// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2020 Intel Corporation. All rights rsvd. */

#include <linux/sched/task.h>
#include <linux/io-64-nonatomic-lo-hi.h>
#include "idxd.h"
#include "perfmon.h"

static ssize_t cpumask_show(struct device *dev, struct device_attribute *attr,
                            char *buf);

static cpumask_t                perfmon_dsa_cpu_mask;
static bool                     cpuhp_set_up;
static enum cpuhp_state         cpuhp_slot;

/*
 * perf userspace reads this attribute to determine which cpus to open
 * counters on.  It's connected to perfmon_dsa_cpu_mask, which is
 * maintained by the cpu hotplug handlers.
 */
static DEVICE_ATTR_RO(cpumask);

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

static struct attribute_group cpumask_attr_group = {
        .attrs = perfmon_cpumask_attrs,
};

/*
 * These attributes specify the bits in the config word that the perf
 * syscall uses to pass the event ids and categories to perfmon.
 */
DEFINE_PERFMON_FORMAT_ATTR(event_category, "config:0-3");
DEFINE_PERFMON_FORMAT_ATTR(event, "config:4-31");

/*
 * These attributes specify the bits in the config1 word that the perf
 * syscall uses to pass filter data to perfmon.
 */
DEFINE_PERFMON_FORMAT_ATTR(filter_wq, "config1:0-31");
DEFINE_PERFMON_FORMAT_ATTR(filter_tc, "config1:32-39");
DEFINE_PERFMON_FORMAT_ATTR(filter_pgsz, "config1:40-43");
DEFINE_PERFMON_FORMAT_ATTR(filter_sz, "config1:44-51");
DEFINE_PERFMON_FORMAT_ATTR(filter_eng, "config1:52-59");

#define PERFMON_FILTERS_START   2
#define PERFMON_FILTERS_MAX     5

static struct attribute *perfmon_format_attrs[] = {
        &format_attr_idxd_event_category.attr,
        &format_attr_idxd_event.attr,
        &format_attr_idxd_filter_wq.attr,
        &format_attr_idxd_filter_tc.attr,
        &format_attr_idxd_filter_pgsz.attr,
        &format_attr_idxd_filter_sz.attr,
        &format_attr_idxd_filter_eng.attr,
        NULL,
};

static struct attribute_group perfmon_format_attr_group = {
        .name = "format",
        .attrs = perfmon_format_attrs,
};

static const struct attribute_group *perfmon_attr_groups[] = {
        &perfmon_format_attr_group,
        &cpumask_attr_group,
        NULL,
};

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

static bool is_idxd_event(struct idxd_pmu *idxd_pmu, struct perf_event *event)
{
        return &idxd_pmu->pmu == event->pmu;
}

static int perfmon_collect_events(struct idxd_pmu *idxd_pmu,
                                  struct perf_event *leader,
                                  bool do_grp)
{
        struct perf_event *event;
        int n, max_count;

        max_count = idxd_pmu->n_counters;
        n = idxd_pmu->n_events;

        if (n >= max_count)
                return -EINVAL;

        if (is_idxd_event(idxd_pmu, leader)) {
                idxd_pmu->event_list[n] = leader;
                idxd_pmu->event_list[n]->hw.idx = n;
                n++;
        }

        if (!do_grp)
                return n;

        for_each_sibling_event(event, leader) {
                if (!is_idxd_event(idxd_pmu, event) ||
                    event->state <= PERF_EVENT_STATE_OFF)
                        continue;

                if (n >= max_count)
                        return -EINVAL;

                idxd_pmu->event_list[n] = event;
                idxd_pmu->event_list[n]->hw.idx = n;
                n++;
        }

        return n;
}

static void perfmon_assign_hw_event(struct idxd_pmu *idxd_pmu,
                                    struct perf_event *event, int idx)
{
        struct idxd_device *idxd = idxd_pmu->idxd;
        struct hw_perf_event *hwc = &event->hw;

        hwc->idx = idx;
        hwc->config_base = ioread64(CNTRCFG_REG(idxd, idx));
        hwc->event_base = ioread64(CNTRCFG_REG(idxd, idx));
}

static int perfmon_assign_event(struct idxd_pmu *idxd_pmu,
                                struct perf_event *event)
{
        int i;

        for (i = 0; i < IDXD_PMU_EVENT_MAX; i++)
                if (!test_and_set_bit(i, idxd_pmu->used_mask))
                        return i;

