Linux 4.19.133

[linux/fpc-iii.git] / drivers / gpu / drm / i915 / i915_pmu.c

/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright © 2017-2018 Intel Corporation
 */

#include <linux/irq.h>
#include "i915_pmu.h"
#include "intel_ringbuffer.h"
#include "i915_drv.h"

/* Frequency for the sampling timer for events which need it. */
#define FREQUENCY 200
#define PERIOD max_t(u64, 10000, NSEC_PER_SEC / FREQUENCY)

#define ENGINE_SAMPLE_MASK \
        (BIT(I915_SAMPLE_BUSY) | \
         BIT(I915_SAMPLE_WAIT) | \
         BIT(I915_SAMPLE_SEMA))

#define ENGINE_SAMPLE_BITS (1 << I915_PMU_SAMPLE_BITS)

static cpumask_t i915_pmu_cpumask;

static u8 engine_config_sample(u64 config)
{
        return config & I915_PMU_SAMPLE_MASK;
}

static u8 engine_event_sample(struct perf_event *event)
{
        return engine_config_sample(event->attr.config);
}

static u8 engine_event_class(struct perf_event *event)
{
        return (event->attr.config >> I915_PMU_CLASS_SHIFT) & 0xff;
}

static u8 engine_event_instance(struct perf_event *event)
{
        return (event->attr.config >> I915_PMU_SAMPLE_BITS) & 0xff;
}

static bool is_engine_config(u64 config)
{
        return config < __I915_PMU_OTHER(0);
}

static unsigned int config_enabled_bit(u64 config)
{
        if (is_engine_config(config))
                return engine_config_sample(config);
        else
                return ENGINE_SAMPLE_BITS + (config - __I915_PMU_OTHER(0));
}

static u64 config_enabled_mask(u64 config)
{
        return BIT_ULL(config_enabled_bit(config));
}

static bool is_engine_event(struct perf_event *event)
{
        return is_engine_config(event->attr.config);
}

static unsigned int event_enabled_bit(struct perf_event *event)
{
        return config_enabled_bit(event->attr.config);
}

static bool pmu_needs_timer(struct drm_i915_private *i915, bool gpu_active)
{
        u64 enable;

        /*
         * Only some counters need the sampling timer.
         *
         * We start with a bitmask of all currently enabled events.
         */
        enable = i915->pmu.enable;

        /*
         * Mask out all the ones which do not need the timer, or in
         * other words keep all the ones that could need the timer.
         */
        enable &= config_enabled_mask(I915_PMU_ACTUAL_FREQUENCY) |
                  config_enabled_mask(I915_PMU_REQUESTED_FREQUENCY) |
                  ENGINE_SAMPLE_MASK;

        /*
         * When the GPU is idle per-engine counters do not need to be
         * running so clear those bits out.
         */
        if (!gpu_active)
                enable &= ~ENGINE_SAMPLE_MASK;
        /*
         * Also there is software busyness tracking available we do not
         * need the timer for I915_SAMPLE_BUSY counter.
         *
         * Use RCS as proxy for all engines.
         */
        else if (intel_engine_supports_stats(i915->engine[RCS]))
                enable &= ~BIT(I915_SAMPLE_BUSY);

        /*
         * If some bits remain it means we need the sampling timer running.
         */
        return enable;
}

void i915_pmu_gt_parked(struct drm_i915_private *i915)
{
        if (!i915->pmu.base.event_init)
                return;

        spin_lock_irq(&i915->pmu.lock);
        /*
         * Signal sampling timer to stop if only engine events are enabled and
         * GPU went idle.
         */
        i915->pmu.timer_enabled = pmu_needs_timer(i915, false);
        spin_unlock_irq(&i915->pmu.lock);
}

static void __i915_pmu_maybe_start_timer(struct drm_i915_private *i915)
{
        if (!i915->pmu.timer_enabled && pmu_needs_timer(i915, true)) {
                i915->pmu.timer_enabled = true;
                i915->pmu.timer_last = ktime_get();
                hrtimer_start_range_ns(&i915->pmu.timer,
                                       ns_to_ktime(PERIOD), 0,
                                       HRTIMER_MODE_REL_PINNED);
        }
}

void i915_pmu_gt_unparked(struct drm_i915_private *i915)
{
        if (!i915->pmu.base.event_init)
                return;

