linux-kernel - [RFC PATCH 12/38] arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks

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Message-Id: <20251205215901.17772-13-james.morse@arm.com>
Date: Fri,  5 Dec 2025 21:58:35 +0000
From: James Morse <james.morse@....com>
To: linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.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@...nel.org>,
	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>,
	Gavin Shan <gshan@...hat.com>,
	Ben Horgan <ben.horgan@....com>,
	rohit.mathew@....com,
	reinette.chatre@...el.com,
	Punit Agrawal <punit.agrawal@....qualcomm.com>
Subject: [RFC PATCH 12/38] arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks

arm64 provides helpers for changing a tasks and a cpus mpam partid/pmg
values.

These are used to back a number of resctrl_arch_ functions. Connect them
up.

Signed-off-by: James Morse <james.morse@....com>
---
 drivers/resctrl/mpam_resctrl.c | 58 ++++++++++++++++++++++++++++++++++
 include/linux/arm_mpam.h       |  5 +++
 2 files changed, 63 insertions(+)

diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index ae0d17857b78..c2650abb99ec 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -8,6 +8,7 @@
 #include <linux/cpu.h>
 #include <linux/cpumask.h>
 #include <linux/errno.h>
+#include <linux/limits.h>
 #include <linux/list.h>
 #include <linux/printk.h>
 #include <linux/rculist.h>
@@ -32,6 +33,8 @@ static DEFINE_MUTEX(domain_list_lock);
 static bool exposed_alloc_capable;
 static bool exposed_mon_capable;
 
+static bool cdp_enabled;
+
 bool resctrl_arch_alloc_capable(void)
 {
 	return exposed_alloc_capable;
@@ -52,6 +55,61 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *ignored)
 	return mpam_partid_max + 1;
 }
 
+void resctrl_arch_sched_in(struct task_struct *tsk)
+{
+	lockdep_assert_preemption_disabled();
+
+	mpam_thread_switch(tsk);
+}
+
+void resctrl_arch_set_cpu_default_closid_rmid(int cpu, u32 closid, u32 rmid)
+{
+	WARN_ON_ONCE(closid > U16_MAX);
+	WARN_ON_ONCE(rmid > U8_MAX);
+
+	if (!cdp_enabled) {
+		mpam_set_cpu_defaults(cpu, closid, closid, rmid, rmid);
+	} else {
+		/*
+		 * When CDP is enabled, resctrl halves the closid range and we
+		 * use odd/even partid for one closid.
+		 */
+		u32 partid_d = resctrl_get_config_index(closid, CDP_DATA);
+		u32 partid_i = resctrl_get_config_index(closid, CDP_CODE);
+
+		mpam_set_cpu_defaults(cpu, partid_d, partid_i, rmid, rmid);
+	}
+}
+
+void resctrl_arch_sync_cpu_closid_rmid(void *info)
+{
+	struct resctrl_cpu_defaults *r = info;
+
+	lockdep_assert_preemption_disabled();
+
+	if (r) {
+		resctrl_arch_set_cpu_default_closid_rmid(smp_processor_id(),
+							 r->closid, r->rmid);
+	}
+
+	resctrl_arch_sched_in(current);
+}
+
+void resctrl_arch_set_closid_rmid(struct task_struct *tsk, u32 closid, u32 rmid)
+{
+	WARN_ON_ONCE(closid > U16_MAX);
+	WARN_ON_ONCE(rmid > U8_MAX);
+
+	if (!cdp_enabled) {
+		mpam_set_task_partid_pmg(tsk, closid, closid, rmid, rmid);
+	} else {
+		u32 partid_d = resctrl_get_config_index(closid, CDP_DATA);
+		u32 partid_i = resctrl_get_config_index(closid, CDP_CODE);
+
+		mpam_set_task_partid_pmg(tsk, partid_d, partid_i, rmid, rmid);
+	}
+}
+
 struct rdt_resource *resctrl_arch_get_resource(enum resctrl_res_level l)
 {
 	if (l >= RDT_NUM_RESOURCES)
diff --git a/include/linux/arm_mpam.h b/include/linux/arm_mpam.h
index 2c7d1413a401..5a78299ec464 100644
--- a/include/linux/arm_mpam.h
+++ b/include/linux/arm_mpam.h
@@ -52,6 +52,11 @@ static inline int mpam_ris_create(struct mpam_msc *msc, u8 ris_idx,
 bool resctrl_arch_alloc_capable(void);
 bool resctrl_arch_mon_capable(void);
 
+void resctrl_arch_set_cpu_default_closid(int cpu, u32 closid);
+void resctrl_arch_set_closid_rmid(struct task_struct *tsk, u32 closid, u32 rmid);
+void resctrl_arch_set_cpu_default_closid_rmid(int cpu, u32 closid, u32 rmid);
+void resctrl_arch_sched_in(struct task_struct *tsk);
+
 /**
  * mpam_register_requestor() - Register a requestor with the MPAM driver
  * @partid_max:		The maximum PARTID value the requestor can generate.
-- 
2.39.5