[PATCH 2/8] perf/x86/uncore: Support per PMU cpumask

kan.liang
2024-06-10T20:17:52Z

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.

Tested-by: Yunying Sun <yunying.sun@intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
---
arch/x86/events/intel/uncore.c | 31 +++++++++++--
arch/x86/events/intel/uncore.h | 2 +
arch/x86/events/intel/uncore_discovery.c | 58 ++++++++++++++++++++++++
arch/x86/events/intel/uncore_discovery.h | 3 ++
4 files changed, 89 insertions(+), 5 deletions(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index c68f5b39952b..075c92e0e4bc 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -844,7 +844,9 @@ 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);
@@ -1454,6 +1456,18 @@ 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)
{
@@ -1469,18 +1483,25 @@ 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);
}
}

@@ -1503,7 +1524,7 @@ 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);
}
}
@@ -1593,7 +1614,7 @@ 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 4838502d89ae..0a49e304fe40 100644
--- 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 ce520e69a3c1..e61e460520a8 100644
--- 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 5190017aba51..96265cf1fc86 100644
--- 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);
--
2.35.1