1 files changed, 690 insertions, 0 deletions

diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
new file mode 100644
index 000000000000..8481ecf2ad71
--- /dev/null
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -0,0 +1,690 @@
+/*
+ * Performance event support for s390x - CPU-measurement Counter Facility
+ *
+ *  Copyright IBM Corp. 2012
+ *  Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ */
+#define KMSG_COMPONENT  "cpum_cf"
+#define pr_fmt(fmt)     KMSG_COMPONENT ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/kernel_stat.h>
+#include <linux/perf_event.h>
+#include <linux/percpu.h>
+#include <linux/notifier.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <asm/system.h>
+#include <asm/irq.h>
+#include <asm/cpu_mf.h>
+
+/* CPU-measurement counter facility supports these CPU counter sets:
+ * For CPU counter sets:
+ *    Basic counter set:             0-31
+ *    Problem-state counter set:    32-63
+ *    Crypto-activity counter set:  64-127
+ *    Extented counter set:        128-159
+ */
+enum cpumf_ctr_set {
+        /* CPU counter sets */
+        CPUMF_CTR_SET_BASIC   = 0,
+        CPUMF_CTR_SET_USER    = 1,
+        CPUMF_CTR_SET_CRYPTO  = 2,
+        CPUMF_CTR_SET_EXT     = 3,
+
+        /* Maximum number of counter sets */
+        CPUMF_CTR_SET_MAX,
+};
+
+#define CPUMF_LCCTL_ENABLE_SHIFT    16
+#define CPUMF_LCCTL_ACTCTL_SHIFT     0
+static const u64 cpumf_state_ctl[CPUMF_CTR_SET_MAX] = {
+        [CPUMF_CTR_SET_BASIC]   = 0x02,
+        [CPUMF_CTR_SET_USER]    = 0x04,
+        [CPUMF_CTR_SET_CRYPTO]  = 0x08,
+        [CPUMF_CTR_SET_EXT]     = 0x01,
+};
+
+static void ctr_set_enable(u64 *state, int ctr_set)
+{
+        *state |= cpumf_state_ctl[ctr_set] << CPUMF_LCCTL_ENABLE_SHIFT;
+}
+static void ctr_set_disable(u64 *state, int ctr_set)
+{
+        *state &= ~(cpumf_state_ctl[ctr_set] << CPUMF_LCCTL_ENABLE_SHIFT);
+}
+static void ctr_set_start(u64 *state, int ctr_set)
+{
+        *state |= cpumf_state_ctl[ctr_set] << CPUMF_LCCTL_ACTCTL_SHIFT;
+}
+static void ctr_set_stop(u64 *state, int ctr_set)
+{
+        *state &= ~(cpumf_state_ctl[ctr_set] << CPUMF_LCCTL_ACTCTL_SHIFT);
+}
+
+/* Local CPUMF event structure */
+struct cpu_hw_events {
+        struct cpumf_ctr_info   info;
+        atomic_t                ctr_set[CPUMF_CTR_SET_MAX];
+        u64                     state, tx_state;
+        unsigned int            flags;
+};
+static DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = {
+        .ctr_set = {
+                [CPUMF_CTR_SET_BASIC]  = ATOMIC_INIT(0),
+                [CPUMF_CTR_SET_USER]   = ATOMIC_INIT(0),
+                [CPUMF_CTR_SET_CRYPTO] = ATOMIC_INIT(0),
+                [CPUMF_CTR_SET_EXT]    = ATOMIC_INIT(0),
+        },
+        .state = 0,
+        .flags = 0,
+};
+
+static int get_counter_set(u64 event)
+{
+        int set = -1;
+
+        if (event < 32)
+                set = CPUMF_CTR_SET_BASIC;
+        else if (event < 64)
+                set = CPUMF_CTR_SET_USER;
+        else if (event < 128)
+                set = CPUMF_CTR_SET_CRYPTO;
+        else if (event < 160)
+                set = CPUMF_CTR_SET_EXT;
+
+        return set;
+}
+
+static int validate_event(const struct hw_perf_event *hwc)
+{
+        switch (hwc->config_base) {
+        case CPUMF_CTR_SET_BASIC:
+        case CPUMF_CTR_SET_USER:
+        case CPUMF_CTR_SET_CRYPTO:
+        case CPUMF_CTR_SET_EXT:
+                /* check for reserved counters */
+                if ((hwc->config >=  6 && hwc->config <=  31) ||
+                    (hwc->config >= 38 && hwc->config <=  63) ||
