[PATCH V2 2/3] powercap: intel_rapl: Introduce APIs for PMU support

[Zhang Rui]

Introduce two new APIs rapl_package_add_pmu()/rapl_package_remove_pmu().

RAPL driver can invoke these APIs to expose its supported energy
counters via perf PMU. The new RAPL PMU is fully compatible with current
MSR RAPL PMU, including using the same PMU name and events
name/id/unit/scale, etc.

For example, use below command
 perf stat -e power/energy-pkg/ -e power/energy-ram/ -e power/energy-cores/ FOO
to get the energy consumption for events in the "perf list" output.

This does not introduce any conflict because TPMI RAPL is the only user
of these APIs currently, and it never co-exists with MSR RAPL.

Note that, TPMI RAPL is probed dynamically, and the events supported by
each TPMI RAPL device can be different. Thus, for a new RAPL Package
device that wants PMU support,
1. if PMU has not been registered yet, register the PMU with events
   supported by current RAPL Package device
2. if PMU has been registered and no new events support is needed, do
   nothing
2. or else, unregister current PMU and re-register the PMU with events
   supported by all probed RAPL Package devices that need PMU support.
   For example, on a dual-package system using TPMI RAPL, it is possible
   that Package 1 behaves as TPMI domain root and supports Psys domain.
   In this case, register PMU without Psys event when probing Package 0,
   and re-register the PMU with Psys event when probing Package 1.

Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
---
 drivers/powercap/intel_rapl_common.c | 537 +++++++++++++++++++++++++++
 include/linux/intel_rapl.h           |  23 ++
 2 files changed, 560 insertions(+)

diff --git a/drivers/powercap/intel_rapl_common.c b/drivers/powercap/intel_rapl_common.c
index 1f4a7aa12d77..f51012f023b0 100644
--- a/drivers/powercap/intel_rapl_common.c
+++ b/drivers/powercap/intel_rapl_common.c
@@ -15,6 +15,8 @@
 #include <linux/list.h>
 #include <linux/log2.h>
 #include <linux/module.h>
+#include <linux/nospec.h>
+#include <linux/perf_event.h>
 #include <linux/platform_device.h>
 #include <linux/powercap.h>
 #include <linux/processor.h>
@@ -1506,6 +1508,541 @@ static int rapl_detect_domains(struct rapl_package *rp)
 	return 0;
 }
 
