perf/x86: Add generic Intel uncore PMU support

This patch adds the generic Intel uncore PMU support, including helper
functions that add/delete uncore events, a hrtimer that periodically
polls the counters to avoid overflow and code that places all events
for a particular socket onto a single cpu.

The code design is based on the structure of Sandy Bridge-EP's uncore
subsystem, which consists of a variety of components, each component
contains one or more "boxes".

(Tooling support follows in the next patches.)
Signed-off-by: Zheng Yan <zheng.z.yan@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1339741902-8449-6-git-send-email-zheng.z.yan@intel.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/Makefile

@@ -32,7 +32,9 @@ obj-$(CONFIG_PERF_EVENTS)		+= perf_event.o
 
 ifdef CONFIG_PERF_EVENTS
 obj-$(CONFIG_CPU_SUP_AMD)		+= perf_event_amd.o
-obj-$(CONFIG_CPU_SUP_INTEL)		+= perf_event_p6.o perf_event_p4.o perf_event_intel_lbr.o perf_event_intel_ds.o perf_event_intel.o
+obj-$(CONFIG_CPU_SUP_INTEL)		+= perf_event_p6.o perf_event_p4.o
+obj-$(CONFIG_CPU_SUP_INTEL)		+= perf_event_intel_lbr.o perf_event_intel_ds.o perf_event_intel.o
+obj-$(CONFIG_CPU_SUP_INTEL)		+= perf_event_intel_uncore.o
 endif
 
 obj-$(CONFIG_X86_MCE)			+= mcheck/

arch/x86/kernel/cpu/perf_event_intel_uncore.c

+#include "perf_event_intel_uncore.h"
+
+static struct intel_uncore_type *empty_uncore[] = { NULL, };
+static struct intel_uncore_type **msr_uncores = empty_uncore;
+
+/* mask of cpus that collect uncore events */
+static cpumask_t uncore_cpu_mask;
+
+/* constraint for the fixed counter */
+static struct event_constraint constraint_fixed =
+	EVENT_CONSTRAINT(~0ULL, 1 << UNCORE_PMC_IDX_FIXED, ~0ULL);
+
+static void uncore_assign_hw_event(struct intel_uncore_box *box,
+				struct perf_event *event, int idx)
+{
+	struct hw_perf_event *hwc = &event->hw;
+
+	hwc->idx = idx;
+	hwc->last_tag = ++box->tags[idx];
+
+	if (hwc->idx == UNCORE_PMC_IDX_FIXED) {
+		hwc->event_base = uncore_msr_fixed_ctr(box);
+		hwc->config_base = uncore_msr_fixed_ctl(box);
+		return;
+	}
+
+	hwc->config_base = uncore_msr_event_ctl(box, hwc->idx);
+	hwc->event_base =  uncore_msr_perf_ctr(box, hwc->idx);
+}
+
+static void uncore_perf_event_update(struct intel_uncore_box *box,
+					struct perf_event *event)
+{
+	u64 prev_count, new_count, delta;
+	int shift;
+
+	if (event->hw.idx >= UNCORE_PMC_IDX_FIXED)
+		shift = 64 - uncore_fixed_ctr_bits(box);
+	else
+		shift = 64 - uncore_perf_ctr_bits(box);
+
+	/* the hrtimer might modify the previous event value */
+again:
+	prev_count = local64_read(&event->hw.prev_count);
+	new_count = uncore_read_counter(box, event);
+	if (local64_xchg(&event->hw.prev_count, new_count) != prev_count)
+		goto again;
+
+	delta = (new_count << shift) - (prev_count << shift);
+	delta >>= shift;
+
+	local64_add(delta, &event->count);
+}
+
+/*
+ * The overflow interrupt is unavailable for SandyBridge-EP, is broken
+ * for SandyBridge. So we use hrtimer to periodically poll the counter
+ * to avoid overflow.