        spin_lock_irq(&i915->pmu.lock);
        /*
         * Re-enable sampling timer when GPU goes active.
         */
        __i915_pmu_maybe_start_timer(i915);
        spin_unlock_irq(&i915->pmu.lock);
}

static bool grab_forcewake(struct drm_i915_private *i915, bool fw)
{
        if (!fw)
                intel_uncore_forcewake_get(i915, FORCEWAKE_ALL);

        return true;
}

static void
add_sample(struct i915_pmu_sample *sample, u32 val)
{
        sample->cur += val;
}

static void
engines_sample(struct drm_i915_private *dev_priv, unsigned int period_ns)
{
        struct intel_engine_cs *engine;
        enum intel_engine_id id;
        bool fw = false;

        if ((dev_priv->pmu.enable & ENGINE_SAMPLE_MASK) == 0)
                return;

        if (!dev_priv->gt.awake)
                return;

        if (!intel_runtime_pm_get_if_in_use(dev_priv))
                return;

        for_each_engine(engine, dev_priv, id) {
                u32 current_seqno = intel_engine_get_seqno(engine);
                u32 last_seqno = intel_engine_last_submit(engine);
                u32 val;

                val = !i915_seqno_passed(current_seqno, last_seqno);

                if (val)
                        add_sample(&engine->pmu.sample[I915_SAMPLE_BUSY],
                                   period_ns);

                if (val && (engine->pmu.enable &
                    (BIT(I915_SAMPLE_WAIT) | BIT(I915_SAMPLE_SEMA)))) {
                        fw = grab_forcewake(dev_priv, fw);

                        val = I915_READ_FW(RING_CTL(engine->mmio_base));
                } else {
                        val = 0;
                }

                if (val & RING_WAIT)
                        add_sample(&engine->pmu.sample[I915_SAMPLE_WAIT],
                                   period_ns);

                if (val & RING_WAIT_SEMAPHORE)
                        add_sample(&engine->pmu.sample[I915_SAMPLE_SEMA],
                                   period_ns);
        }

        if (fw)
                intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);

        intel_runtime_pm_put(dev_priv);
}

static void
add_sample_mult(struct i915_pmu_sample *sample, u32 val, u32 mul)
{
        sample->cur += mul_u32_u32(val, mul);
}

static void
frequency_sample(struct drm_i915_private *dev_priv, unsigned int period_ns)
{
        if (dev_priv->pmu.enable &
            config_enabled_mask(I915_PMU_ACTUAL_FREQUENCY)) {
                u32 val;

                val = dev_priv->gt_pm.rps.cur_freq;
                if (dev_priv->gt.awake &&
                    intel_runtime_pm_get_if_in_use(dev_priv)) {
                        val = intel_get_cagf(dev_priv,
                                             I915_READ_NOTRACE(GEN6_RPSTAT1));
                        intel_runtime_pm_put(dev_priv);
                }

                add_sample_mult(&dev_priv->pmu.sample[__I915_SAMPLE_FREQ_ACT],
                                intel_gpu_freq(dev_priv, val),
                                period_ns / 1000);
        }

        if (dev_priv->pmu.enable &
            config_enabled_mask(I915_PMU_REQUESTED_FREQUENCY)) {
                add_sample_mult(&dev_priv->pmu.sample[__I915_SAMPLE_FREQ_REQ],
                                intel_gpu_freq(dev_priv,
                                               dev_priv->gt_pm.rps.cur_freq),
                                period_ns / 1000);
        }
}

static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer)
{
        struct drm_i915_private *i915 =
                container_of(hrtimer, struct drm_i915_private, pmu.timer);
        unsigned int period_ns;
        ktime_t now;

        if (!READ_ONCE(i915->pmu.timer_enabled))
                return HRTIMER_NORESTART;

        now = ktime_get();
        period_ns = ktime_to_ns(ktime_sub(now, i915->pmu.timer_last));
        i915->pmu.timer_last = now;

