linux-kernel - [PATCH v5 08/20] x86/resctrl: Introduce interface to display number of monitoring counters

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Message-ID: <dc6716ae485cdd442057360f4619582a9c4b34a5.1720043311.git.babu.moger@amd.com>
Date: Wed, 3 Jul 2024 16:48:19 -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>,
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	<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 08/20] x86/resctrl: Introduce interface to display number of monitoring counters

The ABMC feature provides an option to the user to assign a hardware
counter to an RMID and monitor the bandwidth as long as the counter is
assigned. Number of assignments depend on number of monitoring counters
available.

Provide the interface to display the number of monitoring counters
supported.

Signed-off-by: Babu Moger <babu.moger@....com>
---
v5: Changed the display name from num_cntrs to num_mbm_cntrs.
    Updated the commit message.
    Moved the patch after mbm_mode is introduced.

v4: Changed the counter name to num_cntrs. And few text changes.

v3: Changed the field name to mbm_assign_cntrs.

v2: Changed the field name to mbm_assignable_counters from abmc_counters.
---
 Documentation/arch/x86/resctrl.rst     |  3 +++
 arch/x86/kernel/cpu/resctrl/monitor.c  |  2 ++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 16 ++++++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 108e494fd7cc..4907d0758118 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -287,6 +287,9 @@ with the following files:
 	Without ABMC enabled, monitoring will work in "legacy" mode
 	without assignment option.
 
+"num_mbm_cntrs":
+	The number of monitoring counters available for assignment.
+
 "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/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 6c4cb36b4b50..7a93a6d2b2de 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -1242,6 +1242,8 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 			r->mon.num_mbm_cntrs = (ebx & 0xFFFF) + 1;
 			if (WARN_ON(r->mon.num_mbm_cntrs > 64))
 				r->mon.num_mbm_cntrs = 64;
+
+			resctrl_file_fflags_init("num_mbm_cntrs", RFTYPE_MON_INFO);
 		}
 	}
 
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 3988d7b86817..4f47f52e01c2 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -865,6 +865,16 @@ static int rdtgroup_mbm_mode_show(struct kernfs_open_file *of,
 	return 0;
 }
 
+static int rdtgroup_num_mbm_cntrs_show(struct kernfs_open_file *of,
+				       struct seq_file *s, void *v)
+{
+	struct rdt_resource *r = of->kn->parent->priv;
+
+	seq_printf(s, "%d\n", r->mon.num_mbm_cntrs);
+
+	return 0;
+}
+
 #ifdef CONFIG_PROC_CPU_RESCTRL
 
 /*
@@ -1935,6 +1945,12 @@ static struct rftype res_common_files[] = {
 		.seq_show	= rdtgroup_cpus_show,
 		.fflags		= RFTYPE_BASE,
 	},
+	{
+		.name		= "num_mbm_cntrs",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdtgroup_num_mbm_cntrs_show,
+	},
 	{
 		.name		= "cpus_list",
 		.mode		= 0644,
-- 
2.34.1