linux-kernel - [PATCH v8 13/13] x86/itmt: Add debugfs file to show core priorities

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Message-ID: <20250218190822.1039982-14-superm1@kernel.org>
Date: Tue, 18 Feb 2025 13:08:22 -0600
From: Mario Limonciello <superm1@...nel.org>
To: Hans de Goede <hdegoede@...hat.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Mario Limonciello <mario.limonciello@....com>,
	Perry Yuan <perry.yuan@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	"H . Peter Anvin" <hpa@...or.com>,
	Jonathan Corbet <corbet@....net>,
	Huang Rui <ray.huang@....com>,
	"Gautham R . Shenoy" <gautham.shenoy@....com>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	platform-driver-x86@...r.kernel.org (open list:AMD HETERO CORE HARDWARE FEEDBACK DRIVER),
	linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	linux-doc@...r.kernel.org (open list:DOCUMENTATION),
	linux-pm@...r.kernel.org (open list:AMD PSTATE DRIVER)
Subject: [PATCH v8 13/13] x86/itmt: Add debugfs file to show core priorities

From: Mario Limonciello <mario.limonciello@....com>

Multiple drivers can report priorities to ITMT. To aid in debugging
any issues with the values reported by drivers introduce a debugfs
file to read out the values.

Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
v8:
 * New patch

 arch/x86/kernel/itmt.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/arch/x86/kernel/itmt.c b/arch/x86/kernel/itmt.c
index 9cea1fc36c18f..243a769fdd97b 100644
--- a/arch/x86/kernel/itmt.c
+++ b/arch/x86/kernel/itmt.c
@@ -59,6 +59,18 @@ static ssize_t sched_itmt_enabled_write(struct file *filp,
 	return result;
 }
 
+static int sched_core_priority_show(struct seq_file *s, void *unused)
+{
+	int cpu;
+
+	seq_puts(s, "CPU #\tPriority\n");
+	for_each_possible_cpu(cpu)
+		seq_printf(s, "%d\t%d\n", cpu, arch_asym_cpu_priority(cpu));
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(sched_core_priority);
+
 static const struct file_operations dfs_sched_itmt_fops = {
 	.read =         debugfs_read_file_bool,
 	.write =        sched_itmt_enabled_write,
@@ -67,6 +79,7 @@ static const struct file_operations dfs_sched_itmt_fops = {
 };
 
 static struct dentry *dfs_sched_itmt;
+static struct dentry *dfs_sched_core_prio;
 
 /**
  * sched_set_itmt_support() - Indicate platform supports ITMT
@@ -102,6 +115,14 @@ int sched_set_itmt_support(void)
 		return -ENOMEM;
 	}
 
+	dfs_sched_core_prio = debugfs_create_file("sched_core_priority", 0644,
+						  arch_debugfs_dir, NULL,
+						  &sched_core_priority_fops);
+	if (IS_ERR_OR_NULL(dfs_sched_core_prio)) {
+		dfs_sched_core_prio = NULL;
+		return -ENOMEM;
+	}
+
 	sched_itmt_capable = true;
 
 	sysctl_sched_itmt_enabled = 1;
@@ -133,6 +154,8 @@ void sched_clear_itmt_support(void)
 
 	debugfs_remove(dfs_sched_itmt);
 	dfs_sched_itmt = NULL;
+	debugfs_remove(dfs_sched_core_prio);
+	dfs_sched_core_prio = NULL;
 
 	if (sysctl_sched_itmt_enabled) {
 		/* disable sched_itmt if we are no longer ITMT capable */
-- 
2.43.0