In mbm_cntr_assign mode, the hardware counter should be assigned to read
the MBM events.
Report "Unassigned" in case the user attempts to read the events without
assigning the counter.
Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
v9: Used is_mbm_event() to check the event type.
Minor user documentation update.
v8: Used MBM_EVENT_ARRAY_INDEX to get the index for the MBM event.
Documentation update to make the text generic.
v7: Moved the documentation under "mon_data".
Updated the text little bit.
v6: Added more explaination in the resctrl.rst
Added checks to detect "Unassigned" before reading RMID.
v5: New patch.
---
Documentation/arch/x86/resctrl.rst | 10 ++++++++++
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 12 +++++++++++-
2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 2bc58d974934..864fc004d646 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -430,6 +430,16 @@ When monitoring is enabled all MON groups will also contain:
for the L3 cache they occupy). These are named "mon_sub_L3_YY"
where "YY" is the node number.
+ When supported the 'mbm_cntr_assign' mode allows users to assign a
+ counter to mon_hw_id, event pair enabling bandwidth monitoring for
+ as long as the counter remains assigned. The hardware will continue
+ tracking the assigned mon_hw_id until the user manually unassigns
+ it, ensuring that counters are not reset during this period. With
+ a limited number of counters, the system may run out of assignable
+ counters. In that case, MBM event counters will return "Unassigned"
+ when the event is read. Users must manually assign a counter to read
+ the events.
+
"mon_hw_id":
Available only with debug option. The identifier used by hardware
for the monitor group. On x86 this is the RMID.
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 200d89a64027..43a48943578f 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -567,7 +567,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
struct rdtgroup *rdtgrp;
struct rdt_resource *r;
union mon_data_bits md;
- int ret = 0;
+ int ret = 0, index;
rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (!rdtgrp) {
@@ -581,6 +581,14 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
evtid = md.u.evtid;
r = &rdt_resources_all[resid].r_resctrl;
+ if (resctrl_arch_mbm_cntr_assign_enabled(r) && is_mbm_event(evtid)) {
+ index = MBM_EVENT_ARRAY_INDEX(evtid);
+ if (rdtgrp->mon.cntr_id[index] == MON_CNTR_UNSET) {
+ rr.err = -ENOENT;
+ goto checkresult;
+ }
+ }
+
if (md.u.sum) {
/*
* This file requires summing across all domains that share
@@ -618,6 +626,8 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
seq_puts(m, "Error\n");
else if (rr.err == -EINVAL)
seq_puts(m, "Unavailable\n");
+ else if (rr.err == -ENOENT)
+ seq_puts(m, "Unassigned\n");
else
seq_printf(m, "%llu\n", rr.val);
--
2.34.1
