/*
- * Copyright (c) 2004-2005 The Regents of The University of Michigan
+ * Copyright (c) 2010-2015 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
+ * Copyright (c) 2010,2015 Advanced Micro Devices, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Erik Hallnor
+ * Dave Greene
+ * Nathan Binkert
* Steve Reinhardt
- * Lisa Hsu
- * Kevin Lim
+ * Ron Dreslinski
+ * Andreas Sandberg
*/
/**
* @file
- * Cache template instantiations.
+ * Cache definitions.
*/
-#include "mem/config/cache.hh"
+#include "mem/cache/cache.hh"
-#if defined(USE_CACHE_LRU)
-#include "mem/cache/tags/lru.hh"
-#endif
+#include "base/misc.hh"
+#include "base/types.hh"
+#include "debug/Cache.hh"
+#include "debug/CachePort.hh"
+#include "debug/CacheTags.hh"
+#include "debug/CacheVerbose.hh"
+#include "mem/cache/blk.hh"
+#include "mem/cache/mshr.hh"
+#include "mem/cache/prefetch/base.hh"
+#include "sim/sim_exit.hh"
-#if defined(USE_CACHE_FALRU)
-#include "mem/cache/tags/fa_lru.hh"
-#endif
+Cache::Cache(const CacheParams *p)
+ : BaseCache(p, p->system->cacheLineSize()),
+ tags(p->tags),
+ prefetcher(p->prefetcher),
+ doFastWrites(true),
+ prefetchOnAccess(p->prefetch_on_access),
+ clusivity(p->clusivity),
+ writebackClean(p->writeback_clean),
+ tempBlockWriteback(nullptr),
+ writebackTempBlockAtomicEvent(this, false,
+ EventBase::Delayed_Writeback_Pri)
+{
+ tempBlock = new CacheBlk();
+ tempBlock->data = new uint8_t[blkSize];
-#if defined(USE_CACHE_IIC)
-#include "mem/cache/tags/iic.hh"
-#endif
+ cpuSidePort = new CpuSidePort(p->name + ".cpu_side", this,
+ "CpuSidePort");
+ memSidePort = new MemSidePort(p->name + ".mem_side", this,
+ "MemSidePort");
-#if defined(USE_CACHE_SPLIT)
-#include "mem/cache/tags/split.hh"
-#endif
+ tags->setCache(this);
+ if (prefetcher)
+ prefetcher->setCache(this);
+}
-#if defined(USE_CACHE_SPLIT_LIFO)
-#include "mem/cache/tags/split_lifo.hh"
-#endif
+Cache::~Cache()
+{
+ delete [] tempBlock->data;
+ delete tempBlock;
-#include "mem/cache/cache_impl.hh"
+ delete cpuSidePort;
+ delete memSidePort;
+}
-// Template Instantiations
-#ifndef DOXYGEN_SHOULD_SKIP_THIS
+void
+Cache::regStats()
+{
+ BaseCache::regStats();
+}
+void
+Cache::cmpAndSwap(CacheBlk *blk, PacketPtr pkt)
+{
+ assert(pkt->isRequest());
-#if defined(USE_CACHE_FALRU)
-template class Cache<FALRU>;
-#endif
+ uint64_t overwrite_val;
+ bool overwrite_mem;
+ uint64_t condition_val64;
+ uint32_t condition_val32;
-#if defined(USE_CACHE_IIC)
-template class Cache<IIC>;
-#endif
+ int offset = tags->extractBlkOffset(pkt->getAddr());
+ uint8_t *blk_data = blk->data + offset;
-#if defined(USE_CACHE_LRU)
-template class Cache<LRU>;
-#endif
+ assert(sizeof(uint64_t) >= pkt->getSize());
+
+ overwrite_mem = true;
+ // keep a copy of our possible write value, and copy what is at the
+ // memory address into the packet
+ pkt->writeData((uint8_t *)&overwrite_val);
+ pkt->setData(blk_data);
+
+ if (pkt->req->isCondSwap()) {
+ if (pkt->getSize() == sizeof(uint64_t)) {
+ condition_val64 = pkt->req->getExtraData();
+ overwrite_mem = !std::memcmp(&condition_val64, blk_data,
+ sizeof(uint64_t));
+ } else if (pkt->getSize() == sizeof(uint32_t)) {
+ condition_val32 = (uint32_t)pkt->req->getExtraData();
+ overwrite_mem = !std::memcmp(&condition_val32, blk_data,
+ sizeof(uint32_t));
+ } else
+ panic("Invalid size for conditional read/write\n");
+ }
+
+ if (overwrite_mem) {
+ std::memcpy(blk_data, &overwrite_val, pkt->getSize());
+ blk->status |= BlkDirty;
+ }
+}
+
+
+void
+Cache::satisfyCpuSideRequest(PacketPtr pkt, CacheBlk *blk,
+ bool deferred_response, bool pending_downgrade)
+{
+ assert(pkt->isRequest());
+
+ assert(blk && blk->isValid());
+ // Occasionally this is not true... if we are a lower-level cache
+ // satisfying a string of Read and ReadEx requests from
+ // upper-level caches, a Read will mark the block as shared but we
+ // can satisfy a following ReadEx anyway since we can rely on the
+ // Read requester(s) to have buffered the ReadEx snoop and to
+ // invalidate their blocks after receiving them.
+ // assert(!pkt->needsWritable() || blk->isWritable());
+ assert(pkt->getOffset(blkSize) + pkt->getSize() <= blkSize);
+
+ // Check RMW operations first since both isRead() and
+ // isWrite() will be true for them
+ if (pkt->cmd == MemCmd::SwapReq) {
+ cmpAndSwap(blk, pkt);
+ } else if (pkt->isWrite()) {
+ // we have the block in a writable state and can go ahead,
+ // note that the line may be also be considered writable in
+ // downstream caches along the path to memory, but always
+ // Exclusive, and never Modified
+ assert(blk->isWritable());
+ // Write or WriteLine at the first cache with block in writable state
+ if (blk->checkWrite(pkt)) {
+ pkt->writeDataToBlock(blk->data, blkSize);
+ }
+ // Always mark the line as dirty (and thus transition to the
+ // Modified state) even if we are a failed StoreCond so we
+ // supply data to any snoops that have appended themselves to
+ // this cache before knowing the store will fail.
+ blk->status |= BlkDirty;
+ DPRINTF(CacheVerbose, "%s for %s addr %#llx size %d (write)\n",
+ __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize());
+ } else if (pkt->isRead()) {
+ if (pkt->isLLSC()) {
+ blk->trackLoadLocked(pkt);
+ }
+
+ // all read responses have a data payload
+ assert(pkt->hasRespData());
+ pkt->setDataFromBlock(blk->data, blkSize);
+
+ // determine if this read is from a (coherent) cache, or not
+ // by looking at the command type; we could potentially add a
+ // packet attribute such as 'FromCache' to make this check a
+ // bit cleaner
+ if (pkt->cmd == MemCmd::ReadExReq ||
+ pkt->cmd == MemCmd::ReadSharedReq ||
+ pkt->cmd == MemCmd::ReadCleanReq ||
+ pkt->cmd == MemCmd::SCUpgradeFailReq) {
+ assert(pkt->getSize() == blkSize);
+ // special handling for coherent block requests from
+ // upper-level caches
+ if (pkt->needsWritable()) {
+ // sanity check
+ assert(pkt->cmd == MemCmd::ReadExReq ||
+ pkt->cmd == MemCmd::SCUpgradeFailReq);
+
+ // if we have a dirty copy, make sure the recipient
+ // keeps it marked dirty (in the modified state)
+ if (blk->isDirty()) {
+ pkt->setCacheResponding();
+ }
+ // on ReadExReq we give up our copy unconditionally,
+ // even if this cache is mostly inclusive, we may want
+ // to revisit this
+ invalidateBlock(blk);
+ } else if (blk->isWritable() && !pending_downgrade &&
+ !pkt->hasSharers() &&
+ pkt->cmd != MemCmd::ReadCleanReq) {
+ // we can give the requester a writable copy on a read
+ // request if:
+ // - we have a writable copy at this level (& below)
+ // - we don't have a pending snoop from below
+ // signaling another read request
+ // - no other cache above has a copy (otherwise it
+ // would have set hasSharers flag when
+ // snooping the packet)
+ // - the read has explicitly asked for a clean
+ // copy of the line
+ if (blk->isDirty()) {
+ // special considerations if we're owner:
+ if (!deferred_response) {
+ // respond with the line in Modified state
+ // (cacheResponding set, hasSharers not set)
+ pkt->setCacheResponding();
+
+ if (clusivity == Enums::mostly_excl) {
+ // if this cache is mostly exclusive with
+ // respect to the cache above, drop the
+ // block, no need to first unset the dirty
+ // bit
+ invalidateBlock(blk);
+ } else {
+ // if this cache is mostly inclusive, we
+ // keep the block in the Exclusive state,
+ // and pass it upwards as Modified
+ // (writable and dirty), hence we have
+ // multiple caches, all on the same path
+ // towards memory, all considering the
+ // same block writable, but only one
+ // considering it Modified
+
+ // we get away with multiple caches (on
+ // the same path to memory) considering
+ // the block writeable as we always enter
+ // the cache hierarchy through a cache,
+ // and first snoop upwards in all other
+ // branches
+ blk->status &= ~BlkDirty;
+ }
+ } else {
+ // if we're responding after our own miss,
+ // there's a window where the recipient didn't
+ // know it was getting ownership and may not
+ // have responded to snoops correctly, so we
+ // have to respond with a shared line
+ pkt->setHasSharers();
+ }
+ }
+ } else {
+ // otherwise only respond with a shared copy
+ pkt->setHasSharers();
+ }
+ }
+ } else {
+ // Upgrade or Invalidate
+ assert(pkt->isUpgrade() || pkt->isInvalidate());
+
+ // for invalidations we could be looking at the temp block
+ // (for upgrades we always allocate)
+ invalidateBlock(blk);
+ DPRINTF(CacheVerbose, "%s for %s addr %#llx size %d (invalidation)\n",
+ __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize());
+ }
+}
+
+
+/////////////////////////////////////////////////////
+//
+// MSHR helper functions
+//
+/////////////////////////////////////////////////////
+
+
+void
+Cache::markInService(MSHR *mshr, bool pending_modified_resp)
+{
+ markInServiceInternal(mshr, pending_modified_resp);
+}
+
+/////////////////////////////////////////////////////
+//
+// Access path: requests coming in from the CPU side
+//
+/////////////////////////////////////////////////////
+
+bool
+Cache::access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat,
+ PacketList &writebacks)
+{
+ // sanity check
+ assert(pkt->isRequest());
+
+ chatty_assert(!(isReadOnly && pkt->isWrite()),
+ "Should never see a write in a read-only cache %s\n",
+ name());
+
+ DPRINTF(CacheVerbose, "%s for %s addr %#llx size %d\n", __func__,
+ pkt->cmdString(), pkt->getAddr(), pkt->getSize());
+
+ if (pkt->req->isUncacheable()) {
+ DPRINTF(Cache, "%s%s addr %#llx uncacheable\n", pkt->cmdString(),
+ pkt->req->isInstFetch() ? " (ifetch)" : "",
+ pkt->getAddr());
+
+ // flush and invalidate any existing block
+ CacheBlk *old_blk(tags->findBlock(pkt->getAddr(), pkt->isSecure()));
+ if (old_blk && old_blk->isValid()) {
+ if (old_blk->isDirty() || writebackClean)
+ writebacks.push_back(writebackBlk(old_blk));
+ else
+ writebacks.push_back(cleanEvictBlk(old_blk));
+ tags->invalidate(old_blk);
+ old_blk->invalidate();
+ }
+
+ blk = NULL;
+ // lookupLatency is the latency in case the request is uncacheable.
+ lat = lookupLatency;
+ return false;
+ }
+
+ ContextID id = pkt->req->hasContextId() ?
+ pkt->req->contextId() : InvalidContextID;
+ // Here lat is the value passed as parameter to accessBlock() function
+ // that can modify its value.