+                    (hwc->config >= 80 && hwc->config <= 127))
+                        return -EOPNOTSUPP;
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+static int validate_ctr_version(const struct hw_perf_event *hwc)
+{
+        struct cpu_hw_events *cpuhw;
+        int err = 0;
+
+        cpuhw = &get_cpu_var(cpu_hw_events);
+
+        /* check required version for counter sets */
+        switch (hwc->config_base) {
+        case CPUMF_CTR_SET_BASIC:
+        case CPUMF_CTR_SET_USER:
+                if (cpuhw->info.cfvn < 1)
+                        err = -EOPNOTSUPP;
+                break;
+        case CPUMF_CTR_SET_CRYPTO:
+        case CPUMF_CTR_SET_EXT:
+                if (cpuhw->info.csvn < 1)
+                        err = -EOPNOTSUPP;
+                break;
+        }
+
+        put_cpu_var(cpu_hw_events);
+        return err;
+}
+
+static int validate_ctr_auth(const struct hw_perf_event *hwc)
+{
+        struct cpu_hw_events *cpuhw;
+        u64 ctrs_state;
+        int err = 0;
+
+        cpuhw = &get_cpu_var(cpu_hw_events);
+
+        /* check authorization for cpu counter sets */
+        ctrs_state = cpumf_state_ctl[hwc->config_base];
+        if (!(ctrs_state & cpuhw->info.auth_ctl))
+                err = -EPERM;
+
+        put_cpu_var(cpu_hw_events);
+        return err;
+}
+
+/*
+ * Change the CPUMF state to active.
+ * Enable and activate the CPU-counter sets according
+ * to the per-cpu control state.
+ */
+static void cpumf_pmu_enable(struct pmu *pmu)
+{
+        struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
+        int err;
+
+        if (cpuhw->flags & PMU_F_ENABLED)
+                return;
+
+        err = lcctl(cpuhw->state);
+        if (err) {
+                pr_err("Enabling the performance measuring unit "
+                       "failed with rc=%lx\n", err);
+                return;
+        }
+
+        cpuhw->flags |= PMU_F_ENABLED;
+}
+
+/*
+ * Change the CPUMF state to inactive.
+ * Disable and enable (inactive) the CPU-counter sets according
+ * to the per-cpu control state.
+ */
+static void cpumf_pmu_disable(struct pmu *pmu)
+{
+        struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
+        int err;
+        u64 inactive;
+
+        if (!(cpuhw->flags & PMU_F_ENABLED))
+                return;
+
+        inactive = cpuhw->state & ~((1 << CPUMF_LCCTL_ENABLE_SHIFT) - 1);
+        err = lcctl(inactive);
+        if (err) {
+                pr_err("Disabling the performance measuring unit "
+                       "failed with rc=%lx\n", err);
+                return;
+        }
+
+        cpuhw->flags &= ~PMU_F_ENABLED;
+}
+
+
+/* Number of perf events counting hardware events */
+static atomic_t num_events = ATOMIC_INIT(0);
+/* Used to avoid races in calling reserve/release_cpumf_hardware */
+static DEFINE_MUTEX(pmc_reserve_mutex);
+
+/* CPU-measurement alerts for the counter facility */
+static void cpumf_measurement_alert(struct ext_code ext_code,
+                                    unsigned int alert, unsigned long unused)
+{
+        struct cpu_hw_events *cpuhw;
+
+        if (!(alert & CPU_MF_INT_CF_MASK))
+                return;
+
+        kstat_cpu(smp_processor_id()).irqs[EXTINT_CPM]++;
+        cpuhw = &__get_cpu_var(cpu_hw_events);
+
+        /* Measurement alerts are shared and might happen when the PMU
+         * is not reserved.  Ignore these alerts in this case. */
+        if (!(cpuhw->flags & PMU_F_RESERVED))
+                return;
+
+        /* counter authorization change alert */
