/*
 * Performance events - AMD IBS
 *
 *  Copyright (C) 2011 Advanced Micro Devices, Inc., Robert Richter
 *
 *  For licencing details see kernel-base/COPYING
 */

#include <linux/perf_event.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/pci.h>
#include <linux/ptrace.h>
#include <linux/syscore_ops.h>
#include <linux/sched/clock.h>

#include <asm/apic.h>

#include "../perf_event.h"

static u32 ibs_caps;

#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_AMD)

#include <linux/kprobes.h>
#include <linux/hardirq.h>

#include <asm/nmi.h>

#define IBS_FETCH_CONFIG_MASK   (IBS_FETCH_RAND_EN | IBS_FETCH_MAX_CNT)
#define IBS_OP_CONFIG_MASK      IBS_OP_MAX_CNT


/*
 * IBS states:
 *
 * ENABLED; tracks the pmu::add(), pmu::del() state, when set the counter is taken
 * and any further add()s must fail.
 *
 * STARTED/STOPPING/STOPPED; deal with pmu::start(), pmu::stop() state but are
 * complicated by the fact that the IBS hardware can send late NMIs (ie. after
 * we've cleared the EN bit).
 *
 * In order to consume these late NMIs we have the STOPPED state, any NMI that
 * happens after we've cleared the EN state will clear this bit and report the
 * NMI handled (this is fundamentally racy in the face or multiple NMI sources,
 * someone else can consume our BIT and our NMI will go unhandled).
 *
 * And since we cannot set/clear this separate bit together with the EN bit,
 * there are races; if we cleared STARTED early, an NMI could land in
 * between clearing STARTED and clearing the EN bit (in fact multiple NMIs
 * could happen if the period is small enough), and consume our STOPPED bit
 * and trigger streams of unhandled NMIs.
 *
 * If, however, we clear STARTED late, an NMI can hit between clearing the
 * EN bit and clearing STARTED, still see STARTED set and process the event.
 * If this event will have the VALID bit clear, we bail properly, but this
 * is not a given. With VALID set we can end up calling pmu::stop() again
 * (the throttle logic) and trigger the WARNs in there.
 *
 * So what we do is set STOPPING before clearing EN to avoid the pmu::stop()
 * nesting, and clear STARTED late, so that we have a well defined state over
 * the clearing of the EN bit.
 *
 * XXX: we could probably be using !atomic bitops for all this.
 */

enum ibs_states {
        IBS_ENABLED     = 0,
        IBS_STARTED     = 1,
        IBS_STOPPING    = 2,
        IBS_STOPPED     = 3,

        IBS_MAX_STATES,
};

struct cpu_perf_ibs {
        struct perf_event       *event;
        unsigned long           state[BITS_TO_LONGS(IBS_MAX_STATES)];
};

struct perf_ibs {
        struct pmu                      pmu;
        unsigned int                    msr;
        u64                             config_mask;
        u64                             cnt_mask;
        u64                             enable_mask;
        u64                             valid_mask;
        u64                             max_period;
        unsigned long                   offset_mask[1];
        int                             offset_max;
        struct cpu_perf_ibs __percpu    *pcpu;

        struct attribute                **format_attrs;
        struct attribute_group          format_group;
        const struct attribute_group    *attr_groups[2];

        u64                             (*get_count)(u64 config);
};

struct perf_ibs_data {
        u32             size;
        union {
                u32     data[0];        /* data buffer starts here */
                u32     caps;
        };
        u64             regs[MSR_AMD64_IBS_REG_COUNT_MAX];
};

static int
perf_event_set_period(struct hw_perf_event *hwc, u64 min, u64 max, u64 *hw_period)
{
        s64 left = local64_read(&hwc->period_left);
        s64 period = hwc->sample_period;
        int overflow = 0;

