linux-kernel - [PATCH v3 22/29] arm_mpam: Add helpers to allocate monitors

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Message-Id: <20251017185645.26604-23-james.morse@arm.com>
Date: Fri, 17 Oct 2025 18:56:38 +0000
From: James Morse <james.morse@....com>
To: linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-acpi@...r.kernel.org
Cc: James Morse <james.morse@....com>,
	D Scott Phillips OS <scott@...amperecomputing.com>,
	carl@...amperecomputing.com,
	lcherian@...vell.com,
	bobo.shaobowang@...wei.com,
	tan.shaopeng@...itsu.com,
	baolin.wang@...ux.alibaba.com,
	Jamie Iles <quic_jiles@...cinc.com>,
	Xin Hao <xhao@...ux.alibaba.com>,
	peternewman@...gle.com,
	dfustini@...libre.com,
	amitsinght@...vell.com,
	David Hildenbrand <david@...hat.com>,
	Dave Martin <dave.martin@....com>,
	Koba Ko <kobak@...dia.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	fenghuay@...dia.com,
	baisheng.gao@...soc.com,
	Jonathan Cameron <jonathan.cameron@...wei.com>,
	Rob Herring <robh@...nel.org>,
	Rohit Mathew <rohit.mathew@....com>,
	Rafael Wysocki <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Hanjun Guo <guohanjun@...wei.com>,
	Sudeep Holla <sudeep.holla@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Danilo Krummrich <dakr@...nel.org>,
	Jeremy Linton <jeremy.linton@....com>,
	Gavin Shan <gshan@...hat.com>,
	Ben Horgan <ben.horgan@....com>
Subject: [PATCH v3 22/29] arm_mpam: Add helpers to allocate monitors

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>
---
Changes since v2:
 * Use ida_alloc_max() instead of ida_alloc_range().
---
 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 19cc87aba51a..a29f97cd176a 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -350,6 +350,8 @@ 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 00edee9ebc6c..96a02ea95583 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -197,6 +197,9 @@ 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;
 };
 
@@ -275,6 +278,38 @@ 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;
-- 
2.39.5