[PATCH RFC v2 04/19] resctrl: Add node-scope MBM total event

[Fenghua Yu <fenghuay@nvidia.com>]

Some MPAM systems count total memory bandwidth on a memory-side MSC that
is scoped to a NUMA node rather than the L3 cache. Add a new
QOS_NODE_MBM_TOTAL_EVENT_ID event for this node-scoped total, backed by
the MBA resource, and register it in the mon_event_all[] table.

Keep the new event id contiguous with the existing L3 MBM events so the
for_each_mbm_event_id() range and the per-domain software MBM state
arrays continue to be sized from the first to the last MBM event. Extend
resctrl_is_mbm_event() to recognise it, and add helpers
resctrl_is_mbm_total_event() and resctrl_mbm_total_event_id() so callers
can select the node-scoped total when it is enabled and fall back to the
L3 total otherwise.

Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>
---
 fs/resctrl/monitor.c          |  2 ++
 include/linux/resctrl.h       | 27 +++++++++++++++++++++++----
 include/linux/resctrl_types.h | 15 ++++++++++++++-
 3 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 5865a509174c..ea9d92b6b581 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -1040,6 +1040,8 @@ struct mon_evt mon_event_all[QOS_NUM_EVENTS] = {
 	MON_EVENT(QOS_L3_OCCUP_EVENT_ID,		"llc_occupancy",	RDT_RESOURCE_L3,	false),
 	MON_EVENT(QOS_L3_MBM_TOTAL_EVENT_ID,		"mbm_total_bytes",	RDT_RESOURCE_L3,	false),
 	MON_EVENT(QOS_L3_MBM_LOCAL_EVENT_ID,		"mbm_local_bytes",	RDT_RESOURCE_L3,	false),
+	MON_EVENT(QOS_NODE_MBM_TOTAL_EVENT_ID,		"mbm_total_bytes",
+		  RDT_RESOURCE_MBA,			false),
 	MON_EVENT(PMT_EVENT_ENERGY,			"core_energy",		RDT_RESOURCE_PERF_PKG,	true),
 	MON_EVENT(PMT_EVENT_ACTIVITY,			"activity",		RDT_RESOURCE_PERF_PKG,	true),
 	MON_EVENT(PMT_EVENT_STALLS_LLC_HIT,		"stalls_llc_hit",	RDT_RESOURCE_PERF_PKG,	false),
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index f2c3621b006e..195c0948b26d 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -633,16 +633,35 @@ bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
 
 static inline bool resctrl_is_mbm_event(enum resctrl_event_id eventid)
 {
-	return (eventid >= QOS_L3_MBM_TOTAL_EVENT_ID &&
-		eventid <= QOS_L3_MBM_LOCAL_EVENT_ID);
+	return ((eventid >= QOS_L3_MBM_TOTAL_EVENT_ID &&
+		 eventid <= QOS_L3_MBM_LOCAL_EVENT_ID) ||
+		eventid == QOS_NODE_MBM_TOTAL_EVENT_ID);
+}
+
+static inline bool resctrl_is_mbm_total_event(enum resctrl_event_id eventid)
+{
+	return eventid == QOS_L3_MBM_TOTAL_EVENT_ID ||
+	       eventid == QOS_NODE_MBM_TOTAL_EVENT_ID;
+}
+
+static inline enum resctrl_event_id resctrl_mbm_total_event_id(void)
+{
+	if (resctrl_is_mon_event_enabled(QOS_NODE_MBM_TOTAL_EVENT_ID))
+		return QOS_NODE_MBM_TOTAL_EVENT_ID;
+
+	return QOS_L3_MBM_TOTAL_EVENT_ID;
 }
 
 u32 resctrl_get_mon_evt_cfg(enum resctrl_event_id eventid);
 
-/* Iterate over all memory bandwidth events */
+/*
+ * Iterate over all memory bandwidth events. The node-scope total event is
+ * contiguous with the L3 events, so it is covered by the same range. Loop
+ * bodies must skip events that are not enabled.
+ */
 #define for_each_mbm_event_id(eventid)				\
 	for (eventid = QOS_L3_MBM_TOTAL_EVENT_ID;		\
-	     eventid <= QOS_L3_MBM_LOCAL_EVENT_ID; eventid++)
+	     eventid <= QOS_NODE_MBM_TOTAL_EVENT_ID; eventid++)
 
 /* Iterate over memory bandwidth arrays in domain structures */
 #define for_each_mbm_idx(idx)					\
diff --git a/include/linux/resctrl_types.h b/include/linux/resctrl_types.h
index a5f56faa18d2..996ae8763b0a 100644
--- a/include/linux/resctrl_types.h
+++ b/include/linux/resctrl_types.h
@@ -50,6 +50,13 @@ enum resctrl_event_id {
 	QOS_L3_MBM_TOTAL_EVENT_ID	= 0x02,
 	QOS_L3_MBM_LOCAL_EVENT_ID	= 0x03,
 
+	/*
+	 * Total memory bandwidth counted on a NUMA node scope MSC (e.g. a
+	 * memory-side MSC above the L3). Kept contiguous with the other MPAM
+	 * events so arch code can size per-event arrays by the last MPAM event.
+	 */
+	QOS_NODE_MBM_TOTAL_EVENT_ID	= 0x04,
+
 	/* Intel Telemetry Events */
 	PMT_EVENT_ENERGY,
 	PMT_EVENT_ACTIVITY,
@@ -65,7 +72,13 @@ enum resctrl_event_id {
 	QOS_NUM_EVENTS,
 };
 
-#define QOS_NUM_L3_MBM_EVENTS	(QOS_L3_MBM_LOCAL_EVENT_ID - QOS_L3_MBM_TOTAL_EVENT_ID + 1)
+/*
+ * Number of software MBM state slots per monitoring domain. The MBM events
+ * (L3 total, L3 local and the node-scope total) are contiguous, so the last
+ * one bounds the array. The node-scope total event is only ever enabled on
+ * Arm/MPAM; on x86 its slot is simply left unused.
+ */
+#define QOS_NUM_L3_MBM_EVENTS	(QOS_NODE_MBM_TOTAL_EVENT_ID - QOS_L3_MBM_TOTAL_EVENT_ID + 1)
 #define MBM_STATE_IDX(evt)	((evt) - QOS_L3_MBM_TOTAL_EVENT_ID)
 
 #endif /* __LINUX_RESCTRL_TYPES_H */
-- 
2.53.0