[tip: x86/cache] x86/resctrl: Add interface to write mbm_local_bytes_config

[tip-bot2 for Babu Moger]

The following commit has been merged into the x86/cache branch of tip:

Commit-ID:     4fe61bff5a4100e92f81427dab06b7f3a025f6a2
Gitweb:        https://git.kernel.org/tip/4fe61bff5a4100e92f81427dab06b7f3a025f6a2
Author:        Babu Moger <babu.moger@xxxxxxx>
AuthorDate:    Fri, 13 Jan 2023 09:20:38 -06:00
Committer:     Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Mon, 23 Jan 2023 17:40:32 +01:00

x86/resctrl: Add interface to write mbm_local_bytes_config

The event configuration for mbm_local_bytes can be changed by the
user by writing to the configuration file
/sys/fs/resctrl/info/L3_MON/mbm_local_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_local_bytes_config to count all the non-temporal
writes on domain 0, the bits 2 and 3 needs to be set which is 1100b (in hex
0xc).
Run the command:

  $echo  0=0xc > /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config

To change the mbm_local_bytes to count only reads to local NUMA domain 1,
the bit 0 needs to be set which 1b (in hex 0x1). Run the command:

  $echo  1=0x1 > /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230113152039.770054-13-babu.moger@xxxxxxx
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 27 ++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 03284a6..5990589 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1638,6 +1638,30 @@ static ssize_t mbm_total_bytes_config_write(struct kernfs_open_file *of,
 	return ret ?: nbytes;
 }
 
+static ssize_t mbm_local_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;
+
+	mutex_lock(&rdtgroup_mutex);
+
+	rdt_last_cmd_clear();
+
+	buf[nbytes - 1] = '\0';
+
+	ret = mon_config_write(r, buf, QOS_L3_MBM_LOCAL_EVENT_ID);
+
+	mutex_unlock(&rdtgroup_mutex);
+
+	return ret ?: nbytes;
+}
+
 /* rdtgroup information files for one cache resource. */
 static struct rftype res_common_files[] = {
 	{
@@ -1745,9 +1769,10 @@ static struct rftype res_common_files[] = {
 	},
 	{
 		.name		= "mbm_local_bytes_config",
-		.mode		= 0444,
+		.mode		= 0644,
 		.kf_ops		= &rdtgroup_kf_single_ops,
 		.seq_show	= mbm_local_bytes_config_show,
+		.write		= mbm_local_bytes_config_write,
 	},
 	{
 		.name		= "cpus",