pmu.c

/*
 * Kernel-based Virtual Machine -- Performane Monitoring Unit support
 *
 * Copyright 2011 Red Hat, Inc. and/or its affiliates.
 *
 * Authors:
 *   Avi Kivity   <avi@redhat.com>
 *   Gleb Natapov <gleb@redhat.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 *
 */

#include <linux/types.h>
#include <linux/kvm_host.h>
#include <linux/perf_event.h>
#include "x86.h"
#include "cpuid.h"
#include "lapic.h"

static struct kvm_arch_event_perf_mapping {
	u8 eventsel;
	u8 unit_mask;
	unsigned event_type;
	bool inexact;
} arch_events[] = {
	/* Index must match CPUID 0x0A.EBX bit vector */
	[0] = { 0x3c, 0x00, PERF_COUNT_HW_CPU_CYCLES },
	[1] = { 0xc0, 0x00, PERF_COUNT_HW_INSTRUCTIONS },
	[2] = { 0x3c, 0x01, PERF_COUNT_HW_BUS_CYCLES  },
	[3] = { 0x2e, 0x4f, PERF_COUNT_HW_CACHE_REFERENCES },
	[4] = { 0x2e, 0x41, PERF_COUNT_HW_CACHE_MISSES },
	[5] = { 0xc4, 0x00, PERF_COUNT_HW_BRANCH_INSTRUCTIONS },
	[6] = { 0xc5, 0x00, PERF_COUNT_HW_BRANCH_MISSES },
};

/* mapping between fixed pmc index and arch_events array */
int fixed_pmc_events[] = {1, 0, 2};

static bool pmc_is_gp(struct kvm_pmc *pmc)
{
	return pmc->type == KVM_PMC_GP;
}

static inline u64 pmc_bitmask(struct kvm_pmc *pmc)
{
	struct kvm_pmu *pmu = &pmc->vcpu->arch.pmu;

	return pmu->counter_bitmask[pmc->type];
}

static inline bool pmc_enabled(struct kvm_pmc *pmc)
{
	struct kvm_pmu *pmu = &pmc->vcpu->arch.pmu;
	return test_bit(pmc->idx, (unsigned long *)&pmu->global_ctrl);
}

static inline struct kvm_pmc *get_gp_pmc(struct kvm_pmu *pmu, u32 msr,
					 u32 base)
{
	if (msr >= base && msr < base + pmu->nr_arch_gp_counters)
		return &pmu->gp_counters[msr - base];
	return NULL;
}

static inline struct kvm_pmc *get_fixed_pmc(struct kvm_pmu *pmu, u32 msr)
{
	int base = MSR_CORE_PERF_FIXED_CTR0;
	if (msr >= base && msr < base + pmu->nr_arch_fixed_counters)
		return &pmu->fixed_counters[msr - base];
	return NULL;
}

static inline struct kvm_pmc *get_fixed_pmc_idx(struct kvm_pmu *pmu, int idx)
{
	return get_fixed_pmc(pmu, MSR_CORE_PERF_FIXED_CTR0 + idx);
}

static struct kvm_pmc *global_idx_to_pmc(struct kvm_pmu *pmu, int idx)
{
	if (idx < X86_PMC_IDX_FIXED)
		return get_gp_pmc(pmu, MSR_P6_EVNTSEL0 + idx, MSR_P6_EVNTSEL0);
	else
		return get_fixed_pmc_idx(pmu, idx - X86_PMC_IDX_FIXED);
}

void kvm_deliver_pmi(struct kvm_vcpu *vcpu)
{
	if (vcpu->arch.apic)
		kvm_apic_local_deliver(vcpu->arch.apic, APIC_LVTPC);
}

static void trigger_pmi(struct irq_work *irq_work)
{
	struct kvm_pmu *pmu = container_of(irq_work, struct kvm_pmu,
			irq_work);
	struct kvm_vcpu *vcpu = container_of(pmu, struct kvm_vcpu,
			arch.pmu);