+ */
+static enum hrtimer_restart uncore_pmu_hrtimer(struct hrtimer *hrtimer)
+{
+	struct intel_uncore_box *box;
+	unsigned long flags;
+	int bit;
+
+	box = container_of(hrtimer, struct intel_uncore_box, hrtimer);
+	if (!box->n_active || box->cpu != smp_processor_id())
+		return HRTIMER_NORESTART;
+	/*
+	 * disable local interrupt to prevent uncore_pmu_event_start/stop
+	 * to interrupt the update process
+	 */
+	local_irq_save(flags);
+
+	for_each_set_bit(bit, box->active_mask, UNCORE_PMC_IDX_MAX)
+		uncore_perf_event_update(box, box->events[bit]);
+
+	local_irq_restore(flags);
+
+	hrtimer_forward_now(hrtimer, ns_to_ktime(UNCORE_PMU_HRTIMER_INTERVAL));
+	return HRTIMER_RESTART;
+}
+
+static void uncore_pmu_start_hrtimer(struct intel_uncore_box *box)
+{
+	__hrtimer_start_range_ns(&box->hrtimer,
+			ns_to_ktime(UNCORE_PMU_HRTIMER_INTERVAL), 0,
+			HRTIMER_MODE_REL_PINNED, 0);
+}
+
+static void uncore_pmu_cancel_hrtimer(struct intel_uncore_box *box)
+{
+	hrtimer_cancel(&box->hrtimer);
+}
+
+static void uncore_pmu_init_hrtimer(struct intel_uncore_box *box)
+{
+	hrtimer_init(&box->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	box->hrtimer.function = uncore_pmu_hrtimer;
+}
+
+struct intel_uncore_box *uncore_alloc_box(int cpu)
+{
+	struct intel_uncore_box *box;
+
+	box = kmalloc_node(sizeof(*box), GFP_KERNEL | __GFP_ZERO,
+			   cpu_to_node(cpu));
+	if (!box)
+		return NULL;
+
+	uncore_pmu_init_hrtimer(box);
+	atomic_set(&box->refcnt, 1);
+	box->cpu = -1;
+	box->phys_id = -1;
+
+	return box;
+}
+
+static struct intel_uncore_box *
+uncore_pmu_to_box(struct intel_uncore_pmu *pmu, int cpu)
+{
+	return *per_cpu_ptr(pmu->box, cpu);
+}
+
+static struct intel_uncore_pmu *uncore_event_to_pmu(struct perf_event *event)
+{
+	return container_of(event->pmu, struct intel_uncore_pmu, pmu);
+}
+
+static struct intel_uncore_box *uncore_event_to_box(struct perf_event *event)
+{
+	/*
+	 * perf core schedules event on the basis of cpu, uncore events are
+	 * collected by one of the cpus inside a physical package.
+	 */
+	return uncore_pmu_to_box(uncore_event_to_pmu(event),
+				 smp_processor_id());
+}
+
+static int uncore_collect_events(struct intel_uncore_box *box,
+				struct perf_event *leader, bool dogrp)
+{
+	struct perf_event *event;
+	int n, max_count;
+
+	max_count = box->pmu->type->num_counters;
+	if (box->pmu->type->fixed_ctl)
+		max_count++;
+
+	if (box->n_events >= max_count)
+		return -EINVAL;
+
+	n = box->n_events;
+	box->event_list[n] = leader;
+	n++;
+	if (!dogrp)
+		return n;
+
+	list_for_each_entry(event, &leader->sibling_list, group_entry) {
+		if (event->state <= PERF_EVENT_STATE_OFF)
+			continue;
+
+		if (n >= max_count)
+			return -EINVAL;
+
+		box->event_list[n] = event;
+		n++;
+	}
+	return n;
+}
+
+static struct event_constraint *
+uncore_event_constraint(struct intel_uncore_type *type,
+			struct perf_event *event)
+{
+	struct event_constraint *c;
+
+	if (event->hw.config == ~0ULL)
+		return &constraint_fixed;
+
+	if (type->constraints) {
+		for_each_event_constraint(c, type->constraints) {
+			if ((event->hw.config & c->cmask) == c->code)
+				return c;
+		}
+	}
+
+	return &type->unconstrainted;
+}
+
+static int uncore_assign_events(struct intel_uncore_box *box,
+				int assign[], int n)
+{
+	unsigned long used_mask[BITS_TO_LONGS(UNCORE_PMC_IDX_MAX)];
+	struct event_constraint *c, *constraints[UNCORE_PMC_IDX_MAX];
+	int i, ret, wmin, wmax;
+	struct hw_perf_event *hwc;
+
+	bitmap_zero(used_mask, UNCORE_PMC_IDX_MAX);
+
+	for (i = 0, wmin = UNCORE_PMC_IDX_MAX, wmax = 0; i < n; i++) {
+		c = uncore_event_constraint(box->pmu->type,
+				box->event_list[i]);
+		constraints[i] = c;
+		wmin = min(wmin, c->weight);
+		wmax = max(wmax, c->weight);
+	}
+
+	/* fastpath, try to reuse previous register */
+	for (i = 0; i < n; i++) {
+		hwc = &box->event_list[i]->hw;
+		c = constraints[i];
+
+		/* never assigned */
+		if (hwc->idx == -1)
+			break;
+
