1/*
2 * Copyright (c) 2010-2015 ARM Limited
3 * All rights reserved.
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2002-2005 The Regents of The University of Michigan
15 * Copyright (c) 2010,2015 Advanced Micro Devices, Inc.
16 * All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions are
20 * met: redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer;
22 * redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution;
25 * neither the name of the copyright holders nor the names of its
26 * contributors may be used to endorse or promote products derived from
27 * this software without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 *
41 * Authors: Erik Hallnor
42 * Dave Greene
43 * Nathan Binkert
44 * Steve Reinhardt
45 * Ron Dreslinski
46 * Andreas Sandberg
47 */
48
49/**
50 * @file
51 * Cache definitions.
52 */
53
54#include "mem/cache/cache.hh"
55
56#include "base/misc.hh"
57#include "base/types.hh"
58#include "debug/Cache.hh"
59#include "debug/CachePort.hh"
60#include "debug/CacheTags.hh"
61#include "mem/cache/blk.hh"
62#include "mem/cache/mshr.hh"
63#include "mem/cache/prefetch/base.hh"
64#include "sim/sim_exit.hh"
65
66Cache::Cache(const CacheParams *p)
67 : BaseCache(p, p->system->cacheLineSize()),
68 tags(p->tags),
69 prefetcher(p->prefetcher),
70 doFastWrites(true),
71 prefetchOnAccess(p->prefetch_on_access)
72{
73 tempBlock = new CacheBlk();
74 tempBlock->data = new uint8_t[blkSize];
75
76 cpuSidePort = new CpuSidePort(p->name + ".cpu_side", this,
77 "CpuSidePort");
78 memSidePort = new MemSidePort(p->name + ".mem_side", this,
79 "MemSidePort");
80
81 tags->setCache(this);
82 if (prefetcher)
83 prefetcher->setCache(this);
84}
85
86Cache::~Cache()
87{
88 delete [] tempBlock->data;
89 delete tempBlock;
90
91 delete cpuSidePort;
92 delete memSidePort;
93}
94
95void
96Cache::regStats()
97{
98 BaseCache::regStats();
99}
100
101void
102Cache::cmpAndSwap(CacheBlk *blk, PacketPtr pkt)
103{
104 assert(pkt->isRequest());
105
106 uint64_t overwrite_val;
107 bool overwrite_mem;
108 uint64_t condition_val64;
109 uint32_t condition_val32;
110
111 int offset = tags->extractBlkOffset(pkt->getAddr());
112 uint8_t *blk_data = blk->data + offset;
113
114 assert(sizeof(uint64_t) >= pkt->getSize());
115
116 overwrite_mem = true;
117 // keep a copy of our possible write value, and copy what is at the
118 // memory address into the packet
119 pkt->writeData((uint8_t *)&overwrite_val);
120 pkt->setData(blk_data);
121
122 if (pkt->req->isCondSwap()) {
123 if (pkt->getSize() == sizeof(uint64_t)) {
124 condition_val64 = pkt->req->getExtraData();
125 overwrite_mem = !std::memcmp(&condition_val64, blk_data,
126 sizeof(uint64_t));
127 } else if (pkt->getSize() == sizeof(uint32_t)) {
128 condition_val32 = (uint32_t)pkt->req->getExtraData();
129 overwrite_mem = !std::memcmp(&condition_val32, blk_data,
130 sizeof(uint32_t));
131 } else
132 panic("Invalid size for conditional read/write\n");
133 }
134
135 if (overwrite_mem) {
136 std::memcpy(blk_data, &overwrite_val, pkt->getSize());
137 blk->status |= BlkDirty;
138 }
139}
140
141
142void
143Cache::satisfyCpuSideRequest(PacketPtr pkt, CacheBlk *blk,
144 bool deferred_response, bool pending_downgrade)
145{
146 assert(pkt->isRequest());
147
148 assert(blk && blk->isValid());
149 // Occasionally this is not true... if we are a lower-level cache
150 // satisfying a string of Read and ReadEx requests from
151 // upper-level caches, a Read will mark the block as shared but we
152 // can satisfy a following ReadEx anyway since we can rely on the
153 // Read requester(s) to have buffered the ReadEx snoop and to
154 // invalidate their blocks after receiving them.
155 // assert(!pkt->needsExclusive() || blk->isWritable());
156 assert(pkt->getOffset(blkSize) + pkt->getSize() <= blkSize);
157
158 // Check RMW operations first since both isRead() and
159 // isWrite() will be true for them
160 if (pkt->cmd == MemCmd::SwapReq) {
161 cmpAndSwap(blk, pkt);
162 } else if (pkt->isWrite()) {
163 assert(blk->isWritable());
164 // Write or WriteLine at the first cache with block in Exclusive
165 if (blk->checkWrite(pkt)) {
166 pkt->writeDataToBlock(blk->data, blkSize);
167 }
168 // Always mark the line as dirty even if we are a failed
169 // StoreCond so we supply data to any snoops that have
170 // appended themselves to this cache before knowing the store
171 // will fail.
172 blk->status |= BlkDirty;
173 DPRINTF(Cache, "%s for %s addr %#llx size %d (write)\n", __func__,
174 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
175 } else if (pkt->isRead()) {
176 if (pkt->isLLSC()) {
177 blk->trackLoadLocked(pkt);
178 }
179 pkt->setDataFromBlock(blk->data, blkSize);
180 // determine if this read is from a (coherent) cache, or not
181 // by looking at the command type; we could potentially add a
182 // packet attribute such as 'FromCache' to make this check a
183 // bit cleaner
184 if (pkt->cmd == MemCmd::ReadExReq ||
185 pkt->cmd == MemCmd::ReadSharedReq ||
186 pkt->cmd == MemCmd::ReadCleanReq ||
187 pkt->cmd == MemCmd::SCUpgradeFailReq) {
188 assert(pkt->getSize() == blkSize);
189 // special handling for coherent block requests from
190 // upper-level caches
191 if (pkt->needsExclusive()) {
192 // sanity check
193 assert(pkt->cmd == MemCmd::ReadExReq ||
194 pkt->cmd == MemCmd::SCUpgradeFailReq);
195
196 // if we have a dirty copy, make sure the recipient
197 // keeps it marked dirty
198 if (blk->isDirty()) {
199 pkt->assertMemInhibit();
200 }
201 // on ReadExReq we give up our copy unconditionally
202 if (blk != tempBlock)
203 tags->invalidate(blk);
204 blk->invalidate();
205 } else if (blk->isWritable() && !pending_downgrade &&
206 !pkt->sharedAsserted() &&
207 pkt->cmd != MemCmd::ReadCleanReq) {
208 // we can give the requester an exclusive copy (by not
209 // asserting shared line) on a read request if:
210 // - we have an exclusive copy at this level (& below)
211 // - we don't have a pending snoop from below
212 // signaling another read request
213 // - no other cache above has a copy (otherwise it
214 // would have asseretd shared line on request)
215 // - we are not satisfying an instruction fetch (this
216 // prevents dirty data in the i-cache)
217
218 if (blk->isDirty()) {
219 // special considerations if we're owner:
220 if (!deferred_response) {
221 // if we are responding immediately and can
222 // signal that we're transferring ownership
223 // along with exclusivity, do so
224 pkt->assertMemInhibit();
225 blk->status &= ~BlkDirty;
226 } else {
227 // if we're responding after our own miss,
228 // there's a window where the recipient didn't
229 // know it was getting ownership and may not
230 // have responded to snoops correctly, so we
231 // can't pass off ownership *or* exclusivity
232 pkt->assertShared();
233 }
234 }
235 } else {
236 // otherwise only respond with a shared copy
237 pkt->assertShared();
238 }
239 }
240 } else {
241 // Upgrade or Invalidate, since we have it Exclusively (E or
242 // M), we ack then invalidate.
243 assert(pkt->isUpgrade() || pkt->isInvalidate());
244 assert(blk != tempBlock);
245 tags->invalidate(blk);
246 blk->invalidate();
247 DPRINTF(Cache, "%s for %s addr %#llx size %d (invalidation)\n",
248 __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize());
249 }
250}
251
252
253/////////////////////////////////////////////////////
254//
255// MSHR helper functions
256//
257/////////////////////////////////////////////////////
258
259
260void
261Cache::markInService(MSHR *mshr, bool pending_dirty_resp)
262{
263 markInServiceInternal(mshr, pending_dirty_resp);
264}
265
266/////////////////////////////////////////////////////
267//
268// Access path: requests coming in from the CPU side
269//
270/////////////////////////////////////////////////////
271
272bool
273Cache::access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat,
274 PacketList &writebacks)
275{
276 // sanity check
277 assert(pkt->isRequest());
278
279 chatty_assert(!(isReadOnly && pkt->isWrite()),
280 "Should never see a write in a read-only cache %s\n",
281 name());
282
283 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
284 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
285
286 if (pkt->req->isUncacheable()) {
287 DPRINTF(Cache, "%s%s addr %#llx uncacheable\n", pkt->cmdString(),
288 pkt->req->isInstFetch() ? " (ifetch)" : "",
289 pkt->getAddr());
290
291 // flush and invalidate any existing block
292 CacheBlk *old_blk(tags->findBlock(pkt->getAddr(), pkt->isSecure()));
293 if (old_blk && old_blk->isValid()) {
294 if (old_blk->isDirty())
295 writebacks.push_back(writebackBlk(old_blk));
296 else
297 writebacks.push_back(cleanEvictBlk(old_blk));
298 tags->invalidate(old_blk);
299 old_blk->invalidate();
300 }
301
302 blk = NULL;
303 // lookupLatency is the latency in case the request is uncacheable.
304 lat = lookupLatency;
305 return false;
306 }
307
308 ContextID id = pkt->req->hasContextId() ?
309 pkt->req->contextId() : InvalidContextID;
310 // Here lat is the value passed as parameter to accessBlock() function
311 // that can modify its value.
312 blk = tags->accessBlock(pkt->getAddr(), pkt->isSecure(), lat, id);
313
314 DPRINTF(Cache, "%s%s addr %#llx size %d (%s) %s\n", pkt->cmdString(),
315 pkt->req->isInstFetch() ? " (ifetch)" : "",
316 pkt->getAddr(), pkt->getSize(), pkt->isSecure() ? "s" : "ns",
317 blk ? "hit " + blk->print() : "miss");
318
319
320 if (pkt->evictingBlock()) {
321 // We check for presence of block in above caches before issuing
322 // Writeback or CleanEvict to write buffer. Therefore the only
323 // possible cases can be of a CleanEvict packet coming from above
324 // encountering a Writeback generated in this cache peer cache and
325 // waiting in the write buffer. Cases of upper level peer caches
326 // generating CleanEvict and Writeback or simply CleanEvict and
327 // CleanEvict almost simultaneously will be caught by snoops sent out
328 // by crossbar.
329 std::vector<MSHR *> outgoing;
330 if (writeBuffer.findMatches(pkt->getAddr(), pkt->isSecure(),
331 outgoing)) {
332 assert(outgoing.size() == 1);
333 PacketPtr wbPkt = outgoing[0]->getTarget()->pkt;
334 assert(pkt->cmd == MemCmd::CleanEvict &&
335 wbPkt->cmd == MemCmd::Writeback);
336 // As the CleanEvict is coming from above, it would have snooped
337 // into other peer caches of the same level while traversing the
338 // crossbar. If a copy of the block had been found, the CleanEvict
339 // would have been deleted in the crossbar. Now that the
340 // CleanEvict is here we can be sure none of the other upper level
341 // caches connected to this cache have the block, so we can clear
342 // the BLOCK_CACHED flag in the Writeback if set and discard the
343 // CleanEvict by returning true.
344 wbPkt->clearBlockCached();
345 return true;
346 }
347 }
348
349 // Writeback handling is special case. We can write the block into
350 // the cache without having a writeable copy (or any copy at all).
351 if (pkt->cmd == MemCmd::Writeback) {
352 assert(blkSize == pkt->getSize());
353 if (blk == NULL) {
354 // need to do a replacement
355 blk = allocateBlock(pkt->getAddr(), pkt->isSecure(), writebacks);
356 if (blk == NULL) {
357 // no replaceable block available: give up, fwd to next level.
