1/*
2 * Copyright (c) 2011-2016 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

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151 assert(is_express_snoop == cache_responding);
152
153 // determine the destination based on the address
154 PortID master_port_id = findPort(pkt->getAddr());
155
156 // test if the crossbar should be considered occupied for the current
157 // port, and exclude express snoops from the check
158 if (!is_express_snoop && !reqLayers[master_port_id]->tryTiming(src_port)) {
159 DPRINTF(CoherentXBar, "%s: src %s packet %s BUSY\n", __func__,
160 src_port->name(), pkt->print());
161 return false;
162 }
163
164 DPRINTF(CoherentXBar, "%s: src %s packet %s\n", __func__,
165 src_port->name(), pkt->print());
166
167 // store size and command as they might be modified when
168 // forwarding the packet
169 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0;
170 unsigned int pkt_cmd = pkt->cmdToIndex();
171
172 // store the old header delay so we can restore it if needed
173 Tick old_header_delay = pkt->headerDelay;

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188 // broadcasted to our snoopers but the source
189 if (snoopFilter) {
190 // check with the snoop filter where to forward this packet
191 auto sf_res = snoopFilter->lookupRequest(pkt, *src_port);
192 // the time required by a packet to be delivered through
193 // the xbar has to be charged also with to lookup latency
194 // of the snoop filter
195 pkt->headerDelay += sf_res.second * clockPeriod();
196 DPRINTF(CoherentXBar, "%s: src %s packet %s SF size: %i lat: %i\n",
197 __func__, src_port->name(), pkt->print(),
198 sf_res.first.size(), sf_res.second);
199
200 if (pkt->isEviction()) {
201 // for block-evicting packets, i.e. writebacks and
202 // clean evictions, there is no need to snoop up, as
203 // all we do is determine if the block is cached or
204 // not, instead just set it here based on the snoop
205 // filter result
206 if (!sf_res.first.empty())

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229 const bool sink_packet = sinkPacket(pkt);
230
231 // in certain cases the crossbar is responsible for responding
232 bool respond_directly = false;
233 // store the original address as an address mapper could possibly
234 // modify the address upon a sendTimingRequest
235 const Addr addr(pkt->getAddr());
236 if (sink_packet) {
237 DPRINTF(CoherentXBar, "%s: Not forwarding %s\n", __func__,
238 pkt->print());
239 } else {
240 // determine if we are forwarding the packet, or responding to
241 // it
242 if (!pointOfCoherency || pkt->isRead() || pkt->isWrite()) {
243 // if we are passing on, rather than sinking, a packet to
244 // which an upstream cache has committed to responding,
245 // the line was needs writable, and the responding only
246 // had an Owned copy, so we need to immidiately let the

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270 // check if we were successful in sending the packet onwards
271 if (!success) {
272 // express snoops should never be forced to retry
273 assert(!is_express_snoop);
274
275 // restore the header delay
276 pkt->headerDelay = old_header_delay;
277
278 DPRINTF(CoherentXBar, "%s: src %s packet %s RETRY\n", __func__,
279 src_port->name(), pkt->print());
280
281 // update the layer state and schedule an idle event
282 reqLayers[master_port_id]->failedTiming(src_port,
283 clockEdge(Cycles(1)));
284 } else {
285 // express snoops currently bypass the crossbar state entirely
286 if (!is_express_snoop) {
287 // if this particular request will generate a snoop

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356 assert(route_lookup != routeTo.end());
357 const PortID slave_port_id = route_lookup->second;
358 assert(slave_port_id != InvalidPortID);
359 assert(slave_port_id < respLayers.size());
360
361 // test if the crossbar should be considered occupied for the
362 // current port
363 if (!respLayers[slave_port_id]->tryTiming(src_port)) {
364 DPRINTF(CoherentXBar, "%s: src %s packet %s BUSY\n", __func__,
365 src_port->name(), pkt->print());
366 return false;
367 }
368
369 DPRINTF(CoherentXBar, "%s: src %s packet %s\n", __func__,
370 src_port->name(), pkt->print());
371
372 // store size and command as they might be modified when
373 // forwarding the packet
374 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0;
375 unsigned int pkt_cmd = pkt->cmdToIndex();
376
377 // a response sees the response latency
378 Tick xbar_delay = responseLatency * clockPeriod();

