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

From: Mario Limonciello
Date: Tue Feb 18 2025 - 14:13:22 EST


From: Mario Limonciello <mario.limonciello@xxxxxxx>

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@xxxxxxx>
---
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