powerpc/perf: Add perf interface to expose vpa counters (176cda06) · Commits · git / linux-net

arch/powerpc/include/asm/kvm_book3s_64.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -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 */

arch/powerpc/kvm/book3s_hv.c

+19 −0

Original line number	Diff line number	Diff line
		@@ -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)
		{

arch/powerpc/perf/Makefile

+2 −0

Original line number	Diff line number	Diff line
		@@ -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)

arch/powerpc/perf/vpa-pmu.c

0 → 100644

+194 −0

Original line number	Diff line number	Diff line
		// 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 <linux/module.h>
		#include <linux/perf_event.h>
		#include <asm/kvm_ppc.h>
		#include <asm/kvm_book3s_64.h>

		#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 <kjain@linux.ibm.com>");
		MODULE_AUTHOR("Madhavan Srinivasan <maddy@linux.ibm.com>");
		MODULE_LICENSE("GPL");

arch/powerpc/platforms/pseries/Kconfig

+14 −0

Original line number	Diff line number	Diff line
		@@ -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