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[mpam,mpam/snapshot/v6.14-rc1,v2,2/5] arm_mpam: Add limitation for the Narrow-PARTID feature

Message ID 20250222112448.2438586-3-zengheng4@huawei.com (mailing list archive)
State New
Headers show
Series arm_mpam: Introduce the Narrow-PARTID feature for MPAM driver | expand

Commit Message

Zeng Heng Feb. 22, 2025, 11:24 a.m. UTC
Because it needs to support mixed systems that include MSCs with and
without Narrow-PARTID support, there are the following incompatible
control issues.

If an MSC does not support Narrow-PARTID and its control method is not of
the "partition bitmap" type, then delivering the resctrl control group
configuration across multiple PARTIDs will change the user's expected
behavior.

Currently, there is no way to solve this problem by programming different
control values simply, so here decide to restrict the usage scenarios of
this feature. When we find that the MATA MSC does not support the
Narrow-PARTID feature, the driver will disable the feature, which means
get_num_reqpartid() directly returns the number of intPARTIDs.

Signed-off-by: Zeng Heng <zengheng4@huawei.com>
---
 drivers/platform/arm64/mpam/mpam_resctrl.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
diff mbox series

Patch

diff --git a/drivers/platform/arm64/mpam/mpam_resctrl.c b/drivers/platform/arm64/mpam/mpam_resctrl.c
index eedd308d9c88..f3f8fb0ff421 100644
--- a/drivers/platform/arm64/mpam/mpam_resctrl.c
+++ b/drivers/platform/arm64/mpam/mpam_resctrl.c
@@ -168,6 +168,21 @@  u32 resctrl_arch_get_num_closid(struct rdt_resource *ignored)
 
 static u32 get_num_reqpartid(void)
 {
+	struct mpam_resctrl_res *res;
+	struct rdt_resource *r_mba;
+	struct mpam_props *cprops;
+
+	r_mba = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
+	res = container_of(r_mba, struct mpam_resctrl_res, resctrl_res);
+	cprops = &res->class->props;
+
+	/*
+	 * If the MBA does not support Narrow-PARTID,
+	 * then the feature should be disabled at the system level.
+	 */
+	if (!mpam_has_feature(mpam_feat_partid_nrw, cprops))
+		return resctrl_arch_get_num_closid(NULL);
+
 	return mpam_partid_max + 1;
 }