+ blk = tags->accessBlock(pkt->getAddr(), pkt->isSecure(), lat, id);
+
+ DPRINTF(Cache, "%s%s addr %#llx size %d (%s) %s\n", pkt->cmdString(),
+ pkt->req->isInstFetch() ? " (ifetch)" : "",
+ pkt->getAddr(), pkt->getSize(), pkt->isSecure() ? "s" : "ns",
+ blk ? "hit " + blk->print() : "miss");
+
+
+ if (pkt->isEviction()) {
+ // We check for presence of block in above caches before issuing
+ // Writeback or CleanEvict to write buffer. Therefore the only
+ // possible cases can be of a CleanEvict packet coming from above
+ // encountering a Writeback generated in this cache peer cache and
+ // waiting in the write buffer. Cases of upper level peer caches
+ // generating CleanEvict and Writeback or simply CleanEvict and
+ // CleanEvict almost simultaneously will be caught by snoops sent out
+ // by crossbar.
+ std::vector<MSHR *> outgoing;
+ if (writeBuffer.findMatches(pkt->getAddr(), pkt->isSecure(),
+ outgoing)) {
+ assert(outgoing.size() == 1);
+ MSHR *wb_entry = outgoing[0];
+ assert(wb_entry->getNumTargets() == 1);
+ PacketPtr wbPkt = wb_entry->getTarget()->pkt;
+ assert(wbPkt->isWriteback());
+
+ if (pkt->isCleanEviction()) {
+ // The CleanEvict and WritebackClean snoops into other
+ // peer caches of the same level while traversing the
+ // crossbar. If a copy of the block is found, the
+ // packet is deleted in the crossbar. Hence, none of
+ // the other upper level caches connected to this
+ // cache have the block, so we can clear the
+ // BLOCK_CACHED flag in the Writeback if set and
+ // discard the CleanEvict by returning true.
+ wbPkt->clearBlockCached();
+ return true;
+ } else {
+ assert(pkt->cmd == MemCmd::WritebackDirty);
+ // Dirty writeback from above trumps our clean
+ // writeback... discard here
+ // Note: markInService will remove entry from writeback buffer.
+ markInService(wb_entry, false);
+ delete wbPkt;
+ }
+ }
+ }
+
+ // Writeback handling is special case. We can write the block into
+ // the cache without having a writeable copy (or any copy at all).
+ if (pkt->isWriteback()) {
+ assert(blkSize == pkt->getSize());
+
+ // we could get a clean writeback while we are having
+ // outstanding accesses to a block, do the simple thing for
+ // now and drop the clean writeback so that we do not upset
+ // any ordering/decisions about ownership already taken
+ if (pkt->cmd == MemCmd::WritebackClean &&
+ mshrQueue.findMatch(pkt->getAddr(), pkt->isSecure())) {
+ DPRINTF(Cache, "Clean writeback %#llx to block with MSHR, "
+ "dropping\n", pkt->getAddr());
+ return true;
+ }
+
+ if (blk == NULL) {
+ // need to do a replacement
+ blk = allocateBlock(pkt->getAddr(), pkt->isSecure(), writebacks);
+ if (blk == NULL) {
+ // no replaceable block available: give up, fwd to next level.
+ incMissCount(pkt);
+ return false;
+ }
+ tags->insertBlock(pkt, blk);
+
+ blk->status = (BlkValid | BlkReadable);
+ if (pkt->isSecure()) {
+ blk->status |= BlkSecure;
+ }
+ }
+ // only mark the block dirty if we got a writeback command,
+ // and leave it as is for a clean writeback
+ if (pkt->cmd == MemCmd::WritebackDirty) {
+ blk->status |= BlkDirty;
+ }
+ // if the packet does not have sharers, it is passing
+ // writable, and we got the writeback in Modified or Exclusive
+ // state, if not we are in the Owned or Shared state
+ if (!pkt->hasSharers()) {
+ blk->status |= BlkWritable;
+ }
+ // nothing else to do; writeback doesn't expect response
+ assert(!pkt->needsResponse());
+ std::memcpy(blk->data, pkt->getConstPtr<uint8_t>(), blkSize);
+ DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
+ incHitCount(pkt);
+ return true;
+ } else if (pkt->cmd == MemCmd::CleanEvict) {
+ if (blk != NULL) {
+ // Found the block in the tags, need to stop CleanEvict from
+ // propagating further down the hierarchy. Returning true will
+ // treat the CleanEvict like a satisfied write request and delete
+ // it.
+ return true;
+ }
+ // We didn't find the block here, propagate the CleanEvict further
+ // down the memory hierarchy. Returning false will treat the CleanEvict
+ // like a Writeback which could not find a replaceable block so has to
+ // go to next level.
+ return false;
+ } else if ((blk != NULL) &&
+ (pkt->needsWritable() ? blk->isWritable() : blk->isReadable())) {
+ // OK to satisfy access
+ incHitCount(pkt);
+ satisfyCpuSideRequest(pkt, blk);
+ return true;
+ }
+
+ // Can't satisfy access normally... either no block (blk == NULL)
+ // or have block but need writable
+
+ incMissCount(pkt);
+
+ if (blk == NULL && pkt->isLLSC() && pkt->isWrite()) {
+ // complete miss on store conditional... just give up now
+ pkt->req->setExtraData(0);
+ return true;
+ }
+
+ return false;
+}
+
+void
+Cache::doWritebacks(PacketList& writebacks, Tick forward_time)
+{
+ while (!writebacks.empty()) {
+ PacketPtr wbPkt = writebacks.front();
+ // We use forwardLatency here because we are copying writebacks to
+ // write buffer. Call isCachedAbove for both Writebacks and
+ // CleanEvicts. If isCachedAbove returns true we set BLOCK_CACHED flag
+ // in Writebacks and discard CleanEvicts.
+ if (isCachedAbove(wbPkt)) {
+ if (wbPkt->cmd == MemCmd::CleanEvict) {
+ // Delete CleanEvict because cached copies exist above. The
+ // packet destructor will delete the request object because
+ // this is a non-snoop request packet which does not require a
+ // response.
+ delete wbPkt;
+ } else if (wbPkt->cmd == MemCmd::WritebackClean) {
+ // clean writeback, do not send since the block is
+ // still cached above
+ assert(writebackClean);
+ delete wbPkt;
+ } else {
+ assert(wbPkt->cmd == MemCmd::WritebackDirty);
+ // Set BLOCK_CACHED flag in Writeback and send below, so that
+ // the Writeback does not reset the bit corresponding to this
+ // address in the snoop filter below.
+ wbPkt->setBlockCached();
+ allocateWriteBuffer(wbPkt, forward_time);
+ }
+ } else {
+ // If the block is not cached above, send packet below. Both
+ // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
+ // reset the bit corresponding to this address in the snoop filter
+ // below.
+ allocateWriteBuffer(wbPkt, forward_time);
+ }
+ writebacks.pop_front();
+ }
+}
+
+void
+Cache::doWritebacksAtomic(PacketList& writebacks)
+{
+ while (!writebacks.empty()) {
+ PacketPtr wbPkt = writebacks.front();
+ // Call isCachedAbove for both Writebacks and CleanEvicts. If
+ // isCachedAbove returns true we set BLOCK_CACHED flag in Writebacks
+ // and discard CleanEvicts.
+ if (isCachedAbove(wbPkt, false)) {
+ if (wbPkt->cmd == MemCmd::WritebackDirty) {
+ // Set BLOCK_CACHED flag in Writeback and send below,
+ // so that the Writeback does not reset the bit
+ // corresponding to this address in the snoop filter
+ // below. We can discard CleanEvicts because cached
+ // copies exist above. Atomic mode isCachedAbove
+ // modifies packet to set BLOCK_CACHED flag
+ memSidePort->sendAtomic(wbPkt);
+ }
+ } else {
+ // If the block is not cached above, send packet below. Both
+ // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
+ // reset the bit corresponding to this address in the snoop filter
+ // below.
+ memSidePort->sendAtomic(wbPkt);
+ }
+ writebacks.pop_front();
+ // In case of CleanEvicts, the packet destructor will delete the
+ // request object because this is a non-snoop request packet which
+ // does not require a response.
+ delete wbPkt;
+ }
+}
+
+
+void
+Cache::recvTimingSnoopResp(PacketPtr pkt)
+{
+ DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
+ pkt->cmdString(), pkt->getAddr(), pkt->getSize());
+
+ assert(pkt->isResponse());
+ assert(!system->bypassCaches());
+
+ // determine if the response is from a snoop request we created
+ // (in which case it should be in the outstandingSnoop), or if we
+ // merely forwarded someone else's snoop request
+ const bool forwardAsSnoop = outstandingSnoop.find(pkt->req) ==
+ outstandingSnoop.end();
+
+ if (!forwardAsSnoop) {
+ // the packet came from this cache, so sink it here and do not
+ // forward it
+ assert(pkt->cmd == MemCmd::HardPFResp);
+
+ outstandingSnoop.erase(pkt->req);
+
+ DPRINTF(Cache, "Got prefetch response from above for addr "
+ "%#llx (%s)\n", pkt->getAddr(), pkt->isSecure() ? "s" : "ns");
+ recvTimingResp(pkt);
+ return;
+ }
+
+ // forwardLatency is set here because there is a response from an
+ // upper level cache.
+ // To pay the delay that occurs if the packet comes from the bus,
+ // we charge also headerDelay.
+ Tick snoop_resp_time = clockEdge(forwardLatency) + pkt->headerDelay;
+ // Reset the timing of the packet.
+ pkt->headerDelay = pkt->payloadDelay = 0;
+ memSidePort->schedTimingSnoopResp(pkt, snoop_resp_time);
+}
+
+void
+Cache::promoteWholeLineWrites(PacketPtr pkt)
+{
+ // Cache line clearing instructions
+ if (doFastWrites && (pkt->cmd == MemCmd::WriteReq) &&
+ (pkt->getSize() == blkSize) && (pkt->getOffset(blkSize) == 0)) {
+ pkt->cmd = MemCmd::WriteLineReq;
+ DPRINTF(Cache, "packet promoted from Write to WriteLineReq\n");
+ }
+}
+
+bool
+Cache::recvTimingReq(PacketPtr pkt)
+{
+ DPRINTF(CacheTags, "%s tags: %s\n", __func__, tags->print());
+
+ assert(pkt->isRequest());
+
+ // Just forward the packet if caches are disabled.
+ if (system->bypassCaches()) {
+ // @todo This should really enqueue the packet rather
+ bool M5_VAR_USED success = memSidePort->sendTimingReq(pkt);
+ assert(success);
+ return true;
+ }
+
+ promoteWholeLineWrites(pkt);
+
+ if (pkt->cacheResponding()) {
+ // a cache above us (but not where the packet came from) is
+ // responding to the request, in other words it has the line
+ // in Modified or Owned state
+ DPRINTF(Cache, "Cache above responding to %#llx (%s): "
+ "not responding\n",
+ pkt->getAddr(), pkt->isSecure() ? "s" : "ns");
+
+ // if the packet needs the block to be writable, and the cache
+ // that has promised to respond (setting the cache responding
+ // flag) is not providing writable (it is in Owned rather than
+ // the Modified state), we know that there may be other Shared
+ // copies in the system; go out and invalidate them all
+ if (pkt->needsWritable() && !pkt->responderHadWritable()) {
+ // an upstream cache that had the line in Owned state
+ // (dirty, but not writable), is responding and thus
+ // transferring the dirty line from one branch of the
+ // cache hierarchy to another
+
+ // send out an express snoop and invalidate all other
+ // copies (snooping a packet that needs writable is the
+ // same as an invalidation), thus turning the Owned line
+ // into a Modified line, note that we don't invalidate the
+ // block in the current cache or any other cache on the
+ // path to memory
+
+ // create a downstream express snoop with cleared packet
+ // flags, there is no need to allocate any data as the
+ // packet is merely used to co-ordinate state transitions
+ Packet *snoop_pkt = new Packet(pkt, true, false);
+
+ // also reset the bus time that the original packet has
+ // not yet paid for
+ snoop_pkt->headerDelay = snoop_pkt->payloadDelay = 0;
+
+ // make this an instantaneous express snoop, and let the
+ // other caches in the system know that the another cache
+ // is responding, because we have found the authorative
+ // copy (Modified or Owned) that will supply the right
+ // data
+ snoop_pkt->setExpressSnoop();
+ snoop_pkt->setCacheResponding();
+
+ // this express snoop travels towards the memory, and at
+ // every crossbar it is snooped upwards thus reaching
+ // every cache in the system
+ bool M5_VAR_USED success = memSidePort->sendTimingReq(snoop_pkt);
+ // express snoops always succeed
+ assert(success);
+
+ // main memory will delete the snoop packet
+ }
+
+ // queue for deletion, as opposed to immediate deletion, as
+ // the sending cache is still relying on the packet
+ pendingDelete.reset(pkt);
+
+ // no need to take any action in this particular cache as an
+ // upstream cache has already committed to responding, and
+ // either the packet does not need writable (and we can let
+ // the cache that set the cache responding flag pass on the
+ // line without any need for intervention), or if the packet
+ // needs writable it is provided, or we have already sent out
+ // any express snoops in the section above
+ return true;
+ }
+
+ // anything that is merely forwarded pays for the forward latency and
+ // the delay provided by the crossbar
+ Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
+
+ // We use lookupLatency here because it is used to specify the latency
+ // to access.
