This is a note to let you know that I've just added the patch titled
cpufreq: amd-pstate: Add ->fast_switch() callback
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cpufreq-amd-pstate-add-fast_switch-callback.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4badf2eb1e986bdbf34dd2f5d4c979553a86fe54 Mon Sep 17 00:00:00 2001
From: "Gautham R. Shenoy" <gautham.shenoy@xxxxxxx>
Date: Wed, 17 May 2023 16:28:15 +0000
Subject: cpufreq: amd-pstate: Add ->fast_switch() callback
From: Gautham R. Shenoy <gautham.shenoy@xxxxxxx>
commit 4badf2eb1e986bdbf34dd2f5d4c979553a86fe54 upstream.
Schedutil normally calls the adjust_perf callback for drivers with
adjust_perf callback available and fast_switch_possible flag set.
However, when frequency invariance is disabled and schedutil tries to
invoke fast_switch. So, there is a chance of kernel crash if this
function pointer is not set. To protect against this scenario add
fast_switch callback to amd_pstate driver.
Fixes: 1d215f0319c2 ("cpufreq: amd-pstate: Add fast switch function for AMD P-State")
Signed-off-by: Gautham R. Shenoy <gautham.shenoy@xxxxxxx>
Signed-off-by: Wyes Karny <wyes.karny@xxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/cpufreq/amd-pstate.c | 37 ++++++++++++++++++++++++++++++-------
1 file changed, 30 insertions(+), 7 deletions(-)
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -249,9 +249,8 @@ static int amd_pstate_verify(struct cpuf
return 0;
}
-static int amd_pstate_target(struct cpufreq_policy *policy,
- unsigned int target_freq,
- unsigned int relation)
+static int amd_pstate_update_freq(struct cpufreq_policy *policy,
+ unsigned int target_freq, bool fast_switch)
{
struct cpufreq_freqs freqs;
struct amd_cpudata *cpudata = policy->driver_data;
@@ -270,14 +269,36 @@ static int amd_pstate_target(struct cpuf
des_perf = DIV_ROUND_CLOSEST(target_freq * cap_perf,
cpudata->max_freq);
- cpufreq_freq_transition_begin(policy, &freqs);
- amd_pstate_update(cpudata, min_perf, des_perf,
- max_perf, false);
- cpufreq_freq_transition_end(policy, &freqs, false);
+ WARN_ON(fast_switch && !policy->fast_switch_enabled);
+ /*
+ * If fast_switch is desired, then there aren't any registered
+ * transition notifiers. See comment for
+ * cpufreq_enable_fast_switch().
+ */
+ if (!fast_switch)
+ cpufreq_freq_transition_begin(policy, &freqs);
+
+ amd_pstate_update(cpudata, min_perf, des_perf, max_perf, fast_switch);
+
+ if (!fast_switch)
+ cpufreq_freq_transition_end(policy, &freqs, false);
return 0;
}
+static int amd_pstate_target(struct cpufreq_policy *policy,
+ unsigned int target_freq,
+ unsigned int relation)
+{
+ return amd_pstate_update_freq(policy, target_freq, false);
+}
+
+static unsigned int amd_pstate_fast_switch(struct cpufreq_policy *policy,
+ unsigned int target_freq)
+{
+ return amd_pstate_update_freq(policy, target_freq, true);
+}
+
static void amd_pstate_adjust_perf(unsigned int cpu,
unsigned long _min_perf,
unsigned long target_perf,
@@ -523,6 +544,7 @@ static int amd_pstate_cpu_exit(struct cp
freq_qos_remove_request(&cpudata->req[1]);
freq_qos_remove_request(&cpudata->req[0]);
+ policy->fast_switch_possible = false;
kfree(cpudata);
return 0;
@@ -614,6 +636,7 @@ static struct cpufreq_driver amd_pstate_
.flags = CPUFREQ_CONST_LOOPS | CPUFREQ_NEED_UPDATE_LIMITS,
.verify = amd_pstate_verify,
.target = amd_pstate_target,
+ .fast_switch = amd_pstate_fast_switch,
.init = amd_pstate_cpu_init,
.exit = amd_pstate_cpu_exit,
.suspend = amd_pstate_cpu_suspend,
Patches currently in stable-queue which might be from gautham.shenoy@xxxxxxx are
queue-6.1/cpufreq-amd-pstate-add-fast_switch-callback.patch