        /*
         * Strictly speaking the passed in period may not be 100% accurate for
         * all internal calculation, since some amount of time can be spent on
         * grabbing the forcewake. However the potential error from timer call-
         * back delay greatly dominates this so we keep it simple.
         */
        engines_sample(i915, period_ns);
        frequency_sample(i915, period_ns);

        hrtimer_forward(hrtimer, now, ns_to_ktime(PERIOD));

        return HRTIMER_RESTART;
}

static u64 count_interrupts(struct drm_i915_private *i915)
{
        /* open-coded kstat_irqs() */
        struct irq_desc *desc = irq_to_desc(i915->drm.pdev->irq);
        u64 sum = 0;
        int cpu;

        if (!desc || !desc->kstat_irqs)
                return 0;

        for_each_possible_cpu(cpu)
                sum += *per_cpu_ptr(desc->kstat_irqs, cpu);

        return sum;
}

static void engine_event_destroy(struct perf_event *event)
{
        struct drm_i915_private *i915 =
                container_of(event->pmu, typeof(*i915), pmu.base);
        struct intel_engine_cs *engine;

        engine = intel_engine_lookup_user(i915,
                                          engine_event_class(event),
                                          engine_event_instance(event));
        if (WARN_ON_ONCE(!engine))
                return;

        if (engine_event_sample(event) == I915_SAMPLE_BUSY &&
            intel_engine_supports_stats(engine))
                intel_disable_engine_stats(engine);
}

static void i915_pmu_event_destroy(struct perf_event *event)
{
        WARN_ON(event->parent);

        if (is_engine_event(event))
                engine_event_destroy(event);
}

static int
engine_event_status(struct intel_engine_cs *engine,
                    enum drm_i915_pmu_engine_sample sample)
{
        switch (sample) {
        case I915_SAMPLE_BUSY:
        case I915_SAMPLE_WAIT:
                break;
        case I915_SAMPLE_SEMA:
                if (INTEL_GEN(engine->i915) < 6)
                        return -ENODEV;
                break;
        default:
                return -ENOENT;
        }

        return 0;
}

static int
config_status(struct drm_i915_private *i915, u64 config)
{
        switch (config) {
        case I915_PMU_ACTUAL_FREQUENCY:
                if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915))
                        /* Requires a mutex for sampling! */
                        return -ENODEV;
                /* Fall-through. */
        case I915_PMU_REQUESTED_FREQUENCY:
                if (INTEL_GEN(i915) < 6)
                        return -ENODEV;
                break;
        case I915_PMU_INTERRUPTS:
                break;
        case I915_PMU_RC6_RESIDENCY:
                if (!HAS_RC6(i915))
                        return -ENODEV;
                break;
        default:
                return -ENOENT;
        }

        return 0;
}

static int engine_event_init(struct perf_event *event)
{
        struct drm_i915_private *i915 =
                container_of(event->pmu, typeof(*i915), pmu.base);
        struct intel_engine_cs *engine;
        u8 sample;
        int ret;

        engine = intel_engine_lookup_user(i915, engine_event_class(event),
                                          engine_event_instance(event));
        if (!engine)
                return -ENODEV;

        sample = engine_event_sample(event);
        ret = engine_event_status(engine, sample);
        if (ret)
                return ret;

        if (sample == I915_SAMPLE_BUSY && intel_engine_supports_stats(engine))
                ret = intel_enable_engine_stats(engine);

        return ret;
}

static int i915_pmu_event_init(struct perf_event *event)
{
        struct drm_i915_private *i915 =
                container_of(event->pmu, typeof(*i915), pmu.base);
        int ret;

        if (event->attr.type != event->pmu->type)
                return -ENOENT;

        /* unsupported modes and filters */
        if (event->attr.sample_period) /* no sampling */
                return -EINVAL;

        if (has_branch_stack(event))
                return -EOPNOTSUPP;

        if (event->cpu < 0)
                return -EINVAL;

        /* only allow running on one cpu at a time */
        if (!cpumask_test_cpu(event->cpu, &i915_pmu_cpumask))
                return -EINVAL;

        if (is_engine_event(event))
                ret = engine_event_init(event);
        else
                ret = config_status(i915, event->attr.config);
        if (ret)
                return ret;

        if (!event->parent)
                event->destroy = i915_pmu_event_destroy;

        return 0;
}

static u64 __get_rc6(struct drm_i915_private *i915)
{
        u64 val;

        val = intel_rc6_residency_ns(i915,
                                     IS_VALLEYVIEW(i915) ?
                                     VLV_GT_RENDER_RC6 :
                                     GEN6_GT_GFX_RC6);

        if (HAS_RC6p(i915))
                val += intel_rc6_residency_ns(i915, GEN6_GT_GFX_RC6p);

        if (HAS_RC6pp(i915))
                val += intel_rc6_residency_ns(i915, GEN6_GT_GFX_RC6pp);

        return val;
}

static u64 get_rc6(struct drm_i915_private *i915)
{
#if IS_ENABLED(CONFIG_PM)
        unsigned long flags;
        u64 val;

        if (intel_runtime_pm_get_if_in_use(i915)) {
                val = __get_rc6(i915);
                intel_runtime_pm_put(i915);

