Message-Id: <1498676291-24002-1-git-send-email-anju@linux.vnet.ibm.com>
Date:   Thu, 29 Jun 2017 00:28:09 +0530
From:   Anju T Sudhakar <anju@...ux.vnet.ibm.com>
To:     mpe@...erman.id.au
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        ego@...ux.vnet.ibm.com, bsingharora@...il.com, anton@...ba.org,
        sukadev@...ux.vnet.ibm.com, mikey@...ling.org,
        stewart@...ux.vnet.ibm.com, dja@...ens.net, eranian@...gle.com,
        hemant@...ux.vnet.ibm.com, maddy@...ux.vnet.ibm.com,
        anju@...ux.vnet.ibm.com, tglx@...utronix.de
Subject: [PATCH v11 05/10] powerpc/perf: IMC pmu cpumask and cpuhotplug support

Adds cpumask attribute to be used by each IMC pmu. Only one cpu (any            
online CPU) from each chip for nest PMUs is designated to read counters.        
                                                                                
On CPU hotplug, dying CPU is checked to see whether it is one of the            
designated cpus, if yes, next online cpu from the same chip (for nest           
units) is designated as new cpu to read counters. For this purpose, we          
introduce a new state : CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE.                  
                                                                                
Signed-off-by: Anju T Sudhakar <anju@...ux.vnet.ibm.com>                        
Signed-off-by: Hemant Kumar <hemant@...ux.vnet.ibm.com>                         
Signed-off-by: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com> 
---
 arch/powerpc/include/asm/imc-pmu.h             |   1 +
 arch/powerpc/include/asm/opal-api.h            |  10 +-
 arch/powerpc/include/asm/opal.h                |   4 +
 arch/powerpc/perf/imc-pmu.c                    | 188 ++++++++++++++++++++++++-
 arch/powerpc/platforms/powernv/opal-imc.c      |  18 ++-
 arch/powerpc/platforms/powernv/opal-wrappers.S |   3 +
 include/linux/cpuhotplug.h                     |   1 +
 7 files changed, 219 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/imc-pmu.h b/arch/powerpc/include/asm/imc-pmu.h
index 25d0c57..650c1e8 100644
--- a/arch/powerpc/include/asm/imc-pmu.h
+++ b/arch/powerpc/include/asm/imc-pmu.h
@@ -24,6 +24,7 @@
  * For static allocation of some of the structures.
  */
 #define IMC_MAX_PMUS			32
+#define IMC_MAX_CHIPS			32
 
 /*
  * This macro is used for memory buffer allocation of
diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
index cb3e624..fdacb03 100644
--- a/arch/powerpc/include/asm/opal-api.h
+++ b/arch/powerpc/include/asm/opal-api.h
@@ -190,7 +190,10 @@
 #define OPAL_NPU_INIT_CONTEXT			146
 #define OPAL_NPU_DESTROY_CONTEXT		147
 #define OPAL_NPU_MAP_LPAR			148
-#define OPAL_LAST				148
+#define OPAL_IMC_COUNTERS_INIT			149
+#define OPAL_IMC_COUNTERS_START			150
+#define OPAL_IMC_COUNTERS_STOP			151
+#define OPAL_LAST				151
 
 /* Device tree flags */
 
@@ -1003,6 +1006,11 @@ enum {
 	XIVE_DUMP_EMU_STATE	= 5,
 };
 
+/* Argument to OPAL_IMC_COUNTERS_*  */
+enum {
+	OPAL_IMC_COUNTERS_NEST = 1,
+};
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __OPAL_API_H */
diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 588fb1c..48842d2 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -268,6 +268,10 @@ int64_t opal_xive_free_irq(uint32_t girq);
 int64_t opal_xive_sync(uint32_t type, uint32_t id);
 int64_t opal_xive_dump(uint32_t type, uint32_t id);
 
+int64_t opal_imc_counters_init(uint32_t type, uint64_t address, uint64_t cpu);
+int64_t opal_imc_counters_start(uint32_t type, uint64_t cpu_pir);
+int64_t opal_imc_counters_stop(uint32_t type, uint64_t cpu_pir);
+
 /* Internal functions */
 extern int early_init_dt_scan_opal(unsigned long node, const char *uname,
 				   int depth, void *data);
diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index 326c9ea..b0bcb77 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -20,6 +20,16 @@
 
