Merge branch 'perf/x86' into perf/core, because it's ready

Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/arm/kernel/hw_breakpoint.c

@@ -648,7 +648,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
 		 * Per-cpu breakpoints are not supported by our stepping
 		 * mechanism.
 		 */
-		if (!bp->hw.bp_target)
+		if (!bp->hw.target)
 			return -EINVAL;
 
 		/*

arch/arm64/kernel/hw_breakpoint.c

@@ -527,7 +527,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
 	 * Disallow per-task kernel breakpoints since these would
 	 * complicate the stepping code.
 	 */
-	if (info->ctrl.privilege == AARCH64_BREAKPOINT_EL1 && bp->hw.bp_target)
+	if (info->ctrl.privilege == AARCH64_BREAKPOINT_EL1 && bp->hw.target)
 		return -EINVAL;
 
 	return 0;

arch/x86/include/asm/cpufeature.h

@@ -12,7 +12,7 @@
 #include <asm/disabled-features.h>
 #endif
 
-#define NCAPINTS	11	/* N 32-bit words worth of info */
+#define NCAPINTS	13	/* N 32-bit words worth of info */
 #define NBUGINTS	1	/* N 32-bit bug flags */
 
 /*
@@ -226,6 +226,7 @@
 #define X86_FEATURE_ERMS	( 9*32+ 9) /* Enhanced REP MOVSB/STOSB */
 #define X86_FEATURE_INVPCID	( 9*32+10) /* Invalidate Processor Context ID */
 #define X86_FEATURE_RTM		( 9*32+11) /* Restricted Transactional Memory */
+#define X86_FEATURE_CQM		( 9*32+12) /* Cache QoS Monitoring */
 #define X86_FEATURE_MPX		( 9*32+14) /* Memory Protection Extension */
 #define X86_FEATURE_AVX512F	( 9*32+16) /* AVX-512 Foundation */
 #define X86_FEATURE_RDSEED	( 9*32+18) /* The RDSEED instruction */
@@ -242,6 +243,12 @@
 #define X86_FEATURE_XGETBV1	(10*32+ 2) /* XGETBV with ECX = 1 */
 #define X86_FEATURE_XSAVES	(10*32+ 3) /* XSAVES/XRSTORS */
 
+/* Intel-defined CPU QoS Sub-leaf, CPUID level 0x0000000F:0 (edx), word 11 */
+#define X86_FEATURE_CQM_LLC	(11*32+ 1) /* LLC QoS if 1 */
+
+/* Intel-defined CPU QoS Sub-leaf, CPUID level 0x0000000F:1 (edx), word 12 */
+#define X86_FEATURE_CQM_OCCUP_LLC (12*32+ 0) /* LLC occupancy monitoring if 1 */
+
 /*
  * BUG word(s)
  */

arch/x86/include/asm/processor.h

@@ -109,6 +109,9 @@ struct cpuinfo_x86 {
 	/* in KB - valid for CPUS which support this call: */
 	int			x86_cache_size;
 	int			x86_cache_alignment;	/* In bytes */
+	/* Cache QoS architectural values: */
+	int			x86_cache_max_rmid;	/* max index */
+	int			x86_cache_occ_scale;	/* scale to bytes */
 	int			x86_power;
 	unsigned long		loops_per_jiffy;
 	/* cpuid returned max cores value: */

arch/x86/kernel/cpu/Makefile

@@ -39,7 +39,7 @@ obj-$(CONFIG_CPU_SUP_AMD)		+= perf_event_amd_iommu.o
 endif
 obj-$(CONFIG_CPU_SUP_INTEL)		+= perf_event_p6.o perf_event_knc.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_rapl.o
+obj-$(CONFIG_CPU_SUP_INTEL)		+= perf_event_intel_rapl.o perf_event_intel_cqm.o
 
 obj-$(CONFIG_PERF_EVENTS_INTEL_UNCORE)	+= perf_event_intel_uncore.o \
 					   perf_event_intel_uncore_snb.o \

arch/x86/kernel/cpu/common.c

@@ -646,6 +646,30 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
 		c->x86_capability[10] = eax;
 	}
 
+	/* Additional Intel-defined flags: level 0x0000000F */
+	if (c->cpuid_level >= 0x0000000F) {
+		u32 eax, ebx, ecx, edx;
+
+		/* QoS sub-leaf, EAX=0Fh, ECX=0 */
+		cpuid_count(0x0000000F, 0, &eax, &ebx, &ecx, &edx);
+		c->x86_capability[11] = edx;
+		if (cpu_has(c, X86_FEATURE_CQM_LLC)) {
+			/* will be overridden if occupancy monitoring exists */
+			c->x86_cache_max_rmid = ebx;
+
+			/* QoS sub-leaf, EAX=0Fh, ECX=1 */
+			cpuid_count(0x0000000F, 1, &eax, &ebx, &ecx, &edx);
+			c->x86_capability[12] = edx;
+			if (cpu_has(c, X86_FEATURE_CQM_OCCUP_LLC)) {
+				c->x86_cache_max_rmid = ecx;
+				c->x86_cache_occ_scale = ebx;
+			}
+		} else {
+			c->x86_cache_max_rmid = -1;
+			c->x86_cache_occ_scale = -1;
+		}
+	}
+
 	/* AMD-defined flags: level 0x80000001 */
 	xlvl = cpuid_eax(0x80000000);
 	c->extended_cpuid_level = xlvl;
@@ -834,6 +858,20 @@ static void generic_identify(struct cpuinfo_x86 *c)
 	detect_nopl(c);
 }
 
+static void x86_init_cache_qos(struct cpuinfo_x86 *c)
+{
+	/*
+	 * The heavy lifting of max_rmid and cache_occ_scale are handled
+	 * in get_cpu_cap().  Here we just set the max_rmid for the boot_cpu
+	 * in case CQM bits really aren't there in this CPU.
+	 */
+	if (c != &boot_cpu_data) {
+		boot_cpu_data.x86_cache_max_rmid =
+			min(boot_cpu_data.x86_cache_max_rmid,
+			    c->x86_cache_max_rmid);
+	}
+}
+
 /*
  * This does the hard work of actually picking apart the CPU stuff...
  */
@@ -923,6 +961,7 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 
 	init_hypervisor(c);
 	x86_init_rdrand(c);
+	x86_init_cache_qos(c);
 
