linux-kernel - [PATCH v2 06/17] x86/resctrl: Introduce interface to display number of ABMC counters

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Date: Fri, 19 Jan 2024 12:22:08 -0600
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>
Subject: [PATCH v2 06/17] x86/resctrl: Introduce interface to display number of ABMC counters

The ABMC feature provides an option to the user to pin (or assign) the
RMID to the hardware counter and monitor the bandwidth for a longer
duration. There are only a limited number of hardware counters.

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

Signed-off-by: Babu Moger <babu.moger@....com>

---
v2: Changed the field name to mbm_assignable_counters from abmc_counters.
---
 Documentation/arch/x86/resctrl.rst     |  4 ++++
 arch/x86/kernel/cpu/resctrl/monitor.c  |  4 ++++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 17 +++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index ecc6c65bdaca..73eeb50fd0b5 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -264,6 +264,10 @@ with the following files:
 	    # cat /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config
 	    0=0x30;1=0x30;3=0x15;4=0x15
 
+"mbm_assignable_counters":
+	Available when ABMC feature is supported. The number of assignable bandwidth
+	monitoring counters available.
+
 "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 a6c336b6de61..fa492ea820f0 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -823,6 +823,10 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 			resctrl_file_fflags_init("mbm_local_bytes_config",
 						 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
 		}
+
+		if (rdt_cpu_has(X86_FEATURE_ABMC))
+			resctrl_file_fflags_init("mbm_assignable_counters",
+						 RFTYPE_MON_INFO);
 	}
 
 	l3_mon_evt_init(r);
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 3e233251e7ed..53be5cd1c28e 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -811,6 +811,17 @@ static int rdtgroup_rmid_show(struct kernfs_open_file *of,
 	return ret;
 }
 
+static int rdtgroup_mbm_assignable_counters_show(struct kernfs_open_file *of,
+						 struct seq_file *s, void *v)
+{
+	struct rdt_resource *r = of->kn->parent->priv;
+	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
+
+	seq_printf(s, "%d\n", hw_res->mbm_assignable_counters);
+
+	return 0;
+}
+
 #ifdef CONFIG_PROC_CPU_RESCTRL
 
 /*
@@ -1861,6 +1872,12 @@ static struct rftype res_common_files[] = {
 		.seq_show	= mbm_local_bytes_config_show,
 		.write		= mbm_local_bytes_config_write,
 	},
+	{
+		.name		= "mbm_assignable_counters",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdtgroup_mbm_assignable_counters_show,
+	},
 	{
 		.name		= "cpus",
 		.mode		= 0644,
-- 
2.34.1