+ Cycles lat = lookupLatency;
+ CacheBlk *blk = NULL;
+ bool satisfied = false;
+ {
+ PacketList writebacks;
+ // Note that lat is passed by reference here. The function
+ // access() calls accessBlock() which can modify lat value.
+ satisfied = access(pkt, blk, lat, writebacks);
+
+ // copy writebacks to write buffer here to ensure they logically
+ // proceed anything happening below
+ doWritebacks(writebacks, forward_time);
+ }
+
+ // Here we charge the headerDelay that takes into account the latencies
+ // of the bus, if the packet comes from it.
+ // The latency charged it is just lat that is the value of lookupLatency
+ // modified by access() function, or if not just lookupLatency.
+ // In case of a hit we are neglecting response latency.
+ // In case of a miss we are neglecting forward latency.
+ Tick request_time = clockEdge(lat) + pkt->headerDelay;
+ // Here we reset the timing of the packet.
+ pkt->headerDelay = pkt->payloadDelay = 0;
+
+ // track time of availability of next prefetch, if any
+ Tick next_pf_time = MaxTick;
+
+ bool needsResponse = pkt->needsResponse();
+
+ if (satisfied) {
+ // should never be satisfying an uncacheable access as we
+ // flush and invalidate any existing block as part of the
+ // lookup
+ assert(!pkt->req->isUncacheable());
+
+ // hit (for all other request types)
+
+ if (prefetcher && (prefetchOnAccess || (blk && blk->wasPrefetched()))) {
+ if (blk)
+ blk->status &= ~BlkHWPrefetched;
+
+ // Don't notify on SWPrefetch
+ if (!pkt->cmd.isSWPrefetch())
+ next_pf_time = prefetcher->notify(pkt);
+ }
+
+ if (needsResponse) {
+ pkt->makeTimingResponse();
+ // @todo: Make someone pay for this
+ pkt->headerDelay = pkt->payloadDelay = 0;
+
+ // In this case we are considering request_time that takes
+ // into account the delay of the xbar, if any, and just
+ // lat, neglecting responseLatency, modelling hit latency
+ // just as lookupLatency or or the value of lat overriden
+ // by access(), that calls accessBlock() function.
+ cpuSidePort->schedTimingResp(pkt, request_time, true);
+ } else {
+ DPRINTF(Cache, "%s satisfied %s addr %#llx, no response needed\n",
+ __func__, pkt->cmdString(), pkt->getAddr(),
+ pkt->getSize());
+
+ // queue the packet for deletion, as the sending cache is
+ // still relying on it; if the block is found in access(),
+ // CleanEvict and Writeback messages will be deleted
+ // here as well
+ pendingDelete.reset(pkt);
+ }
+ } else {
+ // miss
+
+ Addr blk_addr = blockAlign(pkt->getAddr());
+
+ // ignore any existing MSHR if we are dealing with an
+ // uncacheable request
+ MSHR *mshr = pkt->req->isUncacheable() ? nullptr :
+ mshrQueue.findMatch(blk_addr, pkt->isSecure());
+
+ // Software prefetch handling:
+ // To keep the core from waiting on data it won't look at
+ // anyway, send back a response with dummy data. Miss handling
+ // will continue asynchronously. Unfortunately, the core will
+ // insist upon freeing original Packet/Request, so we have to
+ // create a new pair with a different lifecycle. Note that this
+ // processing happens before any MSHR munging on the behalf of
+ // this request because this new Request will be the one stored
+ // into the MSHRs, not the original.
+ if (pkt->cmd.isSWPrefetch()) {
+ assert(needsResponse);
+ assert(pkt->req->hasPaddr());
+ assert(!pkt->req->isUncacheable());
-#if defined(USE_CACHE_SPLIT)
-template class Cache<Split>;
+ // There's no reason to add a prefetch as an additional target
+ // to an existing MSHR. If an outstanding request is already
+ // in progress, there is nothing for the prefetch to do.
+ // If this is the case, we don't even create a request at all.
+ PacketPtr pf = nullptr;
+
+ if (!mshr) {
+ // copy the request and create a new SoftPFReq packet
+ RequestPtr req = new Request(pkt->req->getPaddr(),
+ pkt->req->getSize(),
+ pkt->req->getFlags(),
+ pkt->req->masterId());
+ pf = new Packet(req, pkt->cmd);
+ pf->allocate();
+ assert(pf->getAddr() == pkt->getAddr());
+ assert(pf->getSize() == pkt->getSize());
+ }
+
+ pkt->makeTimingResponse();
+
+ // request_time is used here, taking into account lat and the delay
+ // charged if the packet comes from the xbar.
+ cpuSidePort->schedTimingResp(pkt, request_time, true);
+
+ // If an outstanding request is in progress (we found an
+ // MSHR) this is set to null
+ pkt = pf;
+ }
+
+ if (mshr) {
+ /// MSHR hit
+ /// @note writebacks will be checked in getNextMSHR()
+ /// for any conflicting requests to the same block
+
+ //@todo remove hw_pf here
+
+ // Coalesce unless it was a software prefetch (see above).
+ if (pkt) {
+ assert(!pkt->isWriteback());
+ // CleanEvicts corresponding to blocks which have
+ // outstanding requests in MSHRs are simply sunk here
+ if (pkt->cmd == MemCmd::CleanEvict) {
+ pendingDelete.reset(pkt);
+ } else {
+ DPRINTF(Cache, "%s coalescing MSHR for %s addr %#llx size %d\n",
+ __func__, pkt->cmdString(), pkt->getAddr(),
+ pkt->getSize());
+
+ assert(pkt->req->masterId() < system->maxMasters());
+ mshr_hits[pkt->cmdToIndex()][pkt->req->masterId()]++;
+ // We use forward_time here because it is the same
+ // considering new targets. We have multiple
+ // requests for the same address here. It
+ // specifies the latency to allocate an internal
+ // buffer and to schedule an event to the queued
+ // port and also takes into account the additional
+ // delay of the xbar.
+ mshr->allocateTarget(pkt, forward_time, order++,
+ allocOnFill(pkt->cmd));
+ if (mshr->getNumTargets() == numTarget) {
+ noTargetMSHR = mshr;
+ setBlocked(Blocked_NoTargets);
+ // need to be careful with this... if this mshr isn't
+ // ready yet (i.e. time > curTick()), we don't want to
+ // move it ahead of mshrs that are ready
+ // mshrQueue.moveToFront(mshr);
+ }
+ }
+ // We should call the prefetcher reguardless if the request is
+ // satisfied or not, reguardless if the request is in the MSHR or
+ // not. The request could be a ReadReq hit, but still not
+ // satisfied (potentially because of a prior write to the same
+ // cache line. So, even when not satisfied, tehre is an MSHR
+ // already allocated for this, we need to let the prefetcher know
+ // about the request
+ if (prefetcher) {
+ // Don't notify on SWPrefetch
+ if (!pkt->cmd.isSWPrefetch())
+ next_pf_time = prefetcher->notify(pkt);
+ }
+ }
+ } else {
+ // no MSHR
+ assert(pkt->req->masterId() < system->maxMasters());
+ if (pkt->req->isUncacheable()) {
+ mshr_uncacheable[pkt->cmdToIndex()][pkt->req->masterId()]++;
+ } else {
+ mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
+ }
+
+ if (pkt->isEviction() ||
+ (pkt->req->isUncacheable() && pkt->isWrite())) {
+ // We use forward_time here because there is an
+ // uncached memory write, forwarded to WriteBuffer.
+ allocateWriteBuffer(pkt, forward_time);
+ } else {
+ if (blk && blk->isValid()) {
+ // should have flushed and have no valid block
+ assert(!pkt->req->isUncacheable());
+
+ // If we have a write miss to a valid block, we
+ // need to mark the block non-readable. Otherwise
+ // if we allow reads while there's an outstanding
+ // write miss, the read could return stale data
+ // out of the cache block... a more aggressive
+ // system could detect the overlap (if any) and
+ // forward data out of the MSHRs, but we don't do
+ // that yet. Note that we do need to leave the
+ // block valid so that it stays in the cache, in
+ // case we get an upgrade response (and hence no
+ // new data) when the write miss completes.
+ // As long as CPUs do proper store/load forwarding
+ // internally, and have a sufficiently weak memory
+ // model, this is probably unnecessary, but at some
+ // point it must have seemed like we needed it...
+ assert(pkt->needsWritable());
+ assert(!blk->isWritable());
+ blk->status &= ~BlkReadable;
+ }
+ // Here we are using forward_time, modelling the latency of
+ // a miss (outbound) just as forwardLatency, neglecting the
+ // lookupLatency component.
+ allocateMissBuffer(pkt, forward_time);
+ }
+
+ if (prefetcher) {
+ // Don't notify on SWPrefetch
+ if (!pkt->cmd.isSWPrefetch())
+ next_pf_time = prefetcher->notify(pkt);
+ }
+ }
+ }
+
+ if (next_pf_time != MaxTick)
+ schedMemSideSendEvent(next_pf_time);
+
+ return true;
+}
+
+
+// See comment in cache.hh.
+PacketPtr
+Cache::getBusPacket(PacketPtr cpu_pkt, CacheBlk *blk,
+ bool needsWritable) const
+{
+ bool blkValid = blk && blk->isValid();
+
+ if (cpu_pkt->req->isUncacheable()) {
+ // note that at the point we see the uncacheable request we
+ // flush any block, but there could be an outstanding MSHR,
+ // and the cache could have filled again before we actually
+ // send out the forwarded uncacheable request (blk could thus
+ // be non-null)
+ return NULL;
+ }
+
+ if (!blkValid &&
+ (cpu_pkt->isUpgrade() ||
+ cpu_pkt->isEviction())) {
+ // Writebacks that weren't allocated in access() and upgrades
+ // from upper-level caches that missed completely just go
+ // through.
+ return NULL;
+ }
+
+ assert(cpu_pkt->needsResponse());
+
+ MemCmd cmd;
+ // @TODO make useUpgrades a parameter.
+ // Note that ownership protocols require upgrade, otherwise a
+ // write miss on a shared owned block will generate a ReadExcl,
+ // which will clobber the owned copy.
+ const bool useUpgrades = true;
+ if (blkValid && useUpgrades) {
+ // only reason to be here is that blk is read only and we need
+ // it to be writable
+ assert(needsWritable);
+ assert(!blk->isWritable());
+ cmd = cpu_pkt->isLLSC() ? MemCmd::SCUpgradeReq : MemCmd::UpgradeReq;
+ } else if (cpu_pkt->cmd == MemCmd::SCUpgradeFailReq ||
+ cpu_pkt->cmd == MemCmd::StoreCondFailReq) {
+ // Even though this SC will fail, we still need to send out the
+ // request and get the data to supply it to other snoopers in the case
+ // where the determination the StoreCond fails is delayed due to
+ // all caches not being on the same local bus.
+ cmd = MemCmd::SCUpgradeFailReq;
+ } else if (cpu_pkt->cmd == MemCmd::WriteLineReq) {
+ // forward as invalidate to all other caches, this gives us
+ // the line in Exclusive state, and invalidates all other
+ // copies
+ cmd = MemCmd::InvalidateReq;
+ } else {
+ // block is invalid
+ cmd = needsWritable ? MemCmd::ReadExReq :
+ (isReadOnly ? MemCmd::ReadCleanReq : MemCmd::ReadSharedReq);
+ }
+ PacketPtr pkt = new Packet(cpu_pkt->req, cmd, blkSize);
+
+ // if there are upstream caches that have already marked the
+ // packet as having sharers (not passing writable), pass that info
+ // downstream
+ if (cpu_pkt->hasSharers()) {
+ // note that cpu_pkt may have spent a considerable time in the
+ // MSHR queue and that the information could possibly be out
+ // of date, however, there is no harm in conservatively
+ // assuming the block has sharers
+ pkt->setHasSharers();
+ DPRINTF(Cache, "%s passing hasSharers from %s to %s addr %#llx "
+ "size %d\n",
+ __func__, cpu_pkt->cmdString(), pkt->cmdString(),
+ pkt->getAddr(), pkt->getSize());
+ }
+
+ // the packet should be block aligned
+ assert(pkt->getAddr() == blockAlign(pkt->getAddr()));
+
+ pkt->allocate();
+ DPRINTF(Cache, "%s created %s from %s for addr %#llx size %d\n",
+ __func__, pkt->cmdString(), cpu_pkt->cmdString(), pkt->getAddr(),
+ pkt->getSize());
+ return pkt;
+}
+
+
+Tick
+Cache::recvAtomic(PacketPtr pkt)
+{
+ // We are in atomic mode so we pay just for lookupLatency here.