 	/*
 	 * Clear/Set all flags overriden by options, need do it

arch/x86/kernel/cpu/perf_event_intel_cqm.c

+/*
+ * Intel Cache Quality-of-Service Monitoring (CQM) support.
+ *
+ * Based very, very heavily on work by Peter Zijlstra.
+ */
+
+#include <linux/perf_event.h>
+#include <linux/slab.h>
+#include <asm/cpu_device_id.h>
+#include "perf_event.h"
+
+#define MSR_IA32_PQR_ASSOC	0x0c8f
+#define MSR_IA32_QM_CTR		0x0c8e
+#define MSR_IA32_QM_EVTSEL	0x0c8d
+
+static unsigned int cqm_max_rmid = -1;
+static unsigned int cqm_l3_scale; /* supposedly cacheline size */
+
+struct intel_cqm_state {
+	raw_spinlock_t		lock;
+	int			rmid;
+	int			cnt;
+};
+
+static DEFINE_PER_CPU(struct intel_cqm_state, cqm_state);
+
+/*
+ * Protects cache_cgroups and cqm_rmid_free_lru and cqm_rmid_limbo_lru.
+ * Also protects event->hw.cqm_rmid
+ *
+ * Hold either for stability, both for modification of ->hw.cqm_rmid.
+ */
+static DEFINE_MUTEX(cache_mutex);
+static DEFINE_RAW_SPINLOCK(cache_lock);
+
+/*
+ * Groups of events that have the same target(s), one RMID per group.
+ */
+static LIST_HEAD(cache_groups);
+
+/*
+ * Mask of CPUs for reading CQM values. We only need one per-socket.
+ */
+static cpumask_t cqm_cpumask;
+
+#define RMID_VAL_ERROR		(1ULL << 63)
+#define RMID_VAL_UNAVAIL	(1ULL << 62)
+
+#define QOS_L3_OCCUP_EVENT_ID	(1 << 0)
+
+#define QOS_EVENT_MASK	QOS_L3_OCCUP_EVENT_ID
+
+/*
+ * This is central to the rotation algorithm in __intel_cqm_rmid_rotate().
+ *
+ * This rmid is always free and is guaranteed to have an associated
+ * near-zero occupancy value, i.e. no cachelines are tagged with this
+ * RMID, once __intel_cqm_rmid_rotate() returns.
+ */
+static unsigned int intel_cqm_rotation_rmid;
+
+#define INVALID_RMID		(-1)
+
+/*
+ * Is @rmid valid for programming the hardware?
+ *
+ * rmid 0 is reserved by the hardware for all non-monitored tasks, which
+ * means that we should never come across an rmid with that value.
+ * Likewise, an rmid value of -1 is used to indicate "no rmid currently
+ * assigned" and is used as part of the rotation code.
+ */
+static inline bool __rmid_valid(unsigned int rmid)
+{
+	if (!rmid || rmid == INVALID_RMID)
+		return false;
+
+	return true;
+}
+
+static u64 __rmid_read(unsigned int rmid)
+{
+	u64 val;
+
+	/*
+	 * Ignore the SDM, this thing is _NOTHING_ like a regular perfcnt,
+	 * it just says that to increase confusion.
+	 */
+	wrmsr(MSR_IA32_QM_EVTSEL, QOS_L3_OCCUP_EVENT_ID, rmid);
+	rdmsrl(MSR_IA32_QM_CTR, val);
+
+	/*
+	 * Aside from the ERROR and UNAVAIL bits, assume this thing returns
+	 * the number of cachelines tagged with @rmid.
+	 */
+	return val;
+}
+
+enum rmid_recycle_state {
+	RMID_YOUNG = 0,
+	RMID_AVAILABLE,
+	RMID_DIRTY,
+};
+
+struct cqm_rmid_entry {
+	unsigned int rmid;
+	enum rmid_recycle_state state;
+	struct list_head list;
+	unsigned long queue_time;
+};
+
+/*
+ * cqm_rmid_free_lru - A least recently used list of RMIDs.
+ *
+ * Oldest entry at the head, newest (most recently used) entry at the
+ * tail. This list is never traversed, it's only used to keep track of
+ * the lru order. That is, we only pick entries of the head or insert
+ * them on the tail.
+ *
+ * All entries on the list are 'free', and their RMIDs are not currently
+ * in use. To mark an RMID as in use, remove its entry from the lru
+ * list.
+ *
+ *
+ * cqm_rmid_limbo_lru - list of currently unused but (potentially) dirty RMIDs.
+ *
+ * This list is contains RMIDs that no one is currently using but that
+ * may have a non-zero occupancy value associated with them. The
+ * rotation worker moves RMIDs from the limbo list to the free list once
+ * the occupancy value drops below __intel_cqm_threshold.
+ *
+ * Both lists are protected by cache_mutex.
+ */
+static LIST_HEAD(cqm_rmid_free_lru);
+static LIST_HEAD(cqm_rmid_limbo_lru);
+
+/*
+ * We use a simple array of pointers so that we can lookup a struct
+ * cqm_rmid_entry in O(1). This alleviates the callers of __get_rmid()
+ * and __put_rmid() from having to worry about dealing with struct
+ * cqm_rmid_entry - they just deal with rmids, i.e. integers.
+ *
+ * Once this array is initialized it is read-only. No locks are required
+ * to access it.
+ *
+ * All entries for all RMIDs can be looked up in the this array at all
+ * times.
+ */
+static struct cqm_rmid_entry **cqm_rmid_ptrs;
+
+static inline struct cqm_rmid_entry *__rmid_entry(int rmid)
+{
+	struct cqm_rmid_entry *entry;
+
+	entry = cqm_rmid_ptrs[rmid];
+	WARN_ON(entry->rmid != rmid);
+
+	return entry;
+}
+
+/*
+ * Returns < 0 on fail.
+ *
+ * We expect to be called with cache_mutex held.
+ */
+static int __get_rmid(void)
+{
+	struct cqm_rmid_entry *entry;
+
+	lockdep_assert_held(&cache_mutex);
+
+	if (list_empty(&cqm_rmid_free_lru))
+		return INVALID_RMID;
+
+	entry = list_first_entry(&cqm_rmid_free_lru, struct cqm_rmid_entry, list);
+	list_del(&entry->list);
+
+	return entry->rmid;
+}
+
+static void __put_rmid(unsigned int rmid)
+{
+	struct cqm_rmid_entry *entry;
+
+	lockdep_assert_held(&cache_mutex);
+
+	WARN_ON(!__rmid_valid(rmid));
+	entry = __rmid_entry(rmid);
+
+	entry->queue_time = jiffies;
+	entry->state = RMID_YOUNG;
+
+	list_add_tail(&entry->list, &cqm_rmid_limbo_lru);
+}
+
+static int intel_cqm_setup_rmid_cache(void)
+{
+	struct cqm_rmid_entry *entry;
+	unsigned int nr_rmids;
+	int r = 0;
+
+	nr_rmids = cqm_max_rmid + 1;
+	cqm_rmid_ptrs = kmalloc(sizeof(struct cqm_rmid_entry *) *
+				nr_rmids, GFP_KERNEL);
+	if (!cqm_rmid_ptrs)
+		return -ENOMEM;
+
+	for (; r <= cqm_max_rmid; r++) {
+		struct cqm_rmid_entry *entry;
+
+		entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+		if (!entry)
+			goto fail;
+
+		INIT_LIST_HEAD(&entry->list);
+		entry->rmid = r;
+		cqm_rmid_ptrs[r] = entry;
+
+		list_add_tail(&entry->list, &cqm_rmid_free_lru);
+	}
+
+	/*
+	 * RMID 0 is special and is always allocated. It's used for all
+	 * tasks that are not monitored.
+	 */
+	entry = __rmid_entry(0);
+	list_del(&entry->list);
+
+	mutex_lock(&cache_mutex);
+	intel_cqm_rotation_rmid = __get_rmid();
+	mutex_unlock(&cache_mutex);
+
+	return 0;
+fail:
+	while (r--)
+		kfree(cqm_rmid_ptrs[r]);
+
+	kfree(cqm_rmid_ptrs);
+	return -ENOMEM;
+}
+
+/*
+ * Determine if @a and @b measure the same set of tasks.
+ *
+ * If @a and @b measure the same set of tasks then we want to share a
+ * single RMID.
+ */
+static bool __match_event(struct perf_event *a, struct perf_event *b)
+{
+	/* Per-cpu and task events don't mix */
+	if ((a->attach_state & PERF_ATTACH_TASK) !=
+	    (b->attach_state & PERF_ATTACH_TASK))
+		return false;
+
+#ifdef CONFIG_CGROUP_PERF
+	if (a->cgrp != b->cgrp)
+		return false;
+#endif
+
+	/* If not task event, we're machine wide */
+	if (!(b->attach_state & PERF_ATTACH_TASK))
+		return true;
+
+	/*
+	 * Events that target same task are placed into the same cache group.
+	 */
+	if (a->hw.target == b->hw.target)
+		return true;
+
+	/*
+	 * Are we an inherited event?
+	 */
+	if (b->parent == a)
+		return true;
+
+	return false;
+}
+
+#ifdef CONFIG_CGROUP_PERF
+static inline struct perf_cgroup *event_to_cgroup(struct perf_event *event)
