Enable the mbm_l3_assignments resctrl file to be used to modify counter
assignments of CTRL_MON and MON groups when the "mbm_event" counter
assignment mode is enabled.

The assignment modifications are done 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. When writing, '*' applies the changes
	   to all domains.

Assignment states:

    _ : Unassign the counter.

    e : Assign the counter exclusively.

Examples:

$ 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

To unassign the counter associated with the mbm_total_bytes event on
domain 0:

$ echo "mbm_total_bytes:0=_" > mbm_L3_assignments
$ cat /sys/fs/resctrl/mbm_L3_assignments
  mbm_total_bytes:0=_;1=e
  mbm_local_bytes:0=e;1=e

To unassign the counter associated with the mbm_total_bytes event on
all the domains:

$ echo "mbm_total_bytes:*=_" > mbm_L3_assignments
$ cat /sys/fs/resctrl/mbm_L3_assignments
  mbm_total_bytes:0=_;1=_
  mbm_local_bytes:0=e;1=e

Signed-off-by: Babu Moger <babu.moger@amd.com>
---
v15: Updated the changelog little bit.
     Fixed the spacing in event_filter display.
     Removed the enum ASSIGN_NONE etc. Not required anymore.
     Moved mbm_get_mon_event_by_name() to fs/resctrl/monitor.c
     Used the new macro for_each_mon_event().
     Renamed resctrl_get_assign_state() -> rdtgroup_modify_assign_state().
     Quite a few changes in resctrl_process_assign().
     Removed the found and domain variables.
     Called rdtgroup_modify_assign_state() directly where applicable.
     Removed couple of goto statements.

v14: Fixed the problem reported by Peter.
     Updated the changelog.
     Updated the user doc resctrl.rst.
     Added example section on how to use resctrl with mbm_assign_mode.

v13: Few changes in mbm_L3_assignments_write() after moving the event config to evt_list.
     Resolved conflicts caused by the recent FS/ARCH code restructure.

v12: New patch:
     Assignment interface moved inside the group based the discussion
     https://lore.kernel.org/lkml/CALPaoCiii0vXOF06mfV=kVLBzhfNo0SFqt4kQGwGSGVUqvr2Dg@mail.gmail.com/#t
---
 Documentation/filesystems/resctrl.rst | 146 +++++++++++++++++++++++++-
 fs/resctrl/internal.h                 |   2 +
 fs/resctrl/monitor.c                  |  18 ++++
 fs/resctrl/rdtgroup.c                 | 123 +++++++++++++++++++++-
 4 files changed, 287 insertions(+), 2 deletions(-)

diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index 4dd1d605d6ad..2b2acb55d8b1 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -527,7 +527,8 @@ When the "mba_MBps" mount option is used all CTRL_MON groups will also contain:
 	Event: A valid MBM event in the
 	       /sys/fs/resctrl/info/L3_MON/event_configs directory.
 
-	Domain ID: A valid domain ID.
+	Domain ID: A valid domain ID. When writing, '*' applies the changes
+		   to all the domains.
 
 	Assignment states:
 
@@ -544,6 +545,34 @@ When the "mba_MBps" mount option is used all CTRL_MON groups will also contain:
 	   mbm_total_bytes:0=e;1=e
 	   mbm_local_bytes:0=e;1=e
 
+	Assignments can be modified by writing to the interface.
+
+	Example:
+	To unassign the counter associated with the mbm_total_bytes event on domain 0:
+	::
+
+	 # echo "mbm_total_bytes:0=_" > /sys/fs/resctrl/mbm_L3_assignments
+	 # cat /sys/fs/resctrl/mbm_L3_assignments
+	   mbm_total_bytes:0=_;1=e
+	   mbm_local_bytes:0=e;1=e
+
+	To unassign the counter associated with the mbm_total_bytes event on all the domains:
+	::
+
+	 # echo "mbm_total_bytes:*=_" > /sys/fs/resctrl/mbm_L3_assignments
+	 # cat /sys/fs/resctrl/mbm_L3_assignments
+	   mbm_total_bytes:0=_;1=_
+	   mbm_local_bytes:0=e;1=e
+
+	To assign the counter associated with the mbm_total_bytes event on all domains in
+	exclusive mode:
+	::
+
+	 # echo "mbm_total_bytes:*=e" > /sys/fs/resctrl/mbm_L3_assignments
+	 # cat /sys/fs/resctrl/mbm_L3_assignments
+	   mbm_total_bytes:0=e;1=e
+	   mbm_local_bytes:0=e;1=e
+
 Resource allocation rules
 -------------------------
 
@@ -1579,6 +1608,121 @@ View the llc occupancy snapshot::
   # cat /sys/fs/resctrl/p1/mon_data/mon_L3_00/llc_occupancy
   11234000
 
