intel_pstate: Set core to min P state during core offline

Change to use the new ->stop_cpu() callback to do clean up during CPU
hotplug. The requested P state for an offline core will be used by the
hardware coordination function to select the package P state. If the
core is under load when it is offlined it will fix the package P state
floor to the requested P state of offline core.

Reported-by: Patrick Marlier <patrick.marlier@gmail.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -446,7 +446,7 @@ static void core_set_pstate(struct cpudata *cpudata, int pstate)
 	if (limits.no_turbo)
 		val |= (u64)1 << 32;
 
-	wrmsrl(MSR_IA32_PERF_CTL, val);
+	wrmsrl_on_cpu(cpudata->cpu, MSR_IA32_PERF_CTL, val);
 }
 
 static struct cpu_defaults core_params = {
@@ -771,14 +771,17 @@ static int intel_pstate_verify_policy(struct cpufreq_policy *policy)
 	return 0;
 }
 
-static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
+static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
 {
-	int cpu = policy->cpu;
+	int cpu_num = policy->cpu;
+	struct cpudata *cpu = all_cpu_data[cpu_num];
 
-	del_timer(&all_cpu_data[cpu]->timer);
-	kfree(all_cpu_data[cpu]);
-	all_cpu_data[cpu] = NULL;
-	return 0;
+	pr_info("intel_pstate CPU %d exiting\n", cpu_num);
+
+	del_timer(&all_cpu_data[cpu_num]->timer);
+	intel_pstate_set_pstate(cpu, cpu->pstate.min_pstate);
+	kfree(all_cpu_data[cpu_num]);
+	all_cpu_data[cpu_num] = NULL;
 }
 
 static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
@@ -816,7 +819,7 @@ static struct cpufreq_driver intel_pstate_driver = {
 	.setpolicy	= intel_pstate_set_policy,
 	.get		= intel_pstate_get,
 	.init		= intel_pstate_cpu_init,
-	.exit		= intel_pstate_cpu_exit,
+	.stop_cpu	= intel_pstate_stop_cpu,
 	.name		= "intel_pstate",
 };