358 incMissCount(pkt);
359 return false;
360 }
361 tags->insertBlock(pkt, blk);
362
363 blk->status = (BlkValid | BlkReadable);
364 if (pkt->isSecure()) {
365 blk->status |= BlkSecure;
366 }
367 }
368 blk->status |= BlkDirty;
369 // if shared is not asserted we got the writeback in modified
370 // state, if it is asserted we are in the owned state
371 if (!pkt->sharedAsserted()) {
372 blk->status |= BlkWritable;
373 }
374 // nothing else to do; writeback doesn't expect response
375 assert(!pkt->needsResponse());
376 std::memcpy(blk->data, pkt->getConstPtr<uint8_t>(), blkSize);
377 DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
378 incHitCount(pkt);
379 return true;
380 } else if (pkt->cmd == MemCmd::CleanEvict) {
381 if (blk != NULL) {
382 // Found the block in the tags, need to stop CleanEvict from
383 // propagating further down the hierarchy. Returning true will
384 // treat the CleanEvict like a satisfied write request and delete
385 // it.
386 return true;
387 }
388 // We didn't find the block here, propagate the CleanEvict further
389 // down the memory hierarchy. Returning false will treat the CleanEvict
390 // like a Writeback which could not find a replaceable block so has to
391 // go to next level.
392 return false;
393 } else if ((blk != NULL) &&
394 (pkt->needsExclusive() ? blk->isWritable()
395 : blk->isReadable())) {
396 // OK to satisfy access
397 incHitCount(pkt);
398 satisfyCpuSideRequest(pkt, blk);
399 return true;
400 }
401
402 // Can't satisfy access normally... either no block (blk == NULL)
403 // or have block but need exclusive & only have shared.
404
405 incMissCount(pkt);
406
407 if (blk == NULL && pkt->isLLSC() && pkt->isWrite()) {
408 // complete miss on store conditional... just give up now
409 pkt->req->setExtraData(0);
410 return true;
411 }
412
413 return false;
414}
415
416
417class ForwardResponseRecord : public Packet::SenderState
418{
419 public:
420
421 ForwardResponseRecord() {}
422};
423
424void
425Cache::doWritebacks(PacketList& writebacks, Tick forward_time)
426{
427 while (!writebacks.empty()) {
428 PacketPtr wbPkt = writebacks.front();
429 // We use forwardLatency here because we are copying writebacks to
430 // write buffer. Call isCachedAbove for both Writebacks and
431 // CleanEvicts. If isCachedAbove returns true we set BLOCK_CACHED flag
432 // in Writebacks and discard CleanEvicts.
433 if (isCachedAbove(wbPkt)) {
434 if (wbPkt->cmd == MemCmd::CleanEvict) {
435 // Delete CleanEvict because cached copies exist above. The
436 // packet destructor will delete the request object because
437 // this is a non-snoop request packet which does not require a
438 // response.
439 delete wbPkt;
440 } else {
441 // Set BLOCK_CACHED flag in Writeback and send below, so that
442 // the Writeback does not reset the bit corresponding to this
443 // address in the snoop filter below.
444 wbPkt->setBlockCached();
445 allocateWriteBuffer(wbPkt, forward_time);
446 }
447 } else {
448 // If the block is not cached above, send packet below. Both
449 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
450 // reset the bit corresponding to this address in the snoop filter
451 // below.
452 allocateWriteBuffer(wbPkt, forward_time);
453 }
454 writebacks.pop_front();
455 }
456}
457
458void
459Cache::doWritebacksAtomic(PacketList& writebacks)
460{
461 while (!writebacks.empty()) {
462 PacketPtr wbPkt = writebacks.front();
463 // Call isCachedAbove for both Writebacks and CleanEvicts. If
464 // isCachedAbove returns true we set BLOCK_CACHED flag in Writebacks
465 // and discard CleanEvicts.
466 if (isCachedAbove(wbPkt, false)) {
467 if (wbPkt->cmd == MemCmd::Writeback) {
468 // Set BLOCK_CACHED flag in Writeback and send below,
469 // so that the Writeback does not reset the bit
470 // corresponding to this address in the snoop filter
471 // below. We can discard CleanEvicts because cached
472 // copies exist above. Atomic mode isCachedAbove
473 // modifies packet to set BLOCK_CACHED flag
474 memSidePort->sendAtomic(wbPkt);
475 }
476 } else {
477 // If the block is not cached above, send packet below. Both
478 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
479 // reset the bit corresponding to this address in the snoop filter
480 // below.
481 memSidePort->sendAtomic(wbPkt);
482 }
483 writebacks.pop_front();
484 // In case of CleanEvicts, the packet destructor will delete the
485 // request object because this is a non-snoop request packet which
486 // does not require a response.
487 delete wbPkt;
488 }
489}
490
491
492void
493Cache::recvTimingSnoopResp(PacketPtr pkt)
494{
495 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
496 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
497
498 assert(pkt->isResponse());
499
500 // must be cache-to-cache response from upper to lower level
501 ForwardResponseRecord *rec =
502 dynamic_cast<ForwardResponseRecord *>(pkt->senderState);
503 assert(!system->bypassCaches());
504
505 if (rec == NULL) {
506 // @todo What guarantee do we have that this HardPFResp is
507 // actually for this cache, and not a cache closer to the
508 // memory?
509 assert(pkt->cmd == MemCmd::HardPFResp);
510 // Check if it's a prefetch response and handle it. We shouldn't
511 // get any other kinds of responses without FRRs.
512 DPRINTF(Cache, "Got prefetch response from above for addr %#llx (%s)\n",
513 pkt->getAddr(), pkt->isSecure() ? "s" : "ns");
514 recvTimingResp(pkt);
515 return;
516 }
517
518 pkt->popSenderState();
519 delete rec;
520 // forwardLatency is set here because there is a response from an
521 // upper level cache.
522 // To pay the delay that occurs if the packet comes from the bus,
523 // we charge also headerDelay.
524 Tick snoop_resp_time = clockEdge(forwardLatency) + pkt->headerDelay;
525 // Reset the timing of the packet.
526 pkt->headerDelay = pkt->payloadDelay = 0;
527 memSidePort->schedTimingSnoopResp(pkt, snoop_resp_time);
528}
529
530void
531Cache::promoteWholeLineWrites(PacketPtr pkt)
532{
533 // Cache line clearing instructions
534 if (doFastWrites && (pkt->cmd == MemCmd::WriteReq) &&
535 (pkt->getSize() == blkSize) && (pkt->getOffset(blkSize) == 0)) {
536 pkt->cmd = MemCmd::WriteLineReq;
537 DPRINTF(Cache, "packet promoted from Write to WriteLineReq\n");
538 }
539}
540
541bool
542Cache::recvTimingReq(PacketPtr pkt)
543{
544 DPRINTF(CacheTags, "%s tags: %s\n", __func__, tags->print());
545
546 assert(pkt->isRequest());
547
548 // Just forward the packet if caches are disabled.
549 if (system->bypassCaches()) {
550 // @todo This should really enqueue the packet rather
551 bool M5_VAR_USED success = memSidePort->sendTimingReq(pkt);
552 assert(success);
553 return true;
554 }
555
556 promoteWholeLineWrites(pkt);
557
558 if (pkt->memInhibitAsserted()) {
559 // a cache above us (but not where the packet came from) is
560 // responding to the request
561 DPRINTF(Cache, "mem inhibited on addr %#llx (%s): not responding\n",
562 pkt->getAddr(), pkt->isSecure() ? "s" : "ns");
563
564 // if the packet needs exclusive, and the cache that has
565 // promised to respond (setting the inhibit flag) is not
566 // providing exclusive (it is in O vs M state), we know that
567 // there may be other shared copies in the system; go out and
568 // invalidate them all
569 if (pkt->needsExclusive() && !pkt->isSupplyExclusive()) {
570 // create a downstream express snoop with cleared packet
571 // flags, there is no need to allocate any data as the
572 // packet is merely used to co-ordinate state transitions
573 Packet *snoop_pkt = new Packet(pkt, true, false);
574
575 // also reset the bus time that the original packet has
576 // not yet paid for
577 snoop_pkt->headerDelay = snoop_pkt->payloadDelay = 0;
578
579 // make this an instantaneous express snoop, and let the
580 // other caches in the system know that the packet is
581 // inhibited, because we have found the authorative copy
582 // (O) that will supply the right data
583 snoop_pkt->setExpressSnoop();
584 snoop_pkt->assertMemInhibit();
585
586 // this express snoop travels towards the memory, and at
587 // every crossbar it is snooped upwards thus reaching
588 // every cache in the system
589 bool M5_VAR_USED success = memSidePort->sendTimingReq(snoop_pkt);
590 // express snoops always succeed
591 assert(success);
592
593 // main memory will delete the packet
594 }
595
596 // queue for deletion, as the sending cache is still relying
597 // on the packet
598 pendingDelete.reset(pkt);
599
600 // no need to take any action in this particular cache as the
601 // caches along the path to memory are allowed to keep lines
602 // in a shared state, and a cache above us already committed
603 // to responding
604 return true;
605 }
606
607 // anything that is merely forwarded pays for the forward latency and
608 // the delay provided by the crossbar
609 Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
610
611 // We use lookupLatency here because it is used to specify the latency
612 // to access.
613 Cycles lat = lookupLatency;
614 CacheBlk *blk = NULL;
615 bool satisfied = false;
616 {
617 PacketList writebacks;
618 // Note that lat is passed by reference here. The function
619 // access() calls accessBlock() which can modify lat value.
620 satisfied = access(pkt, blk, lat, writebacks);
621
622 // copy writebacks to write buffer here to ensure they logically
623 // proceed anything happening below
624 doWritebacks(writebacks, forward_time);
625 }
626
627 // Here we charge the headerDelay that takes into account the latencies
628 // of the bus, if the packet comes from it.
629 // The latency charged it is just lat that is the value of lookupLatency
630 // modified by access() function, or if not just lookupLatency.
631 // In case of a hit we are neglecting response latency.
632 // In case of a miss we are neglecting forward latency.
633 Tick request_time = clockEdge(lat) + pkt->headerDelay;
634 // Here we reset the timing of the packet.
635 pkt->headerDelay = pkt->payloadDelay = 0;
636
637 // track time of availability of next prefetch, if any
638 Tick next_pf_time = MaxTick;
639
640 bool needsResponse = pkt->needsResponse();
641
642 if (satisfied) {
643 // should never be satisfying an uncacheable access as we
644 // flush and invalidate any existing block as part of the
645 // lookup
646 assert(!pkt->req->isUncacheable());
647
648 // hit (for all other request types)
649
650 if (prefetcher && (prefetchOnAccess || (blk && blk->wasPrefetched()))) {
651 if (blk)
652 blk->status &= ~BlkHWPrefetched;
653
654 // Don't notify on SWPrefetch
655 if (!pkt->cmd.isSWPrefetch())
656 next_pf_time = prefetcher->notify(pkt);
657 }
658
659 if (needsResponse) {
660 pkt->makeTimingResponse();
661 // @todo: Make someone pay for this
662 pkt->headerDelay = pkt->payloadDelay = 0;
663
664 // In this case we are considering request_time that takes
665 // into account the delay of the xbar, if any, and just
666 // lat, neglecting responseLatency, modelling hit latency
667 // just as lookupLatency or or the value of lat overriden
668 // by access(), that calls accessBlock() function.
669 cpuSidePort->schedTimingResp(pkt, request_time, true);
670 } else {
671 // queue the packet for deletion, as the sending cache is
672 // still relying on it; if the block is found in access(),
673 // CleanEvict and Writeback messages will be deleted
674 // here as well
675 pendingDelete.reset(pkt);
676 }
677 } else {
678 // miss
679
680 Addr blk_addr = blockAlign(pkt->getAddr());
681
682 // ignore any existing MSHR if we are dealing with an
683 // uncacheable request
684 MSHR *mshr = pkt->req->isUncacheable() ? nullptr :
685 mshrQueue.findMatch(blk_addr, pkt->isSecure());
686
687 // Software prefetch handling:
688 // To keep the core from waiting on data it won't look at
689 // anyway, send back a response with dummy data. Miss handling
690 // will continue asynchronously. Unfortunately, the core will
691 // insist upon freeing original Packet/Request, so we have to
692 // create a new pair with a different lifecycle. Note that this
693 // processing happens before any MSHR munging on the behalf of
694 // this request because this new Request will be the one stored
695 // into the MSHRs, not the original.