 /* Needed for sanity check */
 struct imc_pmu *per_nest_pmu_arr[IMC_MAX_PMUS];
+static cpumask_t nest_imc_cpumask;
+static int nest_imc_cpumask_initialized;
+
+static atomic_t nest_pmus;
+static atomic_t nest_events[IMC_MAX_CHIPS];
+/* Used to avoid races in counting the nest-pmu units inited */
+static DEFINE_MUTEX(imc_nest_inited_reserve);
+/* Used to avoid races in calling enable/disable nest-pmu units */
+static DEFINE_MUTEX(imc_nest_reserve);
+
 
 struct imc_pmu *imc_event_to_pmu(struct perf_event *event)
 {
@@ -43,9 +53,135 @@ static struct attribute_group imc_format_group = {
 	.attrs = nest_imc_format_attrs,
 };
 
+/* Get the cpumask printed to a buffer "buf" */
+static ssize_t imc_pmu_cpumask_get_attr(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	cpumask_t *active_mask;
+
+	active_mask = &nest_imc_cpumask;
+	return cpumap_print_to_pagebuf(true, buf, active_mask);
+}
+
+static DEVICE_ATTR(cpumask, S_IRUGO, imc_pmu_cpumask_get_attr, NULL);
+
+static struct attribute *imc_pmu_cpumask_attrs[] = {
+	&dev_attr_cpumask.attr,
+	NULL,
+};
+
+static struct attribute_group imc_pmu_cpumask_attr_group = {
+	.attrs = imc_pmu_cpumask_attrs,
+};
+
+static void nest_change_cpu_context(int old_cpu, int new_cpu)
+{
+	struct imc_pmu **pn = per_nest_pmu_arr;
+	int i;
+
+	if (old_cpu < 0 || new_cpu < 0)
+		return;
+
+	for (i = 0; *pn && i < IMC_MAX_PMUS; i++, pn++)
+		perf_pmu_migrate_context(&(*pn)->pmu, old_cpu, new_cpu);
+}
+
+static int ppc_nest_imc_cpu_offline(unsigned int cpu)
+{
+	int nid, target = -1;
+	const struct cpumask *l_cpumask;
+
+	/*
+	 * Check in the designated list for this cpu. Dont bother
+	 * if not one of them.
+	 */
+	if (!cpumask_test_and_clear_cpu(cpu, &nest_imc_cpumask))
+		return 0;
+
+	/*
+	 * Now that this cpu is one of the designated,
+	 * find a next cpu a) which is online and b) in same chip.
+	 */
+	nid = cpu_to_node(cpu);
+	l_cpumask = cpumask_of_node(nid);
+	target = cpumask_any_but(l_cpumask, cpu);
+
+	/*
+	* Update the cpumask with the target cpu and
+	* migrate the context if needed
+	*/
+	if (target >= 0 && target < nr_cpu_ids) {
+		cpumask_set_cpu(target, &nest_imc_cpumask);
+		nest_change_cpu_context(cpu, target);
+	} else {
+		opal_imc_counters_stop(OPAL_IMC_COUNTERS_NEST,
+				       get_hard_smp_processor_id(cpu));
+	}
+	return 0;
+}
+
+static int ppc_nest_imc_cpu_online(unsigned int cpu)
+{
+	const struct cpumask *l_cpumask;
+	static struct cpumask tmp_mask;
+	int res;
+
+	/* Get the cpumask of this node */
+	l_cpumask = cpumask_of_node(cpu_to_node(cpu));
+
