[PATCH v9 9/9] x86/resctrl: Display RMID of resource group

[Babu Moger <babu.moger@xxxxxxx>]

In x86, hardware uses RMID to identify a a monitoring group. When a
user creates a monitor group these details are not visible. These details
can help resctrl debugging.

Add RMID(mon_hw_id) to the monitor groups display in resctrl interface.
Users can see these details when resctrl is mounted with "-o debug" option.

Other architectures do not use "RMID". Use the name mon_hw_id to refer
to "RMID" in an effort to keep the naming generic.

Add the flag RFTYPE_MON_BASE, which contains the files required only
for the MON group.

For example:
 $cat /sys/fs/resctrl/mon_groups/mon_grp1/mon_hw_id
 3

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
 Documentation/arch/x86/resctrl.rst     |  4 +++
 arch/x86/kernel/cpu/resctrl/internal.h |  6 ++++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 38 +++++++++++++++++++++++---
 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 54691c8b832d..98b0eb509ed4 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -369,6 +369,10 @@ When monitoring is enabled all MON groups will also contain:
 	the sum for all tasks in the CTRL_MON group and all tasks in
 	MON groups. Please see example section for more details on usage.
 
+"mon_hw_id":
+	Available only with debug option. The identifier used by hardware
+	for the monitor group. On x86 this is the RMID.
+
 Resource allocation rules
 -------------------------
 
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index ccdbed615d41..b4910892b0a6 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -296,6 +296,11 @@ struct rdtgroup {
  *	--> RFTYPE_BASE (Files common for both MON and CTRL groups)
  *	    Files: cpus, cpus_list, tasks
  *
+ *		--> RFTYPE_MON (Files only for MON group)
+ *
+ *			--> RFTYPE_DEBUG (Files to help resctrl debugging)
+ *			    File: mon_hw_id
+ *
  *		--> RFTYPE_CTRL (Files only for CTRL group)
  *		    Files: mode, schemata, size
  *
@@ -315,6 +320,7 @@ struct rdtgroup {
 #define RFTYPE_MON_INFO			(RFTYPE_INFO | RFTYPE_MON)
 #define RFTYPE_TOP_INFO			(RFTYPE_INFO | RFTYPE_TOP)
 #define RFTYPE_CTRL_BASE		(RFTYPE_BASE | RFTYPE_CTRL)
+#define RFTYPE_MON_BASE			(RFTYPE_BASE | RFTYPE_MON)
 
 /* List of all resource groups */
 extern struct list_head rdt_all_groups;
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 8be0fb323ad3..fc830ffce82a 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -795,6 +795,22 @@ static int rdtgroup_closid_show(struct kernfs_open_file *of,
 	return ret;
 }
 
+static int rdtgroup_rmid_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->mon.rmid);
+	else
+		ret = -ENOENT;
+	rdtgroup_kn_unlock(of->kn);
+
+	return ret;
+}
+
 #ifdef CONFIG_PROC_CPU_RESCTRL
 
 /*
@@ -1856,6 +1872,13 @@ static struct rftype res_common_files[] = {
 		.seq_show	= rdtgroup_tasks_show,
 		.fflags		= RFTYPE_BASE,
 	},
+	{
+		.name		= "mon_hw_id",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdtgroup_rmid_show,
+		.fflags		= RFTYPE_MON_BASE | RFTYPE_DEBUG,
+	},
 	{
 		.name		= "schemata",
 		.mode		= 0644,
@@ -2535,6 +2558,7 @@ static void schemata_list_destroy(void)
 static int rdt_get_tree(struct fs_context *fc)
 {
 	struct rdt_fs_context *ctx = rdt_fc2context(fc);
+	unsigned long flags = RFTYPE_CTRL_BASE;
 	struct rdt_domain *dom;
 	struct rdt_resource *r;
 	int ret;
@@ -2565,7 +2589,10 @@ static int rdt_get_tree(struct fs_context *fc)
 
 	closid_init();
 
-	ret = rdtgroup_add_files(rdtgroup_default.kn, RFTYPE_CTRL_BASE);
+	if (rdt_mon_capable)
+		flags |= RFTYPE_MON;
+
+	ret = rdtgroup_add_files(rdtgroup_default.kn, flags);
 	if (ret)
 		goto out_schemata_free;
 
@@ -3255,8 +3282,8 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
 			     enum rdt_group_type rtype, struct rdtgroup **r)
 {
 	struct rdtgroup *prdtgrp, *rdtgrp;
+	unsigned long files = 0;
 	struct kernfs_node *kn;
-	uint files = 0;
 	int ret;
 
 	prdtgrp = rdtgroup_kn_lock_live(parent_kn);
@@ -3308,10 +3335,13 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
 		goto out_destroy;
 	}
 
-	if (rtype == RDTCTRL_GROUP)
+	if (rtype == RDTCTRL_GROUP) {
 		files = RFTYPE_BASE | RFTYPE_CTRL;
-	else
+		if (rdt_mon_capable)
+			files |= RFTYPE_MON;
+	} else {
 		files = RFTYPE_BASE | RFTYPE_MON;
+	}
 
 	ret = rdtgroup_add_files(kn, files);
 	if (ret) {
-- 
2.34.1