696 if (pkt->cmd.isSWPrefetch()) {
697 assert(needsResponse);
698 assert(pkt->req->hasPaddr());
699 assert(!pkt->req->isUncacheable());
700
701 // There's no reason to add a prefetch as an additional target
702 // to an existing MSHR. If an outstanding request is already
703 // in progress, there is nothing for the prefetch to do.
704 // If this is the case, we don't even create a request at all.
705 PacketPtr pf = nullptr;
706
707 if (!mshr) {
708 // copy the request and create a new SoftPFReq packet
709 RequestPtr req = new Request(pkt->req->getPaddr(),
710 pkt->req->getSize(),
711 pkt->req->getFlags(),
712 pkt->req->masterId());
713 pf = new Packet(req, pkt->cmd);
714 pf->allocate();
715 assert(pf->getAddr() == pkt->getAddr());
716 assert(pf->getSize() == pkt->getSize());
717 }
718
719 pkt->makeTimingResponse();
720 // for debugging, set all the bits in the response data
721 // (also keeps valgrind from complaining when debugging settings
722 // print out instruction results)
723 std::memset(pkt->getPtr<uint8_t>(), 0xFF, pkt->getSize());
724 // request_time is used here, taking into account lat and the delay
725 // charged if the packet comes from the xbar.
726 cpuSidePort->schedTimingResp(pkt, request_time, true);
727
728 // If an outstanding request is in progress (we found an
729 // MSHR) this is set to null
730 pkt = pf;
731 }
732
733 if (mshr) {
734 /// MSHR hit
735 /// @note writebacks will be checked in getNextMSHR()
736 /// for any conflicting requests to the same block
737
738 //@todo remove hw_pf here
739
740 // Coalesce unless it was a software prefetch (see above).
741 if (pkt) {
742 assert(pkt->cmd != MemCmd::Writeback);
743 // CleanEvicts corresponding to blocks which have outstanding
744 // requests in MSHRs can be deleted here.
745 if (pkt->cmd == MemCmd::CleanEvict) {
746 pendingDelete.reset(pkt);
747 } else {
748 DPRINTF(Cache, "%s coalescing MSHR for %s addr %#llx size %d\n",
749 __func__, pkt->cmdString(), pkt->getAddr(),
750 pkt->getSize());
751
752 assert(pkt->req->masterId() < system->maxMasters());
753 mshr_hits[pkt->cmdToIndex()][pkt->req->masterId()]++;
754 if (mshr->threadNum != 0/*pkt->req->threadId()*/) {
755 mshr->threadNum = -1;
756 }
757 // We use forward_time here because it is the same
758 // considering new targets. We have multiple
759 // requests for the same address here. It
760 // specifies the latency to allocate an internal
761 // buffer and to schedule an event to the queued
762 // port and also takes into account the additional
763 // delay of the xbar.
764 mshr->allocateTarget(pkt, forward_time, order++);
765 if (mshr->getNumTargets() == numTarget) {
766 noTargetMSHR = mshr;
767 setBlocked(Blocked_NoTargets);
768 // need to be careful with this... if this mshr isn't
769 // ready yet (i.e. time > curTick()), we don't want to
770 // move it ahead of mshrs that are ready
771 // mshrQueue.moveToFront(mshr);
772 }
773 }
774 // We should call the prefetcher reguardless if the request is
775 // satisfied or not, reguardless if the request is in the MSHR or
776 // not. The request could be a ReadReq hit, but still not
777 // satisfied (potentially because of a prior write to the same
778 // cache line. So, even when not satisfied, tehre is an MSHR
779 // already allocated for this, we need to let the prefetcher know
780 // about the request
781 if (prefetcher) {
782 // Don't notify on SWPrefetch
783 if (!pkt->cmd.isSWPrefetch())
784 next_pf_time = prefetcher->notify(pkt);
785 }
786 }
787 } else {
788 // no MSHR
789 assert(pkt->req->masterId() < system->maxMasters());
790 if (pkt->req->isUncacheable()) {
791 mshr_uncacheable[pkt->cmdToIndex()][pkt->req->masterId()]++;
792 } else {
793 mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
794 }
795
796 if (pkt->evictingBlock() ||
797 (pkt->req->isUncacheable() && pkt->isWrite())) {
798 // We use forward_time here because there is an
799 // uncached memory write, forwarded to WriteBuffer.
800 allocateWriteBuffer(pkt, forward_time);
801 } else {
802 if (blk && blk->isValid()) {
803 // should have flushed and have no valid block
804 assert(!pkt->req->isUncacheable());
805
806 // If we have a write miss to a valid block, we
807 // need to mark the block non-readable. Otherwise
808 // if we allow reads while there's an outstanding
809 // write miss, the read could return stale data
810 // out of the cache block... a more aggressive
811 // system could detect the overlap (if any) and
812 // forward data out of the MSHRs, but we don't do
813 // that yet. Note that we do need to leave the
814 // block valid so that it stays in the cache, in
815 // case we get an upgrade response (and hence no
816 // new data) when the write miss completes.
817 // As long as CPUs do proper store/load forwarding
818 // internally, and have a sufficiently weak memory
819 // model, this is probably unnecessary, but at some
820 // point it must have seemed like we needed it...
821 assert(pkt->needsExclusive());
822 assert(!blk->isWritable());
823 blk->status &= ~BlkReadable;
824 }
825 // Here we are using forward_time, modelling the latency of
826 // a miss (outbound) just as forwardLatency, neglecting the
827 // lookupLatency component.
828 allocateMissBuffer(pkt, forward_time);
829 }
830
831 if (prefetcher) {
832 // Don't notify on SWPrefetch
833 if (!pkt->cmd.isSWPrefetch())
834 next_pf_time = prefetcher->notify(pkt);
835 }
836 }
837 }
838
839 if (next_pf_time != MaxTick)
840 schedMemSideSendEvent(next_pf_time);
841
842 return true;
843}
844
845
846// See comment in cache.hh.
847PacketPtr
848Cache::getBusPacket(PacketPtr cpu_pkt, CacheBlk *blk,
849 bool needsExclusive) const
850{
851 bool blkValid = blk && blk->isValid();
852
853 if (cpu_pkt->req->isUncacheable()) {
854 // note that at the point we see the uncacheable request we
855 // flush any block, but there could be an outstanding MSHR,
856 // and the cache could have filled again before we actually
857 // send out the forwarded uncacheable request (blk could thus
858 // be non-null)
859 return NULL;
860 }
861
862 if (!blkValid &&
863 (cpu_pkt->isUpgrade() ||
864 cpu_pkt->evictingBlock())) {
865 // Writebacks that weren't allocated in access() and upgrades
866 // from upper-level caches that missed completely just go
867 // through.
868 return NULL;
869 }
870
871 assert(cpu_pkt->needsResponse());
872
873 MemCmd cmd;
874 // @TODO make useUpgrades a parameter.
875 // Note that ownership protocols require upgrade, otherwise a
876 // write miss on a shared owned block will generate a ReadExcl,
877 // which will clobber the owned copy.
878 const bool useUpgrades = true;
879 if (blkValid && useUpgrades) {
880 // only reason to be here is that blk is shared
881 // (read-only) and we need exclusive
882 assert(needsExclusive);
883 assert(!blk->isWritable());
884 cmd = cpu_pkt->isLLSC() ? MemCmd::SCUpgradeReq : MemCmd::UpgradeReq;
885 } else if (cpu_pkt->cmd == MemCmd::SCUpgradeFailReq ||
886 cpu_pkt->cmd == MemCmd::StoreCondFailReq) {
887 // Even though this SC will fail, we still need to send out the
888 // request and get the data to supply it to other snoopers in the case
889 // where the determination the StoreCond fails is delayed due to
890 // all caches not being on the same local bus.
891 cmd = MemCmd::SCUpgradeFailReq;
892 } else if (cpu_pkt->cmd == MemCmd::WriteLineReq) {
893 // forward as invalidate to all other caches, this gives us
894 // the line in exclusive state, and invalidates all other
895 // copies
896 cmd = MemCmd::InvalidateReq;
897 } else {
898 // block is invalid
899 cmd = needsExclusive ? MemCmd::ReadExReq :
900 (isReadOnly ? MemCmd::ReadCleanReq : MemCmd::ReadSharedReq);
901 }
902 PacketPtr pkt = new Packet(cpu_pkt->req, cmd, blkSize);
903
904 // if there are sharers in the upper levels, pass that info downstream
905 if (cpu_pkt->sharedAsserted()) {
906 // note that cpu_pkt may have spent a considerable time in the
907 // MSHR queue and that the information could possibly be out
908 // of date, however, there is no harm in conservatively
909 // assuming the block is shared
910 pkt->assertShared();
911 DPRINTF(Cache, "%s passing shared from %s to %s addr %#llx size %d\n",
912 __func__, cpu_pkt->cmdString(), pkt->cmdString(),
913 pkt->getAddr(), pkt->getSize());
914 }
915
916 // the packet should be block aligned
917 assert(pkt->getAddr() == blockAlign(pkt->getAddr()));
918
919 pkt->allocate();
920 DPRINTF(Cache, "%s created %s from %s for addr %#llx size %d\n",
921 __func__, pkt->cmdString(), cpu_pkt->cmdString(), pkt->getAddr(),
922 pkt->getSize());
923 return pkt;
924}
925
926
927Tick
928Cache::recvAtomic(PacketPtr pkt)
929{
930 // We are in atomic mode so we pay just for lookupLatency here.
931 Cycles lat = lookupLatency;
932 // @TODO: make this a parameter
933 bool last_level_cache = false;
934
935 // Forward the request if the system is in cache bypass mode.
936 if (system->bypassCaches())
937 return ticksToCycles(memSidePort->sendAtomic(pkt));
938
939 promoteWholeLineWrites(pkt);
940
941 if (pkt->memInhibitAsserted()) {
942 // have to invalidate ourselves and any lower caches even if
943 // upper cache will be responding
944 if (pkt->isInvalidate()) {
945 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
946 if (blk && blk->isValid()) {
947 tags->invalidate(blk);
948 blk->invalidate();
949 DPRINTF(Cache, "rcvd mem-inhibited %s on %#llx (%s):"
950 " invalidating\n",
951 pkt->cmdString(), pkt->getAddr(),
952 pkt->isSecure() ? "s" : "ns");
953 }
954 if (!last_level_cache) {
955 DPRINTF(Cache, "forwarding mem-inhibited %s on %#llx (%s)\n",
956 pkt->cmdString(), pkt->getAddr(),
957 pkt->isSecure() ? "s" : "ns");
958 lat += ticksToCycles(memSidePort->sendAtomic(pkt));
959 }
960 } else {
961 DPRINTF(Cache, "rcvd mem-inhibited %s on %#llx: not responding\n",
962 pkt->cmdString(), pkt->getAddr());
963 }
964
965 return lat * clockPeriod();
966 }
967
968 // should assert here that there are no outstanding MSHRs or
969 // writebacks... that would mean that someone used an atomic
970 // access in timing mode
971
972 CacheBlk *blk = NULL;
973 PacketList writebacks;
974 bool satisfied = access(pkt, blk, lat, writebacks);
975
976 // handle writebacks resulting from the access here to ensure they
977 // logically proceed anything happening below
978 doWritebacksAtomic(writebacks);
979
980 if (!satisfied) {
981 // MISS
982
983 PacketPtr bus_pkt = getBusPacket(pkt, blk, pkt->needsExclusive());
984
985 bool is_forward = (bus_pkt == NULL);
986
987 if (is_forward) {
988 // just forwarding the same request to the next level
989 // no local cache operation involved
990 bus_pkt = pkt;
991 }
992
993 DPRINTF(Cache, "Sending an atomic %s for %#llx (%s)\n",
994 bus_pkt->cmdString(), bus_pkt->getAddr(),
995 bus_pkt->isSecure() ? "s" : "ns");
996
997#if TRACING_ON
998 CacheBlk::State old_state = blk ? blk->status : 0;
999#endif
1000
1001 lat += ticksToCycles(memSidePort->sendAtomic(bus_pkt));
1002
1003 // We are now dealing with the response handling
1004 DPRINTF(Cache, "Receive response: %s for addr %#llx (%s) in state %i\n",
1005 bus_pkt->cmdString(), bus_pkt->getAddr(),
1006 bus_pkt->isSecure() ? "s" : "ns",
1007 old_state);
1008
1009 // If packet was a forward, the response (if any) is already
1010 // in place in the bus_pkt == pkt structure, so we don't need
1011 // to do anything. Otherwise, use the separate bus_pkt to
1012 // generate response to pkt and then delete it.