        /*
         * If we are way outside a reasonable range then just skip forward:
         */
        if (unlikely(left <= -period)) {
                left = period;
                local64_set(&hwc->period_left, left);
                hwc->last_period = period;
                overflow = 1;
        }

        if (unlikely(left < (s64)min)) {
                left += period;
                local64_set(&hwc->period_left, left);
                hwc->last_period = period;
                overflow = 1;
        }

        /*
         * If the hw period that triggers the sw overflow is too short
         * we might hit the irq handler. This biases the results.
         * Thus we shorten the next-to-last period and set the last
         * period to the max period.
         */
        if (left > max) {
                left -= max;
                if (left > max)
                        left = max;
                else if (left < min)
                        left = min;
        }

        *hw_period = (u64)left;

        return overflow;
}

static  int
perf_event_try_update(struct perf_event *event, u64 new_raw_count, int width)
{
        struct hw_perf_event *hwc = &event->hw;
        int shift = 64 - width;
        u64 prev_raw_count;
        u64 delta;

        /*
         * Careful: an NMI might modify the previous event value.
         *
         * Our tactic to handle this is to first atomically read and
         * exchange a new raw count - then add that new-prev delta
         * count to the generic event atomically:
         */
        prev_raw_count = local64_read(&hwc->prev_count);
        if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
                                        new_raw_count) != prev_raw_count)
                return 0;

        /*
         * 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.
         *
         * Careful, not all hw sign-extends above the physical width
         * of the count.
         */
        delta = (new_raw_count << shift) - (prev_raw_count << shift);
        delta >>= shift;

        local64_add(delta, &event->count);
        local64_sub(delta, &hwc->period_left);

        return 1;
}

static struct perf_ibs perf_ibs_fetch;
static struct perf_ibs perf_ibs_op;

static struct perf_ibs *get_ibs_pmu(int type)
{
        if (perf_ibs_fetch.pmu.type == type)
                return &perf_ibs_fetch;
        if (perf_ibs_op.pmu.type == type)
                return &perf_ibs_op;
        return NULL;
}

/*
 * Use IBS for precise event sampling:
 *
 *  perf record -a -e cpu-cycles:p ...    # use ibs op counting cycle count
 *  perf record -a -e r076:p ...          # same as -e cpu-cycles:p
 *  perf record -a -e r0C1:p ...          # use ibs op counting micro-ops
 *
 * IbsOpCntCtl (bit 19) of IBS Execution Control Register (IbsOpCtl,
 * MSRC001_1033) is used to select either cycle or micro-ops counting
 * mode.
 *
 * The rip of IBS samples has skid 0. Thus, IBS supports precise
 * levels 1 and 2 and the PERF_EFLAGS_EXACT is set. In rare cases the
 * rip is invalid when IBS was not able to record the rip correctly.
 * We clear PERF_EFLAGS_EXACT and take the rip from pt_regs then.
 *
 */
static int perf_ibs_precise_event(struct perf_event *event, u64 *config)
{
        switch (event->attr.precise_ip) {
        case 0:
                return -ENOENT;
        case 1:
        case 2:
                break;
        default:
                return -EOPNOTSUPP;
        }

        switch (event->attr.type) {
        case PERF_TYPE_HARDWARE:
                switch (event->attr.config) {
                case PERF_COUNT_HW_CPU_CYCLES:
                        *config = 0;
                        return 0;
                }
                break;
        case PERF_TYPE_RAW:
                switch (event->attr.config) {
                case 0x0076:
                        *config = 0;
                        return 0;
                case 0x00C1:
                        *config = IBS_OP_CNT_CTL;
                        return 0;
                }
                break;
        default:
                return -ENOENT;
        }

        return -EOPNOTSUPP;
}

static const struct perf_event_attr ibs_notsupp = {
        .exclude_user   = 1,
        .exclude_kernel = 1,
        .exclude_hv     = 1,
        .exclude_idle   = 1,
        .exclude_host   = 1,
        .exclude_guest  = 1,
};

static int perf_ibs_init(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;
        struct perf_ibs *perf_ibs;
        u64 max_cnt, config;
        int ret;

