candidate set of cache entries. The RRIP value for a given cache entry is indicative of a relative priority with which the given cache entry is to be selected as the victim cache entry. Configurable replacement policy configuration data is selected based on the partition identifier, and the RRIP value of the new cache entry is set to an initial value selected based on the selected configurable replacement policy configuration data. [FIG.

Abstract: An apparatus has an address translation cache (12, 16) having a number of cache entries (40) for storing address translation data which depends on one or more page table entries of page tables. Control circuitry (50) is responsive to an invalidation request specifying address information to perform an invalidation lookup operation to identify at least one target cache entry to be invalidated. The target cache entry is an entry for which the corresponding address translation data depends on at least one target page table entry corresponding to the address information. The control circuitry (50) selects one of a number of invalidation lookup modes to use for the invalidation lookup operation in dependence on page size information indicating the page size of the target page table entry. The different invalidation lookup modes correspond to different ways of identifying the target cache entry based on the address information.

Abstract: Apparatus comprises address processing circuitry to detect information relating to an input memory address provided by address information tables; the address processing circuitry being configured to select an address information table at a given table level according to earlier information entry in an address information ;and the address table; and the address processing circuitry being configured to select an information entry in the selected address information table according to an offset component, the offset component being defined so that contiguous instances of that portion of the input memory address indicate contiguously addressed information entries; the address processing circuitry comprising detector circuitry to detect whether indicator data is set to indicate whether a group of one or more contiguously addressed information entries in the selected address information table provide at least one base address indicating a location within a contiguously addressed region comprising multiple address

Abstract: Memory management apparatus comprises input circuitry to receive a translation request defining a first memory address within a first memory address space; prediction circuitry to generate a predicted second memory address within a second memory address space as a predicted translation of the first memory address, the predicted second memory address being a predetermined function of the first memory address; control circuitry to initiate processing of the predicted second memory address; translation and permission circuitry to perform an operation to generate a translated second memory address for the first memory address associated with permission information to indicate whether memory access is permitted to the translated second memory address; and output circuitry to provide the translated second memory address as a response to the translation request when the permission information indicates that access is permitted to the translated second memory address.

Abstract: A memory system component comprises transaction handling circuitry to receive memory access transactions. Each memory access transaction specifies at least: an issuing domain identifier which indicates an issuing security domain specified by an issuing master device for the memory access transaction, where the issuing security domain is one of a plurality of security domains; a target address; and a security check indication which indicates whether it is already known that the memory access transaction would pass a security checking procedure. The security checking procedure determines whether the memory access transaction indicating said issuing security domain is authorised to access the target address, based on control data indicative of which of the plurality of security domains are allowed to access the target address. The memory system component comprises control circuitry to determine, on the basis of the security check indication, whether the security checking procedure still needs to be performed.

Abstract: An apparatus has memory management circuitry to control access to a memory system based on access control information defined in table entries of a table structure comprising at least two levels of access control table. Table accessing circuitry accesses the table structure to obtain the access control information corresponding to a target address. For a given access control table at a given level of the table structure other than a starting level, the table accessing circuitry selects a selected table entry of the given access control table corresponding to the target address, based on an offset portion of the target address. A size of the offset portion is selected based on a variable nesting control parameter specified in a table entry of a higher-level access control table at a higher level of the table structure than the given access control table.

Abstract: Address translation circuitry (16) translates a virtual address specified by a memory access request issued by requester circuitry into a target physical address (PA). Requester-side filtering circuitry (20) performs a granule protection lookup based on the target PA and a selected physical address space (PAS) associated with the memory access request, to determine whether to allow the memory access request to be passed to a cache or interconnect. In the granule protection lookup, the requester-side filtering circuitry obtains granule protection information corresponding to a target granule of physical addresses including the target PA, which indicates at least one allowed PAS associated with the target granule, and blocks the memory access request when the granule protection information indicates that the selected PAS is not an allowed PAS.

Abstract: Apparatuses, methods and techniques for controlling memory access in a data processing system are disclosed. The operating data processing system comprises multiple subsystems, each comprising at least one processing element and at least one peripheral device. Memory transaction control circuitry receives memory transaction information of a memory transaction comprising a stream identifier indicative of the issuing peripheral device. A main control register indicates an address of a stream table having multiple entries each comprising an owning subsystem identifier. At least one subsystem control register corresponding to each subsystem of the multiple subsystems stores memory access checking configuration information. On receipt of the memory transaction information an entry of the stream table is selected in dependence on the stream identifier. At least one subsystem control register. corresponding to the subsystem identified by the owning subsystem identifier of the entry is selected.