1013 if (!is_forward) {
1014 if (pkt->needsResponse()) {
1015 assert(bus_pkt->isResponse());
1016 if (bus_pkt->isError()) {
1017 pkt->makeAtomicResponse();
1018 pkt->copyError(bus_pkt);
1019 } else if (pkt->cmd == MemCmd::InvalidateReq) {
1020 if (blk) {
1021 // invalidate response to a cache that received
1022 // an invalidate request
1023 satisfyCpuSideRequest(pkt, blk);
1024 }
1025 } else if (pkt->cmd == MemCmd::WriteLineReq) {
1026 // note the use of pkt, not bus_pkt here.
1027
1028 // write-line request to the cache that promoted
1029 // the write to a whole line
1030 blk = handleFill(pkt, blk, writebacks);
1031 satisfyCpuSideRequest(pkt, blk);
1032 } else if (bus_pkt->isRead() ||
1033 bus_pkt->cmd == MemCmd::UpgradeResp) {
1034 // we're updating cache state to allow us to
1035 // satisfy the upstream request from the cache
1036 blk = handleFill(bus_pkt, blk, writebacks);
1037 satisfyCpuSideRequest(pkt, blk);
1038 } else {
1039 // we're satisfying the upstream request without
1040 // modifying cache state, e.g., a write-through
1041 pkt->makeAtomicResponse();
1042 }
1043 }
1044 delete bus_pkt;
1045 }
1046 }
1047
1048 // Note that we don't invoke the prefetcher at all in atomic mode.
1049 // It's not clear how to do it properly, particularly for
1050 // prefetchers that aggressively generate prefetch candidates and
1051 // rely on bandwidth contention to throttle them; these will tend
1052 // to pollute the cache in atomic mode since there is no bandwidth
1053 // contention. If we ever do want to enable prefetching in atomic
1054 // mode, though, this is the place to do it... see timingAccess()
1055 // for an example (though we'd want to issue the prefetch(es)
1056 // immediately rather than calling requestMemSideBus() as we do
1057 // there).
1058
1059 // Handle writebacks (from the response handling) if needed
1060 doWritebacksAtomic(writebacks);
1061
1062 if (pkt->needsResponse()) {
1063 pkt->makeAtomicResponse();
1064 }
1065
1066 return lat * clockPeriod();
1067}
1068
1069
1070void
1071Cache::functionalAccess(PacketPtr pkt, bool fromCpuSide)
1072{
1073 if (system->bypassCaches()) {
1074 // Packets from the memory side are snoop request and
1075 // shouldn't happen in bypass mode.
1076 assert(fromCpuSide);
1077
1078 // The cache should be flushed if we are in cache bypass mode,
1079 // so we don't need to check if we need to update anything.
1080 memSidePort->sendFunctional(pkt);
1081 return;
1082 }
1083
1084 Addr blk_addr = blockAlign(pkt->getAddr());
1085 bool is_secure = pkt->isSecure();
1086 CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
1087 MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
1088
1089 pkt->pushLabel(name());
1090
1091 CacheBlkPrintWrapper cbpw(blk);
1092
1093 // Note that just because an L2/L3 has valid data doesn't mean an
1094 // L1 doesn't have a more up-to-date modified copy that still
1095 // needs to be found. As a result we always update the request if
1096 // we have it, but only declare it satisfied if we are the owner.
1097
1098 // see if we have data at all (owned or otherwise)
1099 bool have_data = blk && blk->isValid()
1100 && pkt->checkFunctional(&cbpw, blk_addr, is_secure, blkSize,
1101 blk->data);
1102
1103 // data we have is dirty if marked as such or if valid & ownership
1104 // pending due to outstanding UpgradeReq
1105 bool have_dirty =
1106 have_data && (blk->isDirty() ||
1107 (mshr && mshr->inService && mshr->isPendingDirty()));
1108
1109 bool done = have_dirty
1110 || cpuSidePort->checkFunctional(pkt)
1111 || mshrQueue.checkFunctional(pkt, blk_addr)
1112 || writeBuffer.checkFunctional(pkt, blk_addr)
1113 || memSidePort->checkFunctional(pkt);
1114
1115 DPRINTF(Cache, "functional %s %#llx (%s) %s%s%s\n",
1116 pkt->cmdString(), pkt->getAddr(), is_secure ? "s" : "ns",
1117 (blk && blk->isValid()) ? "valid " : "",
1118 have_data ? "data " : "", done ? "done " : "");
1119
1120 // We're leaving the cache, so pop cache->name() label
1121 pkt->popLabel();
1122
1123 if (done) {
1124 pkt->makeResponse();
1125 } else {
1126 // if it came as a request from the CPU side then make sure it
1127 // continues towards the memory side
1128 if (fromCpuSide) {
1129 memSidePort->sendFunctional(pkt);
1130 } else if (forwardSnoops && cpuSidePort->isSnooping()) {
1131 // if it came from the memory side, it must be a snoop request
1132 // and we should only forward it if we are forwarding snoops
1133 cpuSidePort->sendFunctionalSnoop(pkt);
1134 }
1135 }
1136}
1137
1138
1139/////////////////////////////////////////////////////
1140//
1141// Response handling: responses from the memory side
1142//
1143/////////////////////////////////////////////////////
1144
1145
1146void
1147Cache::recvTimingResp(PacketPtr pkt)
1148{
1149 assert(pkt->isResponse());
1150
1151 // all header delay should be paid for by the crossbar, unless
1152 // this is a prefetch response from above
1153 panic_if(pkt->headerDelay != 0 && pkt->cmd != MemCmd::HardPFResp,
1154 "%s saw a non-zero packet delay\n", name());
1155
1156 MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
1157 bool is_error = pkt->isError();
1158
1159 assert(mshr);
1160
1161 if (is_error) {
1162 DPRINTF(Cache, "Cache received packet with error for addr %#llx (%s), "
1163 "cmd: %s\n", pkt->getAddr(), pkt->isSecure() ? "s" : "ns",
1164 pkt->cmdString());
1165 }
1166
1167 DPRINTF(Cache, "Handling response %s for addr %#llx size %d (%s)\n",
1168 pkt->cmdString(), pkt->getAddr(), pkt->getSize(),
1169 pkt->isSecure() ? "s" : "ns");
1170
1171 MSHRQueue *mq = mshr->queue;
1172 bool wasFull = mq->isFull();
1173
1174 if (mshr == noTargetMSHR) {
1175 // we always clear at least one target
1176 clearBlocked(Blocked_NoTargets);
1177 noTargetMSHR = NULL;
1178 }
1179
1180 // Initial target is used just for stats
1181 MSHR::Target *initial_tgt = mshr->getTarget();
1182 int stats_cmd_idx = initial_tgt->pkt->cmdToIndex();
1183 Tick miss_latency = curTick() - initial_tgt->recvTime;
1184 PacketList writebacks;
1185 // We need forward_time here because we have a call of
1186 // allocateWriteBuffer() that need this parameter to specify the
1187 // time to request the bus. In this case we use forward latency
1188 // because there is a writeback. We pay also here for headerDelay
1189 // that is charged of bus latencies if the packet comes from the
1190 // bus.
1191 Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
1192
1193 if (pkt->req->isUncacheable()) {
1194 assert(pkt->req->masterId() < system->maxMasters());
1195 mshr_uncacheable_lat[stats_cmd_idx][pkt->req->masterId()] +=
1196 miss_latency;
1197 } else {
1198 assert(pkt->req->masterId() < system->maxMasters());
1199 mshr_miss_latency[stats_cmd_idx][pkt->req->masterId()] +=
1200 miss_latency;
1201 }
1202
1203 // upgrade deferred targets if we got exclusive
1204 if (!pkt->sharedAsserted()) {
1205 mshr->promoteExclusive();
1206 }
1207
1208 bool is_fill = !mshr->isForward &&
1209 (pkt->isRead() || pkt->cmd == MemCmd::UpgradeResp);
1210
1211 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
1212
1213 if (is_fill && !is_error) {
1214 DPRINTF(Cache, "Block for addr %#llx being updated in Cache\n",
1215 pkt->getAddr());
1216
1217 blk = handleFill(pkt, blk, writebacks);
1218 assert(blk != NULL);
1219 }
1220
1221 // allow invalidation responses originating from write-line
1222 // requests to be discarded
1223 bool is_invalidate = pkt->isInvalidate();
1224
1225 // First offset for critical word first calculations
1226 int initial_offset = initial_tgt->pkt->getOffset(blkSize);
1227
1228 while (mshr->hasTargets()) {
1229 MSHR::Target *target = mshr->getTarget();
1230 Packet *tgt_pkt = target->pkt;
1231
1232 switch (target->source) {
1233 case MSHR::Target::FromCPU:
1234 Tick completion_time;
1235 // Here we charge on completion_time the delay of the xbar if the
1236 // packet comes from it, charged on headerDelay.
1237 completion_time = pkt->headerDelay;
1238
1239 // Software prefetch handling for cache closest to core
1240 if (tgt_pkt->cmd.isSWPrefetch()) {
1241 // a software prefetch would have already been ack'd immediately
1242 // with dummy data so the core would be able to retire it.
1243 // this request completes right here, so we deallocate it.
1244 delete tgt_pkt->req;
1245 delete tgt_pkt;
1246 break; // skip response
1247 }
1248
1249 // unlike the other packet flows, where data is found in other
1250 // caches or memory and brought back, write-line requests always
1251 // have the data right away, so the above check for "is fill?"
1252 // cannot actually be determined until examining the stored MSHR
1253 // state. We "catch up" with that logic here, which is duplicated
1254 // from above.
1255 if (tgt_pkt->cmd == MemCmd::WriteLineReq) {
1256 assert(!is_error);
1257 // we got the block in exclusive state, so promote any
1258 // deferred targets if possible
1259 mshr->promoteExclusive();
1260 // NB: we use the original packet here and not the response!
1261 blk = handleFill(tgt_pkt, blk, writebacks);
1262 assert(blk != NULL);
1263
1264 // treat as a fill, and discard the invalidation
1265 // response
1266 is_fill = true;
1267 is_invalidate = false;
1268 }
1269
1270 if (is_fill) {
1271 satisfyCpuSideRequest(tgt_pkt, blk,
1272 true, mshr->hasPostDowngrade());
1273
1274 // How many bytes past the first request is this one
1275 int transfer_offset =
1276 tgt_pkt->getOffset(blkSize) - initial_offset;
1277 if (transfer_offset < 0) {
1278 transfer_offset += blkSize;
1279 }
1280
1281 // If not critical word (offset) return payloadDelay.
1282 // responseLatency is the latency of the return path
1283 // from lower level caches/memory to an upper level cache or
1284 // the core.
1285 completion_time += clockEdge(responseLatency) +
1286 (transfer_offset ? pkt->payloadDelay : 0);
1287
1288 assert(!tgt_pkt->req->isUncacheable());
1289
1290 assert(tgt_pkt->req->masterId() < system->maxMasters());
1291 missLatency[tgt_pkt->cmdToIndex()][tgt_pkt->req->masterId()] +=
1292 completion_time - target->recvTime;
1293 } else if (pkt->cmd == MemCmd::UpgradeFailResp) {
1294 // failed StoreCond upgrade
1295 assert(tgt_pkt->cmd == MemCmd::StoreCondReq ||
1296 tgt_pkt->cmd == MemCmd::StoreCondFailReq ||
1297 tgt_pkt->cmd == MemCmd::SCUpgradeFailReq);
1298 // responseLatency is the latency of the return path
1299 // from lower level caches/memory to an upper level cache or
1300 // the core.
