[RESEND,v5,2/4] drivers/nvdimm: Add perf interface to expose nvdimm performance stats

diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile
index 29203f3d3069..25dba6095612 100644
--- a/drivers/nvdimm/Makefile
+++ b/drivers/nvdimm/Makefile
@@ -18,6 +18,7 @@  nd_e820-y := e820.o
 libnvdimm-y := core.o
 libnvdimm-y += bus.o
 libnvdimm-y += dimm_devs.o
+libnvdimm-y += nd_perf.o
 libnvdimm-y += dimm.o
 libnvdimm-y += region_devs.o
 libnvdimm-y += region.o
diff --git a/drivers/nvdimm/nd_perf.c b/drivers/nvdimm/nd_perf.c
new file mode 100644
index 000000000000..314415894acf
--- /dev/null
+++ b/drivers/nvdimm/nd_perf.c
@@ -0,0 +1,328 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * nd_perf.c: NVDIMM Device Performance Monitoring Unit support
+ *
+ * Perf interface to expose nvdimm performance stats.
+ *
+ * Copyright (C) 2021 IBM Corporation
+ */
+
+#define pr_fmt(fmt) "nvdimm_pmu: " fmt
+
+#include <linux/nd.h>
+
+#define EVENT(_name, _code)     enum{_name = _code}
+
+/*
+ * NVDIMM Events codes.
+ */
+
+/* Controller Reset Count */
+EVENT(CTL_RES_CNT,		0x1);
+/* Controller Reset Elapsed Time */
+EVENT(CTL_RES_TM,		0x2);
+/* Power-on Seconds */
+EVENT(POWERON_SECS,		0x3);
+/* Life Remaining */
+EVENT(MEM_LIFE,		0x4);
+/* Critical Resource Utilization */
+EVENT(CRI_RES_UTIL,		0x5);
+/* Host Load Count */
+EVENT(HOST_L_CNT,		0x6);
+/* Host Store Count */
+EVENT(HOST_S_CNT,		0x7);
+/* Host Store Duration */
+EVENT(HOST_S_DUR,		0x8);
+/* Host Load Duration */
+EVENT(HOST_L_DUR,		0x9);
+/* Media Read Count */
+EVENT(MED_R_CNT,		0xa);
+/* Media Write Count */
+EVENT(MED_W_CNT,		0xb);
+/* Media Read Duration */
+EVENT(MED_R_DUR,		0xc);
+/* Media Write Duration */
+EVENT(MED_W_DUR,		0xd);
+/* Cache Read Hit Count */
+EVENT(CACHE_RH_CNT,		0xe);
+/* Cache Write Hit Count */
+EVENT(CACHE_WH_CNT,		0xf);
+/* Fast Write Count */
+EVENT(FAST_W_CNT,		0x10);
+
+NVDIMM_EVENT_ATTR(ctl_res_cnt,		CTL_RES_CNT);
+NVDIMM_EVENT_ATTR(ctl_res_tm,		CTL_RES_TM);
+NVDIMM_EVENT_ATTR(poweron_secs,		POWERON_SECS);
+NVDIMM_EVENT_ATTR(mem_life,		MEM_LIFE);
+NVDIMM_EVENT_ATTR(cri_res_util,		CRI_RES_UTIL);
+NVDIMM_EVENT_ATTR(host_l_cnt,		HOST_L_CNT);
+NVDIMM_EVENT_ATTR(host_s_cnt,		HOST_S_CNT);
+NVDIMM_EVENT_ATTR(host_s_dur,		HOST_S_DUR);
+NVDIMM_EVENT_ATTR(host_l_dur,		HOST_L_DUR);
+NVDIMM_EVENT_ATTR(med_r_cnt,		MED_R_CNT);
+NVDIMM_EVENT_ATTR(med_w_cnt,		MED_W_CNT);
+NVDIMM_EVENT_ATTR(med_r_dur,		MED_R_DUR);
