[PATCH v7 09/12] x86/resctrl: Add sysfs interface to write mbm_total_bytes event configuration

Babu Moger
2022-10-17T22:28:36Z

The current event configuration can be changed by the user by writing
to the configuration file /sys/fs/resctrl/info/L3_MON/mbm_total_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_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_config

Signed-off-by: Babu Moger <babu.moger@amd.com>
---
arch/x86/kernel/cpu/resctrl/internal.h | 23 +++++
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 146 ++++++++++++++++++++++++++++++++
2 files changed, 169 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 326a1b582f38..c42b12934a0e 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -42,6 +42,29 @@
*/
#define MBM_CNTR_WIDTH_OFFSET_MAX (62 - MBM_CNTR_WIDTH_BASE)

+/* Reads to Local DRAM Memory */
+#define READS_TO_LOCAL_MEM BIT(0)
+
+/* Reads to Remote DRAM Memory */
+#define READS_TO_REMOTE_MEM BIT(1)
+
+/* Non-Temporal Writes to Local Memory */
+#define NON_TEMP_WRITE_TO_LOCAL_MEM BIT(2)
+
+/* Non-Temporal Writes to Remote Memory */
+#define NON_TEMP_WRITE_TO_REMOTE_MEM BIT(3)
+
+/* Reads to Local Memory the system identifies as "Slow Memory" */
+#define READS_TO_LOCAL_S_MEM BIT(4)
+
+/* Reads to Remote Memory the system identifies as "Slow Memory" */
+#define READS_TO_REMOTE_S_MEM BIT(5)
+
+/* Dirty Victims to All Types of Memory */
+#define DIRTY_VICTIMS_TO_ALL_MEM BIT(6)
+
+/* Max event bits supported */
+#define MAX_EVT_CONFIG_BITS GENMASK(6, 0)

struct rdt_fs_context {
struct kernfs_fs_context kfc;
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 305fb0475970..25ff56ecb817 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1494,6 +1494,151 @@ static int mbm_local_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 msr_index;
+
+ switch (mon_info->evtid) {
+ case QOS_L3_MBM_TOTAL_EVENT_ID:
+ msr_index = 0;
+ break;
+ case QOS_L3_MBM_LOCAL_EVENT_ID:
+ msr_index = 1;
+ break;
+ default:
+ /* Not expected to come here */
+ return;
+ }
+
+ wrmsr(MSR_IA32_EVT_CFG_BASE + msr_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};
+ cpumask_var_t cpu_mask;
+ int ret = 0, cpu;
+
+ 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;
+ }
+
+ cpus_read_lock();
+
+ if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL)) {
+ rdt_last_cmd_puts("cpu_mask allocation failed\n");
+ ret = -ENOMEM;
+ goto e_unlock;
+ }
+
+ /*
+ * Read the current config value first. If both are same then
+ * we dont need to write it again.
+ */
+ mon_info.evtid = evtid;
+ mondata_config_read(d, &mon_info);
+ if (mon_info.mon_config == val)
+ goto e_cpumask;
+
+ mon_info.mon_config = val;
+
+ /* Pick all the CPUs in the domain instance */
+ for_each_cpu(cpu, &d->cpu_mask)
+ cpumask_set_cpu(cpu, cpu_mask);
+
+ /*
+ * Update MSR_IA32_EVT_CFG_BASE MSRs on all the CPUs in
+ * cpu_mask. 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(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);
+
+e_cpumask:
+ free_cpumask_var(cpu_mask);
+
+e_unlock:
+ cpus_read_unlock();
+
+ return ret;
+}
+
+static int mon_config_parse(struct rdt_resource *r, char *tok, u32 evtid)
+{
+ char *dom_str = NULL, *id_str;
+ struct rdt_domain *d;
+ unsigned long dom_id, val;
+ 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_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;
+
+ rdt_last_cmd_clear();
+
+ buf[nbytes - 1] = '\0';
+
+ ret = mon_config_parse(r, buf, QOS_L3_MBM_TOTAL_EVENT_ID);
+
+ return ret ?: nbytes;
+}
+
/* rdtgroup information files for one cache resource. */
static struct rftype res_common_files[] = {
{
@@ -1597,6 +1742,7 @@ static struct rftype res_common_files[] = {
.mode = 0644,
.kf_ops = &rdtgroup_kf_single_ops,
.seq_show = mbm_total_config_show,
+ .write = mbm_total_config_write,
},
{
.name = "mbm_local_config",