--- /dev/null
+/*
+ * 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);
projects / cascardo / linux.git / commitdiff