linux-kernel - [PATCH v2 08/17] x86/resctrl: Introduce the interface to display ABMC state

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Date: Fri, 19 Jan 2024 12:22:10 -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 08/17] x86/resctrl: Introduce the interface to display ABMC state

The ABMC feature provides an option to the user to assign an RMID
to the hardware counter and monitor the bandwidth for a longer duration.
System can be in only one mode at a time (Legacy Monitor mode or ABMC
mode). By default, ABMC mode is disabled.

Provide an interface to display the monitor mode on the system.
    $cat /sys/fs/resctrl/info/L3_MON/mbm_assign_enable
    0

Signed-off-by: Babu Moger <babu.moger@....com>
---
v2: This is new patch to display ABMC mode.
---
 Documentation/arch/x86/resctrl.rst     |  6 ++++++
 arch/x86/kernel/cpu/resctrl/monitor.c  |  5 ++++-
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 17 +++++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 73eeb50fd0b5..f94a4d314690 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -268,6 +268,12 @@ with the following files:
 	Available when ABMC feature is supported. The number of assignable bandwidth
 	monitoring counters available.
 
+"mbm_assign_enable":
+	Available when ABMC feature is supported. System supports RMID counter
+	assignment for monitoring. Feature provides an option to assign the RMID
+	to the hardware counter and monitor the bandwidth for a longer duration.
+	The assigned RMID will be active until the user unassigns it.
+
 "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 fa492ea820f0..a45084e30738 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -824,9 +824,12 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 						 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
 		}
 
-		if (rdt_cpu_has(X86_FEATURE_ABMC))
+		if (rdt_cpu_has(X86_FEATURE_ABMC)) {
 			resctrl_file_fflags_init("mbm_assignable_counters",
 						 RFTYPE_MON_INFO);
+			resctrl_file_fflags_init("mbm_assign_enable",
+						 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 2fb26227cbec..4f160dbf6376 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -822,6 +822,17 @@ static int rdtgroup_mbm_assignable_counters_show(struct kernfs_open_file *of,
 	return 0;
 }
 
+static int rdtgroup_mbm_assign_enable_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->abmc_enabled);
+
+	return 0;
+}
+
 #ifdef CONFIG_PROC_CPU_RESCTRL
 
 /*
@@ -1878,6 +1889,12 @@ static struct rftype res_common_files[] = {
 		.kf_ops		= &rdtgroup_kf_single_ops,
 		.seq_show	= rdtgroup_mbm_assignable_counters_show,
 	},
+	{
+		.name		= "mbm_assign_enable",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdtgroup_mbm_assign_enable_show,
+	},
 	{
 		.name		= "cpus",
 		.mode		= 0644,
-- 
2.34.1