+ Cycles lat = lookupLatency;
+
+ // Forward the request if the system is in cache bypass mode.
+ if (system->bypassCaches())
+ return ticksToCycles(memSidePort->sendAtomic(pkt));
+
+ promoteWholeLineWrites(pkt);
+
+ // follow the same flow as in recvTimingReq, and check if a cache
+ // above us is responding
+ if (pkt->cacheResponding()) {
+ DPRINTF(Cache, "Cache above responding to %#llx (%s): "
+ "not responding\n",
+ pkt->getAddr(), pkt->isSecure() ? "s" : "ns");
+
+ // if a cache is responding, and it had the line in Owned
+ // rather than Modified state, we need to invalidate any
+ // copies that are not on the same path to memory
+ if (pkt->needsWritable() && !pkt->responderHadWritable()) {
+ lat += ticksToCycles(memSidePort->sendAtomic(pkt));
+ }
+
+ return lat * clockPeriod();
+ }
+
+ // should assert here that there are no outstanding MSHRs or
+ // writebacks... that would mean that someone used an atomic
+ // access in timing mode
+
+ CacheBlk *blk = NULL;
+ PacketList writebacks;
+ bool satisfied = access(pkt, blk, lat, writebacks);
+
+ // handle writebacks resulting from the access here to ensure they
+ // logically proceed anything happening below
+ doWritebacksAtomic(writebacks);
+
+ if (!satisfied) {
+ // MISS
+
+ PacketPtr bus_pkt = getBusPacket(pkt, blk, pkt->needsWritable());
+
+ bool is_forward = (bus_pkt == NULL);
+
+ if (is_forward) {
+ // just forwarding the same request to the next level
+ // no local cache operation involved
+ bus_pkt = pkt;
+ }
+
+ DPRINTF(Cache, "Sending an atomic %s for %#llx (%s)\n",
+ bus_pkt->cmdString(), bus_pkt->getAddr(),
+ bus_pkt->isSecure() ? "s" : "ns");
+
+#if TRACING_ON
+ CacheBlk::State old_state = blk ? blk->status : 0;
#endif
-#if defined(USE_CACHE_SPLIT_LIFO)
-template class Cache<SplitLIFO>;
+ lat += ticksToCycles(memSidePort->sendAtomic(bus_pkt));
+
+ // We are now dealing with the response handling
+ DPRINTF(Cache, "Receive response: %s for addr %#llx (%s) in state %i\n",
+ bus_pkt->cmdString(), bus_pkt->getAddr(),
+ bus_pkt->isSecure() ? "s" : "ns",
+ old_state);
+
+ // If packet was a forward, the response (if any) is already
+ // in place in the bus_pkt == pkt structure, so we don't need
+ // to do anything. Otherwise, use the separate bus_pkt to
+ // generate response to pkt and then delete it.
+ if (!is_forward) {
+ if (pkt->needsResponse()) {
+ assert(bus_pkt->isResponse());
+ if (bus_pkt->isError()) {
+ pkt->makeAtomicResponse();
+ pkt->copyError(bus_pkt);
+ } else if (pkt->cmd == MemCmd::InvalidateReq) {
+ if (blk) {
+ // invalidate response to a cache that received
+ // an invalidate request
+ satisfyCpuSideRequest(pkt, blk);
+ }
+ } else if (pkt->cmd == MemCmd::WriteLineReq) {
+ // note the use of pkt, not bus_pkt here.
+
+ // write-line request to the cache that promoted
+ // the write to a whole line
+ blk = handleFill(pkt, blk, writebacks,
+ allocOnFill(pkt->cmd));
+ satisfyCpuSideRequest(pkt, blk);
+ } else if (bus_pkt->isRead() ||
+ bus_pkt->cmd == MemCmd::UpgradeResp) {
+ // we're updating cache state to allow us to
+ // satisfy the upstream request from the cache
+ blk = handleFill(bus_pkt, blk, writebacks,
+ allocOnFill(pkt->cmd));
+ satisfyCpuSideRequest(pkt, blk);
+ } else {
+ // we're satisfying the upstream request without
+ // modifying cache state, e.g., a write-through
+ pkt->makeAtomicResponse();
+ }
+ }
+ delete bus_pkt;
+ }
+ }
+
+ // Note that we don't invoke the prefetcher at all in atomic mode.
+ // It's not clear how to do it properly, particularly for
+ // prefetchers that aggressively generate prefetch candidates and
+ // rely on bandwidth contention to throttle them; these will tend
+ // to pollute the cache in atomic mode since there is no bandwidth
+ // contention. If we ever do want to enable prefetching in atomic
+ // mode, though, this is the place to do it... see timingAccess()
+ // for an example (though we'd want to issue the prefetch(es)
+ // immediately rather than calling requestMemSideBus() as we do
+ // there).
+
+ // do any writebacks resulting from the response handling
+ doWritebacksAtomic(writebacks);
+
+ // if we used temp block, check to see if its valid and if so
+ // clear it out, but only do so after the call to recvAtomic is
+ // finished so that any downstream observers (such as a snoop
+ // filter), first see the fill, and only then see the eviction
+ if (blk == tempBlock && tempBlock->isValid()) {
+ // the atomic CPU calls recvAtomic for fetch and load/store
+ // sequentuially, and we may already have a tempBlock
+ // writeback from the fetch that we have not yet sent
+ if (tempBlockWriteback) {
+ // if that is the case, write the prevoius one back, and
+ // do not schedule any new event
+ writebackTempBlockAtomic();
+ } else {
+ // the writeback/clean eviction happens after the call to
+ // recvAtomic has finished (but before any successive
+ // calls), so that the response handling from the fill is
+ // allowed to happen first
+ schedule(writebackTempBlockAtomicEvent, curTick());
+ }
+
+ tempBlockWriteback = (blk->isDirty() || writebackClean) ?
+ writebackBlk(blk) : cleanEvictBlk(blk);
+ blk->invalidate();
+ }
+
+ if (pkt->needsResponse()) {
+ pkt->makeAtomicResponse();
+ }
+
+ return lat * clockPeriod();
+}
+
+
+void
+Cache::functionalAccess(PacketPtr pkt, bool fromCpuSide)
+{
+ if (system->bypassCaches()) {
+ // Packets from the memory side are snoop request and
+ // shouldn't happen in bypass mode.
+ assert(fromCpuSide);
+
+ // The cache should be flushed if we are in cache bypass mode,
+ // so we don't need to check if we need to update anything.
+ memSidePort->sendFunctional(pkt);
+ return;
+ }
+
+ Addr blk_addr = blockAlign(pkt->getAddr());
+ bool is_secure = pkt->isSecure();
+ CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
+ MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
+
+ pkt->pushLabel(name());
+
+ CacheBlkPrintWrapper cbpw(blk);
+
+ // Note that just because an L2/L3 has valid data doesn't mean an
+ // L1 doesn't have a more up-to-date modified copy that still
+ // needs to be found. As a result we always update the request if
+ // we have it, but only declare it satisfied if we are the owner.
+
+ // see if we have data at all (owned or otherwise)
+ bool have_data = blk && blk->isValid()
+ && pkt->checkFunctional(&cbpw, blk_addr, is_secure, blkSize,
+ blk->data);
+
+ // data we have is dirty if marked as such or if we have an
+ // in-service MSHR that is pending a modified line
+ bool have_dirty =
+ have_data && (blk->isDirty() ||
+ (mshr && mshr->inService && mshr->isPendingModified()));
+
+ bool done = have_dirty
+ || cpuSidePort->checkFunctional(pkt)
+ || mshrQueue.checkFunctional(pkt, blk_addr)
+ || writeBuffer.checkFunctional(pkt, blk_addr)
+ || memSidePort->checkFunctional(pkt);
+
+ DPRINTF(CacheVerbose, "functional %s %#llx (%s) %s%s%s\n",
+ pkt->cmdString(), pkt->getAddr(), is_secure ? "s" : "ns",
+ (blk && blk->isValid()) ? "valid " : "",
+ have_data ? "data " : "", done ? "done " : "");
+
+ // We're leaving the cache, so pop cache->name() label
+ pkt->popLabel();
+
+ if (done) {
+ pkt->makeResponse();
+ } else {
+ // if it came as a request from the CPU side then make sure it
+ // continues towards the memory side
+ if (fromCpuSide) {
+ memSidePort->sendFunctional(pkt);
+ } else if (forwardSnoops && cpuSidePort->isSnooping()) {
+ // if it came from the memory side, it must be a snoop request
+ // and we should only forward it if we are forwarding snoops
+ cpuSidePort->sendFunctionalSnoop(pkt);
+ }
+ }
+}
+
+
+/////////////////////////////////////////////////////
+//
+// Response handling: responses from the memory side
+//
+/////////////////////////////////////////////////////
+
+
+void
+Cache::recvTimingResp(PacketPtr pkt)
+{
+ assert(pkt->isResponse());
+
+ // all header delay should be paid for by the crossbar, unless
+ // this is a prefetch response from above
+ panic_if(pkt->headerDelay != 0 && pkt->cmd != MemCmd::HardPFResp,
+ "%s saw a non-zero packet delay\n", name());
+
+ MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
+ bool is_error = pkt->isError();
+
+ assert(mshr);
+
+ if (is_error) {
+ DPRINTF(Cache, "Cache received packet with error for addr %#llx (%s), "
+ "cmd: %s\n", pkt->getAddr(), pkt->isSecure() ? "s" : "ns",
+ pkt->cmdString());
+ }
+
+ DPRINTF(Cache, "Handling response %s for addr %#llx size %d (%s)\n",
+ pkt->cmdString(), pkt->getAddr(), pkt->getSize(),
+ pkt->isSecure() ? "s" : "ns");
+
+ MSHRQueue *mq = mshr->queue;
+ bool wasFull = mq->isFull();
+
+ if (mshr == noTargetMSHR) {
+ // we always clear at least one target
+ clearBlocked(Blocked_NoTargets);
+ noTargetMSHR = NULL;
+ }
+
+ // Initial target is used just for stats
+ MSHR::Target *initial_tgt = mshr->getTarget();
+ int stats_cmd_idx = initial_tgt->pkt->cmdToIndex();
+ Tick miss_latency = curTick() - initial_tgt->recvTime;
+ PacketList writebacks;
+ // We need forward_time here because we have a call of
+ // allocateWriteBuffer() that need this parameter to specify the
+ // time to request the bus. In this case we use forward latency
+ // because there is a writeback. We pay also here for headerDelay
+ // that is charged of bus latencies if the packet comes from the
+ // bus.
+ Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
+
+ if (pkt->req->isUncacheable()) {
+ assert(pkt->req->masterId() < system->maxMasters());
+ mshr_uncacheable_lat[stats_cmd_idx][pkt->req->masterId()] +=
+ miss_latency;
+ } else {
+ assert(pkt->req->masterId() < system->maxMasters());
+ mshr_miss_latency[stats_cmd_idx][pkt->req->masterId()] +=
+ miss_latency;
+ }
+
+ // upgrade deferred targets if the response has no sharers, and is
+ // thus passing writable
+ if (!pkt->hasSharers()) {
+ mshr->promoteWritable();
+ }
+
+ bool is_fill = !mshr->isForward &&
+ (pkt->isRead() || pkt->cmd == MemCmd::UpgradeResp);
+
+ CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
+
+ if (is_fill && !is_error) {
+ DPRINTF(Cache, "Block for addr %#llx being updated in Cache\n",
+ pkt->getAddr());
+
+ blk = handleFill(pkt, blk, writebacks, mshr->allocOnFill);
+ assert(blk != NULL);
+ }
+
+ // allow invalidation responses originating from write-line
+ // requests to be discarded
+ bool is_invalidate = pkt->isInvalidate();
+
+ // First offset for critical word first calculations
+ int initial_offset = initial_tgt->pkt->getOffset(blkSize);
+
+ while (mshr->hasTargets()) {
+ MSHR::Target *target = mshr->getTarget();
+ Packet *tgt_pkt = target->pkt;
+
+ switch (target->source) {
+ case MSHR::Target::FromCPU:
+ Tick completion_time;
+ // Here we charge on completion_time the delay of the xbar if the
+ // packet comes from it, charged on headerDelay.