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405 transDist[pkt_cmd]++;
406
407 return true;
408}
409
410void
411CoherentXBar::recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id)
412{
413 DPRINTF(CoherentXBar, "%s: src %s packet %s\n", __func__,
414 masterPorts[master_port_id]->name(), pkt->print());
415
416 // update stats here as we know the forwarding will succeed
417 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0;
418 transDist[pkt->cmdToIndex()]++;
419 snoops++;
420 snoopTraffic += pkt_size;
421
422 // we should only see express snoops from caches

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434
435 if (snoopFilter) {
436 // let the Snoop Filter work its magic and guide probing
437 auto sf_res = snoopFilter->lookupSnoop(pkt);
438 // the time required by a packet to be delivered through
439 // the xbar has to be charged also with to lookup latency
440 // of the snoop filter
441 pkt->headerDelay += sf_res.second * clockPeriod();
442 DPRINTF(CoherentXBar, "%s: src %s packet %s SF size: %i lat: %i\n",
443 __func__, masterPorts[master_port_id]->name(), pkt->print(),
444 sf_res.first.size(), sf_res.second);
445
446 // forward to all snoopers
447 forwardTiming(pkt, InvalidPortID, sf_res.first);
448 } else {
449 forwardTiming(pkt, InvalidPortID);
450 }
451
452 // add the snoop delay to our header delay, and then reset it

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488
489 // test if the crossbar should be considered occupied for the
490 // current port, note that the check is bypassed if the response
491 // is being passed on as a normal response since this is occupying
492 // the response layer rather than the snoop response layer
493 if (forwardAsSnoop) {
494 assert(dest_port_id < snoopLayers.size());
495 if (!snoopLayers[dest_port_id]->tryTiming(src_port)) {
496 DPRINTF(CoherentXBar, "%s: src %s packet %s BUSY\n", __func__,
497 src_port->name(), pkt->print());
498 return false;
499 }
500 } else {
501 // get the master port that mirrors this slave port internally
502 MasterPort* snoop_port = snoopRespPorts[slave_port_id];
503 assert(dest_port_id < respLayers.size());
504 if (!respLayers[dest_port_id]->tryTiming(snoop_port)) {
505 DPRINTF(CoherentXBar, "%s: src %s packet %s BUSY\n", __func__,
506 snoop_port->name(), pkt->print());
507 return false;
508 }
509 }
510
511 DPRINTF(CoherentXBar, "%s: src %s packet %s\n", __func__,
512 src_port->name(), pkt->print());
513
514 // store size and command as they might be modified when
515 // forwarding the packet
516 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0;
517 unsigned int pkt_cmd = pkt->cmdToIndex();
518
519 // responses are never express snoops
520 assert(!pkt->isExpressSnoop());

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563 assert(slave_port_id != dest_port_id);
564
565 if (snoopFilter) {
566 // update the probe filter so that it can properly track the line
567 snoopFilter->updateSnoopResponse(pkt, *slavePorts[slave_port_id],
568 *slavePorts[dest_port_id]);
569 }
570
571 DPRINTF(CoherentXBar, "%s: src %s packet %s FWD RESP\n", __func__,
572 src_port->name(), pkt->print());
573
574 // as a normal response, it should go back to a master through
575 // one of our slave ports, we also pay for any outstanding
576 // header latency
577 Tick latency = pkt->headerDelay;
578 pkt->headerDelay = 0;
579 slavePorts[dest_port_id]->schedTimingResp(pkt, curTick() + latency);
580

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592 return true;
593}
594
595
596void
597CoherentXBar::forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id,
598 const std::vector<QueuedSlavePort*>& dests)
599{
600 DPRINTF(CoherentXBar, "%s for %s\n", __func__, pkt->print());
601
602 // snoops should only happen if the system isn't bypassing caches
603 assert(!system->bypassCaches());
604
605 unsigned fanout = 0;
606
607 for (const auto& p: dests) {
608 // we could have gotten this request from a snooping master