        return -EINVAL;
}

/*
 * Check whether there are enough counters to satisfy that all the
 * events in the group can actually be scheduled at the same time.
 *
 * To do this, create a fake idxd_pmu object so the event collection
 * and assignment functions can be used without affecting the internal
 * state of the real idxd_pmu object.
 */
static int perfmon_validate_group(struct idxd_pmu *pmu,
                                  struct perf_event *event)
{
        struct perf_event *leader = event->group_leader;
        struct idxd_pmu *fake_pmu;
        int i, ret = 0, n, idx;

        fake_pmu = kzalloc(sizeof(*fake_pmu), GFP_KERNEL);
        if (!fake_pmu)
                return -ENOMEM;

        fake_pmu->pmu.name = pmu->pmu.name;
        fake_pmu->n_counters = pmu->n_counters;

        n = perfmon_collect_events(fake_pmu, leader, true);
        if (n < 0) {
                ret = n;
                goto out;
        }

        fake_pmu->n_events = n;
        n = perfmon_collect_events(fake_pmu, event, false);
        if (n < 0) {
                ret = n;
                goto out;
        }

        fake_pmu->n_events = n;

        for (i = 0; i < n; i++) {
                event = fake_pmu->event_list[i];

                idx = perfmon_assign_event(fake_pmu, event);
                if (idx < 0) {
                        ret = idx;
                        goto out;
                }
        }
out:
        kfree(fake_pmu);

        return ret;
}

static int perfmon_pmu_event_init(struct perf_event *event)
{
        struct idxd_device *idxd;
        int ret = 0;

        idxd = event_to_idxd(event);
        event->hw.idx = -1;

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

        /* sampling not supported */
        if (event->attr.sample_period)
                return -EINVAL;

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

        if (event->pmu != &idxd->idxd_pmu->pmu)
                return -EINVAL;

        event->hw.event_base = ioread64(PERFMON_TABLE_OFFSET(idxd));
        event->cpu = idxd->idxd_pmu->cpu;
        event->hw.config = event->attr.config;

        if (event->group_leader != event)
                 /* non-group events have themselves as leader */
                ret = perfmon_validate_group(idxd->idxd_pmu, event);

        return ret;
}

static inline u64 perfmon_pmu_read_counter(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        struct idxd_device *idxd;
        int cntr = hwc->idx;

        idxd = event_to_idxd(event);

        return ioread64(CNTRDATA_REG(idxd, cntr));
}

static void perfmon_pmu_event_update(struct perf_event *event)
{
        struct idxd_device *idxd = event_to_idxd(event);
        u64 prev_raw_count, new_raw_count, delta, p, n;
        int shift = 64 - idxd->idxd_pmu->counter_width;
        struct hw_perf_event *hwc = &event->hw;

        do {
                prev_raw_count = local64_read(&hwc->prev_count);
                new_raw_count = perfmon_pmu_read_counter(event);
        } while (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
                        new_raw_count) != prev_raw_count);

        n = (new_raw_count << shift);
        p = (prev_raw_count << shift);

        delta = ((n - p) >> shift);

        local64_add(delta, &event->count);
}

void perfmon_counter_overflow(struct idxd_device *idxd)
{
        int i, n_counters, max_loop = OVERFLOW_SIZE;
        struct perf_event *event;
        unsigned long ovfstatus;

        n_counters = min(idxd->idxd_pmu->n_counters, OVERFLOW_SIZE);

        ovfstatus = ioread32(OVFSTATUS_REG(idxd));

        /*
         * While updating overflowed counters, other counters behind
         * them could overflow and be missed in a given pass.
         * Normally this could happen at most n_counters times, but in
         * theory a tiny counter width could result in continual
         * overflows and endless looping.  max_loop provides a
         * failsafe in that highly unlikely case.
         */
        while (ovfstatus && max_loop--) {
                /* Figure out which counter(s) overflowed */
                for_each_set_bit(i, &ovfstatus, n_counters) {
                        unsigned long ovfstatus_clear = 0;