+ completion_time = pkt->headerDelay;
+
+ // Software prefetch handling for cache closest to core
+ if (tgt_pkt->cmd.isSWPrefetch()) {
+ // a software prefetch would have already been ack'd immediately
+ // with dummy data so the core would be able to retire it.
+ // this request completes right here, so we deallocate it.
+ delete tgt_pkt->req;
+ delete tgt_pkt;
+ break; // skip response
+ }
+
+ // unlike the other packet flows, where data is found in other
+ // caches or memory and brought back, write-line requests always
+ // have the data right away, so the above check for "is fill?"
+ // cannot actually be determined until examining the stored MSHR
+ // state. We "catch up" with that logic here, which is duplicated
+ // from above.
+ if (tgt_pkt->cmd == MemCmd::WriteLineReq) {
+ assert(!is_error);
+ // we got the block in a writable state, so promote
+ // any deferred targets if possible
+ mshr->promoteWritable();
+ // NB: we use the original packet here and not the response!
+ blk = handleFill(tgt_pkt, blk, writebacks, mshr->allocOnFill);
+ assert(blk != NULL);
+
+ // treat as a fill, and discard the invalidation
+ // response
+ is_fill = true;
+ is_invalidate = false;
+ }
+
+ if (is_fill) {
+ satisfyCpuSideRequest(tgt_pkt, blk,
+ true, mshr->hasPostDowngrade());
+
+ // How many bytes past the first request is this one
+ int transfer_offset =
+ tgt_pkt->getOffset(blkSize) - initial_offset;
+ if (transfer_offset < 0) {
+ transfer_offset += blkSize;
+ }
+
+ // If not critical word (offset) return payloadDelay.
+ // responseLatency is the latency of the return path
+ // from lower level caches/memory to an upper level cache or
+ // the core.
+ completion_time += clockEdge(responseLatency) +
+ (transfer_offset ? pkt->payloadDelay : 0);
+
+ assert(!tgt_pkt->req->isUncacheable());
+
+ assert(tgt_pkt->req->masterId() < system->maxMasters());
+ missLatency[tgt_pkt->cmdToIndex()][tgt_pkt->req->masterId()] +=
+ completion_time - target->recvTime;
+ } else if (pkt->cmd == MemCmd::UpgradeFailResp) {
+ // failed StoreCond upgrade
+ assert(tgt_pkt->cmd == MemCmd::StoreCondReq ||
+ tgt_pkt->cmd == MemCmd::StoreCondFailReq ||
+ tgt_pkt->cmd == MemCmd::SCUpgradeFailReq);
+ // responseLatency is the latency of the return path
+ // from lower level caches/memory to an upper level cache or
+ // the core.
+ completion_time += clockEdge(responseLatency) +
+ pkt->payloadDelay;
+ tgt_pkt->req->setExtraData(0);
+ } else {
+ // not a cache fill, just forwarding response
+ // responseLatency is the latency of the return path
+ // from lower level cahces/memory to the core.
+ completion_time += clockEdge(responseLatency) +
+ pkt->payloadDelay;
+ if (pkt->isRead() && !is_error) {
+ // sanity check
+ assert(pkt->getAddr() == tgt_pkt->getAddr());
+ assert(pkt->getSize() >= tgt_pkt->getSize());
+
+ tgt_pkt->setData(pkt->getConstPtr<uint8_t>());
+ }
+ }
+ tgt_pkt->makeTimingResponse();
+ // if this packet is an error copy that to the new packet
+ if (is_error)
+ tgt_pkt->copyError(pkt);
+ if (tgt_pkt->cmd == MemCmd::ReadResp &&
+ (is_invalidate || mshr->hasPostInvalidate())) {
+ // If intermediate cache got ReadRespWithInvalidate,
+ // propagate that. Response should not have
+ // isInvalidate() set otherwise.
+ tgt_pkt->cmd = MemCmd::ReadRespWithInvalidate;
+ DPRINTF(Cache, "%s updated cmd to %s for addr %#llx\n",
+ __func__, tgt_pkt->cmdString(), tgt_pkt->getAddr());
+ }
+ // Reset the bus additional time as it is now accounted for
+ tgt_pkt->headerDelay = tgt_pkt->payloadDelay = 0;
+ cpuSidePort->schedTimingResp(tgt_pkt, completion_time, true);
+ break;
+
+ case MSHR::Target::FromPrefetcher:
+ assert(tgt_pkt->cmd == MemCmd::HardPFReq);
+ if (blk)
+ blk->status |= BlkHWPrefetched;
+ delete tgt_pkt->req;
+ delete tgt_pkt;
+ break;
+
+ case MSHR::Target::FromSnoop:
+ // I don't believe that a snoop can be in an error state
+ assert(!is_error);
+ // response to snoop request
+ DPRINTF(Cache, "processing deferred snoop...\n");
+ assert(!(is_invalidate && !mshr->hasPostInvalidate()));
+ handleSnoop(tgt_pkt, blk, true, true, mshr->hasPostInvalidate());
+ break;
+
+ default:
+ panic("Illegal target->source enum %d\n", target->source);
+ }
+
+ mshr->popTarget();
+ }
+
+ if (blk && blk->isValid()) {
+ // an invalidate response stemming from a write line request
+ // should not invalidate the block, so check if the
+ // invalidation should be discarded
+ if (is_invalidate || mshr->hasPostInvalidate()) {
+ invalidateBlock(blk);
+ } else if (mshr->hasPostDowngrade()) {
+ blk->status &= ~BlkWritable;
+ }
+ }
+
+ if (mshr->promoteDeferredTargets()) {
+ // avoid later read getting stale data while write miss is
+ // outstanding.. see comment in timingAccess()
+ if (blk) {
+ blk->status &= ~BlkReadable;
+ }
+ mq = mshr->queue;
+ mq->markPending(mshr);
+ schedMemSideSendEvent(clockEdge() + pkt->payloadDelay);
+ } else {
+ mq->deallocate(mshr);
+ if (wasFull && !mq->isFull()) {
+ clearBlocked((BlockedCause)mq->index);
+ }
+
+ // Request the bus for a prefetch if this deallocation freed enough
+ // MSHRs for a prefetch to take place
+ if (prefetcher && mq == &mshrQueue && mshrQueue.canPrefetch()) {
+ Tick next_pf_time = std::max(prefetcher->nextPrefetchReadyTime(),
+ clockEdge());
+ if (next_pf_time != MaxTick)
+ schedMemSideSendEvent(next_pf_time);
+ }
+ }
+ // reset the xbar additional timinig as it is now accounted for
+ pkt->headerDelay = pkt->payloadDelay = 0;
+
+ // copy writebacks to write buffer
+ doWritebacks(writebacks, forward_time);
+
+ // if we used temp block, check to see if its valid and then clear it out
+ if (blk == tempBlock && tempBlock->isValid()) {
+ // We use forwardLatency here because we are copying
+ // Writebacks/CleanEvicts to write buffer. It specifies the latency to
+ // allocate an internal buffer and to schedule an event to the
+ // queued port.
+ if (blk->isDirty() || writebackClean) {
+ PacketPtr wbPkt = writebackBlk(blk);
+ allocateWriteBuffer(wbPkt, forward_time);
+ // Set BLOCK_CACHED flag if cached above.
+ if (isCachedAbove(wbPkt))
+ wbPkt->setBlockCached();
+ } else {
+ PacketPtr wcPkt = cleanEvictBlk(blk);
+ // Check to see if block is cached above. If not allocate
+ // write buffer
+ if (isCachedAbove(wcPkt))
+ delete wcPkt;
+ else
+ allocateWriteBuffer(wcPkt, forward_time);
+ }
+ blk->invalidate();
+ }
+
+ DPRINTF(CacheVerbose, "Leaving %s with %s for addr %#llx\n", __func__,
+ pkt->cmdString(), pkt->getAddr());
+ delete pkt;
+}
+
+PacketPtr
+Cache::writebackBlk(CacheBlk *blk)
+{
+ chatty_assert(!isReadOnly || writebackClean,
+ "Writeback from read-only cache");
+ assert(blk && blk->isValid() && (blk->isDirty() || writebackClean));
+
+ writebacks[Request::wbMasterId]++;
+
+ Request *req = new Request(tags->regenerateBlkAddr(blk->tag, blk->set),
+ blkSize, 0, Request::wbMasterId);
+ if (blk->isSecure())
+ req->setFlags(Request::SECURE);
+
+ req->taskId(blk->task_id);
+ blk->task_id= ContextSwitchTaskId::Unknown;
+ blk->tickInserted = curTick();
+
+ PacketPtr pkt =
+ new Packet(req, blk->isDirty() ?
+ MemCmd::WritebackDirty : MemCmd::WritebackClean);
+
+ DPRINTF(Cache, "Create Writeback %#llx writable: %d, dirty: %d\n",
+ pkt->getAddr(), blk->isWritable(), blk->isDirty());
+
+ if (blk->isWritable()) {
+ // not asserting shared means we pass the block in modified
+ // state, mark our own block non-writeable
+ blk->status &= ~BlkWritable;
+ } else {
+ // we are in the Owned state, tell the receiver
+ pkt->setHasSharers();
+ }
+
+ // make sure the block is not marked dirty
+ blk->status &= ~BlkDirty;
+
+ pkt->allocate();
+ std::memcpy(pkt->getPtr<uint8_t>(), blk->data, blkSize);
+
+ return pkt;
+}
+
+PacketPtr
+Cache::cleanEvictBlk(CacheBlk *blk)
+{
+ assert(!writebackClean);
+ assert(blk && blk->isValid() && !blk->isDirty());
+ // Creating a zero sized write, a message to the snoop filter
+ Request *req =
+ new Request(tags->regenerateBlkAddr(blk->tag, blk->set), blkSize, 0,
+ Request::wbMasterId);
+ if (blk->isSecure())
+ req->setFlags(Request::SECURE);
+
+ req->taskId(blk->task_id);
+ blk->task_id = ContextSwitchTaskId::Unknown;
+ blk->tickInserted = curTick();
+
+ PacketPtr pkt = new Packet(req, MemCmd::CleanEvict);
+ pkt->allocate();
+ DPRINTF(Cache, "%s%s %x Create CleanEvict\n", pkt->cmdString(),
+ pkt->req->isInstFetch() ? " (ifetch)" : "",
+ pkt->getAddr());
+
+ return pkt;
+}
+
+void
+Cache::memWriteback()
+{
+ CacheBlkVisitorWrapper visitor(*this, &Cache::writebackVisitor);
+ tags->forEachBlk(visitor);
+}
+
+void
+Cache::memInvalidate()
+{
+ CacheBlkVisitorWrapper visitor(*this, &Cache::invalidateVisitor);
+ tags->forEachBlk(visitor);
+}
+
+bool
+Cache::isDirty() const
+{
+ CacheBlkIsDirtyVisitor visitor;
+ tags->forEachBlk(visitor);
+
+ return visitor.isDirty();
+}
+
+bool
+Cache::writebackVisitor(CacheBlk &blk)
+{
+ if (blk.isDirty()) {
+ assert(blk.isValid());
+
+ Request request(tags->regenerateBlkAddr(blk.tag, blk.set),
+ blkSize, 0, Request::funcMasterId);
+ request.taskId(blk.task_id);
+
+ Packet packet(&request, MemCmd::WriteReq);
+ packet.dataStatic(blk.data);
+
+ memSidePort->sendFunctional(&packet);
+
+ blk.status &= ~BlkDirty;
+ }
+
+ return true;
+}
+
+bool
+Cache::invalidateVisitor(CacheBlk &blk)
+{
+
+ if (blk.isDirty())
+ warn_once("Invalidating dirty cache lines. Expect things to break.\n");
+
+ if (blk.isValid()) {
+ assert(!blk.isDirty());
+ tags->invalidate(&blk);
+ blk.invalidate();
+ }
+
+ return true;
+}
+
+CacheBlk*
+Cache::allocateBlock(Addr addr, bool is_secure, PacketList &writebacks)
+{
+ CacheBlk *blk = tags->findVictim(addr);
+
+ // It is valid to return NULL if there is no victim
+ if (!blk)
+ return nullptr;
+
+ if (blk->isValid()) {
+ Addr repl_addr = tags->regenerateBlkAddr(blk->tag, blk->set);
+ MSHR *repl_mshr = mshrQueue.findMatch(repl_addr, blk->isSecure());
+ if (repl_mshr) {
+ // must be an outstanding upgrade request
+ // on a block we're about to replace...
