From 176cda0619b6c17a553625f6e2fcbc3981ad667d Mon Sep 17 00:00:00 2001 From: Kajol Jain Date: Mon, 18 Nov 2024 17:11:11 +0530 Subject: [PATCH] powerpc/perf: Add perf interface to expose vpa counters To support performance measurement for KVM on PowerVM(KoP) feature, PowerVM hypervisor has added couple of new software counters in Virtual Process Area(VPA) of the partition. Commit e1f288d2f9c69 ("KVM: PPC: Book3S HV nestedv2: Add support for reading VPA counters for pseries guests") have updated the paca fields with corresponding changes. Proposed perf interface is to expose these new software counters for monitoring of context switch latencies and runtime aggregate. Perf interface driver is called "vpa_pmu" and it has dependency on KVM and perf, hence added new config called "VPA_PMU" which depends on "CONFIG_KVM_BOOK3S_64_HV" and "CONFIG_HV_PERF_CTRS". Since, kvm and kvm_host are currently compiled as built-in modules, this perf interface takes the same path and registered as a module. vpa_pmu perf interface needs access to some of the kvm functions and structures like kvmhv_get_l2_counters_status(), hence kvm_book3s_64.h and kvm_ppc.h are included. Below are the events added to monitor KoP: vpa_pmu/l1_to_l2_lat/ vpa_pmu/l2_to_l1_lat/ vpa_pmu/l2_runtime_agg/ and vpa_pmu driver supports only per-cpu monitoring with this patch. Example usage: [command]# perf stat -e vpa_pmu/l1_to_l2_lat/ -a -I 1000 1.001017682 727,200 vpa_pmu/l1_to_l2_lat/ 2.003540491 1,118,824 vpa_pmu/l1_to_l2_lat/ 3.005699458 1,919,726 vpa_pmu/l1_to_l2_lat/ 4.007827011 2,364,630 vpa_pmu/l1_to_l2_lat/ Signed-off-by: Kajol Jain Co-developed-by: Madhavan Srinivasan Signed-off-by: Madhavan Srinivasan Signed-off-by: Michael Ellerman Link: https://patch.msgid.link/20241118114114.208964-1-kjain@linux.ibm.com --- arch/powerpc/include/asm/kvm_book3s_64.h | 3 + arch/powerpc/kvm/book3s_hv.c | 19 +++ arch/powerpc/perf/Makefile | 2 + arch/powerpc/perf/vpa-pmu.c | 194 +++++++++++++++++++++++ arch/powerpc/platforms/pseries/Kconfig | 14 ++ 5 files changed, 232 insertions(+) create mode 100644 arch/powerpc/perf/vpa-pmu.c diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h index 11065313d4c12..f620e3126d688 100644 --- a/arch/powerpc/include/asm/kvm_book3s_64.h +++ b/arch/powerpc/include/asm/kvm_book3s_64.h @@ -688,6 +688,9 @@ int kvmhv_counters_tracepoint_regfunc(void); void kvmhv_counters_tracepoint_unregfunc(void); int kvmhv_get_l2_counters_status(void); void kvmhv_set_l2_counters_status(int cpu, bool status); +u64 kvmhv_get_l1_to_l2_cs_time(void); +u64 kvmhv_get_l2_to_l1_cs_time(void); +u64 kvmhv_get_l2_runtime_agg(void); #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index febb9c433f642..4843063df88cc 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -4129,6 +4129,7 @@ void kvmhv_set_l2_counters_status(int cpu, bool status) else lppaca_of(cpu).l2_counters_enable = 0; } +EXPORT_SYMBOL(kvmhv_set_l2_counters_status); int kvmhv_counters_tracepoint_regfunc(void) { @@ -4168,6 +4169,24 @@ static void do_trace_nested_cs_time(struct kvm_vcpu *vcpu) *l2_runtime_agg_ptr = l2_runtime_ns; } +u64 kvmhv_get_l1_to_l2_cs_time(void) +{ + return tb_to_ns(be64_to_cpu(get_lppaca()->l1_to_l2_cs_tb)); +} +EXPORT_SYMBOL(kvmhv_get_l1_to_l2_cs_time); + +u64 