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@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/r/20230113152039.770054-13-babu.moger@amd.com

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 03284a6..5990589 100644 (file)
--- 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",