                /*
                 * If we are coming back from being runtime suspended we must
                 * be careful not to report a larger value than returned
                 * previously.
                 */

                spin_lock_irqsave(&i915->pmu.lock, flags);

                if (val >= i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur) {
                        i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur = 0;
                        i915->pmu.sample[__I915_SAMPLE_RC6].cur = val;
                } else {
                        val = i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur;
                }

                spin_unlock_irqrestore(&i915->pmu.lock, flags);
        } else {
                struct pci_dev *pdev = i915->drm.pdev;
                struct device *kdev = &pdev->dev;

                /*
                 * We are runtime suspended.
                 *
                 * Report the delta from when the device was suspended to now,
                 * on top of the last known real value, as the approximated RC6
                 * counter value.
                 */
                spin_lock_irqsave(&i915->pmu.lock, flags);
                spin_lock(&kdev->power.lock);

                /*
                 * After the above branch intel_runtime_pm_get_if_in_use failed
                 * to get the runtime PM reference we cannot assume we are in
                 * runtime suspend since we can either: a) race with coming out
                 * of it before we took the power.lock, or b) there are other
                 * states than suspended which can bring us here.
                 *
                 * We need to double-check that we are indeed currently runtime
                 * suspended and if not we cannot do better than report the last
                 * known RC6 value.
                 */
                if (kdev->power.runtime_status == RPM_SUSPENDED) {
                        if (!i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur)
                                i915->pmu.suspended_jiffies_last =
                                                  kdev->power.suspended_jiffies;

                        val = kdev->power.suspended_jiffies -
                              i915->pmu.suspended_jiffies_last;
                        val += jiffies - kdev->power.accounting_timestamp;

                        val = jiffies_to_nsecs(val);
                        val += i915->pmu.sample[__I915_SAMPLE_RC6].cur;

                        i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur = val;
                } else if (i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur) {
                        val = i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur;
                } else {
                        val = i915->pmu.sample[__I915_SAMPLE_RC6].cur;
                }

                spin_unlock(&kdev->power.lock);
                spin_unlock_irqrestore(&i915->pmu.lock, flags);
        }

        return val;
#else
        return __get_rc6(i915);
#endif
}

static u64 __i915_pmu_event_read(struct perf_event *event)
{
        struct drm_i915_private *i915 =
                container_of(event->pmu, typeof(*i915), pmu.base);
        u64 val = 0;

        if (is_engine_event(event)) {
                u8 sample = engine_event_sample(event);
                struct intel_engine_cs *engine;

                engine = intel_engine_lookup_user(i915,
                                                  engine_event_class(event),
                                                  engine_event_instance(event));

                if (WARN_ON_ONCE(!engine)) {
                        /* Do nothing */
                } else if (sample == I915_SAMPLE_BUSY &&
                           intel_engine_supports_stats(engine)) {
                        val = ktime_to_ns(intel_engine_get_busy_time(engine));
                } else {
                        val = engine->pmu.sample[sample].cur;
                }
        } else {
                switch (event->attr.config) {
                case I915_PMU_ACTUAL_FREQUENCY:
                        val =
                           div_u64(i915->pmu.sample[__I915_SAMPLE_FREQ_ACT].cur,
                                   USEC_PER_SEC /* to MHz */);
                        break;
                case I915_PMU_REQUESTED_FREQUENCY:
                        val =
                           div_u64(i915->pmu.sample[__I915_SAMPLE_FREQ_REQ].cur,
                                   USEC_PER_SEC /* to MHz */);
                        break;
                case I915_PMU_INTERRUPTS:
                        val = count_interrupts(i915);
                        break;
                case I915_PMU_RC6_RESIDENCY:
                        val = get_rc6(i915);
                        break;
                }
        }