+NVDIMM_EVENT_ATTR(med_w_dur,		MED_W_DUR);
+NVDIMM_EVENT_ATTR(cache_rh_cnt,		CACHE_RH_CNT);
+NVDIMM_EVENT_ATTR(cache_wh_cnt,		CACHE_WH_CNT);
+NVDIMM_EVENT_ATTR(fast_w_cnt,		FAST_W_CNT);
+
+static struct attribute *nvdimm_events_attr[] = {
+	NVDIMM_EVENT_PTR(CTL_RES_CNT),
+	NVDIMM_EVENT_PTR(CTL_RES_TM),
+	NVDIMM_EVENT_PTR(POWERON_SECS),
+	NVDIMM_EVENT_PTR(MEM_LIFE),
+	NVDIMM_EVENT_PTR(CRI_RES_UTIL),
+	NVDIMM_EVENT_PTR(HOST_L_CNT),
+	NVDIMM_EVENT_PTR(HOST_S_CNT),
+	NVDIMM_EVENT_PTR(HOST_S_DUR),
+	NVDIMM_EVENT_PTR(HOST_L_DUR),
+	NVDIMM_EVENT_PTR(MED_R_CNT),
+	NVDIMM_EVENT_PTR(MED_W_CNT),
+	NVDIMM_EVENT_PTR(MED_R_DUR),
+	NVDIMM_EVENT_PTR(MED_W_DUR),
+	NVDIMM_EVENT_PTR(CACHE_RH_CNT),
+	NVDIMM_EVENT_PTR(CACHE_WH_CNT),
+	NVDIMM_EVENT_PTR(FAST_W_CNT),
+	NULL
+};
+
+static struct attribute_group nvdimm_pmu_events_group = {
+	.name = "events",
+	.attrs = nvdimm_events_attr,
+};
+
+PMU_FORMAT_ATTR(event, "config:0-4");
+
+static struct attribute *nvdimm_pmu_format_attr[] = {
+	&format_attr_event.attr,
+	NULL,
+};
+
+static struct attribute_group nvdimm_pmu_format_group = {
+	.name = "format",
+	.attrs = nvdimm_pmu_format_attr,
+};
+
+ssize_t nvdimm_events_sysfs_show(struct device *dev,
+				 struct device_attribute *attr, char *page)
+{
+	struct perf_pmu_events_attr *pmu_attr;
+
+	pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr);
+
+	return sprintf(page, "event=0x%02llx\n", pmu_attr->id);
+}
+
+static ssize_t nvdimm_pmu_cpumask_show(struct device *dev,
+				       struct device_attribute *attr, char *buf)
+{
+	struct pmu *pmu = dev_get_drvdata(dev);
+	struct nvdimm_pmu *nd_pmu;
+
+	nd_pmu = container_of(pmu, struct nvdimm_pmu, pmu);
+
+	return cpumap_print_to_pagebuf(true, buf, cpumask_of(nd_pmu->cpu));
+}
+
+static int nvdimm_pmu_cpu_offline(unsigned int cpu, struct hlist_node *node)
+{
+	struct nvdimm_pmu *nd_pmu;
+	u32 target;
+	int nodeid;
+	const struct cpumask *cpumask;
+
+	nd_pmu = hlist_entry_safe(node, struct nvdimm_pmu, node);
+
+	/* Clear it, incase given cpu is set in nd_pmu->arch_cpumask */
+	cpumask_test_and_clear_cpu(cpu, &nd_pmu->arch_cpumask);
+
+	/*
+	 * If given cpu is not same as current designated cpu for
+	 * counter access, just return.
+	 */
+	if (cpu != nd_pmu->cpu)
+		return 0;
+
+	/* Check for any active cpu in nd_pmu->arch_cpumask */
+	target = cpumask_any(&nd_pmu->arch_cpumask);
+
+	/*
+	 * Incase we don't have any active cpu in nd_pmu->arch_cpumask,
+	 * check in given cpu's numa node list.
