/*
 * Copyright (C) 2015 Linaro Ltd.
 * Author: Shannon Zhao <shannon.zhao@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/cpu.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/perf_event.h>
#include <linux/perf/arm_pmu.h>
#include <linux/uaccess.h>
#include <asm/kvm_emulate.h>
#include <kvm/arm_pmu.h>
#include <kvm/arm_vgic.h>

static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx);
static void kvm_pmu_update_pmc_chained(struct kvm_vcpu *vcpu, u64 select_idx);
static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc);

#define PERF_ATTR_CFG1_KVM_PMU_CHAINED 0x1

/**
 * kvm_pmu_idx_is_64bit - determine if select_idx is a 64bit counter
 * @vcpu: The vcpu pointer
 * @select_idx: The counter index
 */
static bool kvm_pmu_idx_is_64bit(struct kvm_vcpu *vcpu, u64 select_idx)
{
        return (select_idx == ARMV8_PMU_CYCLE_IDX &&
                __vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_LC);
}

static struct kvm_vcpu *kvm_pmc_to_vcpu(struct kvm_pmc *pmc)
{
        struct kvm_pmu *pmu;
        struct kvm_vcpu_arch *vcpu_arch;

        pmc -= pmc->idx;
        pmu = container_of(pmc, struct kvm_pmu, pmc[0]);
        vcpu_arch = container_of(pmu, struct kvm_vcpu_arch, pmu);
        return container_of(vcpu_arch, struct kvm_vcpu, arch);
}

/**
 * kvm_pmu_pmc_is_chained - determine if the pmc is chained
 * @pmc: The PMU counter pointer
 */
static bool kvm_pmu_pmc_is_chained(struct kvm_pmc *pmc)
{
        struct kvm_vcpu *vcpu = kvm_pmc_to_vcpu(pmc);

        return test_bit(pmc->idx >> 1, vcpu->arch.pmu.chained);
}

/**
 * kvm_pmu_idx_is_high_counter - determine if select_idx is a high/low counter
 * @select_idx: The counter index
 */
static bool kvm_pmu_idx_is_high_counter(u64 select_idx)
{
        return select_idx & 0x1;
}

/**
 * kvm_pmu_get_canonical_pmc - obtain the canonical pmc
 * @pmc: The PMU counter pointer
 *
 * When a pair of PMCs are chained together we use the low counter (canonical)
 * to hold the underlying perf event.
 */
static struct kvm_pmc *kvm_pmu_get_canonical_pmc(struct kvm_pmc *pmc)
{
        if (kvm_pmu_pmc_is_chained(pmc) &&
            kvm_pmu_idx_is_high_counter(pmc->idx))
                return pmc - 1;

        return pmc;
}
static struct kvm_pmc *kvm_pmu_get_alternate_pmc(struct kvm_pmc *pmc)
{
        if (kvm_pmu_idx_is_high_counter(pmc->idx))
                return pmc - 1;
        else
                return pmc + 1;
}

/**
 * kvm_pmu_idx_has_chain_evtype - determine if the event type is chain
 * @vcpu: The vcpu pointer
 * @select_idx: The counter index
 */
static bool kvm_pmu_idx_has_chain_evtype(struct kvm_vcpu *vcpu, u64 select_idx)
{
        u64 eventsel, reg;

        select_idx |= 0x1;

        if (select_idx == ARMV8_PMU_CYCLE_IDX)
                return false;

        reg = PMEVTYPER0_EL0 + select_idx;
        eventsel = __vcpu_sys_reg(vcpu, reg) & ARMV8_PMU_EVTYPE_EVENT;

        return eventsel == ARMV8_PMUV3_PERFCTR_CHAIN;
}

/**
 * kvm_pmu_get_pair_counter_value - get PMU counter value
 * @vcpu: The vcpu pointer
 * @pmc: The PMU counter pointer
 */
static u64 kvm_pmu_get_pair_counter_value(struct kvm_vcpu *vcpu,
                                          struct kvm_pmc *pmc)
{
        u64 counter, counter_high, reg, enabled, running;

        if (kvm_pmu_pmc_is_chained(pmc)) {
                pmc = kvm_pmu_get_canonical_pmc(pmc);
                reg = PMEVCNTR0_EL0 + pmc->idx;

                counter = __vcpu_sys_reg(vcpu, reg);
                counter_high = __vcpu_sys_reg(vcpu, reg + 1);

                counter = lower_32_bits(counter) | (counter_high << 32);
        } else {
                reg = (pmc->idx == ARMV8_PMU_CYCLE_IDX)
                      ? PMCCNTR_EL0 : PMEVCNTR0_EL0 + pmc->idx;
                counter = __vcpu_sys_reg(vcpu, reg);
        }