	kvm_deliver_pmi(vcpu);
}

static void kvm_perf_overflow(struct perf_event *perf_event,
			      struct perf_sample_data *data,
			      struct pt_regs *regs)
{
	struct kvm_pmc *pmc = perf_event->overflow_handler_context;
	struct kvm_pmu *pmu = &pmc->vcpu->arch.pmu;
	__set_bit(pmc->idx, (unsigned long *)&pmu->global_status);
}

static void kvm_perf_overflow_intr(struct perf_event *perf_event,
		struct perf_sample_data *data, struct pt_regs *regs)
{
	struct kvm_pmc *pmc = perf_event->overflow_handler_context;
	struct kvm_pmu *pmu = &pmc->vcpu->arch.pmu;
	if (!test_and_set_bit(pmc->idx, (unsigned long *)&pmu->reprogram_pmi)) {
		kvm_perf_overflow(perf_event, data, regs);
		kvm_make_request(KVM_REQ_PMU, pmc->vcpu);
		/*
		 * Inject PMI. If vcpu was in a guest mode during NMI PMI
		 * can be ejected on a guest mode re-entry. Otherwise we can't
		 * be sure that vcpu wasn't executing hlt instruction at the
		 * time of vmexit and is not going to re-enter guest mode until,
		 * woken up. So we should wake it, but this is impossible from
		 * NMI context. Do it from irq work instead.
		 */
		if (!kvm_is_in_guest())
			irq_work_queue(&pmc->vcpu->arch.pmu.irq_work);
		else
			kvm_make_request(KVM_REQ_PMI, pmc->vcpu);
	}
}

static u64 read_pmc(struct kvm_pmc *pmc)
{
	u64 counter, enabled, running;

	counter = pmc->counter;

	if (pmc->perf_event)
		counter += perf_event_read_value(pmc->perf_event,
						 &enabled, &running);

	/* FIXME: Scaling needed? */

	return counter & pmc_bitmask(pmc);
}

static void stop_counter(struct kvm_pmc *pmc)
{
	if (pmc->perf_event) {
		pmc->counter = read_pmc(pmc);
		perf_event_release_kernel(pmc->perf_event);
		pmc->perf_event = NULL;
	}
}

static void reprogram_counter(struct kvm_pmc *pmc, u32 type,
		unsigned config, bool exclude_user, bool exclude_kernel,
		bool intr)
{
	struct perf_event *event;
	struct perf_event_attr attr = {
		.type = type,
		.size = sizeof(attr),
		.pinned = true,
		.exclude_idle = true,
		.exclude_host = 1,
		.exclude_user = exclude_user,
		.exclude_kernel = exclude_kernel,
		.config = config,
	};

	attr.sample_period = (-pmc->counter) & pmc_bitmask(pmc);

	event = perf_event_create_kernel_counter(&attr, -1, current,
						 intr ? kvm_perf_overflow_intr :
						 kvm_perf_overflow, pmc);
	if (IS_ERR(event)) {
		printk_once("kvm: pmu event creation failed %ld\n",
				PTR_ERR(event));
		return;
	}

	pmc->perf_event = event;
	clear_bit(pmc->idx, (unsigned long*)&pmc->vcpu->arch.pmu.reprogram_pmi);
}

static unsigned find_arch_event(struct kvm_pmu *pmu, u8 event_select,
		u8 unit_mask)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(arch_events); i++)
		if (arch_events[i].eventsel == event_select
				&& arch_events[i].unit_mask == unit_mask
				&& (pmu->available_event_types & (1 << i)))
			break;

	if (i == ARRAY_SIZE(arch_events))
		return PERF_COUNT_HW_MAX;

	return arch_events[i].event_type;
}

static void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)
{
	unsigned config, type = PERF_TYPE_RAW;
	u8 event_select, unit_mask;

	pmc->eventsel = eventsel;

	stop_counter(pmc);