+#ifdef CONFIG_PERF_EVENTS
+
+/* Support for RAPL PMU */
+
+struct rapl_pmu {
+	struct pmu pmu;
+	u64 timer_ms;
+	cpumask_t cpu_mask;
+	unsigned long domain_map;	/* Events supported by all registered RAPL packages */
+	bool registered;
+};
+
+static struct rapl_pmu rapl_pmu;
+
+/* PMU helpers */
+static int get_pmu_cpu(struct rapl_package *rp)
+{
+	int cpu;
+
+	if (!rp->has_pmu)
+		return nr_cpu_ids;
+
+	if (rp->lead_cpu >= 0)
+		return rp->lead_cpu;
+
+	/* TPMI RAPL uses any CPU in the package for PMU */
+	for_each_online_cpu(cpu)
+		if (topology_physical_package_id(cpu) == rp->id)
+			return cpu;
+
+	return nr_cpu_ids;
+}
+
+static bool is_rp_pmu_cpu(struct rapl_package *rp, int cpu)
+{
+	if (!rp->has_pmu)
+		return false;
+
+	if (rp->lead_cpu >= 0)
+		return cpu == rp->lead_cpu;
+
+	/* TPMI RAPL uses any CPU in the package for PMU */
+	return topology_physical_package_id(cpu) == rp->id;
+}
+
+static struct rapl_package_pmu_data *event_to_pmu_data(struct perf_event *event)
+{
+	struct rapl_package *rp = event->pmu_private;
+
+	return &rp->pmu_data;
+}
+
+/* PMU event callbacks */
+
+/* Return 0 for unsupported events or failed read */
+static u64 event_read_counter(struct perf_event *event)
+{
+	struct rapl_package *rp = event->pmu_private;
+	u64 val;
+	int ret;
+
+	if (event->hw.idx < 0)
+		return 0;
+
+	ret = rapl_read_data_raw(&rp->domains[event->hw.idx], ENERGY_COUNTER, false, &val);
+	return ret ? 0 : val;
+}
+
+static void __rapl_pmu_event_start(struct perf_event *event)
+{
+	struct rapl_package_pmu_data *data = event_to_pmu_data(event);
+
+	if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
+		return;
+
+	event->hw.state = 0;
+
+	list_add_tail(&event->active_entry, &data->active_list);
+
+	local64_set(&event->hw.prev_count, event_read_counter(event));
+	if (++data->n_active == 1)
+		hrtimer_start(&data->hrtimer, data->timer_interval,
+			      HRTIMER_MODE_REL_PINNED);
+}
+
+static void rapl_pmu_event_start(struct perf_event *event, int mode)
+{
+	struct rapl_package_pmu_data *data = event_to_pmu_data(event);
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&data->lock, flags);
+	__rapl_pmu_event_start(event);
+	raw_spin_unlock_irqrestore(&data->lock, flags);
+}
+
+static u64 rapl_event_update(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	struct rapl_package_pmu_data *data = event_to_pmu_data(event);
+	u64 prev_raw_count, new_raw_count;
+	s64 delta, sdelta;
+
+again:
+	prev_raw_count = local64_read(&hwc->prev_count);
+	new_raw_count = event_read_counter(event);
+
+	if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
+			new_raw_count) != prev_raw_count)
+		goto again;
+
+	/*
+	 * Now we have the new raw value and have updated the prev
+	 * timestamp already. We can now calculate the elapsed delta
+	 * (event-)time and add that to the generic event.
+	 */
+	delta = new_raw_count - prev_raw_count;
+
+	/*
+	 * Scale delta to smallest unit (2^-32)
+	 * users must then scale back: count * 1/(1e9*2^32) to get Joules
+	 * or use ldexp(count, -32).
+	 * Watts = Joules/Time delta
+	 */
+	sdelta = delta * data->scale[event->hw.flags];
+
+	local64_add(sdelta, &event->count);
+
+	return new_raw_count;
+}
+
+static void rapl_pmu_event_stop(struct perf_event *event, int mode)
+{
+	struct rapl_package_pmu_data *data = event_to_pmu_data(event);
+	struct hw_perf_event *hwc = &event->hw;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&data->lock, flags);
+
+	/* Mark event as deactivated and stopped */
+	if (!(hwc->state & PERF_HES_STOPPED)) {
+		WARN_ON_ONCE(data->n_active <= 0);
+		if (--data->n_active == 0)
+			hrtimer_cancel(&data->hrtimer);
+
+		list_del(&event->active_entry);