1301 completion_time += clockEdge(responseLatency) +
1302 pkt->payloadDelay;
1303 tgt_pkt->req->setExtraData(0);
1304 } else {
1305 // not a cache fill, just forwarding response
1306 // responseLatency is the latency of the return path
1307 // from lower level cahces/memory to the core.
1308 completion_time += clockEdge(responseLatency) +
1309 pkt->payloadDelay;
1310 if (pkt->isRead() && !is_error) {
1311 // sanity check
1312 assert(pkt->getAddr() == tgt_pkt->getAddr());
1313 assert(pkt->getSize() >= tgt_pkt->getSize());
1314
1315 tgt_pkt->setData(pkt->getConstPtr<uint8_t>());
1316 }
1317 }
1318 tgt_pkt->makeTimingResponse();
1319 // if this packet is an error copy that to the new packet
1320 if (is_error)
1321 tgt_pkt->copyError(pkt);
1322 if (tgt_pkt->cmd == MemCmd::ReadResp &&
1323 (is_invalidate || mshr->hasPostInvalidate())) {
1324 // If intermediate cache got ReadRespWithInvalidate,
1325 // propagate that. Response should not have
1326 // isInvalidate() set otherwise.
1327 tgt_pkt->cmd = MemCmd::ReadRespWithInvalidate;
1328 DPRINTF(Cache, "%s updated cmd to %s for addr %#llx\n",
1329 __func__, tgt_pkt->cmdString(), tgt_pkt->getAddr());
1330 }
1331 // Reset the bus additional time as it is now accounted for
1332 tgt_pkt->headerDelay = tgt_pkt->payloadDelay = 0;
1333 cpuSidePort->schedTimingResp(tgt_pkt, completion_time, true);
1334 break;
1335
1336 case MSHR::Target::FromPrefetcher:
1337 assert(tgt_pkt->cmd == MemCmd::HardPFReq);
1338 if (blk)
1339 blk->status |= BlkHWPrefetched;
1340 delete tgt_pkt->req;
1341 delete tgt_pkt;
1342 break;
1343
1344 case MSHR::Target::FromSnoop:
1345 // I don't believe that a snoop can be in an error state
1346 assert(!is_error);
1347 // response to snoop request
1348 DPRINTF(Cache, "processing deferred snoop...\n");
1349 assert(!(is_invalidate && !mshr->hasPostInvalidate()));
1350 handleSnoop(tgt_pkt, blk, true, true, mshr->hasPostInvalidate());
1351 break;
1352
1353 default:
1354 panic("Illegal target->source enum %d\n", target->source);
1355 }
1356
1357 mshr->popTarget();
1358 }
1359
1360 if (blk && blk->isValid()) {
1361 // an invalidate response stemming from a write line request
1362 // should not invalidate the block, so check if the
1363 // invalidation should be discarded
1364 if (is_invalidate || mshr->hasPostInvalidate()) {
1365 assert(blk != tempBlock);
1366 tags->invalidate(blk);
1367 blk->invalidate();
1368 } else if (mshr->hasPostDowngrade()) {
1369 blk->status &= ~BlkWritable;
1370 }
1371 }
1372
1373 if (mshr->promoteDeferredTargets()) {
1374 // avoid later read getting stale data while write miss is
1375 // outstanding.. see comment in timingAccess()
1376 if (blk) {
1377 blk->status &= ~BlkReadable;
1378 }
1379 mq = mshr->queue;
1380 mq->markPending(mshr);
1381 schedMemSideSendEvent(clockEdge() + pkt->payloadDelay);
1382 } else {
1383 mq->deallocate(mshr);
1384 if (wasFull && !mq->isFull()) {
1385 clearBlocked((BlockedCause)mq->index);
1386 }
1387
1388 // Request the bus for a prefetch if this deallocation freed enough
1389 // MSHRs for a prefetch to take place
1390 if (prefetcher && mq == &mshrQueue && mshrQueue.canPrefetch()) {
1391 Tick next_pf_time = std::max(prefetcher->nextPrefetchReadyTime(),
1392 clockEdge());
1393 if (next_pf_time != MaxTick)
1394 schedMemSideSendEvent(next_pf_time);
1395 }
1396 }
1397 // reset the xbar additional timinig as it is now accounted for
1398 pkt->headerDelay = pkt->payloadDelay = 0;
1399
1400 // copy writebacks to write buffer
1401 doWritebacks(writebacks, forward_time);
1402
1403 // if we used temp block, check to see if its valid and then clear it out
1404 if (blk == tempBlock && tempBlock->isValid()) {
1405 // We use forwardLatency here because we are copying
1406 // Writebacks/CleanEvicts to write buffer. It specifies the latency to
1407 // allocate an internal buffer and to schedule an event to the
1408 // queued port.
1409 if (blk->isDirty()) {
1410 PacketPtr wbPkt = writebackBlk(blk);
1411 allocateWriteBuffer(wbPkt, forward_time);
1412 // Set BLOCK_CACHED flag if cached above.
1413 if (isCachedAbove(wbPkt))
1414 wbPkt->setBlockCached();
1415 } else {
1416 PacketPtr wcPkt = cleanEvictBlk(blk);
1417 // Check to see if block is cached above. If not allocate
1418 // write buffer
1419 if (isCachedAbove(wcPkt))
1420 delete wcPkt;
1421 else
1422 allocateWriteBuffer(wcPkt, forward_time);
1423 }
1424 blk->invalidate();
1425 }
1426
1427 DPRINTF(Cache, "Leaving %s with %s for addr %#llx\n", __func__,
1428 pkt->cmdString(), pkt->getAddr());
1429 delete pkt;
1430}
1431
1432PacketPtr
1433Cache::writebackBlk(CacheBlk *blk)
1434{
1435 chatty_assert(!isReadOnly, "Writeback from read-only cache");
1436 assert(blk && blk->isValid() && blk->isDirty());
1437
1438 writebacks[Request::wbMasterId]++;
1439
1440 Request *writebackReq =
1441 new Request(tags->regenerateBlkAddr(blk->tag, blk->set), blkSize, 0,
1442 Request::wbMasterId);
1443 if (blk->isSecure())
1444 writebackReq->setFlags(Request::SECURE);
1445
1446 writebackReq->taskId(blk->task_id);
1447 blk->task_id= ContextSwitchTaskId::Unknown;
1448 blk->tickInserted = curTick();
1449
1450 PacketPtr writeback = new Packet(writebackReq, MemCmd::Writeback);
1451 if (blk->isWritable()) {
1452 // not asserting shared means we pass the block in modified
1453 // state, mark our own block non-writeable
1454 blk->status &= ~BlkWritable;
1455 } else {
1456 // we are in the owned state, tell the receiver
1457 writeback->assertShared();
1458 }
1459
1460 writeback->allocate();
1461 std::memcpy(writeback->getPtr<uint8_t>(), blk->data, blkSize);
1462
1463 blk->status &= ~BlkDirty;
1464 return writeback;
1465}
1466
1467PacketPtr
1468Cache::cleanEvictBlk(CacheBlk *blk)
1469{
1470 assert(blk && blk->isValid() && !blk->isDirty());
1471 // Creating a zero sized write, a message to the snoop filter
1472 Request *req =
1473 new Request(tags->regenerateBlkAddr(blk->tag, blk->set), blkSize, 0,
1474 Request::wbMasterId);
1475 if (blk->isSecure())
1476 req->setFlags(Request::SECURE);
1477
1478 req->taskId(blk->task_id);
1479 blk->task_id = ContextSwitchTaskId::Unknown;
1480 blk->tickInserted = curTick();
1481
1482 PacketPtr pkt = new Packet(req, MemCmd::CleanEvict);
1483 pkt->allocate();
1484 DPRINTF(Cache, "%s%s %x Create CleanEvict\n", pkt->cmdString(),
1485 pkt->req->isInstFetch() ? " (ifetch)" : "",
1486 pkt->getAddr());
1487
1488 return pkt;
1489}
1490
1491void
1492Cache::memWriteback()
1493{
1494 CacheBlkVisitorWrapper visitor(*this, &Cache::writebackVisitor);
1495 tags->forEachBlk(visitor);
1496}
1497
1498void
1499Cache::memInvalidate()
1500{
1501 CacheBlkVisitorWrapper visitor(*this, &Cache::invalidateVisitor);
1502 tags->forEachBlk(visitor);
1503}
1504
1505bool
1506Cache::isDirty() const
1507{
1508 CacheBlkIsDirtyVisitor visitor;
1509 tags->forEachBlk(visitor);
1510
1511 return visitor.isDirty();
1512}
1513
1514bool
1515Cache::writebackVisitor(CacheBlk &blk)
1516{
1517 if (blk.isDirty()) {
1518 assert(blk.isValid());
1519
1520 Request request(tags->regenerateBlkAddr(blk.tag, blk.set),
1521 blkSize, 0, Request::funcMasterId);
1522 request.taskId(blk.task_id);
1523
1524 Packet packet(&request, MemCmd::WriteReq);
1525 packet.dataStatic(blk.data);
1526
1527 memSidePort->sendFunctional(&packet);
1528
1529 blk.status &= ~BlkDirty;
1530 }
1531
1532 return true;
1533}
1534
1535bool
1536Cache::invalidateVisitor(CacheBlk &blk)
1537{
1538
1539 if (blk.isDirty())
1540 warn_once("Invalidating dirty cache lines. Expect things to break.\n");
1541
1542 if (blk.isValid()) {
1543 assert(!blk.isDirty());
1544 tags->invalidate(&blk);
1545 blk.invalidate();
1546 }
1547
1548 return true;
1549}
1550
1551CacheBlk*
1552Cache::allocateBlock(Addr addr, bool is_secure, PacketList &writebacks)
1553{
1554 CacheBlk *blk = tags->findVictim(addr);
1555
1556 // It is valid to return NULL if there is no victim
1557 if (!blk)
1558 return nullptr;
1559
1560 if (blk->isValid()) {
1561 Addr repl_addr = tags->regenerateBlkAddr(blk->tag, blk->set);
1562 MSHR *repl_mshr = mshrQueue.findMatch(repl_addr, blk->isSecure());
1563 if (repl_mshr) {
1564 // must be an outstanding upgrade request
1565 // on a block we're about to replace...
1566 assert(!blk->isWritable() || blk->isDirty());
1567 assert(repl_mshr->needsExclusive());
1568 // too hard to replace block with transient state
1569 // allocation failed, block not inserted
1570 return NULL;
1571 } else {
1572 DPRINTF(Cache, "replacement: replacing %#llx (%s) with %#llx (%s): %s\n",
1573 repl_addr, blk->isSecure() ? "s" : "ns",
1574 addr, is_secure ? "s" : "ns",
1575 blk->isDirty() ? "writeback" : "clean");
1576
1577 // Will send up Writeback/CleanEvict snoops via isCachedAbove
1578 // when pushing this writeback list into the write buffer.
1579 if (blk->isDirty()) {
1580 // Save writeback packet for handling by caller
1581 writebacks.push_back(writebackBlk(blk));
1582 } else {
1583 writebacks.push_back(cleanEvictBlk(blk));
1584 }
1585 }
1586 }
1587
1588 return blk;
1589}
1590
1591
1592// Note that the reason we return a list of writebacks rather than
1593// inserting them directly in the write buffer is that this function
1594// is called by both atomic and timing-mode accesses, and in atomic
1595// mode we don't mess with the write buffer (we just perform the
1596// writebacks atomically once the original request is complete).
1597CacheBlk*
1598Cache::handleFill(PacketPtr pkt, CacheBlk *blk, PacketList &writebacks)
1599{
1600 assert(pkt->isResponse() || pkt->cmd == MemCmd::WriteLineReq);
1601 Addr addr = pkt->getAddr();
1602 bool is_secure = pkt->isSecure();
1603#if TRACING_ON
1604 CacheBlk::State old_state = blk ? blk->status : 0;
1605#endif
1606
1607 // When handling a fill, discard any CleanEvicts for the
1608 // same address in write buffer.