	if (!(eventsel & ARCH_PERFMON_EVENTSEL_ENABLE) || !pmc_enabled(pmc))
		return;

	event_select = eventsel & ARCH_PERFMON_EVENTSEL_EVENT;
	unit_mask = (eventsel & ARCH_PERFMON_EVENTSEL_UMASK) >> 8;

	if (!(event_select & (ARCH_PERFMON_EVENTSEL_EDGE |
				ARCH_PERFMON_EVENTSEL_INV |
				ARCH_PERFMON_EVENTSEL_CMASK))) {
		config = find_arch_event(&pmc->vcpu->arch.pmu, event_select,
				unit_mask);
		if (config != PERF_COUNT_HW_MAX)
			type = PERF_TYPE_HARDWARE;
	}

	if (type == PERF_TYPE_RAW)
		config = eventsel & X86_RAW_EVENT_MASK;

	reprogram_counter(pmc, type, config,
			!(eventsel & ARCH_PERFMON_EVENTSEL_USR),
			!(eventsel & ARCH_PERFMON_EVENTSEL_OS),
			eventsel & ARCH_PERFMON_EVENTSEL_INT);
}

static void reprogram_fixed_counter(struct kvm_pmc *pmc, u8 en_pmi, int idx)
{
	unsigned en = en_pmi & 0x3;
	bool pmi = en_pmi & 0x8;

	stop_counter(pmc);

	if (!en || !pmc_enabled(pmc))
		return;

	reprogram_counter(pmc, PERF_TYPE_HARDWARE,
			arch_events[fixed_pmc_events[idx]].event_type,
			!(en & 0x2), /* exclude user */
			!(en & 0x1), /* exclude kernel */
			pmi);
}

static inline u8 fixed_en_pmi(u64 ctrl, int idx)
{
	return (ctrl >> (idx * 4)) & 0xf;
}

static void reprogram_fixed_counters(struct kvm_pmu *pmu, u64 data)
{
	int i;

	for (i = 0; i < pmu->nr_arch_fixed_counters; i++) {
		u8 en_pmi = fixed_en_pmi(data, i);
		struct kvm_pmc *pmc = get_fixed_pmc_idx(pmu, i);

		if (fixed_en_pmi(pmu->fixed_ctr_ctrl, i) == en_pmi)
			continue;

		reprogram_fixed_counter(pmc, en_pmi, i);
	}

	pmu->fixed_ctr_ctrl = data;
}

static void reprogram_idx(struct kvm_pmu *pmu, int idx)
{
	struct kvm_pmc *pmc = global_idx_to_pmc(pmu, idx);

	if (!pmc)
		return;

	if (pmc_is_gp(pmc))
		reprogram_gp_counter(pmc, pmc->eventsel);
	else {
		int fidx = idx - X86_PMC_IDX_FIXED;
		reprogram_fixed_counter(pmc,
				fixed_en_pmi(pmu->fixed_ctr_ctrl, fidx), fidx);
	}
}

static void global_ctrl_changed(struct kvm_pmu *pmu, u64 data)
{
	int bit;
	u64 diff = pmu->global_ctrl ^ data;

	pmu->global_ctrl = data;

	for_each_set_bit(bit, (unsigned long *)&diff, X86_PMC_IDX_MAX)
		reprogram_idx(pmu, bit);
}

bool kvm_pmu_msr(struct kvm_vcpu *vcpu, u32 msr)
{
	struct kvm_pmu *pmu = &vcpu->arch.pmu;
	int ret;

	switch (msr) {
	case MSR_CORE_PERF_FIXED_CTR_CTRL:
	case MSR_CORE_PERF_GLOBAL_STATUS:
	case MSR_CORE_PERF_GLOBAL_CTRL:
	case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
		ret = pmu->version > 1;
		break;
	default:
		ret = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)
			|| get_gp_pmc(pmu, msr, MSR_P6_EVNTSEL0)
			|| get_fixed_pmc(pmu, msr);
		break;
	}
	return ret;
}