+{
+	if (event->attach_state & PERF_ATTACH_TASK)
+		return perf_cgroup_from_task(event->hw.target);
+
+	return event->cgrp;
+}
+#endif
+
+/*
+ * Determine if @a's tasks intersect with @b's tasks
+ *
+ * There are combinations of events that we explicitly prohibit,
+ *
+ *		   PROHIBITS
+ *     system-wide    -> 	cgroup and task
+ *     cgroup 	      ->	system-wide
+ *     		      ->	task in cgroup
+ *     task 	      -> 	system-wide
+ *     		      ->	task in cgroup
+ *
+ * Call this function before allocating an RMID.
+ */
+static bool __conflict_event(struct perf_event *a, struct perf_event *b)
+{
+#ifdef CONFIG_CGROUP_PERF
+	/*
+	 * We can have any number of cgroups but only one system-wide
+	 * event at a time.
+	 */
+	if (a->cgrp && b->cgrp) {
+		struct perf_cgroup *ac = a->cgrp;
+		struct perf_cgroup *bc = b->cgrp;
+
+		/*
+		 * This condition should have been caught in
+		 * __match_event() and we should be sharing an RMID.
+		 */
+		WARN_ON_ONCE(ac == bc);
+
+		if (cgroup_is_descendant(ac->css.cgroup, bc->css.cgroup) ||
+		    cgroup_is_descendant(bc->css.cgroup, ac->css.cgroup))
+			return true;
+
+		return false;
+	}
+
+	if (a->cgrp || b->cgrp) {
+		struct perf_cgroup *ac, *bc;
+
+		/*
+		 * cgroup and system-wide events are mutually exclusive
+		 */
+		if ((a->cgrp && !(b->attach_state & PERF_ATTACH_TASK)) ||
+		    (b->cgrp && !(a->attach_state & PERF_ATTACH_TASK)))
+			return true;
+
+		/*
+		 * Ensure neither event is part of the other's cgroup
+		 */
+		ac = event_to_cgroup(a);
+		bc = event_to_cgroup(b);
+		if (ac == bc)
+			return true;
+
+		/*
+		 * Must have cgroup and non-intersecting task events.
+		 */
+		if (!ac || !bc)
+			return false;
+
+		/*
+		 * We have cgroup and task events, and the task belongs
+		 * to a cgroup. Check for for overlap.
+		 */
+		if (cgroup_is_descendant(ac->css.cgroup, bc->css.cgroup) ||
+		    cgroup_is_descendant(bc->css.cgroup, ac->css.cgroup))
+			return true;
+
+		return false;
+	}
+#endif
+	/*
+	 * If one of them is not a task, same story as above with cgroups.
+	 */
+	if (!(a->attach_state & PERF_ATTACH_TASK) ||
+	    !(b->attach_state & PERF_ATTACH_TASK))
+		return true;
+
+	/*
+	 * Must be non-overlapping.
+	 */
+	return false;
+}
+
+struct rmid_read {
+	unsigned int rmid;
+	atomic64_t value;
+};
+
+static void __intel_cqm_event_count(void *info);
+
+/*
+ * Exchange the RMID of a group of events.
+ */
+static unsigned int
+intel_cqm_xchg_rmid(struct perf_event *group, unsigned int rmid)
+{
+	struct perf_event *event;
+	unsigned int old_rmid = group->hw.cqm_rmid;
+	struct list_head *head = &group->hw.cqm_group_entry;
+
+	lockdep_assert_held(&cache_mutex);
+
+	/*
+	 * If our RMID is being deallocated, perform a read now.
+	 */
+	if (__rmid_valid(old_rmid) && !__rmid_valid(rmid)) {
+		struct rmid_read rr = {
+			.value = ATOMIC64_INIT(0),
+			.rmid = old_rmid,
+		};
+
+		on_each_cpu_mask(&cqm_cpumask, __intel_cqm_event_count,
+				 &rr, 1);
+		local64_set(&group->count, atomic64_read(&rr.value));
+	}
+
+	raw_spin_lock_irq(&cache_lock);
+
+	group->hw.cqm_rmid = rmid;
+	list_for_each_entry(event, head, hw.cqm_group_entry)
+		event->hw.cqm_rmid = rmid;
+
+	raw_spin_unlock_irq(&cache_lock);
+
+	return old_rmid;
+}
+
+/*
+ * If we fail to assign a new RMID for intel_cqm_rotation_rmid because
+ * cachelines are still tagged with RMIDs in limbo, we progressively
+ * increment the threshold until we find an RMID in limbo with <=
+ * __intel_cqm_threshold lines tagged. This is designed to mitigate the
+ * problem where cachelines tagged with an RMID are not steadily being
+ * evicted.
+ *
+ * On successful rotations we decrease the threshold back towards zero.
+ *
+ * __intel_cqm_max_threshold provides an upper bound on the threshold,
+ * and is measured in bytes because it's exposed to userland.
+ */
+static unsigned int __intel_cqm_threshold;
+static unsigned int __intel_cqm_max_threshold;
+
+/*
+ * Test whether an RMID has a zero occupancy value on this cpu.
+ */
+static void intel_cqm_stable(void *arg)
+{
+	struct cqm_rmid_entry *entry;
+
+	list_for_each_entry(entry, &cqm_rmid_limbo_lru, list) {
+		if (entry->state != RMID_AVAILABLE)
+			break;
+
+		if (__rmid_read(entry->rmid) > __intel_cqm_threshold)
+			entry->state = RMID_DIRTY;
+	}
+}
+
+/*
+ * If we have group events waiting for an RMID that don't conflict with
+ * events already running, assign @rmid.
+ */
+static bool intel_cqm_sched_in_event(unsigned int rmid)
+{
+	struct perf_event *leader, *event;
+
+	lockdep_assert_held(&cache_mutex);
+
+	leader = list_first_entry(&cache_groups, struct perf_event,
+				  hw.cqm_groups_entry);
+	event = leader;
+
+	list_for_each_entry_continue(event, &cache_groups,
+				     hw.cqm_groups_entry) {
+		if (__rmid_valid(event->hw.cqm_rmid))
+			continue;
+
+		if (__conflict_event(event, leader))
+			continue;
+
+		intel_cqm_xchg_rmid(event, rmid);
+		return true;
+	}
+
+	return false;
+}
+
+/*
+ * Initially use this constant for both the limbo queue time and the
+ * rotation timer interval, pmu::hrtimer_interval_ms.
+ *
+ * They don't need to be the same, but the two are related since if you
+ * rotate faster than you recycle RMIDs, you may run out of available
+ * RMIDs.
+ */
+#define RMID_DEFAULT_QUEUE_TIME 250	/* ms */
+
+static unsigned int __rmid_queue_time_ms = RMID_DEFAULT_QUEUE_TIME;
+
+/*
+ * intel_cqm_rmid_stabilize - move RMIDs from limbo to free list
+ * @nr_available: number of freeable RMIDs on the limbo list
+ *
+ * Quiescent state; wait for all 'freed' RMIDs to become unused, i.e. no
+ * cachelines are tagged with those RMIDs. After this we can reuse them
+ * and know that the current set of active RMIDs is stable.
+ *
+ * Return %true or %false depending on whether stabilization needs to be
+ * reattempted.
+ *
+ * If we return %true then @nr_available is updated to indicate the
+ * number of RMIDs on the limbo list that have been queued for the
+ * minimum queue time (RMID_AVAILABLE), but whose data occupancy values
+ * are above __intel_cqm_threshold.
+ */
+static bool intel_cqm_rmid_stabilize(unsigned int *available)
+{
+	struct cqm_rmid_entry *entry, *tmp;
+
+	lockdep_assert_held(&cache_mutex);
+
+	*available = 0;
+	list_for_each_entry(entry, &cqm_rmid_limbo_lru, list) {
+		unsigned long min_queue_time;
+		unsigned long now = jiffies;
+
+		/*
+		 * We hold RMIDs placed into limbo for a minimum queue
+		 * time. Before the minimum queue time has elapsed we do
+		 * not recycle RMIDs.
+		 *
+		 * The reasoning is that until a sufficient time has
+		 * passed since we stopped using an RMID, any RMID
+		 * placed onto the limbo list will likely still have
+		 * data tagged in the cache, which means we'll probably
+		 * fail to recycle it anyway.
+		 *
+		 * We can save ourselves an expensive IPI by skipping
+		 * any RMIDs that have not been queued for the minimum
+		 * time.
+		 */
+		min_queue_time = entry->queue_time +
+			msecs_to_jiffies(__rmid_queue_time_ms);
+
+		if (time_after(min_queue_time, now))
+			break;
+
+		entry->state = RMID_AVAILABLE;
