Intel Corporation

Ampere Computing LLC

Benjamin C Chaffin

Roger Gramunt

Francis X Mckeen

Bryant E Bigbee

Lawrence O Smith

Michael Cornaby

Ramon Matas

Bret Leslie Toll

Jason W Brandt

Alexey Suprun

Rammohan Padmanabhan

Neal S Moyer

Gilbert A Neiger

Rajesh M Sankaran

Avinash Sodani

Raghunandan Makaram

H Peter Anvin

James B Crossland

Michael Mishaeli

Asit K Mallick

Jonathan Cannon Hall

Aditya Kesiraju

Julio Gago

Jonathan Christopher Perry

Chung-Lun Chan

Matthew G Smith

Jesus Corbal

Andrew F Glew

Dennis Ryan Bradford

Jonathan D Combs

Nagi Aboulenein

Taraneh Bahrami

Richard James Shannon

Rohan Sharma

Jesus Corbal San Adrian

Robert J Kyanko

George Van Horn Leming, Iii

Thomas B Maciukenas

Michael Stephen Chin

Jacob Daniel Morgan

Michael S Yang

Bharadwaj Coimbatore Krishnamurthy

David Nuechterlein

Michael Spradling

Allan Mcbride Rudwick

Vikram S Sundaram

Gerardo A Fernandez

Aspects disclosed in the detailed description include performing snoop filter replacement based on history-augmented victimization priority values of snoop filter entries in processor-based devices. In an exemplary aspect, a Fully Coherent Home Node (HN-F) circuit of a processor-based device receives, from a Fully Coherent Request Node (RN-F) circuit, a transaction request comprising a memory address. The HN-F circuit determines a victimization priority value based on the transaction request. Upon determining that no snoop filter entry in a snoop filter of the HN-F circuit stores the memory address and determining that no snoop filter entries are available for allocation, the HN-F circuit selects a target snoop filter entry that stores a highest victimization priority value among the snoop filter entries, writes the current memory address of the target snoop filter back to memory, and then stores the memory address and the victimization priority value in the target snoop filter entry.

Performing snoop filter replacement based on history-augmented victimization priority values of snoop filter entries in processor-based devices

A compute node capable of enhanced performance and/or energy savings is proposed. The proposed compute node may check whether a last instruction of a first group—retrieved in a first decode cycle—is potentially a fusible instruction. If so, the proposed compute node may refrain from decoding the last instruction in the first decode cycle. Instead, the proposed compute node may determine if a first instruction of a second group of instructions retrieved in a second decode cycle (subsequent to the first decode cycle) is fusible with the last instruction of the first group. If so, the two instructions may be fused to a single micro-operation.

Mechanism for instruction fusion

Performing instruction fetch pipeline synchronization (IFPS) in processor-based devices is disclosed herein. In some exemplary aspects, a processor-based device provides multiple processors including a remote processor. The remote processor receives, from an issuing processor, a translation lookaside buffer (TLB) invalidation (TLBI) request indicating a request to invalidate an address translation, and subsequently receives an IFPS request from the issuing processor. The remote processor determines that any previously received TLBI requests including the most recent TLBI request have completed. Upon receiving the IFPS request, the remote processor determines that all instructions within a fetch pipeline portion that were potentially fetched using address translations older than the IFPS request have proceeded from the fetch pipeline portion of an instruction processing circuit to an execution pipeline portion of the instruction processing circuit. The remote processor then performs a data synchronization barrier (DSB) operation, and issues a synchronization acknowledgement to the issuing processor.

Performing instruction fetch pipeline synchronization (IFPS) in processor-based devices

Mitigation of return stack buffer side channel attacks in a processor. Detecting a side channel attack or a fault in a return from a function call in the processor includes receiving a return exception level indication (or e.g., a return security level indication) indicating the exception level associated with the return and comparing the exception level associated with the return to the exception level (or security level) associated with the return address. The return exception level indicator may be received in conjunction with a return indication. The processing circuit accesses the first entry of the return stack buffer, which indicates the return address of the function call, and also accesses an exception level associated with the return address. The processing circuit compares the exception level associated with the return address to the exception level associated with the return to determine whether to use the return address in a prediction of instruction flow.

Mitigation of return stack buffer side channel attacks in a processor

A processor of an aspect includes a decode unit to decode a user-level suspend thread instruction that is to indicate a first alternate state. The processor also includes an execution unit coupled with the decode unit. The execution unit is to perform the instruction at a user privilege level. The execution unit in response to the instruction, is to: (a) suspend execution of a user-level thread, from which the instruction is to have been received; (b) transition a logical processor, on which the user-level thread was to have been running, to the indicated first alternate state; and (c) resume the execution of the user-level thread, when the logical processor is in the indicated first alternate state, with a latency that is to be less than half a latency that execution of a thread can be resumed when the logical processor is in a halt processor power state.