1609 Addr M5_VAR_USED blk_addr = blockAlign(pkt->getAddr());
1610 std::vector<MSHR *> M5_VAR_USED wbs;
1611 assert (!writeBuffer.findMatches(blk_addr, is_secure, wbs));
1612
1613 if (blk == NULL) {
1614 // better have read new data...
1615 assert(pkt->hasData());
1616
1617 // only read responses and write-line requests have data;
1618 // note that we don't write the data here for write-line - that
1619 // happens in the subsequent satisfyCpuSideRequest.
1620 assert(pkt->isRead() || pkt->cmd == MemCmd::WriteLineReq);
1621
1622 // need to do a replacement
1623 blk = allocateBlock(addr, is_secure, writebacks);
1624 if (blk == NULL) {
1625 // No replaceable block... just use temporary storage to
1626 // complete the current request and then get rid of it
1627 assert(!tempBlock->isValid());
1628 blk = tempBlock;
1629 tempBlock->set = tags->extractSet(addr);
1630 tempBlock->tag = tags->extractTag(addr);
1631 // @todo: set security state as well...
1632 DPRINTF(Cache, "using temp block for %#llx (%s)\n", addr,
1633 is_secure ? "s" : "ns");
1634 } else {
1635 tags->insertBlock(pkt, blk);
1636 }
1637
1638 // we should never be overwriting a valid block
1639 assert(!blk->isValid());
1640 } else {
1641 // existing block... probably an upgrade
1642 assert(blk->tag == tags->extractTag(addr));
1643 // either we're getting new data or the block should already be valid
1644 assert(pkt->hasData() || blk->isValid());
1645 // don't clear block status... if block is already dirty we
1646 // don't want to lose that
1647 }
1648
1649 if (is_secure)
1650 blk->status |= BlkSecure;
1651 blk->status |= BlkValid | BlkReadable;
1652
1653 // sanity check for whole-line writes, which should always be
1654 // marked as writable as part of the fill, and then later marked
1655 // dirty as part of satisfyCpuSideRequest
1656 if (pkt->cmd == MemCmd::WriteLineReq) {
1657 assert(!pkt->sharedAsserted());
1658 // at the moment other caches do not respond to the
1659 // invalidation requests corresponding to a whole-line write
1660 assert(!pkt->memInhibitAsserted());
1661 }
1662
1663 if (!pkt->sharedAsserted()) {
1664 // we could get non-shared responses from memory (rather than
1665 // a cache) even in a read-only cache, note that we set this
1666 // bit even for a read-only cache as we use it to represent
1667 // the exclusive state
1668 blk->status |= BlkWritable;
1669
1670 // If we got this via cache-to-cache transfer (i.e., from a
1671 // cache that was an owner) and took away that owner's copy,
1672 // then we need to write it back. Normally this happens
1673 // anyway as a side effect of getting a copy to write it, but
1674 // there are cases (such as failed store conditionals or
1675 // compare-and-swaps) where we'll demand an exclusive copy but
1676 // end up not writing it.
1677 if (pkt->memInhibitAsserted()) {
1678 blk->status |= BlkDirty;
1679
1680 chatty_assert(!isReadOnly, "Should never see dirty snoop response "
1681 "in read-only cache %s\n", name());
1682 }
1683 }
1684
1685 DPRINTF(Cache, "Block addr %#llx (%s) moving from state %x to %s\n",
1686 addr, is_secure ? "s" : "ns", old_state, blk->print());
1687
1688 // if we got new data, copy it in (checking for a read response
1689 // and a response that has data is the same in the end)
1690 if (pkt->isRead()) {
1691 // sanity checks
1692 assert(pkt->hasData());
1693 assert(pkt->getSize() == blkSize);
1694
1695 std::memcpy(blk->data, pkt->getConstPtr<uint8_t>(), blkSize);
1696 }
1697 // We pay for fillLatency here.
1698 blk->whenReady = clockEdge() + fillLatency * clockPeriod() +
1699 pkt->payloadDelay;
1700
1701 return blk;
1702}
1703
1704
1705/////////////////////////////////////////////////////
1706//
1707// Snoop path: requests coming in from the memory side
1708//
1709/////////////////////////////////////////////////////
1710
1711void
1712Cache::doTimingSupplyResponse(PacketPtr req_pkt, const uint8_t *blk_data,
1713 bool already_copied, bool pending_inval)
1714{
1715 // sanity check
1716 assert(req_pkt->isRequest());
1717 assert(req_pkt->needsResponse());
1718
1719 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
1720 req_pkt->cmdString(), req_pkt->getAddr(), req_pkt->getSize());
1721 // timing-mode snoop responses require a new packet, unless we
1722 // already made a copy...
1723 PacketPtr pkt = req_pkt;
1724 if (!already_copied)
1725 // do not clear flags, and allocate space for data if the
1726 // packet needs it (the only packets that carry data are read
1727 // responses)
1728 pkt = new Packet(req_pkt, false, req_pkt->isRead());
1729
1730 assert(req_pkt->req->isUncacheable() || req_pkt->isInvalidate() ||
1731 pkt->sharedAsserted());
1732 pkt->makeTimingResponse();
1733 if (pkt->isRead()) {
1734 pkt->setDataFromBlock(blk_data, blkSize);
1735 }
1736 if (pkt->cmd == MemCmd::ReadResp && pending_inval) {
1737 // Assume we defer a response to a read from a far-away cache
1738 // A, then later defer a ReadExcl from a cache B on the same
1739 // bus as us. We'll assert MemInhibit in both cases, but in
1740 // the latter case MemInhibit will keep the invalidation from
1741 // reaching cache A. This special response tells cache A that
1742 // it gets the block to satisfy its read, but must immediately
1743 // invalidate it.
1744 pkt->cmd = MemCmd::ReadRespWithInvalidate;
1745 }
1746 // Here we consider forward_time, paying for just forward latency and
1747 // also charging the delay provided by the xbar.
1748 // forward_time is used as send_time in next allocateWriteBuffer().
1749 Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
1750 // Here we reset the timing of the packet.
1751 pkt->headerDelay = pkt->payloadDelay = 0;
1752 DPRINTF(Cache, "%s created response: %s addr %#llx size %d tick: %lu\n",
1753 __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize(),
1754 forward_time);
1755 memSidePort->schedTimingSnoopResp(pkt, forward_time, true);
1756}
1757
1758uint32_t
1759Cache::handleSnoop(PacketPtr pkt, CacheBlk *blk, bool is_timing,
1760 bool is_deferred, bool pending_inval)
1761{
1762 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
1763 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
1764 // deferred snoops can only happen in timing mode
1765 assert(!(is_deferred && !is_timing));
1766 // pending_inval only makes sense on deferred snoops
1767 assert(!(pending_inval && !is_deferred));
1768 assert(pkt->isRequest());
1769
1770 // the packet may get modified if we or a forwarded snooper
1771 // responds in atomic mode, so remember a few things about the
1772 // original packet up front
1773 bool invalidate = pkt->isInvalidate();
1774 bool M5_VAR_USED needs_exclusive = pkt->needsExclusive();
1775
1776 uint32_t snoop_delay = 0;
1777
1778 if (forwardSnoops) {
1779 // first propagate snoop upward to see if anyone above us wants to
1780 // handle it. save & restore packet src since it will get
1781 // rewritten to be relative to cpu-side bus (if any)
1782 bool alreadyResponded = pkt->memInhibitAsserted();
1783 if (is_timing) {
1784 // copy the packet so that we can clear any flags before
1785 // forwarding it upwards, we also allocate data (passing
1786 // the pointer along in case of static data), in case
1787 // there is a snoop hit in upper levels
1788 Packet snoopPkt(pkt, true, true);
1789 snoopPkt.setExpressSnoop();
1790 snoopPkt.pushSenderState(new ForwardResponseRecord());
1791 // the snoop packet does not need to wait any additional
1792 // time
1793 snoopPkt.headerDelay = snoopPkt.payloadDelay = 0;
1794 cpuSidePort->sendTimingSnoopReq(&snoopPkt);
1795
1796 // add the header delay (including crossbar and snoop
1797 // delays) of the upward snoop to the snoop delay for this
1798 // cache
1799 snoop_delay += snoopPkt.headerDelay;
1800
1801 if (snoopPkt.memInhibitAsserted()) {
1802 // cache-to-cache response from some upper cache
1803 assert(!alreadyResponded);
1804 pkt->assertMemInhibit();
1805 } else {
1806 // no cache (or anyone else for that matter) will
1807 // respond, so delete the ForwardResponseRecord here
1808 delete snoopPkt.popSenderState();
1809 }
1810 if (snoopPkt.sharedAsserted()) {
1811 pkt->assertShared();
1812 }
1813 // If this request is a prefetch or clean evict and an upper level
1814 // signals block present, make sure to propagate the block
1815 // presence to the requester.
1816 if (snoopPkt.isBlockCached()) {
1817 pkt->setBlockCached();
1818 }
1819 } else {
1820 cpuSidePort->sendAtomicSnoop(pkt);
1821 if (!alreadyResponded && pkt->memInhibitAsserted()) {
1822 // cache-to-cache response from some upper cache:
1823 // forward response to original requester
1824 assert(pkt->isResponse());
1825 }
1826 }
1827 }
1828
1829 if (!blk || !blk->isValid()) {
1830 DPRINTF(Cache, "%s snoop miss for %s addr %#llx size %d\n",
1831 __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize());
1832 return snoop_delay;
1833 } else {
1834 DPRINTF(Cache, "%s snoop hit for %s for addr %#llx size %d, "
1835 "old state is %s\n", __func__, pkt->cmdString(),
1836 pkt->getAddr(), pkt->getSize(), blk->print());
1837 }
1838
1839 chatty_assert(!(isReadOnly && blk->isDirty()),
1840 "Should never have a dirty block in a read-only cache %s\n",
1841 name());
1842
1843 // We may end up modifying both the block state and the packet (if
1844 // we respond in atomic mode), so just figure out what to do now
1845 // and then do it later. If we find dirty data while snooping for
1846 // an invalidate, we don't need to send a response. The
1847 // invalidation itself is taken care of below.
1848 bool respond = blk->isDirty() && pkt->needsResponse() &&
1849 pkt->cmd != MemCmd::InvalidateReq;
1850 bool have_exclusive = blk->isWritable();
1851
1852 // Invalidate any prefetch's from below that would strip write permissions
1853 // MemCmd::HardPFReq is only observed by upstream caches. After missing
1854 // above and in it's own cache, a new MemCmd::ReadReq is created that
1855 // downstream caches observe.
1856 if (pkt->mustCheckAbove()) {
1857 DPRINTF(Cache, "Found addr %#llx in upper level cache for snoop %s from"
1858 " lower cache\n", pkt->getAddr(), pkt->cmdString());
1859 pkt->setBlockCached();
1860 return snoop_delay;
1861 }
1862
1863 if (!pkt->req->isUncacheable() && pkt->isRead() && !invalidate) {
1864 // reading non-exclusive shared data, note that we retain
1865 // the block in owned state if it is dirty, with the response
1866 // taken care of below, and otherwhise simply downgrade to
1867 // shared
1868 assert(!needs_exclusive);
1869 pkt->assertShared();
1870 blk->status &= ~BlkWritable;
1871 }
1872
1873 if (respond) {
1874 // prevent anyone else from responding, cache as well as
1875 // memory, and also prevent any memory from even seeing the
1876 // request (with current inhibited semantics), note that this
1877 // applies both to reads and writes and that for writes it
1878 // works thanks to the fact that we still have dirty data and
1879 // will write it back at a later point
1880 pkt->assertMemInhibit();
1881 if (have_exclusive) {
1882 // in the case of an uncacheable request there is no point
1883 // in setting the exclusive flag, but since the recipient
1884 // does not care there is no harm in doing so, in any case
1885 // it is just a hint
1886 pkt->setSupplyExclusive();
1887 }
1888 if (is_timing) {
1889 doTimingSupplyResponse(pkt, blk->data, is_deferred, pending_inval);
1890 } else {
1891 pkt->makeAtomicResponse();
1892 pkt->setDataFromBlock(blk->data, blkSize);
1893 }
1894 }
1895
1896 if (!respond && is_timing && is_deferred) {
1897 // if it's a deferred timing snoop then we've made a copy of
1898 // both the request and the packet, and so if we're not using
1899 // those copies to respond and delete them here
1900 DPRINTF(Cache, "Deleting pkt %p and request %p for cmd %s addr: %p\n",
1901 pkt, pkt->req, pkt->cmdString(), pkt->getAddr());
1902
1903 // the packets needs a response (just not from us), so we also
1904 // need to delete the request and not rely on the packet
1905 // destructor
1906 assert(pkt->needsResponse());
1907 delete pkt->req;
1908 delete pkt;
1909 }
1910
1911 // Do this last in case it deallocates block data or something
1912 // like that
1913 if (invalidate) {
1914 if (blk != tempBlock)
1915 tags->invalidate(blk);
1916 blk->invalidate();
1917 }
1918
1919 DPRINTF(Cache, "new state is %s\n", blk->print());
1920
1921 return snoop_delay;
1922}
1923
1924
1925void
1926Cache::recvTimingSnoopReq(PacketPtr pkt)
1927{
1928 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
1929 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
1930
1931 // Snoops shouldn't happen when bypassing caches
1932 assert(!system->bypassCaches());
1933
1934 // no need to snoop requests that are not in range
1935 if (!inRange(pkt->getAddr())) {
1936 return;
1937 }
1938
1939 bool is_secure = pkt->isSecure();
1940 CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
1941
1942 Addr blk_addr = blockAlign(pkt->getAddr());
1943 MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
1944
1945 // Update the latency cost of the snoop so that the crossbar can
1946 // account for it. Do not overwrite what other neighbouring caches
1947 // have already done, rather take the maximum. The update is
1948 // tentative, for cases where we return before an upward snoop
1949 // happens below.
