diff options
Diffstat (limited to 'arch/x86/kernel/cpu/perf_event_intel_cqm.c')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event_intel_cqm.c | 1379 |
1 files changed, 1379 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_intel_cqm.c b/arch/x86/kernel/cpu/perf_event_intel_cqm.c new file mode 100644 index 000000000000..e4d1b8b738fa --- /dev/null +++ b/arch/x86/kernel/cpu/perf_event_intel_cqm.c @@ -0,0 +1,1379 @@ +/* + * 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); |