+        if (alert & CPU_MF_INT_CF_CACA)
+                qctri(&cpuhw->info);
+
+        /* loss of counter data alert */
+        if (alert & CPU_MF_INT_CF_LCDA)
+                pr_err("CPU[%i] Counter data was lost\n", smp_processor_id());
+}
+
+#define PMC_INIT      0
+#define PMC_RELEASE   1
+static void setup_pmc_cpu(void *flags)
+{
+        struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
+
+        switch (*((int *) flags)) {
+        case PMC_INIT:
+                memset(&cpuhw->info, 0, sizeof(cpuhw->info));
+                qctri(&cpuhw->info);
+                cpuhw->flags |= PMU_F_RESERVED;
+                break;
+
+        case PMC_RELEASE:
+                cpuhw->flags &= ~PMU_F_RESERVED;
+                break;
+        }
+
+        /* Disable CPU counter sets */
+        lcctl(0);
+}
+
+/* Initialize the CPU-measurement facility */
+static int reserve_pmc_hardware(void)
+{
+        int flags = PMC_INIT;
+
+        on_each_cpu(setup_pmc_cpu, &flags, 1);
+        measurement_alert_subclass_register();
+
+        return 0;
+}
+
+/* Release the CPU-measurement facility */
+static void release_pmc_hardware(void)
+{
+        int flags = PMC_RELEASE;
+
+        on_each_cpu(setup_pmc_cpu, &flags, 1);
+        measurement_alert_subclass_unregister();
+}
+
+/* Release the PMU if event is the last perf event */
+static void hw_perf_event_destroy(struct perf_event *event)
+{
+        if (!atomic_add_unless(&num_events, -1, 1)) {
+                mutex_lock(&pmc_reserve_mutex);
+                if (atomic_dec_return(&num_events) == 0)
+                        release_pmc_hardware();
+                mutex_unlock(&pmc_reserve_mutex);
+        }
+}
+
+/* CPUMF <-> perf event mappings for kernel+userspace (basic set) */
+static const int cpumf_generic_events_basic[] = {
+        [PERF_COUNT_HW_CPU_CYCLES]          = 0,
+        [PERF_COUNT_HW_INSTRUCTIONS]        = 1,
+        [PERF_COUNT_HW_CACHE_REFERENCES]    = -1,
+        [PERF_COUNT_HW_CACHE_MISSES]        = -1,
+        [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = -1,
+        [PERF_COUNT_HW_BRANCH_MISSES]       = -1,
+        [PERF_COUNT_HW_BUS_CYCLES]          = -1,
+};
+/* CPUMF <-> perf event mappings for userspace (problem-state set) */
+static const int cpumf_generic_events_user[] = {
+        [PERF_COUNT_HW_CPU_CYCLES]          = 32,
+        [PERF_COUNT_HW_INSTRUCTIONS]        = 33,
+        [PERF_COUNT_HW_CACHE_REFERENCES]    = -1,
+        [PERF_COUNT_HW_CACHE_MISSES]        = -1,
+        [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = -1,
+        [PERF_COUNT_HW_BRANCH_MISSES]       = -1,
+        [PERF_COUNT_HW_BUS_CYCLES]          = -1,
+};
+
+static int __hw_perf_event_init(struct perf_event *event)
+{
+        struct perf_event_attr *attr = &event->attr;
+        struct hw_perf_event *hwc = &event->hw;
+        int err;
+        u64 ev;
+
+        switch (attr->type) {
+        case PERF_TYPE_RAW:
+                /* Raw events are used to access counters directly,
+                 * hence do not permit excludes */
+                if (attr->exclude_kernel || attr->exclude_user ||
+                    attr->exclude_hv)
+                        return -EOPNOTSUPP;
+                ev = attr->config;
+                break;
+
+        case PERF_TYPE_HARDWARE:
+                ev = attr->config;
+                /* Count user space (problem-state) only */
+                if (!attr->exclude_user && attr->exclude_kernel) {
+                        if (ev >= ARRAY_SIZE(cpumf_generic_events_user))