        perf_ibs = get_ibs_pmu(event->attr.type);
        if (perf_ibs) {
                config = event->attr.config;
        } else {
                perf_ibs = &perf_ibs_op;
                ret = perf_ibs_precise_event(event, &config);
                if (ret)
                        return ret;
        }

        if (event->pmu != &perf_ibs->pmu)
                return -ENOENT;

        if (perf_flags(&event->attr) & perf_flags(&ibs_notsupp))
                return -EINVAL;

        if (config & ~perf_ibs->config_mask)
                return -EINVAL;

        if (hwc->sample_period) {
                if (config & perf_ibs->cnt_mask)
                        /* raw max_cnt may not be set */
                        return -EINVAL;
                if (!event->attr.sample_freq && hwc->sample_period & 0x0f)
                        /*
                         * lower 4 bits can not be set in ibs max cnt,
                         * but allowing it in case we adjust the
                         * sample period to set a frequency.
                         */
                        return -EINVAL;
                hwc->sample_period &= ~0x0FULL;
                if (!hwc->sample_period)
                        hwc->sample_period = 0x10;
        } else {
                max_cnt = config & perf_ibs->cnt_mask;
                config &= ~perf_ibs->cnt_mask;
                event->attr.sample_period = max_cnt << 4;
                hwc->sample_period = event->attr.sample_period;
        }

        if (!hwc->sample_period)
                return -EINVAL;

        /*
         * If we modify hwc->sample_period, we also need to update
         * hwc->last_period and hwc->period_left.
         */
        hwc->last_period = hwc->sample_period;
        local64_set(&hwc->period_left, hwc->sample_period);

        hwc->config_base = perf_ibs->msr;
        hwc->config = config;

        return 0;
}

static int perf_ibs_set_period(struct perf_ibs *perf_ibs,
                               struct hw_perf_event *hwc, u64 *period)
{
        int overflow;

        /* ignore lower 4 bits in min count: */
        overflow = perf_event_set_period(hwc, 1<<4, perf_ibs->max_period, period);
        local64_set(&hwc->prev_count, 0);

        return overflow;
}

static u64 get_ibs_fetch_count(u64 config)
{
        return (config & IBS_FETCH_CNT) >> 12;
}

static u64 get_ibs_op_count(u64 config)
{
        u64 count = 0;

        if (config & IBS_OP_VAL)
                count += (config & IBS_OP_MAX_CNT) << 4; /* cnt rolled over */

        if (ibs_caps & IBS_CAPS_RDWROPCNT)
                count += (config & IBS_OP_CUR_CNT) >> 32;

        return count;
}

static void
perf_ibs_event_update(struct perf_ibs *perf_ibs, struct perf_event *event,
                      u64 *config)
{
        u64 count = perf_ibs->get_count(*config);

        /*
         * Set width to 64 since we do not overflow on max width but
         * instead on max count. In perf_ibs_set_period() we clear
         * prev count manually on overflow.
         */
        while (!perf_event_try_update(event, count, 64)) {
                rdmsrl(event->hw.config_base, *config);
                count = perf_ibs->get_count(*config);
        }
}

static inline void perf_ibs_enable_event(struct perf_ibs *perf_ibs,
                                         struct hw_perf_event *hwc, u64 config)
{
        wrmsrl(hwc->config_base, hwc->config | config | perf_ibs->enable_mask);
}

/*
 * Erratum #420 Instruction-Based Sampling Engine May Generate
 * Interrupt that Cannot Be Cleared:
 *
 * Must clear counter mask first, then clear the enable bit. See
 * Revision Guide for AMD Family 10h Processors, Publication #41322.
 */
static inline void perf_ibs_disable_event(struct perf_ibs *perf_ibs,
                                          struct hw_perf_event *hwc, u64 config)
{
        config &= ~perf_ibs->cnt_mask;
        wrmsrl(hwc->config_base, config);
        config &= ~perf_ibs->enable_mask;
        wrmsrl(hwc->config_base, config);
}