+	 */
+	if (target >= nr_cpu_ids) {
+		nodeid = cpu_to_node(cpu);
+		cpumask = cpumask_of_node(nodeid);
+		target = cpumask_any_but(cpumask, cpu);
+	}
+	nd_pmu->cpu = target;
+
+	/* Migrate nvdimm pmu events to the new target cpu if valid */
+	if (target >= 0 && target < nr_cpu_ids)
+		perf_pmu_migrate_context(&nd_pmu->pmu, cpu, target);
+
+	return 0;
+}
+
+static int nvdimm_pmu_cpu_online(unsigned int cpu, struct hlist_node *node)
+{
+	struct nvdimm_pmu *nd_pmu;
+
+	nd_pmu = hlist_entry_safe(node, struct nvdimm_pmu, node);
+
+	if (nd_pmu->cpu >= nr_cpu_ids)
+		nd_pmu->cpu = cpu;
+
+	return 0;
+}
+
+static int create_cpumask_attr_group(struct nvdimm_pmu *nd_pmu)
+{
+	struct perf_pmu_events_attr *pmu_events_attr;
+	struct attribute **attrs_group;
+	struct attribute_group *nvdimm_pmu_cpumask_group;
+
+	pmu_events_attr = kzalloc(sizeof(*pmu_events_attr), GFP_KERNEL);
+	if (!pmu_events_attr)
+		return -ENOMEM;
+
+	attrs_group = kzalloc(2 * sizeof(struct attribute *), GFP_KERNEL);
+	if (!attrs_group) {
+		kfree(pmu_events_attr);
+		return -ENOMEM;
+	}
+
+	/* Allocate memory for cpumask attribute group */
+	nvdimm_pmu_cpumask_group = kzalloc(sizeof(*nvdimm_pmu_cpumask_group), GFP_KERNEL);
+	if (!nvdimm_pmu_cpumask_group) {
+		kfree(pmu_events_attr);
+		kfree(attrs_group);
+		return -ENOMEM;
+	}
+
+	sysfs_attr_init(&pmu_events_attr->attr.attr);
+	pmu_events_attr->attr.attr.name = "cpumask";
+	pmu_events_attr->attr.attr.mode = 0444;
+	pmu_events_attr->attr.show = nvdimm_pmu_cpumask_show;
+	attrs_group[0] = &pmu_events_attr->attr.attr;
+	attrs_group[1] = NULL;
+
+	nvdimm_pmu_cpumask_group->attrs = attrs_group;
+	nd_pmu->pmu.attr_groups[NVDIMM_PMU_CPUMASK_ATTR] = nvdimm_pmu_cpumask_group;
+	return 0;
+}
+
+static int nvdimm_pmu_cpu_hotplug_init(struct nvdimm_pmu *nd_pmu)
+{
+	int nodeid, rc;
+	const struct cpumask *cpumask;
+
+	/*
+	 * Incase of cpu hotplug feature, arch specific code
+	 * can provide required cpumask which can be used
+	 * to get designatd cpu for counter access.
+	 * Check for any active cpu in nd_pmu->arch_cpumask.
+	 */
+	if (!cpumask_empty(&nd_pmu->arch_cpumask)) {
+		nd_pmu->cpu = cpumask_any(&nd_pmu->arch_cpumask);
+	} else {
+		/* pick active cpu from the cpumask of device numa node. */
+		nodeid = dev_to_node(nd_pmu->dev);
+		cpumask = cpumask_of_node(nodeid);
+		nd_pmu->cpu = cpumask_any(cpumask);
+	}
+
+	rc = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "perf/nvdimm:online",
+				     nvdimm_pmu_cpu_online, nvdimm_pmu_cpu_offline);
+
+	if (rc < 0)
+		return rc;
+
+	nd_pmu->cpuhp_state = rc;
+
+	/* Register the pmu instance for cpu hotplug */
+	rc = cpuhp_state_add_instance_nocalls(nd_pmu->cpuhp_state, &nd_pmu->node);
+	if (rc) {
+		cpuhp_remove_multi_state(nd_pmu->cpuhp_state);
+		return rc;
+	}
+
+	/* Create cpumask attribute group */
+	rc = create_cpumask_attr_group(nd_pmu);
+	if (rc) {
+		cpuhp_state_remove_instance_nocalls(nd_pmu->cpuhp_state, &nd_pmu->node);
+		cpuhp_remove_multi_state(nd_pmu->cpuhp_state);
+		return rc;
+	}
+
+	return 0;
+}
+
+static void nvdimm_pmu_free_hotplug_memory(struct nvdimm_pmu *nd_pmu)
+{
+	cpuhp_state_remove_instance_nocalls(nd_pmu->cpuhp_state, &nd_pmu->node);
+	cpuhp_remove_multi_state(nd_pmu->cpuhp_state);
+
+	if (nd_pmu->pmu.attr_groups[NVDIMM_PMU_CPUMASK_ATTR])
+		kfree(nd_pmu->pmu.attr_groups[NVDIMM_PMU_CPUMASK_ATTR]->attrs);
+	kfree(nd_pmu->pmu.attr_groups[NVDIMM_PMU_CPUMASK_ATTR]);
+}
+
+int register_nvdimm_pmu(struct nvdimm_pmu *nd_pmu, struct platform_device *pdev)
+{
+	int rc;
+
+	if (!nd_pmu || !pdev)
+		return -EINVAL;
+
+	/* event functions like add/del/read/event_init and pmu name should not be NULL */
+	if (WARN_ON_ONCE(!(nd_pmu->pmu.event_init && nd_pmu->pmu.add &&
+			   nd_pmu->pmu.del && nd_pmu->pmu.read && nd_pmu->pmu.name)))
+		return -EINVAL;
+
+	nd_pmu->pmu.attr_groups = kzalloc((NVDIMM_PMU_NULL_ATTR + 1) *
+					  sizeof(struct attribute_group *), GFP_KERNEL);
+	if (!nd_pmu->pmu.attr_groups)
+		return -ENOMEM;
+
+	/*
+	 * Add platform_device->dev pointer to nvdimm_pmu to access
+	 * device data in events functions.
