Mips Tech Limited

Redback Networks Inc.

Imagination Technologies Limited

Telefonaktiebolaget Lm Ericsson (Publ)

Advanced Micro Devices Corporation

Arm Finance Overseas Limited

Other

Mips Technologies, Inc.

Ranjit Joseph Rozario

Sanjay Patel

Ravikrishna Cherukuri

Ranganathan Sudhakar

Brian Alleyne

Michael Feng

Edmund C Chen

Edmund G Chen

Sridhar P Subramanian

Edward Ho

Thomas C Yip

Patrick Wang

Sun Den Chen

Stephen Chow

Gary Scott Delp

Ramanathan Lakshmikanthan

Robert G Hathaway

Era Kasturia Nangia

Debasish Chandra

Scott Waldron

James Hippisley Robinson

Sudhakar Ranganathan

Todd D Basso

Andrew F Glew

Srivi Dhruvanarayan

Ravikrishna V Cherukuri

Aspects relate to Input/Output (IO) Memory Management Units (MMUs) that include hardware structures for implementing virtualization. Some implementations allow guests to setup and maintain device IO tables within memory regions to which those guests have been given permissions by a hypervisor. Some implementations provide hardware page table walking capability within the IOMMU, while other implementations provide static tables. Such static tables may be maintained by a hypervisor on behalf of guests. Some implementations reduce a frequency of interrupts or invocation of hypervisor by allowing transactions to be setup by guests without hypervisor involvement within their assigned device IO regions. Devices may communicate with IOMMU to setup the requested memory transaction, and completion thereof may be signaled to the guest without hypervisor involvement. Various other aspects will be evident from the disclosure.

Virtualized-in-hardware input output memory management

In an aspect, a processor supports modeless execution of 64 bit and 32 bit instructions. A Load/Store Unit (LSU) decodes an instruction that without explicit opcode data indicating whether the instruction is to operate in a 32 or 64 bit memory address space. LSU treats the instruction either as a 32 or 64 bit instruction in dependence on values in an upper 32 bits of one or more 64 bit operands supplied to create an effective address in memory. In an example, a 4 GB space addressed by 32-bit memory space is divided between upper and lower portions of a 64-bit address space, such that a 32-bit instruction is differentiated from a 64-bit instruction in dependence on whether an upper 32 bits of one or more operands is either all binary 1 or all binary 0. Such a processor may support decoding of different arithmetic instructions for 32-bit and 64-bit operations.

Modeless instruction execution with 64/32-bit addressing

A system and method process atomic instructions. A processor system includes a load store unit (LSU), first and second registers, a memory interface, and a main memory. In response to a load link (LL) instruction, the LSU loads first data from memory into the first register and sets an LL bit (LLBIT) to indicate a sequence of atomic instructions is being executed. The LSU further loads second data from memory into the second register in response to a load (LD) instruction. The LSU places a value of the second register into the memory interface in response to a store conditional coupled (SCX) instruction. When the LLBIT is set and in response to a store (SC) instruction, the LSU places a value of the second register into the memory interface and commits the first and second register values in the memory interface into the main memory when the LLBIT is set.

Processors supporting atomic writes to multiword memory locations and methods

Hardware virtualized input output memory management unit

Embodiments disclosed pertain to apparatuses, systems, and methods for Translation Lookaside Buffers (TLBs) that support visualization and multi-threading. Disclosed embodiments pertain to a TLB that includes a content addressable memory (CAM) with variable page size entries and a set associative memory with fixed page size entries. The CAM may include: a first set of logically contiguous entry locations, wherein the first set comprises a plurality of subsets, and each subset comprises logically contiguous entry locations for exclusive use of a corresponding virtual processing element (VPE); and a second set of logically contiguous entry locations, distinct from the first set, where the entry locations in the second set may be shared among available VPEs. The set associative memory may comprise a third set of logically contiguous entry locations shared among the available VPEs distinct from the first and second set of entry locations.

Translation lookaside buffer

A method includes assigning unique guest identifications to different guests, specifying an address region and permissions for the different guests and controlling a guest jump from one physical memory segment to a second physical memory segment through operational permissions defined in a root memory management unit that supports guest isolation and protection.

