linux-kernel - [RFC PATCH 15/19] fs/resctrl: Introduce PLZA attribute in rdtgroup interface

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Message-ID: <e6fbb7786b0b8cc0d2ef82f7c9a37facc42d245a.1769029977.git.babu.moger@amd.com>
Date: Wed, 21 Jan 2026 15:12:53 -0600
From: Babu Moger <babu.moger@....com>
To: <corbet@....net>, <tony.luck@...el.com>, <reinette.chatre@...el.com>,
	<Dave.Martin@....com>, <james.morse@....com>, <babu.moger@....com>,
	<tglx@...nel.org>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>
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Subject: [RFC PATCH 15/19] fs/resctrl: Introduce PLZA attribute in rdtgroup interface

Add plza attribute to display Privilege Level Zero Association for the
resctrl group.

Signed-off-by: Babu Moger <babu.moger@....com>
---
 fs/resctrl/internal.h |  2 ++
 fs/resctrl/rdtgroup.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index 1a9b29119f88..c107c1328be6 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -215,6 +215,7 @@ struct mongroup {
  *				monitor only or ctrl_mon group
  * @mon:			mongroup related data
  * @mode:			mode of resource group
+ * @plza:			Is Privilege Level Zero Association enabled?
  * @mba_mbps_event:		input monitoring event id when mba_sc is enabled
  * @plr:			pseudo-locked region
  */
@@ -228,6 +229,7 @@ struct rdtgroup {
 	enum rdt_group_type		type;
 	struct mongroup			mon;
 	enum rdtgrp_mode		mode;
+	bool				plza;
 	enum resctrl_event_id		mba_mbps_event;
 	struct pseudo_lock_region	*plr;
 };
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 616be6633a6d..d467b52a0c74 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -880,6 +880,22 @@ static int rdtgroup_rmid_show(struct kernfs_open_file *of,
 	return ret;
 }
 
+static int rdtgroup_plza_show(struct kernfs_open_file *of,
+			      struct seq_file *s, void *v)
+{
+	struct rdtgroup *rdtgrp;
+	int ret = 0;
+
+	rdtgrp = rdtgroup_kn_lock_live(of->kn);
+	if (rdtgrp)
+		seq_printf(s, "%u\n", rdtgrp->plza);
+	else
+		ret = -ENOENT;
+	rdtgroup_kn_unlock(of->kn);
+
+	return ret;
+}
+
 #ifdef CONFIG_PROC_CPU_RESCTRL
 /*
  * A task can only be part of one resctrl control group and of one monitor
@@ -2153,6 +2169,12 @@ static struct rftype res_common_files[] = {
 		.seq_show	= rdtgroup_closid_show,
 		.fflags		= RFTYPE_CTRL_BASE | RFTYPE_DEBUG,
 	},
+	{
+		.name		= "plza",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdtgroup_plza_show,
+	},
 };
 
 static int rdtgroup_add_files(struct kernfs_node *kn, unsigned long fflags)
@@ -2251,6 +2273,14 @@ static void io_alloc_init(void)
 	}
 }
 
+static void resctrl_plza_init(void)
+{
+	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
+
+	if (r->plza_capable)
+		resctrl_file_fflags_init("plza", RFTYPE_CTRL_BASE);
+}
+
 void resctrl_file_fflags_init(const char *config, unsigned long fflags)
 {
 	struct rftype *rft;
@@ -4609,6 +4639,8 @@ int resctrl_init(void)
 
 	io_alloc_init();
 
+	resctrl_plza_init();
+
 	ret = resctrl_l3_mon_resource_init();
 	if (ret)
 		return ret;
-- 
2.34.1