linux-kernel - [PATCH 5/9] x86/resctrl: Introduce mon_configurable to detect Bandwidth Monitoring Event Configuration

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Message-ID: <165757555546.416408.18035193047484698923.stgit@bmoger-ubuntu>
Date:   Mon, 11 Jul 2022 16:39:15 -0500
From:   Babu Moger <babu.moger@....com>
To:     <fenghua.yu@...el.com>, <reinette.chatre@...el.com>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>
CC:     <dave.hansen@...ux.intel.com>, <x86@...nel.org>, <hpa@...or.com>,
        <corbet@....net>, <hpa@...or.com>, <linux-kernel@...r.kernel.org>,
        <linux-doc@...r.kernel.org>
Subject: [PATCH 5/9] x86/resctrl: Introduce mon_configurable to detect
 Bandwidth Monitoring Event Configuration

Newer AMD processors support the new feature Bandwidth Monitoring Event
Configuration (BMEC). The events mbm_total_bytes and mbm_local_bytes
are configurable when this feature is present.

Set mon_configurable if the feature is available.

Signed-off-by: Babu Moger <babu.moger@....com>
---
 arch/x86/kernel/cpu/resctrl/monitor.c  |   14 ++++++++++++++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c |   17 +++++++++++++++++
 include/linux/resctrl.h                |    1 +
 3 files changed, 32 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index eaf25a234ff5..b9de417dac1c 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -682,6 +682,16 @@ static void l3_mon_evt_init(struct rdt_resource *r)
 		list_add_tail(&mbm_local_event.list, &r->evt_list);
 }
 
+
+void __rdt_get_mon_l3_config_amd(struct rdt_resource *r)
+{
+	/*
+	 * Check if CPU supports the Bandwidth Monitoring Event Configuration
+	 */
+	if (boot_cpu_has(X86_FEATURE_BMEC))
+		r->mon_configurable = true;
+}
+
 int rdt_get_mon_l3_config(struct rdt_resource *r)
 {
 	unsigned int mbm_offset = boot_cpu_data.x86_cache_mbm_width_offset;
@@ -714,6 +724,10 @@ int rdt_get_mon_l3_config(struct rdt_resource *r)
 	if (ret)
 		return ret;
 
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+		__rdt_get_mon_l3_config_amd(r);
+
+
 	l3_mon_evt_init(r);
 
 	r->mon_capable = true;
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index fc5286067201..855483b297a8 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -995,6 +995,16 @@ static int rdt_num_rmids_show(struct kernfs_open_file *of,
 	return 0;
 }
 
+static int rdt_mon_configurable_show(struct kernfs_open_file *of,
+				     struct seq_file *seq, void *v)
+{
+	struct rdt_resource *r = of->kn->parent->priv;
+
+	seq_printf(seq, "%d\n", r->mon_configurable);
+
+	return 0;
+}
+
 static int rdt_mon_features_show(struct kernfs_open_file *of,
 				 struct seq_file *seq, void *v)
 {
@@ -1447,6 +1457,13 @@ static struct rftype res_common_files[] = {
 		.seq_show	= rdt_num_rmids_show,
 		.fflags		= RF_MON_INFO,
 	},
+	{
+		.name		= "mon_configurable",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdt_mon_configurable_show,
+		.fflags		= RF_MON_INFO,
+	},
 	{
 		.name		= "cbm_mask",
 		.mode		= 0444,
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 21deb5212bbd..4ee2b606ac14 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -154,6 +154,7 @@ struct rdt_resource {
 	bool			mon_enabled;
 	bool			alloc_capable;
 	bool			mon_capable;
+	bool			mon_configurable;
 	int			num_rmid;
 	int			cache_level;
 	struct resctrl_cache	cache;