From f20ac07dded0702b078449a885ed428c70501dff Mon Sep 17 00:00:00 2001
From: Hristo Belchev <hristo.belchev@arm.com>
Date: Mon, 12 Feb 2024 11:54:33 +0000
Subject: [PATCH 1/2] mem: Fix assertions in LRG Q policy

Fix assertions in LRG Queue Policy to correctly assert requestor and
list validity

Change-Id: I84e3f5b8936b74e7ac675faf7a3e6b9999026781
---
 src/mem/qos/q_policy.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/mem/qos/q_policy.cc b/src/mem/qos/q_policy.cc
index a6d13feb7e..9550eb47c6 100644
--- a/src/mem/qos/q_policy.cc
+++ b/src/mem/qos/q_policy.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018 ARM Limited
+ * Copyright (c) 2018,2024 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -91,10 +91,10 @@ LrgQueuePolicy::selectPacket(PacketQueue* q)
                      "from queue with id %d\n", requestor_id);
 
         // Check if this is a known requestor.
-        panic_if(memCtrl->hasRequestor(requestor_id),
+        panic_if(!memCtrl->hasRequestor(requestor_id),
                  "%s: Unrecognized Requestor\n", __func__);
 
-        panic_if(toServe.size() > 0,
+        panic_if(toServe.size() <= 0,
                  "%s: toServe list is empty\n", __func__);
 
         if (toServe.front() == requestor_id) {

From 2138a4ec92c59dd72d9e7a93a6ab17d5eb63236b Mon Sep 17 00:00:00 2001
From: Hristo Belchev <hristo.belchev@arm.com>
Date: Mon, 12 Feb 2024 15:04:58 +0000
Subject: [PATCH 2/2] mem: Fix LIFO q_policy and add assetions

* Fix selectPacket() in LIFO Queue Policy to correctly return the end of
  the `deque` backing store for its packet queue
* Move selectPacket() implementations for FIFO and LIFO queues into
  `q_policy.cc` file

Change-Id: I8c35e5fc83dc380b19f52be14c18b1f414f9e141
---
 src/mem/qos/q_policy.cc | 21 +++++++++++++++++++--
 src/mem/qos/q_policy.hh | 20 +++++++-------------
 2 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/src/mem/qos/q_policy.cc b/src/mem/qos/q_policy.cc
index 9550eb47c6..0a210f3c71 100644
--- a/src/mem/qos/q_policy.cc
+++ b/src/mem/qos/q_policy.cc
@@ -69,9 +69,27 @@ QueuePolicy::create(const QoSMemCtrlParams &p)
     }
 }
 
+QueuePolicy::PacketQueue::iterator
+FifoQueuePolicy::selectPacket(PacketQueue* queue)
+{
+    panic_if(queue->empty(),
+             "Provided packet queue is not usable by queue policy");
+    return queue->begin();
+}
+
+QueuePolicy::PacketQueue::iterator
+LifoQueuePolicy::selectPacket(PacketQueue* queue)
+{
+    panic_if(queue->empty(),
+             "Provided packet queue is not usable by queue policy");
+    return std::prev(queue->end());
+}
+
 QueuePolicy::PacketQueue::iterator
 LrgQueuePolicy::selectPacket(PacketQueue* q)
 {
+    panic_if(q->empty(),
+             "Provided packet queue is not usable by queue policy");
     QueuePolicy::PacketQueue::iterator ret = q->end();
 
     // Tracks one packet per requestor in the queue
@@ -137,8 +155,7 @@ LrgQueuePolicy::selectPacket(PacketQueue* q)
 
     DPRINTF(QOS, "QoSQPolicy::lrg no packet was serviced\n");
 
-    // Ret will be : packet to serve if any found or queue begin
-    // (end if queue is empty)
+    // Ret will be : packet to serve
     return ret;
 }
 
diff --git a/src/mem/qos/q_policy.hh b/src/mem/qos/q_policy.hh
index fc9200d0af..39fd2d9bb4 100644
--- a/src/mem/qos/q_policy.hh
+++ b/src/mem/qos/q_policy.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018 ARM Limited
+ * Copyright (c) 2018, 2024 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -93,7 +93,7 @@ class QueuePolicy
      * The implementation of this virtual method selects the packet
      * to be serviced from the packet queue passed as an argument.
      *
-     * @param queue Packet queue
+     * @param queue Non-empty packet queue to select a packet from
      * @return Iterator pointing to the packet in the queue to be
      *         serviced
      */
@@ -127,14 +127,11 @@ class LifoQueuePolicy : public QueuePolicy
     /**
      * Implements LIFO packet select policy
      *
-     * @param queue The queue in which to select a packet
+     * @param queue The non-empty queue from which to select a packet
      * @return Iterator to the selected packet
      */
     PacketQueue::iterator
-    selectPacket(PacketQueue* queue) override
-    {
-        return queue->end();
-    }
+    selectPacket(PacketQueue* queue) override;
 };
 
 /** First In First Out Queue Policy */
@@ -148,14 +145,11 @@ class FifoQueuePolicy : public QueuePolicy
     /**
      * Implements FCFS packet select policy
      *
-     * @param queue The queue in which to select a packet
+     * @param queue The non-empty queue from which to select a packet
      * @return Iterator to the selected packet
      */
     PacketQueue::iterator
-    selectPacket(PacketQueue* queue) override
-    {
-        return queue->begin();
-    }
+    selectPacket(PacketQueue* queue) override;
 };
 
 /**
@@ -176,7 +170,7 @@ class LrgQueuePolicy : public QueuePolicy
     /**
      * Implements LRG packet select policy
      *
-     * @param queue The queue in which to select a packet
+     * @param queue The non-empty queue from which to select a packet
      * @return Iterator to the selected packet
      */
     PacketQueue::iterator