+
+Examples on working with mbm_assign_mode
+========================================
+
+a. Check if MBM counter assignment mode is supported.
+::
+
+  #mount -t resctrl resctrl /sys/fs/resctrl/
+
+  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
+  [mbm_event]
+  default
+
+The "mbm_event" mode is detected and enabled.
+
+b. Check how many assignable counters are supported.
+::
+
+  # cat /sys/fs/resctrl/info/L3_MON/num_mbm_cntrs
+  0=32;1=32
+
+c. Check how many assignable counters are available for assignment in each domain.
+::
+
+  # cat /sys/fs/resctrl/info/L3_MON/available_mbm_cntrs
+  0=30;1=30
+
+d. To list the default group's assign states:
+::
+
+  # cat /sys/fs/resctrl/mbm_L3_assignments
+  mbm_total_bytes:0=e;1=e
+  mbm_local_bytes:0=e;1=e
+
+e.  To unassign the counter associated with the mbm_total_bytes event on domain 0:
+::
+
+  # echo "mbm_total_bytes:0=_" > /sys/fs/resctrl/mbm_L3_assignments
+  # cat /sys/fs/resctrl/mbm_L3_assignments
+  mbm_total_bytes:0=_;1=e
+  mbm_local_bytes:0=e;1=e
+
+f. To unassign the counter associated with the mbm_total_bytes event on all domains:
+::
+
+  # echo "mbm_total_bytes:*=_" > /sys/fs/resctrl/mbm_L3_assignments
+  # cat /sys/fs/resctrl/mbm_L3_assignment
+  mbm_total_bytes:0=_;1=_
+  mbm_local_bytes:0=e;1=e
+
+g. To assign a counter associated with the mbm_total_bytes event on all domains in
+exclusive mode:
+::
+
+  # echo "mbm_total_bytes:*=e" > /sys/fs/resctrl/mbm_L3_assignments
+  # cat /sys/fs/resctrl/mbm_L3_assignments
+  mbm_total_bytes:0=e;1=e
+  mbm_local_bytes:0=e;1=e
+
+h. Read the events mbm_total_bytes and mbm_local_bytes of the default group. There is
+no change in reading the events with the assignment.  If the event is unassigned when
+reading, then the read will come back as "Unassigned".
+::
+
+  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_total_bytes
+  779247936
+  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
+  765207488
+
+i. Check the default event configurations.
+::
+
+  # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter
+  local_reads,remote_reads,local_non_temporal_writes,remote_non_temporal_writes,
+  local_reads_slow_memory,remote_reads_slow_memory,dirty_victim_writes_all
+
+  # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_local_bytes/event_filter
+  local_reads,local_non_temporal_writes,local_reads_slow_memory
+
+j. Change the event configuration for mbm_local_bytes.
+::
+
+  # echo "local_reads, local_non_temporal_writes, local_reads_slow_memory, remote_reads" >
+  /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter
+
+  # cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter
+  local_reads,local_non_temporal_writes,local_reads_slow_memory,remote_reads
+
+This will update all (across all domains of all monitor groups) counter assignments
+associated with the mbm_local_bytes event.
+
+k. Now read the local event again. The first read may come back with "Unavailable"
+status. The subsequent read of mbm_local_bytes will display the current value.
+::
+
+  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
+  Unavailable
+  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
+  314101
+
+l. Users have the option to go back to 'default' mbm_assign_mode if required. This can be
+done using the following command. Note that switching the mbm_assign_mode may reset all
+the MBM counters (and thus all MBM events) of all the resctrl groups.
+::
+
+  # echo "default" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
+  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
+  mbm_event
+  [default]
+
+m. Unmount the resctrl
+::
+
+  #umount /sys/fs/resctrl/
+
 Intel RDT Errata
 ================
 
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index b42890fd937a..9881674909f2 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -403,6 +403,8 @@ bool closid_allocated(unsigned int closid);
 
 int resctrl_find_cleanest_closid(void);
 
+struct mon_evt *mbm_get_mon_event_by_name(struct rdt_resource *r, char *name);
+
 int rdtgroup_assign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
 			       struct mon_evt *mevt);
 void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index e30a867c00bb..61419849b257 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -1220,3 +1220,21 @@ void resctrl_update_cntr_allrdtgrp(struct mon_evt *mevt)
 			rdtgroup_update_cntr_event(r, crgrp, mevt->evtid);
 	}
 }
+
+/*
+ * mbm_get_mon_event_by_name() - Return the mon_evt entry for the matching
+ * event name.
+ */
+struct mon_evt *mbm_get_mon_event_by_name(struct rdt_resource *r, char *name)
+{
+	struct mon_evt *mevt;
+
+	for_each_mon_event(mevt) {
+		if (mevt->rid == r->rid && mevt->enabled &&
+		    resctrl_is_mbm_event(mevt->evtid) &&
+		    !strcmp(mevt->name, name))
+			return mevt;
+	}
+
+	return NULL;
+}
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index dc108c5db298..b26baca389bb 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -2071,6 +2071,126 @@ static int mbm_L3_assignments_show(struct kernfs_open_file *of, struct seq_file
 	return ret;
 }
 