        /*
         * The real counter value is equal to the value of counter register plus
         * the value perf event counts.
         */
        if (pmc->perf_event)
                counter += perf_event_read_value(pmc->perf_event, &enabled,
                                                 &running);

        return counter;
}

/**
 * kvm_pmu_get_counter_value - get PMU counter value
 * @vcpu: The vcpu pointer
 * @select_idx: The counter index
 */
u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx)
{
        u64 counter;
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        struct kvm_pmc *pmc = &pmu->pmc[select_idx];

        counter = kvm_pmu_get_pair_counter_value(vcpu, pmc);

        if (kvm_pmu_pmc_is_chained(pmc) &&
            kvm_pmu_idx_is_high_counter(select_idx))
                counter = upper_32_bits(counter);
        else if (select_idx != ARMV8_PMU_CYCLE_IDX)
                counter = lower_32_bits(counter);

        return counter;
}

/**
 * kvm_pmu_set_counter_value - set PMU counter value
 * @vcpu: The vcpu pointer
 * @select_idx: The counter index
 * @val: The counter value
 */
void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, u64 select_idx, u64 val)
{
        u64 reg;

        reg = (select_idx == ARMV8_PMU_CYCLE_IDX)
              ? PMCCNTR_EL0 : PMEVCNTR0_EL0 + select_idx;
        __vcpu_sys_reg(vcpu, reg) += (s64)val - kvm_pmu_get_counter_value(vcpu, select_idx);

        /* Recreate the perf event to reflect the updated sample_period */
        kvm_pmu_create_perf_event(vcpu, select_idx);
}

/**
 * kvm_pmu_release_perf_event - remove the perf event
 * @pmc: The PMU counter pointer
 */
static void kvm_pmu_release_perf_event(struct kvm_pmc *pmc)
{
        pmc = kvm_pmu_get_canonical_pmc(pmc);
        if (pmc->perf_event) {
                perf_event_disable(pmc->perf_event);
                perf_event_release_kernel(pmc->perf_event);
                pmc->perf_event = NULL;
        }
}

/**
 * kvm_pmu_stop_counter - stop PMU counter
 * @pmc: The PMU counter pointer
 *
 * If this counter has been configured to monitor some event, release it here.
 */
static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc)
{
        u64 counter, reg, val;

        pmc = kvm_pmu_get_canonical_pmc(pmc);
        if (!pmc->perf_event)
                return;

        counter = kvm_pmu_get_pair_counter_value(vcpu, pmc);

        if (pmc->idx == ARMV8_PMU_CYCLE_IDX) {
                reg = PMCCNTR_EL0;
                val = counter;
        } else {
                reg = PMEVCNTR0_EL0 + pmc->idx;
                val = lower_32_bits(counter);
        }

        __vcpu_sys_reg(vcpu, reg) = val;

        if (kvm_pmu_pmc_is_chained(pmc))
                __vcpu_sys_reg(vcpu, reg + 1) = upper_32_bits(counter);

        kvm_pmu_release_perf_event(pmc);
}

/**
 * kvm_pmu_vcpu_init - assign pmu counter idx for cpu
 * @vcpu: The vcpu pointer
 *
 */
void kvm_pmu_vcpu_init(struct kvm_vcpu *vcpu)
{
        int i;
        struct kvm_pmu *pmu = &vcpu->arch.pmu;

        for (i = 0; i < ARMV8_PMU_MAX_COUNTERS; i++)
                pmu->pmc[i].idx = i;
}

