[PATCH v8 10/13] x86/resctrl: Add sysfs interface to write mbm_total_bytes_config

[Babu Moger]

The current event configuration for mbm_total_bytes can be changed by
the user by writing to the file
/sys/fs/resctrl/info/L3_MON/mbm_total_bytes_config.

The event configuration settings are domain specific and will affect all
the CPUs in the domain.

Following are the types of events supported:

====  ===========================================================
Bits   Description
====  ===========================================================
6      Dirty Victims from the QOS domain to all types of memory
5      Reads to slow memory in the non-local NUMA domain
4      Reads to slow memory in the local NUMA domain
3      Non-temporal writes to non-local NUMA domain
2      Non-temporal writes to local NUMA domain
1      Reads to memory in the non-local NUMA domain
0      Reads to memory in the local NUMA domain
====  ===========================================================

For example:
To change the mbm_total_bytes to count only reads on domain 0, the bits
0, 1, 4 and 5 needs to be set, which is 110011b (in hex 0x33). Run the
command.
	$echo  0=0x33 > /sys/fs/resctrl/info/L3_MON/mbm_total_bytes_config

To change the mbm_total_bytes to count all the slow memory reads on
domain 1, the bits 4 and 5 needs to be set which is 110000b (in hex 0x30).
Run the command.
	$echo  1=0x30 > /sys/fs/resctrl/info/L3_MON/mbm_total_bytes_config

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c |  130 ++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 18f9588a41cf..0cdccb69386e 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1505,6 +1505,133 @@ static int mbm_local_bytes_config_show(struct kernfs_open_file *of,
 	return 0;
 }
 
+static void mon_event_config_write(void *info)
+{
+	struct mon_config_info *mon_info = info;
+	u32 index;
+
+	index = mon_event_config_index_get(mon_info->evtid);
+	if (index >= MAX_CONFIG_EVENTS) {
+		pr_warn_once("Invalid event id %d\n", mon_info->evtid);
+		return;
+	}
+	wrmsr(MSR_IA32_EVT_CFG_BASE + index, mon_info->mon_config, 0);
+}
+
+static int mbm_config_write(struct rdt_resource *r, struct rdt_domain *d,
+			    u32 evtid, u32 val)
+{
+	struct mon_config_info mon_info = {0};
+	int ret = 0;
+
+	rdt_last_cmd_clear();
+
+	/* mon_config cannot be more than the supported set of events */
+	if (val > MAX_EVT_CONFIG_BITS) {
+		rdt_last_cmd_puts("Invalid event configuration\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Read the current config value first. If both are same then
+	 * we don't need to write it again.
+	 */
+	mon_info.evtid = evtid;
+	mondata_config_read(d, &mon_info);
+	if (mon_info.mon_config == val)
+		goto write_exit;
+
+	mon_info.mon_config = val;
+
+	/*
+	 * Update MSR_IA32_EVT_CFG_BASE MSRs on all the CPUs in the
+	 * domain. The MSRs offset from MSR MSR_IA32_EVT_CFG_BASE
+	 * are scoped at the domain level. Writing any of these MSRs
+	 * on one CPU is supposed to be observed by all CPUs in the
+	 * domain. However, the hardware team recommends to update
+	 * these MSRs on all the CPUs in the domain.
+	 */
+	on_each_cpu_mask(&d->cpu_mask, mon_event_config_write, &mon_info, 1);
+
+	/*
+	 * When an Event Configuration is changed, the bandwidth counters
+	 * for all RMIDs and Events will be cleared by the hardware. The
+	 * hardware also sets MSR_IA32_QM_CTR.Unavailable (bit 62) for
+	 * every RMID on the next read to any event for every RMID.
+	 * Subsequent reads will have MSR_IA32_QM_CTR.Unavailable (bit 62)
+	 * cleared while it is tracked by the hardware. Clear the
+	 * mbm_local and mbm_total counts for all the RMIDs.
+	 */
+	memset(d->mbm_local, 0, sizeof(struct mbm_state) * r->num_rmid);
+	memset(d->mbm_total, 0, sizeof(struct mbm_state) * r->num_rmid);
+
+write_exit:
+	return ret;
+}
+
+static int mon_config_parse(struct rdt_resource *r, char *tok, u32 evtid)
+{
+	char *dom_str = NULL, *id_str;
+	unsigned long dom_id, val;
+	struct rdt_domain *d;
+	int ret = 0;
+
+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, "=");
+
+	if (!dom_str || kstrtoul(id_str, 10, &dom_id)) {
+		rdt_last_cmd_puts("Missing '=' or non-numeric domain id\n");
+		return -EINVAL;
+	}
+
+	if (!dom_str || kstrtoul(dom_str, 16, &val)) {
+		rdt_last_cmd_puts("Missing '=' or non-numeric event configuration value\n");
+		return -EINVAL;
+	}
+
+	list_for_each_entry(d, &r->domains, list) {
+		if (d->id == dom_id) {
+			ret = mbm_config_write(r, d, evtid, val);
+			if (ret)
+				return -EINVAL;
+			goto next;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static ssize_t mbm_total_bytes_config_write(struct kernfs_open_file *of,
+					    char *buf, size_t nbytes,
+					    loff_t off)
+{
+	struct rdt_resource *r = of->kn->parent->priv;
+	int ret;
+
+	/* Valid input requires a trailing newline */
+	if (nbytes == 0 || buf[nbytes - 1] != '\n')
+		return -EINVAL;
+
+	cpus_read_lock();
+	mutex_lock(&rdtgroup_mutex);
+
+	rdt_last_cmd_clear();
+
+	buf[nbytes - 1] = '\0';
+
+	ret = mon_config_parse(r, buf, QOS_L3_MBM_TOTAL_EVENT_ID);
+
+	mutex_unlock(&rdtgroup_mutex);
+	cpus_read_unlock();
+
+	return ret ?: nbytes;
+}
+
 /* rdtgroup information files for one cache resource. */
 static struct rftype res_common_files[] = {
 	{
@@ -1605,9 +1732,10 @@ static struct rftype res_common_files[] = {
 	},
 	{
 		.name		= "mbm_total_bytes_config",
-		.mode		= 0444,
+		.mode		= 0644,
 		.kf_ops		= &rdtgroup_kf_single_ops,
 		.seq_show	= mbm_total_bytes_config_show,
+		.write		= mbm_total_bytes_config_write,
 	},
 	{
 		.name		= "mbm_local_bytes_config",