        return val;
}

static void i915_pmu_event_read(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        u64 prev, new;

again:
        prev = local64_read(&hwc->prev_count);
        new = __i915_pmu_event_read(event);

        if (local64_cmpxchg(&hwc->prev_count, prev, new) != prev)
                goto again;

        local64_add(new - prev, &event->count);
}

static void i915_pmu_enable(struct perf_event *event)
{
        struct drm_i915_private *i915 =
                container_of(event->pmu, typeof(*i915), pmu.base);
        unsigned int bit = event_enabled_bit(event);
        unsigned long flags;

        spin_lock_irqsave(&i915->pmu.lock, flags);

        /*
         * Update the bitmask of enabled events and increment
         * the event reference counter.
         */
        GEM_BUG_ON(bit >= I915_PMU_MASK_BITS);
        GEM_BUG_ON(i915->pmu.enable_count[bit] == ~0);
        i915->pmu.enable |= BIT_ULL(bit);
        i915->pmu.enable_count[bit]++;

        /*
         * Start the sampling timer if needed and not already enabled.
         */
        __i915_pmu_maybe_start_timer(i915);

        /*
         * For per-engine events the bitmask and reference counting
         * is stored per engine.
         */
        if (is_engine_event(event)) {
                u8 sample = engine_event_sample(event);
                struct intel_engine_cs *engine;

                engine = intel_engine_lookup_user(i915,
                                                  engine_event_class(event),
                                                  engine_event_instance(event));
                GEM_BUG_ON(!engine);
                engine->pmu.enable |= BIT(sample);

                GEM_BUG_ON(sample >= I915_PMU_SAMPLE_BITS);
                GEM_BUG_ON(engine->pmu.enable_count[sample] == ~0);
                engine->pmu.enable_count[sample]++;
        }

        spin_unlock_irqrestore(&i915->pmu.lock, flags);

        /*
         * Store the current counter value so we can report the correct delta
         * for all listeners. Even when the event was already enabled and has
         * an existing non-zero value.
         */
        local64_set(&event->hw.prev_count, __i915_pmu_event_read(event));
}

static void i915_pmu_disable(struct perf_event *event)
{
        struct drm_i915_private *i915 =
                container_of(event->pmu, typeof(*i915), pmu.base);
        unsigned int bit = event_enabled_bit(event);
        unsigned long flags;

        spin_lock_irqsave(&i915->pmu.lock, flags);

        if (is_engine_event(event)) {
                u8 sample = engine_event_sample(event);
                struct intel_engine_cs *engine;

                engine = intel_engine_lookup_user(i915,
                                                  engine_event_class(event),
                                                  engine_event_instance(event));
                GEM_BUG_ON(!engine);
                GEM_BUG_ON(sample >= I915_PMU_SAMPLE_BITS);
                GEM_BUG_ON(engine->pmu.enable_count[sample] == 0);
                /*
                 * Decrement the reference count and clear the enabled
                 * bitmask when the last listener on an event goes away.
                 */
                if (--engine->pmu.enable_count[sample] == 0)
                        engine->pmu.enable &= ~BIT(sample);
        }

        GEM_BUG_ON(bit >= I915_PMU_MASK_BITS);
        GEM_BUG_ON(i915->pmu.enable_count[bit] == 0);
        /*
         * Decrement the reference count and clear the enabled
         * bitmask when the last listener on an event goes away.
         */
        if (--i915->pmu.enable_count[bit] == 0) {
                i915->pmu.enable &= ~BIT_ULL(bit);
                i915->pmu.timer_enabled &= pmu_needs_timer(i915, true);
        }

        spin_unlock_irqrestore(&i915->pmu.lock, flags);
}

static void i915_pmu_event_start(struct perf_event *event, int flags)
{
        i915_pmu_enable(event);
        event->hw.state = 0;
}

static void i915_pmu_event_stop(struct perf_event *event, int flags)
{
        if (flags & PERF_EF_UPDATE)
                i915_pmu_event_read(event);
        i915_pmu_disable(event);
        event->hw.state = PERF_HES_STOPPED;
}

static int i915_pmu_event_add(struct perf_event *event, int flags)
{
        if (flags & PERF_EF_START)
                i915_pmu_event_start(event, flags);

