perf/x86/intel/cqm: Convert Intel CQM to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153334.096956222@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 20 insertions, 31 deletions

diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index 7b5fd811ef45..783c49ddef29 100644
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -1577,7 +1577,7 @@ static inline void cqm_pick_event_reader(int cpu)
                 cpumask_set_cpu(cpu, &cqm_cpumask);
 }
 
-static void intel_cqm_cpu_starting(unsigned int cpu)
+static int intel_cqm_cpu_starting(unsigned int cpu)
 {
         struct intel_pqr_state *state = &per_cpu(pqr_state, cpu);
         struct cpuinfo_x86 *c = &cpu_data(cpu);
@@ -1588,39 +1588,26 @@ static void intel_cqm_cpu_starting(unsigned int cpu)
 
         WARN_ON(c->x86_cache_max_rmid != cqm_max_rmid);
         WARN_ON(c->x86_cache_occ_scale != cqm_l3_scale);
+
+        cqm_pick_event_reader(cpu);
+        return 0;
 }
 
-static void intel_cqm_cpu_exit(unsigned int cpu)
+static int intel_cqm_cpu_exit(unsigned int cpu)
 {
         int target;
 
         /* Is @cpu the current cqm reader for this package ? */
         if (!cpumask_test_and_clear_cpu(cpu, &cqm_cpumask))
-                return;
+                return 0;
 
         /* Find another online reader in this package */
         target = cpumask_any_but(topology_core_cpumask(cpu), cpu);
 
         if (target < nr_cpu_ids)
                 cpumask_set_cpu(target, &cqm_cpumask);
-}
-
-static int intel_cqm_cpu_notifier(struct notifier_block *nb,
-                                  unsigned long action, void *hcpu)
-{
-        unsigned int cpu  = (unsigned long)hcpu;
-
-        switch (action & ~CPU_TASKS_FROZEN) {
-        case CPU_DOWN_PREPARE:
-                intel_cqm_cpu_exit(cpu);
-                break;
-        case CPU_STARTING:
-                intel_cqm_cpu_starting(cpu);
-                cqm_pick_event_reader(cpu);
-                break;
-        }
 
-        return NOTIFY_OK;
+        return 0;
 }
 
 static const struct x86_cpu_id intel_cqm_match[] = {
@@ -1682,7 +1669,7 @@ out:
 static int __init intel_cqm_init(void)
 {
         char *str = NULL, scale[20];
-        int i, cpu, ret;
+        int cpu, ret;
 
         if (x86_match_cpu(intel_cqm_match))
                 cqm_enabled = true;
@@ -1705,8 +1692,7 @@ static int __init intel_cqm_init(void)
          *
          * Also, check that the scales match on all cpus.
          */
-        cpu_notifier_register_begin();
-
+        get_online_cpus();
         for_each_online_cpu(cpu) {
                 struct cpuinfo_x86 *c = &cpu_data(cpu);
 
@@ -1743,11 +1729,6 @@ static int __init intel_cqm_init(void)
         if (ret)
                 goto out;
 
-        for_each_online_cpu(i) {
-                intel_cqm_cpu_starting(i);
-                cqm_pick_event_reader(i);
-        }
-
         if (mbm_enabled)
                 ret = intel_mbm_init();
         if (ret && !cqm_enabled)
@@ -1772,12 +1753,18 @@ static int __init intel_cqm_init(void)
                 pr_info("Intel MBM enabled\n");
 
         /*
-         * Register the hot cpu notifier once we are sure cqm
+         * Setup the hot cpu notifier once we are sure cqm
          * is enabled to avoid notifier leak.
          */
-        __perf_cpu_notifier(intel_cqm_cpu_notifier);
+        cpuhp_setup_state(CPUHP_AP_PERF_X86_CQM_STARTING,
+                          "AP_PERF_X86_CQM_STARTING",
+                          intel_cqm_cpu_starting, NULL);
+        cpuhp_setup_state(CPUHP_AP_PERF_X86_CQM_ONLINE, "AP_PERF_X86_CQM_ONLINE",
+                          NULL, intel_cqm_cpu_exit);
+
 out:
-        cpu_notifier_register_done();
+        put_online_cpus();
+
         if (ret) {
                 kfree(str);
                 cqm_cleanup();
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 06d77fd0fda3..f9399eeba263 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -25,6 +25,7 @@ enum cpuhp_state {
         CPUHP_AP_PERF_X86_AMD_UNCORE_STARTING,
         CPUHP_AP_PERF_X86_STARTING,
         CPUHP_AP_PERF_X86_AMD_IBS_STARTING,
+        CPUHP_AP_PERF_X86_CQM_STARTING,
         CPUHP_AP_NOTIFY_STARTING,
         CPUHP_AP_ONLINE,
         CPUHP_TEARDOWN_CPU,
@@ -36,6 +37,7 @@ enum cpuhp_state {
         CPUHP_AP_PERF_X86_UNCORE_ONLINE,
         CPUHP_AP_PERF_X86_AMD_UNCORE_ONLINE,
         CPUHP_AP_PERF_X86_RAPL_ONLINE,
+        CPUHP_AP_PERF_X86_CQM_ONLINE,
         CPUHP_AP_NOTIFY_ONLINE,
         CPUHP_AP_ONLINE_DYN,
         CPUHP_AP_ONLINE_DYN_END         = CPUHP_AP_ONLINE_DYN + 30,