linux-kernel - [PATCH v2 09/17] x86/resctrl: Introdruce rdtgroup_assign_enable

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Date: Fri, 19 Jan 2024 12:22:11 -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 09/17] x86/resctrl: Introdruce rdtgroup_assign_enable_write

Introduce rdtgroup_assign_enable_write to enable ABMC mode.

Users can enable the feature by the following command.
	$echo 1 > /sys/fs/resctrl/info/L3_MON/mbm_assign_enable

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

---
v2: This is new patch to enable/disable ABMC without mounting the filesystem.
---
 Documentation/arch/x86/resctrl.rst     |  6 +++++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 34 +++++++++++++++++++++++++-
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index f94a4d314690..f09239cb93e8 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -273,6 +273,12 @@ with the following files:
 	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.
+	By default, the feature is disabled. Feature can be enabled by writing 1.
+	::
+
+	    # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_enable
+	    0
+	    # echo 1 > /sys/fs/resctrl/info/L3_MON/mbm_assign_enable
 
 "max_threshold_occupancy":
 		Read/write file provides the largest value (in
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 4f160dbf6376..9c8db9562c91 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -833,6 +833,37 @@ static int rdtgroup_mbm_assign_enable_show(struct kernfs_open_file *of,
 	return 0;
 }
 
+static ssize_t rdtgroup_mbm_assign_enable_write(struct kernfs_open_file *of,
+						char *buf, size_t nbytes,
+						loff_t off)
+{
+	struct rdt_resource *r = of->kn->parent->priv;
+	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
+	struct rdtgroup *rdtgrp;
+	unsigned int enable;
+	int ret;
+
+	if (!r->mbm_assign_capable)
+		return -EINVAL;
+
+	ret = kstrtouint(buf, 0, &enable);
+	if (ret)
+		return ret;
+
+	rdtgrp = rdtgroup_kn_lock_live(of->kn);
+	if (!rdtgrp) {
+		rdtgroup_kn_unlock(of->kn);
+		return -EINVAL;
+	}
+
+	if(hw_res->abmc_enabled != enable)
+		ret = resctrl_arch_set_abmc_enabled(r->rid, enable);
+
+	rdtgroup_kn_unlock(of->kn);
+
+	return ret ?: nbytes;
+}
+
 #ifdef CONFIG_PROC_CPU_RESCTRL
 
 /*
@@ -1891,9 +1922,10 @@ static struct rftype res_common_files[] = {
 	},
 	{
 		.name		= "mbm_assign_enable",
-		.mode		= 0444,
+		.mode		= 0644,
 		.kf_ops		= &rdtgroup_kf_single_ops,
 		.seq_show	= rdtgroup_mbm_assign_enable_show,
+		.write		= rdtgroup_mbm_assign_enable_write,
 	},
 	{
 		.name		= "cpus",
-- 
2.34.1