+		(*available)++;
+	}
+
+	/*
+	 * Fast return if none of the RMIDs on the limbo list have been
+	 * sitting on the queue for the minimum queue time.
+	 */
+	if (!*available)
+		return false;
+
+	/*
+	 * Test whether an RMID is free for each package.
+	 */
+	on_each_cpu_mask(&cqm_cpumask, intel_cqm_stable, NULL, true);
+
+	list_for_each_entry_safe(entry, tmp, &cqm_rmid_limbo_lru, list) {
+		/*
+		 * Exhausted all RMIDs that have waited min queue time.
+		 */
+		if (entry->state == RMID_YOUNG)
+			break;
+
+		if (entry->state == RMID_DIRTY)
+			continue;
+
+		list_del(&entry->list);	/* remove from limbo */
+
+		/*
+		 * The rotation RMID gets priority if it's
+		 * currently invalid. In which case, skip adding
+		 * the RMID to the the free lru.
+		 */
+		if (!__rmid_valid(intel_cqm_rotation_rmid)) {
+			intel_cqm_rotation_rmid = entry->rmid;
+			continue;
+		}
+
+		/*
+		 * If we have groups waiting for RMIDs, hand
+		 * them one now provided they don't conflict.
+		 */
+		if (intel_cqm_sched_in_event(entry->rmid))
+			continue;
+
+		/*
+		 * Otherwise place it onto the free list.
+		 */
+		list_add_tail(&entry->list, &cqm_rmid_free_lru);
+	}
+
+
+	return __rmid_valid(intel_cqm_rotation_rmid);
+}
+
+/*
+ * Pick a victim group and move it to the tail of the group list.
+ * @next: The first group without an RMID
+ */
+static void __intel_cqm_pick_and_rotate(struct perf_event *next)
+{
+	struct perf_event *rotor;
+	unsigned int rmid;
+
+	lockdep_assert_held(&cache_mutex);
+
+	rotor = list_first_entry(&cache_groups, struct perf_event,
+				 hw.cqm_groups_entry);
+
+	/*
+	 * The group at the front of the list should always have a valid
+	 * RMID. If it doesn't then no groups have RMIDs assigned and we
+	 * don't need to rotate the list.
+	 */
+	if (next == rotor)
+		return;
+
+	rmid = intel_cqm_xchg_rmid(rotor, INVALID_RMID);
+	__put_rmid(rmid);
+
+	list_rotate_left(&cache_groups);
+}
+
+/*
+ * Deallocate the RMIDs from any events that conflict with @event, and
+ * place them on the back of the group list.
+ */
+static void intel_cqm_sched_out_conflicting_events(struct perf_event *event)
+{
+	struct perf_event *group, *g;
+	unsigned int rmid;
+
+	lockdep_assert_held(&cache_mutex);
+
+	list_for_each_entry_safe(group, g, &cache_groups, hw.cqm_groups_entry) {
+		if (group == event)
+			continue;
+
+		rmid = group->hw.cqm_rmid;
+
+		/*
+		 * Skip events that don't have a valid RMID.
+		 */
+		if (!__rmid_valid(rmid))
+			continue;
+
+		/*
+		 * No conflict? No problem! Leave the event alone.
+		 */
+		if (!__conflict_event(group, event))
+			continue;
+
+		intel_cqm_xchg_rmid(group, INVALID_RMID);
+		__put_rmid(rmid);
+	}
+}
+
+/*
+ * Attempt to rotate the groups and assign new RMIDs.
+ *
+ * We rotate for two reasons,
+ *   1. To handle the scheduling of conflicting events
+ *   2. To recycle RMIDs
+ *
+ * Rotating RMIDs is complicated because the hardware doesn't give us
+ * any clues.
+ *
+ * There's problems with the hardware interface; when you change the
+ * task:RMID map cachelines retain their 'old' tags, giving a skewed
+ * picture. In order to work around this, we must always keep one free
+ * RMID - intel_cqm_rotation_rmid.
+ *
+ * Rotation works by taking away an RMID from a group (the old RMID),
+ * and assigning the free RMID to another group (the new RMID). We must
+ * then wait for the old RMID to not be used (no cachelines tagged).
+ * This ensure that all cachelines are tagged with 'active' RMIDs. At
+ * this point we can start reading values for the new RMID and treat the
+ * old RMID as the free RMID for the next rotation.
+ *
+ * Return %true or %false depending on whether we did any rotating.
+ */
+static bool __intel_cqm_rmid_rotate(void)
+{
+	struct perf_event *group, *start = NULL;
+	unsigned int threshold_limit;
+	unsigned int nr_needed = 0;
+	unsigned int nr_available;
+	bool rotated = false;
+
+	mutex_lock(&cache_mutex);
+
+again:
+	/*
+	 * Fast path through this function if there are no groups and no
+	 * RMIDs that need cleaning.
+	 */
+	if (list_empty(&cache_groups) && list_empty(&cqm_rmid_limbo_lru))
+		goto out;
+
+	list_for_each_entry(group, &cache_groups, hw.cqm_groups_entry) {
+		if (!__rmid_valid(group->hw.cqm_rmid)) {
+			if (!start)
+				start = group;
+			nr_needed++;
+		}
+	}
+
+	/*
+	 * We have some event groups, but they all have RMIDs assigned
+	 * and no RMIDs need cleaning.
+	 */
+	if (!nr_needed && list_empty(&cqm_rmid_limbo_lru))
+		goto out;
+
+	if (!nr_needed)
+		goto stabilize;
+
+	/*
+	 * We have more event groups without RMIDs than available RMIDs,
+	 * or we have event groups that conflict with the ones currently
+	 * scheduled.
+	 *
+	 * We force deallocate the rmid of the group at the head of
+	 * cache_groups. The first event group without an RMID then gets
+	 * assigned intel_cqm_rotation_rmid. This ensures we always make
+	 * forward progress.
+	 *
+	 * Rotate the cache_groups list so the previous head is now the
+	 * tail.
+	 */
+	__intel_cqm_pick_and_rotate(start);
+
+	/*
+	 * If the rotation is going to succeed, reduce the threshold so
+	 * that we don't needlessly reuse dirty RMIDs.
+	 */
+	if (__rmid_valid(intel_cqm_rotation_rmid)) {
+		intel_cqm_xchg_rmid(start, intel_cqm_rotation_rmid);
+		intel_cqm_rotation_rmid = __get_rmid();
+
+		intel_cqm_sched_out_conflicting_events(start);
+
+		if (__intel_cqm_threshold)
+			__intel_cqm_threshold--;
+	}
+
+	rotated = true;
+
+stabilize:
+	/*
+	 * We now need to stablize the RMID we freed above (if any) to
+	 * ensure that the next time we rotate we have an RMID with zero
+	 * occupancy value.
+	 *
+	 * Alternatively, if we didn't need to perform any rotation,
+	 * we'll have a bunch of RMIDs in limbo that need stabilizing.
+	 */
+	threshold_limit = __intel_cqm_max_threshold / cqm_l3_scale;
+
+	while (intel_cqm_rmid_stabilize(&nr_available) &&
+	       __intel_cqm_threshold < threshold_limit) {
+		unsigned int steal_limit;
+
+		/*
+		 * Don't spin if nobody is actively waiting for an RMID,
+		 * the rotation worker will be kicked as soon as an
+		 * event needs an RMID anyway.
+		 */
+		if (!nr_needed)
+			break;
+
+		/* Allow max 25% of RMIDs to be in limbo. */
+		steal_limit = (cqm_max_rmid + 1) / 4;
+
+		/*
+		 * We failed to stabilize any RMIDs so our rotation
+		 * logic is now stuck. In order to make forward progress
+		 * we have a few options:
+		 *
+		 *   1. rotate ("steal") another RMID
+		 *   2. increase the threshold
+		 *   3. do nothing
+		 *
+		 * We do both of 1. and 2. until we hit the steal limit.
+		 *
+		 * The steal limit prevents all RMIDs ending up on the
+		 * limbo list. This can happen if every RMID has a
+		 * non-zero occupancy above threshold_limit, and the
+		 * occupancy values aren't dropping fast enough.
+		 *
+		 * Note that there is prioritisation at work here - we'd
+		 * rather increase the number of RMIDs on the limbo list
+		 * than increase the threshold, because increasing the
+		 * threshold skews the event data (because we reuse
+		 * dirty RMIDs) - threshold bumps are a last resort.