/*
 * We cannot restore the ibs pmu state, so we always needs to update
 * the event while stopping it and then reset the state when starting
 * again. Thus, ignoring PERF_EF_RELOAD and PERF_EF_UPDATE flags in
 * perf_ibs_start()/perf_ibs_stop() and instead always do it.
 */
static void perf_ibs_start(struct perf_event *event, int flags)
{
        struct hw_perf_event *hwc = &event->hw;
        struct perf_ibs *perf_ibs = container_of(event->pmu, struct perf_ibs, pmu);
        struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);
        u64 period;

        if (WARN_ON_ONCE(!(hwc->state & PERF_HES_STOPPED)))
                return;

        WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
        hwc->state = 0;

        perf_ibs_set_period(perf_ibs, hwc, &period);
        /*
         * Set STARTED before enabling the hardware, such that a subsequent NMI
         * must observe it.
         */
        set_bit(IBS_STARTED,    pcpu->state);
        clear_bit(IBS_STOPPING, pcpu->state);
        perf_ibs_enable_event(perf_ibs, hwc, period >> 4);

        perf_event_update_userpage(event);
}

static void perf_ibs_stop(struct perf_event *event, int flags)
{
        struct hw_perf_event *hwc = &event->hw;
        struct perf_ibs *perf_ibs = container_of(event->pmu, struct perf_ibs, pmu);
        struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);
        u64 config;
        int stopping;

        if (test_and_set_bit(IBS_STOPPING, pcpu->state))
                return;

        stopping = test_bit(IBS_STARTED, pcpu->state);

        if (!stopping && (hwc->state & PERF_HES_UPTODATE))
                return;

        rdmsrl(hwc->config_base, config);

        if (stopping) {
                /*
                 * Set STOPPED before disabling the hardware, such that it
                 * must be visible to NMIs the moment we clear the EN bit,
                 * at which point we can generate an !VALID sample which
                 * we need to consume.
                 */
                set_bit(IBS_STOPPED, pcpu->state);
                perf_ibs_disable_event(perf_ibs, hwc, config);
                /*
                 * Clear STARTED after disabling the hardware; if it were
                 * cleared before an NMI hitting after the clear but before
                 * clearing the EN bit might think it a spurious NMI and not
                 * handle it.
                 *
                 * Clearing it after, however, creates the problem of the NMI
                 * handler seeing STARTED but not having a valid sample.
                 */
                clear_bit(IBS_STARTED, pcpu->state);
                WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
                hwc->state |= PERF_HES_STOPPED;
        }

        if (hwc->state & PERF_HES_UPTODATE)
                return;

        /*
         * Clear valid bit to not count rollovers on update, rollovers
         * are only updated in the irq handler.
         */
        config &= ~perf_ibs->valid_mask;

        perf_ibs_event_update(perf_ibs, event, &config);
        hwc->state |= PERF_HES_UPTODATE;
}

static int perf_ibs_add(struct perf_event *event, int flags)
{
        struct perf_ibs *perf_ibs = container_of(event->pmu, struct perf_ibs, pmu);
        struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);

        if (test_and_set_bit(IBS_ENABLED, pcpu->state))
                return -ENOSPC;

        event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;

        pcpu->event = event;

        if (flags & PERF_EF_START)
                perf_ibs_start(event, PERF_EF_RELOAD);

        return 0;
}

static void perf_ibs_del(struct perf_event *event, int flags)
{
        struct perf_ibs *perf_ibs = container_of(event->pmu, struct perf_ibs, pmu);
        struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);

        if (!test_and_clear_bit(IBS_ENABLED, pcpu->state))
                return;

        perf_ibs_stop(event, PERF_EF_UPDATE);

        pcpu->event = NULL;

        perf_event_update_userpage(event);
}

static void perf_ibs_read(struct perf_event *event) { }

PMU_FORMAT_ATTR(rand_en,        "config:57");
PMU_FORMAT_ATTR(cnt_ctl,        "config:19");

static struct attribute *ibs_fetch_format_attrs[] = {
        &format_attr_rand_en.attr,
        NULL,
};

static struct attribute *ibs_op_format_attrs[] = {
        NULL,   /* &format_attr_cnt_ctl.attr if IBS_CAPS_OPCNT */
        NULL,
};

static struct perf_ibs perf_ibs_fetch = {
        .pmu = {
                .task_ctx_nr    = perf_invalid_context,

