From cbb72a3c19eff0ea3ccb0b068eca189063c86174 Mon Sep 17 00:00:00 2001 From: Hoan Tran Date: Wed, 7 Nov 2018 19:40:58 +0000 Subject: [PATCH] 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 Signed-off-by: Hoan Tran [will: Made naming of new cpuhp_state enum entry consistent] Signed-off-by: Will Deacon --- drivers/perf/xgene_pmu.c | 80 ++++++++++++++++++++++++++++++++++---- include/linux/cpuhotplug.h | 1 + 2 files changed, 74 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 #include +#include #include #include #include @@ -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; } diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index e0cd2baa8380..d007a319dfd4 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -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,