[PATCH v14 28/32] fs/resctrl: Introduce mbm_L3_assignments to list assignments in a group

[Babu Moger]

Introduce the interface to display the assignment states for resctrl group
when "mbm_event" mdoe is enabled.

The list is displayed in the following format:
<Event>:<Domain id>=<Assignment state>

Event: A valid MBM event listed in
       /sys/fs/resctrl/info/L3_MON/event_configs directory.

Domain ID: A valid domain ID.

The assignment state can be one of the following:

_ : No counter assigned.

e : Counter assigned exclusively.

Example:
To list the assignment states for the default group
$ cd /sys/fs/resctrl
$ cat /sys/fs/resctrl/mbm_L3_assignments
mbm_total_bytes:0=e;1=e
mbm_local_bytes:0=e;1=e

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
v14: Added missed rdtgroup_kn_lock_live on failure case.
     Updated the user doc resctrl.rst to clarify counter assignments.
     Updated the changelog.

v13: Changelog update.
     Few changes in mbm_L3_assignments_show() after moving the event config to evt_list.
     Resolved conflicts caused by the recent FS/ARCH code restructure.
     The rdtgroup.c/monitor.c files have been split between the FS and ARCH directories.

v12: New patch:
     Assignment interface moved inside the group based the discussion
     https://lore.kernel.org/lkml/CALPaoCiii0vXOF06mfV=kVLBzhfNo0SFqt4kQGwGSGVUqvr2Dg@xxxxxxxxxxxxxx/#t
---
 Documentation/filesystems/resctrl.rst | 28 ++++++++++++++
 fs/resctrl/monitor.c                  |  1 +
 fs/resctrl/rdtgroup.c                 | 54 +++++++++++++++++++++++++++
 3 files changed, 83 insertions(+)

diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index f94c7c387416..a232a0b1356c 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -516,6 +516,34 @@ When the "mba_MBps" mount option is used all CTRL_MON groups will also contain:
 	/sys/fs/resctrl/info/L3_MON/mon_features changes the input
 	event.
 
+"mbm_L3_assignments":
+	Exists when "mbm_event" mode is supported and lists the counter
+	assignment states for the group.
+
+	The assignment list is displayed in the following format:
+
+	<Event>:<Domain ID>=<Assignment state>
+
+	Event: A valid MBM event in the
+	       /sys/fs/resctrl/info/L3_MON/event_configs directory.
+
+	Domain ID: A valid domain ID.
+
+	Assignment states:
+
+	_ : No counter assigned.
+
+	e : Counter assigned exclusively.
+
+	Example:
+	To display the counter assignment states for the default group.
+	::
+
+	 # cd /sys/fs/resctrl
+	 # cat /sys/fs/resctrl/mbm_L3_assignments
+	   mbm_total_bytes:0=e;1=e
+	   mbm_local_bytes:0=e;1=e
+
 Resource allocation rules
 -------------------------
 
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 1ec2efd50273..618c94cd1ad8 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -959,6 +959,7 @@ int resctrl_mon_resource_init(void)
 		resctrl_file_fflags_init("event_filter", RFTYPE_ASSIGN_CONFIG);
 		resctrl_file_fflags_init("mbm_assign_on_mkdir", RFTYPE_MON_INFO |
 					 RFTYPE_RES_CACHE);
+		resctrl_file_fflags_init("mbm_L3_assignments", RFTYPE_MON_BASE);
 	}
 
 	return 0;
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 128a9db339f3..18ec65801dbb 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -2081,6 +2081,54 @@ static ssize_t resctrl_mbm_assign_on_mkdir_write(struct kernfs_open_file *of,
 	return ret ?: nbytes;
 }
 
+static int mbm_L3_assignments_show(struct kernfs_open_file *of, struct seq_file *s, void *v)
+{
+	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
+	struct rdt_mon_domain *d;
+	struct rdtgroup *rdtgrp;
+	struct mon_evt *mevt;
+	int ret = 0;
+	bool sep;
+
+	rdtgrp = rdtgroup_kn_lock_live(of->kn);
+	if (!rdtgrp) {
+		ret = -ENOENT;
+		goto out_assign;
+	}
+
+	rdt_last_cmd_clear();
+	if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
+		rdt_last_cmd_puts("mbm_event mode is not enabled\n");
+		ret = -ENOENT;
+		goto out_assign;
+	}
+
+	for (mevt = &mon_event_all[0]; mevt < &mon_event_all[QOS_NUM_EVENTS]; mevt++) {
+		if (!mevt->enabled || !resctrl_is_mbm_event(mevt->evtid))
+			continue;
+
+		sep = false;
+		seq_printf(s, "%s:", mevt->name);
+		list_for_each_entry(d, &r->mon_domains, hdr.list) {
+			if (sep)
+				seq_putc(s, ';');
+
+			if (mbm_cntr_get(r, d, rdtgrp, mevt->evtid) >= 0)
+				seq_printf(s, "%d=e", d->hdr.id);
+			else
+				seq_printf(s, "%d=_", d->hdr.id);
+
+			sep = true;
+		}
+		seq_putc(s, '\n');
+	}
+
+out_assign:
+	rdtgroup_kn_unlock(of->kn);
+
+	return ret;
+}
+
 /* rdtgroup information files for one cache resource. */
 static struct rftype res_common_files[] = {
 	{
@@ -2219,6 +2267,12 @@ static struct rftype res_common_files[] = {
 		.seq_show	= event_filter_show,
 		.write		= event_filter_write,
 	},
+	{
+		.name		= "mbm_L3_assignments",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= mbm_L3_assignments_show,
+	},
 	{
 		.name		= "mbm_assign_mode",
 		.mode		= 0444,
-- 
2.34.1