1950 pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay,
1951 lookupLatency * clockPeriod());
1952
1953 // Inform request(Prefetch, CleanEvict or Writeback) from below of
1954 // MSHR hit, set setBlockCached.
1955 if (mshr && pkt->mustCheckAbove()) {
1956 DPRINTF(Cache, "Setting block cached for %s from"
1957 "lower cache on mshr hit %#x\n",
1958 pkt->cmdString(), pkt->getAddr());
1959 pkt->setBlockCached();
1960 return;
1961 }
1962
1963 // Let the MSHR itself track the snoop and decide whether we want
1964 // to go ahead and do the regular cache snoop
1965 if (mshr && mshr->handleSnoop(pkt, order++)) {
1966 DPRINTF(Cache, "Deferring snoop on in-service MSHR to blk %#llx (%s)."
1967 "mshrs: %s\n", blk_addr, is_secure ? "s" : "ns",
1968 mshr->print());
1969
1970 if (mshr->getNumTargets() > numTarget)
1971 warn("allocating bonus target for snoop"); //handle later
1972 return;
1973 }
1974
1975 //We also need to check the writeback buffers and handle those
1976 std::vector<MSHR *> writebacks;
1977 if (writeBuffer.findMatches(blk_addr, is_secure, writebacks)) {
1978 DPRINTF(Cache, "Snoop hit in writeback to addr %#llx (%s)\n",
1979 pkt->getAddr(), is_secure ? "s" : "ns");
1980
1981 // Look through writebacks for any cachable writes.
1982 // We should only ever find a single match
1983 assert(writebacks.size() == 1);
1984 MSHR *wb_entry = writebacks[0];
1985 // Expect to see only Writebacks and/or CleanEvicts here, both of
1986 // which should not be generated for uncacheable data.
1987 assert(!wb_entry->isUncacheable());
1988 // There should only be a single request responsible for generating
1989 // Writebacks/CleanEvicts.
1990 assert(wb_entry->getNumTargets() == 1);
1991 PacketPtr wb_pkt = wb_entry->getTarget()->pkt;
1992 assert(wb_pkt->evictingBlock());
1993
1994 if (pkt->evictingBlock()) {
1995 // if the block is found in the write queue, set the BLOCK_CACHED
1996 // flag for Writeback/CleanEvict snoop. On return the snoop will
1997 // propagate the BLOCK_CACHED flag in Writeback packets and prevent
1998 // any CleanEvicts from travelling down the memory hierarchy.
1999 pkt->setBlockCached();
2000 DPRINTF(Cache, "Squashing %s from lower cache on writequeue hit"
2001 " %#x\n", pkt->cmdString(), pkt->getAddr());
2002 return;
2003 }
2004
2005 if (wb_pkt->cmd == MemCmd::Writeback) {
2006 assert(!pkt->memInhibitAsserted());
2007 pkt->assertMemInhibit();
2008 if (!pkt->needsExclusive()) {
2009 pkt->assertShared();
2010 // the writeback is no longer passing exclusivity (the
2011 // receiving cache should consider the block owned
2012 // rather than modified)
2013 wb_pkt->assertShared();
2014 } else {
2015 // if we're not asserting the shared line, we need to
2016 // invalidate our copy. we'll do that below as long as
2017 // the packet's invalidate flag is set...
2018 assert(pkt->isInvalidate());
2019 }
2020 doTimingSupplyResponse(pkt, wb_pkt->getConstPtr<uint8_t>(),
2021 false, false);
2022 } else {
2023 assert(wb_pkt->cmd == MemCmd::CleanEvict);
2024 // The cache technically holds the block until the
2025 // corresponding CleanEvict message reaches the crossbar
2026 // below. Therefore when a snoop encounters a CleanEvict
2027 // message we must set assertShared (just like when it
2028 // encounters a Writeback) to avoid the snoop filter
2029 // prematurely clearing the holder bit in the crossbar
2030 // below
2031 if (!pkt->needsExclusive())
2032 pkt->assertShared();
2033 else
2034 assert(pkt->isInvalidate());
2035 }
2036
2037 if (pkt->isInvalidate()) {
2038 // Invalidation trumps our writeback... discard here
2039 // Note: markInService will remove entry from writeback buffer.
2040 markInService(wb_entry, false);
2041 delete wb_pkt;
2042 }
2043 }
2044
2045 // If this was a shared writeback, there may still be
2046 // other shared copies above that require invalidation.
2047 // We could be more selective and return here if the
2048 // request is non-exclusive or if the writeback is
2049 // exclusive.
2050 uint32_t snoop_delay = handleSnoop(pkt, blk, true, false, false);
2051
2052 // Override what we did when we first saw the snoop, as we now
2053 // also have the cost of the upwards snoops to account for
2054 pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay, snoop_delay +
2055 lookupLatency * clockPeriod());
2056}
2057
2058bool
2059Cache::CpuSidePort::recvTimingSnoopResp(PacketPtr pkt)
2060{
2061 // Express snoop responses from master to slave, e.g., from L1 to L2
2062 cache->recvTimingSnoopResp(pkt);
2063 return true;
2064}
2065
2066Tick
2067Cache::recvAtomicSnoop(PacketPtr pkt)
2068{
2069 // Snoops shouldn't happen when bypassing caches
2070 assert(!system->bypassCaches());
2071
2072 // no need to snoop requests that are not in range.
2073 if (!inRange(pkt->getAddr())) {
2074 return 0;
2075 }
2076
2077 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
2078 uint32_t snoop_delay = handleSnoop(pkt, blk, false, false, false);
2079 return snoop_delay + lookupLatency * clockPeriod();
2080}
2081
2082
2083MSHR *
2084Cache::getNextMSHR()
2085{
2086 // Check both MSHR queue and write buffer for potential requests,
2087 // note that null does not mean there is no request, it could
2088 // simply be that it is not ready
2089 MSHR *miss_mshr = mshrQueue.getNextMSHR();
2090 MSHR *write_mshr = writeBuffer.getNextMSHR();
2091
2092 // If we got a write buffer request ready, first priority is a
2093 // full write buffer, otherwhise we favour the miss requests
2094 if (write_mshr &&
2095 ((writeBuffer.isFull() && writeBuffer.inServiceEntries == 0) ||
2096 !miss_mshr)) {
2097 // need to search MSHR queue for conflicting earlier miss.
2098 MSHR *conflict_mshr =
2099 mshrQueue.findPending(write_mshr->blkAddr,
2100 write_mshr->isSecure);
2101
2102 if (conflict_mshr && conflict_mshr->order < write_mshr->order) {
2103 // Service misses in order until conflict is cleared.
2104 return conflict_mshr;
2105
2106 // @todo Note that we ignore the ready time of the conflict here
2107 }
2108
2109 // No conflicts; issue write
2110 return write_mshr;
2111 } else if (miss_mshr) {
2112 // need to check for conflicting earlier writeback
2113 MSHR *conflict_mshr =
2114 writeBuffer.findPending(miss_mshr->blkAddr,
2115 miss_mshr->isSecure);
2116 if (conflict_mshr) {
2117 // not sure why we don't check order here... it was in the
2118 // original code but commented out.
2119
2120 // The only way this happens is if we are
2121 // doing a write and we didn't have permissions
2122 // then subsequently saw a writeback (owned got evicted)
2123 // We need to make sure to perform the writeback first
2124 // To preserve the dirty data, then we can issue the write
2125
2126 // should we return write_mshr here instead? I.e. do we
2127 // have to flush writes in order? I don't think so... not
2128 // for Alpha anyway. Maybe for x86?
2129 return conflict_mshr;
2130
2131 // @todo Note that we ignore the ready time of the conflict here
2132 }
2133
2134 // No conflicts; issue read
2135 return miss_mshr;
2136 }
2137
2138 // fall through... no pending requests. Try a prefetch.
2139 assert(!miss_mshr && !write_mshr);
2140 if (prefetcher && mshrQueue.canPrefetch()) {
2141 // If we have a miss queue slot, we can try a prefetch
2142 PacketPtr pkt = prefetcher->getPacket();
2143 if (pkt) {
2144 Addr pf_addr = blockAlign(pkt->getAddr());
2145 if (!tags->findBlock(pf_addr, pkt->isSecure()) &&
2146 !mshrQueue.findMatch(pf_addr, pkt->isSecure()) &&
2147 !writeBuffer.findMatch(pf_addr, pkt->isSecure())) {
2148 // Update statistic on number of prefetches issued
2149 // (hwpf_mshr_misses)
2150 assert(pkt->req->masterId() < system->maxMasters());
2151 mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
2152
2153 // allocate an MSHR and return it, note
2154 // that we send the packet straight away, so do not
2155 // schedule the send
2156 return allocateMissBuffer(pkt, curTick(), false);
2157 } else {
2158 // free the request and packet
2159 delete pkt->req;
2160 delete pkt;
2161 }
2162 }
2163 }
2164
2165 return NULL;
2166}
2167
2168bool
2169Cache::isCachedAbove(PacketPtr pkt, bool is_timing) const
2170{
2171 if (!forwardSnoops)
2172 return false;
2173 // Mirroring the flow of HardPFReqs, the cache sends CleanEvict and
2174 // Writeback snoops into upper level caches to check for copies of the
2175 // same block. Using the BLOCK_CACHED flag with the Writeback/CleanEvict
2176 // packet, the cache can inform the crossbar below of presence or absence
2177 // of the block.
2178 if (is_timing) {
2179 Packet snoop_pkt(pkt, true, false);
2180 snoop_pkt.setExpressSnoop();
2181 // Assert that packet is either Writeback or CleanEvict and not a
2182 // prefetch request because prefetch requests need an MSHR and may
2183 // generate a snoop response.
2184 assert(pkt->evictingBlock());
2185 snoop_pkt.senderState = NULL;
2186 cpuSidePort->sendTimingSnoopReq(&snoop_pkt);
2187 // Writeback/CleanEvict snoops do not generate a snoop response.
