mem: Allow CMOs as snooping requests in the snoop filter

The snoop filter performs sanity checks of the type of packets that
are expected to snoop caches above. Cache maintenace operations are
expected to perform a clean and or invalidate on all caches down to
the specified point of reference and therefore could also generate
snoops.

Change-Id: I7f8fef246a85faa87ccd289c28b49686ed7caa08
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
Reviewed-by: Anouk Van Laer <anouk.vanlaer@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5052
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

diff --git a/src/mem/snoop_filter.cc b/src/mem/snoop_filter.cc
index b372cfe2142691aec6b8ac45ac48628a357ff252..252fbb5245af81d442b3a657aa01e8f8a28690ef 100755 (executable)
--- a/src/mem/snoop_filter.cc
+++ b/src/mem/snoop_filter.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2016 ARM Limited
+ * Copyright (c) 2013-2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -215,10 +215,13 @@ SnoopFilter::lookupSnoop(const Packet* cpkt)
     // ReadEx and Writes require both invalidation and exlusivity, while reads
     // require neither. Writebacks on the other hand require exclusivity but
     // not the invalidation. Previously Writebacks did not generate upward
-    // snoops so this was never an aissue. Now that Writebacks generate snoops
-    // we need to special case for Writebacks.
+    // snoops so this was never an issue. Now that Writebacks generate snoops
+    // we need a special case for Writebacks. Additionally cache maintenance
+    // operations can generate snoops as they clean and/or invalidate all
+    // caches down to the specified point of reference.
     assert(cpkt->isWriteback() || cpkt->req->isUncacheable() ||
-           (cpkt->isInvalidate() == cpkt->needsWritable()));
+           (cpkt->isInvalidate() == cpkt->needsWritable()) ||
+           cpkt->req->isCacheMaintenance());
     if (cpkt->isInvalidate() && !sf_item.requested) {
         // Early clear of the holder, if no other request is currently going on
         // @todo: This should possibly be updated even though we do not filter