                        /* Update event->count for overflowed counter */
                        event = idxd->idxd_pmu->event_list[i];
                        perfmon_pmu_event_update(event);
                        /* Writing 1 to OVFSTATUS bit clears it */
                        set_bit(i, &ovfstatus_clear);
                        iowrite32(ovfstatus_clear, OVFSTATUS_REG(idxd));
                }

                ovfstatus = ioread32(OVFSTATUS_REG(idxd));
        }

        /*
         * Should never happen.  If so, it means a counter(s) looped
         * around twice while this handler was running.
         */
        WARN_ON_ONCE(ovfstatus);
}

static inline void perfmon_reset_config(struct idxd_device *idxd)
{
        iowrite32(CONFIG_RESET, PERFRST_REG(idxd));
        iowrite32(0, OVFSTATUS_REG(idxd));
        iowrite32(0, PERFFRZ_REG(idxd));
}

static inline void perfmon_reset_counters(struct idxd_device *idxd)
{
        iowrite32(CNTR_RESET, PERFRST_REG(idxd));
}

static inline void perfmon_reset(struct idxd_device *idxd)
{
        perfmon_reset_config(idxd);
        perfmon_reset_counters(idxd);
}

static void perfmon_pmu_event_start(struct perf_event *event, int mode)
{
        u32 flt_wq, flt_tc, flt_pg_sz, flt_xfer_sz, flt_eng = 0;
        u64 cntr_cfg, cntrdata, event_enc, event_cat = 0;
        struct hw_perf_event *hwc = &event->hw;
        union filter_cfg flt_cfg;
        union event_cfg event_cfg;
        struct idxd_device *idxd;
        int cntr;

        idxd = event_to_idxd(event);

        event->hw.idx = hwc->idx;
        cntr = hwc->idx;

        /* Obtain event category and event value from user space */
        event_cfg.val = event->attr.config;
        flt_cfg.val = event->attr.config1;
        event_cat = event_cfg.event_cat;
        event_enc = event_cfg.event_enc;

        /* Obtain filter configuration from user space */
        flt_wq = flt_cfg.wq;
        flt_tc = flt_cfg.tc;
        flt_pg_sz = flt_cfg.pg_sz;
        flt_xfer_sz = flt_cfg.xfer_sz;
        flt_eng = flt_cfg.eng;

        if (flt_wq && test_bit(FLT_WQ, &idxd->idxd_pmu->supported_filters))
                iowrite32(flt_wq, FLTCFG_REG(idxd, cntr, FLT_WQ));
        if (flt_tc && test_bit(FLT_TC, &idxd->idxd_pmu->supported_filters))
                iowrite32(flt_tc, FLTCFG_REG(idxd, cntr, FLT_TC));
        if (flt_pg_sz && test_bit(FLT_PG_SZ, &idxd->idxd_pmu->supported_filters))
                iowrite32(flt_pg_sz, FLTCFG_REG(idxd, cntr, FLT_PG_SZ));
        if (flt_xfer_sz && test_bit(FLT_XFER_SZ, &idxd->idxd_pmu->supported_filters))
                iowrite32(flt_xfer_sz, FLTCFG_REG(idxd, cntr, FLT_XFER_SZ));
        if (flt_eng && test_bit(FLT_ENG, &idxd->idxd_pmu->supported_filters))
                iowrite32(flt_eng, FLTCFG_REG(idxd, cntr, FLT_ENG));

        /* Read the start value */
        cntrdata = ioread64(CNTRDATA_REG(idxd, cntr));
        local64_set(&event->hw.prev_count, cntrdata);

        /* Set counter to event/category */
        cntr_cfg = event_cat << CNTRCFG_CATEGORY_SHIFT;
        cntr_cfg |= event_enc << CNTRCFG_EVENT_SHIFT;
        /* Set interrupt on overflow and counter enable bits */
        cntr_cfg |= (CNTRCFG_IRQ_OVERFLOW | CNTRCFG_ENABLE);

        iowrite64(cntr_cfg, CNTRCFG_REG(idxd, cntr));
}

static void perfmon_pmu_event_stop(struct perf_event *event, int mode)
{
        struct hw_perf_event *hwc = &event->hw;
        struct idxd_device *idxd;
        int i, cntr = hwc->idx;
        u64 cntr_cfg;

        idxd = event_to_idxd(event);