+static int rdtgroup_modify_assign_state(char *assign, struct rdt_mon_domain *d,
+					struct rdtgroup *rdtgrp, struct mon_evt *mevt)
+{
+	int ret = 0;
+
+	if (!assign || strlen(assign) != 1)
+		return -EINVAL;
+
+	switch (*assign) {
+	case 'e':
+		ret = rdtgroup_assign_cntr_event(d, rdtgrp, mevt);
+		break;
+	case '_':
+		rdtgroup_unassign_cntr_event(d, rdtgrp, mevt);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+static int resctrl_process_assign(struct rdt_resource *r, struct rdtgroup *rdtgrp,
+				  char *event, char *tok)
+{
+	struct rdt_mon_domain *d;
+	unsigned long dom_id = 0;
+	char *dom_str, *id_str;
+	struct mon_evt *mevt;
+	int ret;
+
+	mevt = mbm_get_mon_event_by_name(r, event);
+	if (!mevt) {
+		rdt_last_cmd_printf("Invalid event %s\n", event);
+		return  -ENOENT;
+	}
+
+next:
+	if (!tok || tok[0] == '\0')
+		return 0;
+
+	/* Start processing the strings for each domain */
+	dom_str = strim(strsep(&tok, ";"));
+
+	id_str = strsep(&dom_str, "=");
+
+	/* Check for domain id '*' which means all domains */
+	if (id_str && *id_str == '*') {
+		ret = rdtgroup_modify_assign_state(dom_str, NULL, rdtgrp, mevt);
+		if (ret)
+			rdt_last_cmd_printf("Assign operation '%s:*=%s' failed\n",
+					    event, dom_str);
+		return ret;
+	} else if (!id_str || kstrtoul(id_str, 10, &dom_id)) {
+		rdt_last_cmd_puts("Missing domain id\n");
+		return -EINVAL;
+	}
+
+	/* Verify if the dom_id is valid */
+	list_for_each_entry(d, &r->mon_domains, hdr.list) {
+		if (d->hdr.id == dom_id) {
+			ret = rdtgroup_modify_assign_state(dom_str, d, rdtgrp, mevt);
+			if (ret) {
+				rdt_last_cmd_printf("Assign operation '%s:%ld=%s' failed\n",
+						    event, dom_id, dom_str);
+				return ret;
+			}
+			goto next;
+		}
+	}
+
+	rdt_last_cmd_printf("Invalid domain id %ld\n", dom_id);
+	return -EINVAL;
+}
+
+static ssize_t mbm_L3_assignments_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 rdtgroup *rdtgrp;
+	char *token, *event;
+	int ret = 0;
+
+	/* Valid input requires a trailing newline */
+	if (nbytes == 0 || buf[nbytes - 1] != '\n')
+		return -EINVAL;
+
+	buf[nbytes - 1] = '\0';
+
+	rdtgrp = rdtgroup_kn_lock_live(of->kn);
+	if (!rdtgrp) {
+		rdtgroup_kn_unlock(of->kn);
+		return -ENOENT;
+	}
+	rdt_last_cmd_clear();
+
+	if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
+		rdt_last_cmd_puts("mbm_event mode is not enabled\n");
+		rdtgroup_kn_unlock(of->kn);
+		return -EINVAL;
+	}
+
+	while ((token = strsep(&buf, "\n")) != NULL) {
+		/*
+		 * The write command follows the following format:
+		 * “<Event>:<Domain ID>=<Assignment state>”
+		 * Extract the event name first.
+		 */
+		event = strsep(&token, ":");
+
+		ret = resctrl_process_assign(r, rdtgrp, event, token);
+		if (ret)
+			break;
+	}
+
+	rdtgroup_kn_unlock(of->kn);
+
+	return ret ?: nbytes;
+}
+
 /* rdtgroup information files for one cache resource. */
 static struct rftype res_common_files[] = {
 	{
@@ -2211,9 +2331,10 @@ static struct rftype res_common_files[] = {
 	},
 	{
 		.name		= "mbm_L3_assignments",
-		.mode		= 0444,
+		.mode		= 0644,
 		.kf_ops		= &rdtgroup_kf_single_ops,
 		.seq_show	= mbm_L3_assignments_show,
+		.write		= mbm_L3_assignments_write,
 	},
 	{
 		.name		= "mbm_assign_mode",
-- 
2.34.1

Hi Babu,

On 7/8/25 3:17 PM, Babu Moger wrote:
> Enable the mbm_l3_assignments resctrl file to be used to modify counter
> assignments of CTRL_MON and MON groups when the "mbm_event" counter
> assignment mode is enabled.
> 
> The assignment modifications are done 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. When writing, '*' applies the changes
> 	   to all domains.
> 
> Assignment states:
> 
>     _ : Unassign the counter.

"the counter" -> "a counter" (user cannot control which counter is assigned)

> 
>     e : Assign the counter exclusively.

"the counter" -> "a counter"

> 
> Examples:
> 
> $ 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
> 
> To unassign the counter associated with the mbm_total_bytes event on
> domain 0:
> 
> $ echo "mbm_total_bytes:0=_" > mbm_L3_assignments
> $ cat /sys/fs/resctrl/mbm_L3_assignments
>   mbm_total_bytes:0=_;1=e
>   mbm_local_bytes:0=e;1=e
> 
> To unassign the counter associated with the mbm_total_bytes event on
> all the domains:
> 
> $ echo "mbm_total_bytes:*=_" > mbm_L3_assignments
> $ cat /sys/fs/resctrl/mbm_L3_assignments
>   mbm_total_bytes:0=_;1=_
>   mbm_local_bytes:0=e;1=e
> 
> Signed-off-by: Babu Moger <babu.moger@amd.com>
> ---

...

