In ABMC 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>
---
v6: Added more explaination in the resctrl.rst
Added checks to detect "Unassigned" before reading RMID.
v5: New patch.
---
Documentation/arch/x86/resctrl.rst | 11 +++++++++++
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 13 ++++++++++++-
2 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index fe9f10766c4f..aea440ee6107 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -294,6 +294,17 @@ with the following files:
"num_mbm_cntrs":
The number of monitoring counters available for assignment.
+ Resctrl subsystem provides the interface to count maximum of two
+ MBM events per group, from a combination of total and local events.
+ Keeping the current interface, users can assign a maximum of two
+ monitoring counters per group. User will also have the option to
+ enable only one counter to the group.
+
+ With limited number of counters, system can run out of assignable counters.
+ In mbm_cntr_assign mode, the MBM event counters will return "Unassigned" if
+ the counter is not assigned to the event when read. Users need to assign a
+ counter manually to read the events.
+
"max_threshold_occupancy":
Read/write file provides the largest value (in
bytes) at which a previously used LLC_occupancy
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 50fa1fe9a073..ea918ce7c3ef 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_get_abmc_enabled() && 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