+ assert(!blk->isWritable() || blk->isDirty());
+ assert(repl_mshr->needsWritable());
+ // too hard to replace block with transient state
+ // allocation failed, block not inserted
+ return NULL;
+ } else {
+ DPRINTF(Cache, "replacement: replacing %#llx (%s) with %#llx (%s): %s\n",
+ repl_addr, blk->isSecure() ? "s" : "ns",
+ addr, is_secure ? "s" : "ns",
+ blk->isDirty() ? "writeback" : "clean");
+
+ // Will send up Writeback/CleanEvict snoops via isCachedAbove
+ // when pushing this writeback list into the write buffer.
+ if (blk->isDirty() || writebackClean) {
+ // Save writeback packet for handling by caller
+ writebacks.push_back(writebackBlk(blk));
+ } else {
+ writebacks.push_back(cleanEvictBlk(blk));
+ }
+ }
+ }
+
+ return blk;
+}
+
+void
+Cache::invalidateBlock(CacheBlk *blk)
+{
+ if (blk != tempBlock)
+ tags->invalidate(blk);
+ blk->invalidate();
+}
+
+// Note that the reason we return a list of writebacks rather than
+// inserting them directly in the write buffer is that this function
+// is called by both atomic and timing-mode accesses, and in atomic
+// mode we don't mess with the write buffer (we just perform the
+// writebacks atomically once the original request is complete).
+CacheBlk*
+Cache::handleFill(PacketPtr pkt, CacheBlk *blk, PacketList &writebacks,
+ bool allocate)
+{
+ assert(pkt->isResponse() || pkt->cmd == MemCmd::WriteLineReq);
+ Addr addr = pkt->getAddr();
+ bool is_secure = pkt->isSecure();
+#if TRACING_ON
+ CacheBlk::State old_state = blk ? blk->status : 0;
#endif
-#endif //DOXYGEN_SHOULD_SKIP_THIS
+ // When handling a fill, discard any CleanEvicts for the
+ // same address in write buffer.
+ Addr M5_VAR_USED blk_addr = blockAlign(pkt->getAddr());
+ std::vector<MSHR *> M5_VAR_USED wbs;
+ assert (!writeBuffer.findMatches(blk_addr, is_secure, wbs));
+
+ if (blk == NULL) {
+ // better have read new data...
+ assert(pkt->hasData());
+
+ // only read responses and write-line requests have data;
+ // note that we don't write the data here for write-line - that
+ // happens in the subsequent satisfyCpuSideRequest.
+ assert(pkt->isRead() || pkt->cmd == MemCmd::WriteLineReq);
+
+ // need to do a replacement if allocating, otherwise we stick
+ // with the temporary storage
+ blk = allocate ? allocateBlock(addr, is_secure, writebacks) : NULL;
+
+ if (blk == NULL) {
+ // No replaceable block or a mostly exclusive
+ // cache... just use temporary storage to complete the
+ // current request and then get rid of it
+ assert(!tempBlock->isValid());
+ blk = tempBlock;
+ tempBlock->set = tags->extractSet(addr);
+ tempBlock->tag = tags->extractTag(addr);
+ // @todo: set security state as well...
+ DPRINTF(Cache, "using temp block for %#llx (%s)\n", addr,
+ is_secure ? "s" : "ns");
+ } else {
+ tags->insertBlock(pkt, blk);
+ }
+
+ // we should never be overwriting a valid block
+ assert(!blk->isValid());
+ } else {
+ // existing block... probably an upgrade
+ assert(blk->tag == tags->extractTag(addr));
+ // either we're getting new data or the block should already be valid
+ assert(pkt->hasData() || blk->isValid());
+ // don't clear block status... if block is already dirty we
+ // don't want to lose that
+ }
+
+ if (is_secure)
+ blk->status |= BlkSecure;
+ blk->status |= BlkValid | BlkReadable;
+
+ // sanity check for whole-line writes, which should always be
+ // marked as writable as part of the fill, and then later marked
+ // dirty as part of satisfyCpuSideRequest
+ if (pkt->cmd == MemCmd::WriteLineReq) {
+ assert(!pkt->hasSharers());
+ // at the moment other caches do not respond to the
+ // invalidation requests corresponding to a whole-line write
+ assert(!pkt->cacheResponding());
+ }
+
+ // here we deal with setting the appropriate state of the line,
+ // and we start by looking at the hasSharers flag, and ignore the
+ // cacheResponding flag (normally signalling dirty data) if the
+ // packet has sharers, thus the line is never allocated as Owned
+ // (dirty but not writable), and always ends up being either
+ // Shared, Exclusive or Modified, see Packet::setCacheResponding
+ // for more details
+ if (!pkt->hasSharers()) {
+ // we could get a writable line from memory (rather than a
+ // cache) even in a read-only cache, note that we set this bit
+ // even for a read-only cache, possibly revisit this decision
+ blk->status |= BlkWritable;
+
+ // check if we got this via cache-to-cache transfer (i.e., from a
+ // cache that had the block in Modified or Owned state)
+ if (pkt->cacheResponding()) {
+ // we got the block in Modified state, and invalidated the
+ // owners copy
+ blk->status |= BlkDirty;
+
+ chatty_assert(!isReadOnly, "Should never see dirty snoop response "
+ "in read-only cache %s\n", name());
+ }
+ }
+
+ DPRINTF(Cache, "Block addr %#llx (%s) moving from state %x to %s\n",
+ addr, is_secure ? "s" : "ns", old_state, blk->print());
+
+ // if we got new data, copy it in (checking for a read response
+ // and a response that has data is the same in the end)
+ if (pkt->isRead()) {
+ // sanity checks
+ assert(pkt->hasData());
+ assert(pkt->getSize() == blkSize);
+
+ std::memcpy(blk->data, pkt->getConstPtr<uint8_t>(), blkSize);
+ }
+ // We pay for fillLatency here.
+ blk->whenReady = clockEdge() + fillLatency * clockPeriod() +
+ pkt->payloadDelay;
+
+ return blk;
+}
+
+
+/////////////////////////////////////////////////////
+//
+// Snoop path: requests coming in from the memory side
+//
+/////////////////////////////////////////////////////
+
+void
+Cache::doTimingSupplyResponse(PacketPtr req_pkt, const uint8_t *blk_data,
+ bool already_copied, bool pending_inval)
+{
+ // sanity check
+ assert(req_pkt->isRequest());
+ assert(req_pkt->needsResponse());
+
+ DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
+ req_pkt->cmdString(), req_pkt->getAddr(), req_pkt->getSize());
+ // timing-mode snoop responses require a new packet, unless we
+ // already made a copy...
+ PacketPtr pkt = req_pkt;
+ if (!already_copied)
+ // do not clear flags, and allocate space for data if the
+ // packet needs it (the only packets that carry data are read
+ // responses)
+ pkt = new Packet(req_pkt, false, req_pkt->isRead());
+
+ assert(req_pkt->req->isUncacheable() || req_pkt->isInvalidate() ||
+ pkt->hasSharers());
+ pkt->makeTimingResponse();
+ if (pkt->isRead()) {
+ pkt->setDataFromBlock(blk_data, blkSize);
+ }
+ if (pkt->cmd == MemCmd::ReadResp && pending_inval) {
+ // Assume we defer a response to a read from a far-away cache
+ // A, then later defer a ReadExcl from a cache B on the same
+ // bus as us. We'll assert cacheResponding in both cases, but
+ // in the latter case cacheResponding will keep the
+ // invalidation from reaching cache A. This special response
+ // tells cache A that it gets the block to satisfy its read,
+ // but must immediately invalidate it.
+ pkt->cmd = MemCmd::ReadRespWithInvalidate;
+ }
+ // Here we consider forward_time, paying for just forward latency and
+ // also charging the delay provided by the xbar.
+ // forward_time is used as send_time in next allocateWriteBuffer().
+ Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
+ // Here we reset the timing of the packet.
+ pkt->headerDelay = pkt->payloadDelay = 0;
+ DPRINTF(CacheVerbose,
+ "%s created response: %s addr %#llx size %d tick: %lu\n",
+ __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize(),
+ forward_time);
+ memSidePort->schedTimingSnoopResp(pkt, forward_time, true);
+}
+
+uint32_t
+Cache::handleSnoop(PacketPtr pkt, CacheBlk *blk, bool is_timing,
+ bool is_deferred, bool pending_inval)
+{
+ DPRINTF(CacheVerbose, "%s for %s addr %#llx size %d\n", __func__,
+ pkt->cmdString(), pkt->getAddr(), pkt->getSize());
+ // deferred snoops can only happen in timing mode
+ assert(!(is_deferred && !is_timing));
+ // pending_inval only makes sense on deferred snoops
+ assert(!(pending_inval && !is_deferred));
+ assert(pkt->isRequest());
+
+ // the packet may get modified if we or a forwarded snooper
+ // responds in atomic mode, so remember a few things about the
+ // original packet up front
+ bool invalidate = pkt->isInvalidate();
+ bool M5_VAR_USED needs_writable = pkt->needsWritable();
+
+ // at the moment we could get an uncacheable write which does not
+ // have the invalidate flag, and we need a suitable way of dealing
+ // with this case
+ panic_if(invalidate && pkt->req->isUncacheable(),
+ "%s got an invalidating uncacheable snoop request %s to %#llx",
+ name(), pkt->cmdString(), pkt->getAddr());
+
+ uint32_t snoop_delay = 0;
+
+ if (forwardSnoops) {
+ // first propagate snoop upward to see if anyone above us wants to
+ // handle it. save & restore packet src since it will get
+ // rewritten to be relative to cpu-side bus (if any)
+ bool alreadyResponded = pkt->cacheResponding();
+ if (is_timing) {
+ // copy the packet so that we can clear any flags before
+ // forwarding it upwards, we also allocate data (passing
+ // the pointer along in case of static data), in case
+ // there is a snoop hit in upper levels
+ Packet snoopPkt(pkt, true, true);
+ snoopPkt.setExpressSnoop();
+ // the snoop packet does not need to wait any additional
+ // time
+ snoopPkt.headerDelay = snoopPkt.payloadDelay = 0;
+ cpuSidePort->sendTimingSnoopReq(&snoopPkt);
+
+ // add the header delay (including crossbar and snoop
+ // delays) of the upward snoop to the snoop delay for this
+ // cache
+ snoop_delay += snoopPkt.headerDelay;
+
+ if (snoopPkt.cacheResponding()) {
+ // cache-to-cache response from some upper cache
+ assert(!alreadyResponded);
+ pkt->setCacheResponding();
+ }
+ // upstream cache has the block, or has an outstanding
+ // MSHR, pass the flag on
+ if (snoopPkt.hasSharers()) {
+ pkt->setHasSharers();
+ }
+ // If this request is a prefetch or clean evict and an upper level
+ // signals block present, make sure to propagate the block
+ // presence to the requester.
+ if (snoopPkt.isBlockCached()) {
+ pkt->setBlockCached();
+ }
+ } else {
+ cpuSidePort->sendAtomicSnoop(pkt);
+ if (!alreadyResponded && pkt->cacheResponding()) {
+ // cache-to-cache response from some upper cache:
+ // forward response to original requester
+ assert(pkt->isResponse());
+ }
+ }
+ }
+
+ if (!blk || !blk->isValid()) {
+ DPRINTF(CacheVerbose, "%s snoop miss for %s addr %#llx size %d\n",
+ __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize());
+ return snoop_delay;
+ } else {
+ DPRINTF(Cache, "%s snoop hit for %s addr %#llx size %d, "
+ "old state is %s\n", __func__, pkt->cmdString(),
+ pkt->getAddr(), pkt->getSize(), blk->print());
+ }
+
+ chatty_assert(!(isReadOnly && blk->isDirty()),
+ "Should never have a dirty block in a read-only cache %s\n",
+ name());
+
+ // We may end up modifying both the block state and the packet (if
+ // we respond in atomic mode), so just figure out what to do now
+ // and then do it later. If we find dirty data while snooping for
+ // an invalidate, we don't need to send a response. The
+ // invalidation itself is taken care of below.
