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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>
This commit is contained in:
Hoan Tran 2018-11-07 19:40:58 +00:00 committed by Will Deacon
parent 472dc9fa7c
commit cbb72a3c19
2 changed files with 74 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

80
drivers/perf/xgene_pmu.c
View File

@ -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;
}

1
include/linux/cpuhotplug.h
View File

@ -164,6 +164,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_ARM_L2X0_ONLINE,
CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
CPUHP_AP_PERF_ARM_QCOM_L3_ONLINE,
CPUHP_AP_PERF_ARM_APM_XGENE_ONLINE,
CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE,
CPUHP_AP_PERF_POWERPC_CORE_IMC_ONLINE,
CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,