                .event_init     = perf_ibs_init,
                .add            = perf_ibs_add,
                .del            = perf_ibs_del,
                .start          = perf_ibs_start,
                .stop           = perf_ibs_stop,
                .read           = perf_ibs_read,
        },
        .msr                    = MSR_AMD64_IBSFETCHCTL,
        .config_mask            = IBS_FETCH_CONFIG_MASK,
        .cnt_mask               = IBS_FETCH_MAX_CNT,
        .enable_mask            = IBS_FETCH_ENABLE,
        .valid_mask             = IBS_FETCH_VAL,
        .max_period             = IBS_FETCH_MAX_CNT << 4,
        .offset_mask            = { MSR_AMD64_IBSFETCH_REG_MASK },
        .offset_max             = MSR_AMD64_IBSFETCH_REG_COUNT,
        .format_attrs           = ibs_fetch_format_attrs,

        .get_count              = get_ibs_fetch_count,
};

static struct perf_ibs perf_ibs_op = {
        .pmu = {
                .task_ctx_nr    = perf_invalid_context,

                .event_init     = perf_ibs_init,
                .add            = perf_ibs_add,
                .del            = perf_ibs_del,
                .start          = perf_ibs_start,
                .stop           = perf_ibs_stop,
                .read           = perf_ibs_read,
        },
        .msr                    = MSR_AMD64_IBSOPCTL,
        .config_mask            = IBS_OP_CONFIG_MASK,
        .cnt_mask               = IBS_OP_MAX_CNT,
        .enable_mask            = IBS_OP_ENABLE,
        .valid_mask             = IBS_OP_VAL,
        .max_period             = IBS_OP_MAX_CNT << 4,
        .offset_mask            = { MSR_AMD64_IBSOP_REG_MASK },
        .offset_max             = MSR_AMD64_IBSOP_REG_COUNT,
        .format_attrs           = ibs_op_format_attrs,

        .get_count              = get_ibs_op_count,
};

static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
{
        struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);
        struct perf_event *event = pcpu->event;
        struct hw_perf_event *hwc = &event->hw;
        struct perf_sample_data data;
        struct perf_raw_record raw;
        struct pt_regs regs;
        struct perf_ibs_data ibs_data;
        int offset, size, check_rip, offset_max, throttle = 0;
        unsigned int msr;
        u64 *buf, *config, period;

        if (!test_bit(IBS_STARTED, pcpu->state)) {
fail:
                /*
                 * Catch spurious interrupts after stopping IBS: After
                 * disabling IBS there could be still incoming NMIs
                 * with samples that even have the valid bit cleared.
                 * Mark all this NMIs as handled.
                 */
                if (test_and_clear_bit(IBS_STOPPED, pcpu->state))
                        return 1;

                return 0;
        }

        msr = hwc->config_base;
        buf = ibs_data.regs;
        rdmsrl(msr, *buf);
        if (!(*buf++ & perf_ibs->valid_mask))
                goto fail;

        config = &ibs_data.regs[0];
        perf_ibs_event_update(perf_ibs, event, config);
        perf_sample_data_init(&data, 0, hwc->last_period);
        if (!perf_ibs_set_period(perf_ibs, hwc, &period))
                goto out;       /* no sw counter overflow */