+
+		WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
+		hwc->state |= PERF_HES_STOPPED;
+	}
+
+	/* Check if update of sw counter is necessary */
+	if ((mode & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) {
+		/*
+		 * Drain the remaining delta count out of a event
+		 * that we are disabling:
+		 */
+		rapl_event_update(event);
+		hwc->state |= PERF_HES_UPTODATE;
+	}
+
+	raw_spin_unlock_irqrestore(&data->lock, flags);
+}
+
+static int rapl_pmu_event_add(struct perf_event *event, int mode)
+{
+	struct rapl_package_pmu_data *data = event_to_pmu_data(event);
+	struct hw_perf_event *hwc = &event->hw;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&data->lock, flags);
+
+	hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
+
+	if (mode & PERF_EF_START)
+		__rapl_pmu_event_start(event);
+
+	raw_spin_unlock_irqrestore(&data->lock, flags);
+
+	return 0;
+}
+
+static void rapl_pmu_event_del(struct perf_event *event, int flags)
+{
+	rapl_pmu_event_stop(event, PERF_EF_UPDATE);
+}
+
+/*
+ * RAPL energy status counters
+ */
+enum perf_rapl_events {
+	PERF_RAPL_PP0 = 0,	/* all cores */
+	PERF_RAPL_PKG,		/* entire package */
+	PERF_RAPL_RAM,		/* DRAM */
+	PERF_RAPL_PP1,		/* gpu */
+	PERF_RAPL_PSYS,		/* psys */
+};
+#define RAPL_EVENT_MASK GENMASK(7, 0)
+
+static int event_to_domain(int event)
+{
+	switch (event) {
+	case PERF_RAPL_PP0:
+		return RAPL_DOMAIN_PP0;
+	case PERF_RAPL_PKG:
+		return RAPL_DOMAIN_PACKAGE;
+	case PERF_RAPL_RAM:
+		return RAPL_DOMAIN_DRAM;
+	case PERF_RAPL_PP1:
+		return RAPL_DOMAIN_PP1;
+	case PERF_RAPL_PSYS:
+		return RAPL_DOMAIN_PLATFORM;
+	default:
+		return RAPL_DOMAIN_MAX;
+	}
+}
+
+static int rapl_pmu_event_init(struct perf_event *event)
+{
+	struct rapl_package *pos, *rp = NULL;
+	u64 cfg = event->attr.config & RAPL_EVENT_MASK;
+	int domain, idx;
+
+	/* Only look at RAPL events */
+	if (event->attr.type != event->pmu->type)
+		return -ENOENT;
+
+	/* Check only supported bits are set */
+	if (event->attr.config & ~RAPL_EVENT_MASK)
+		return -EINVAL;
+
+	if (event->cpu < 0)
+		return -EINVAL;
+
+	/* Find out which Package the event belongs to */
+	list_for_each_entry(pos, &rapl_packages, plist) {
+		if (is_rp_pmu_cpu(pos, event->cpu)) {
+			rp = pos;
+			break;
+		}
+	}
+	if (!rp)
+		return -ENODEV;
+
+	/* Find out which RAPL Domain the event belongs to */
+	domain = event_to_domain(cfg - 1);
+	if (domain >= RAPL_DOMAIN_MAX)
+		return -EINVAL;
+
+	event->event_caps |= PERF_EV_CAP_READ_ACTIVE_PKG;
+	event->pmu_private = rp;	/* Which package */
+	event->hw.flags = domain;	/* Which domain */
+
+	event->hw.idx = -1;
+	/* Find out the index in rp->domains[] to get domain pointer */
+	for (idx = 0; idx < rp->nr_domains; idx++) {
+		if (rp->domains[idx].id == domain) {
+			event->hw.idx = idx;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static void rapl_pmu_event_read(struct perf_event *event)
+{
+	rapl_event_update(event);
+}
+
+static enum hrtimer_restart rapl_hrtimer_handle(struct hrtimer *hrtimer)
+{
+	struct rapl_package_pmu_data *data =
+		container_of(hrtimer, struct rapl_package_pmu_data, hrtimer);
+	struct perf_event *event;
+	unsigned long flags;
+
+	if (!data->n_active)
+		return HRTIMER_NORESTART;
+
+	raw_spin_lock_irqsave(&data->lock, flags);
+
+	list_for_each_entry(event, &data->active_list, active_entry)
+		rapl_event_update(event);
+
+	raw_spin_unlock_irqrestore(&data->lock, flags);
+
+	hrtimer_forward_now(hrtimer, data->timer_interval);
+
+	return HRTIMER_RESTART;
+}
+
+/* PMU sysfs attributes */
+
+/*
+ * There are no default events, but we need to create "events" group (with
+ * empty attrs) before updating it with detected events.