kvmhv_get_l2_to_l1_cs_time(void) +{ + return tb_to_ns(be64_to_cpu(get_lppaca()->l2_to_l1_cs_tb)); +} +EXPORT_SYMBOL(kvmhv_get_l2_to_l1_cs_time); + +u64 kvmhv_get_l2_runtime_agg(void) +{ + return tb_to_ns(be64_to_cpu(get_lppaca()->l2_runtime_tb)); +} +EXPORT_SYMBOL(kvmhv_get_l2_runtime_agg); + #else int kvmhv_get_l2_counters_status(void) { diff --git a/arch/powerpc/perf/Makefile b/arch/powerpc/perf/Makefile index 4f53d0b97539b..ac2cf58d62dbb 100644 --- a/arch/powerpc/perf/Makefile +++ b/arch/powerpc/perf/Makefile @@ -16,6 +16,8 @@ obj-$(CONFIG_FSL_EMB_PERF_EVENT_E500) += e500-pmu.o e6500-pmu.o obj-$(CONFIG_HV_PERF_CTRS) += hv-24x7.o hv-gpci.o hv-common.o +obj-$(CONFIG_VPA_PMU) += vpa-pmu.o + obj-$(CONFIG_PPC_8xx) += 8xx-pmu.o obj-$(CONFIG_PPC64) += $(obj64-y) diff --git a/arch/powerpc/perf/vpa-pmu.c b/arch/powerpc/perf/vpa-pmu.c new file mode 100644 index 0000000000000..c143c626b4a02 --- /dev/null +++ b/arch/powerpc/perf/vpa-pmu.c @@ -0,0 +1,194 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Performance monitoring support for Virtual Processor Area(VPA) based counters + * + * Copyright (C) 2024 IBM Corporation + */ +#define pr_fmt(fmt) "vpa_pmu: " fmt + +#include +#include +#include +#include + +#define MODULE_VERS "1.0" +#define MODULE_NAME "pseries_vpa_pmu" + +#define EVENT(_name, _code) enum{_name = _code} + +#define VPA_PMU_EVENT_VAR(_id) event_attr_##_id +#define VPA_PMU_EVENT_PTR(_id) (&event_attr_##_id.attr.attr) + +static ssize_t vpa_pmu_events_sysfs_show(struct device *dev, + struct device_attribute *attr, char *page) +{ + struct perf_pmu_events_attr *pmu_attr; + + pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr); + + return sprintf(page, "event=0x%02llx\n", pmu_attr->id); +} + +#define VPA_PMU_EVENT_ATTR(_name, _id) \ + PMU_EVENT_ATTR(_name, VPA_PMU_EVENT_VAR(_id), _id, \ + vpa_pmu_events_sysfs_show) + +EVENT(L1_TO_L2_CS_LAT, 0x1); +EVENT(L2_TO_L1_CS_LAT, 0x2); +EVENT(L2_RUNTIME_AGG, 0x3); + +VPA_PMU_EVENT_ATTR(l1_to_l2_lat, L1_TO_L2_CS_LAT); +VPA_PMU_EVENT_ATTR(l2_to_l1_lat, L2_TO_L1_CS_LAT); +VPA_PMU_EVENT_ATTR(l2_runtime_agg, L2_RUNTIME_AGG); + +static struct attribute *vpa_pmu_events_attr[] = { + VPA_PMU_EVENT_PTR(L1_TO_L2_CS_LAT), + VPA_PMU_EVENT_PTR(L2_TO_L1_CS_LAT), + VPA_PMU_EVENT_PTR(L2_RUNTIME_AGG), + NULL +}; + +static const struct attribute_group vpa_pmu_events_group = { + .name = "events", + .attrs = vpa_pmu_events_attr, +}; + +PMU_FORMAT_ATTR(event, "config:0-31"); +static struct attribute *vpa_pmu_format_attr[] = { + &format_attr_event.attr, + NULL, +}; + +static struct attribute_group vpa_pmu_format_group = { + .name = "format", + .attrs = vpa_pmu_format_attr, +}; + +static const struct attribute_group *vpa_pmu_attr_groups[] = { + &vpa_pmu_events_group, + &vpa_pmu_format_group, + NULL +}; + +static int vpa_pmu_event_init(struct perf_event *event) +{ + if (event->attr.type != event->pmu->type) + return -ENOENT; + + /* it does not support event sampling mode */ + if (is_sampling_event(event)) + return -EOPNOTSUPP; + + /* no branch sampling */ + if (has_branch_stack(event)) + return -EOPNOTSUPP; + + /* Invalid event code */ + if ((event->attr.config <= 0) || (event->attr.config > 3)) + return -EINVAL; + + return 0; +} + +static unsigned long