+		/* constraint still honored */
+		if (!test_bit(hwc->idx, c->idxmsk))
+			break;
+
+		/* not already used */
+		if (test_bit(hwc->idx, used_mask))
+			break;
+
+		__set_bit(hwc->idx, used_mask);
+		assign[i] = hwc->idx;
+	}
+	if (i == n)
+		return 0;
+
+	/* slow path */
+	ret = perf_assign_events(constraints, n, wmin, wmax, assign);
+	return ret ? -EINVAL : 0;
+}
+
+static void uncore_pmu_event_start(struct perf_event *event, int flags)
+{
+	struct intel_uncore_box *box = uncore_event_to_box(event);
+	int idx = event->hw.idx;
+
+	if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
+		return;
+
+	if (WARN_ON_ONCE(idx == -1 || idx >= UNCORE_PMC_IDX_MAX))
+		return;
+
+	event->hw.state = 0;
+	box->events[idx] = event;
+	box->n_active++;
+	__set_bit(idx, box->active_mask);
+
+	local64_set(&event->hw.prev_count, uncore_read_counter(box, event));
+	uncore_enable_event(box, event);
+
+	if (box->n_active == 1) {
+		uncore_enable_box(box);
+		uncore_pmu_start_hrtimer(box);
+	}
+}
+
+static void uncore_pmu_event_stop(struct perf_event *event, int flags)
+{
+	struct intel_uncore_box *box = uncore_event_to_box(event);
+	struct hw_perf_event *hwc = &event->hw;
+
+	if (__test_and_clear_bit(hwc->idx, box->active_mask)) {
+		uncore_disable_event(box, event);
+		box->n_active--;
+		box->events[hwc->idx] = NULL;
+		WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
+		hwc->state |= PERF_HES_STOPPED;
+
+		if (box->n_active == 0) {
+			uncore_disable_box(box);
+			uncore_pmu_cancel_hrtimer(box);
+		}
+	}
+
+	if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) {
+		/*
+		 * Drain the remaining delta count out of a event
+		 * that we are disabling:
+		 */
+		uncore_perf_event_update(box, event);
+		hwc->state |= PERF_HES_UPTODATE;
+	}
+}
+
+static int uncore_pmu_event_add(struct perf_event *event, int flags)
+{
+	struct intel_uncore_box *box = uncore_event_to_box(event);
+	struct hw_perf_event *hwc = &event->hw;
+	int assign[UNCORE_PMC_IDX_MAX];
+	int i, n, ret;
+
+	if (!box)
+		return -ENODEV;
+
+	ret = n = uncore_collect_events(box, event, false);
+	if (ret < 0)
+		return ret;
+
+	hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
+	if (!(flags & PERF_EF_START))
+		hwc->state |= PERF_HES_ARCH;
+
+	ret = uncore_assign_events(box, assign, n);
+	if (ret)
+		return ret;
+
+	/* save events moving to new counters */
+	for (i = 0; i < box->n_events; i++) {
+		event = box->event_list[i];
+		hwc = &event->hw;
+
+		if (hwc->idx == assign[i] &&
+			hwc->last_tag == box->tags[assign[i]])
+			continue;
+		/*
+		 * Ensure we don't accidentally enable a stopped
+		 * counter simply because we rescheduled.
+		 */
+		if (hwc->state & PERF_HES_STOPPED)
+			hwc->state |= PERF_HES_ARCH;
+
+		uncore_pmu_event_stop(event, PERF_EF_UPDATE);
+	}
+
+	/* reprogram moved events into new counters */
+	for (i = 0; i < n; i++) {
+		event = box->event_list[i];
+		hwc = &event->hw;
+
+		if (hwc->idx != assign[i] ||
+			hwc->last_tag != box->tags[assign[i]])
+			uncore_assign_hw_event(box, event, assign[i]);
+		else if (i < box->n_events)
+			continue;
+
+		if (hwc->state & PERF_HES_ARCH)
+			continue;
+
+		uncore_pmu_event_start(event, 0);
+	}
+	box->n_events = n;
+
+	return 0;
+}
+
+static void uncore_pmu_event_del(struct perf_event *event, int flags)
+{
+	struct intel_uncore_box *box = uncore_event_to_box(event);
+	int i;
+
+	uncore_pmu_event_stop(event, PERF_EF_UPDATE);
+
+	for (i = 0; i < box->n_events; i++) {
+		if (event == box->event_list[i]) {
+			while (++i < box->n_events)
+				box->event_list[i - 1] = box->event_list[i];
+
+			--box->n_events;
+			break;
+		}
+	}
+
+	event->hw.idx = -1;
+	event->hw.last_tag = ~0ULL;
+}
+
+static void uncore_pmu_event_read(struct perf_event *event)
+{
+	struct intel_uncore_box *box = uncore_event_to_box(event);
+	uncore_perf_event_update(box, event);
+}
+
+/*
+ * validation ensures the group can be loaded onto the
+ * PMU if it was the only group available.