+		 */
+		if (nr_available < steal_limit)
+			goto again;
+
+		__intel_cqm_threshold++;
+	}
+
+out:
+	mutex_unlock(&cache_mutex);
+	return rotated;
+}
+
+static void intel_cqm_rmid_rotate(struct work_struct *work);
+
+static DECLARE_DELAYED_WORK(intel_cqm_rmid_work, intel_cqm_rmid_rotate);
+
+static struct pmu intel_cqm_pmu;
+
+static void intel_cqm_rmid_rotate(struct work_struct *work)
+{
+	unsigned long delay;
+
+	__intel_cqm_rmid_rotate();
+
+	delay = msecs_to_jiffies(intel_cqm_pmu.hrtimer_interval_ms);
+	schedule_delayed_work(&intel_cqm_rmid_work, delay);
+}
+
+/*
+ * Find a group and setup RMID.
+ *
+ * If we're part of a group, we use the group's RMID.
+ */
+static void intel_cqm_setup_event(struct perf_event *event,
+				  struct perf_event **group)
+{
+	struct perf_event *iter;
+	unsigned int rmid;
+	bool conflict = false;
+
+	list_for_each_entry(iter, &cache_groups, hw.cqm_groups_entry) {
+		rmid = iter->hw.cqm_rmid;
+
+		if (__match_event(iter, event)) {
+			/* All tasks in a group share an RMID */
+			event->hw.cqm_rmid = rmid;
+			*group = iter;
+			return;
+		}
+
+		/*
+		 * We only care about conflicts for events that are
+		 * actually scheduled in (and hence have a valid RMID).
+		 */
+		if (__conflict_event(iter, event) && __rmid_valid(rmid))
+			conflict = true;
+	}
+
+	if (conflict)
+		rmid = INVALID_RMID;
+	else
+		rmid = __get_rmid();
+
+	event->hw.cqm_rmid = rmid;
+}
+
+static void intel_cqm_event_read(struct perf_event *event)
+{
+	unsigned long flags;
+	unsigned int rmid;
+	u64 val;
+
+	/*
+	 * Task events are handled by intel_cqm_event_count().
+	 */
+	if (event->cpu == -1)
+		return;
+
+	raw_spin_lock_irqsave(&cache_lock, flags);
+	rmid = event->hw.cqm_rmid;
+
+	if (!__rmid_valid(rmid))
+		goto out;
+
+	val = __rmid_read(rmid);
+
+	/*
+	 * Ignore this reading on error states and do not update the value.
+	 */
+	if (val & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL))
+		goto out;
+
+	local64_set(&event->count, val);
+out:
+	raw_spin_unlock_irqrestore(&cache_lock, flags);
+}
+
+static void __intel_cqm_event_count(void *info)
+{
+	struct rmid_read *rr = info;
+	u64 val;
+
+	val = __rmid_read(rr->rmid);
+
+	if (val & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL))
+		return;
+
+	atomic64_add(val, &rr->value);
+}
+
+static inline bool cqm_group_leader(struct perf_event *event)
+{
+	return !list_empty(&event->hw.cqm_groups_entry);
+}
+
+static u64 intel_cqm_event_count(struct perf_event *event)
+{
+	unsigned long flags;
+	struct rmid_read rr = {
+		.value = ATOMIC64_INIT(0),
+	};
+
+	/*
+	 * We only need to worry about task events. System-wide events
+	 * are handled like usual, i.e. entirely with
+	 * intel_cqm_event_read().
+	 */
+	if (event->cpu != -1)
+		return __perf_event_count(event);
+
+	/*
+	 * Only the group leader gets to report values. This stops us
+	 * reporting duplicate values to userspace, and gives us a clear
+	 * rule for which task gets to report the values.
+	 *
+	 * Note that it is impossible to attribute these values to
+	 * specific packages - we forfeit that ability when we create
+	 * task events.
+	 */
+	if (!cqm_group_leader(event))
+		return 0;
+
+	/*
+	 * Notice that we don't perform the reading of an RMID
+	 * atomically, because we can't hold a spin lock across the
+	 * IPIs.
+	 *
+	 * Speculatively perform the read, since @event might be
+	 * assigned a different (possibly invalid) RMID while we're
+	 * busying performing the IPI calls. It's therefore necessary to
+	 * check @event's RMID afterwards, and if it has changed,
+	 * discard the result of the read.
+	 */
+	rr.rmid = ACCESS_ONCE(event->hw.cqm_rmid);
+
+	if (!__rmid_valid(rr.rmid))
+		goto out;
+
+	on_each_cpu_mask(&cqm_cpumask, __intel_cqm_event_count, &rr, 1);
+
+	raw_spin_lock_irqsave(&cache_lock, flags);
+	if (event->hw.cqm_rmid == rr.rmid)
+		local64_set(&event->count, atomic64_read(&rr.value));
+	raw_spin_unlock_irqrestore(&cache_lock, flags);
+out:
+	return __perf_event_count(event);
+}
+
+static void intel_cqm_event_start(struct perf_event *event, int mode)
+{
+	struct intel_cqm_state *state = this_cpu_ptr(&cqm_state);
+	unsigned int rmid = event->hw.cqm_rmid;
+	unsigned long flags;
+
+	if (!(event->hw.cqm_state & PERF_HES_STOPPED))
+		return;
+
+	event->hw.cqm_state &= ~PERF_HES_STOPPED;
+
+	raw_spin_lock_irqsave(&state->lock, flags);
+
+	if (state->cnt++)
+		WARN_ON_ONCE(state->rmid != rmid);
+	else
+		WARN_ON_ONCE(state->rmid);
+
+	state->rmid = rmid;
+	wrmsrl(MSR_IA32_PQR_ASSOC, state->rmid);
+
+	raw_spin_unlock_irqrestore(&state->lock, flags);
+}
+
+static void intel_cqm_event_stop(struct perf_event *event, int mode)
+{
+	struct intel_cqm_state *state = this_cpu_ptr(&cqm_state);
+	unsigned long flags;
+
+	if (event->hw.cqm_state & PERF_HES_STOPPED)
+		return;
+
+	event->hw.cqm_state |= PERF_HES_STOPPED;
+
+	raw_spin_lock_irqsave(&state->lock, flags);
+	intel_cqm_event_read(event);
+
+	if (!--state->cnt) {
+		state->rmid = 0;
+		wrmsrl(MSR_IA32_PQR_ASSOC, 0);
+	} else {
+		WARN_ON_ONCE(!state->rmid);
+	}
+
+	raw_spin_unlock_irqrestore(&state->lock, flags);
+}
+
+static int intel_cqm_event_add(struct perf_event *event, int mode)
+{
+	unsigned long flags;
+	unsigned int rmid;
+
+	raw_spin_lock_irqsave(&cache_lock, flags);
+
+	event->hw.cqm_state = PERF_HES_STOPPED;
+	rmid = event->hw.cqm_rmid;
+
+	if (__rmid_valid(rmid) && (mode & PERF_EF_START))
+		intel_cqm_event_start(event, mode);
+
+	raw_spin_unlock_irqrestore(&cache_lock, flags);
+
+	return 0;
+}
+
+static void intel_cqm_event_del(struct perf_event *event, int mode)
+{
+	intel_cqm_event_stop(event, mode);
+}
+
+static void intel_cqm_event_destroy(struct perf_event *event)
+{
+	struct perf_event *group_other = NULL;
+
+	mutex_lock(&cache_mutex);
+
+	/*
+	 * If there's another event in this group...
+	 */
+	if (!list_empty(&event->hw.cqm_group_entry)) {
+		group_other = list_first_entry(&event->hw.cqm_group_entry,
+					       struct perf_event,
+					       hw.cqm_group_entry);
+		list_del(&event->hw.cqm_group_entry);
+	}
+
+	/*
+	 * And we're the group leader..
+	 */
+	if (cqm_group_leader(event)) {
+		/*
+		 * If there was a group_other, make that leader, otherwise
+		 * destroy the group and return the RMID.
+		 */
+		if (group_other) {
+			list_replace(&event->hw.cqm_groups_entry,
+				     &group_other->hw.cqm_groups_entry);
+		} else {
+			unsigned int rmid = event->hw.cqm_rmid;
+
+			if (__rmid_valid(rmid))
+				__put_rmid(rmid);
+			list_del(&event->hw.cqm_groups_entry);
+		}
+	}
+
+	mutex_unlock(&cache_mutex);
+}
+
+static int intel_cqm_event_init(struct perf_event *event)
+{
+	struct perf_event *group = NULL;
+	bool rotate = false;
+
+	if (event->attr.type != intel_cqm_pmu.type)
+		return -ENOENT;
+
+	if (event->attr.config & ~QOS_EVENT_MASK)
+		return -EINVAL;
+
+	/* unsupported modes and filters */
+	if (event->attr.exclude_user   ||
+	    event->attr.exclude_kernel ||
+	    event->attr.exclude_hv     ||
+	    event->attr.exclude_idle   ||
+	    event->attr.exclude_host   ||
+	    event->attr.exclude_guest  ||