int kvm_pmu_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data)
{
	struct kvm_pmu *pmu = &vcpu->arch.pmu;
	struct kvm_pmc *pmc;

	switch (index) {
	case MSR_CORE_PERF_FIXED_CTR_CTRL:
		*data = pmu->fixed_ctr_ctrl;
		return 0;
	case MSR_CORE_PERF_GLOBAL_STATUS:
		*data = pmu->global_status;
		return 0;
	case MSR_CORE_PERF_GLOBAL_CTRL:
		*data = pmu->global_ctrl;
		return 0;
	case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
		*data = pmu->global_ovf_ctrl;
		return 0;
	default:
		if ((pmc = get_gp_pmc(pmu, index, MSR_IA32_PERFCTR0)) ||
				(pmc = get_fixed_pmc(pmu, index))) {
			*data = read_pmc(pmc);
			return 0;
		} else if ((pmc = get_gp_pmc(pmu, index, MSR_P6_EVNTSEL0))) {
			*data = pmc->eventsel;
			return 0;
		}
	}
	return 1;
}

int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, u32 index, u64 data)
{
	struct kvm_pmu *pmu = &vcpu->arch.pmu;
	struct kvm_pmc *pmc;

	switch (index) {
	case MSR_CORE_PERF_FIXED_CTR_CTRL:
		if (pmu->fixed_ctr_ctrl == data)
			return 0;
		if (!(data & 0xfffffffffffff444)) {
			reprogram_fixed_counters(pmu, data);
			return 0;
		}
		break;
	case MSR_CORE_PERF_GLOBAL_STATUS:
		break; /* RO MSR */
	case MSR_CORE_PERF_GLOBAL_CTRL:
		if (pmu->global_ctrl == data)
			return 0;
		if (!(data & pmu->global_ctrl_mask)) {
			global_ctrl_changed(pmu, data);
			return 0;
		}
		break;
	case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
		if (!(data & (pmu->global_ctrl_mask & ~(3ull<<62)))) {
			pmu->global_status &= ~data;
			pmu->global_ovf_ctrl = data;
			return 0;
		}
		break;
	default:
		if ((pmc = get_gp_pmc(pmu, index, MSR_IA32_PERFCTR0)) ||
				(pmc = get_fixed_pmc(pmu, index))) {
			data = (s64)(s32)data;
			pmc->counter += data - read_pmc(pmc);
			return 0;
		} else if ((pmc = get_gp_pmc(pmu, index, MSR_P6_EVNTSEL0))) {
			if (data == pmc->eventsel)
				return 0;
			if (!(data & 0xffffffff00200000ull)) {
				reprogram_gp_counter(pmc, data);
				return 0;
			}
		}
	}
	return 1;
}

int kvm_pmu_read_pmc(struct kvm_vcpu *vcpu, unsigned pmc, u64 *data)
{
	struct kvm_pmu *pmu = &vcpu->arch.pmu;
	bool fast_mode = pmc & (1u << 31);
	bool fixed = pmc & (1u << 30);
	struct kvm_pmc *counters;
	u64 ctr;

	pmc &= (3u << 30) - 1;
	if (!fixed && pmc >= pmu->nr_arch_gp_counters)
		return 1;
	if (fixed && pmc >= pmu->nr_arch_fixed_counters)
		return 1;
	counters = fixed ? pmu->fixed_counters : pmu->gp_counters;
	ctr = read_pmc(&counters[pmc]);
	if (fast_mode)
		ctr = (u32)ctr;
	*data = ctr;

	return 0;
}

void kvm_pmu_cpuid_update(struct kvm_vcpu *vcpu)
{
	struct kvm_pmu *pmu = &vcpu->arch.pmu;
	struct kvm_cpuid_entry2 *entry;
	unsigned bitmap_len;