+	 */
+	nd_pmu->dev = &pdev->dev;
+
+	/* Fill attribute groups for the nvdimm pmu device */
+	nd_pmu->pmu.attr_groups[NVDIMM_PMU_FORMAT_ATTR] = &nvdimm_pmu_format_group;
+	nd_pmu->pmu.attr_groups[NVDIMM_PMU_EVENT_ATTR] = &nvdimm_pmu_events_group;
+	nd_pmu->pmu.attr_groups[NVDIMM_PMU_NULL_ATTR] = NULL;
+
+	/* Fill attribute group for cpumask */
+	rc = nvdimm_pmu_cpu_hotplug_init(nd_pmu);
+	if (rc) {
+		pr_info("cpu hotplug feature failed for device: %s\n", nd_pmu->pmu.name);
+		kfree(nd_pmu->pmu.attr_groups);
+		return rc;
+	}
+
+	rc = perf_pmu_register(&nd_pmu->pmu, nd_pmu->pmu.name, -1);
+	if (rc) {
+		kfree(nd_pmu->pmu.attr_groups);
+		nvdimm_pmu_free_hotplug_memory(nd_pmu);
+		return rc;
+	}
+
+	pr_info("%s NVDIMM performance monitor support registered\n",
+		nd_pmu->pmu.name);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(register_nvdimm_pmu);
+
+void unregister_nvdimm_pmu(struct nvdimm_pmu *nd_pmu)
+{
+	perf_pmu_unregister(&nd_pmu->pmu);
+	nvdimm_pmu_free_hotplug_memory(nd_pmu);
+	kfree(nd_pmu);
+}
+EXPORT_SYMBOL_GPL(unregister_nvdimm_pmu);
diff --git a/include/linux/nd.h b/include/linux/nd.h
index f5ed4db2d859..fa4370607bdb 100644
--- a/include/linux/nd.h
+++ b/include/linux/nd.h
@@ -9,6 +9,7 @@ 
 #include <linux/device.h>
 #include <linux/badblocks.h>
 #include <linux/perf_event.h>
+#include <linux/platform_device.h>
 
 enum nvdimm_event {
 	NVDIMM_REVALIDATE_POISON,
@@ -24,6 +25,19 @@  enum nvdimm_claim_class {
 	NVDIMM_CCLASS_UNKNOWN,
 };
 
+#define NVDIMM_EVENT_VAR(_id)  event_attr_##_id
+#define NVDIMM_EVENT_PTR(_id)  (&event_attr_##_id.attr.attr)
+
+#define NVDIMM_EVENT_ATTR(_name, _id)				\
+	PMU_EVENT_ATTR(_name, NVDIMM_EVENT_VAR(_id), _id,	\
+			nvdimm_events_sysfs_show)
+
+/* Event attribute array index */
+#define NVDIMM_PMU_FORMAT_ATTR	0
+#define NVDIMM_PMU_EVENT_ATTR	1
+#define NVDIMM_PMU_CPUMASK_ATTR	2
+#define NVDIMM_PMU_NULL_ATTR	3
+
 /**
  * struct nvdimm_pmu - data structure for nvdimm perf driver
  * @pmu: pmu data structure for nvdimm performance stats.
@@ -43,6 +57,13 @@  struct nvdimm_pmu {
 	struct cpumask arch_cpumask;
 };
 
+extern ssize_t nvdimm_events_sysfs_show(struct device *dev,
+					struct device_attribute *attr,
+					char *page);
+
+int register_nvdimm_pmu(struct nvdimm_pmu *nvdimm, struct platform_device *pdev);
+void unregister_nvdimm_pmu(struct nvdimm_pmu *nd_pmu);
+
 struct nd_device_driver {
 	struct device_driver drv;
 	unsigned long type;