+ */
+static int uncore_validate_group(struct intel_uncore_pmu *pmu,
+				struct perf_event *event)
+{
+	struct perf_event *leader = event->group_leader;
+	struct intel_uncore_box *fake_box;
+	int assign[UNCORE_PMC_IDX_MAX];
+	int ret = -EINVAL, n;
+
+	fake_box = uncore_alloc_box(smp_processor_id());
+	if (!fake_box)
+		return -ENOMEM;
+
+	fake_box->pmu = pmu;
+	/*
+	 * the event is not yet connected with its
+	 * siblings therefore we must first collect
+	 * existing siblings, then add the new event
+	 * before we can simulate the scheduling
+	 */
+	n = uncore_collect_events(fake_box, leader, true);
+	if (n < 0)
+		goto out;
+
+	fake_box->n_events = n;
+	n = uncore_collect_events(fake_box, event, false);
+	if (n < 0)
+		goto out;
+
+	fake_box->n_events = n;
+
+	ret = uncore_assign_events(fake_box, assign, n);
+out:
+	kfree(fake_box);
+	return ret;
+}
+
+int uncore_pmu_event_init(struct perf_event *event)
+{
+	struct intel_uncore_pmu *pmu;
+	struct intel_uncore_box *box;
+	struct hw_perf_event *hwc = &event->hw;
+	int ret;
+
+	if (event->attr.type != event->pmu->type)
+		return -ENOENT;
+
+	pmu = uncore_event_to_pmu(event);
+	/* no device found for this pmu */
+	if (pmu->func_id < 0)
+		return -ENOENT;
+
+	/*
+	 * Uncore PMU does measure at all privilege level all the time.
+	 * So it doesn't make sense to specify any exclude bits.
+	 */
+	if (event->attr.exclude_user || event->attr.exclude_kernel ||
+			event->attr.exclude_hv || event->attr.exclude_idle)
+		return -EINVAL;
+
+	/* Sampling not supported yet */
+	if (hwc->sample_period)
+		return -EINVAL;
+
+	/*
+	 * Place all uncore events for a particular physical package
+	 * onto a single cpu
+	 */
+	if (event->cpu < 0)
+		return -EINVAL;
+	box = uncore_pmu_to_box(pmu, event->cpu);
+	if (!box || box->cpu < 0)
+		return -EINVAL;
+	event->cpu = box->cpu;
+
+	if (event->attr.config == UNCORE_FIXED_EVENT) {
+		/* no fixed counter */
+		if (!pmu->type->fixed_ctl)
+			return -EINVAL;
+		/*
+		 * if there is only one fixed counter, only the first pmu
+		 * can access the fixed counter
+		 */
+		if (pmu->type->single_fixed && pmu->pmu_idx > 0)
+			return -EINVAL;
+		hwc->config = ~0ULL;
+	} else {
+		hwc->config = event->attr.config & pmu->type->event_mask;
+	}
+
+	event->hw.idx = -1;
+	event->hw.last_tag = ~0ULL;
+
+	if (event->group_leader != event)
+		ret = uncore_validate_group(pmu, event);
+	else
+		ret = 0;
+
+	return ret;
+}
+
+static int __init uncore_pmu_register(struct intel_uncore_pmu *pmu)
+{
+	int ret;
+
+	pmu->pmu = (struct pmu) {
+		.attr_groups	= pmu->type->attr_groups,
+		.task_ctx_nr	= perf_invalid_context,
+		.event_init	= uncore_pmu_event_init,
+		.add		= uncore_pmu_event_add,
+		.del		= uncore_pmu_event_del,
+		.start		= uncore_pmu_event_start,
+		.stop		= uncore_pmu_event_stop,
+		.read		= uncore_pmu_event_read,
+	};
+
+	if (pmu->type->num_boxes == 1) {
+		if (strlen(pmu->type->name) > 0)
+			sprintf(pmu->name, "uncore_%s", pmu->type->name);
+		else
+			sprintf(pmu->name, "uncore");
+	} else {
+		sprintf(pmu->name, "uncore_%s_%d", pmu->type->name,
+			pmu->pmu_idx);
+	}
+
+	ret = perf_pmu_register(&pmu->pmu, pmu->name, -1);
+	return ret;
+}
+
