forked from Minki/linux
intel_pstate: Update frequencies of policy->cpus only from ->set_policy()
The intel-pstate driver is using intel_pstate_hwp_set() from two separate paths, i.e. ->set_policy() callback and sysfs update path for the files present in /sys/devices/system/cpu/intel_pstate/ directory. While an update to the sysfs path applies to all the CPUs being managed by the driver (which essentially means all the online CPUs), the update via the ->set_policy() callback applies to a smaller group of CPUs managed by the policy for which ->set_policy() is called. And so, intel_pstate_hwp_set() should update frequencies of only the CPUs that are part of policy->cpus mask, while it is called from ->set_policy() callback. In order to do that, add a parameter (cpumask) to intel_pstate_hwp_set() and apply the frequency changes only to the concerned CPUs. For ->set_policy() path, we are only concerned about policy->cpus, and so policy->rwsem lock taken by the core prior to calling ->set_policy() is enough to take care of any races. The larger lock acquired by get_online_cpus() is required only for the updates to sysfs files. Add another routine, intel_pstate_hwp_set_online_cpus(), and call it from the sysfs update paths. This also fixes a lockdep reported recently, where policy->rwsem and get_online_cpus() could have been acquired in any order causing an ABBA deadlock. The sequence of events leading to that was: intel_pstate_init(...) ...cpufreq_online(...) down_write(&policy->rwsem); // Locks policy->rwsem ... cpufreq_init_policy(policy); ...intel_pstate_hwp_set(); get_online_cpus(); // Temporarily locks cpu_hotplug.lock ... up_write(&policy->rwsem); pm_suspend(...) ...disable_nonboot_cpus() _cpu_down() cpu_hotplug_begin(); // Locks cpu_hotplug.lock __cpu_notify(CPU_DOWN_PREPARE, ...); ...cpufreq_offline_prepare(); down_write(&policy->rwsem); // Locks policy->rwsem Reported-and-tested-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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@ -286,7 +286,7 @@ static inline void update_turbo_state(void)
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cpu->pstate.max_pstate == cpu->pstate.turbo_pstate);
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}
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static void intel_pstate_hwp_set(void)
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static void intel_pstate_hwp_set(const struct cpumask *cpumask)
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{
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int min, hw_min, max, hw_max, cpu, range, adj_range;
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u64 value, cap;
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@ -296,9 +296,7 @@ static void intel_pstate_hwp_set(void)
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hw_max = HWP_HIGHEST_PERF(cap);
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range = hw_max - hw_min;
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get_online_cpus();
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for_each_online_cpu(cpu) {
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for_each_cpu(cpu, cpumask) {
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rdmsrl_on_cpu(cpu, MSR_HWP_REQUEST, &value);
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adj_range = limits->min_perf_pct * range / 100;
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min = hw_min + adj_range;
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@ -317,7 +315,12 @@ static void intel_pstate_hwp_set(void)
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value |= HWP_MAX_PERF(max);
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wrmsrl_on_cpu(cpu, MSR_HWP_REQUEST, value);
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}
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}
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static void intel_pstate_hwp_set_online_cpus(void)
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{
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get_online_cpus();
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intel_pstate_hwp_set(cpu_online_mask);
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put_online_cpus();
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}
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@ -439,7 +442,7 @@ static ssize_t store_no_turbo(struct kobject *a, struct attribute *b,
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limits->no_turbo = clamp_t(int, input, 0, 1);
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if (hwp_active)
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intel_pstate_hwp_set();
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intel_pstate_hwp_set_online_cpus();
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return count;
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}
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@ -465,7 +468,7 @@ static ssize_t store_max_perf_pct(struct kobject *a, struct attribute *b,
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int_tofp(100));
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if (hwp_active)
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intel_pstate_hwp_set();
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intel_pstate_hwp_set_online_cpus();
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return count;
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}
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@ -490,7 +493,7 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,
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int_tofp(100));
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if (hwp_active)
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intel_pstate_hwp_set();
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intel_pstate_hwp_set_online_cpus();
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return count;
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}
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@ -1141,7 +1144,7 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
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pr_debug("intel_pstate: set performance\n");
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limits = &performance_limits;
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if (hwp_active)
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intel_pstate_hwp_set();
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intel_pstate_hwp_set(policy->cpus);
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return 0;
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}
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@ -1173,7 +1176,7 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
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int_tofp(100));
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if (hwp_active)
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intel_pstate_hwp_set();
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intel_pstate_hwp_set(policy->cpus);
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return 0;
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}
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