The narrow-partid feature in MPAM allows for a more efficient use of
PARTIDs by enabling a many-to-one mapping of reqpartids (requested PARTIDs)
to intpartids (internal PARTIDs). This mapping reduces the number of unique
PARTIDs needed, thus allowing more tasks or processes to be monitored and
managed with the available resources.

Intpartid(Internal PARTID) is an internal identifier used by the hardware
to represent a specific resource partition. It is a low-level identifier
that the hardware uses to track and manage resource allocation and
monitoring.

Reqpartid(Request PARTID) is an identifier provided by the software when
requesting resources from the memory system. It indicates the desired
partition for resource monitoring. By using reqpartids, software can
monitor specific resources or allow the system to subdivide smaller
granularity partitions within existing partitions to serve as monitoring
partitions.

Regarding intPARTID, MPAM uses it as the unit for control group
configuration delivery. MPAM will synchronize the delivered configuration
to all reqPARTIDs mapped to the same intPARTIDs. The number of intPARTIDs
is indicated by MPAMF_PARTID_NRW_IDR.INTPARTID_MAX if implemented, or
directly use the number of PARTID as intpartid_max.

reqPARTIDs can be used to expand the number of monitors, for each control
group is no longer simply restricted by the range of PMG. By mapping
between intPARTID and reqPARTID, the number of monitors would be greatly
expanded and more fine-grained monitoring under a control group will be
achieved.

After initialization, MPAM driver would select the minimum intpartid_max
among all classes of MSCs as the number of CLOSIDs, and use partid_max as
the number of reqPARTIDs.

Signed-off-by: Zeng Heng <zengheng4@huawei.com>
---
 drivers/platform/arm64/mpam/mpam_devices.c  | 12 +++++++++++-
 drivers/platform/arm64/mpam/mpam_internal.h |  2 ++
 drivers/platform/arm64/mpam/mpam_resctrl.c  |  9 +++++++--
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/arm64/mpam/mpam_devices.c b/drivers/platform/arm64/mpam/mpam_devices.c
index e7ab1bfbf831..1bcdeb847a22 100644
--- a/drivers/platform/arm64/mpam/mpam_devices.c
+++ b/drivers/platform/arm64/mpam/mpam_devices.c
@@ -67,6 +67,7 @@ static DEFINE_MUTEX(mpam_cpuhp_state_lock);
  * Generating traffic outside this range will result in screaming interrupts.
  */
 u16 mpam_partid_max;
+u16 mpam_intpartid_max;
 u8 mpam_pmg_max;
 static bool partid_max_init, partid_max_published;
 static DEFINE_SPINLOCK(partid_max_lock);
@@ -234,10 +235,16 @@ int mpam_register_requestor(u16 partid_max, u8 pmg_max)
 	spin_lock(&partid_max_lock);
 	if (!partid_max_init) {
 		mpam_partid_max = partid_max;
+		/*
+		 * Update mpam_intpartid_max here, in case the
+		 * system doesn't have narrow-partid feature.
+		 */
+		mpam_intpartid_max = partid_max;
 		mpam_pmg_max = pmg_max;
 		partid_max_init = true;
 	} else if (!partid_max_published) {
 		mpam_partid_max = min(mpam_partid_max, partid_max);
+		mpam_intpartid_max = min(mpam_intpartid_max, partid_max);
 		mpam_pmg_max = min(mpam_pmg_max, pmg_max);
 	} else {
 		/* New requestors can't lower the values */
@@ -988,7 +995,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
 		u16 partid_max = FIELD_GET(MPAMF_PARTID_NRW_IDR_INTPARTID_MAX, nrwidr);
 
 		mpam_set_feature(mpam_feat_partid_nrw, props);
-		msc->partid_max = min(msc->partid_max, partid_max);
+		msc->intpartid_max = min(msc->partid_max, partid_max);
+	} else {
+		msc->intpartid_max = msc->partid_max;
 	}
 
 	mpam_mon_sel_outer_unlock(msc);
@@ -1050,6 +1059,7 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc)
 
 	spin_lock(&partid_max_lock);
 	mpam_partid_max = min(mpam_partid_max, msc->partid_max);
+	mpam_intpartid_max = min(mpam_intpartid_max, msc->intpartid_max);
 	mpam_pmg_max = min(mpam_pmg_max, msc->pmg_max);
 	spin_unlock(&partid_max_lock);
 
diff --git a/drivers/platform/arm64/mpam/mpam_internal.h b/drivers/platform/arm64/mpam/mpam_internal.h
index a7113ba12a22..db1d990bc42b 100644
--- a/drivers/platform/arm64/mpam/mpam_internal.h
+++ b/drivers/platform/arm64/mpam/mpam_internal.h
@@ -80,6 +80,7 @@ struct mpam_msc
 	bool			error_irq_requested;
 	bool			error_irq_hw_enabled;
 	u16			partid_max;
+	u16			intpartid_max;
 	u8			pmg_max;
 	unsigned long		ris_idxs[128 / BITS_PER_LONG];
 	u32			ris_max;
@@ -455,6 +456,7 @@ static inline void mpam_assert_srcu_read_lock_held(void)
 
 /* System wide partid/pmg values */
 extern u16 mpam_partid_max;
+extern u16 mpam_intpartid_max;
 extern u8 mpam_pmg_max;
 
 /* Scheduled work callback to enable mpam once all MSC have been probed */
diff --git a/drivers/platform/arm64/mpam/mpam_resctrl.c b/drivers/platform/arm64/mpam/mpam_resctrl.c
index cc50337e10b0..a74133d7b402 100644
--- a/drivers/platform/arm64/mpam/mpam_resctrl.c
+++ b/drivers/platform/arm64/mpam/mpam_resctrl.c
@@ -162,6 +162,11 @@ static bool mpam_resctrl_hide_cdp(enum resctrl_res_level rid)
  * only the system wide safe value is safe to use.
  */
 u32 resctrl_arch_get_num_closid(struct rdt_resource *ignored)
+{
+	return mpam_intpartid_max + 1;
+}
+
+static u32 get_num_reqpartid(void)
 {
 	return mpam_partid_max + 1;
 }
@@ -169,9 +174,9 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *ignored)
 u32 resctrl_arch_system_num_rmid_idx(void)
 {
 	u8 closid_shift = fls(mpam_pmg_max);
-	u32 num_partid = resctrl_arch_get_num_closid(NULL);
+	u32 num_reqpartid = get_num_reqpartid();
 
-	return num_partid << closid_shift;
+	return num_reqpartid << closid_shift;
 }
 
 u32 resctrl_arch_rmid_idx_encode(u32 closid, u32 rmid)
-- 
2.25.1