+static void __init uncore_type_exit(struct intel_uncore_type *type)
+{
+	int i;
+
+	for (i = 0; i < type->num_boxes; i++)
+		free_percpu(type->pmus[i].box);
+	kfree(type->pmus);
+	type->pmus = NULL;
+	kfree(type->attr_groups[1]);
+	type->attr_groups[1] = NULL;
+}
+
+static int __init uncore_type_init(struct intel_uncore_type *type)
+{
+	struct intel_uncore_pmu *pmus;
+	struct attribute_group *events_group;
+	struct attribute **attrs;
+	int i, j;
+
+	pmus = kzalloc(sizeof(*pmus) * type->num_boxes, GFP_KERNEL);
+	if (!pmus)
+		return -ENOMEM;
+
+	type->unconstrainted = (struct event_constraint)
+		__EVENT_CONSTRAINT(0, (1ULL << type->num_counters) - 1,
+				0, type->num_counters, 0);
+
+	for (i = 0; i < type->num_boxes; i++) {
+		pmus[i].func_id = -1;
+		pmus[i].pmu_idx = i;
+		pmus[i].type = type;
+		pmus[i].box = alloc_percpu(struct intel_uncore_box *);
+		if (!pmus[i].box)
+			goto fail;
+	}
+
+	if (type->event_descs) {
+		i = 0;
+		while (type->event_descs[i].attr.attr.name)
+			i++;
+
+		events_group = kzalloc(sizeof(struct attribute *) * (i + 1) +
+					sizeof(*events_group), GFP_KERNEL);
+		if (!events_group)
+			goto fail;
+
+		attrs = (struct attribute **)(events_group + 1);
+		events_group->name = "events";
+		events_group->attrs = attrs;
+
+		for (j = 0; j < i; j++)
+			attrs[j] = &type->event_descs[j].attr.attr;
+
+		type->attr_groups[1] = events_group;
+	}
+
+	type->pmus = pmus;
+	return 0;
+fail:
+	uncore_type_exit(type);
+	return -ENOMEM;
+}
+
+static int __init uncore_types_init(struct intel_uncore_type **types)
+{
+	int i, ret;
+
+	for (i = 0; types[i]; i++) {
+		ret = uncore_type_init(types[i]);
+		if (ret)
+			goto fail;
+	}
+	return 0;
+fail:
+	while (--i >= 0)
+		uncore_type_exit(types[i]);
+	return ret;
+}
+
+static void __cpuinit uncore_cpu_dying(int cpu)
+{
+	struct intel_uncore_type *type;
+	struct intel_uncore_pmu *pmu;
+	struct intel_uncore_box *box;
+	int i, j;
+
+	for (i = 0; msr_uncores[i]; i++) {
+		type = msr_uncores[i];
+		for (j = 0; j < type->num_boxes; j++) {
+			pmu = &type->pmus[j];
+			box = *per_cpu_ptr(pmu->box, cpu);
+			*per_cpu_ptr(pmu->box, cpu) = NULL;
+			if (box && atomic_dec_and_test(&box->refcnt))
+				kfree(box);
+		}
+	}
+}
+
+static int __cpuinit uncore_cpu_starting(int cpu)
+{
+	struct intel_uncore_type *type;
+	struct intel_uncore_pmu *pmu;
+	struct intel_uncore_box *box, *exist;
+	int i, j, k, phys_id;
+
+	phys_id = topology_physical_package_id(cpu);
+
+	for (i = 0; msr_uncores[i]; i++) {
+		type = msr_uncores[i];
+		for (j = 0; j < type->num_boxes; j++) {
+			pmu = &type->pmus[j];
+			box = *per_cpu_ptr(pmu->box, cpu);
+			/* called by uncore_cpu_init? */
+			if (box && box->phys_id >= 0) {
+				uncore_box_init(box);
+				continue;
+			}
+
+			for_each_online_cpu(k) {
+				exist = *per_cpu_ptr(pmu->box, k);
+				if (exist && exist->phys_id == phys_id) {
+					atomic_inc(&exist->refcnt);
+					*per_cpu_ptr(pmu->box, cpu) = exist;
+					kfree(box);
+					box = NULL;
+					break;
+				}
+			}
+
+			if (box) {
+				box->phys_id = phys_id;
+				uncore_box_init(box);
+			}
+		}
+	}
+	return 0;
+}
+
+static int __cpuinit uncore_cpu_prepare(int cpu, int phys_id)
+{
+	struct intel_uncore_type *type;
+	struct intel_uncore_pmu *pmu;
