perf/x86/uncore: Support per PMU cpumask

The cpumask of some uncore units, e.g., CXL uncore units, may be wrong
under some configurations. Perf may access an uncore counter of a
non-existent uncore unit.

The uncore driver assumes that all uncore units are symmetric among
dies. A global cpumask is shared among all uncore PMUs. However, some
CXL uncore units may only be available on some dies.

A per PMU cpumask is introduced to track the CPU mask of this PMU.
The driver searches the unit control RB tree to check whether the PMU is
available on a given die, and updates the per PMU cpumask accordingly.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Yunying Sun <yunying.sun@intel.com>
Link: https://lore.kernel.org/r/20240614134631.1092359-3-kan.liang@linux.intel.com

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 419c517b8594fbdd057a0f36bc707c8b6cd8b58f..f699606cf5fcd45971bba745ab8b7bb38f953b3b 100644 (file)
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -843,7 +843,9 @@ static void uncore_pmu_disable(struct pmu *pmu)
 static ssize_t uncore_get_attr_cpumask(struct device *dev,
                                struct device_attribute *attr, char *buf)
 {
-       return cpumap_print_to_pagebuf(true, buf, &uncore_cpu_mask);
+       struct intel_uncore_pmu *pmu = container_of(dev_get_drvdata(dev), struct intel_uncore_pmu, pmu);
+
+       return cpumap_print_to_pagebuf(true, buf, &pmu->cpu_mask);
 }
 
 static DEVICE_ATTR(cpumask, S_IRUGO, uncore_get_attr_cpumask, NULL);
@@ -1453,6 +1455,18 @@ static void uncore_pci_exit(void)
        }
 }
 
+static bool uncore_die_has_box(struct intel_uncore_type *type,
+                              int die, unsigned int pmu_idx)
+{
+       if (!type->boxes)
+               return true;
+
+       if (intel_uncore_find_discovery_unit_id(type->boxes, die, pmu_idx) < 0)
+               return false;
+
+       return true;
+}
+
 static void uncore_change_type_ctx(struct intel_uncore_type *type, int old_cpu,
                                   int new_cpu)
 {
@@ -1468,18 +1482,25 @@ static void uncore_change_type_ctx(struct intel_uncore_type *type, int old_cpu,
 
                if (old_cpu < 0) {
                        WARN_ON_ONCE(box->cpu != -1);
-                       box->cpu = new_cpu;
+                       if (uncore_die_has_box(type, die, pmu->pmu_idx)) {
+                               box->cpu = new_cpu;
+                               cpumask_set_cpu(new_cpu, &pmu->cpu_mask);
+                       }
                        continue;
                }
 
-               WARN_ON_ONCE(box->cpu != old_cpu);
+               WARN_ON_ONCE(box->cpu != -1 && box->cpu != old_cpu);
                box->cpu = -1;
+               cpumask_clear_cpu(old_cpu, &pmu->cpu_mask);
                if (new_cpu < 0)
                        continue;
 
+               if (!uncore_die_has_box(type, die, pmu->pmu_idx))
+                       continue;
                uncore_pmu_cancel_hrtimer(box);
                perf_pmu_migrate_context(&pmu->pmu, old_cpu, new_cpu);
                box->cpu = new_cpu;
+               cpumask_set_cpu(new_cpu, &pmu->cpu_mask);
        }
 }
 
@@ -1502,7 +1523,7 @@ static void uncore_box_unref(struct intel_uncore_type **types, int id)
                pmu = type->pmus;
                for (i = 0; i < type->num_boxes; i++, pmu++) {
                        box = pmu->boxes[id];
-                       if (box && atomic_dec_return(&box->refcnt) == 0)
+                       if (box && box->cpu >= 0 && atomic_dec_return(&box->refcnt) == 0)
                                uncore_box_exit(box);
                }
        }
@@ -1592,7 +1613,7 @@ static int uncore_box_ref(struct intel_uncore_type **types,
                pmu = type->pmus;
                for (i = 0; i < type->num_boxes; i++, pmu++) {
                        box = pmu->boxes[id];
-                       if (box && atomic_inc_return(&box->refcnt) == 1)
+                       if (box && box->cpu >= 0 && atomic_inc_return(&box->refcnt) == 1)
                                uncore_box_init(box);
                }
        }

diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
index 4838502d89aed34dbedf07211322eb3abb3ff59c..0a49e304fe40b121ab2252988671a14e22e2930f 100644 (file)
--- a/arch/x86/events/intel/uncore.h
+++ b/arch/x86/events/intel/uncore.h
@@ -86,6 +86,7 @@ struct intel_uncore_type {
        const struct attribute_group *attr_groups[4];
        const struct attribute_group **attr_update;
        struct pmu *pmu; /* for custom pmu ops */
+       struct rb_root *boxes;
        /*
         * Uncore PMU would store relevant platform topology configuration here
         * to identify which platform component each PMON block of that type is
@@ -125,6 +126,7 @@ struct intel_uncore_pmu {
        int                             func_id;
        bool                            registered;
        atomic_t                        activeboxes;
+       cpumask_t                       cpu_mask;
        struct intel_uncore_type        *type;
        struct intel_uncore_box         **boxes;
 };

diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
index ce520e69a3c1fbede3fc6ed0bab0d89df3156e00..e61e460520a86702a03ee44782775d32d87b5873 100644 (file)
--- a/arch/x86/events/intel/uncore_discovery.c
+++ b/arch/x86/events/intel/uncore_discovery.c
@@ -122,6 +122,64 @@ get_uncore_discovery_type(struct uncore_unit_discovery *unit)
        return add_uncore_discovery_type(unit);
 }
 
+static inline int pmu_idx_cmp(const void *key, const struct rb_node *b)
+{
+       struct intel_uncore_discovery_unit *unit;
+       const unsigned int *id = key;
+
+       unit = rb_entry(b, struct intel_uncore_discovery_unit, node);
+
+       if (unit->pmu_idx > *id)
+               return -1;
+       else if (unit->pmu_idx < *id)
+               return 1;
+
+       return 0;
+}
+
+static struct intel_uncore_discovery_unit *
+intel_uncore_find_discovery_unit(struct rb_root *units, int die,
+                                unsigned int pmu_idx)
+{
+       struct intel_uncore_discovery_unit *unit;
+       struct rb_node *pos;
+
+       if (!units)
+               return NULL;
+
+       pos = rb_find_first(&pmu_idx, units, pmu_idx_cmp);
+       if (!pos)
+               return NULL;
+       unit = rb_entry(pos, struct intel_uncore_discovery_unit, node);
+
+       if (die < 0)
+               return unit;
+
+       for (; pos; pos = rb_next(pos)) {
+               unit = rb_entry(pos, struct intel_uncore_discovery_unit, node);
+
+               if (unit->pmu_idx != pmu_idx)
+                       break;
+
+               if (unit->die == die)
+                       return unit;
+       }
+
+       return NULL;
+}
+
+int intel_uncore_find_discovery_unit_id(struct rb_root *units, int die,
+                                       unsigned int pmu_idx)
+{
+       struct intel_uncore_discovery_unit *unit;
+
+       unit = intel_uncore_find_discovery_unit(units, die, pmu_idx);
+       if (unit)
+               return unit->id;
+
+       return -1;
+}
+
 static inline bool unit_less(struct rb_node *a, const struct rb_node *b)
 {
        struct intel_uncore_discovery_unit *a_node, *b_node;

diff --git a/arch/x86/events/intel/uncore_discovery.h b/arch/x86/events/intel/uncore_discovery.h
index 5190017aba5122b016434e49b56aed2bafa1b721..96265cf1fc864542b84f624a234699d0f842c03e 100644 (file)
--- a/arch/x86/events/intel/uncore_discovery.h
+++ b/arch/x86/events/intel/uncore_discovery.h
@@ -166,3 +166,6 @@ u64 intel_generic_uncore_pci_read_counter(struct intel_uncore_box *box,
 
 struct intel_uncore_type **
 intel_uncore_generic_init_uncores(enum uncore_access_type type_id, int num_extra);
+
+int intel_uncore_find_discovery_unit_id(struct rb_root *units, int die,
+                                       unsigned int pmu_idx);