/* * Copyright (c) 2011-2015, 2017 ARM Limited * All rights reserved * * The license below extends only to copyright in the software and shall * not be construed as granting a license to any other intellectual * property including but not limited to intellectual property relating * to a hardware implementation of the functionality of the software * licensed hereunder. You may use the software subject to the license * terms below provided that you ensure that this notice is replicated * unmodified and in its entirety in all distributions of the software, * modified or unmodified, in source code or in binary form. * * Copyright (c) 2002-2005 The Regents of The University of Michigan * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer; * redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution; * neither the name of the copyright holders nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * Authors: Ron Dreslinski * Ali Saidi * Andreas Hansson * William Wang */ /** * @file * Declaration of a coherent crossbar. */ #ifndef __MEM_COHERENT_XBAR_HH__ #define __MEM_COHERENT_XBAR_HH__ #include #include #include "mem/snoop_filter.hh" #include "mem/xbar.hh" #include "params/CoherentXBar.hh" /** * A coherent crossbar connects a number of (potentially) snooping * masters and slaves, and routes the request and response packets * based on the address, and also forwards all requests to the * snoopers and deals with the snoop responses. * * The coherent crossbar can be used as a template for modelling QPI, * HyperTransport, ACE and coherent OCP buses, and is typically used * for the L1-to-L2 buses and as the main system interconnect. @sa * \ref gem5MemorySystem "gem5 Memory System" */ class CoherentXBar : public BaseXBar { protected: /** * Declare the layers of this crossbar, one vector for requests, * one for responses, and one for snoop responses */ std::vector reqLayers; std::vector respLayers; std::vector snoopLayers; /** * Declaration of the coherent crossbar slave port type, one will * be instantiated for each of the master ports connecting to the * crossbar. */ class CoherentXBarSlavePort : public QueuedSlavePort { private: /** A reference to the crossbar to which this port belongs. */ CoherentXBar &xbar; /** A normal packet queue used to store responses. */ RespPacketQueue queue; public: CoherentXBarSlavePort(const std::string &_name, CoherentXBar &_xbar, PortID _id) : QueuedSlavePort(_name, &_xbar, queue, _id), xbar(_xbar), queue(_xbar, *this) { } protected: /** * When receiving a timing request, pass it to the crossbar. */ virtual bool recvTimingReq(PacketPtr pkt) { return xbar.recvTimingReq(pkt, id); } /** * When receiving a timing snoop response, pass it to the crossbar. */ virtual bool recvTimingSnoopResp(PacketPtr pkt) { return xbar.recvTimingSnoopResp(pkt, id); } /** * When receiving an atomic request, pass it to the crossbar. */ virtual Tick recvAtomic(PacketPtr pkt) { return xbar.recvAtomic(pkt, id); } /** * When receiving a functional request, pass it to the crossbar. */ virtual void recvFunctional(PacketPtr pkt) { xbar.recvFunctional(pkt, id); } /** * Return the union of all adress ranges seen by this crossbar. */ virtual AddrRangeList getAddrRanges() const { return xbar.getAddrRanges(); } }; /** * Declaration of the coherent crossbar master port type, one will be * instantiated for each of the slave interfaces connecting to the * crossbar. */ class CoherentXBarMasterPort : public MasterPort { private: /** A reference to the crossbar to which this port belongs. */ CoherentXBar &xbar; public: CoherentXBarMasterPort(const std::string &_name, CoherentXBar &_xbar, PortID _id) : MasterPort(_name, &_xbar, _id), xbar(_xbar) { } protected: /** * Determine if this port should be considered a snooper. For * a coherent crossbar master port this is always true. * * @return a boolean that is true if this port is snooping */ virtual bool isSnooping() const { return true; } /** * When receiving a timing response, pass it to the crossbar. */ virtual bool recvTimingResp(PacketPtr pkt) { return xbar.recvTimingResp(pkt, id); } /** * When receiving a timing snoop request, pass it to the crossbar. */ virtual void recvTimingSnoopReq(PacketPtr pkt) { return xbar.recvTimingSnoopReq(pkt, id); } /** * When receiving an atomic snoop request, pass it to the crossbar. */ virtual Tick recvAtomicSnoop(PacketPtr pkt) { return xbar.recvAtomicSnoop(pkt, id); } /** * When receiving a functional snoop request, pass it to the crossbar. */ virtual void recvFunctionalSnoop(PacketPtr pkt) { xbar.recvFunctionalSnoop(pkt, id); } /** When reciving a range change from the peer port (at id), pass it to the crossbar. */ virtual void recvRangeChange() { xbar.recvRangeChange(id); } /** When reciving a retry from the peer port (at id), pass it to the crossbar. */ virtual void recvReqRetry() { xbar.recvReqRetry(id); } }; /** * Internal class to bridge between an incoming snoop response * from a slave port and forwarding it through an outgoing slave * port. It is effectively a dangling master port. */ class SnoopRespPort : public MasterPort { private: /** The port which we mirror internally. */ QueuedSlavePort& slavePort; public: /** * Create a snoop response port that mirrors a given slave port. */ SnoopRespPort(QueuedSlavePort& slave_port, CoherentXBar& _xbar) : MasterPort(slave_port.name() + ".snoopRespPort", &_xbar), slavePort(slave_port) { } /** * Override the sending of retries and pass them on through * the mirrored slave port. */ void sendRetryResp() { // forward it as a snoop response retry slavePort.sendRetrySnoopResp(); } /** * Provided as necessary. */ void recvReqRetry() { panic("SnoopRespPort should never see retry\n"); } /** * Provided as necessary. */ bool recvTimingResp(PacketPtr pkt) { panic("SnoopRespPort