        ibs_data.caps = ibs_caps;
        size = 1;
        offset = 1;
        check_rip = (perf_ibs == &perf_ibs_op && (ibs_caps & IBS_CAPS_RIPINVALIDCHK));
        if (event->attr.sample_type & PERF_SAMPLE_RAW)
                offset_max = perf_ibs->offset_max;
        else if (check_rip)
                offset_max = 2;
        else
                offset_max = 1;
        do {
                rdmsrl(msr + offset, *buf++);
                size++;
                offset = find_next_bit(perf_ibs->offset_mask,
                                       perf_ibs->offset_max,
                                       offset + 1);
        } while (offset < offset_max);
        if (event->attr.sample_type & PERF_SAMPLE_RAW) {
                /*
                 * Read IbsBrTarget and IbsOpData4 separately
                 * depending on their availability.
                 * Can't add to offset_max as they are staggered
                 */
                if (ibs_caps & IBS_CAPS_BRNTRGT) {
                        rdmsrl(MSR_AMD64_IBSBRTARGET, *buf++);
                        size++;
                }
                if (ibs_caps & IBS_CAPS_OPDATA4) {
                        rdmsrl(MSR_AMD64_IBSOPDATA4, *buf++);
                        size++;
                }
        }
        ibs_data.size = sizeof(u64) * size;

        regs = *iregs;
        if (check_rip && (ibs_data.regs[2] & IBS_RIP_INVALID)) {
                regs.flags &= ~PERF_EFLAGS_EXACT;
        } else {
                set_linear_ip(&regs, ibs_data.regs[1]);
                regs.flags |= PERF_EFLAGS_EXACT;
        }

        if (event->attr.sample_type & PERF_SAMPLE_RAW) {
                raw = (struct perf_raw_record){
                        .frag = {
                                .size = sizeof(u32) + ibs_data.size,
                                .data = ibs_data.data,
                        },
                };
                data.raw = &raw;
        }

        throttle = perf_event_overflow(event, &data, &regs);
out:
        if (throttle)
                perf_ibs_stop(event, 0);
        else
                perf_ibs_enable_event(perf_ibs, hwc, period >> 4);

        perf_event_update_userpage(event);

        return 1;
}

static int
perf_ibs_nmi_handler(unsigned int cmd, struct pt_regs *regs)
{
        u64 stamp = sched_clock();
        int handled = 0;

        handled += perf_ibs_handle_irq(&perf_ibs_fetch, regs);
        handled += perf_ibs_handle_irq(&perf_ibs_op, regs);

        if (handled)
                inc_irq_stat(apic_perf_irqs);

        perf_sample_event_took(sched_clock() - stamp);

        return handled;
}
NOKPROBE_SYMBOL(perf_ibs_nmi_handler);

static __init int perf_ibs_pmu_init(struct perf_ibs *perf_ibs, char *name)
{
        struct cpu_perf_ibs __percpu *pcpu;
        int ret;

        pcpu = alloc_percpu(struct cpu_perf_ibs);
        if (!pcpu)
                return -ENOMEM;

        perf_ibs->pcpu = pcpu;

        /* register attributes */
        if (perf_ibs->format_attrs[0]) {
                memset(&perf_ibs->format_group, 0, sizeof(perf_ibs->format_group));
                perf_ibs->format_group.name     = "format";
                perf_ibs->format_group.attrs    = perf_ibs->format_attrs;

                memset(&perf_ibs->attr_groups, 0, sizeof(perf_ibs->attr_groups));
                perf_ibs->attr_groups[0]        = &perf_ibs->format_group;
                perf_ibs->pmu.attr_groups       = perf_ibs->attr_groups;
        }

        ret = perf_pmu_register(&perf_ibs->pmu, name, -1);
        if (ret) {
                perf_ibs->pcpu = NULL;
                free_percpu(pcpu);
        }

        return ret;
}

static __init void perf_event_ibs_init(void)
{
        struct attribute **attr = ibs_op_format_attrs;

        perf_ibs_pmu_init(&perf_ibs_fetch, "ibs_fetch");

        if (ibs_caps & IBS_CAPS_OPCNT) {
                perf_ibs_op.config_mask |= IBS_OP_CNT_CTL;
                *attr++ = &format_attr_cnt_ctl.attr;
        }
        perf_ibs_pmu_init(&perf_ibs_op, "ibs_op");

        register_nmi_handler(NMI_LOCAL, perf_ibs_nmi_handler, 0, "perf_ibs");
        pr_info("perf: AMD IBS detected (0x%08x)\n", ibs_caps);
}