> ---
>  Documentation/filesystems/resctrl.rst | 146 +++++++++++++++++++++++++-
>  fs/resctrl/internal.h                 |   2 +
>  fs/resctrl/monitor.c                  |  18 ++++
>  fs/resctrl/rdtgroup.c                 | 123 +++++++++++++++++++++-
>  4 files changed, 287 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
> index 4dd1d605d6ad..2b2acb55d8b1 100644
> --- a/Documentation/filesystems/resctrl.rst
> +++ b/Documentation/filesystems/resctrl.rst
> @@ -527,7 +527,8 @@ When the "mba_MBps" mount option is used all CTRL_MON groups will also contain:
>  	Event: A valid MBM event in the
>  	       /sys/fs/resctrl/info/L3_MON/event_configs directory.
>  
> -	Domain ID: A valid domain ID.
> +	Domain ID: A valid domain ID. When writing, '*' applies the changes
> +		   to all the domains.
>  
>  	Assignment states:
>  
> @@ -544,6 +545,34 @@ When the "mba_MBps" mount option is used all CTRL_MON groups will also contain:
>  	   mbm_total_bytes:0=e;1=e
>  	   mbm_local_bytes:0=e;1=e
>  
> +	Assignments can be modified by writing to the interface.
> +
> +	Example:
> +	To unassign the counter associated with the mbm_total_bytes event on domain 0:
> +	::
> +
> +	 # echo "mbm_total_bytes:0=_" > /sys/fs/resctrl/mbm_L3_assignments
> +	 # cat /sys/fs/resctrl/mbm_L3_assignments
> +	   mbm_total_bytes:0=_;1=e
> +	   mbm_local_bytes:0=e;1=e
> +
> +	To unassign the counter associated with the mbm_total_bytes event on all the domains:
> +	::
> +
> +	 # echo "mbm_total_bytes:*=_" > /sys/fs/resctrl/mbm_L3_assignments
> +	 # cat /sys/fs/resctrl/mbm_L3_assignments
> +	   mbm_total_bytes:0=_;1=_
> +	   mbm_local_bytes:0=e;1=e
> +
> +	To assign the counter associated with the mbm_total_bytes event on all domains in

"the counter" -> "a counter" (motivation: user space cannot control which counter is assigned)

> +	exclusive mode:
> +	::
> +
> +	 # echo "mbm_total_bytes:*=e" > /sys/fs/resctrl/mbm_L3_assignments
> +	 # cat /sys/fs/resctrl/mbm_L3_assignments
> +	   mbm_total_bytes:0=e;1=e
> +	   mbm_local_bytes:0=e;1=e
> +
>  Resource allocation rules
>  -------------------------
>  
> @@ -1579,6 +1608,121 @@ View the llc occupancy snapshot::
>    # cat /sys/fs/resctrl/p1/mon_data/mon_L3_00/llc_occupancy
>    11234000
>  
> +
> +Examples on working with mbm_assign_mode
> +========================================
> +
> +a. Check if MBM counter assignment mode is supported.
> +::
> +
> +  #mount -t resctrl resctrl /sys/fs/resctrl/

"#mount" -> "# mount" (please build htmldocs to confirm everything
looks consistent)

> +
> +  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
> +  [mbm_event]
> +  default
> +
> +The "mbm_event" mode is detected and enabled.
> +
> +b. Check how many assignable counters are supported.
> +::
> +
> +  # cat /sys/fs/resctrl/info/L3_MON/num_mbm_cntrs
> +  0=32;1=32
> +
> +c. Check how many assignable counters are available for assignment in each domain.
> +::
> +
> +  # cat /sys/fs/resctrl/info/L3_MON/available_mbm_cntrs
> +  0=30;1=30
> +
> +d. To list the default group's assign states:

Please note that these steps are inconsistent. Some end with "." and some end with ":"

> +::
> +
> +  # cat /sys/fs/resctrl/mbm_L3_assignments
> +  mbm_total_bytes:0=e;1=e
> +  mbm_local_bytes:0=e;1=e
> +
> +e.  To unassign the counter associated with the mbm_total_bytes event on domain 0:
> +::
> +
> +  # echo "mbm_total_bytes:0=_" > /sys/fs/resctrl/mbm_L3_assignments
> +  # cat /sys/fs/resctrl/mbm_L3_assignments
> +  mbm_total_bytes:0=_;1=e
> +  mbm_local_bytes:0=e;1=e
> +
> +f. To unassign the counter associated with the mbm_total_bytes event on all domains:
> +::
> +
> +  # echo "mbm_total_bytes:*=_" > /sys/fs/resctrl/mbm_L3_assignments
> +  # cat /sys/fs/resctrl/mbm_L3_assignment
> +  mbm_total_bytes:0=_;1=_
> +  mbm_local_bytes:0=e;1=e
> +
> +g. To assign a counter associated with the mbm_total_bytes event on all domains in

ah ... here "a counter" is used.

> +exclusive mode:
> +::
> +
> +  # echo "mbm_total_bytes:*=e" > /sys/fs/resctrl/mbm_L3_assignments
> +  # cat /sys/fs/resctrl/mbm_L3_assignments
> +  mbm_total_bytes:0=e;1=e
> +  mbm_local_bytes:0=e;1=e
> +
> +h. Read the events mbm_total_bytes and mbm_local_bytes of the default group. There is
> +no change in reading the events with the assignment.  If the event is unassigned when
> +reading, then the read will come back as "Unassigned".

Since returning "Unassigned" can be complicated, the associated description should
probably just be done once in the doc. I expect this will be in the "mon_data" section.

> +::
> +
> +  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_total_bytes
> +  779247936
> +  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
> +  765207488
> +
> +i. Check the default event configurations.