+	    event->attr.sample_period) /* no sampling */
+		return -EINVAL;
+
+	INIT_LIST_HEAD(&event->hw.cqm_group_entry);
+	INIT_LIST_HEAD(&event->hw.cqm_groups_entry);
+
+	event->destroy = intel_cqm_event_destroy;
+
+	mutex_lock(&cache_mutex);
+
+	/* Will also set rmid */
+	intel_cqm_setup_event(event, &group);
+
+	if (group) {
+		list_add_tail(&event->hw.cqm_group_entry,
+			      &group->hw.cqm_group_entry);
+	} else {
+		list_add_tail(&event->hw.cqm_groups_entry,
+			      &cache_groups);
+
+		/*
+		 * All RMIDs are either in use or have recently been
+		 * used. Kick the rotation worker to clean/free some.
+		 *
+		 * We only do this for the group leader, rather than for
+		 * every event in a group to save on needless work.
+		 */
+		if (!__rmid_valid(event->hw.cqm_rmid))
+			rotate = true;
+	}
+
+	mutex_unlock(&cache_mutex);
+
+	if (rotate)
+		schedule_delayed_work(&intel_cqm_rmid_work, 0);
+
+	return 0;
+}
+
+EVENT_ATTR_STR(llc_occupancy, intel_cqm_llc, "event=0x01");
+EVENT_ATTR_STR(llc_occupancy.per-pkg, intel_cqm_llc_pkg, "1");
+EVENT_ATTR_STR(llc_occupancy.unit, intel_cqm_llc_unit, "Bytes");
+EVENT_ATTR_STR(llc_occupancy.scale, intel_cqm_llc_scale, NULL);
+EVENT_ATTR_STR(llc_occupancy.snapshot, intel_cqm_llc_snapshot, "1");
+
+static struct attribute *intel_cqm_events_attr[] = {
+	EVENT_PTR(intel_cqm_llc),
+	EVENT_PTR(intel_cqm_llc_pkg),
+	EVENT_PTR(intel_cqm_llc_unit),
+	EVENT_PTR(intel_cqm_llc_scale),
+	EVENT_PTR(intel_cqm_llc_snapshot),
+	NULL,
+};
+
+static struct attribute_group intel_cqm_events_group = {
+	.name = "events",
+	.attrs = intel_cqm_events_attr,
+};
+
+PMU_FORMAT_ATTR(event, "config:0-7");
+static struct attribute *intel_cqm_formats_attr[] = {
+	&format_attr_event.attr,
+	NULL,
+};
+
+static struct attribute_group intel_cqm_format_group = {
+	.name = "format",
+	.attrs = intel_cqm_formats_attr,
+};
+
+static ssize_t
+max_recycle_threshold_show(struct device *dev, struct device_attribute *attr,
+			   char *page)
+{
+	ssize_t rv;
+
+	mutex_lock(&cache_mutex);
+	rv = snprintf(page, PAGE_SIZE-1, "%u\n", __intel_cqm_max_threshold);
+	mutex_unlock(&cache_mutex);
+
+	return rv;
+}
+
+static ssize_t
+max_recycle_threshold_store(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	unsigned int bytes, cachelines;
+	int ret;
+
+	ret = kstrtouint(buf, 0, &bytes);
+	if (ret)
+		return ret;
+
+	mutex_lock(&cache_mutex);
+
+	__intel_cqm_max_threshold = bytes;
+	cachelines = bytes / cqm_l3_scale;
+
+	/*
+	 * The new maximum takes effect immediately.
+	 */
+	if (__intel_cqm_threshold > cachelines)
+		__intel_cqm_threshold = cachelines;
+
+	mutex_unlock(&cache_mutex);
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(max_recycle_threshold);
+
+static struct attribute *intel_cqm_attrs[] = {
+	&dev_attr_max_recycle_threshold.attr,
+	NULL,
+};
+
+static const struct attribute_group intel_cqm_group = {
+	.attrs = intel_cqm_attrs,
+};
+
+static const struct attribute_group *intel_cqm_attr_groups[] = {
+	&intel_cqm_events_group,
+	&intel_cqm_format_group,
+	&intel_cqm_group,
+	NULL,
+};
+
+static struct pmu intel_cqm_pmu = {
+	.hrtimer_interval_ms = RMID_DEFAULT_QUEUE_TIME,
+	.attr_groups	     = intel_cqm_attr_groups,
+	.task_ctx_nr	     = perf_sw_context,
+	.event_init	     = intel_cqm_event_init,
+	.add		     = intel_cqm_event_add,
+	.del		     = intel_cqm_event_del,
+	.start		     = intel_cqm_event_start,
+	.stop		     = intel_cqm_event_stop,
+	.read		     = intel_cqm_event_read,
+	.count		     = intel_cqm_event_count,
+};
+
+static inline void cqm_pick_event_reader(int cpu)
+{
+	int phys_id = topology_physical_package_id(cpu);
+	int i;
+
+	for_each_cpu(i, &cqm_cpumask) {
+		if (phys_id == topology_physical_package_id(i))
+			return;	/* already got reader for this socket */
+	}
+
+	cpumask_set_cpu(cpu, &cqm_cpumask);
+}
+
+static void intel_cqm_cpu_prepare(unsigned int cpu)
+{
+	struct intel_cqm_state *state = &per_cpu(cqm_state, cpu);
+	struct cpuinfo_x86 *c = &cpu_data(cpu);
+
+	raw_spin_lock_init(&state->lock);
+	state->rmid = 0;
+	state->cnt  = 0;
+
+	WARN_ON(c->x86_cache_max_rmid != cqm_max_rmid);
+	WARN_ON(c->x86_cache_occ_scale != cqm_l3_scale);
+}
+
+static void intel_cqm_cpu_exit(unsigned int cpu)
+{
+	int phys_id = topology_physical_package_id(cpu);
+	int i;
+
+	/*
+	 * Is @cpu a designated cqm reader?
+	 */
+	if (!cpumask_test_and_clear_cpu(cpu, &cqm_cpumask))
+		return;
+
+	for_each_online_cpu(i) {
+		if (i == cpu)
+			continue;
+
+		if (phys_id == topology_physical_package_id(i)) {
+			cpumask_set_cpu(i, &cqm_cpumask);
+			break;
+		}
+	}
+}
+
+static int intel_cqm_cpu_notifier(struct notifier_block *nb,
+				  unsigned long action, void *hcpu)
+{
+	unsigned int cpu  = (unsigned long)hcpu;
+
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_UP_PREPARE:
+		intel_cqm_cpu_prepare(cpu);
+		break;
+	case CPU_DOWN_PREPARE:
+		intel_cqm_cpu_exit(cpu);
+		break;
+	case CPU_STARTING:
+		cqm_pick_event_reader(cpu);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static const struct x86_cpu_id intel_cqm_match[] = {
+	{ .vendor = X86_VENDOR_INTEL, .feature = X86_FEATURE_CQM_OCCUP_LLC },
+	{}
+};
+
+static int __init intel_cqm_init(void)
+{
+	char *str, scale[20];
+	int i, cpu, ret;
+
+	if (!x86_match_cpu(intel_cqm_match))
+		return -ENODEV;
+
+	cqm_l3_scale = boot_cpu_data.x86_cache_occ_scale;
+
+	/*
+	 * It's possible that not all resources support the same number
+	 * of RMIDs. Instead of making scheduling much more complicated
+	 * (where we have to match a task's RMID to a cpu that supports
+	 * that many RMIDs) just find the minimum RMIDs supported across
+	 * all cpus.
+	 *
+	 * Also, check that the scales match on all cpus.
+	 */
+	cpu_notifier_register_begin();
+
+	for_each_online_cpu(cpu) {
+		struct cpuinfo_x86 *c = &cpu_data(cpu);
+
+		if (c->x86_cache_max_rmid < cqm_max_rmid)
+			cqm_max_rmid = c->x86_cache_max_rmid;
+
+		if (c->x86_cache_occ_scale != cqm_l3_scale) {
+			pr_err("Multiple LLC scale values, disabling\n");
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+	/*
+	 * A reasonable upper limit on the max threshold is the number
+	 * of lines tagged per RMID if all RMIDs have the same number of
+	 * lines tagged in the LLC.
+	 *
+	 * For a 35MB LLC and 56 RMIDs, this is ~1.8% of the LLC.
+	 */
+	__intel_cqm_max_threshold =
+		boot_cpu_data.x86_cache_size * 1024 / (cqm_max_rmid + 1);
+
+	snprintf(scale, sizeof(scale), "%u", cqm_l3_scale);
+	str = kstrdup(scale, GFP_KERNEL);
+	if (!str) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	event_attr_intel_cqm_llc_scale.event_str = str;
+
+	ret = intel_cqm_setup_rmid_cache();
+	if (ret)
+		goto out;
+
+	for_each_online_cpu(i) {
+		intel_cqm_cpu_prepare(i);
+		cqm_pick_event_reader(i);
+	}
+
+	__perf_cpu_notifier(intel_cqm_cpu_notifier);
+
+	ret = perf_pmu_register(&intel_cqm_pmu, "intel_cqm", -1);
+	if (ret)
+		pr_err("Intel CQM perf registration failed: %d\n", ret);
+	else
+		pr_info("Intel CQM monitoring enabled\n");
+
+out:
+	cpu_notifier_register_done();
+
+	return ret;
+}
+device_initcall(intel_cqm_init);