#else /* defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_AMD) */

static __init void perf_event_ibs_init(void) { }

#endif

/* IBS - apic initialization, for perf and oprofile */

static __init u32 __get_ibs_caps(void)
{
        u32 caps;
        unsigned int max_level;

        if (!boot_cpu_has(X86_FEATURE_IBS))
                return 0;

        /* check IBS cpuid feature flags */
        max_level = cpuid_eax(0x80000000);
        if (max_level < IBS_CPUID_FEATURES)
                return IBS_CAPS_DEFAULT;

        caps = cpuid_eax(IBS_CPUID_FEATURES);
        if (!(caps & IBS_CAPS_AVAIL))
                /* cpuid flags not valid */
                return IBS_CAPS_DEFAULT;

        return caps;
}

u32 get_ibs_caps(void)
{
        return ibs_caps;
}

EXPORT_SYMBOL(get_ibs_caps);

static inline int get_eilvt(int offset)
{
        return !setup_APIC_eilvt(offset, 0, APIC_EILVT_MSG_NMI, 1);
}

static inline int put_eilvt(int offset)
{
        return !setup_APIC_eilvt(offset, 0, 0, 1);
}

/*
 * Check and reserve APIC extended interrupt LVT offset for IBS if available.
 */
static inline int ibs_eilvt_valid(void)
{
        int offset;
        u64 val;
        int valid = 0;

        preempt_disable();

        rdmsrl(MSR_AMD64_IBSCTL, val);
        offset = val & IBSCTL_LVT_OFFSET_MASK;

        if (!(val & IBSCTL_LVT_OFFSET_VALID)) {
                pr_err(FW_BUG "cpu %d, invalid IBS interrupt offset %d (MSR%08X=0x%016llx)\n",
                       smp_processor_id(), offset, MSR_AMD64_IBSCTL, val);
                goto out;
        }

        if (!get_eilvt(offset)) {
                pr_err(FW_BUG "cpu %d, IBS interrupt offset %d not available (MSR%08X=0x%016llx)\n",
                       smp_processor_id(), offset, MSR_AMD64_IBSCTL, val);
                goto out;
        }

        valid = 1;
out:
        preempt_enable();

        return valid;
}

static int setup_ibs_ctl(int ibs_eilvt_off)
{
        struct pci_dev *cpu_cfg;
        int nodes;
        u32 value = 0;

        nodes = 0;
        cpu_cfg = NULL;
        do {
                cpu_cfg = pci_get_device(PCI_VENDOR_ID_AMD,
                                         PCI_DEVICE_ID_AMD_10H_NB_MISC,
                                         cpu_cfg);
                if (!cpu_cfg)
                        break;
                ++nodes;
                pci_write_config_dword(cpu_cfg, IBSCTL, ibs_eilvt_off
                                       | IBSCTL_LVT_OFFSET_VALID);
                pci_read_config_dword(cpu_cfg, IBSCTL, &value);
                if (value != (ibs_eilvt_off | IBSCTL_LVT_OFFSET_VALID)) {
                        pci_dev_put(cpu_cfg);
                        pr_debug("Failed to setup IBS LVT offset, IBSCTL = 0x%08x\n",
                                 value);
                        return -EINVAL;
                }
        } while (1);

        if (!nodes) {
                pr_debug("No CPU node configured for IBS\n");
                return -ENODEV;
        }

        return 0;
}

/*
 * This runs only on the current cpu. We try to find an LVT offset and
 * setup the local APIC. For this we must disable preemption. On
 * success we initialize all nodes with this offset. This updates then
 * the offset in the IBS_CTL per-node msr. The per-core APIC setup of
 * the IBS interrupt vector is handled by perf_ibs_cpu_notifier that
 * is using the new offset.
 */
static void force_ibs_eilvt_setup(void)
{
        int offset;
        int ret;