Drop "default" (there are only these event configurations)

> +::
> +
> +  # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter
> +  local_reads,remote_reads,local_non_temporal_writes,remote_non_temporal_writes,
> +  local_reads_slow_memory,remote_reads_slow_memory,dirty_victim_writes_all
> +
> +  # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_local_bytes/event_filter
> +  local_reads,local_non_temporal_writes,local_reads_slow_memory
> +
> +j. Change the event configuration for mbm_local_bytes.
> +::
> +
> +  # echo "local_reads, local_non_temporal_writes, local_reads_slow_memory, remote_reads" >
> +  /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter

"counter_configs" -> "event_configs" (this was also an issue in previous series, please
use grep to ensure all are fixed)

> +
> +  # cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter

"counter_configs" -> "event_configs"

> +  local_reads,local_non_temporal_writes,local_reads_slow_memory,remote_reads
> +
> +This will update all (across all domains of all monitor groups) counter assignments
> +associated with the mbm_local_bytes event.
> +
> +k. Now read the local event again. The first read may come back with "Unavailable"
> +status. The subsequent read of mbm_local_bytes will display the current value.
> +::
> +
> +  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
> +  Unavailable
> +  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
> +  314101
> +
> +l. Users have the option to go back to 'default' mbm_assign_mode if required. This can be
> +done using the following command. Note that switching the mbm_assign_mode may reset all
> +the MBM counters (and thus all MBM events) of all the resctrl groups.
> +::
> +
> +  # echo "default" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
> +  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
> +  mbm_event
> +  [default]
> +
> +m. Unmount the resctrl

"Unmount the resctrl" -> "Unmount resctrl" or "Unmount the resctrl filesystem"?

> +::
> +
> +  #umount /sys/fs/resctrl/

"#umount" -> "# umount"

> +
>  Intel RDT Errata
>  ================
>  
> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
> index b42890fd937a..9881674909f2 100644
> --- a/fs/resctrl/internal.h
> +++ b/fs/resctrl/internal.h
> @@ -403,6 +403,8 @@ bool closid_allocated(unsigned int closid);
>  
>  int resctrl_find_cleanest_closid(void);
>  
> +struct mon_evt *mbm_get_mon_event_by_name(struct rdt_resource *r, char *name);
> +
>  int rdtgroup_assign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
>  			       struct mon_evt *mevt);
>  void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
> index e30a867c00bb..61419849b257 100644
> --- a/fs/resctrl/monitor.c
> +++ b/fs/resctrl/monitor.c
> @@ -1220,3 +1220,21 @@ void resctrl_update_cntr_allrdtgrp(struct mon_evt *mevt)
>  			rdtgroup_update_cntr_event(r, crgrp, mevt->evtid);
>  	}
>  }
> +
> +/*
> + * mbm_get_mon_event_by_name() - Return the mon_evt entry for the matching
> + * event name.
> + */
> +struct mon_evt *mbm_get_mon_event_by_name(struct rdt_resource *r, char *name)
> +{
> +	struct mon_evt *mevt;
> +
> +	for_each_mon_event(mevt) {
> +		if (mevt->rid == r->rid && mevt->enabled &&
> +		    resctrl_is_mbm_event(mevt->evtid) &&
> +		    !strcmp(mevt->name, name))
> +			return mevt;
> +	}
> +
> +	return NULL;
> +}
> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> index dc108c5db298..b26baca389bb 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -2071,6 +2071,126 @@ static int mbm_L3_assignments_show(struct kernfs_open_file *of, struct seq_file
>  	return ret;
>  }
>  
> +static int rdtgroup_modify_assign_state(char *assign, struct rdt_mon_domain *d,

Please move to monitor.c

> +					struct rdtgroup *rdtgrp, struct mon_evt *mevt)
> +{
> +	int ret = 0;
> +
> +	if (!assign || strlen(assign) != 1)
> +		return -EINVAL;
> +
> +	switch (*assign) {
> +	case 'e':
> +		ret = rdtgroup_assign_cntr_event(d, rdtgrp, mevt);

This patch enables the user to assign counters to multiple events in a
single write. Looking at this flow:
rdtgroup_assign_cntr_event()->rdtgroup_alloc_config_cntr() may thus
be called on the same domain but for different events in a single write from
user space.
I thus think that the error message in rdtgroup_alloc_config_cntr()
should not just contain the domain ID, but also the event *name*
(not the ID since user space cannot be expect to understand if).
considering this it seems that @mevt can be passed through
to rdtgroup_alloc_config_cntr() instead of just the event ID to support
this?

> +		break;
> +	case '_':
> +		rdtgroup_unassign_cntr_event(d, rdtgrp, mevt);
> +		break;
> +	default:
> +		ret = -EINVAL;

Please add a "break".

> +	}
> +
> +	return ret;
> +}
> +
> +static int resctrl_process_assign(struct rdt_resource *r, struct rdtgroup *rdtgrp,

Please move to monitor.c and rename to be more specific. For example, 
resctrl_parse_mbm_assignment()? Open to ideas.

> +				  char *event, char *tok)
> +{
> +	struct rdt_mon_domain *d;
> +	unsigned long dom_id = 0;
> +	char *dom_str, *id_str;
> +	struct mon_evt *mevt;
> +	int ret;
> +
> +	mevt = mbm_get_mon_event_by_name(r, event);
> +	if (!mevt) {
> +		rdt_last_cmd_printf("Invalid event %s\n", event);
> +		return  -ENOENT;
> +	}
> +
> +next:
> +	if (!tok || tok[0] == '\0')
> +		return 0;
> +
> +	/* Start processing the strings for each domain */
> +	dom_str = strim(strsep(&tok, ";"));
> +
> +	id_str = strsep(&dom_str, "=");
> +
> +	/* Check for domain id '*' which means all domains */
> +	if (id_str && *id_str == '*') {
> +		ret = rdtgroup_modify_assign_state(dom_str, NULL, rdtgrp, mevt);
> +		if (ret)
> +			rdt_last_cmd_printf("Assign operation '%s:*=%s' failed\n",
> +					    event, dom_str);
> +		return ret;
> +	} else if (!id_str || kstrtoul(id_str, 10, &dom_id)) {
> +		rdt_last_cmd_puts("Missing domain id\n");
> +		return -EINVAL;
> +	}
> +
> +	/* Verify if the dom_id is valid */
> +	list_for_each_entry(d, &r->mon_domains, hdr.list) {
> +		if (d->hdr.id == dom_id) {
> +			ret = rdtgroup_modify_assign_state(dom_str, d, rdtgrp, mevt);
> +			if (ret) {
> +				rdt_last_cmd_printf("Assign operation '%s:%ld=%s' failed\n",
> +						    event, dom_id, dom_str);
> +				return ret;
> +			}
> +			goto next;
> +		}
> +	}
> +
> +	rdt_last_cmd_printf("Invalid domain id %ld\n", dom_id);
> +	return -EINVAL;
> +}
> +
Reinette