+	struct intel_uncore_box *box;
+	int i, j;
+
+	for (i = 0; msr_uncores[i]; i++) {
+		type = msr_uncores[i];
+		for (j = 0; j < type->num_boxes; j++) {
+			pmu = &type->pmus[j];
+			if (pmu->func_id < 0)
+				pmu->func_id = j;
+
+			box = uncore_alloc_box(cpu);
+			if (!box)
+				return -ENOMEM;
+
+			box->pmu = pmu;
+			box->phys_id = phys_id;
+			*per_cpu_ptr(pmu->box, cpu) = box;
+		}
+	}
+	return 0;
+}
+
+static void __cpuinit uncore_change_context(struct intel_uncore_type **uncores,
+					    int old_cpu, int new_cpu)
+{
+	struct intel_uncore_type *type;
+	struct intel_uncore_pmu *pmu;
+	struct intel_uncore_box *box;
+	int i, j;
+
+	for (i = 0; uncores[i]; i++) {
+		type = uncores[i];
+		for (j = 0; j < type->num_boxes; j++) {
+			pmu = &type->pmus[j];
+			if (old_cpu < 0)
+				box = uncore_pmu_to_box(pmu, new_cpu);
+			else
+				box = uncore_pmu_to_box(pmu, old_cpu);
+			if (!box)
+				continue;
+
+			if (old_cpu < 0) {
+				WARN_ON_ONCE(box->cpu != -1);
+				box->cpu = new_cpu;
+				continue;
+			}
+
+			WARN_ON_ONCE(box->cpu != old_cpu);
+			if (new_cpu >= 0) {
+				uncore_pmu_cancel_hrtimer(box);
+				perf_pmu_migrate_context(&pmu->pmu,
+						old_cpu, new_cpu);
+				box->cpu = new_cpu;
+			} else {
+				box->cpu = -1;
+			}
+		}
+	}
+}
+
+static void __cpuinit uncore_event_exit_cpu(int cpu)
+{
+	int i, phys_id, target;
+
+	/* if exiting cpu is used for collecting uncore events */
+	if (!cpumask_test_and_clear_cpu(cpu, &uncore_cpu_mask))
+		return;
+
+	/* find a new cpu to collect uncore events */
+	phys_id = topology_physical_package_id(cpu);
+	target = -1;
+	for_each_online_cpu(i) {
+		if (i == cpu)
+			continue;
+		if (phys_id == topology_physical_package_id(i)) {
+			target = i;
+			break;
+		}
+	}
+
+	/* migrate uncore events to the new cpu */
+	if (target >= 0)
+		cpumask_set_cpu(target, &uncore_cpu_mask);
+
+	uncore_change_context(msr_uncores, cpu, target);
+}
+
+static void __cpuinit uncore_event_init_cpu(int cpu)
+{
+	int i, phys_id;
+
+	phys_id = topology_physical_package_id(cpu);
+	for_each_cpu(i, &uncore_cpu_mask) {
+		if (phys_id == topology_physical_package_id(i))
+			return;
+	}
+
+	cpumask_set_cpu(cpu, &uncore_cpu_mask);
+
+	uncore_change_context(msr_uncores, -1, cpu);
+}
+
+static int __cpuinit uncore_cpu_notifier(struct notifier_block *self,
+					 unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (long)hcpu;
+
+	/* allocate/free data structure for uncore box */
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_UP_PREPARE:
+		uncore_cpu_prepare(cpu, -1);
+		break;
+	case CPU_STARTING:
+		uncore_cpu_starting(cpu);
+		break;
+	case CPU_UP_CANCELED:
+	case CPU_DYING:
+		uncore_cpu_dying(cpu);
+		break;
+	default:
+		break;
+	}
+
+	/* select the cpu that collects uncore events */
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_DOWN_FAILED:
+	case CPU_STARTING:
+		uncore_event_init_cpu(cpu);
+		break;
+	case CPU_DOWN_PREPARE:
+		uncore_event_exit_cpu(cpu);
+		break;
+	default:
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block uncore_cpu_nb __cpuinitdata = {
+	.notifier_call = uncore_cpu_notifier,
+	/*
+	 * to migrate uncore events, our notifier should be executed
+	 * before perf core's notifier.