	pmu->nr_arch_gp_counters = 0;
	pmu->nr_arch_fixed_counters = 0;
	pmu->counter_bitmask[KVM_PMC_GP] = 0;
	pmu->counter_bitmask[KVM_PMC_FIXED] = 0;
	pmu->version = 0;

	entry = kvm_find_cpuid_entry(vcpu, 0xa, 0);
	if (!entry)
		return;

	pmu->version = entry->eax & 0xff;
	if (!pmu->version)
		return;

	pmu->nr_arch_gp_counters = min((int)(entry->eax >> 8) & 0xff,
			X86_PMC_MAX_GENERIC);
	pmu->counter_bitmask[KVM_PMC_GP] =
		((u64)1 << ((entry->eax >> 16) & 0xff)) - 1;
	bitmap_len = (entry->eax >> 24) & 0xff;
	pmu->available_event_types = ~entry->ebx & ((1ull << bitmap_len) - 1);

	if (pmu->version == 1) {
		pmu->global_ctrl = (1 << pmu->nr_arch_gp_counters) - 1;
		return;
	}

	pmu->nr_arch_fixed_counters = min((int)(entry->edx & 0x1f),
			X86_PMC_MAX_FIXED);
	pmu->counter_bitmask[KVM_PMC_FIXED] =
		((u64)1 << ((entry->edx >> 5) & 0xff)) - 1;
	pmu->global_ctrl_mask = ~(((1 << pmu->nr_arch_gp_counters) - 1)
			| (((1ull << pmu->nr_arch_fixed_counters) - 1)
				<< X86_PMC_IDX_FIXED));
}

void kvm_pmu_init(struct kvm_vcpu *vcpu)
{
	int i;
	struct kvm_pmu *pmu = &vcpu->arch.pmu;

	memset(pmu, 0, sizeof(*pmu));
	for (i = 0; i < X86_PMC_MAX_GENERIC; i++) {
		pmu->gp_counters[i].type = KVM_PMC_GP;
		pmu->gp_counters[i].vcpu = vcpu;
		pmu->gp_counters[i].idx = i;
	}
	for (i = 0; i < X86_PMC_MAX_FIXED; i++) {
		pmu->fixed_counters[i].type = KVM_PMC_FIXED;
		pmu->fixed_counters[i].vcpu = vcpu;
		pmu->fixed_counters[i].idx = i + X86_PMC_IDX_FIXED;
	}
	init_irq_work(&pmu->irq_work, trigger_pmi);
	kvm_pmu_cpuid_update(vcpu);
}

void kvm_pmu_reset(struct kvm_vcpu *vcpu)
{
	struct kvm_pmu *pmu = &vcpu->arch.pmu;
	int i;

	irq_work_sync(&pmu->irq_work);
	for (i = 0; i < X86_PMC_MAX_GENERIC; i++) {
		struct kvm_pmc *pmc = &pmu->gp_counters[i];
		stop_counter(pmc);
		pmc->counter = pmc->eventsel = 0;
	}

	for (i = 0; i < X86_PMC_MAX_FIXED; i++)
		stop_counter(&pmu->fixed_counters[i]);

	pmu->fixed_ctr_ctrl = pmu->global_ctrl = pmu->global_status =
		pmu->global_ovf_ctrl = 0;
}

void kvm_pmu_destroy(struct kvm_vcpu *vcpu)
{
	kvm_pmu_reset(vcpu);
}

void kvm_handle_pmu_event(struct kvm_vcpu *vcpu)
{
	struct kvm_pmu *pmu = &vcpu->arch.pmu;
	u64 bitmask;
	int bit;

	bitmask = pmu->reprogram_pmi;

	for_each_set_bit(bit, (unsigned long *)&bitmask, X86_PMC_IDX_MAX) {
		struct kvm_pmc *pmc = global_idx_to_pmc(pmu, bit);

		if (unlikely(!pmc || !pmc->perf_event)) {
			clear_bit(bit, (unsigned long *)&pmu->reprogram_pmi);
			continue;
		}

		reprogram_idx(pmu, bit);
	}
}