Hi Reinette,

On 7/17/25 23:01, Reinette Chatre wrote:
> Hi Babu,
> 
> On 7/8/25 3:17 PM, Babu Moger wrote:
>> Enable the mbm_l3_assignments resctrl file to be used to modify counter
>> assignments of CTRL_MON and MON groups when the "mbm_event" counter
>> assignment mode is enabled.
>>
>> The assignment modifications are done 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. When writing, '*' applies the changes
>> 	   to all domains.
>>
>> Assignment states:
>>
>>     _ : Unassign the counter.
> 
> "the counter" -> "a counter" (user cannot control which counter is assigned)

Sure.

> 
>>
>>     e : Assign the counter exclusively.
> 
> "the counter" -> "a counter"

Sure.

> 
>>
>> Examples:
>>
>> $ 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
>>
>> To unassign the counter associated with the mbm_total_bytes event on
>> domain 0:
>>
>> $ echo "mbm_total_bytes:0=_" > mbm_L3_assignments
>> $ cat /sys/fs/resctrl/mbm_L3_assignments
>>   mbm_total_bytes:0=_;1=e
>>   mbm_local_bytes:0=e;1=e
>>
>> To unassign the counter associated with the mbm_total_bytes event on
>> all the domains:
>>
>> $ echo "mbm_total_bytes:*=_" > mbm_L3_assignments
>> $ cat /sys/fs/resctrl/mbm_L3_assignments
>>   mbm_total_bytes:0=_;1=_
>>   mbm_local_bytes:0=e;1=e
>>
>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>> ---
> 
> ...
> 
>> ---
>>  Documentation/filesystems/resctrl.rst | 146 +++++++++++++++++++++++++-
>>  fs/resctrl/internal.h                 |   2 +
>>  fs/resctrl/monitor.c                  |  18 ++++
>>  fs/resctrl/rdtgroup.c                 | 123 +++++++++++++++++++++-
>>  4 files changed, 287 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
>> index 4dd1d605d6ad..2b2acb55d8b1 100644
>> --- a/Documentation/filesystems/resctrl.rst
>> +++ b/Documentation/filesystems/resctrl.rst
>> @@ -527,7 +527,8 @@ When the "mba_MBps" mount option is used all CTRL_MON groups will also contain:
>>  	Event: A valid MBM event in the
>>  	       /sys/fs/resctrl/info/L3_MON/event_configs directory.
>>  
>> -	Domain ID: A valid domain ID.
>> +	Domain ID: A valid domain ID. When writing, '*' applies the changes
>> +		   to all the domains.
>>  
>>  	Assignment states:
>>  
>> @@ -544,6 +545,34 @@ When the "mba_MBps" mount option is used all CTRL_MON groups will also contain:
>>  	   mbm_total_bytes:0=e;1=e
>>  	   mbm_local_bytes:0=e;1=e
>>  
>> +	Assignments can be modified by writing to the interface.
>> +
>> +	Example:
>> +	To unassign the counter associated with the mbm_total_bytes event on domain 0:
>> +	::
>> +
>> +	 # echo "mbm_total_bytes:0=_" > /sys/fs/resctrl/mbm_L3_assignments
>> +	 # cat /sys/fs/resctrl/mbm_L3_assignments
>> +	   mbm_total_bytes:0=_;1=e
>> +	   mbm_local_bytes:0=e;1=e
>> +
>> +	To unassign the counter associated with the mbm_total_bytes event on all the domains:
>> +	::
>> +
>> +	 # echo "mbm_total_bytes:*=_" > /sys/fs/resctrl/mbm_L3_assignments
>> +	 # cat /sys/fs/resctrl/mbm_L3_assignments
>> +	   mbm_total_bytes:0=_;1=_
>> +	   mbm_local_bytes:0=e;1=e
>> +
>> +	To assign the counter associated with the mbm_total_bytes event on all domains in
> 
> "the counter" -> "a counter" (motivation: user space cannot control which counter is assigned)

Sure.

> 
>> +	exclusive mode:
>> +	::
>> +
>> +	 # echo "mbm_total_bytes:*=e" > /sys/fs/resctrl/mbm_L3_assignments
>> +	 # cat /sys/fs/resctrl/mbm_L3_assignments
>> +	   mbm_total_bytes:0=e;1=e
>> +	   mbm_local_bytes:0=e;1=e
>> +
>>  Resource allocation rules
>>  -------------------------
>>  
>> @@ -1579,6 +1608,121 @@ View the llc occupancy snapshot::
>>    # cat /sys/fs/resctrl/p1/mon_data/mon_L3_00/llc_occupancy
>>    11234000
>>  
>> +
>> +Examples on working with mbm_assign_mode
>> +========================================
>> +
>> +a. Check if MBM counter assignment mode is supported.
>> +::
>> +
>> +  #mount -t resctrl resctrl /sys/fs/resctrl/
> 
> "#mount" -> "# mount" (please build htmldocs to confirm everything
> looks consistent)

Sure.