+ bool respond = blk->isDirty() && pkt->needsResponse() &&
+ pkt->cmd != MemCmd::InvalidateReq;
+ bool have_writable = blk->isWritable();
+
+ // Invalidate any prefetch's from below that would strip write permissions
+ // MemCmd::HardPFReq is only observed by upstream caches. After missing
+ // above and in it's own cache, a new MemCmd::ReadReq is created that
+ // downstream caches observe.
+ if (pkt->mustCheckAbove()) {
+ DPRINTF(Cache, "Found addr %#llx in upper level cache for snoop %s from"
+ " lower cache\n", pkt->getAddr(), pkt->cmdString());
+ pkt->setBlockCached();
+ return snoop_delay;
+ }
+
+ if (pkt->isRead() && !invalidate) {
+ // reading without requiring the line in a writable state
+ assert(!needs_writable);
+ pkt->setHasSharers();
+
+ // if the requesting packet is uncacheable, retain the line in
+ // the current state, otherwhise unset the writable flag,
+ // which means we go from Modified to Owned (and will respond
+ // below), remain in Owned (and will respond below), from
+ // Exclusive to Shared, or remain in Shared
+ if (!pkt->req->isUncacheable())
+ blk->status &= ~BlkWritable;
+ }
+
+ if (respond) {
+ // prevent anyone else from responding, cache as well as
+ // memory, and also prevent any memory from even seeing the
+ // request
+ pkt->setCacheResponding();
+ if (have_writable) {
+ // inform the cache hierarchy that this cache had the line
+ // in the Modified state so that we avoid unnecessary
+ // invalidations (see Packet::setResponderHadWritable)
+ pkt->setResponderHadWritable();
+
+ // in the case of an uncacheable request there is no point
+ // in setting the responderHadWritable flag, but since the
+ // recipient does not care there is no harm in doing so
+ } else {
+ // if the packet has needsWritable set we invalidate our
+ // copy below and all other copies will be invalidates
+ // through express snoops, and if needsWritable is not set
+ // we already called setHasSharers above
+ }
+
+ // if we are returning a writable and dirty (Modified) line,
+ // we should be invalidating the line
+ panic_if(!invalidate && !pkt->hasSharers(),
+ "%s is passing a Modified line through %s to %#llx, "
+ "but keeping the block",
+ name(), pkt->cmdString(), pkt->getAddr());
+
+ if (is_timing) {
+ doTimingSupplyResponse(pkt, blk->data, is_deferred, pending_inval);
+ } else {
+ pkt->makeAtomicResponse();
+ // packets such as upgrades do not actually have any data
+ // payload
+ if (pkt->hasData())
+ pkt->setDataFromBlock(blk->data, blkSize);
+ }
+ }
+
+ if (!respond && is_timing && is_deferred) {
+ // if it's a deferred timing snoop to which we are not
+ // responding, then we've made a copy of both the request and
+ // the packet, delete them here
+ assert(pkt->needsResponse());
+ delete pkt->req;
+ delete pkt;
+ }
+
+ // Do this last in case it deallocates block data or something
+ // like that
+ if (invalidate) {
+ invalidateBlock(blk);
+ }
+
+ DPRINTF(Cache, "new state is %s\n", blk->print());
+
+ return snoop_delay;
+}
+
+
+void
+Cache::recvTimingSnoopReq(PacketPtr pkt)
+{
+ DPRINTF(CacheVerbose, "%s for %s addr %#llx size %d\n", __func__,
+ pkt->cmdString(), pkt->getAddr(), pkt->getSize());
+
+ // Snoops shouldn't happen when bypassing caches
+ assert(!system->bypassCaches());
+
+ // no need to snoop requests that are not in range
+ if (!inRange(pkt->getAddr())) {
+ return;
+ }
+
+ bool is_secure = pkt->isSecure();
+ CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
+
+ Addr blk_addr = blockAlign(pkt->getAddr());
+ MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
+
+ // Update the latency cost of the snoop so that the crossbar can
+ // account for it. Do not overwrite what other neighbouring caches
+ // have already done, rather take the maximum. The update is
+ // tentative, for cases where we return before an upward snoop
+ // happens below.
+ pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay,
+ lookupLatency * clockPeriod());
+
+ // Inform request(Prefetch, CleanEvict or Writeback) from below of
+ // MSHR hit, set setBlockCached.
+ if (mshr && pkt->mustCheckAbove()) {
+ DPRINTF(Cache, "Setting block cached for %s from"
+ "lower cache on mshr hit %#x\n",
+ pkt->cmdString(), pkt->getAddr());
+ pkt->setBlockCached();
+ return;
+ }
+
+ // Let the MSHR itself track the snoop and decide whether we want
+ // to go ahead and do the regular cache snoop
+ if (mshr && mshr->handleSnoop(pkt, order++)) {
+ DPRINTF(Cache, "Deferring snoop on in-service MSHR to blk %#llx (%s)."
+ "mshrs: %s\n", blk_addr, is_secure ? "s" : "ns",
+ mshr->print());
+
+ if (mshr->getNumTargets() > numTarget)
+ warn("allocating bonus target for snoop"); //handle later
+ return;
+ }
+
+ //We also need to check the writeback buffers and handle those
+ std::vector<MSHR *> writebacks;
+ if (writeBuffer.findMatches(blk_addr, is_secure, writebacks)) {
+ DPRINTF(Cache, "Snoop hit in writeback to addr %#llx (%s)\n",
+ pkt->getAddr(), is_secure ? "s" : "ns");
+
+ // Look through writebacks for any cachable writes.
+ // We should only ever find a single match
+ assert(writebacks.size() == 1);
+ MSHR *wb_entry = writebacks[0];
+ // Expect to see only Writebacks and/or CleanEvicts here, both of
+ // which should not be generated for uncacheable data.
+ assert(!wb_entry->isUncacheable());
+ // There should only be a single request responsible for generating
+ // Writebacks/CleanEvicts.
+ assert(wb_entry->getNumTargets() == 1);
+ PacketPtr wb_pkt = wb_entry->getTarget()->pkt;
+ assert(wb_pkt->isEviction());
+
+ if (pkt->isEviction()) {
+ // if the block is found in the write queue, set the BLOCK_CACHED
+ // flag for Writeback/CleanEvict snoop. On return the snoop will
+ // propagate the BLOCK_CACHED flag in Writeback packets and prevent
+ // any CleanEvicts from travelling down the memory hierarchy.
+ pkt->setBlockCached();
+ DPRINTF(Cache, "Squashing %s from lower cache on writequeue hit"
+ " %#x\n", pkt->cmdString(), pkt->getAddr());
+ return;
+ }
+
+ // conceptually writebacks are no different to other blocks in
+ // this cache, so the behaviour is modelled after handleSnoop,
+ // the difference being that instead of querying the block
+ // state to determine if it is dirty and writable, we use the
+ // command and fields of the writeback packet
+ bool respond = wb_pkt->cmd == MemCmd::WritebackDirty &&
+ pkt->needsResponse() && pkt->cmd != MemCmd::InvalidateReq;
+ bool have_writable = !wb_pkt->hasSharers();
+ bool invalidate = pkt->isInvalidate();
+
+ if (!pkt->req->isUncacheable() && pkt->isRead() && !invalidate) {
+ assert(!pkt->needsWritable());
+ pkt->setHasSharers();
+ wb_pkt->setHasSharers();
+ }
+
+ if (respond) {
+ pkt->setCacheResponding();
+
+ if (have_writable) {
+ pkt->setResponderHadWritable();
+ }
+
+ doTimingSupplyResponse(pkt, wb_pkt->getConstPtr<uint8_t>(),
+ false, false);
+ }
+
+ if (invalidate) {
+ // Invalidation trumps our writeback... discard here
+ // Note: markInService will remove entry from writeback buffer.
+ markInService(wb_entry, false);
+ delete wb_pkt;
+ }
+ }
+
+ // If this was a shared writeback, there may still be
+ // other shared copies above that require invalidation.
+ // We could be more selective and return here if the
+ // request is non-exclusive or if the writeback is
+ // exclusive.
+ uint32_t snoop_delay = handleSnoop(pkt, blk, true, false, false);
+
+ // Override what we did when we first saw the snoop, as we now
+ // also have the cost of the upwards snoops to account for
+ pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay, snoop_delay +
+ lookupLatency * clockPeriod());
+}
+
+bool
+Cache::CpuSidePort::recvTimingSnoopResp(PacketPtr pkt)
+{
+ // Express snoop responses from master to slave, e.g., from L1 to L2
+ cache->recvTimingSnoopResp(pkt);
+ return true;
+}
+
+Tick
+Cache::recvAtomicSnoop(PacketPtr pkt)
+{
+ // Snoops shouldn't happen when bypassing caches
+ assert(!system->bypassCaches());
+
+ // no need to snoop requests that are not in range.
+ if (!inRange(pkt->getAddr())) {
+ return 0;
+ }
+
+ CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
+ uint32_t snoop_delay = handleSnoop(pkt, blk, false, false, false);
+ return snoop_delay + lookupLatency * clockPeriod();
+}
+
+
+MSHR *
+Cache::getNextMSHR()
+{
+ // Check both MSHR queue and write buffer for potential requests,
+ // note that null does not mean there is no request, it could
+ // simply be that it is not ready
+ MSHR *miss_mshr = mshrQueue.getNextMSHR();
+ MSHR *write_mshr = writeBuffer.getNextMSHR();
+
+ // If we got a write buffer request ready, first priority is a
+ // full write buffer, otherwhise we favour the miss requests
+ if (write_mshr &&
+ ((writeBuffer.isFull() && writeBuffer.inServiceEntries == 0) ||
+ !miss_mshr)) {
+ // need to search MSHR queue for conflicting earlier miss.
+ MSHR *conflict_mshr =
+ mshrQueue.findPending(write_mshr->blkAddr,
+ write_mshr->isSecure);
+
+ if (conflict_mshr && conflict_mshr->order < write_mshr->order) {
+ // Service misses in order until conflict is cleared.
+ return conflict_mshr;
+
+ // @todo Note that we ignore the ready time of the conflict here
+ }
+
+ // No conflicts; issue write
+ return write_mshr;
+ } else if (miss_mshr) {
+ // need to check for conflicting earlier writeback
+ MSHR *conflict_mshr =
+ writeBuffer.findPending(miss_mshr->blkAddr,
+ miss_mshr->isSecure);
+ if (conflict_mshr) {
+ // not sure why we don't check order here... it was in the
+ // original code but commented out.
+
+ // The only way this happens is if we are
+ // doing a write and we didn't have permissions
+ // then subsequently saw a writeback (owned got evicted)
+ // We need to make sure to perform the writeback first
+ // To preserve the dirty data, then we can issue the write
+
+ // should we return write_mshr here instead? I.e. do we
+ // have to flush writes in order? I don't think so... not
+ // for Alpha anyway. Maybe for x86?
+ return conflict_mshr;
+
+ // @todo Note that we ignore the ready time of the conflict here
+ }
+
+ // No conflicts; issue read
+ return miss_mshr;
+ }
+
+ // fall through... no pending requests. Try a prefetch.
+ assert(!miss_mshr && !write_mshr);
+ if (prefetcher && mshrQueue.canPrefetch()) {
+ // If we have a miss queue slot, we can try a prefetch
+ PacketPtr pkt = prefetcher->getPacket();
+ if (pkt) {
+ Addr pf_addr = blockAlign(pkt->getAddr());
+ if (!tags->findBlock(pf_addr, pkt->isSecure()) &&
+ !mshrQueue.findMatch(pf_addr, pkt->isSecure()) &&
+ !writeBuffer.findMatch(pf_addr, pkt->isSecure())) {
+ // Update statistic on number of prefetches issued
+ // (hwpf_mshr_misses)
+ assert(pkt->req->masterId() < system->maxMasters());
+ mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
+
+ // allocate an MSHR and return it, note
+ // that we send the packet straight away, so do not
+ // schedule the send
+ return allocateMissBuffer(pkt, curTick(), false);
+ } else {
+ // free the request and packet
+ delete pkt->req;
+ delete pkt;
+ }
+ }
+ }
+
+ return NULL;
+}
+
+bool
+Cache::isCachedAbove(PacketPtr pkt, bool is_timing) const
+{
+ if (!forwardSnoops)
+ return false;
+ // Mirroring the flow of HardPFReqs, the cache sends CleanEvict and
+ // Writeback snoops into upper level caches to check for copies of the
+ // same block. Using the BLOCK_CACHED flag with the Writeback/CleanEvict
+ // packet, the cache can inform the crossbar below of presence or absence
+ // of the block.