include/linux/perf_event.h

@@ -53,6 +53,7 @@ struct perf_guest_info_callbacks {
 #include <linux/sysfs.h>
 #include <linux/perf_regs.h>
 #include <linux/workqueue.h>
+#include <linux/cgroup.h>
 #include <asm/local.h>
 
 struct perf_callchain_entry {
@@ -118,10 +119,16 @@ struct hw_perf_event {
 			struct hrtimer	hrtimer;
 		};
 		struct { /* tracepoint */
-			struct task_struct	*tp_target;
 			/* for tp_event->class */
 			struct list_head	tp_list;
 		};
+		struct { /* intel_cqm */
+			int			cqm_state;
+			int			cqm_rmid;
+			struct list_head	cqm_events_entry;
+			struct list_head	cqm_groups_entry;
+			struct list_head	cqm_group_entry;
+		};
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 		struct { /* breakpoint */
 			/*
@@ -129,12 +136,12 @@ struct hw_perf_event {
 			 * problem hw_breakpoint has with context
 			 * creation and event initalization.
 			 */
-			struct task_struct		*bp_target;
 			struct arch_hw_breakpoint	info;
 			struct list_head		bp_list;
 		};
 #endif
 	};
+	struct task_struct		*target;
 	int				state;
 	local64_t			prev_count;
 	u64				sample_period;
@@ -271,6 +278,11 @@ struct pmu {
 	 */
 	size_t				task_ctx_size;
 
+
+	/*
+	 * Return the count value for a counter.
+	 */
+	u64 (*count)			(struct perf_event *event); /*optional*/
 };
 
 /**
@@ -547,6 +559,35 @@ struct perf_output_handle {
 	int				page;
 };
 
+#ifdef CONFIG_CGROUP_PERF
+
+/*
+ * perf_cgroup_info keeps track of time_enabled for a cgroup.
+ * This is a per-cpu dynamically allocated data structure.
+ */
+struct perf_cgroup_info {
+	u64				time;
+	u64				timestamp;
+};
+
+struct perf_cgroup {
+	struct cgroup_subsys_state	css;
+	struct perf_cgroup_info	__percpu *info;
+};
+
+/*
+ * Must ensure cgroup is pinned (css_get) before calling
+ * this function. In other words, we cannot call this function
+ * if there is no cgroup event for the current CPU context.
+ */
+static inline struct perf_cgroup *
+perf_cgroup_from_task(struct task_struct *task)
+{
+	return container_of(task_css(task, perf_event_cgrp_id),
+			    struct perf_cgroup, css);
+}
+#endif /* CONFIG_CGROUP_PERF */
+
 #ifdef CONFIG_PERF_EVENTS
 
 extern int perf_pmu_register(struct pmu *pmu, const char *name, int type);
@@ -740,6 +781,11 @@ static inline void perf_event_task_sched_out(struct task_struct *prev,
 		__perf_event_task_sched_out(prev, next);
 }
 
+static inline u64 __perf_event_count(struct perf_event *event)
+{
+	return local64_read(&event->count) + atomic64_read(&event->child_count);
+}
+
 extern void perf_event_mmap(struct vm_area_struct *vma);
 extern struct perf_guest_info_callbacks *perf_guest_cbs;
 extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);

kernel/events/core.c

@@ -34,11 +34,11 @@
 #include <linux/syscalls.h>
 #include <linux/anon_inodes.h>
 #include <linux/kernel_stat.h>
+#include <linux/cgroup.h>
 #include <linux/perf_event.h>
 #include <linux/ftrace_event.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/mm_types.h>
-#include <linux/cgroup.h>
 #include <linux/module.h>
 #include <linux/mman.h>
 #include <linux/compat.h>
@@ -351,32 +351,6 @@ static void perf_ctx_unlock(struct perf_cpu_context *cpuctx,
 