> 
>> +
>> +  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
>> +  [mbm_event]
>> +  default
>> +
>> +The "mbm_event" mode is detected and enabled.
>> +
>> +b. Check how many assignable counters are supported.
>> +::
>> +
>> +  # cat /sys/fs/resctrl/info/L3_MON/num_mbm_cntrs
>> +  0=32;1=32
>> +
>> +c. Check how many assignable counters are available for assignment in each domain.
>> +::
>> +
>> +  # cat /sys/fs/resctrl/info/L3_MON/available_mbm_cntrs
>> +  0=30;1=30
>> +
>> +d. To list the default group's assign states:
> 
> Please note that these steps are inconsistent. Some end with "." and some end with ":"

Fixed it.

> 
>> +::
>> +
>> +  # cat /sys/fs/resctrl/mbm_L3_assignments
>> +  mbm_total_bytes:0=e;1=e
>> +  mbm_local_bytes:0=e;1=e
>> +
>> +e.  To unassign the counter associated with the mbm_total_bytes event on domain 0:
>> +::
>> +
>> +  # echo "mbm_total_bytes:0=_" > /sys/fs/resctrl/mbm_L3_assignments
>> +  # cat /sys/fs/resctrl/mbm_L3_assignments
>> +  mbm_total_bytes:0=_;1=e
>> +  mbm_local_bytes:0=e;1=e
>> +
>> +f. To unassign the counter associated with the mbm_total_bytes event on all domains:
>> +::
>> +
>> +  # echo "mbm_total_bytes:*=_" > /sys/fs/resctrl/mbm_L3_assignments
>> +  # cat /sys/fs/resctrl/mbm_L3_assignment
>> +  mbm_total_bytes:0=_;1=_
>> +  mbm_local_bytes:0=e;1=e
>> +
>> +g. To assign a counter associated with the mbm_total_bytes event on all domains in
> 
> ah ... here "a counter" is used.
> 
>> +exclusive mode:
>> +::
>> +
>> +  # echo "mbm_total_bytes:*=e" > /sys/fs/resctrl/mbm_L3_assignments
>> +  # cat /sys/fs/resctrl/mbm_L3_assignments
>> +  mbm_total_bytes:0=e;1=e
>> +  mbm_local_bytes:0=e;1=e
>> +
>> +h. Read the events mbm_total_bytes and mbm_local_bytes of the default group. There is
>> +no change in reading the events with the assignment.  If the event is unassigned when
>> +reading, then the read will come back as "Unassigned".
> 
> Since returning "Unassigned" can be complicated, the associated description should
> probably just be done once in the doc. I expect this will be in the "mon_data" section.

Addressed with
https://lore.kernel.org/lkml/2c107793-1258-4276-8b29-03359fa605f2@amd.com/

> 
>> +::
>> +
>> +  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_total_bytes
>> +  779247936
>> +  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
>> +  765207488
>> +
>> +i. Check the default event configurations.
> 
> Drop "default" (there are only these event configurations)
> 

Sure.

>> +::
>> +
>> +  # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter
>> +  local_reads,remote_reads,local_non_temporal_writes,remote_non_temporal_writes,
>> +  local_reads_slow_memory,remote_reads_slow_memory,dirty_victim_writes_all
>> +
>> +  # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_local_bytes/event_filter
>> +  local_reads,local_non_temporal_writes,local_reads_slow_memory
>> +
>> +j. Change the event configuration for mbm_local_bytes.
>> +::
>> +
>> +  # echo "local_reads, local_non_temporal_writes, local_reads_slow_memory, remote_reads" >
>> +  /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter
> 
> "counter_configs" -> "event_configs" (this was also an issue in previous series, please
> use grep to ensure all are fixed)

Fixed.

> 
>> +
>> +  # cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter
> 
> "counter_configs" -> "event_configs"
> 
Sure.

>> +  local_reads,local_non_temporal_writes,local_reads_slow_memory,remote_reads
>> +
>> +This will update all (across all domains of all monitor groups) counter assignments
>> +associated with the mbm_local_bytes event.
>> +
>> +k. Now read the local event again. The first read may come back with "Unavailable"
>> +status. The subsequent read of mbm_local_bytes will display the current value.
>> +::
>> +
>> +  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
>> +  Unavailable
>> +  # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
>> +  314101
>> +
>> +l. Users have the option to go back to 'default' mbm_assign_mode if required. This can be
>> +done using the following command. Note that switching the mbm_assign_mode may reset all
>> +the MBM counters (and thus all MBM events) of all the resctrl groups.
>> +::
>> +
>> +  # echo "default" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
>> +  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
>> +  mbm_event
>> +  [default]
>> +
>> +m. Unmount the resctrl
> 
> "Unmount the resctrl" -> "Unmount resctrl" or "Unmount the resctrl filesystem"?

Changed to "Unmount the resctrl filesystem."
> 
>> +::
>> +
>> +  #umount /sys/fs/resctrl/
> 
> "#umount" -> "# umount"
> 

Sure.