        return 0;
}

static void i915_pmu_event_del(struct perf_event *event, int flags)
{
        i915_pmu_event_stop(event, PERF_EF_UPDATE);
}

static int i915_pmu_event_event_idx(struct perf_event *event)
{
        return 0;
}

struct i915_str_attribute {
        struct device_attribute attr;
        const char *str;
};

static ssize_t i915_pmu_format_show(struct device *dev,
                                    struct device_attribute *attr, char *buf)
{
        struct i915_str_attribute *eattr;

        eattr = container_of(attr, struct i915_str_attribute, attr);
        return sprintf(buf, "%s\n", eattr->str);
}

#define I915_PMU_FORMAT_ATTR(_name, _config) \
        (&((struct i915_str_attribute[]) { \
                { .attr = __ATTR(_name, 0444, i915_pmu_format_show, NULL), \
                  .str = _config, } \
        })[0].attr.attr)

static struct attribute *i915_pmu_format_attrs[] = {
        I915_PMU_FORMAT_ATTR(i915_eventid, "config:0-20"),
        NULL,
};

static const struct attribute_group i915_pmu_format_attr_group = {
        .name = "format",
        .attrs = i915_pmu_format_attrs,
};

struct i915_ext_attribute {
        struct device_attribute attr;
        unsigned long val;
};

static ssize_t i915_pmu_event_show(struct device *dev,
                                   struct device_attribute *attr, char *buf)
{
        struct i915_ext_attribute *eattr;

        eattr = container_of(attr, struct i915_ext_attribute, attr);
        return sprintf(buf, "config=0x%lx\n", eattr->val);
}

static struct attribute_group i915_pmu_events_attr_group = {
        .name = "events",
        /* Patch in attrs at runtime. */
};

static ssize_t
i915_pmu_get_attr_cpumask(struct device *dev,
                          struct device_attribute *attr,
                          char *buf)
{
        return cpumap_print_to_pagebuf(true, buf, &i915_pmu_cpumask);
}

static DEVICE_ATTR(cpumask, 0444, i915_pmu_get_attr_cpumask, NULL);

static struct attribute *i915_cpumask_attrs[] = {
        &dev_attr_cpumask.attr,
        NULL,
};

static const struct attribute_group i915_pmu_cpumask_attr_group = {
        .attrs = i915_cpumask_attrs,
};

static const struct attribute_group *i915_pmu_attr_groups[] = {
        &i915_pmu_format_attr_group,
        &i915_pmu_events_attr_group,
        &i915_pmu_cpumask_attr_group,
        NULL
};

#define __event(__config, __name, __unit) \
{ \
        .config = (__config), \
        .name = (__name), \
        .unit = (__unit), \
}

#define __engine_event(__sample, __name) \
{ \
        .sample = (__sample), \
        .name = (__name), \
}

static struct i915_ext_attribute *
add_i915_attr(struct i915_ext_attribute *attr, const char *name, u64 config)
{
        sysfs_attr_init(&attr->attr.attr);
        attr->attr.attr.name = name;
        attr->attr.attr.mode = 0444;
        attr->attr.show = i915_pmu_event_show;
        attr->val = config;

        return ++attr;
}

static struct perf_pmu_events_attr *
add_pmu_attr(struct perf_pmu_events_attr *attr, const char *name,
             const char *str)
{
        sysfs_attr_init(&attr->attr.attr);
        attr->attr.attr.name = name;
        attr->attr.attr.mode = 0444;
        attr->attr.show = perf_event_sysfs_show;
        attr->event_str = str;

        return ++attr;
}

static struct attribute **
create_event_attributes(struct drm_i915_private *i915)
{
        static const struct {
                u64 config;
                const char *name;
                const char *unit;
        } events[] = {
                __event(I915_PMU_ACTUAL_FREQUENCY, "actual-frequency", "M"),
                __event(I915_PMU_REQUESTED_FREQUENCY, "requested-frequency", "M"),
                __event(I915_PMU_INTERRUPTS, "interrupts", NULL),
                __event(I915_PMU_RC6_RESIDENCY, "rc6-residency", "ns"),
        };
        static const struct {
                enum drm_i915_pmu_engine_sample sample;
                char *name;
        } engine_events[] = {
                __engine_event(I915_SAMPLE_BUSY, "busy"),
                __engine_event(I915_SAMPLE_SEMA, "sema"),
                __engine_event(I915_SAMPLE_WAIT, "wait"),
        };
        unsigned int count = 0;
        struct perf_pmu_events_attr *pmu_attr = NULL, *pmu_iter;
        struct i915_ext_attribute *i915_attr = NULL, *i915_iter;
        struct attribute **attr = NULL, **attr_iter;
        struct intel_engine_cs *engine;
        enum intel_engine_id id;
        unsigned int i;