        /* remove this event from event list */
        for (i = 0; i < idxd->idxd_pmu->n_events; i++) {
                if (event != idxd->idxd_pmu->event_list[i])
                        continue;

                for (++i; i < idxd->idxd_pmu->n_events; i++)
                        idxd->idxd_pmu->event_list[i - 1] = idxd->idxd_pmu->event_list[i];
                --idxd->idxd_pmu->n_events;
                break;
        }

        cntr_cfg = ioread64(CNTRCFG_REG(idxd, cntr));
        cntr_cfg &= ~CNTRCFG_ENABLE;
        iowrite64(cntr_cfg, CNTRCFG_REG(idxd, cntr));

        if (mode == PERF_EF_UPDATE)
                perfmon_pmu_event_update(event);

        event->hw.idx = -1;
        clear_bit(cntr, idxd->idxd_pmu->used_mask);
}

static void perfmon_pmu_event_del(struct perf_event *event, int mode)
{
        perfmon_pmu_event_stop(event, PERF_EF_UPDATE);
}

static int perfmon_pmu_event_add(struct perf_event *event, int flags)
{
        struct idxd_device *idxd = event_to_idxd(event);
        struct idxd_pmu *idxd_pmu = idxd->idxd_pmu;
        struct hw_perf_event *hwc = &event->hw;
        int idx, n;

        n = perfmon_collect_events(idxd_pmu, event, false);
        if (n < 0)
                return n;

        hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
        if (!(flags & PERF_EF_START))
                hwc->state |= PERF_HES_ARCH;

        idx = perfmon_assign_event(idxd_pmu, event);
        if (idx < 0)
                return idx;

        perfmon_assign_hw_event(idxd_pmu, event, idx);

        if (flags & PERF_EF_START)
                perfmon_pmu_event_start(event, 0);

        idxd_pmu->n_events = n;

        return 0;
}

static void enable_perfmon_pmu(struct idxd_device *idxd)
{
        iowrite32(COUNTER_UNFREEZE, PERFFRZ_REG(idxd));
}

static void disable_perfmon_pmu(struct idxd_device *idxd)
{
        iowrite32(COUNTER_FREEZE, PERFFRZ_REG(idxd));
}

static void perfmon_pmu_enable(struct pmu *pmu)
{
        struct idxd_device *idxd = pmu_to_idxd(pmu);

        enable_perfmon_pmu(idxd);
}

static void perfmon_pmu_disable(struct pmu *pmu)
{
        struct idxd_device *idxd = pmu_to_idxd(pmu);

        disable_perfmon_pmu(idxd);
}

static void skip_filter(int i)
{
        int j;

        for (j = i; j < PERFMON_FILTERS_MAX; j++)
                perfmon_format_attrs[PERFMON_FILTERS_START + j] =
                        perfmon_format_attrs[PERFMON_FILTERS_START + j + 1];
}

static void idxd_pmu_init(struct idxd_pmu *idxd_pmu)
{
        int i;

        for (i = 0 ; i < PERFMON_FILTERS_MAX; i++) {
                if (!test_bit(i, &idxd_pmu->supported_filters))
                        skip_filter(i);
        }

        idxd_pmu->pmu.name              = idxd_pmu->name;
        idxd_pmu->pmu.attr_groups       = perfmon_attr_groups;
        idxd_pmu->pmu.task_ctx_nr       = perf_invalid_context;
        idxd_pmu->pmu.event_init        = perfmon_pmu_event_init;
        idxd_pmu->pmu.pmu_enable        = perfmon_pmu_enable,
        idxd_pmu->pmu.pmu_disable       = perfmon_pmu_disable,
        idxd_pmu->pmu.add               = perfmon_pmu_event_add;
        idxd_pmu->pmu.del               = perfmon_pmu_event_del;
        idxd_pmu->pmu.start             = perfmon_pmu_event_start;
        idxd_pmu->pmu.stop              = perfmon_pmu_event_stop;
        idxd_pmu->pmu.read              = perfmon_pmu_event_update;
        idxd_pmu->pmu.capabilities      = PERF_PMU_CAP_NO_EXCLUDE;
        idxd_pmu->pmu.module            = THIS_MODULE;
}

void perfmon_pmu_remove(struct idxd_device *idxd)
{
        if (!idxd->idxd_pmu)
                return;

        cpuhp_state_remove_instance(cpuhp_slot, &idxd->idxd_pmu->cpuhp_node);
        perf_pmu_unregister(&idxd->idxd_pmu->pmu);
        kfree(idxd->idxd_pmu);
        idxd->idxd_pmu = NULL;
}

static int perf_event_cpu_online(unsigned int cpu, struct hlist_node *node)
{
        struct idxd_pmu *idxd_pmu;

        idxd_pmu = hlist_entry_safe(node, typeof(*idxd_pmu), cpuhp_node);

