linux-kernel - [PATCH v5 16/20] x86/resctrl: Report "Unassigned" for MBM events in ABMC mode

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Message-ID: <81ca60c0029ba63fab7cfd6903ad115fad1d29fc.1720043311.git.babu.moger@amd.com>
Date: Wed, 3 Jul 2024 16:48:27 -0500
From: Babu Moger <babu.moger@....com>
To: <corbet@....net>, <fenghua.yu@...el.com>, <reinette.chatre@...el.com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>
CC: <x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
	<rdunlap@...radead.org>, <tj@...nel.org>, <peterz@...radead.org>,
	<yanjiewtw@...il.com>, <babu.moger@....com>, <kim.phillips@....com>,
	<lukas.bulwahn@...il.com>, <seanjc@...gle.com>, <jmattson@...gle.com>,
	<leitao@...ian.org>, <jpoimboe@...nel.org>, <rick.p.edgecombe@...el.com>,
	<kirill.shutemov@...ux.intel.com>, <jithu.joseph@...el.com>,
	<kai.huang@...el.com>, <kan.liang@...ux.intel.com>,
	<daniel.sneddon@...ux.intel.com>, <pbonzini@...hat.com>,
	<sandipan.das@....com>, <ilpo.jarvinen@...ux.intel.com>,
	<peternewman@...gle.com>, <maciej.wieczor-retman@...el.com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<eranian@...gle.com>, <james.morse@....com>
Subject: [PATCH v5 16/20] x86/resctrl: Report "Unassigned" for MBM events in ABMC mode

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@....com>
---
v5: New patch.
---
 Documentation/arch/x86/resctrl.rst        |  4 ++++
 arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 19 ++++++++++++++-----
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 4907d0758118..11b7a5f26b40 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -284,6 +284,10 @@ with the following files:
 	until the user unassigns it manually. There is no need to worry
 	about counters being reset during this period.
 
+	In ABMC mode, the MBM event counters will return "Unassigned" if
+	the hardware counter is not assigned to the event. Users need to
+	assign a counter manually to read the events.
+
 	Without ABMC enabled, monitoring will work in "legacy" mode
 	without assignment option.
 
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 50fa1fe9a073..e60b469b7d12 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) {
@@ -609,12 +609,21 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
 
 checkresult:
 
-	if (rr.err == -EIO)
+	if (rr.err == -EIO) {
 		seq_puts(m, "Error\n");
-	else if (rr.err == -EINVAL)
-		seq_puts(m, "Unavailable\n");
-	else
+	} else if (rr.err == -EINVAL) {
+		if (resctrl_arch_get_abmc_enabled()) {
+			index = mon_event_config_index_get(evtid);
+			if (rdtgrp->mon.cntr_id[index] == MON_CNTR_UNSET)
+				seq_puts(m, "Unassigned\n");
+			else
+				seq_puts(m, "Unavailable\n");
+		} else {
+			seq_puts(m, "Unavailable\n");
+		}
+	} else {
 		seq_printf(m, "%llu\n", rr.val);
+	}
 
 out:
 	rdtgroup_kn_unlock(of->kn);
-- 
2.34.1