[PATCH v3 07/10] x86/resctrl: Add sysfs interface files to read/write event configuration

From: Babu Moger
Date: Mon Aug 22 2022 - 09:44:36 EST


Add two new sysfs files to read/write the event configuration if
the feature Bandwidth Monitoring Event Configuration (BMEC) is
supported. The file mbm_local_config is for the configuration
of the event mbm_local_bytes and the file mbm_total_config is
for the configuration of mbm_total_bytes.

$ls /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local*
/sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
/sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_config

$ls /sys/fs/resctrl/mon_data/mon_L3_00/mbm_total*
/sys/fs/resctrl/mon_data/mon_L3_00/mbm_total_bytes
/sys/fs/resctrl/mon_data/mon_L3_00/mbm_total_config

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/kernel/cpu/resctrl/internal.h | 3 +++
arch/x86/kernel/cpu/resctrl/monitor.c | 2 ++
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 32 ++++++++++++++++++++++++++++++++
3 files changed, 37 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index c049a274383c..fc725f5e9024 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -72,11 +72,13 @@ DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
* struct mon_evt - Entry in the event list of a resource
* @evtid: event id
* @name: name of the event
+ * @config: current configuration
* @list: entry in &rdt_resource->evt_list
*/
struct mon_evt {
u32 evtid;
char *name;
+ char *config;
struct list_head list;
};

@@ -95,6 +97,7 @@ union mon_data_bits {
unsigned int rid : 10;
unsigned int evtid : 8;
unsigned int domid : 14;
+ unsigned int mon_config : 32;
} u;
};

diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index b9de417dac1c..3f900241dbab 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -656,11 +656,13 @@ static struct mon_evt llc_occupancy_event = {
static struct mon_evt mbm_total_event = {
.name = "mbm_total_bytes",
.evtid = QOS_L3_MBM_TOTAL_EVENT_ID,
+ .config = "mbm_total_config",
};

static struct mon_evt mbm_local_event = {
.name = "mbm_local_bytes",
.evtid = QOS_L3_MBM_LOCAL_EVENT_ID,
+ .config = "mbm_local_config",
};

/*
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 855483b297a8..30d2182d4fda 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -254,6 +254,10 @@ static const struct kernfs_ops kf_mondata_ops = {
.seq_show = rdtgroup_mondata_show,
};

+static const struct kernfs_ops kf_mondata_config_ops = {
+ .atomic_write_len = PAGE_SIZE,
+};
+
static bool is_cpu_list(struct kernfs_open_file *of)
{
struct rftype *rft = of->kn->priv;
@@ -2534,6 +2538,25 @@ void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r, unsigned int dom_id)
}
}

+static int mon_config_addfile(struct kernfs_node *parent_kn, const char *name,
+ void *priv)
+{
+ struct kernfs_node *kn;
+ int ret = 0;
+
+ kn = __kernfs_create_file(parent_kn, name, 0644,
+ GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, 0,
+ &kf_mondata_config_ops, priv, NULL, NULL);
+ if (IS_ERR(kn))
+ return PTR_ERR(kn);
+
+ ret = rdtgroup_kn_set_ugid(kn);
+ if (ret)
+ kernfs_remove(kn);
+
+ return ret;
+}
+
static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
struct rdt_domain *d,
struct rdt_resource *r, struct rdtgroup *prgrp)
@@ -2568,6 +2591,15 @@ static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
if (ret)
goto out_destroy;

+ /* Create the sysfs event configuration files */
+ if (r->mon_configurable &&
+ (mevt->evtid == QOS_L3_MBM_TOTAL_EVENT_ID ||
+ mevt->evtid == QOS_L3_MBM_LOCAL_EVENT_ID)) {
+ ret = mon_config_addfile(kn, mevt->config, priv.priv);
+ if (ret)
+ goto out_destroy;
+ }
+
if (is_mbm_event(mevt->evtid))
mon_event_read(&rr, r, d, prgrp, mevt->evtid, true);
}