FAILED: patch "[PATCH] cpufreq: amd-pstate: Add ->fast_switch() callback" failed to apply to 6.1-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 4badf2eb1e986bdbf34dd2f5d4c979553a86fe54
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023052858-overgrown-profile-8066@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

4badf2eb1e98 ("cpufreq: amd-pstate: Add ->fast_switch() callback")
2dd6d0ebf740 ("cpufreq: amd-pstate: Add guided autonomous mode")
3e6e07805764 ("Documentation: cpufreq: amd-pstate: Move amd_pstate param to alphabetical order")
5014603e409b ("Documentation: introduce amd pstate active mode kernel command line options")
ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
36c5014e5460 ("cpufreq: amd-pstate: optimize driver working mode selection in amd_pstate_param()")
4f3085f87b51 ("cpufreq: amd-pstate: fix kernel hang issue while amd-pstate unregistering")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4badf2eb1e986bdbf34dd2f5d4c979553a86fe54 Mon Sep 17 00:00:00 2001
From: "Gautham R. Shenoy" <gautham.shenoy@amd.com>
Date: Wed, 17 May 2023 16:28:15 +0000
Subject: [PATCH] cpufreq: amd-pstate: Add ->fast_switch() callback

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@amd.com>
Signed-off-by: Wyes Karny <wyes.karny@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 5a3d4aa0f45a..45711fc0a856 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -444,9 +444,8 @@ static int amd_pstate_verify(struct cpufreq_policy_data *policy)
 	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;
@@ -465,14 +464,37 @@ static int amd_pstate_target(struct cpufreq_policy *policy,
 	des_perf = DIV_ROUND_CLOSEST(target_freq * cap_perf,
 				     cpudata->max_freq);
 
-	cpufreq_freq_transition_begin(policy, &freqs);
+	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, false, policy->governor->flags);
-	cpufreq_freq_transition_end(policy, &freqs, false);
+			max_perf, fast_switch, policy->governor->flags);
+
+	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,
@@ -715,6 +737,7 @@ static int amd_pstate_cpu_exit(struct cpufreq_policy *policy)
 
 	freq_qos_remove_request(&cpudata->req[1]);
 	freq_qos_remove_request(&cpudata->req[0]);
+	policy->fast_switch_possible = false;
 	kfree(cpudata);
 
 	return 0;
@@ -1309,6 +1332,7 @@ static struct cpufreq_driver amd_pstate_driver = {
 	.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,