+	 */
+	.priority = CPU_PRI_PERF + 1,
+};
+
+static void __init uncore_cpu_setup(void *dummy)
+{
+	uncore_cpu_starting(smp_processor_id());
+}
+
+static int __init uncore_cpu_init(void)
+{
+	int ret, cpu;
+
+	switch (boot_cpu_data.x86_model) {
+	default:
+		return 0;
+	}
+
+	ret = uncore_types_init(msr_uncores);
+	if (ret)
+		return ret;
+
+	get_online_cpus();
+
+	for_each_online_cpu(cpu) {
+		int i, phys_id = topology_physical_package_id(cpu);
+
+		for_each_cpu(i, &uncore_cpu_mask) {
+			if (phys_id == topology_physical_package_id(i)) {
+				phys_id = -1;
+				break;
+			}
+		}
+		if (phys_id < 0)
+			continue;
+
+		uncore_cpu_prepare(cpu, phys_id);
+		uncore_event_init_cpu(cpu);
+	}
+	on_each_cpu(uncore_cpu_setup, NULL, 1);
+
+	register_cpu_notifier(&uncore_cpu_nb);
+
+	put_online_cpus();
+
+	return 0;
+}
+
+static int __init uncore_pmus_register(void)
+{
+	struct intel_uncore_pmu *pmu;
+	struct intel_uncore_type *type;
+	int i, j;
+
+	for (i = 0; msr_uncores[i]; i++) {
+		type = msr_uncores[i];
+		for (j = 0; j < type->num_boxes; j++) {
+			pmu = &type->pmus[j];
+			uncore_pmu_register(pmu);
+		}
+	}
+
+	return 0;
+}
+
+static int __init intel_uncore_init(void)
+{
+	int ret;
+
+	if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
+		return -ENODEV;
+
+	ret = uncore_cpu_init();
+	if (ret)
+		goto fail;
+
+	uncore_pmus_register();
+	return 0;
+fail:
+	return ret;
+}
+device_initcall(intel_uncore_init);

arch/x86/kernel/cpu/perf_event_intel_uncore.h

+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/perf_event.h>
+#include "perf_event.h"
+
+#define UNCORE_PMU_NAME_LEN		32
+#define UNCORE_BOX_HASH_SIZE		8
+
+#define UNCORE_PMU_HRTIMER_INTERVAL	(60 * NSEC_PER_SEC)
+
+#define UNCORE_FIXED_EVENT		0xffff
+#define UNCORE_PMC_IDX_MAX_GENERIC	8
+#define UNCORE_PMC_IDX_FIXED		UNCORE_PMC_IDX_MAX_GENERIC
+#define UNCORE_PMC_IDX_MAX		(UNCORE_PMC_IDX_FIXED + 1)
+
+#define UNCORE_EVENT_CONSTRAINT(c, n) EVENT_CONSTRAINT(c, n, 0xff)
+
+struct intel_uncore_ops;
+struct intel_uncore_pmu;
+struct intel_uncore_box;
+struct uncore_event_desc;
+
+struct intel_uncore_type {
+	const char *name;
+	int num_counters;
+	int num_boxes;
+	int perf_ctr_bits;
+	int fixed_ctr_bits;
+	int single_fixed;
+	unsigned perf_ctr;
+	unsigned event_ctl;
+	unsigned event_mask;
+	unsigned fixed_ctr;
+	unsigned fixed_ctl;
+	unsigned box_ctl;
+	unsigned msr_offset;
+	struct event_constraint unconstrainted;
+	struct event_constraint *constraints;
+	struct intel_uncore_pmu *pmus;
+	struct intel_uncore_ops *ops;
+	struct uncore_event_desc *event_descs;
+	const struct attribute_group *attr_groups[3];
+};
+
+#define format_group attr_groups[0]
+
+struct intel_uncore_ops {
+	void (*init_box)(struct intel_uncore_box *);
+	void (*disable_box)(struct intel_uncore_box *);
+	void (*enable_box)(struct intel_uncore_box *);
+	void (*disable_event)(struct intel_uncore_box *, struct perf_event *);
+	void (*enable_event)(struct intel_uncore_box *, struct perf_event *);
+	u64 (*read_counter)(struct intel_uncore_box *, struct perf_event *);
+};
+
+struct intel_uncore_pmu {
+	struct pmu pmu;
+	char name[UNCORE_PMU_NAME_LEN];
+	int pmu_idx;
+	int func_id;
+	struct intel_uncore_type *type;
+	struct intel_uncore_box ** __percpu box;
+};
+
+struct intel_uncore_box {
+	int phys_id;
+	int n_active;	/* number of active events */
+	int n_events;
+	int cpu;	/* cpu to collect events */
+	unsigned long flags;
+	atomic_t refcnt;
+	struct perf_event *events[UNCORE_PMC_IDX_MAX];
