Message-ID: <8213746e89e4813e397043325520353ada56651d.1752013061.git.babu.moger@amd.com>
Date: Tue, 8 Jul 2025 17:17:36 -0500
From: Babu Moger <babu.moger@....com>
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Subject: [PATCH v15 27/34] fs/resctrl: Provide interface to update the event configurations

When "mbm_event" counter assignment mode is supported, users can modify
the event configuration by writing to the 'event_filter' resctrl file.
The event configurations for mbm_event mode are located in
/sys/fs/resctrl/info/L3_MON/event_configs/.

Update the assignments of all CTRL_MON and MON resource groups when the
event configuration is modified.

Example:
$ mount -t resctrl resctrl /sys/fs/resctrl

$ cd /sys/fs/resctrl/

$ cat info/L3_MON/event_configs/mbm_local_bytes/event_filter
  local_reads,local_non_temporal_writes,local_reads_slow_memory

$ echo "local_reads,local_non_temporal_writes" >
  info/L3_MON/event_configs/mbm_total_bytes/event_filter

$ cat info/L3_MON/event_configs/mbm_total_bytes/event_filter
  local_reads,local_non_temporal_writes

Signed-off-by: Babu Moger <babu.moger@....com>
---
v15: Updated changelog.
     Updated spacing in resctrl.rst.
     Corrected the name counter_configs -> event_configs.
     Changed the name rdtgroup_assign_cntr() > rdtgroup_update_cntr_event().
     Removed the code to check d->cntr_cfg[cntr_id].evt_cfg.
     Fixed the partial initialization of val in resctrl_process_configs().
     Passed mon_evt where applicable. The struct rdt_resource can be obtained from mon_evt::rid.

v14: Passed struct mon_evt where applicable instead of just the event type.
     Fixed few text corrections about memory trasaction type.
     Renamed few functions resctrl_group_assign() -> rdtgroup_assign_cntr()
     resctrl_update_assign() -> resctrl_assign_cntr_allrdtgrp()
     Removed few extra bases.

v13: Updated changelog for imperative mode.
     Added function description in the prototype.
     Updated the user doc resctrl.rst to address few feedback.
     Resolved conflicts caused by the recent FS/ARCH code restructure.
     The rdtgroup.c/monitor.c file has now been split between the FS and ARCH directories.

v12: New patch to modify event configurations.
---
 Documentation/filesystems/resctrl.rst | 12 +++++
 fs/resctrl/internal.h                 |  1 +
 fs/resctrl/monitor.c                  | 44 ++++++++++++++++
 fs/resctrl/rdtgroup.c                 | 74 ++++++++++++++++++++++++++-
 4 files changed, 130 insertions(+), 1 deletion(-)

diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index 57fd12f0aeca..06c8c08d0341 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -342,6 +342,18 @@ with the following files:
 	  # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_local_bytes/event_filter
 	  local_reads,local_non_temporal_writes,local_reads_slow_memory
 
+	Modify the event configuration by writing to the "event_filter" file within
+	the "event_configs" directory. The read/write "event_filter" file contains the
+	configuration of the event that reflects which memory transactions are counted by it.
+
+	For example::
+
+	  # echo "local_reads, local_non_temporal_writes" >
+	    /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter
+
+	  # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter
+	   local_reads,local_non_temporal_writes
+
 "max_threshold_occupancy":
 		Read/write file provides the largest value (in
 		bytes) at which a previously used LLC_occupancy
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index b107874407b2..b42890fd937a 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -409,6 +409,7 @@ void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdt
 				  struct mon_evt *mevt);
 int mbm_cntr_get(struct rdt_resource *r, struct rdt_mon_domain *d,
 		 struct rdtgroup *rdtgrp, enum resctrl_event_id evtid);
+void resctrl_update_cntr_allrdtgrp(struct mon_evt *mevt);
 
