Re: [PATCH 6.3.y] cpufreq: amd-pstate: Add ->fast_switch() callback

On 30 May 11:16, Wyes Karny wrote:

From: "Gautham R. Shenoy" gautham.shenoy@amd.com

[ Upstream commit 3bf8c6307bad5c0cc09cde982e146d847859b651 ]

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 (cherry picked from commit 4badf2eb1e986bdbf34dd2f5d4c979553a86fe54)

---

drivers/cpufreq/amd-pstate.c | 37 +++++++++++++++++++++++++++++------- 1 file changed, 30 insertions(+), 7 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index 8dd46fad151e..7cce90d16b8d 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -422,9 +422,8 @@ 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; @@ -443,14 +442,36 @@ 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);
• 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, @@ -692,6 +713,7 @@ 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; @@ -1226,6 +1248,7 @@ 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,

Please ignore this. Wrong patch. Sorry for inconvenience.

Thanks, Wyes

-- 2.34.1