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>
---
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 | 13 ++++++++++++-
2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 3e9302971faf..ff5397d19704 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -417,6 +417,16 @@ 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.
+ The mbm_cntr_assign mode allows users to assign a hardware counter
+ to an RMID-event pair, enabling bandwidth monitoring for as long
+ as the counter remains assigned. The hardware will continue tracking
+ the assigned RMID 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 resources. In
+ mbm_cntr_assign mode, MBM event counters will return "Unassigned"
+ if the counter is not allocated to the event when 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 50fa1fe9a073..fc19b1d131b2 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -562,7 +562,7 @@ 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) {
@@ -576,6 +576,15 @@ 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) && evtid != QOS_L3_OCCUP_EVENT_ID) {
+ index = mon_event_config_index_get(evtid);
+ if (index != INVALID_CONFIG_INDEX &&
+ 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
@@ -613,6 +622,8 @@ 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
