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authorHoan Tran <Hoan@os.amperecomputing.com>2018-11-07 19:40:58 +0000
committerWill Deacon <will.deacon@arm.com>2018-11-21 16:28:00 +0000
commitcbb72a3c19eff0ea3ccb0b068eca189063c86174 (patch)
tree81ca26892c6ba72b7c56b00ebe03c4431973629f /drivers/perf
parent472dc9fa7cc0769321d91b55eed4e21e2ab86632 (diff)
drivers/perf: xgene: Add CPU hotplug support
If the CPU assigned to the xgene PMU is taken offline, then subsequent perf invocations on the PMU will fail: # echo 0 > /sys/devices/system/cpu/cpu0/online # perf stat -a -e l3c0/cycle-count/,l3c0/write/ sleep 1 Error: The sys_perf_event_open() syscall returned with 19 (No such device) for event (l3c0/cycle-count/). /bin/dmesg may provide additional information. No CONFIG_PERF_EVENTS=y kernel support configured? This patch implements a hotplug notifier in the xgene PMU driver so that the PMU context is migrated to another online CPU should its assigned CPU disappear. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Hoan Tran <hoan.tran@amperecomputing.com> [will: Made naming of new cpuhp_state enum entry consistent] Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'drivers/perf')
-rw-r--r--drivers/perf/xgene_pmu.c80
1 files changed, 73 insertions, 7 deletions
diff --git a/drivers/perf/xgene_pmu.c b/drivers/perf/xgene_pmu.c
index 0e31f1392a53..0dc9ff0f8894 100644
--- a/drivers/perf/xgene_pmu.c
+++ b/drivers/perf/xgene_pmu.c
@@ -21,6 +21,7 @@
#include <linux/acpi.h>
#include <linux/clk.h>
+#include <linux/cpuhotplug.h>
#include <linux/cpumask.h>
#include <linux/interrupt.h>
#include <linux/io.h>
@@ -130,12 +131,14 @@ struct xgene_pmu_ops {
struct xgene_pmu {
struct device *dev;
+ struct hlist_node node;
int version;
void __iomem *pcppmu_csr;
u32 mcb_active_mask;
u32 mc_active_mask;
u32 l3c_active_mask;
cpumask_t cpu;
+ int irq;
raw_spinlock_t lock;
const struct xgene_pmu_ops *ops;
struct list_head l3cpmus;
@@ -1806,6 +1809,53 @@ static const struct acpi_device_id xgene_pmu_acpi_match[] = {
MODULE_DEVICE_TABLE(acpi, xgene_pmu_acpi_match);
#endif
+static int xgene_pmu_online_cpu(unsigned int cpu, struct hlist_node *node)
+{
+ struct xgene_pmu *xgene_pmu = hlist_entry_safe(node, struct xgene_pmu,
+ node);
+
+ if (cpumask_empty(&xgene_pmu->cpu))
+ cpumask_set_cpu(cpu, &xgene_pmu->cpu);
+
+ /* Overflow interrupt also should use the same CPU */
+ WARN_ON(irq_set_affinity(xgene_pmu->irq, &xgene_pmu->cpu));
+
+ return 0;
+}
+
+static int xgene_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
+{
+ struct xgene_pmu *xgene_pmu = hlist_entry_safe(node, struct xgene_pmu,
+ node);
+ struct xgene_pmu_dev_ctx *ctx;
+ unsigned int target;
+
+ if (!cpumask_test_and_clear_cpu(cpu, &xgene_pmu->cpu))
+ return 0;
+ target = cpumask_any_but(cpu_online_mask, cpu);
+ if (target >= nr_cpu_ids)
+ return 0;
+
+ list_for_each_entry(ctx, &xgene_pmu->mcpmus, next) {
+ perf_pmu_migrate_context(&ctx->pmu_dev->pmu, cpu, target);
+ }