Methods, apparatus, and instructions for user-level thread suspension

A data processing system includes a store datapath configured to perform tag checking in a store operation to a store address associated with a cache line in a memory. The store datapath includes a cache lookup circuit configured to pre-load a store cache line that is to be updated in the store operation, wherein the store cache line comprises the cache line in the memory to be updated in the store operation. The store datapath also includes a tag check circuit configured to compare a store address tag associated with the store address to a store operation tag associated with the store operation. The data processing system may include a load datapath configured to perform tag checking in a load operation from a load cache line in the memory by comparing a load address tag associated with the load address to a load operation tag associated with the load operation.

Method, apparatus, and system for run-time checking of memory tags in a processor-based system

Methods, apparatus, and instructions for user level thread suspension

A processor includes a logic for stateless capture of data linear addresses (DLA) during precise event based sampling (PEBS) for an out-of-order execution engine. The engine may include a PEBS unit with logic to increment a counter each time an instance of a designated micro-op is retired a reorder buffer, capture output DLA referenced by an instance of the micro-op that executes after the counter overflows, set a captured bit associated with a reorder buffer identifier for the instance of the micro-op, and store a PEBS record in a debug storage when the instance of the micro-op is retired from the reorder buffer. The designated micro-op references a DLA of a memory accessible to the processor.

Stateless capture of data linear addresses during precise event based sampling

Instructions and logic provide user-level thread synchronization with MONITOR and MWAIT instructions. One or more model specific registers (MSRs) in a processor may be configured in a first execution state to specify support of a user-level thread synchronization architecture. Embodiments include multiple hardware threads or processing cores, corresponding monitored address state storage to store a last monitored address for each of a plurality of execution threads that issues a MONITOR request, cache memory to record MONITOR requests and associated states for addresses of memory storage locations, and responsive to receipt of an MWAIT request for the address, to record an associated wait-to-trigger state of monitored addresses for execution cores associated with an MWAIT request; wherein the execution core is to transition a requesting thread to an optimized sleep state responsive to the receipt of said MWAIT request when said one or more MSRs are configured in the first execution state.

Method and apparatus for user-level thread synchronization with a monitor and MWAIT architecture

In one embodiment, a processor includes a frontend unit having an instruction decoder to receive and to decode instructions of a plurality of threads, an execution unit coupled to the instruction decoder to receive and execute the decoded instructions, and an instruction retirement unit having a retirement logic to receive the instructions from the execution unit and to retire the instructions associated with one or more of the threads that have an instruction or an event pending to be retired. The instruction retirement unit includes a thread arbitration logic to select one of the threads at a time and to dispatch the selected thread to the retirement logic for retirement processing.

Scalable event handling in multi-threaded processor cores

An apparatus and method for efficiently managing the architectural state of a processor. For example, one embodiment of a processor comprises: a source mask register to be logically subdivided into at least a first portion to store a usable portion of a mask value and a second portion to store an indication of whether the usable portion of the mask value has been updated; a control register to store an unusable portion of the mask value; architectural state management logic to read the indication to determine whether the mask value has been updated prior to performing a store operation, wherein if the mask value has been updated, then the architectural state management logic is to read the usable portion of the mask value from the first portion of the source mask register and zero out bits of the unusable portion of the mask value to generate a final mask value to be saved to memory, and wherein if the mask value has not been updated, then the architectural state management logic is to concatenate the usable portion of the mask value with the unusable portion of the mask value read from the control register to generate a final mask value to be saved to memory.

Method and apparatus for efficiently managing architectural register state of a processor

Exemplary aspects are directed toward resolving fault suppression in hardware, which at the same time does not incur a performance hit. For example, when multiple instructions are executing simultaneously, a mask can specify which elements need not be executed. If the mask is disabled, those elements do not need to be executed. A determination is then made as to whether a fault happens in one of the elements that have been disabled. If there is a fault in one of the elements that has been disabled, a state machine re-fetches the instructions in a special mode. More specifically, the state machine determines if the fault is on a disabled element, and if the fault is on a disabled element, then the state machine specifies that the fault should be ignored. If during the first execution there was no mask, if there is an error present during execution, then the element is re-run with the mask to see if the error is a 'real' fault.

Memory fault suppression via re-execution and hardware FSM

In some implementations, a processor may include a data structure, such as a translation lookaside buffer, that includes an entry containing first mapping information having a virtual address and a first context associated with a first thread. Control logic may receive a request for second mapping information having the virtual address and a second context associated with a second thread. The control logic may determine whether the second mapping information associated with the second context is equivalent to the first mapping information in the entry of the data structure. If the second mapping information is equivalent to the first mapping information, the control logic may associate the second thread with the first mapping information contained in the entry of the data structure to share the entry between the first thread and the second thread.

Sharing TLB mappings between contexts

A platform and method for secure handling of events in an isolated environment. A processor executing in isolated execution 'IsoX' mode may leak data when an event occurs as a result of the event being handled in a traditional manner based on the exception vector. By defining a class of events to be handled in IsoX mode, and switching between a normal memory map and an IsoX memory map dynamically in response to receipt of an event of the class, data security may be maintained in the face of such events.

Mechanism to handle events in a machine with isolated execution

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Portland, OR, United States of America

Benjamin C Chaffin