Embedded processor with virtualized security controls using guest identifications, a common kernel address space and operational permissions

In one aspect, a processor has a register file, a private Level 1 (L1) cache, and an interface to a shared memory hierarchy (e.g., an Level 2 (L2) cache and so on). The processor has a Load Store Unit (LSU) that handles decoded load and store instructions. The processor may support out of order and multi-threaded execution. As store instructions arrive at the LSU for processing, the LSU determines whether a counter, from a set of counters, is allocated to a cache line affected by each store. If not, the LSU allocates a counter. If so, then the LSU updates the counter. Also, in response to a store instruction, affecting a cache line neighboring a cache line that has a counter that meets a criteria, the LSU characterizes that store instruction as one to be effected without obtaining ownership of the effected cache line, and provides that store to be serviced by an element of the shared memory hierarchy.

Processors and methods for cache sparing stores

Embodiments disclosed pertain to apparatuses, systems, and methods for Translation Lookaside Buffers (TLBs) that support virtualization and multi-threading. Disclosed embodiments pertain to a TLB that includes a content addressable memory (CAM) with variable page size entries and a set associative memory with fixed page size entries. The CAM may include: a first set of logically contiguous entry locations, wherein the first set comprises a plurality of subsets, and each subset comprises logically contiguous entry locations for exclusive use of a corresponding virtual processing element (VPE); and a second set of logically contiguous entry locations, distinct from the first set, where the entry locations in the second set may be shared among available VPEs. The set associative memory may comprise a third set of logically contiguous entry locations shared among the available VPEs distinct from the first and second set of entry locations.

An integrated circuit implements a multistage processing pipeline, where control is passed in the pipeline with data to be processed according to the control. At least some of the different pipeline stages can be implemented by different circuits, being clocked at different frequencies. These frequencies may change dynamically during operation of the integrated circuit. Control and data to be processed according to such control can be offset from each other in the pipeline; e.g., control can precede data by a pre-set number of clock events. To cross a clock domain, control and data can be temporarily stored in respective FIFOs. Reading of control by the destination domain is delayed by a delay amount determined so that reading of control and data can be offset from each other by a minimum number of clock events of the destination domain clock, and control is read before data is available for reading.

Crossing pipelined data between circuitry in different clock domains

In one aspect, a pipelined ECC-protected cache access method and apparatus provides that during a normal operating mode, for a given cache transaction, a tag comparison action and a data RAM read are performed speculatively in a time during which an ECC calculation occurs. If a correctable error occurs, the tag comparison action and data RAM are repeated and an error mode is entered. Subsequent transactions are processed by performing the ECC calculation, without concurrent speculative actions, and a tag comparison and read are performed using only the tag data available after the ECC calculation. A reset to normal mode is effected by detecting a gap between transactions that is sufficient to avoid a conflict for use of tag comparison circuitry for an earlier transaction having a repeated tag comparison and a later transaction having a speculative tag comparison.

Pipelined ECC-protected memory access

A computer readable storage medium includes executable instructions to define a processor with guest mode control registers supporting guest mode operating behavior defined by guest context specified in the guest mode control registers. The guest mode control registers include a control bit to specify a guest access blocked register state and a shared register state. Root mode control registers support root mode operating behavior defined by root context specified in the root mode control registers. The root mode control registers include control bits to enable replicated register state access and shared register state access. The guest context and the root context support virtualization of hardware resources such that multiple operating systems supporting multiple applications are executed by the hardware resources.

Apparatus and method for guest and root register sharing in a virtual machine

Embodiments of the invention include a method for avoiding memory bandwidth utilization during packet processing. The packet processing core receives a plurality of packets. The packet processing core identifies the packet's quality of service (QoS) descriptor. The packet processing core determines that at least one packet should be moved to an off-chip packet stored prior to the packet being transmitted to the egress port. The packet processing core bases that determination, at least in part, on the packet's QoS descriptor. The packet processing core moves the determined packets to the off-chip packet store. The packet processing core determines that at least one packet should not be moved to the off-chip packet store prior to the packet being transmitted to the egress port. This determination is also made, at least in part, based on the packet's QoS descriptor.

On-chip packet cut-through

Growing community of inventors

San Jose, CA, United States of America

Ranjit Joseph Rozario