        /* Count how many counters we will be exposing. */
        for (i = 0; i < ARRAY_SIZE(events); i++) {
                if (!config_status(i915, events[i].config))
                        count++;
        }

        for_each_engine(engine, i915, id) {
                for (i = 0; i < ARRAY_SIZE(engine_events); i++) {
                        if (!engine_event_status(engine,
                                                 engine_events[i].sample))
                                count++;
                }
        }

        /* Allocate attribute objects and table. */
        i915_attr = kcalloc(count, sizeof(*i915_attr), GFP_KERNEL);
        if (!i915_attr)
                goto err_alloc;

        pmu_attr = kcalloc(count, sizeof(*pmu_attr), GFP_KERNEL);
        if (!pmu_attr)
                goto err_alloc;

        /* Max one pointer of each attribute type plus a termination entry. */
        attr = kcalloc(count * 2 + 1, sizeof(*attr), GFP_KERNEL);
        if (!attr)
                goto err_alloc;

        i915_iter = i915_attr;
        pmu_iter = pmu_attr;
        attr_iter = attr;

        /* Initialize supported non-engine counters. */
        for (i = 0; i < ARRAY_SIZE(events); i++) {
                char *str;

                if (config_status(i915, events[i].config))
                        continue;

                str = kstrdup(events[i].name, GFP_KERNEL);
                if (!str)
                        goto err;

                *attr_iter++ = &i915_iter->attr.attr;
                i915_iter = add_i915_attr(i915_iter, str, events[i].config);

                if (events[i].unit) {
                        str = kasprintf(GFP_KERNEL, "%s.unit", events[i].name);
                        if (!str)
                                goto err;

                        *attr_iter++ = &pmu_iter->attr.attr;
                        pmu_iter = add_pmu_attr(pmu_iter, str, events[i].unit);
                }
        }

        /* Initialize supported engine counters. */
        for_each_engine(engine, i915, id) {
                for (i = 0; i < ARRAY_SIZE(engine_events); i++) {
                        char *str;

                        if (engine_event_status(engine,
                                                engine_events[i].sample))
                                continue;

                        str = kasprintf(GFP_KERNEL, "%s-%s",
                                        engine->name, engine_events[i].name);
                        if (!str)
                                goto err;

                        *attr_iter++ = &i915_iter->attr.attr;
                        i915_iter =
                                add_i915_attr(i915_iter, str,
                                              __I915_PMU_ENGINE(engine->uabi_class,
                                                                engine->instance,
                                                                engine_events[i].sample));

                        str = kasprintf(GFP_KERNEL, "%s-%s.unit",
                                        engine->name, engine_events[i].name);
                        if (!str)
                                goto err;

                        *attr_iter++ = &pmu_iter->attr.attr;
                        pmu_iter = add_pmu_attr(pmu_iter, str, "ns");
                }
        }

        i915->pmu.i915_attr = i915_attr;
        i915->pmu.pmu_attr = pmu_attr;

        return attr;

err:;
        for (attr_iter = attr; *attr_iter; attr_iter++)
                kfree((*attr_iter)->name);

err_alloc:
        kfree(attr);
        kfree(i915_attr);
        kfree(pmu_attr);

        return NULL;
}

static void free_event_attributes(struct drm_i915_private *i915)
{
        struct attribute **attr_iter = i915_pmu_events_attr_group.attrs;

        for (; *attr_iter; attr_iter++)
                kfree((*attr_iter)->name);

        kfree(i915_pmu_events_attr_group.attrs);
        kfree(i915->pmu.i915_attr);
        kfree(i915->pmu.pmu_attr);

        i915_pmu_events_attr_group.attrs = NULL;
        i915->pmu.i915_attr = NULL;
        i915->pmu.pmu_attr = NULL;
}

static int i915_pmu_cpu_online(unsigned int cpu, struct hlist_node *node)
{
        struct i915_pmu *pmu = hlist_entry_safe(node, typeof(*pmu), node);