Abstract: An apparatus is described that has processing circuitry for performing operations, and a communication path employed by the processing circuitry to access a first memory. Switch circuitry, when activated, is connected to the communication path. The processing circuitry issues access commands specifying addresses to be accessed, where each address is mapped to location in a memory system in accordance with a system address map. The memory system comprises at least the first memory and a second memory. When in a particular mode, the processing circuitry performs operations that require access to only a subset of the locations provided in the first memory. The switch circuitry is arranged, whilst the processing circuitry is in the particular mode, to be activated in order to intercept the access commands issued over the communication path that specify addresses mapped by the system address map to locations within the subset of locations.

Abstract: An apparatus comprises memory access circuitry to access a memory system; a plurality of memory mapped registers, including at least an insert register and a producer pointer register; and control circuitry to perform an insert operation in response to receipt of an insert request from a requester device sharing access to the memory system. The insert request specifies an address mapped to the insert register and an indication of a payload. The insert operation includes controlling the memory access circuitry to write the payload to a location in the memory system selected based on a producer pointer value stored in the producer pointer register, and updating the producer pointer register to increment the producer pointer value.

Abstract: A data processing system is provided comprising a cache system configured to transfer data between a processor and memory system. The cache system comprises a cache. When a block of data that is stored in the memory in a compressed form is to be loaded into the cache, the block of data is stored into a group of one or more cache lines of the cache and the associated compression metadata for the compressed block of data is provided as separate side band data.

Abstract: Apparatus for data processing and a method of data processing are provided. Address translation storage stores address translations between first set addresses and second set addresses, and responds to a request comprising a first set address to return a response comprising a second set address if the required address translation is currently stored therein. If it is not the request is forwarded towards memory in a memory hierarchy. A pending request storage stores entries for received requests and in response to reception of the request, if a stored entry for a previous request indicates that the previous request has been forwarded towards the memory and an expected response to the previous request will provide the address translation, intercepts the request to delay its reception by the address translation storage. Bandwidth pressure on the address translation storage is thus relieved.

Abstract: Requester circuitry 4 issues an access request specifying a target physical address (PA) and a target physical address space (PAS) identifier identifying a target PAS. Prior to a point of physical aliasing (PoPA), a pre-PoPA memory system component 24, 8 treats aliasing PAs from different PASs which actually correspond to the same memory system resource as if they correspond to different memory system resources. A post-PoPA memory system component 6 treats the aliasing PAs as referring to the same memory system resource. When the target PA and target PAS of a read-if-hit-pre-PoPA request hit in a pre-PoPA cache 24, a data response is returned to the requester circuitry 4. If the read-if-hit-pre-PoPA request misses in the pre-PoPA cache 24, a no-data response is returned. The read-if-hit-pre-PoPA request is safe to issue speculatively while waiting for security checks to be performed, improving performance.

Abstract: The present disclosure advantageously provides a memory management unit and methods for invalidating cache lines in address translation caches. The memory management unit has one or more address translation caches, and each address translation cache has a plurality of cache lines. The memory management unit receives transactions from a source of transactions. The transactions include, inter alia, memory transactions and a set-aside translation transaction. The memory transactions include at least a first memory transaction and a last memory transaction, and each memory transaction includes the same virtual memory address and the same translation context identifier. The set-aside translation transaction also includes the same virtual memory address and the same translation context identifier.

Abstract: A type of translation lookaside buffer (TLB) invalidation instruction is described which specifically targets a first type of TLB which stores combined stage-1-and-2 entries which depend on both stage 1 translation data and the stage 2 translation data, and which is configured to ignore a TLB invalidation command which invalidates based on a first set of one or more invalidation conditions including an address-based invalidation condition depending on matching of intermediate address. A second type of TLB other than the first type ignores the invalidation command triggered by the first type of TLB invalidation instruction. This approach helps to limit the performance impact of stage 2 invalidations in systems supporting a combined stage-1-and-2 TLB which cannot invalidate by intermediate address.

Abstract: An apparatus comprises transaction handling circuitry to issue memory access transactions, each memory access transaction specifying an epoch identifier indicative of a current epoch in which the memory access transaction is issued; transaction tracking circuitry to track, for each of at least two epochs, a number of outstanding memory access transactions issued in that epoch; barrier termination circuitry to signal completion of a barrier termination command when the transaction tracking circuitry indicates that there are no outstanding memory access transactions remaining which were issued in one or more epochs preceding a barrier point; and epoch changing circuitry to change the current epoch to a next epoch, in response to a barrier point signal representing said barrier point. This helps to reduce the circuit area overhead for tracking completion of memory access transactions preceding a barrier point.