+ */
+static struct attribute *attrs_empty[] = {
+	NULL,
+};
+
+static struct attribute_group pmu_events_group = {
+	.name = "events",
+	.attrs = attrs_empty,
+};
+
+static ssize_t cpumask_show(struct device *dev,
+			    struct device_attribute *attr, char *buf)
+{
+	struct rapl_package *rp;
+	int cpu;
+
+	cpus_read_lock();
+	cpumask_clear(&rapl_pmu.cpu_mask);
+
+	/* Choose a cpu for each RAPL Package */
+	list_for_each_entry(rp, &rapl_packages, plist) {
+		cpu = get_pmu_cpu(rp);
+		if (cpu < nr_cpu_ids)
+			cpumask_set_cpu(cpu, &rapl_pmu.cpu_mask);
+	}
+	cpus_read_unlock();
+
+	return cpumap_print_to_pagebuf(true, buf, &rapl_pmu.cpu_mask);
+}
+
+static DEVICE_ATTR_RO(cpumask);
+
+static struct attribute *pmu_cpumask_attrs[] = {
+	&dev_attr_cpumask.attr,
+	NULL
+};
+
+static struct attribute_group pmu_cpumask_group = {
+	.attrs = pmu_cpumask_attrs,
+};
+
+PMU_FORMAT_ATTR(event, "config:0-7");
+static struct attribute *pmu_format_attr[] = {
+	&format_attr_event.attr,
+	NULL
+};
+
+static struct attribute_group pmu_format_group = {
+	.name = "format",
+	.attrs = pmu_format_attr,
+};
+
+static const struct attribute_group *pmu_attr_groups[] = {
+	&pmu_events_group,
+	&pmu_cpumask_group,
+	&pmu_format_group,
+	NULL
+};
+
+#define RAPL_EVENT_ATTR_STR(_name, v, str)					\
+static struct perf_pmu_events_attr event_attr_##v = {				\
+	.attr		= __ATTR(_name, 0444, perf_event_sysfs_show, NULL),	\
+	.event_str	= str,							\
+}
+
+RAPL_EVENT_ATTR_STR(energy-cores,	rapl_cores,	"event=0x01");
+RAPL_EVENT_ATTR_STR(energy-pkg,		rapl_pkg,	"event=0x02");
+RAPL_EVENT_ATTR_STR(energy-ram,		rapl_ram,	"event=0x03");
+RAPL_EVENT_ATTR_STR(energy-gpu,		rapl_gpu,	"event=0x04");
+RAPL_EVENT_ATTR_STR(energy-psys,	rapl_psys,	"event=0x05");
+
+RAPL_EVENT_ATTR_STR(energy-cores.unit,	rapl_unit_cores,	"Joules");
+RAPL_EVENT_ATTR_STR(energy-pkg.unit,	rapl_unit_pkg,		"Joules");
+RAPL_EVENT_ATTR_STR(energy-ram.unit,	rapl_unit_ram,		"Joules");
+RAPL_EVENT_ATTR_STR(energy-gpu.unit,	rapl_unit_gpu,		"Joules");
+RAPL_EVENT_ATTR_STR(energy-psys.unit,	rapl_unit_psys,		"Joules");
+
+RAPL_EVENT_ATTR_STR(energy-cores.scale,	rapl_scale_cores,	"2.3283064365386962890625e-10");
+RAPL_EVENT_ATTR_STR(energy-pkg.scale,	rapl_scale_pkg,		"2.3283064365386962890625e-10");
+RAPL_EVENT_ATTR_STR(energy-ram.scale,	rapl_scale_ram,		"2.3283064365386962890625e-10");
+RAPL_EVENT_ATTR_STR(energy-gpu.scale,	rapl_scale_gpu,		"2.3283064365386962890625e-10");
+RAPL_EVENT_ATTR_STR(energy-psys.scale,	rapl_scale_psys,	"2.3283064365386962890625e-10");
+
+#define RAPL_EVENT_GROUP(_name, domain)			\
+static struct attribute *pmu_attr_##_name[] = {		\
+	&event_attr_rapl_##_name.attr.attr,		\
+	&event_attr_rapl_unit_##_name.attr.attr,	\
+	&event_attr_rapl_scale_##_name.attr.attr,	\
+	NULL						\
+};							\
+static umode_t is_visible_##_name(struct kobject *kobj, struct attribute *attr, int event)	\
+{											\
+	return rapl_pmu.domain_map & BIT(domain) ? attr->mode : 0;	\
+}							\
+static struct attribute_group pmu_group_##_name = {	\
+	.name  = "events",				\
+	.attrs = pmu_attr_##_name,			\
+	.is_visible = is_visible_##_name,		\
+}
+
+RAPL_EVENT_GROUP(cores,	RAPL_DOMAIN_PP0);
+RAPL_EVENT_GROUP(pkg,	RAPL_DOMAIN_PACKAGE);
+RAPL_EVENT_GROUP(ram,	RAPL_DOMAIN_DRAM);
+RAPL_EVENT_GROUP(gpu,	RAPL_DOMAIN_PP1);
+RAPL_EVENT_GROUP(psys,	RAPL_DOMAIN_PLATFORM);
+
+static const struct attribute_group *pmu_attr_update[] = {
+	&pmu_group_cores,
+	&pmu_group_pkg,
+	&pmu_group_ram,
+	&pmu_group_gpu,
+	&pmu_group_psys,
+	NULL
+};
+
+static int rapl_pmu_update(struct rapl_package *rp)
+{
+	int ret;
+
+	/* Return if PMU already covers all events supported by current RAPL Package */
