// SPDX-License-Identifier: GPL-2.0-only
/*
 * Kernel-based Virtual Machine -- Performance Monitoring Unit support
 *
 * Copyright 2015 Red Hat, Inc. and/or its affiliates.
 *
 * Authors:
 *   Avi Kivity   <avi@redhat.com>
 *   Gleb Natapov <gleb@redhat.com>
 *   Wei Huang    <wei@redhat.com>
 */

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

/* This is enough to filter the vast majority of currently defined events. */
#define KVM_PMU_EVENT_FILTER_MAX_EVENTS 300

/* NOTE:
 * - Each perf counter is defined as "struct kvm_pmc";
 * - There are two types of perf counters: general purpose (gp) and fixed.
 *   gp counters are stored in gp_counters[] and fixed counters are stored
 *   in fixed_counters[] respectively. Both of them are part of "struct
 *   kvm_pmu";
 * - pmu.c understands the difference between gp counters and fixed counters.
 *   However AMD doesn't support fixed-counters;
 * - There are three types of index to access perf counters (PMC):
 *     1. MSR (named msr): For example Intel has MSR_IA32_PERFCTRn and AMD
 *        has MSR_K7_PERFCTRn.
 *     2. MSR Index (named idx): This normally is used by RDPMC instruction.
 *        For instance AMD RDPMC instruction uses 0000_0003h in ECX to access
 *        C001_0007h (MSR_K7_PERCTR3). Intel has a similar mechanism, except
 *        that it also supports fixed counters. idx can be used to as index to
 *        gp and fixed counters.
 *     3. Global PMC Index (named pmc): pmc is an index specific to PMU
 *        code. Each pmc, stored in kvm_pmc.idx field, is unique across
 *        all perf counters (both gp and fixed). The mapping relationship
 *        between pmc and perf counters is as the following:
 *        * Intel: [0 .. INTEL_PMC_MAX_GENERIC-1] <=> gp counters
 *                 [INTEL_PMC_IDX_FIXED .. INTEL_PMC_IDX_FIXED + 2] <=> fixed
 *        * AMD:   [0 .. AMD64_NUM_COUNTERS-1] <=> gp counters
 */

static void kvm_pmi_trigger_fn(struct irq_work *irq_work)
{
        struct kvm_pmu *pmu = container_of(irq_work, struct kvm_pmu, irq_work);
        struct kvm_vcpu *vcpu = pmu_to_vcpu(pmu);

        kvm_pmu_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_to_pmu(pmc);

        if (!test_and_set_bit(pmc->idx, pmu->reprogram_pmi)) {
                __set_bit(pmc->idx, (unsigned long *)&pmu->global_status);
                kvm_make_request(KVM_REQ_PMU, pmc->vcpu);
        }
}

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_to_pmu(pmc);

        if (!test_and_set_bit(pmc->idx, pmu->reprogram_pmi)) {
                __set_bit(pmc->idx, (unsigned long *)&pmu->global_status);
                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_to_pmu(pmc)->irq_work);
                else
                        kvm_make_request(KVM_REQ_PMI, pmc->vcpu);
        }
}

static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
                                  unsigned config, bool exclude_user,
                                  bool exclude_kernel, bool intr,
                                  bool in_tx, bool in_tx_cp)
{
        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 = get_sample_period(pmc, pmc->counter);

        if (in_tx)
                attr.config |= HSW_IN_TX;
        if (in_tx_cp) {
                /*
                 * HSW_IN_TX_CHECKPOINTED is not supported with nonzero
                 * period. Just clear the sample period so at least
                 * allocating the counter doesn't fail.
                 */
                attr.sample_period = 0;
                attr.config |= HSW_IN_TX_CHECKPOINTED;
        }

        event = perf_event_create_kernel_counter(&attr, -1, current,
                                                 intr ? kvm_perf_overflow_intr :
                                                 kvm_perf_overflow, pmc);
        if (IS_ERR(event)) {
                pr_debug_ratelimited("kvm_pmu: event creation failed %ld for pmc->idx = %d\n",
                            PTR_ERR(event), pmc->idx);
                return;
        }

        pmc->perf_event = event;
        pmc_to_pmu(pmc)->event_count++;
        clear_bit(pmc->idx, pmc_to_pmu(pmc)->reprogram_pmi);
        pmc->is_paused = false;
}

static void pmc_pause_counter(struct kvm_pmc *pmc)
{
        u64 counter = pmc->counter;

        if (!pmc->perf_event || pmc->is_paused)
                return;

