[PATCH v3 20/47] arm_mpam: resctrl: Add plumbing against arm64 task and cpu hooks

Ben Horgan
2026-01-12T17:01:40Z

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

arm64 provides helpers for changing a task's and a cpu's mpam partid/pmg
values.

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

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
---
Changes since v2:
apostrophes in commit message
---
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 5b73fe45b8fa..c596b224c967 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>
@@ -37,6 +38,8 @@ 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;
@@ -57,6 +60,61 @@ 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.
--
2.43.0