+	if (rapl_pmu.registered && !(rp->domain_map & (~rapl_pmu.domain_map)))
+		return 0;
+
+	/* Unregister previous registered PMU */
+	if (rapl_pmu.registered) {
+		perf_pmu_unregister(&rapl_pmu.pmu);
+		memset(&rapl_pmu.pmu, 0, sizeof(struct pmu));
+	}
+
+	rapl_pmu.domain_map |= rp->domain_map;
+
+	memset(&rapl_pmu.pmu, 0, sizeof(struct pmu));
+	rapl_pmu.pmu.attr_groups = pmu_attr_groups;
+	rapl_pmu.pmu.attr_update = pmu_attr_update;
+	rapl_pmu.pmu.task_ctx_nr = perf_invalid_context;
+	rapl_pmu.pmu.event_init = rapl_pmu_event_init;
+	rapl_pmu.pmu.add = rapl_pmu_event_add;
+	rapl_pmu.pmu.del = rapl_pmu_event_del;
+	rapl_pmu.pmu.start = rapl_pmu_event_start;
+	rapl_pmu.pmu.stop = rapl_pmu_event_stop;
+	rapl_pmu.pmu.read = rapl_pmu_event_read;
+	rapl_pmu.pmu.module = THIS_MODULE;
+	rapl_pmu.pmu.capabilities = PERF_PMU_CAP_NO_EXCLUDE | PERF_PMU_CAP_NO_INTERRUPT;
+	ret = perf_pmu_register(&rapl_pmu.pmu, "power", -1);
+	if (ret)
+		pr_warn("Failed to register PMU\n");
+
+	rapl_pmu.registered = !ret;
+
+	return ret;
+}
+
+int rapl_package_add_pmu(struct rapl_package *rp)
+{
+	struct rapl_package_pmu_data *data = &rp->pmu_data;
+	int idx;
+	int ret;
+
+	if (rp->has_pmu)
+		return -EEXIST;
+
+	guard(cpus_read_lock)();
+
+	for (idx = 0; idx < rp->nr_domains; idx++) {
+		struct rapl_domain *rd = &rp->domains[idx];
+		int domain = rd->id;
+		u64 val;
+
+		if (!test_bit(domain, &rp->domain_map))
+			continue;
+
+		/*
+		 * The RAPL PMU granularity is 2^-32 Joules
+		 * data->scale[]: times of 2^-32 Joules for each ENERGY COUNTER increase
+		 */
+		val = rd->energy_unit * (1ULL << 32);
+		do_div(val, ENERGY_UNIT_SCALE * 1000000);
+		data->scale[domain] = val;
+
+		if (!rapl_pmu.timer_ms) {
+			struct rapl_primitive_info *rpi = get_rpi(rp, ENERGY_COUNTER);
+
+			/*
+			 * Calculate the timer rate:
+			 * Use reference of 200W for scaling the timeout to avoid counter
+			 * overflows.
+			 *
+			 * max_count = rpi->mask >> rpi->shift + 1
+			 * max_energy_pj = max_count * rd->energy_unit
+			 * max_time_sec = (max_energy_pj / 1000000000) / 200w
+			 *
+			 * rapl_pmu.timer_ms = max_time_sec * 1000 / 2
+			 */
+			val = (rpi->mask >> rpi->shift) + 1;
+			val *= rd->energy_unit;
+			do_div(val, 1000000 * 200 * 2);
+			rapl_pmu.timer_ms = val;
+
+			pr_info("%llu ms ovfl timer\n", rapl_pmu.timer_ms);
+		}
+
+		pr_info("Domain %s: hw unit %lld * 2^-32 Joules\n", rd->name, data->scale[domain]);
+	}
+
+	/* Initialize per package PMU data */
+	raw_spin_lock_init(&data->lock);
+	INIT_LIST_HEAD(&data->active_list);
+	data->timer_interval = ms_to_ktime(rapl_pmu.timer_ms);
+	hrtimer_init(&data->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	data->hrtimer.function = rapl_hrtimer_handle;
+
+	ret = rapl_pmu_update(rp);
+	if (!ret)
+		rp->has_pmu = true;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rapl_package_add_pmu);
+
+void rapl_package_remove_pmu(struct rapl_package *rp)
+{
+	struct rapl_package *pos;
+
+	if (!rp->has_pmu)
+		return;
+
+	guard(cpus_read_lock)();
+
+	list_for_each_entry(pos, &rapl_packages, plist) {
+		/* PMU is still needed */
+		if (pos->has_pmu)
+			return;
+	}
+
+	perf_pmu_unregister(&rapl_pmu.pmu);
+	memset(&rapl_pmu, 0, sizeof(struct rapl_pmu));
+}
+EXPORT_SYMBOL_GPL(rapl_package_remove_pmu);
+#endif
+
 /* called from CPU hotplug notifier, hotplug lock held */
 void rapl_remove_package_cpuslocked(struct rapl_package *rp)
 {
diff --git a/include/linux/intel_rapl.h b/include/linux/intel_rapl.h
index f3196f82fd8a..38e43dbb3dac 100644
--- a/include/linux/intel_rapl.h
+++ b/include/linux/intel_rapl.h
@@ -158,6 +158,17 @@ struct rapl_if_priv {
 	void *rpi;
 };
 