should never see timing response\n"); return false; } }; std::vector snoopRespPorts; std::vector snoopPorts; /** * Store the outstanding requests that we are expecting snoop * responses from so we can determine which snoop responses we * generated and which ones were merely forwarded. */ std::unordered_set outstandingSnoop; /** * Store the outstanding cache maintenance that we are expecting * snoop responses from so we can determine when we received all * snoop responses and if any of the agents satisfied the request. */ std::unordered_map outstandingCMO; /** * Keep a pointer to the system to be allow to querying memory system * properties. */ System *system; /** A snoop filter that tracks cache line residency and can restrict the * broadcast needed for probes. NULL denotes an absent filter. */ SnoopFilter *snoopFilter; /** Cycles of snoop response latency.*/ const Cycles snoopResponseLatency; /** Is this crossbar the point of coherency? **/ const bool pointOfCoherency; /** Is this crossbar the point of unification? **/ const bool pointOfUnification; /** * Upstream caches need this packet until true is returned, so * hold it for deletion until a subsequent call */ std::unique_ptr pendingDelete; /** Function called by the port when the crossbar is recieving a Timing request packet.*/ bool recvTimingReq(PacketPtr pkt, PortID slave_port_id); /** Function called by the port when the crossbar is recieving a Timing response packet.*/ bool recvTimingResp(PacketPtr pkt, PortID master_port_id); /** Function called by the port when the crossbar is recieving a timing snoop request.*/ void recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id); /** Function called by the port when the crossbar is recieving a timing snoop response.*/ bool recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id); /** Timing function called by port when it is once again able to process * requests. */ void recvReqRetry(PortID master_port_id); /** * Forward a timing packet to our snoopers, potentially excluding * one of the connected coherent masters to avoid sending a packet * back to where it came from. * * @param pkt Packet to forward * @param exclude_slave_port_id Id of slave port to exclude */ void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id) { forwardTiming(pkt, exclude_slave_port_id, snoopPorts); } /** * Forward a timing packet to a selected list of snoopers, potentially * excluding one of the connected coherent masters to avoid sending a packet * back to where it came from. * * @param pkt Packet to forward * @param exclude_slave_port_id Id of slave port to exclude * @param dests Vector of destination ports for the forwarded pkt */ void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id, const std::vector& dests); /** Function called by the port when the crossbar is recieving a Atomic transaction.*/ Tick recvAtomic(PacketPtr pkt, PortID slave_port_id); /** Function called by the port when the crossbar is recieving an atomic snoop transaction.*/ Tick recvAtomicSnoop(PacketPtr pkt, PortID master_port_id); /** * Forward an atomic packet to our snoopers, potentially excluding * one of the connected coherent masters to avoid sending a packet * back to where it came from. * * @param pkt Packet to forward * @param exclude_slave_port_id Id of slave port to exclude * * @return a pair containing the snoop response and snoop latency */ std::pair forwardAtomic(PacketPtr pkt, PortID exclude_slave_port_id) { return forwardAtomic(pkt, exclude_slave_port_id, InvalidPortID, snoopPorts); } /** * Forward an atomic packet to a selected list of snoopers, potentially * excluding one of the connected coherent masters to avoid sending a packet * back to where it came from. * * @param pkt Packet to forward * @param exclude_slave_port_id Id of slave port to exclude * @param source_master_port_id Id of the master port for snoops from below * @param dests Vector of destination ports for the forwarded pkt * * @return a pair containing the snoop response and snoop latency */ std::pair forwardAtomic(PacketPtr pkt, PortID exclude_slave_port_id, PortID source_master_port_id, const std::vector& dests); /** Function called by the port when the crossbar is recieving a Functional transaction.*/ void recvFunctional(PacketPtr pkt, PortID slave_port_id); /** Function called by the port when the crossbar is recieving a functional snoop transaction.*/ void recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id); /** * Forward a functional packet to our snoopers, potentially * excluding one of the connected coherent masters to avoid * sending a packet back to where it came from. * * @param pkt Packet to forward * @param exclude_slave_port_id Id of slave port to exclude */ void forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id); /** * Determine if the crossbar should sink the packet, as opposed to * forwarding it, or responding. */ bool sinkPacket(const PacketPtr pkt) const; /** * Determine if the crossbar should forward the packet, as opposed to * responding to it. */ bool forwardPacket(const PacketPtr pkt); /** * Determine if the packet's destination is the memory below * * The memory below is the destination for a cache mainteance * operation to the Point of Coherence/Unification if this is the * Point of Coherence/Unification. * * @param pkt The processed packet * * @return Whether the memory below is the destination for the packet */ bool isDestination(const PacketPtr pkt) const { return (pkt->req->isToPOC() && pointOfCoherency) || (pkt->req->isToPOU() && pointOfUnification); } Stats::Scalar snoops; Stats::Scalar snoopTraffic; Stats::Distribution snoopFanout; public: virtual void init(); CoherentXBar(const CoherentXBarParams *p); virtual ~CoherentXBar(); virtual void regStats(); }; #endif //__MEM_COHERENT_XBAR_HH__