2188 assert(!(snoop_pkt.memInhibitAsserted()));
2189 return snoop_pkt.isBlockCached();
2190 } else {
2191 cpuSidePort->sendAtomicSnoop(pkt);
2192 return pkt->isBlockCached();
2193 }
2194}
2195
2196PacketPtr
2197Cache::getTimingPacket()
2198{
2199 MSHR *mshr = getNextMSHR();
2200
2201 if (mshr == NULL) {
2202 return NULL;
2203 }
2204
2205 // use request from 1st target
2206 PacketPtr tgt_pkt = mshr->getTarget()->pkt;
2207 PacketPtr pkt = NULL;
2208
2209 DPRINTF(CachePort, "%s %s for addr %#llx size %d\n", __func__,
2210 tgt_pkt->cmdString(), tgt_pkt->getAddr(), tgt_pkt->getSize());
2211
2212 CacheBlk *blk = tags->findBlock(mshr->blkAddr, mshr->isSecure);
2213
2214 if (tgt_pkt->cmd == MemCmd::HardPFReq && forwardSnoops) {
2215 // We need to check the caches above us to verify that
2216 // they don't have a copy of this block in the dirty state
2217 // at the moment. Without this check we could get a stale
2218 // copy from memory that might get used in place of the
2219 // dirty one.
2220 Packet snoop_pkt(tgt_pkt, true, false);
2221 snoop_pkt.setExpressSnoop();
2222 snoop_pkt.senderState = mshr;
2223 cpuSidePort->sendTimingSnoopReq(&snoop_pkt);
2224
2225 // Check to see if the prefetch was squashed by an upper cache (to
2226 // prevent us from grabbing the line) or if a Check to see if a
2227 // writeback arrived between the time the prefetch was placed in
2228 // the MSHRs and when it was selected to be sent or if the
2229 // prefetch was squashed by an upper cache.
2230
2231 // It is important to check memInhibitAsserted before
2232 // prefetchSquashed. If another cache has asserted MEM_INGIBIT, it
2233 // will be sending a response which will arrive at the MSHR
2234 // allocated ofr this request. Checking the prefetchSquash first
2235 // may result in the MSHR being prematurely deallocated.
2236
2237 if (snoop_pkt.memInhibitAsserted()) {
2238 // If we are getting a non-shared response it is dirty
2239 bool pending_dirty_resp = !snoop_pkt.sharedAsserted();
2240 markInService(mshr, pending_dirty_resp);
2241 DPRINTF(Cache, "Upward snoop of prefetch for addr"
2242 " %#x (%s) hit\n",
2243 tgt_pkt->getAddr(), tgt_pkt->isSecure()? "s": "ns");
2244 return NULL;
2245 }
2246
2247 if (snoop_pkt.isBlockCached() || blk != NULL) {
2248 DPRINTF(Cache, "Block present, prefetch squashed by cache. "
2249 "Deallocating mshr target %#x.\n",
2250 mshr->blkAddr);
2251
2252 // Deallocate the mshr target
2253 if (tgt_pkt->cmd != MemCmd::Writeback) {
2254 if (mshr->queue->forceDeallocateTarget(mshr)) {
2255 // Clear block if this deallocation resulted freed an
2256 // mshr when all had previously been utilized
2257 clearBlocked((BlockedCause)(mshr->queue->index));
2258 }
2259 return NULL;
2260 } else {
2261 // If this is a Writeback, and the snoops indicate that the blk
2262 // is cached above, set the BLOCK_CACHED flag in the Writeback
2263 // packet, so that it does not reset the bits corresponding to
2264 // this block in the snoop filter below.
2265 tgt_pkt->setBlockCached();
2266 }
2267 }
2268 }
2269
2270 if (mshr->isForwardNoResponse()) {
2271 // no response expected, just forward packet as it is
2272 assert(tags->findBlock(mshr->blkAddr, mshr->isSecure) == NULL);
2273 pkt = tgt_pkt;
2274 } else {
2275 pkt = getBusPacket(tgt_pkt, blk, mshr->needsExclusive());
2276
2277 mshr->isForward = (pkt == NULL);
2278
2279 if (mshr->isForward) {
2280 // not a cache block request, but a response is expected
2281 // make copy of current packet to forward, keep current
2282 // copy for response handling
2283 pkt = new Packet(tgt_pkt, false, true);
2284 if (pkt->isWrite()) {
2285 pkt->setData(tgt_pkt->getConstPtr<uint8_t>());
2286 }
2287 }
2288 }
2289
2290 assert(pkt != NULL);
2291 pkt->senderState = mshr;
2292 return pkt;
2293}
2294
2295
2296Tick
2297Cache::nextMSHRReadyTime() const
2298{
2299 Tick nextReady = std::min(mshrQueue.nextMSHRReadyTime(),
2300 writeBuffer.nextMSHRReadyTime());
2301
2302 // Don't signal prefetch ready time if no MSHRs available
2303 // Will signal once enoguh MSHRs are deallocated
2304 if (prefetcher && mshrQueue.canPrefetch()) {
2305 nextReady = std::min(nextReady,
2306 prefetcher->nextPrefetchReadyTime());
2307 }
2308
2309 return nextReady;
2310}
2311
2312void
2313Cache::serialize(CheckpointOut &cp) const
2314{
2315 bool dirty(isDirty());
2316
2317 if (dirty) {
2318 warn("*** The cache still contains dirty data. ***\n");
2319 warn(" Make sure to drain the system using the correct flags.\n");
2320 warn(" This checkpoint will not restore correctly and dirty data in "
2321 "the cache will be lost!\n");
2322 }
2323
2324 // Since we don't checkpoint the data in the cache, any dirty data
2325 // will be lost when restoring from a checkpoint of a system that
2326 // wasn't drained properly. Flag the checkpoint as invalid if the
2327 // cache contains dirty data.
2328 bool bad_checkpoint(dirty);
2329 SERIALIZE_SCALAR(bad_checkpoint);
2330}
2331
2332void
2333Cache::unserialize(CheckpointIn &cp)
2334{
2335 bool bad_checkpoint;
2336 UNSERIALIZE_SCALAR(bad_checkpoint);
2337 if (bad_checkpoint) {
2338 fatal("Restoring from checkpoints with dirty caches is not supported "
2339 "in the classic memory system. Please remove any caches or "
2340 " drain them properly before taking checkpoints.\n");
2341 }
2342}
2343
2344///////////////
2345//
2346// CpuSidePort
2347//
2348///////////////
2349
2350AddrRangeList
2351Cache::CpuSidePort::getAddrRanges() const
2352{
2353 return cache->getAddrRanges();
2354}
2355
2356bool
2357Cache::CpuSidePort::recvTimingReq(PacketPtr pkt)
2358{
2359 assert(!cache->system->bypassCaches());
2360
2361 bool success = false;
2362
2363 // always let inhibited requests through, even if blocked,
2364 // ultimately we should check if this is an express snoop, but at
2365 // the moment that flag is only set in the cache itself
2366 if (pkt->memInhibitAsserted()) {
2367 // do not change the current retry state
2368 bool M5_VAR_USED bypass_success = cache->recvTimingReq(pkt);
2369 assert(bypass_success);
2370 return true;
2371 } else if (blocked || mustSendRetry) {
2372 // either already committed to send a retry, or blocked
2373 success = false;
2374 } else {
2375 // pass it on to the cache, and let the cache decide if we
2376 // have to retry or not
2377 success = cache->recvTimingReq(pkt);
2378 }
2379
2380 // remember if we have to retry
2381 mustSendRetry = !success;
2382 return success;
2383}
2384
2385Tick
2386Cache::CpuSidePort::recvAtomic(PacketPtr pkt)
2387{
2388 return cache->recvAtomic(pkt);
2389}
2390
2391void
2392Cache::CpuSidePort::recvFunctional(PacketPtr pkt)
2393{
2394 // functional request
2395 cache->functionalAccess(pkt, true);
2396}
2397
2398Cache::
2399CpuSidePort::CpuSidePort(const std::string &_name, Cache *_cache,
2400 const std::string &_label)
2401 : BaseCache::CacheSlavePort(_name, _cache, _label), cache(_cache)
2402{
2403}
2404
2405Cache*
2406CacheParams::create()
2407{
2408 assert(tags);
2409
2410 return new Cache(this);
2411}
2412///////////////
2413//
2414// MemSidePort
2415//
2416///////////////
2417
2418bool
2419Cache::MemSidePort::recvTimingResp(PacketPtr pkt)
2420{
2421 cache->recvTimingResp(pkt);
2422 return true;
2423}
2424
2425// Express snooping requests to memside port
2426void
2427Cache::MemSidePort::recvTimingSnoopReq(PacketPtr pkt)
2428{
2429 // handle snooping requests
2430 cache->recvTimingSnoopReq(pkt);
2431}
2432
2433Tick
2434Cache::MemSidePort::recvAtomicSnoop(PacketPtr pkt)
2435{
2436 return cache->recvAtomicSnoop(pkt);
2437}
2438
2439void
2440Cache::MemSidePort::recvFunctionalSnoop(PacketPtr pkt)
2441{
2442 // functional snoop (note that in contrast to atomic we don't have
2443 // a specific functionalSnoop method, as they have the same
2444 // behaviour regardless)
2445 cache->functionalAccess(pkt, false);
2446}
2447
2448void
2449Cache::CacheReqPacketQueue::sendDeferredPacket()
2450{
2451 // sanity check
2452 assert(!waitingOnRetry);
2453
2454 // there should never be any deferred request packets in the
2455 // queue, instead we resly on the cache to provide the packets
2456 // from the MSHR queue or write queue
2457 assert(deferredPacketReadyTime() == MaxTick);
2458
2459 // check for request packets (requests & writebacks)
2460 PacketPtr pkt = cache.getTimingPacket();
2461 if (pkt == NULL) {
2462 // can happen if e.g. we attempt a writeback and fail, but
2463 // before the retry, the writeback is eliminated because
2464 // we snoop another cache's ReadEx.
2465 } else {
2466 MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
2467 // in most cases getTimingPacket allocates a new packet, and
2468 // we must delete it unless it is successfully sent
2469 bool delete_pkt = !mshr->isForwardNoResponse();
2470
2471 // let our snoop responses go first if there are responses to
2472 // the same addresses we are about to writeback, note that
2473 // this creates a dependency between requests and snoop
2474 // responses, but that should not be a problem since there is
2475 // a chain already and the key is that the snoop responses can
2476 // sink unconditionally
2477 if (snoopRespQueue.hasAddr(pkt->getAddr())) {
2478 DPRINTF(CachePort, "Waiting for snoop response to be sent\n");
2479 Tick when = snoopRespQueue.deferredPacketReadyTime();
2480 schedSendEvent(when);
2481
2482 if (delete_pkt)
2483 delete pkt;
2484
2485 return;
2486 }
2487
2488
2489 waitingOnRetry = !masterPort.sendTimingReq(pkt);
2490
2491 if (waitingOnRetry) {
2492 DPRINTF(CachePort, "now waiting on a retry\n");
2493 if (delete_pkt) {
2494 // we are awaiting a retry, but we
2495 // delete the packet and will be creating a new packet
2496 // when we get the opportunity
2497 delete pkt;
2498 }
2499 // note that we have now masked any requestBus and
2500 // schedSendEvent (we will wait for a retry before
2501 // doing anything), and this is so even if we do not
2502 // care about this packet and might override it before
2503 // it gets retried
2504 } else {
2505 // As part of the call to sendTimingReq the packet is
2506 // forwarded to all neighbouring caches (and any
2507 // caches above them) as a snoop. The packet is also
2508 // sent to any potential cache below as the
2509 // interconnect is not allowed to buffer the
2510 // packet. Thus at this point we know if any of the
2511 // neighbouring, or the downstream cache is
2512 // responding, and if so, if it is with a dirty line
2513 // or not.
2514 bool pending_dirty_resp = !pkt->sharedAsserted() &&
2515 pkt->memInhibitAsserted();
2516
2517 cache.markInService(mshr, pending_dirty_resp);
2518 }
2519 }
2520
2521 // if we succeeded and are not waiting for a retry, schedule the
2522 // next send considering when the next MSHR is ready, note that
2523 // snoop responses have their own packet queue and thus schedule
2524 // their own events
2525 if (!waitingOnRetry) {
2526 schedSendEvent(cache.nextMSHRReadyTime());
2527 }
2528}
2529
2530Cache::
2531MemSidePort::MemSidePort(const std::string &_name, Cache *_cache,
2532 const std::string &_label)
2533 : BaseCache::CacheMasterPort(_name, _cache, _reqQueue, _snoopRespQueue),
2534 _reqQueue(*_cache, *this, _snoopRespQueue, _label),
2535 _snoopRespQueue(*_cache, *this, _label), cache(_cache)
2536{
2537}