[PATCH v7 8/8] x86/resctrl: Display hardware ids of resource groups

[Babu Moger]

In x86, hardware uses CLOSID and an RMID to identify a control group and
a monitoring group respectively. When a user creates a control or monitor
group these details are not visible to the user. These details can help
debugging.

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

Other architectures do not use "CLOSID" and "RMID". Use the names
ctrl_hw_id and mon_hw_id to refer "CLOSID" and "RMID" respectively in an
effort to keep the naming generic.

For example:
 $cat /sys/fs/resctrl/ctrl_grp1/ctrl_hw_id
 1
 $cat /sys/fs/resctrl/mon_groups/mon_grp1/mon_hw_id
 3

Reviewed-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
Tested-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
 Documentation/arch/x86/resctrl.rst     |    8 ++++++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c |   46 ++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 5a2346d2c561..41ad9b1f0c6a 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -351,6 +351,10 @@ When control is enabled all CTRL_MON groups will also contain:
 	file. On successful pseudo-locked region creation the mode will
 	automatically change to "pseudo-locked".
 
+"ctrl_hw_id":
+	Available only with debug option. The identifier used by hardware
+	for the control group. On x86 this is the CLOSID.
+
 When monitoring is enabled all MON groups will also contain:
 
 "mon_data":
@@ -364,6 +368,10 @@ 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/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 6b7e914657fa..94471ad9d905 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -776,6 +776,38 @@ static int rdtgroup_tasks_show(struct kernfs_open_file *of,
 	return ret;
 }
 
+static int rdtgroup_closid_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->closid);
+	else
+		ret = -ENOENT;
+	rdtgroup_kn_unlock(of->kn);
+
+	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
 
 /*
@@ -1837,6 +1869,13 @@ 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_BASE | RFTYPE_DEBUG,
+	},
 	{
 		.name		= "schemata",
 		.mode		= 0644,
@@ -1860,6 +1899,13 @@ static struct rftype res_common_files[] = {
 		.seq_show	= rdtgroup_size_show,
 		.fflags		= RFTYPE_CTRL_BASE,
 	},
+	{
+		.name		= "ctrl_hw_id",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdtgroup_closid_show,
+		.fflags		= RFTYPE_CTRL_BASE | RFTYPE_DEBUG,
+	},
 
 };