+ if (is_timing) {
+ Packet snoop_pkt(pkt, true, false);
+ snoop_pkt.setExpressSnoop();
+ // Assert that packet is either Writeback or CleanEvict and not a
+ // prefetch request because prefetch requests need an MSHR and may
+ // generate a snoop response.
+ assert(pkt->isEviction());
+ snoop_pkt.senderState = NULL;
+ cpuSidePort->sendTimingSnoopReq(&snoop_pkt);
+ // Writeback/CleanEvict snoops do not generate a snoop response.
+ assert(!(snoop_pkt.cacheResponding()));
+ return snoop_pkt.isBlockCached();
+ } else {
+ cpuSidePort->sendAtomicSnoop(pkt);
+ return pkt->isBlockCached();
+ }
+}
+
+PacketPtr
+Cache::getTimingPacket()
+{
+ MSHR *mshr = getNextMSHR();
+
+ if (mshr == NULL) {
+ return NULL;
+ }
+
+ // use request from 1st target
+ PacketPtr tgt_pkt = mshr->getTarget()->pkt;
+ PacketPtr pkt = NULL;
+
+ DPRINTF(CachePort, "%s %s for addr %#llx size %d\n", __func__,
+ tgt_pkt->cmdString(), tgt_pkt->getAddr(), tgt_pkt->getSize());
+
+ CacheBlk *blk = tags->findBlock(mshr->blkAddr, mshr->isSecure);
+
+ if (tgt_pkt->cmd == MemCmd::HardPFReq && forwardSnoops) {
+ // We need to check the caches above us to verify that
+ // they don't have a copy of this block in the dirty state
+ // at the moment. Without this check we could get a stale
+ // copy from memory that might get used in place of the
+ // dirty one.
+ Packet snoop_pkt(tgt_pkt, true, false);
+ snoop_pkt.setExpressSnoop();
+ // We are sending this packet upwards, but if it hits we will
+ // get a snoop response that we end up treating just like a
+ // normal response, hence it needs the MSHR as its sender
+ // state
+ snoop_pkt.senderState = mshr;
+ cpuSidePort->sendTimingSnoopReq(&snoop_pkt);
+
+ // Check to see if the prefetch was squashed by an upper cache (to
+ // prevent us from grabbing the line) or if a Check to see if a
+ // writeback arrived between the time the prefetch was placed in
+ // the MSHRs and when it was selected to be sent or if the
+ // prefetch was squashed by an upper cache.
+
+ // It is important to check cacheResponding before
+ // prefetchSquashed. If another cache has committed to
+ // responding, it will be sending a dirty response which will
+ // arrive at the MSHR allocated for this request. Checking the
+ // prefetchSquash first may result in the MSHR being
+ // prematurely deallocated.
+ if (snoop_pkt.cacheResponding()) {
+ auto M5_VAR_USED r = outstandingSnoop.insert(snoop_pkt.req);
+ assert(r.second);
+
+ // if we are getting a snoop response with no sharers it
+ // will be allocated as Modified
+ bool pending_modified_resp = !snoop_pkt.hasSharers();
+ markInService(mshr, pending_modified_resp);
+
+ DPRINTF(Cache, "Upward snoop of prefetch for addr"
+ " %#x (%s) hit\n",
+ tgt_pkt->getAddr(), tgt_pkt->isSecure()? "s": "ns");
+ return NULL;
+ }
+
+ if (snoop_pkt.isBlockCached() || blk != NULL) {
+ DPRINTF(Cache, "Block present, prefetch squashed by cache. "
+ "Deallocating mshr target %#x.\n",
+ mshr->blkAddr);
+ // Deallocate the mshr target
+ if (mshr->queue->forceDeallocateTarget(mshr)) {
+ // Clear block if this deallocation resulted freed an
+ // mshr when all had previously been utilized
+ clearBlocked((BlockedCause)(mshr->queue->index));
+ }
+ return NULL;
+ }
+ }
+
+ if (mshr->isForwardNoResponse()) {
+ // no response expected, just forward packet as it is
+ assert(tags->findBlock(mshr->blkAddr, mshr->isSecure) == NULL);
+ pkt = tgt_pkt;
+ } else {
+ pkt = getBusPacket(tgt_pkt, blk, mshr->needsWritable());
+
+ mshr->isForward = (pkt == NULL);
+
+ if (mshr->isForward) {
+ // not a cache block request, but a response is expected
+ // make copy of current packet to forward, keep current
+ // copy for response handling
+ pkt = new Packet(tgt_pkt, false, true);
+ if (pkt->isWrite()) {
+ pkt->setData(tgt_pkt->getConstPtr<uint8_t>());
+ }
+ }
+ }
+
+ assert(pkt != NULL);
+ // play it safe and append (rather than set) the sender state, as
+ // forwarded packets may already have existing state
+ pkt->pushSenderState(mshr);
+ return pkt;
+}
+
+
+Tick
+Cache::nextMSHRReadyTime() const
+{
+ Tick nextReady = std::min(mshrQueue.nextMSHRReadyTime(),
+ writeBuffer.nextMSHRReadyTime());
+
+ // Don't signal prefetch ready time if no MSHRs available
+ // Will signal once enoguh MSHRs are deallocated
+ if (prefetcher && mshrQueue.canPrefetch()) {
+ nextReady = std::min(nextReady,
+ prefetcher->nextPrefetchReadyTime());
+ }
+
+ return nextReady;
+}
+
+void
+Cache::serialize(CheckpointOut &cp) const
+{
+ bool dirty(isDirty());
+
+ if (dirty) {
+ warn("*** The cache still contains dirty data. ***\n");
+ warn(" Make sure to drain the system using the correct flags.\n");
+ warn(" This checkpoint will not restore correctly and dirty data in "
+ "the cache will be lost!\n");
+ }
+
+ // Since we don't checkpoint the data in the cache, any dirty data
+ // will be lost when restoring from a checkpoint of a system that
+ // wasn't drained properly. Flag the checkpoint as invalid if the
+ // cache contains dirty data.
+ bool bad_checkpoint(dirty);
+ SERIALIZE_SCALAR(bad_checkpoint);
+}
+
+void
+Cache::unserialize(CheckpointIn &cp)
+{
+ bool bad_checkpoint;
+ UNSERIALIZE_SCALAR(bad_checkpoint);
+ if (bad_checkpoint) {
+ fatal("Restoring from checkpoints with dirty caches is not supported "
+ "in the classic memory system. Please remove any caches or "
+ " drain them properly before taking checkpoints.\n");
+ }
+}
+
+///////////////
+//
+// CpuSidePort
+//
+///////////////
+
+AddrRangeList
+Cache::CpuSidePort::getAddrRanges() const
+{
+ return cache->getAddrRanges();
+}
+
+bool
+Cache::CpuSidePort::recvTimingReq(PacketPtr pkt)
+{
+ assert(!cache->system->bypassCaches());
+
+ bool success = false;
+
+ // always let packets through if an upstream cache has committed
+ // to responding, even if blocked (we should technically look at
+ // the isExpressSnoop flag, but it is set by the cache itself, and
+ // consequently we have to rely on the cacheResponding flag)
+ if (pkt->cacheResponding()) {
+ // do not change the current retry state
+ bool M5_VAR_USED bypass_success = cache->recvTimingReq(pkt);
+ assert(bypass_success);
+ return true;
+ } else if (blocked || mustSendRetry) {
+ // either already committed to send a retry, or blocked
+ success = false;
+ } else {
+ // pass it on to the cache, and let the cache decide if we
+ // have to retry or not
+ success = cache->recvTimingReq(pkt);
+ }
+
+ // remember if we have to retry
+ mustSendRetry = !success;
+ return success;
+}
+
+Tick
+Cache::CpuSidePort::recvAtomic(PacketPtr pkt)
+{
+ return cache->recvAtomic(pkt);
+}
+
+void
+Cache::CpuSidePort::recvFunctional(PacketPtr pkt)
+{
+ // functional request
+ cache->functionalAccess(pkt, true);
+}
+
+Cache::
+CpuSidePort::CpuSidePort(const std::string &_name, Cache *_cache,
+ const std::string &_label)
+ : BaseCache::CacheSlavePort(_name, _cache, _label), cache(_cache)
+{
+}
+
+Cache*
+CacheParams::create()
+{
+ assert(tags);
+
+ return new Cache(this);
+}
+///////////////
+//
+// MemSidePort
+//
+///////////////
+
+bool
+Cache::MemSidePort::recvTimingResp(PacketPtr pkt)
+{
+ cache->recvTimingResp(pkt);
+ return true;
+}
+
+// Express snooping requests to memside port
+void
+Cache::MemSidePort::recvTimingSnoopReq(PacketPtr pkt)
+{
+ // handle snooping requests
+ cache->recvTimingSnoopReq(pkt);
+}
+
+Tick
+Cache::MemSidePort::recvAtomicSnoop(PacketPtr pkt)
+{
+ return cache->recvAtomicSnoop(pkt);
+}
+
+void
+Cache::MemSidePort::recvFunctionalSnoop(PacketPtr pkt)
+{
+ // functional snoop (note that in contrast to atomic we don't have
+ // a specific functionalSnoop method, as they have the same
+ // behaviour regardless)
+ cache->functionalAccess(pkt, false);
+}
+
+void
+Cache::CacheReqPacketQueue::sendDeferredPacket()
+{
+ // sanity check
+ assert(!waitingOnRetry);
+
+ // there should never be any deferred request packets in the
+ // queue, instead we resly on the cache to provide the packets
+ // from the MSHR queue or write queue
+ assert(deferredPacketReadyTime() == MaxTick);
+
+ // check for request packets (requests & writebacks)
+ PacketPtr pkt = cache.getTimingPacket();
+ if (pkt == NULL) {
+ // can happen if e.g. we attempt a writeback and fail, but
+ // before the retry, the writeback is eliminated because
+ // we snoop another cache's ReadEx.
+ } else {
+ MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
+ // in most cases getTimingPacket allocates a new packet, and
+ // we must delete it unless it is successfully sent
+ bool delete_pkt = !mshr->isForwardNoResponse();
+
+ // let our snoop responses go first if there are responses to
+ // the same addresses we are about to writeback, note that
+ // this creates a dependency between requests and snoop
+ // responses, but that should not be a problem since there is
+ // a chain already and the key is that the snoop responses can
+ // sink unconditionally
+ if (snoopRespQueue.hasAddr(pkt->getAddr())) {
+ DPRINTF(CachePort, "Waiting for snoop response to be sent\n");
+ Tick when = snoopRespQueue.deferredPacketReadyTime();
+ schedSendEvent(when);
+
+ if (delete_pkt)
+ delete pkt;
+
+ return;
+ }
+
+
+ waitingOnRetry = !masterPort.sendTimingReq(pkt);
+
+ if (waitingOnRetry) {
+ DPRINTF(CachePort, "now waiting on a retry\n");
+ if (delete_pkt) {
+ // we are awaiting a retry, but we
+ // delete the packet and will be creating a new packet
+ // when we get the opportunity
+ delete pkt;
+ }
+ // note that we have now masked any requestBus and
+ // schedSendEvent (we will wait for a retry before
+ // doing anything), and this is so even if we do not
+ // care about this packet and might override it before
+ // it gets retried
+ } else {
+ // As part of the call to sendTimingReq the packet is
+ // forwarded to all neighbouring caches (and any caches
+ // above them) as a snoop. Thus at this point we know if
+ // any of the neighbouring caches are responding, and if
+ // so, we know it is dirty, and we can determine if it is
+ // being passed as Modified, making our MSHR the ordering
+ // point
+ bool pending_modified_resp = !pkt->hasSharers() &&
+ pkt->cacheResponding();
+
+ cache.markInService(mshr, pending_modified_resp);
+ }
+ }
+
+ // if we succeeded and are not waiting for a retry, schedule the
+ // next send considering when the next MSHR is ready, note that
+ // snoop responses have their own packet queue and thus schedule
+ // their own events
+ if (!waitingOnRetry) {
+ schedSendEvent(cache.nextMSHRReadyTime());
+ }
+}
+
+Cache::
+MemSidePort::MemSidePort(const std::string &_name, Cache *_cache,
+ const std::string &_label)
+ : BaseCache::CacheMasterPort(_name, _cache, _reqQueue, _snoopRespQueue),
+ _reqQueue(*_cache, *this, _snoopRespQueue, _label),
+ _snoopRespQueue(*_cache, *this, _label), cache(_cache)
+{
+}
projects / gem5.git / blobdiff