 #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
 int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 787dce934903..0722e72f6cb1 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -1173,3 +1173,47 @@ void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdt
 		rdtgroup_free_config_cntr(r, d, rdtgrp, mevt->evtid);
 	}
 }
+
+/*
+ * rdtgroup_update_cntr_event - Update the counter assignments for the event
+ *				in a group.
+ * @r:		Resource to which update needs to be done.
+ * @rdtgrp:	Resctrl group.
+ * @mevt:	MBM monitor event.
+ */
+static void rdtgroup_update_cntr_event(struct rdt_resource *r, struct rdtgroup *rdtgrp,
+				       enum resctrl_event_id evtid)
+{
+	struct rdt_mon_domain *d;
+	int cntr_id;
+
+	list_for_each_entry(d, &r->mon_domains, hdr.list) {
+		cntr_id = mbm_cntr_get(r, d, rdtgrp, evtid);
+		if (cntr_id >= 0)
+			resctrl_arch_config_cntr(r, d, evtid, rdtgrp->mon.rmid,
+						 rdtgrp->closid, cntr_id, true);
+	}
+}
+
+/*
+ * resctrl_update_cntr_allrdtgrp - Update the counter assignments for the event
+ *				   for all the groups.
+ * @r:		Resource to which update needs to be done.
+ * @mevt	MBM Monitor event.
+ */
+void resctrl_update_cntr_allrdtgrp(struct mon_evt *mevt)
+{
+	struct rdt_resource *r = resctrl_arch_get_resource(mevt->rid);
+	struct rdtgroup *prgrp, *crgrp;
+
+	/*
+	 * Find all the groups where the event is assigned and update
+	 * the assignment
+	 */
+	list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
+		rdtgroup_update_cntr_event(r, prgrp, mevt->evtid);
+
+		list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list)
+			rdtgroup_update_cntr_event(r, crgrp, mevt->evtid);
+	}
+}
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index bb28ef7e4600..4889e7556cc7 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1916,6 +1916,77 @@ static int event_filter_show(struct kernfs_open_file *of, struct seq_file *seq,
 	return 0;
 }
 
+static int resctrl_process_configs(char *tok, u32 *val)
+{
+	u32 temp_val = 0;
+	char *evt_str;
+	bool found;
+	int i;
+
+next_config:
+	if (!tok || tok[0] == '\0') {
+		*val = temp_val;
+		return 0;
+	}
+
+	/* Start processing the strings for each memory transaction type */
+	evt_str = strim(strsep(&tok, ","));
+	found = false;
+	for (i = 0; i < NUM_MBM_TRANSACTIONS; i++) {
+		if (!strcmp(mbm_transactions[i].name, evt_str)) {
+			temp_val |= mbm_transactions[i].val;
+			found = true;
+			break;
+		}
+	}
+
+	if (!found) {
+		rdt_last_cmd_printf("Invalid memory transaction type %s\n", evt_str);
+		return -EINVAL;
+	}
+
+	goto next_config;
+}
+
+static ssize_t event_filter_write(struct kernfs_open_file *of, char *buf,
+				  size_t nbytes, loff_t off)
+{
+	struct mon_evt *mevt = rdt_kn_parent_priv(of->kn);
+	struct rdt_resource *r;
+	u32 evt_cfg = 0;
+	int ret = 0;
+
+	/* Valid input requires a trailing newline */
+	if (nbytes == 0 || buf[nbytes - 1] != '\n')
+		return -EINVAL;
+
+	buf[nbytes - 1] = '\0';
+
+	cpus_read_lock();
+	mutex_lock(&rdtgroup_mutex);
+
+	rdt_last_cmd_clear();
+
+	r = resctrl_arch_get_resource(mevt->rid);
+	if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
+		rdt_last_cmd_puts("mbm_event counter assignment mode is not enabled\n");
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	ret = resctrl_process_configs(buf, &evt_cfg);
+	if (!ret && mevt->evt_cfg != evt_cfg) {
+		mevt->evt_cfg = evt_cfg;
+		resctrl_update_cntr_allrdtgrp(mevt);
+	}
+
+out_unlock:
+	mutex_unlock(&rdtgroup_mutex);
+	cpus_read_unlock();
+
+	return ret ?: nbytes;
+}
+
 /* rdtgroup information files for one cache resource. */
 static struct rftype res_common_files[] = {
 	{
@@ -2042,9 +2113,10 @@ static struct rftype res_common_files[] = {
 	},
 	{
 		.name		= "event_filter",
-		.mode		= 0444,
+		.mode		= 0644,
 		.kf_ops		= &rdtgroup_kf_single_ops,
 		.seq_show	= event_filter_show,
+		.write		= event_filter_write,
 	},
 	{
 		.name		= "mbm_assign_mode",
-- 
2.34.1

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