[PATCH v8 next 10/10] arm_mpam: Add mpam_sync_config() for dynamic rmid expansion

Zeng Heng
2026-04-13T08:54:59Z

Add mpam_sync_config() to synchronize configuration when dynamically
expanding rmid resources. When binding a new reqpartid to a control group,
the driver maps the reqpartid to the corresponding intpartid or applies
the control group's existing configuration to new partid if without
Narrow-PARTID feature.

Extend mpam_apply_config() with the 'sync' work mode:
* Sync mode: mpam_sync_config() calls this to apply existing
configuration without updating config.
* Update (non-sync) mode: resctrl_arch_update_one() calls this to
compare, update, and apply configuration. This mode retains the
original behavior.

Signed-off-by: Zeng Heng <zengheng4@huawei.com>
---
drivers/resctrl/mpam_devices.c | 23 ++++++++++++++++++-----
drivers/resctrl/mpam_internal.h | 2 +-
drivers/resctrl/mpam_resctrl.c | 29 ++++++++++++++++++++++++++---
3 files changed, 45 insertions(+), 9 deletions(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index cf94b45b4f9e..47345b8add3c 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -1762,6 +1762,7 @@ struct mpam_write_config_arg {
struct mpam_msc_ris *ris;
struct mpam_component *comp;
u16 partid;
+ bool sync;
};

static int __write_config(void *arg)
@@ -1770,6 +1771,15 @@ static int __write_config(void *arg)
struct mpam_write_config_arg *c = arg;
u32 reqpartid;

+ if (c->sync) {
+ /* c->partid should be within the range of reqPARTIDs */
+ WARN_ON_ONCE(c->partid < closid_num);
+
+ mpam_reprogram_ris_partid(c->ris, c->partid,
+ &c->comp->cfg[req2intpartid(c->partid)]);
+ return 0;
+ }
+
/* c->partid should be within the range of intPARTIDs */
WARN_ON_ONCE(c->partid >= closid_num);

@@ -2942,7 +2952,7 @@ static bool mpam_update_config(struct mpam_config *cfg,
}

int mpam_apply_config(struct mpam_component *comp, u16 partid,
- struct mpam_config *cfg)
+ struct mpam_config *cfg, bool sync)
{
struct mpam_write_config_arg arg;
struct mpam_msc_ris *ris;
@@ -2951,14 +2961,17 @@ int mpam_apply_config(struct mpam_component *comp, u16 partid,

lockdep_assert_cpus_held();

- /* Don't pass in the current config! */
- WARN_ON_ONCE(&comp->cfg[partid] == cfg);
+ if (!sync) {
+ /* The partid is within the range of intPARTIDs */
+ WARN_ON_ONCE(partid >= resctrl_arch_get_num_closid(NULL));

- if (!mpam_update_config(&comp->cfg[partid], cfg))
- return 0;
+ if (!mpam_update_config(&comp->cfg[partid], cfg))
+ return 0;
+ }

arg.comp = comp;
arg.partid = partid;
+ arg.sync = sync;

guard(srcu)(&mpam_srcu);
list_for_each_entry_srcu(vmsc, &comp->vmsc, comp_list,
diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index 16ce968344d0..90c8f8d16c79 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -464,7 +464,7 @@ void mpam_disable(struct work_struct *work);
void mpam_reset_class_locked(struct mpam_class *class);

int mpam_apply_config(struct mpam_component *comp, u16 partid,
- struct mpam_config *cfg);
+ struct mpam_config *cfg, bool sync);

int mpam_msmon_read(struct mpam_component *comp, struct mon_cfg *ctx,
enum mpam_device_features, u64 *val);
diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index 2762462d80e5..5a97a7f18670 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -1329,15 +1329,15 @@ int resctrl_arch_update_one(struct rdt_resource *r, struct rdt_ctrl_domain *d,
*/
if (mpam_resctrl_hide_cdp(r->rid)) {
partid = resctrl_get_config_index(closid, CDP_CODE);
- err = mpam_apply_config(dom->ctrl_comp, partid, &cfg);
+ err = mpam_apply_config(dom->ctrl_comp, partid, &cfg, false);
if (err)
return err;

partid = resctrl_get_config_index(closid, CDP_DATA);
- return mpam_apply_config(dom->ctrl_comp, partid, &cfg);
+ return mpam_apply_config(dom->ctrl_comp, partid, &cfg, false);
}

- return mpam_apply_config(dom->ctrl_comp, partid, &cfg);
+ return mpam_apply_config(dom->ctrl_comp, partid, &cfg, false);
}

int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid)
@@ -1718,6 +1718,23 @@ static void update_rmid_entries_for_reqpartid(u32 reqpartid)
rmid_entry_reassign_closid(closid, req_pmg2rmid(reqpartid, pmg));
}

+static int mpam_sync_config(u32 reqpartid)
+{
+ struct mpam_component *comp;
+ struct mpam_class *class;
+ int err;
+
+ list_for_each_entry(class, &mpam_classes, classes_list) {
+ list_for_each_entry(comp, &class->components, class_list) {
+ err = mpam_apply_config(comp, reqpartid, NULL, true);
+ if (err)
+ return err;
+ }
+ }
+
+ return 0;
+}
+
int resctrl_arch_rmid_expand(u32 closid)
{
int i;
@@ -1729,14 +1746,20 @@ int resctrl_arch_rmid_expand(u32 closid)
if (reqpartid_map[i] >= resctrl_arch_get_num_closid(NULL)) {
if (cdp_enabled) {
reqpartid_map[i] = resctrl_get_config_index(closid, CDP_DATA);
+ mpam_sync_config(i);
+
/*
* Reqpartids are always allocated in
* pairs, never out-of-bounds access.
*/
reqpartid_map[i + 1] = resctrl_get_config_index(closid, CDP_CODE);
+ mpam_sync_config(i + 1);
+
} else {
reqpartid_map[i] = resctrl_get_config_index(closid, CDP_NONE);
+ mpam_sync_config(i);
}
+
update_rmid_entries_for_reqpartid(i);
return i;
}
--
2.25.1