KVM: Expose a version 2 architectural PMU to a guests

Use perf_events to emulate an architectural PMU, version 2.

Based on PMU version 1 emulation by Avi Kivity.

[avi: adjust for cpuid.c]
[jan: fix anonymous field initialization for older gcc]

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 533 insertions, 0 deletions

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
new file mode 100644
index 000000000000..7aad5446f393
--- /dev/null
+++ b/arch/x86/kvm/pmu.c
@@ -0,0 +1,533 @@
+/*
+ * 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);
+	}
+}