        /* update counter, reset event value to avoid redundant accumulation */
        counter += perf_event_pause(pmc->perf_event, true);
        pmc->counter = counter & pmc_bitmask(pmc);
        pmc->is_paused = true;
}

static bool pmc_resume_counter(struct kvm_pmc *pmc)
{
        if (!pmc->perf_event)
                return false;

        /* recalibrate sample period and check if it's accepted by perf core */
        if (perf_event_period(pmc->perf_event,
                              get_sample_period(pmc, pmc->counter)))
                return false;

        /* reuse perf_event to serve as pmc_reprogram_counter() does*/
        perf_event_enable(pmc->perf_event);
        pmc->is_paused = false;

        clear_bit(pmc->idx, (unsigned long *)&pmc_to_pmu(pmc)->reprogram_pmi);
        return true;
}

void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)
{
        unsigned config, type = PERF_TYPE_RAW;
        u8 event_select, unit_mask;
        struct kvm *kvm = pmc->vcpu->kvm;
        struct kvm_pmu_event_filter *filter;
        int i;
        bool allow_event = true;

        if (eventsel & ARCH_PERFMON_EVENTSEL_PIN_CONTROL)
                printk_once("kvm pmu: pin control bit is ignored\n");

        pmc->eventsel = eventsel;

        pmc_pause_counter(pmc);

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

        filter = srcu_dereference(kvm->arch.pmu_event_filter, &kvm->srcu);
        if (filter) {
                for (i = 0; i < filter->nevents; i++)
                        if (filter->events[i] ==
                            (eventsel & AMD64_RAW_EVENT_MASK_NB))
                                break;
                if (filter->action == KVM_PMU_EVENT_ALLOW &&
                    i == filter->nevents)
                        allow_event = false;
                if (filter->action == KVM_PMU_EVENT_DENY &&
                    i < filter->nevents)
                        allow_event = false;
        }
        if (!allow_event)
                return;

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

        if (!(eventsel & (ARCH_PERFMON_EVENTSEL_EDGE |
                          ARCH_PERFMON_EVENTSEL_INV |
                          ARCH_PERFMON_EVENTSEL_CMASK |
                          HSW_IN_TX |
                          HSW_IN_TX_CHECKPOINTED))) {
                config = kvm_x86_ops.pmu_ops->find_arch_event(pmc_to_pmu(pmc),
                                                      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;

        if (pmc->current_config == eventsel && pmc_resume_counter(pmc))
                return;

        pmc_release_perf_event(pmc);

        pmc->current_config = eventsel;
        pmc_reprogram_counter(pmc, type, config,
                              !(eventsel & ARCH_PERFMON_EVENTSEL_USR),
                              !(eventsel & ARCH_PERFMON_EVENTSEL_OS),
                              eventsel & ARCH_PERFMON_EVENTSEL_INT,
                              (eventsel & HSW_IN_TX),
                              (eventsel & HSW_IN_TX_CHECKPOINTED));
}
EXPORT_SYMBOL_GPL(reprogram_gp_counter);

void reprogram_fixed_counter(struct kvm_pmc *pmc, u8 ctrl, int idx)
{
        unsigned en_field = ctrl & 0x3;
        bool pmi = ctrl & 0x8;
        struct kvm_pmu_event_filter *filter;
        struct kvm *kvm = pmc->vcpu->kvm;

        pmc_pause_counter(pmc);

        if (!en_field || !pmc_is_enabled(pmc))
                return;

        filter = srcu_dereference(kvm->arch.pmu_event_filter, &kvm->srcu);
        if (filter) {
                if (filter->action == KVM_PMU_EVENT_DENY &&
                    test_bit(idx, (ulong *)&filter->fixed_counter_bitmap))
                        return;
                if (filter->action == KVM_PMU_EVENT_ALLOW &&
                    !test_bit(idx, (ulong *)&filter->fixed_counter_bitmap))
                        return;
        }

        if (pmc->current_config == (u64)ctrl && pmc_resume_counter(pmc))
                return;

        pmc_release_perf_event(pmc);

        pmc->current_config = (u64)ctrl;
        pmc_reprogram_counter(pmc, PERF_TYPE_HARDWARE,
                              kvm_x86_ops.pmu_ops->find_fixed_event(idx),
                              !(en_field & 0x2), /* exclude user */
                              !(en_field & 0x1), /* exclude kernel */
                              pmi, false, false);
}
EXPORT_SYMBOL_GPL(reprogram_fixed_counter);