+	struct perf_event *event_list[UNCORE_PMC_IDX_MAX];
+	unsigned long active_mask[BITS_TO_LONGS(UNCORE_PMC_IDX_MAX)];
+	u64 tags[UNCORE_PMC_IDX_MAX];
+	struct intel_uncore_pmu *pmu;
+	struct hrtimer hrtimer;
+	struct list_head list;
+};
+
+#define UNCORE_BOX_FLAG_INITIATED	0
+
+struct uncore_event_desc {
+	struct kobj_attribute attr;
+	const char *config;
+};
+
+#define INTEL_UNCORE_EVENT_DESC(_name, _config)			\
+{								\
+	.attr	= __ATTR(_name, 0444, uncore_event_show, NULL),	\
+	.config	= _config,					\
+}
+
+#define DEFINE_UNCORE_FORMAT_ATTR(_var, _name, _format)			\
+static ssize_t __uncore_##_var##_show(struct kobject *kobj,		\
+				struct kobj_attribute *attr,		\
+				char *page)				\
+{									\
+	BUILD_BUG_ON(sizeof(_format) >= PAGE_SIZE);			\
+	return sprintf(page, _format "\n");				\
+}									\
+static struct kobj_attribute format_attr_##_var =			\
+	__ATTR(_name, 0444, __uncore_##_var##_show, NULL)
+
+
+static ssize_t uncore_event_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf)
+{
+	struct uncore_event_desc *event =
+		container_of(attr, struct uncore_event_desc, attr);
+	return sprintf(buf, "%s", event->config);
+}
+
+static inline
+unsigned uncore_msr_box_ctl(struct intel_uncore_box *box)
+{
+	if (!box->pmu->type->box_ctl)
+		return 0;
+	return box->pmu->type->box_ctl +
+		box->pmu->type->msr_offset * box->pmu->pmu_idx;
+}
+
+static inline
+unsigned uncore_msr_fixed_ctl(struct intel_uncore_box *box)
+{
+	if (!box->pmu->type->fixed_ctl)
+		return 0;
+	return box->pmu->type->fixed_ctl +
+		box->pmu->type->msr_offset * box->pmu->pmu_idx;
+}
+
+static inline
+unsigned uncore_msr_fixed_ctr(struct intel_uncore_box *box)
+{
+	return box->pmu->type->fixed_ctr +
+		box->pmu->type->msr_offset * box->pmu->pmu_idx;
+}
+
+static inline
+unsigned uncore_msr_event_ctl(struct intel_uncore_box *box, int idx)
+{
+	return idx + box->pmu->type->event_ctl +
+		box->pmu->type->msr_offset * box->pmu->pmu_idx;
+}
+
+static inline
+unsigned uncore_msr_perf_ctr(struct intel_uncore_box *box, int idx)
+{
+	return idx + box->pmu->type->perf_ctr +
+		box->pmu->type->msr_offset * box->pmu->pmu_idx;
+}
+
+static inline int uncore_perf_ctr_bits(struct intel_uncore_box *box)
+{
+	return box->pmu->type->perf_ctr_bits;
+}
+
+static inline int uncore_fixed_ctr_bits(struct intel_uncore_box *box)
+{
+	return box->pmu->type->fixed_ctr_bits;
+}
+
+static inline int uncore_num_counters(struct intel_uncore_box *box)
+{
+	return box->pmu->type->num_counters;
+}
+
+static inline void uncore_disable_box(struct intel_uncore_box *box)
+{
+	if (box->pmu->type->ops->disable_box)
+		box->pmu->type->ops->disable_box(box);
+}
+
+static inline void uncore_enable_box(struct intel_uncore_box *box)
+{
+	if (box->pmu->type->ops->enable_box)
+		box->pmu->type->ops->enable_box(box);
+}
+
+static inline void uncore_disable_event(struct intel_uncore_box *box,
+				struct perf_event *event)
+{
+	box->pmu->type->ops->disable_event(box, event);
+}
+
+static inline void uncore_enable_event(struct intel_uncore_box *box,
+				struct perf_event *event)
+{
+	box->pmu->type->ops->enable_event(box, event);
+}
+
+static inline u64 uncore_read_counter(struct intel_uncore_box *box,
+				struct perf_event *event)
+{
+	return box->pmu->type->ops->read_counter(box, event);
+}
+
+static inline void uncore_box_init(struct intel_uncore_box *box)
+{
+	if (!test_and_set_bit(UNCORE_BOX_FLAG_INITIATED, &box->flags)) {
+		if (box->pmu->type->ops->init_box)
+			box->pmu->type->ops->init_box(box);
+	}
+}