+                                return -EOPNOTSUPP;
+                        ev = cpumf_generic_events_user[ev];
+
+                /* No support for kernel space counters only */
+                } else if (!attr->exclude_kernel && attr->exclude_user) {
+                        return -EOPNOTSUPP;
+
+                /* Count user and kernel space */
+                } else {
+                        if (ev >= ARRAY_SIZE(cpumf_generic_events_basic))
+                                return -EOPNOTSUPP;
+                        ev = cpumf_generic_events_basic[ev];
+                }
+                break;
+
+        default:
+                return -ENOENT;
+        }
+
+        if (ev == -1)
+                return -ENOENT;
+
+        if (ev >= PERF_CPUM_CF_MAX_CTR)
+                return -EINVAL;
+
+        /* The CPU measurement counter facility does not have any interrupts
+         * to do sampling.  Sampling must be provided by external means,
+         * for example, by timers.
+         */
+        if (hwc->sample_period)
+                return -EINVAL;
+
+        /* Use the hardware perf event structure to store the counter number
+         * in 'config' member and the counter set to which the counter belongs
+         * in the 'config_base'.  The counter set (config_base) is then used
+         * to enable/disable the counters.
+         */
+        hwc->config = ev;
+        hwc->config_base = get_counter_set(ev);
+
+        /* Validate the counter that is assigned to this event.
+         * Because the counter facility can use numerous counters at the
+         * same time without constraints, it is not necessary to explicity
+         * validate event groups (event->group_leader != event).
+         */
+        err = validate_event(hwc);
+        if (err)
+                return err;
+
+        /* Initialize for using the CPU-measurement counter facility */
+        if (!atomic_inc_not_zero(&num_events)) {
+                mutex_lock(&pmc_reserve_mutex);
+                if (atomic_read(&num_events) == 0 && reserve_pmc_hardware())
+                        err = -EBUSY;
+                else
+                        atomic_inc(&num_events);
+                mutex_unlock(&pmc_reserve_mutex);
+        }
+        event->destroy = hw_perf_event_destroy;
+
+        /* Finally, validate version and authorization of the counter set */
+        err = validate_ctr_auth(hwc);
+        if (!err)
+                err = validate_ctr_version(hwc);
+
+        return err;
+}
+
+static int cpumf_pmu_event_init(struct perf_event *event)
+{
+        int err;
+
+        switch (event->attr.type) {
+        case PERF_TYPE_HARDWARE:
+        case PERF_TYPE_HW_CACHE:
+        case PERF_TYPE_RAW:
+                err = __hw_perf_event_init(event);
+                break;
+        default:
+                return -ENOENT;
+        }
+
+        if (unlikely(err) && event->destroy)
+                event->destroy(event);
+
+        return err;
+}
+
+static int hw_perf_event_reset(struct perf_event *event)
+{
+        u64 prev, new;
+        int err;
+
+        do {
+                prev = local64_read(&event->hw.prev_count);
+                err = ecctr(event->hw.config, &new);
+                if (err) {
+                        if (err != 3)
+                                break;
+                        /* The counter is not (yet) available. This
+                         * might happen if the counter set to which
+                         * this counter belongs is in the disabled
+                         * state.