 #ifdef CONFIG_CGROUP_PERF
 
-/*
- * perf_cgroup_info keeps track of time_enabled for a cgroup.
- * This is a per-cpu dynamically allocated data structure.
- */
-struct perf_cgroup_info {
-	u64				time;
-	u64				timestamp;
-};
-
-struct perf_cgroup {
-	struct cgroup_subsys_state	css;
-	struct perf_cgroup_info	__percpu *info;
-};
-
-/*
- * Must ensure cgroup is pinned (css_get) before calling
- * this function. In other words, we cannot call this function
- * if there is no cgroup event for the current CPU context.
- */
-static inline struct perf_cgroup *
-perf_cgroup_from_task(struct task_struct *task)
-{
-	return container_of(task_css(task, perf_event_cgrp_id),
-			    struct perf_cgroup, css);
-}
-
 static inline bool
 perf_cgroup_match(struct perf_event *event)
 {
@@ -3220,7 +3194,10 @@ static void __perf_event_read(void *info)
 
 static inline u64 perf_event_count(struct perf_event *event)
 {
-	return local64_read(&event->count) + atomic64_read(&event->child_count);
+	if (event->pmu->count)
+		return event->pmu->count(event);
+
+	return __perf_event_count(event);
 }
 
 static u64 perf_event_read(struct perf_event *event)
@@ -7149,7 +7126,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 		 struct perf_event *group_leader,
 		 struct perf_event *parent_event,
 		 perf_overflow_handler_t overflow_handler,
-		 void *context)
+		 void *context, int cgroup_fd)
 {
 	struct pmu *pmu;
 	struct perf_event *event;
@@ -7204,16 +7181,12 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 
 	if (task) {
 		event->attach_state = PERF_ATTACH_TASK;
-
-		if (attr->type == PERF_TYPE_TRACEPOINT)
-			event->hw.tp_target = task;
-#ifdef CONFIG_HAVE_HW_BREAKPOINT
 		/*
-		 * hw_breakpoint is a bit difficult here..
+		 * XXX pmu::event_init needs to know what task to account to
+		 * and we cannot use the ctx information because we need the
+		 * pmu before we get a ctx.
 		 */
-		else if (attr->type == PERF_TYPE_BREAKPOINT)
-			event->hw.bp_target = task;
-#endif
+		event->hw.target = task;
 	}
 
 	if (!overflow_handler && parent_event) {
@@ -7245,6 +7218,12 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 	if (!has_branch_stack(event))
 		event->attr.branch_sample_type = 0;
 
+	if (cgroup_fd != -1) {
+		err = perf_cgroup_connect(cgroup_fd, event, attr, group_leader);
+		if (err)
+			goto err_ns;
+	}
+
 	pmu = perf_init_event(event);
 	if (!pmu)
 		goto err_ns;
@@ -7268,6 +7247,8 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 		event->destroy(event);
 	module_put(pmu->module);
 err_ns:
+	if (is_cgroup_event(event))
+		perf_detach_cgroup(event);
 	if (event->ns)
 		put_pid_ns(event->ns);
 	kfree(event);
@@ -7486,6 +7467,7 @@ SYSCALL_DEFINE5(perf_event_open,
 	int move_group = 0;
 	int err;
 	int f_flags = O_RDWR;
+	int cgroup_fd = -1;
 
 	/* for future expandability... */
 	if (flags & ~PERF_FLAG_ALL)
@@ -7551,21 +7533,16 @@ SYSCALL_DEFINE5(perf_event_open,
 
 	get_online_cpus();
 
+	if (flags & PERF_FLAG_PID_CGROUP)
+		cgroup_fd = pid;
+
 	event = perf_event_alloc(&attr, cpu, task, group_leader, NULL,
-				 NULL, NULL);
+				 NULL, NULL, cgroup_fd);
 	if (IS_ERR(event)) {
 		err = PTR_ERR(event);
 		goto err_cpus;
 	}
 
-	if (flags & PERF_FLAG_PID_CGROUP) {
-		err = perf_cgroup_connect(pid, event, &attr, group_leader);
-		if (err) {
-			__free_event(event);
-			goto err_cpus;
-		}
-	}
-
 	if (is_sampling_event(event)) {
 		if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) {
 			err = -ENOTSUPP;
@@ -7802,7 +7779,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
 	 */
 
 	event = perf_event_alloc(attr, cpu, task, NULL, NULL,
-				 overflow_handler, context);
+				 overflow_handler, context, -1);
 	if (IS_ERR(event)) {
 		err = PTR_ERR(event);
 		goto err;
@@ -8163,7 +8140,7 @@ inherit_event(struct perf_event *parent_event,
 					   parent_event->cpu,
 					   child,
 					   group_leader, parent_event,
-				           NULL, NULL);
+					   NULL, NULL, -1);
 	if (IS_ERR(child_event))
 		return child_event;
 

kernel/events/hw_breakpoint.c

@@ -116,12 +116,12 @@ static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type)
  */
 static int task_bp_pinned(int cpu, struct perf_event *bp, enum bp_type_idx type)
 {
-	struct task_struct *tsk = bp->hw.bp_target;
+	struct task_struct *tsk = bp->hw.target;
 	struct perf_event *iter;
 	int count = 0;
 
 	list_for_each_entry(iter, &bp_task_head, hw.bp_list) {
-		if (iter->hw.bp_target == tsk &&
+		if (iter->hw.target == tsk &&
 		    find_slot_idx(iter) == type &&
 		    (iter->cpu < 0 || cpu == iter->cpu))
 			count += hw_breakpoint_weight(iter);
@@ -153,7 +153,7 @@ fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp,
 		int nr;
 
 		nr = info->cpu_pinned;
-		if (!bp->hw.bp_target)
+		if (!bp->hw.target)
 			nr += max_task_bp_pinned(cpu, type);
 		else
 			nr += task_bp_pinned(cpu, bp, type);
@@ -210,7 +210,7 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
 		weight = -weight;
 
 	/* Pinned counter cpu profiling */
-	if (!bp->hw.bp_target) {
+	if (!bp->hw.target) {
 		get_bp_info(bp->cpu, type)->cpu_pinned += weight;
 		return;
 	}

kernel/trace/trace_uprobe.c

@@ -1005,7 +1005,7 @@ __uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm)
 		return true;
 
 	list_for_each_entry(event, &filter->perf_events, hw.tp_list) {
-		if (event->hw.tp_target->mm == mm)
+		if (event->hw.target->mm == mm)
 			return true;
 	}
 
@@ -1015,7 +1015,7 @@ __uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm)
 static inline bool
 uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event)
 {
-	return __uprobe_perf_filter(&tu->filter, event->hw.tp_target->mm);
+	return __uprobe_perf_filter(&tu->filter, event->hw.target->mm);
 }
 
 static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
@@ -1023,10 +1023,10 @@ static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
 	bool done;
 
 	write_lock(&tu->filter.rwlock);
-	if (event->hw.tp_target) {
+	if (event->hw.target) {
 		list_del(&event->hw.tp_list);
 		done = tu->filter.nr_systemwide ||
-			(event->hw.tp_target->flags & PF_EXITING) ||
+			(event->hw.target->flags & PF_EXITING) ||
 			uprobe_filter_event(tu, event);
 	} else {
 		tu->filter.nr_systemwide--;
@@ -1046,7 +1046,7 @@ static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
 	int err;
 
 	write_lock(&tu->filter.rwlock);
-	if (event->hw.tp_target) {
+	if (event->hw.target) {
 		/*
 		 * event->parent != NULL means copy_process(), we can avoid
 		 * uprobe_apply(). current->mm must be probed and we can rely