[PATCH v12 20/26] x86/resctrl: Provide interface to update the event configurations

[Babu Moger]

Users can modify the event configuration by writing to the event_filter
interface file. The event configurations for mbm_cntr_assign mode are
located in /sys/fs/resctrl/info/event_configs/.

Update the assignments of all groups when the event configuration is
modified.

Example:
$ cd /sys/fs/resctrl/
$ echo "local_reads, local_non_temporal_writes" >
  info/L3_MON/counter_configs/mbm_total_bytes/event_filter

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

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
v12: New patch to modify event configurations.
---
 Documentation/arch/x86/resctrl.rst     |  10 +++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 115 ++++++++++++++++++++++++-
 2 files changed, 124 insertions(+), 1 deletion(-)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 99f9f4b9b501..4e6feba6fb08 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -335,6 +335,16 @@ with the following files:
 	    # cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter
 	    local_reads, local_non_temporal_writes, local_reads_slow_memory
 
+	The event configuration can be modified by writing to the event_filter file within
+	the configuration directory.
+	::
+
+	    # echo "local_reads, local_non_temporal_writes" >
+	      /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_total_bytes/event_filter
+
+	    # cat /sys/fs/resctrl/info/L3_MON/counter_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/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index b2122a1dd36c..7792455f0b26 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1926,6 +1926,118 @@ static int event_filter_show(struct kernfs_open_file *of, struct seq_file *seq,
 	return 0;
 }
 
+static int resctrl_group_assign(struct rdt_resource *r, struct rdtgroup *rdtgrp,
+				enum resctrl_event_id evtid, u32 evt_cfg)
+{
+	struct rdt_mon_domain *d;
+	int cntr_id, ret;
+
+	list_for_each_entry(d, &r->mon_domains, hdr.list) {
+		cntr_id = mbm_cntr_get(r, d, rdtgrp, evtid);
+		if (cntr_id >= 0 && d->cntr_cfg[cntr_id].evt_cfg != evt_cfg) {
+			d->cntr_cfg[cntr_id].evt_cfg = evt_cfg;
+			ret = resctrl_arch_config_cntr(r, d, evtid, rdtgrp->mon.rmid,
+						       rdtgrp->closid, cntr_id, evt_cfg, true);
+			if (ret) {
+				rdt_last_cmd_printf("Assign failed event %d domain %d group %s\n",
+						    evtid, d->hdr.id, rdtgrp->kn->name);
+				return ret;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static int resctrl_update_assign(struct rdt_resource *r, enum resctrl_event_id evtid,
+				 u32 evt_cfg)
+{
+	struct rdtgroup *prgrp, *crgrp;
+	int ret;
+
+	/* Check if the cntr_id is associated to the event type updated */
+	list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
+		ret = resctrl_group_assign(r, prgrp, evtid, evt_cfg);
+		if (ret)
+			return ret;
+
+		list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list) {
+			ret = resctrl_group_assign(r, crgrp, evtid, evt_cfg);
+			if (ret)
+				return ret;
+		}
+	}
+
+	return 0;
+}
+
+static int resctrl_process_configs(char *tok, u32 *val)
+{
+	char *evt_str;
+	bool found;
+	int i;
+
+next_config:
+	if (!tok || tok[0] == '\0')
+		return 0;
+
+	/* Start processing the strings for each event type */
+	evt_str = strim(strsep(&tok, ","));
+	found = false;
+	for (i = 0; i < NUM_MBM_EVT_VALUES; i++) {
+		if (!strcmp(mbm_evt_values[i].evt_name, evt_str)) {
+			*val |=  mbm_evt_values[i].evt_val;
+			found = true;
+			break;
+		}
+	}
+
+	if (!found) {
+		rdt_last_cmd_printf("Invalid event 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 rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
+	struct mbm_assign_config *assign_config = of->kn->parent->priv;
+	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();
+
+	if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
+		rdt_last_cmd_puts("mbm_cntr_assign mode is not enabled\n");
+		ret = -EINVAL;
+		goto unlock_out;
+	}
+
+	ret = resctrl_process_configs(buf, &evt_cfg);
+	if (!ret && assign_config->val != evt_cfg) {
+		assign_config->val = evt_cfg;
+		ret = resctrl_update_assign(r, assign_config->evtid, evt_cfg);
+	}
+
+unlock_out:
+	mutex_unlock(&rdtgroup_mutex);
+	cpus_read_unlock();
+
+	return ret ?: nbytes;
+}
+
 /* rdtgroup information files for one cache resource. */
 static struct rftype res_common_files[] = {
 	{
@@ -2040,9 +2152,10 @@ 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