        /* select the first online CPU as the designated reader */
        if (cpumask_empty(&perfmon_dsa_cpu_mask)) {
                cpumask_set_cpu(cpu, &perfmon_dsa_cpu_mask);
                idxd_pmu->cpu = cpu;
        }

        return 0;
}

static int perf_event_cpu_offline(unsigned int cpu, struct hlist_node *node)
{
        struct idxd_pmu *idxd_pmu;
        unsigned int target;

        idxd_pmu = hlist_entry_safe(node, typeof(*idxd_pmu), cpuhp_node);

        if (!cpumask_test_and_clear_cpu(cpu, &perfmon_dsa_cpu_mask))
                return 0;

        target = cpumask_any_but(cpu_online_mask, cpu);

        /* migrate events if there is a valid target */
        if (target < nr_cpu_ids)
                cpumask_set_cpu(target, &perfmon_dsa_cpu_mask);
        else
                target = -1;

        perf_pmu_migrate_context(&idxd_pmu->pmu, cpu, target);

        return 0;
}

int perfmon_pmu_init(struct idxd_device *idxd)
{
        union idxd_perfcap perfcap;
        struct idxd_pmu *idxd_pmu;
        int rc = -ENODEV;

        /*
         * perfmon module initialization failed, nothing to do
         */
        if (!cpuhp_set_up)
                return -ENODEV;

        /*
         * If perfmon_offset or num_counters is 0, it means perfmon is
         * not supported on this hardware.
         */
        if (idxd->perfmon_offset == 0)
                return -ENODEV;

        idxd_pmu = kzalloc(sizeof(*idxd_pmu), GFP_KERNEL);
        if (!idxd_pmu)
                return -ENOMEM;

        idxd_pmu->idxd = idxd;
        idxd->idxd_pmu = idxd_pmu;

        if (idxd->data->type == IDXD_TYPE_DSA) {
                rc = sprintf(idxd_pmu->name, "dsa%d", idxd->id);
                if (rc < 0)
                        goto free;
        } else if (idxd->data->type == IDXD_TYPE_IAX) {
                rc = sprintf(idxd_pmu->name, "iax%d", idxd->id);
                if (rc < 0)
                        goto free;
        } else {
                goto free;
        }

        perfmon_reset(idxd);

        perfcap.bits = ioread64(PERFCAP_REG(idxd));

        /*
         * If total perf counter is 0, stop further registration.
         * This is necessary in order to support driver running on
         * guest which does not have pmon support.
         */
        if (perfcap.num_perf_counter == 0)
                goto free;

        /* A counter width of 0 means it can't count */
        if (perfcap.counter_width == 0)
                goto free;

        /* Overflow interrupt and counter freeze support must be available */
        if (!perfcap.overflow_interrupt || !perfcap.counter_freeze)
                goto free;

        /* Number of event categories cannot be 0 */
        if (perfcap.num_event_category == 0)
                goto free;

        /*
         * We don't support per-counter capabilities for now.
         */
        if (perfcap.cap_per_counter)
                goto free;

        idxd_pmu->n_event_categories = perfcap.num_event_category;
        idxd_pmu->supported_event_categories = perfcap.global_event_category;
        idxd_pmu->per_counter_caps_supported = perfcap.cap_per_counter;

        /* check filter capability.  If 0, then filters are not supported */
        idxd_pmu->supported_filters = perfcap.filter;
        if (perfcap.filter)
                idxd_pmu->n_filters = hweight8(perfcap.filter);

        /* Store the total number of counters categories, and counter width */
        idxd_pmu->n_counters = perfcap.num_perf_counter;
        idxd_pmu->counter_width = perfcap.counter_width;

        idxd_pmu_init(idxd_pmu);

        rc = perf_pmu_register(&idxd_pmu->pmu, idxd_pmu->name, -1);
        if (rc)
                goto free;

        rc = cpuhp_state_add_instance(cpuhp_slot, &idxd_pmu->cpuhp_node);
        if (rc) {
                perf_pmu_unregister(&idxd->idxd_pmu->pmu);
                goto free;
        }
out:
        return rc;
free:
        kfree(idxd_pmu);
        idxd->idxd_pmu = NULL;

        goto out;
}

void __init perfmon_init(void)
{
        int rc = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
                                         "driver/dma/idxd/perf:online",
                                         perf_event_cpu_online,
                                         perf_event_cpu_offline);
        if (WARN_ON(rc < 0))
                return;

        cpuhp_slot = rc;
        cpuhp_set_up = true;
}

void __exit perfmon_exit(void)
{
        if (cpuhp_set_up)
                cpuhp_remove_multi_state(cpuhp_slot);
}