void reprogram_counter(struct kvm_pmu *pmu, int pmc_idx)
{
        struct kvm_pmc *pmc = kvm_x86_ops.pmu_ops->pmc_idx_to_pmc(pmu, pmc_idx);

        if (!pmc)
                return;

        if (pmc_is_gp(pmc))
                reprogram_gp_counter(pmc, pmc->eventsel);
        else {
                int idx = pmc_idx - INTEL_PMC_IDX_FIXED;
                u8 ctrl = fixed_ctrl_field(pmu->fixed_ctr_ctrl, idx);

                reprogram_fixed_counter(pmc, ctrl, idx);
        }
}
EXPORT_SYMBOL_GPL(reprogram_counter);

void kvm_pmu_handle_event(struct kvm_vcpu *vcpu)
{
        struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
        int bit;

        for_each_set_bit(bit, pmu->reprogram_pmi, X86_PMC_IDX_MAX) {
                struct kvm_pmc *pmc = kvm_x86_ops.pmu_ops->pmc_idx_to_pmc(pmu, bit);

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

                reprogram_counter(pmu, bit);
        }

        /*
         * Unused perf_events are only released if the corresponding MSRs
         * weren't accessed during the last vCPU time slice. kvm_arch_sched_in
         * triggers KVM_REQ_PMU if cleanup is needed.
         */
        if (unlikely(pmu->need_cleanup))
                kvm_pmu_cleanup(vcpu);
}

/* check if idx is a valid index to access PMU */
bool kvm_pmu_is_valid_rdpmc_ecx(struct kvm_vcpu *vcpu, unsigned int idx)
{
        return kvm_x86_ops.pmu_ops->is_valid_rdpmc_ecx(vcpu, idx);
}

bool is_vmware_backdoor_pmc(u32 pmc_idx)
{
        switch (pmc_idx) {
        case VMWARE_BACKDOOR_PMC_HOST_TSC:
        case VMWARE_BACKDOOR_PMC_REAL_TIME:
        case VMWARE_BACKDOOR_PMC_APPARENT_TIME:
                return true;
        }
        return false;
}

static int kvm_pmu_rdpmc_vmware(struct kvm_vcpu *vcpu, unsigned idx, u64 *data)
{
        u64 ctr_val;

        switch (idx) {
        case VMWARE_BACKDOOR_PMC_HOST_TSC:
                ctr_val = rdtsc();
                break;
        case VMWARE_BACKDOOR_PMC_REAL_TIME:
                ctr_val = ktime_get_boottime_ns();
                break;
        case VMWARE_BACKDOOR_PMC_APPARENT_TIME:
                ctr_val = ktime_get_boottime_ns() +
                        vcpu->kvm->arch.kvmclock_offset;
                break;
        default:
                return 1;
        }

        *data = ctr_val;
        return 0;
}

int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned idx, u64 *data)
{
        bool fast_mode = idx & (1u << 31);
        struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
        struct kvm_pmc *pmc;
        u64 mask = fast_mode ? ~0u : ~0ull;

        if (!pmu->version)
                return 1;

        if (is_vmware_backdoor_pmc(idx))
                return kvm_pmu_rdpmc_vmware(vcpu, idx, data);

        pmc = kvm_x86_ops.pmu_ops->rdpmc_ecx_to_pmc(vcpu, idx, &mask);
        if (!pmc)
                return 1;

        if (!(kvm_read_cr4(vcpu) & X86_CR4_PCE) &&
            (static_call(kvm_x86_get_cpl)(vcpu) != 0) &&
            (kvm_read_cr0(vcpu) & X86_CR0_PE))
                return 1;

        *data = pmc_read_counter(pmc) & mask;
        return 0;
}

void kvm_pmu_deliver_pmi(struct kvm_vcpu *vcpu)
{
        if (lapic_in_kernel(vcpu)) {
                if (kvm_x86_ops.pmu_ops->deliver_pmi)
                        kvm_x86_ops.pmu_ops->deliver_pmi(vcpu);
                kvm_apic_local_deliver(vcpu->arch.apic, APIC_LVTPC);
        }
}

bool kvm_pmu_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
{
        return kvm_x86_ops.pmu_ops->msr_idx_to_pmc(vcpu, msr) ||
                kvm_x86_ops.pmu_ops->is_valid_msr(vcpu, msr);
}

static void kvm_pmu_mark_pmc_in_use(struct kvm_vcpu *vcpu, u32 msr)
{
        struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
        struct kvm_pmc *pmc = kvm_x86_ops.pmu_ops->msr_idx_to_pmc(vcpu, msr);

        if (pmc)
                __set_bit(pmc->idx, pmu->pmc_in_use);
}

int kvm_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
{
        return kvm_x86_ops.pmu_ops->get_msr(vcpu, msr_info);
}

int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
{
        kvm_pmu_mark_pmc_in_use(vcpu, msr_info->index);
        return kvm_x86_ops.pmu_ops->set_msr(vcpu, msr_info);
}

