linux-kernel - [PATCH 1/2] cpufreq: intel_pstate: hybrid: Avoid exposing two global attributes

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Date:   Wed, 12 May 2021 16:15:48 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PM <linux-pm@...r.kernel.org>
Cc:     Linux ACPI <linux-acpi@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Len Brown <len.brown@...el.com>, Chen Yu <yu.c.chen@...el.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Zhang Rui <rui.zhang@...el.com>
Subject: [PATCH 1/2] cpufreq: intel_pstate: hybrid: Avoid exposing two global attributes

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

The turbo_pct and num_pstates sysfs attributes represent CPU
properties that may be different for differenty types of CPUs in
a hybrid processor, so avoid exposing them in that case.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 Documentation/admin-guide/pm/intel_pstate.rst |    6 ++++++
 drivers/cpufreq/intel_pstate.c                |   15 +++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

Index: linux-pm/Documentation/admin-guide/pm/intel_pstate.rst
===================================================================
--- linux-pm.orig/Documentation/admin-guide/pm/intel_pstate.rst
+++ linux-pm/Documentation/admin-guide/pm/intel_pstate.rst
@@ -365,6 +365,9 @@ argument is passed to the kernel in the
 	inclusive) including both turbo and non-turbo P-states (see
 	`Turbo P-states Support`_).
 
+	This attribute is present only if the value exposed by it is the same
+	for all of the CPUs in the system.
+
 	The value of this attribute is not affected by the ``no_turbo``
 	setting described `below <no_turbo_attr_>`_.
 
@@ -374,6 +377,9 @@ argument is passed to the kernel in the
 	Ratio of the `turbo range <turbo_>`_ size to the size of the entire
 	range of supported P-states, in percent.
 
+	This attribute is present only if the value exposed by it is the same
+	for all of the CPUs in the system.
+
 	This attribute is read-only.
 
 .. _no_turbo_attr:
Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -1365,8 +1365,6 @@ define_one_global_rw(energy_efficiency);
 static struct attribute *intel_pstate_attributes[] = {
 	&status.attr,
 	&no_turbo.attr,
-	&turbo_pct.attr,
-	&num_pstates.attr,
 	NULL
 };
 
@@ -1391,6 +1389,14 @@ static void __init intel_pstate_sysfs_ex
 	if (WARN_ON(rc))
 		return;
 
+	if (!boot_cpu_has(X86_FEATURE_HYBRID_CPU)) {
+		rc = sysfs_create_file(intel_pstate_kobject, &turbo_pct.attr);
+		WARN_ON(rc);
+
+		rc = sysfs_create_file(intel_pstate_kobject, &num_pstates.attr);
+		WARN_ON(rc);
+	}
+
 	/*
 	 * If per cpu limits are enforced there are no global limits, so
 	 * return without creating max/min_perf_pct attributes
@@ -1417,6 +1423,11 @@ static void __init intel_pstate_sysfs_re
 
 	sysfs_remove_group(intel_pstate_kobject, &intel_pstate_attr_group);
 
+	if (!boot_cpu_has(X86_FEATURE_HYBRID_CPU)) {
+		sysfs_remove_file(intel_pstate_kobject, &num_pstates.attr);
+		sysfs_remove_file(intel_pstate_kobject, &turbo_pct.attr);
+	}
+
 	if (!per_cpu_limits) {
 		sysfs_remove_file(intel_pstate_kobject, &max_perf_pct.attr);
 		sysfs_remove_file(intel_pstate_kobject, &min_perf_pct.attr);