+	/*
+	 * If this is not the first online CPU on this node, then
+	 * just return.
+	 */
+	if (cpumask_and(&tmp_mask, l_cpumask, &nest_imc_cpumask))
+		return 0;
+
+	/*
+	 * If this is the first online cpu on this node
+	 * disable the nest counters by making an OPAL call.
+	 */
+	res = opal_imc_counters_stop(OPAL_IMC_COUNTERS_NEST,
+				     get_hard_smp_processor_id(cpu));
+	if (res)
+		return res;
+
+	/* Make this CPU the designated target for counter collection */
+	cpumask_set_cpu(cpu, &nest_imc_cpumask);
+	return 0;
+}
+
+static int nest_pmu_cpumask_init(void)
+{
+	return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE,
+				 "perf/powerpc/imc:online",
+				 ppc_nest_imc_cpu_online,
+				 ppc_nest_imc_cpu_offline);
+}
+
+static void nest_imc_counters_release(struct perf_event *event)
+{
+	int rc, node_id;
+	/*
+	 * See if we need to disable the nest PMU.
+	 * If no events are currently in use, then we have to take a
+	 * mutex to ensure that we don't race with another task doing
+	 * enable or disable the nest counters.
+	 */
+	node_id = cpu_to_node(event->cpu);
+	if (atomic_dec_return(&nest_events[node_id]) == 0) {
+		mutex_lock(&imc_nest_reserve);
+		rc = opal_imc_counters_stop(OPAL_IMC_COUNTERS_NEST,
+					    get_hard_smp_processor_id(event->cpu));
+		mutex_unlock(&imc_nest_reserve);
+		if (rc)
+			pr_err("IMC: Disable counters failed for node %d\n", node_id);
+	}
+}
+
 static int nest_imc_event_init(struct perf_event *event)
 {
-	int chip_id;
+	int chip_id, rc, node_id;
 	u32 l_config, config = event->attr.config;
 	struct imc_mem_info *pcni;
 	struct imc_pmu *pmu;
@@ -98,6 +234,25 @@ static int nest_imc_event_init(struct perf_event *event)
 	 */
 	l_config = config & IMC_EVENT_OFFSET_MASK;
 	event->hw.event_base = (u64)pcni->vbase[l_config/PAGE_SIZE] + (config & ~PAGE_MASK);
+	/*
+	* Nest pmu units are enabled only when it is used.
+	* See if this is triggered for the first time.
+	* If yes, take the mutex lock and enable the nest counters.
+	* If not, just increment the count in nest_events.
+	*/
+	node_id = cpu_to_node(event->cpu);
+	if (atomic_inc_return(&nest_events[node_id]) == 1) {
+		mutex_lock(&imc_nest_reserve);
+		rc = opal_imc_counters_start(OPAL_IMC_COUNTERS_NEST,
+					     get_hard_smp_processor_id(event->cpu));
+		mutex_unlock(&imc_nest_reserve);
+		if (rc) {
+			atomic_dec_return(&nest_events[node_id]);
+			pr_err("IMC: Unable to start the counters for node %d\n", node_id);
+			return -ENODEV;
+		}
+	}
+	event->destroy = nest_imc_counters_release;
 	return 0;
 }
 