+                         */
+                        new = 0;
+                }
+        } while (local64_cmpxchg(&event->hw.prev_count, prev, new) != prev);
+
+        return err;
+}
+
+static int hw_perf_event_update(struct perf_event *event)
+{
+        u64 prev, new, delta;
+        int err;
+
+        do {
+                prev = local64_read(&event->hw.prev_count);
+                err = ecctr(event->hw.config, &new);
+                if (err)
+                        goto out;
+        } while (local64_cmpxchg(&event->hw.prev_count, prev, new) != prev);
+
+        delta = (prev <= new) ? new - prev
+                              : (-1ULL - prev) + new + 1;        /* overflow */
+        local64_add(delta, &event->count);
+out:
+        return err;
+}
+
+static void cpumf_pmu_read(struct perf_event *event)
+{
+        if (event->hw.state & PERF_HES_STOPPED)
+                return;
+
+        hw_perf_event_update(event);
+}
+
+static void cpumf_pmu_start(struct perf_event *event, int flags)
+{
+        struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
+        struct hw_perf_event *hwc = &event->hw;
+
+        if (WARN_ON_ONCE(!(hwc->state & PERF_HES_STOPPED)))
+                return;
+
+        if (WARN_ON_ONCE(hwc->config == -1))
+                return;
+
+        if (flags & PERF_EF_RELOAD)
+                WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
+
+        hwc->state = 0;
+
+        /* (Re-)enable and activate the counter set */
+        ctr_set_enable(&cpuhw->state, hwc->config_base);
+        ctr_set_start(&cpuhw->state, hwc->config_base);
+
+        /* The counter set to which this counter belongs can be already active.
+         * Because all counters in a set are active, the event->hw.prev_count
+         * needs to be synchronized.  At this point, the counter set can be in
+         * the inactive or disabled state.
+         */
+        hw_perf_event_reset(event);
+
+        /* increment refcount for this counter set */
+        atomic_inc(&cpuhw->ctr_set[hwc->config_base]);
+}
+
+static void cpumf_pmu_stop(struct perf_event *event, int flags)
+{
+        struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
+        struct hw_perf_event *hwc = &event->hw;
+
+        if (!(hwc->state & PERF_HES_STOPPED)) {
+                /* Decrement reference count for this counter set and if this
+                 * is the last used counter in the set, clear activation
+                 * control and set the counter set state to inactive.
+                 */
+                if (!atomic_dec_return(&cpuhw->ctr_set[hwc->config_base]))
+                        ctr_set_stop(&cpuhw->state, hwc->config_base);
+                event->hw.state |= PERF_HES_STOPPED;
+        }
+
+        if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) {
+                hw_perf_event_update(event);
+                event->hw.state |= PERF_HES_UPTODATE;
+        }
+}
+
+static int cpumf_pmu_add(struct perf_event *event, int flags)
+{
+        struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
+
+        /* Check authorization for the counter set to which this
+         * counter belongs.
+         * For group events transaction, the authorization check is
+         * done in cpumf_pmu_commit_txn().
+         */
+        if (!(cpuhw->flags & PERF_EVENT_TXN))
+                if (validate_ctr_auth(&event->hw))
+                        return -EPERM;
+
+        ctr_set_enable(&cpuhw->state, event->hw.config_base);
+        event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
+
+        if (flags & PERF_EF_START)
+                cpumf_pmu_start(event, PERF_EF_RELOAD);
+
+        perf_event_update_userpage(event);
+
+        return 0;
+}
+
+static void cpumf_pmu_del(struct perf_event *event, int flags)
+{
+        struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
+
+        cpumf_pmu_stop(event, PERF_EF_UPDATE);
+
+        /* Check if any counter in the counter set is still used.  If not used,
+         * change the counter set to the disabled state.  This also clears the
+         * content of all counters in the set.
+         *
+         * When a new perf event has been added but not yet started, this can
+         * clear enable control and resets all counters in a set.  Therefore,
+         * cpumf_pmu_start() always has to reenable a counter set.
+         */
+        if (!atomic_read(&cpuhw->ctr_set[event->hw.config_base]))
+                ctr_set_disable(&cpuhw->state, event->hw.config_base);
+
+        perf_event_update_userpage(event);
+}
+
+/*
+ * Start group events scheduling transaction.