        preempt_disable();
        /* find the next free available EILVT entry, skip offset 0 */
        for (offset = 1; offset < APIC_EILVT_NR_MAX; offset++) {
                if (get_eilvt(offset))
                        break;
        }
        preempt_enable();

        if (offset == APIC_EILVT_NR_MAX) {
                pr_debug("No EILVT entry available\n");
                return;
        }

        ret = setup_ibs_ctl(offset);
        if (ret)
                goto out;

        if (!ibs_eilvt_valid())
                goto out;

        pr_info("IBS: LVT offset %d assigned\n", offset);

        return;
out:
        preempt_disable();
        put_eilvt(offset);
        preempt_enable();
        return;
}

static void ibs_eilvt_setup(void)
{
        /*
         * Force LVT offset assignment for family 10h: The offsets are
         * not assigned by the BIOS for this family, so the OS is
         * responsible for doing it. If the OS assignment fails, fall
         * back to BIOS settings and try to setup this.
         */
        if (boot_cpu_data.x86 == 0x10)
                force_ibs_eilvt_setup();
}

static inline int get_ibs_lvt_offset(void)
{
        u64 val;

        rdmsrl(MSR_AMD64_IBSCTL, val);
        if (!(val & IBSCTL_LVT_OFFSET_VALID))
                return -EINVAL;

        return val & IBSCTL_LVT_OFFSET_MASK;
}

static void setup_APIC_ibs(void)
{
        int offset;

        offset = get_ibs_lvt_offset();
        if (offset < 0)
                goto failed;

        if (!setup_APIC_eilvt(offset, 0, APIC_EILVT_MSG_NMI, 0))
                return;
failed:
        pr_warn("perf: IBS APIC setup failed on cpu #%d\n",
                smp_processor_id());
}

static void clear_APIC_ibs(void)
{
        int offset;

        offset = get_ibs_lvt_offset();
        if (offset >= 0)
                setup_APIC_eilvt(offset, 0, APIC_EILVT_MSG_FIX, 1);
}

static int x86_pmu_amd_ibs_starting_cpu(unsigned int cpu)
{
        setup_APIC_ibs();
        return 0;
}

#ifdef CONFIG_PM

static int perf_ibs_suspend(void)
{
        clear_APIC_ibs();
        return 0;
}

static void perf_ibs_resume(void)
{
        ibs_eilvt_setup();
        setup_APIC_ibs();
}

static struct syscore_ops perf_ibs_syscore_ops = {
        .resume         = perf_ibs_resume,
        .suspend        = perf_ibs_suspend,
};

static void perf_ibs_pm_init(void)
{
        register_syscore_ops(&perf_ibs_syscore_ops);
}

#else

static inline void perf_ibs_pm_init(void) { }

#endif

static int x86_pmu_amd_ibs_dying_cpu(unsigned int cpu)
{
        clear_APIC_ibs();
        return 0;
}

static __init int amd_ibs_init(void)
{
        u32 caps;

        caps = __get_ibs_caps();
        if (!caps)
                return -ENODEV; /* ibs not supported by the cpu */

        ibs_eilvt_setup();

        if (!ibs_eilvt_valid())
                return -EINVAL;

        perf_ibs_pm_init();

        ibs_caps = caps;
        /* make ibs_caps visible to other cpus: */
        smp_mb();
        /*
         * x86_pmu_amd_ibs_starting_cpu will be called from core on
         * all online cpus.
         */
        cpuhp_setup_state(CPUHP_AP_PERF_X86_AMD_IBS_STARTING,
                          "perf/x86/amd/ibs:starting",
                          x86_pmu_amd_ibs_starting_cpu,
                          x86_pmu_amd_ibs_dying_cpu);

        perf_event_ibs_init();

        return 0;
}

/* Since we need the pci subsystem to init ibs we can't do this earlier: */
device_initcall(amd_ibs_init);