@@ -175,6 +330,7 @@ static int update_pmu_ops(struct imc_pmu *pmu)
 	pmu->pmu.start = imc_event_start;
 	pmu->pmu.stop = imc_event_stop;
 	pmu->pmu.read = imc_perf_event_update;
+	pmu->attr_groups[IMC_CPUMASK_ATTR] = &imc_pmu_cpumask_attr_group;
 	pmu->attr_groups[IMC_FORMAT_ATTR] = &imc_format_group;
 	pmu->pmu.attr_groups = pmu->attr_groups;
 
@@ -244,12 +400,31 @@ static int update_events_in_group(struct imc_events *events,
  * @events:	events memory for this pmu.
  * @idx:	number of event entries created.
  * @pmu_ptr:	memory allocated for this pmu.
+ *
+ * init_imc_pmu() setup the cpu mask information for these pmus and setup
+ * the state machine hotplug notifiers as well.
  */
 int init_imc_pmu(struct imc_events *events, int idx,
 		 struct imc_pmu *pmu_ptr)
 {
 	int ret = -ENODEV;
-
+	/* Add cpumask and register for hotplug notification */
+	if (atomic_inc_return(&nest_pmus) == 1) {
+		/*
+		 * Nest imc pmu need only one cpu per chip, we initialize the
+		 * cpumask for the first nest imc pmu and use the same for the rest.
+		 * To handle the cpuhotplug callback unregister, we track
+		 * the number of nest pmus registers in "nest_pmus".
+		 * "nest_imc_cpumask_initialized" is set to zero during cpuhotplug
+		 * callback unregister.
+		 */
+		ret = nest_pmu_cpumask_init();
+		if (ret)
+			goto err_free;
+		mutex_lock(&imc_nest_inited_reserve);
+		nest_imc_cpumask_initialized = 1;
+		mutex_unlock(&imc_nest_inited_reserve);
+	}
 	ret = update_events_in_group(events, idx, pmu_ptr);
 	if (ret)
 		goto err_free;
@@ -274,6 +449,13 @@ int init_imc_pmu(struct imc_events *events, int idx,
 			kfree(pmu_ptr->attr_groups[IMC_EVENT_ATTR]->attrs);
 		kfree(pmu_ptr->attr_groups[IMC_EVENT_ATTR]);
 	}
-
+	if (pmu_ptr->domain == IMC_DOMAIN_NEST) {
+		if (atomic_dec_return(&nest_pmus) == 0) {
+			mutex_lock(&imc_nest_inited_reserve);
+			cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE);
+			nest_imc_cpumask_initialized = 0;
+			mutex_unlock(&imc_nest_inited_reserve);
+		}
+	}
 	return ret;
 }
diff --git a/arch/powerpc/platforms/powernv/opal-imc.c b/arch/powerpc/platforms/powernv/opal-imc.c
index a68d66d..a970ed3 100644
--- a/arch/powerpc/platforms/powernv/opal-imc.c
+++ b/arch/powerpc/platforms/powernv/opal-imc.c
@@ -467,6 +467,19 @@ static int imc_pmu_create(struct device_node *parent, int pmu_index, int domain)
 	return ret;
 }
 
+static void disable_nest_counters(void)
+{
+	int nid, cpu;
+	struct cpumask *l_cpumask;
+
+	for_each_online_node(nid) {
+		l_cpumask = cpumask_of_node(nid);
+		cpu = cpumask_first(l_cpumask);
+		opal_imc_counters_stop(OPAL_IMC_COUNTERS_NEST,
+				       get_hard_smp_processor_id(cpu));
+	}
+}
+
 static int opal_imc_counters_probe(struct platform_device *pdev)
 {
 	struct device_node *imc_dev = NULL;
@@ -479,9 +492,10 @@ static int opal_imc_counters_probe(struct platform_device *pdev)
 	/*
 	 * Check whether this is kdump kernel. If yes, just return.
 	 */
-	if (is_kdump_kernel())
+	if (is_kdump_kernel()) {
+		disable_nest_counters();
 		return -ENODEV;
-
+	}
 	imc_dev = pdev->dev.of_node;
 	if (!imc_dev)
 		return -ENODEV;
diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
index f620572..1828b24f 100644
--- a/arch/powerpc/platforms/powernv/opal-wrappers.S
+++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
@@ -310,3 +310,6 @@ OPAL_CALL(opal_xive_dump,			OPAL_XIVE_DUMP);
 OPAL_CALL(opal_npu_init_context,		OPAL_NPU_INIT_CONTEXT);
 OPAL_CALL(opal_npu_destroy_context,		OPAL_NPU_DESTROY_CONTEXT);
 OPAL_CALL(opal_npu_map_lpar,			OPAL_NPU_MAP_LPAR);
+OPAL_CALL(opal_imc_counters_init,              OPAL_IMC_COUNTERS_INIT);
+OPAL_CALL(opal_imc_counters_start,             OPAL_IMC_COUNTERS_START);
+OPAL_CALL(opal_imc_counters_stop,              OPAL_IMC_COUNTERS_STOP);
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 0f2a803..dca7f2b 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -139,6 +139,7 @@ enum cpuhp_state {
 	CPUHP_AP_PERF_ARM_L2X0_ONLINE,
 	CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
 	CPUHP_AP_PERF_ARM_QCOM_L3_ONLINE,
+	CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE,
 	CPUHP_AP_WORKQUEUE_ONLINE,
 	CPUHP_AP_RCUTREE_ONLINE,
 	CPUHP_AP_ONLINE_DYN,
-- 
2.7.4

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