+ * Set flags to perform a single test at commit time.
+ */
+static void cpumf_pmu_start_txn(struct pmu *pmu)
+{
+        struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
+
+        perf_pmu_disable(pmu);
+        cpuhw->flags |= PERF_EVENT_TXN;
+        cpuhw->tx_state = cpuhw->state;
+}
+
+/*
+ * Stop and cancel a group events scheduling tranctions.
+ * Assumes cpumf_pmu_del() is called for each successful added
+ * cpumf_pmu_add() during the transaction.
+ */
+static void cpumf_pmu_cancel_txn(struct pmu *pmu)
+{
+        struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
+
+        WARN_ON(cpuhw->tx_state != cpuhw->state);
+
+        cpuhw->flags &= ~PERF_EVENT_TXN;
+        perf_pmu_enable(pmu);
+}
+
+/*
+ * Commit the group events scheduling transaction.  On success, the
+ * transaction is closed.   On error, the transaction is kept open
+ * until cpumf_pmu_cancel_txn() is called.
+ */
+static int cpumf_pmu_commit_txn(struct pmu *pmu)
+{
+        struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
+        u64 state;
+
+        /* check if the updated state can be scheduled */
+        state = cpuhw->state & ~((1 << CPUMF_LCCTL_ENABLE_SHIFT) - 1);
+        state >>= CPUMF_LCCTL_ENABLE_SHIFT;
+        if ((state & cpuhw->info.auth_ctl) != state)
+                return -EPERM;
+
+        cpuhw->flags &= ~PERF_EVENT_TXN;
+        perf_pmu_enable(pmu);
+        return 0;
+}
+
+/* Performance monitoring unit for s390x */
+static struct pmu cpumf_pmu = {
+        .pmu_enable   = cpumf_pmu_enable,
+        .pmu_disable  = cpumf_pmu_disable,
+        .event_init   = cpumf_pmu_event_init,
+        .add          = cpumf_pmu_add,
+        .del          = cpumf_pmu_del,
+        .start        = cpumf_pmu_start,
+        .stop         = cpumf_pmu_stop,
+        .read         = cpumf_pmu_read,
+        .start_txn    = cpumf_pmu_start_txn,
+        .commit_txn   = cpumf_pmu_commit_txn,
+        .cancel_txn   = cpumf_pmu_cancel_txn,
+};
+
+static int __cpuinit cpumf_pmu_notifier(struct notifier_block *self,
+                                        unsigned long action, void *hcpu)
+{
+        unsigned int cpu = (long) hcpu;
+        int flags;
+
+        switch (action & ~CPU_TASKS_FROZEN) {
+        case CPU_ONLINE:
+                flags = PMC_INIT;
+                smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1);
+                break;
+        case CPU_DOWN_PREPARE:
+                flags = PMC_RELEASE;
+                smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1);
+                break;
+        default:
+                break;
+        }
+
+        return NOTIFY_OK;
+}
+
+static int __init cpumf_pmu_init(void)
+{
+        int rc;
+
+        if (!cpum_cf_avail())
+                return -ENODEV;
+
+        /* clear bit 15 of cr0 to unauthorize problem-state to
+         * extract measurement counters */
+        ctl_clear_bit(0, 48);
+
+        /* register handler for measurement-alert interruptions */
+        rc = register_external_interrupt(0x1407, cpumf_measurement_alert);
+        if (rc) {
+                pr_err("Registering for CPU-measurement alerts "
+                       "failed with rc=%i\n", rc);
+                goto out;
+        }
+
+        rc = perf_pmu_register(&cpumf_pmu, "cpum_cf", PERF_TYPE_RAW);
+        if (rc) {
+                pr_err("Registering the cpum_cf PMU failed with rc=%i\n", rc);
+                unregister_external_interrupt(0x1407, cpumf_measurement_alert);
+                goto out;
+        }
+        perf_cpu_notifier(cpumf_pmu_notifier);
+out:
+        return rc;
+}
+early_initcall(cpumf_pmu_init);