/* refresh PMU settings. This function generally is called when underlying
 * settings are changed (such as changes of PMU CPUID by guest VMs), which
 * should rarely happen.
 */
void kvm_pmu_refresh(struct kvm_vcpu *vcpu)
{
        kvm_x86_ops.pmu_ops->refresh(vcpu);
}

void kvm_pmu_reset(struct kvm_vcpu *vcpu)
{
        struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);

        irq_work_sync(&pmu->irq_work);
        kvm_x86_ops.pmu_ops->reset(vcpu);
}

void kvm_pmu_init(struct kvm_vcpu *vcpu)
{
        struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);

        memset(pmu, 0, sizeof(*pmu));
        kvm_x86_ops.pmu_ops->init(vcpu);
        init_irq_work(&pmu->irq_work, kvm_pmi_trigger_fn);
        pmu->event_count = 0;
        pmu->need_cleanup = false;
        kvm_pmu_refresh(vcpu);
}

static inline bool pmc_speculative_in_use(struct kvm_pmc *pmc)
{
        struct kvm_pmu *pmu = pmc_to_pmu(pmc);

        if (pmc_is_fixed(pmc))
                return fixed_ctrl_field(pmu->fixed_ctr_ctrl,
                        pmc->idx - INTEL_PMC_IDX_FIXED) & 0x3;

        return pmc->eventsel & ARCH_PERFMON_EVENTSEL_ENABLE;
}

/* Release perf_events for vPMCs that have been unused for a full time slice.  */
void kvm_pmu_cleanup(struct kvm_vcpu *vcpu)
{
        struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
        struct kvm_pmc *pmc = NULL;
        DECLARE_BITMAP(bitmask, X86_PMC_IDX_MAX);
        int i;

        pmu->need_cleanup = false;

        bitmap_andnot(bitmask, pmu->all_valid_pmc_idx,
                      pmu->pmc_in_use, X86_PMC_IDX_MAX);

        for_each_set_bit(i, bitmask, X86_PMC_IDX_MAX) {
                pmc = kvm_x86_ops.pmu_ops->pmc_idx_to_pmc(pmu, i);

                if (pmc && pmc->perf_event && !pmc_speculative_in_use(pmc))
                        pmc_stop_counter(pmc);
        }

        if (kvm_x86_ops.pmu_ops->cleanup)
                kvm_x86_ops.pmu_ops->cleanup(vcpu);

        bitmap_zero(pmu->pmc_in_use, X86_PMC_IDX_MAX);
}

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

int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
{
        struct kvm_pmu_event_filter tmp, *filter;
        size_t size;
        int r;

        if (copy_from_user(&tmp, argp, sizeof(tmp)))
                return -EFAULT;

        if (tmp.action != KVM_PMU_EVENT_ALLOW &&
            tmp.action != KVM_PMU_EVENT_DENY)
                return -EINVAL;

        if (tmp.flags != 0)
                return -EINVAL;

        if (tmp.nevents > KVM_PMU_EVENT_FILTER_MAX_EVENTS)
                return -E2BIG;

        size = struct_size(filter, events, tmp.nevents);
        filter = kmalloc(size, GFP_KERNEL_ACCOUNT);
        if (!filter)
                return -ENOMEM;

        r = -EFAULT;
        if (copy_from_user(filter, argp, size))
                goto cleanup;

        /* Ensure nevents can't be changed between the user copies. */
        *filter = tmp;

        mutex_lock(&kvm->lock);
        filter = rcu_replace_pointer(kvm->arch.pmu_event_filter, filter,
                                     mutex_is_locked(&kvm->lock));
        mutex_unlock(&kvm->lock);

        synchronize_srcu_expedited(&kvm->srcu);
        r = 0;
cleanup:
        kfree(filter);
        return r;
}