+#ifdef CONFIG_PERF_EVENTS
+struct rapl_package_pmu_data {
+	u64 scale[RAPL_DOMAIN_MAX];
+	raw_spinlock_t lock;
+	int n_active;
+	struct list_head active_list;
+	ktime_t timer_interval;
+	struct hrtimer hrtimer;
+};
+#endif
+
 /* maximum rapl package domain name: package-%d-die-%d */
 #define PACKAGE_DOMAIN_NAME_LENGTH 30
 
@@ -176,6 +187,10 @@ struct rapl_package {
 	struct cpumask cpumask;
 	char name[PACKAGE_DOMAIN_NAME_LENGTH];
 	struct rapl_if_priv *priv;
+#ifdef CONFIG_PERF_EVENTS
+	bool has_pmu;
+	struct rapl_package_pmu_data pmu_data;
+#endif
 };
 
 struct rapl_package *rapl_find_package_domain_cpuslocked(int id, struct rapl_if_priv *priv,
@@ -188,4 +203,12 @@ struct rapl_package *rapl_find_package_domain(int id, struct rapl_if_priv *priv,
 struct rapl_package *rapl_add_package(int id, struct rapl_if_priv *priv, bool id_is_cpu);
 void rapl_remove_package(struct rapl_package *rp);
 
+#ifdef CONFIG_PERF_EVENTS
+int rapl_package_add_pmu(struct rapl_package *rp);
+void rapl_package_remove_pmu(struct rapl_package *rp);
+#else
+static inline int rapl_package_add_pmu(struct rapl_package *rp) { return 0; }
+static inline void rapl_package_remove_pmu(struct rapl_package *rp) { }
+#endif
+
 #endif /* __INTEL_RAPL_H__ */
-- 
2.34.1