+ list_for_each_entry(ctx, &xgene_pmu->mcbpmus, next) {
+ perf_pmu_migrate_context(&ctx->pmu_dev->pmu, cpu, target);
+ }
+ list_for_each_entry(ctx, &xgene_pmu->l3cpmus, next) {
+ perf_pmu_migrate_context(&ctx->pmu_dev->pmu, cpu, target);
+ }
+ list_for_each_entry(ctx, &xgene_pmu->iobpmus, next) {
+ perf_pmu_migrate_context(&ctx->pmu_dev->pmu, cpu, target);
+ }
+
+ cpumask_set_cpu(target, &xgene_pmu->cpu);
+ /* Overflow interrupt also should use the same CPU */
+ WARN_ON(irq_set_affinity(xgene_pmu->irq, &xgene_pmu->cpu));
+
+ return 0;
+}
+
static int xgene_pmu_probe(struct platform_device *pdev)
{
const struct xgene_pmu_data *dev_data;
@@ -1815,6 +1865,14 @@ static int xgene_pmu_probe(struct platform_device *pdev)
int irq, rc;
int version;
+ /* Install a hook to update the reader CPU in case it goes offline */
+ rc = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_APM_XGENE_ONLINE,
+ "CPUHP_AP_PERF_ARM_APM_XGENE_ONLINE",
+ xgene_pmu_online_cpu,
+ xgene_pmu_offline_cpu);
+ if (rc)
+ return rc;
+
xgene_pmu = devm_kzalloc(&pdev->dev, sizeof(*xgene_pmu), GFP_KERNEL);
if (!xgene_pmu)
return -ENOMEM;
@@ -1865,6 +1923,7 @@ static int xgene_pmu_probe(struct platform_device *pdev)
dev_err(&pdev->dev, "No IRQ resource\n");
return -EINVAL;
}
+
rc = devm_request_irq(&pdev->dev, irq, xgene_pmu_isr,
IRQF_NOBALANCING | IRQF_NO_THREAD,
dev_name(&pdev->dev), xgene_pmu);
@@ -1873,6 +1932,8 @@ static int xgene_pmu_probe(struct platform_device *pdev)
return rc;
}
+ xgene_pmu->irq = irq;
+
raw_spin_lock_init(&xgene_pmu->lock);
/* Check for active MCBs and MCUs */
@@ -1883,13 +1944,11 @@ static int xgene_pmu_probe(struct platform_device *pdev)
xgene_pmu->mc_active_mask = 0x1;
}
- /* Pick one core to use for cpumask attributes */
- cpumask_set_cpu(smp_processor_id(), &xgene_pmu->cpu);
-
- /* Make sure that the overflow interrupt is handled by this CPU */
- rc = irq_set_affinity(irq, &xgene_pmu->cpu);
+ /* Add this instance to the list used by the hotplug callback */
+ rc = cpuhp_state_add_instance(CPUHP_AP_PERF_ARM_APM_XGENE_ONLINE,
+ &xgene_pmu->node);
if (rc) {
- dev_err(&pdev->dev, "Failed to set interrupt affinity!\n");
+ dev_err(&pdev->dev, "Error %d registering hotplug", rc);
return rc;
}
@@ -1897,13 +1956,18 @@ static int xgene_pmu_probe(struct platform_device *pdev)
rc = xgene_pmu_probe_pmu_dev(xgene_pmu, pdev);
if (rc) {
dev_err(&pdev->dev, "No PMU perf devices found!\n");
- return rc;
+ goto out_unregister;
}
/* Enable interrupt */
xgene_pmu->ops->unmask_int(xgene_pmu);
return 0;
+
+out_unregister:
+ cpuhp_state_remove_instance(CPUHP_AP_PERF_ARM_APM_XGENE_ONLINE,
+ &xgene_pmu->node);
+ return rc;
}
static void
@@ -1924,6 +1988,8 @@ static int xgene_pmu_remove(struct platform_device *pdev)
xgene_pmu_dev_cleanup(xgene_pmu, &xgene_pmu->iobpmus);
xgene_pmu_dev_cleanup(xgene_pmu, &xgene_pmu->mcbpmus);
xgene_pmu_dev_cleanup(xgene_pmu, &xgene_pmu->mcpmus);
+ cpuhp_state_remove_instance(CPUHP_AP_PERF_ARM_APM_XGENE_ONLINE,
+ &xgene_pmu->node);
return 0;
}