>> +
>>  Intel RDT Errata
>>  ================
>>  
>> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
>> index b42890fd937a..9881674909f2 100644
>> --- a/fs/resctrl/internal.h
>> +++ b/fs/resctrl/internal.h
>> @@ -403,6 +403,8 @@ bool closid_allocated(unsigned int closid);
>>  
>>  int resctrl_find_cleanest_closid(void);
>>  
>> +struct mon_evt *mbm_get_mon_event_by_name(struct rdt_resource *r, char *name);
>> +
>>  int rdtgroup_assign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
>>  			       struct mon_evt *mevt);
>>  void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
>> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
>> index e30a867c00bb..61419849b257 100644
>> --- a/fs/resctrl/monitor.c
>> +++ b/fs/resctrl/monitor.c
>> @@ -1220,3 +1220,21 @@ void resctrl_update_cntr_allrdtgrp(struct mon_evt *mevt)
>>  			rdtgroup_update_cntr_event(r, crgrp, mevt->evtid);
>>  	}
>>  }
>> +
>> +/*
>> + * mbm_get_mon_event_by_name() - Return the mon_evt entry for the matching
>> + * event name.
>> + */
>> +struct mon_evt *mbm_get_mon_event_by_name(struct rdt_resource *r, char *name)
>> +{
>> +	struct mon_evt *mevt;
>> +
>> +	for_each_mon_event(mevt) {
>> +		if (mevt->rid == r->rid && mevt->enabled &&
>> +		    resctrl_is_mbm_event(mevt->evtid) &&
>> +		    !strcmp(mevt->name, name))
>> +			return mevt;
>> +	}
>> +
>> +	return NULL;
>> +}
>> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
>> index dc108c5db298..b26baca389bb 100644
>> --- a/fs/resctrl/rdtgroup.c
>> +++ b/fs/resctrl/rdtgroup.c
>> @@ -2071,6 +2071,126 @@ static int mbm_L3_assignments_show(struct kernfs_open_file *of, struct seq_file
>>  	return ret;
>>  }
>>  
>> +static int rdtgroup_modify_assign_state(char *assign, struct rdt_mon_domain *d,
> 
> Please move to monitor.c

Sure.

> 
>> +					struct rdtgroup *rdtgrp, struct mon_evt *mevt)
>> +{
>> +	int ret = 0;
>> +
>> +	if (!assign || strlen(assign) != 1)
>> +		return -EINVAL;
>> +
>> +	switch (*assign) {
>> +	case 'e':
>> +		ret = rdtgroup_assign_cntr_event(d, rdtgrp, mevt);
> 
> This patch enables the user to assign counters to multiple events in a
> single write. Looking at this flow:
> rdtgroup_assign_cntr_event()->rdtgroup_alloc_config_cntr() may thus
> be called on the same domain but for different events in a single write from
> user space.
> I thus think that the error message in rdtgroup_alloc_config_cntr()
> should not just contain the domain ID, but also the event *name*
> (not the ID since user space cannot be expect to understand if).
> considering this it seems that @mevt can be passed through
> to rdtgroup_alloc_config_cntr() instead of just the event ID to support
> this?

Yes. Taken care.

> 
>> +		break;
>> +	case '_':
>> +		rdtgroup_unassign_cntr_event(d, rdtgrp, mevt);
>> +		break;
>> +	default:
>> +		ret = -EINVAL;
> 
> Please add a "break".
> 

Sure.

>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static int resctrl_process_assign(struct rdt_resource *r, struct rdtgroup *rdtgrp,
> 
> Please move to monitor.c and rename to be more specific. For example, 
> resctrl_parse_mbm_assignment()? Open to ideas.

Sure. Fine with resctrl_parse_mbm_assignment().

> 
>> +				  char *event, char *tok)
>> +{
>> +	struct rdt_mon_domain *d;
>> +	unsigned long dom_id = 0;
>> +	char *dom_str, *id_str;
>> +	struct mon_evt *mevt;
>> +	int ret;
>> +
>> +	mevt = mbm_get_mon_event_by_name(r, event);
>> +	if (!mevt) {
>> +		rdt_last_cmd_printf("Invalid event %s\n", event);
>> +		return  -ENOENT;
>> +	}
>> +
>> +next:
>> +	if (!tok || tok[0] == '\0')
>> +		return 0;
>> +
>> +	/* Start processing the strings for each domain */
>> +	dom_str = strim(strsep(&tok, ";"));
>> +
>> +	id_str = strsep(&dom_str, "=");
>> +
>> +	/* Check for domain id '*' which means all domains */
>> +	if (id_str && *id_str == '*') {
>> +		ret = rdtgroup_modify_assign_state(dom_str, NULL, rdtgrp, mevt);
>> +		if (ret)
>> +			rdt_last_cmd_printf("Assign operation '%s:*=%s' failed\n",
>> +					    event, dom_str);
>> +		return ret;
>> +	} else if (!id_str || kstrtoul(id_str, 10, &dom_id)) {
>> +		rdt_last_cmd_puts("Missing domain id\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	/* Verify if the dom_id is valid */
>> +	list_for_each_entry(d, &r->mon_domains, hdr.list) {
>> +		if (d->hdr.id == dom_id) {
>> +			ret = rdtgroup_modify_assign_state(dom_str, d, rdtgrp, mevt);
>> +			if (ret) {
>> +				rdt_last_cmd_printf("Assign operation '%s:%ld=%s' failed\n",
>> +						    event, dom_id, dom_str);
>> +				return ret;
>> +			}
>> +			goto next;
>> +		}
>> +	}
>> +
>> +	rdt_last_cmd_printf("Invalid domain id %ld\n", dom_id);
>> +	return -EINVAL;
>> +}
>> +
> Reinette
> 

-- 
Thanks
Babu Moger