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628 // so the retry will always be coming from a port to which we
629 // tried to forward a request
630 reqLayers[master_port_id]->recvRetry();
631}
632
633Tick
634CoherentXBar::recvAtomic(PacketPtr pkt, PortID slave_port_id)
635{
636 DPRINTF(CoherentXBar, "%s: src %s packet %s\n", __func__,
637 slavePorts[slave_port_id]->name(), pkt->print());
638
639 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0;
640 unsigned int pkt_cmd = pkt->cmdToIndex();
641
642 MemCmd snoop_response_cmd = MemCmd::InvalidCmd;
643 Tick snoop_response_latency = 0;
644
645 if (!system->bypassCaches()) {
646 // forward to all snoopers but the source
647 std::pair<MemCmd, Tick> snoop_result;
648 if (snoopFilter) {
649 // check with the snoop filter where to forward this packet
650 auto sf_res =
651 snoopFilter->lookupRequest(pkt, *slavePorts[slave_port_id]);
652 snoop_response_latency += sf_res.second * clockPeriod();
653 DPRINTF(CoherentXBar, "%s: src %s packet %s SF size: %i lat: %i\n",
654 __func__, slavePorts[slave_port_id]->name(), pkt->print(),
655 sf_res.first.size(), sf_res.second);
656
657 // let the snoop filter know about the success of the send
658 // operation, and do it even before sending it onwards to
659 // avoid situations where atomic upward snoops sneak in
660 // between and change the filter state
661 snoopFilter->finishRequest(false, pkt->getAddr(), pkt->isSecure());
662
663 snoop_result = forwardAtomic(pkt, slave_port_id, InvalidPortID,

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674
675 const bool sink_packet = sinkPacket(pkt);
676
677 // even if we had a snoop response, we must continue and also
678 // perform the actual request at the destination
679 PortID master_port_id = findPort(pkt->getAddr());
680
681 if (sink_packet) {
682 DPRINTF(CoherentXBar, "%s: Not forwarding %s\n", __func__,
683 pkt->print());
684 } else {
685 if (!pointOfCoherency || pkt->isRead() || pkt->isWrite()) {
686 // forward the request to the appropriate destination
687 response_latency = masterPorts[master_port_id]->sendAtomic(pkt);
688 } else {
689 // if it does not need a response we sink the packet above
690 assert(pkt->needsResponse());
691

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726 // @todo: Not setting header time
727 pkt->payloadDelay = response_latency;
728 return response_latency;
729}
730
731Tick
732CoherentXBar::recvAtomicSnoop(PacketPtr pkt, PortID master_port_id)
733{
734 DPRINTF(CoherentXBar, "%s: src %s packet %s\n", __func__,
735 masterPorts[master_port_id]->name(), pkt->print());
736
737 // add the request snoop data
738 unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0;
739 snoops++;
740 snoopTraffic += pkt_size;
741
742 // forward to all snoopers
743 std::pair<MemCmd, Tick> snoop_result;
744 Tick snoop_response_latency = 0;
745 if (snoopFilter) {
746 auto sf_res = snoopFilter->lookupSnoop(pkt);
747 snoop_response_latency += sf_res.second * clockPeriod();
748 DPRINTF(CoherentXBar, "%s: src %s packet %s SF size: %i lat: %i\n",
749 __func__, masterPorts[master_port_id]->name(), pkt->print(),
750 sf_res.first.size(), sf_res.second);
751 snoop_result = forwardAtomic(pkt, InvalidPortID, master_port_id,
752 sf_res.first);
753 } else {
754 snoop_result = forwardAtomic(pkt, InvalidPortID);
755 }
756 MemCmd snoop_response_cmd = snoop_result.first;
757 snoop_response_latency += snoop_result.second;
758

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840 return std::make_pair(snoop_response_cmd, snoop_response_latency);
841}
842
843void
844CoherentXBar::recvFunctional(PacketPtr pkt, PortID slave_port_id)
845{
846 if (!pkt->isPrint()) {
847 // don't do DPRINTFs on PrintReq as it clutters up the output
848 DPRINTF(CoherentXBar, "%s: src %s packet %s\n", __func__,
849 slavePorts[slave_port_id]->name(), pkt->print());
850 }
851
852 if (!system->bypassCaches()) {
853 // forward to all snoopers but the source
854 forwardFunctional(pkt, slave_port_id);
855 }
856
857 // there is no need to continue if the snooping has found what we

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875 }
876}
877
878void
879CoherentXBar::recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id)
880{
881 if (!pkt->isPrint()) {
882 // don't do DPRINTFs on PrintReq as it clutters up the output
883 DPRINTF(CoherentXBar, "%s: src %s packet %s\n", __func__,
884 masterPorts[master_port_id]->name(), pkt->print());
885 }
886
887 for (const auto& p : slavePorts) {
888 if (p->checkFunctional(pkt)) {
889 if (pkt->needsResponse())
890 pkt->makeResponse();
891 return;
892 }

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