[PATCH v2 22/29] arm_mpam: Add helpers to allocate monitors

James Morse
2025-09-10T20:45:21Z

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@arm.com>
Reviewed-by: Ben Horgan <ben.horgan@arm.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 f536ebbcf94e..cf190f896de1 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -340,6 +340,8 @@ 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 326ba9114d70..81c4c2bfea3d 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -210,6 +210,9 @@ 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;
};

@@ -288,6 +291,38 @@ 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_range(&class->ida_csu_mon, 0, 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_range(&class->ida_mbwu_mon, 0,
+ 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;
--
2.39.5