linux-kernel - [PATCH 25/33] arm_mpam: Add helpers to allocate monitors

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Message-ID: <20251107123450.664001-26-ben.horgan@arm.com>
Date: Fri,  7 Nov 2025 12:34:42 +0000
From: Ben Horgan <ben.horgan@....com>
To: james.morse@....com
Cc: amitsinght@...vell.com,
	baisheng.gao@...soc.com,
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	Ben Horgan <ben.horgan@....com>,
	Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Subject: [PATCH 25/33] arm_mpam: Add helpers to allocate monitors

From: James Morse <james.morse@....com>

MPAM's MSC support a number of monitors, each of which supports
bandwidth counters, or cache-storage-utilisation counters. To use
a counter, a monitor needs to be configured. Add helpers to allocate
and free CSU or MBWU monitors.

Signed-off-by: James Morse <james.morse@....com>
Reviewed-by: Ben Horgan <ben.horgan@....com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>
Tested-by: Fenghua Yu <fenghuay@...dia.com>
Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Tested-by: Peter Newman <peternewman@...gle.com>
Signed-off-by: Ben Horgan <ben.horgan@....com>
---
 drivers/resctrl/mpam_devices.c  |  2 ++
 drivers/resctrl/mpam_internal.h | 35 +++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 22b8e41a346b..f51ffb1400db 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -412,6 +412,8 @@ mpam_class_alloc(u8 level_idx, enum mpam_class_types type)
 	class->level = level_idx;
 	class->type = type;
 	INIT_LIST_HEAD_RCU(&class->classes_list);
+	ida_init(&class->ida_csu_mon);
+	ida_init(&class->ida_mbwu_mon);
 
 	list_add_rcu(&class->classes_list, &mpam_classes);
 
diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index b947f30fbf14..e59c0f4d9ada 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -198,6 +198,9 @@ struct mpam_class {
 	/* member of mpam_classes */
 	struct list_head	classes_list;
 
+	struct ida		ida_csu_mon;
+	struct ida		ida_mbwu_mon;
+
 	struct mpam_garbage	garbage;
 };
 
@@ -277,6 +280,38 @@ struct mpam_msc_ris {
 	struct mpam_garbage	garbage;
 };
 
+static inline int mpam_alloc_csu_mon(struct mpam_class *class)
+{
+	struct mpam_props *cprops = &class->props;
+
+	if (!mpam_has_feature(mpam_feat_msmon_csu, cprops))
+		return -EOPNOTSUPP;
+
+	return ida_alloc_max(&class->ida_csu_mon, cprops->num_csu_mon - 1,
+			     GFP_KERNEL);
+}
+
+static inline void mpam_free_csu_mon(struct mpam_class *class, int csu_mon)
+{
+	ida_free(&class->ida_csu_mon, csu_mon);
+}
+
+static inline int mpam_alloc_mbwu_mon(struct mpam_class *class)
+{
+	struct mpam_props *cprops = &class->props;
+
+	if (!mpam_has_feature(mpam_feat_msmon_mbwu, cprops))
+		return -EOPNOTSUPP;
+
+	return ida_alloc_max(&class->ida_mbwu_mon, cprops->num_mbwu_mon - 1,
+			     GFP_KERNEL);
+}
+
+static inline void mpam_free_mbwu_mon(struct mpam_class *class, int mbwu_mon)
+{
+	ida_free(&class->ida_mbwu_mon, mbwu_mon);
+}
+
 /* List of all classes - protected by srcu*/
 extern struct srcu_struct mpam_srcu;
 extern struct list_head mpam_classes;
-- 
2.43.0