get_counter_data(struct perf_event *event) +{ + unsigned int config = event->attr.config; + u64 data; + + switch (config) { + case L1_TO_L2_CS_LAT: + data = kvmhv_get_l1_to_l2_cs_time(); + break; + case L2_TO_L1_CS_LAT: + data = kvmhv_get_l2_to_l1_cs_time(); + break; + case L2_RUNTIME_AGG: + data = kvmhv_get_l2_runtime_agg(); + break; + default: + data = 0; + break; + } + + return data; +} + +static int vpa_pmu_add(struct perf_event *event, int flags) +{ + u64 data; + + kvmhv_set_l2_counters_status(smp_processor_id(), true); + + data = get_counter_data(event); + local64_set(&event->hw.prev_count, data); + + return 0; +} + +static void vpa_pmu_read(struct perf_event *event) +{ + u64 prev_data, new_data, final_data; + + prev_data = local64_read(&event->hw.prev_count); + new_data = get_counter_data(event); + final_data = new_data - prev_data; + + local64_add(final_data, &event->count); +} + +static void vpa_pmu_del(struct perf_event *event, int flags) +{ + vpa_pmu_read(event); + + /* + * Disable vpa counter accumulation + */ + kvmhv_set_l2_counters_status(smp_processor_id(), false); +} + +static struct pmu vpa_pmu = { + .task_ctx_nr = perf_sw_context, + .name = "vpa_pmu", + .event_init = vpa_pmu_event_init, + .add = vpa_pmu_add, + .del = vpa_pmu_del, + .read = vpa_pmu_read, + .attr_groups = vpa_pmu_attr_groups, + .capabilities = PERF_PMU_CAP_NO_EXCLUDE | PERF_PMU_CAP_NO_INTERRUPT, +}; + +static int __init pseries_vpa_pmu_init(void) +{ + /* + * List of current Linux on Power platforms and + * this driver is supported only in PowerVM LPAR + * (L1) platform. + * + * Enabled Linux on Power Platforms + * ---------------------------------------- + * [X] PowerVM LPAR (L1) + * [ ] KVM Guest On PowerVM KoP(L2) + * [ ] Baremetal(PowerNV) + * [ ] KVM Guest On PowerNV + */ + if (!firmware_has_feature(FW_FEATURE_LPAR) || is_kvm_guest()) + return -ENODEV; + + perf_pmu_register(&vpa_pmu, vpa_pmu.name, -1); + pr_info("Virtual Processor Area PMU registered.\n"); + + return 0; +} + +static void __exit pseries_vpa_pmu_cleanup(void) +{ + perf_pmu_unregister(&vpa_pmu); + pr_info("Virtual Processor Area PMU unregistered.\n"); +} + +module_init(pseries_vpa_pmu_init); +module_exit(pseries_vpa_pmu_cleanup); +MODULE_DESCRIPTION("Perf Driver for pSeries VPA pmu counter"); +MODULE_AUTHOR("Kajol Jain "); +MODULE_AUTHOR("Madhavan Srinivasan "); +MODULE_LICENSE("GPL"); diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig index afc0f6a613372..42fc66e97539b 100644 --- a/arch/powerpc/platforms/pseries/Kconfig +++ b/arch/powerpc/platforms/pseries/Kconfig @@ -140,6 +140,20 @@ config HV_PERF_CTRS If unsure, select Y. +config VPA_PMU + tristate "VPA PMU events" + depends on KVM_BOOK3S_64_HV && HV_PERF_CTRS + help + Enable access to the VPA PMU counters via perf. This enables + code that support measurement for KVM on PowerVM(KoP) feature. + PAPR hypervisor has introduced three new counters in the VPA area + of LPAR CPUs for KVM L2 guest observability. Two for context switches + from host to guest and vice versa, and one counter for getting + the total time spent inside the KVM guest. This config enables code + that access these software counters via perf. + + If unsure, Select N. + config IBMVIO depends on PPC_PSERIES bool