Commit 4badf2eb authored by Gautham R. Shenoy's avatar Gautham R. Shenoy Committed by Rafael J. Wysocki
Browse files

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: 1d215f03 ("cpufreq: amd-pstate: Add fast switch function for AMD P-State")
Signed-off-by: default avatarGautham R. Shenoy <gautham.shenoy@amd.com>
Signed-off-by: default avatarWyes Karny <wyes.karny@amd.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 44c026a7

drivers/cpufreq/amd-pstate.c

+30 −6
Original line number Diff line number Diff line
@@ -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);



	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);

			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,