        GEM_BUG_ON(!pmu->base.event_init);

        /* Select the first online CPU as a designated reader. */
        if (!cpumask_weight(&i915_pmu_cpumask))
                cpumask_set_cpu(cpu, &i915_pmu_cpumask);

        return 0;
}

static int i915_pmu_cpu_offline(unsigned int cpu, struct hlist_node *node)
{
        struct i915_pmu *pmu = hlist_entry_safe(node, typeof(*pmu), node);
        unsigned int target;

        GEM_BUG_ON(!pmu->base.event_init);

        if (cpumask_test_and_clear_cpu(cpu, &i915_pmu_cpumask)) {
                target = cpumask_any_but(topology_sibling_cpumask(cpu), cpu);
                /* Migrate events if there is a valid target */
                if (target < nr_cpu_ids) {
                        cpumask_set_cpu(target, &i915_pmu_cpumask);
                        perf_pmu_migrate_context(&pmu->base, cpu, target);
                }
        }

        return 0;
}

static enum cpuhp_state cpuhp_slot = CPUHP_INVALID;

static int i915_pmu_register_cpuhp_state(struct drm_i915_private *i915)
{
        enum cpuhp_state slot;
        int ret;

        ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
                                      "perf/x86/intel/i915:online",
                                      i915_pmu_cpu_online,
                                      i915_pmu_cpu_offline);
        if (ret < 0)
                return ret;

        slot = ret;
        ret = cpuhp_state_add_instance(slot, &i915->pmu.node);
        if (ret) {
                cpuhp_remove_multi_state(slot);
                return ret;
        }

        cpuhp_slot = slot;
        return 0;
}

static void i915_pmu_unregister_cpuhp_state(struct drm_i915_private *i915)
{
        WARN_ON(cpuhp_slot == CPUHP_INVALID);
        WARN_ON(cpuhp_state_remove_instance(cpuhp_slot, &i915->pmu.node));
        cpuhp_remove_multi_state(cpuhp_slot);
}

void i915_pmu_register(struct drm_i915_private *i915)
{
        int ret;

        if (INTEL_GEN(i915) <= 2) {
                DRM_INFO("PMU not supported for this GPU.");
                return;
        }

        i915_pmu_events_attr_group.attrs = create_event_attributes(i915);
        if (!i915_pmu_events_attr_group.attrs) {
                ret = -ENOMEM;
                goto err;
        }

        i915->pmu.base.attr_groups      = i915_pmu_attr_groups;
        i915->pmu.base.task_ctx_nr      = perf_invalid_context;
        i915->pmu.base.event_init       = i915_pmu_event_init;
        i915->pmu.base.add              = i915_pmu_event_add;
        i915->pmu.base.del              = i915_pmu_event_del;
        i915->pmu.base.start            = i915_pmu_event_start;
        i915->pmu.base.stop             = i915_pmu_event_stop;
        i915->pmu.base.read             = i915_pmu_event_read;
        i915->pmu.base.event_idx        = i915_pmu_event_event_idx;

        spin_lock_init(&i915->pmu.lock);
        hrtimer_init(&i915->pmu.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
        i915->pmu.timer.function = i915_sample;

        ret = perf_pmu_register(&i915->pmu.base, "i915", -1);
        if (ret)
                goto err;

        ret = i915_pmu_register_cpuhp_state(i915);
        if (ret)
                goto err_unreg;

        return;

err_unreg:
        perf_pmu_unregister(&i915->pmu.base);
err:
        i915->pmu.base.event_init = NULL;
        free_event_attributes(i915);
        DRM_NOTE("Failed to register PMU! (err=%d)\n", ret);
}

void i915_pmu_unregister(struct drm_i915_private *i915)
{
        if (!i915->pmu.base.event_init)
                return;

        WARN_ON(i915->pmu.enable);

        hrtimer_cancel(&i915->pmu.timer);

        i915_pmu_unregister_cpuhp_state(i915);

        perf_pmu_unregister(&i915->pmu.base);
        i915->pmu.base.event_init = NULL;
        free_event_attributes(i915);
}