/**
 * kvm_pmu_vcpu_reset - reset pmu state for cpu
 * @vcpu: The vcpu pointer
 *
 */
void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu)
{
        unsigned long mask = kvm_pmu_valid_counter_mask(vcpu);
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        int i;

        for_each_set_bit(i, &mask, 32)
                kvm_pmu_stop_counter(vcpu, &pmu->pmc[i]);

        bitmap_zero(vcpu->arch.pmu.chained, ARMV8_PMU_MAX_COUNTER_PAIRS);
}

/**
 * kvm_pmu_vcpu_destroy - free perf event of PMU for cpu
 * @vcpu: The vcpu pointer
 *
 */
void kvm_pmu_vcpu_destroy(struct kvm_vcpu *vcpu)
{
        int i;
        struct kvm_pmu *pmu = &vcpu->arch.pmu;

        for (i = 0; i < ARMV8_PMU_MAX_COUNTERS; i++)
                kvm_pmu_release_perf_event(&pmu->pmc[i]);
}

u64 kvm_pmu_valid_counter_mask(struct kvm_vcpu *vcpu)
{
        u64 val = __vcpu_sys_reg(vcpu, PMCR_EL0) >> ARMV8_PMU_PMCR_N_SHIFT;

        val &= ARMV8_PMU_PMCR_N_MASK;
        if (val == 0)
                return BIT(ARMV8_PMU_CYCLE_IDX);
        else
                return GENMASK(val - 1, 0) | BIT(ARMV8_PMU_CYCLE_IDX);
}

/**
 * kvm_pmu_enable_counter_mask - enable selected PMU counters
 * @vcpu: The vcpu pointer
 * @val: the value guest writes to PMCNTENSET register
 *
 * Call perf_event_enable to start counting the perf event
 */
void kvm_pmu_enable_counter_mask(struct kvm_vcpu *vcpu, u64 val)
{
        int i;
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        struct kvm_pmc *pmc;

        if (!(__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E) || !val)
                return;

        for (i = 0; i < ARMV8_PMU_MAX_COUNTERS; i++) {
                if (!(val & BIT(i)))
                        continue;

                pmc = &pmu->pmc[i];

                /* A change in the enable state may affect the chain state */
                kvm_pmu_update_pmc_chained(vcpu, i);
                kvm_pmu_create_perf_event(vcpu, i);

                /* At this point, pmc must be the canonical */
                if (pmc->perf_event) {
                        perf_event_enable(pmc->perf_event);
                        if (pmc->perf_event->state != PERF_EVENT_STATE_ACTIVE)
                                kvm_debug("fail to enable perf event\n");
                }
        }
}

/**
 * kvm_pmu_disable_counter_mask - disable selected PMU counters
 * @vcpu: The vcpu pointer
 * @val: the value guest writes to PMCNTENCLR register
 *
 * Call perf_event_disable to stop counting the perf event
 */
void kvm_pmu_disable_counter_mask(struct kvm_vcpu *vcpu, u64 val)
{
        int i;
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        struct kvm_pmc *pmc;

        if (!val)
                return;

        for (i = 0; i < ARMV8_PMU_MAX_COUNTERS; i++) {
                if (!(val & BIT(i)))
                        continue;

                pmc = &pmu->pmc[i];

                /* A change in the enable state may affect the chain state */
                kvm_pmu_update_pmc_chained(vcpu, i);
                kvm_pmu_create_perf_event(vcpu, i);

                /* At this point, pmc must be the canonical */
                if (pmc->perf_event)
                        perf_event_disable(pmc->perf_event);
        }
}

static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
{
        u64 reg = 0;

        if ((__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E)) {
                reg = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
                reg &= __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
                reg &= __vcpu_sys_reg(vcpu, PMINTENSET_EL1);
                reg &= kvm_pmu_valid_counter_mask(vcpu);
        }

        return reg;
}

static void kvm_pmu_update_state(struct kvm_vcpu *vcpu)
{
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        bool overflow;

        if (!kvm_arm_pmu_v3_ready(vcpu))
                return;

        overflow = !!kvm_pmu_overflow_status(vcpu);
        if (pmu->irq_level == overflow)
                return;

        pmu->irq_level = overflow;

        if (likely(irqchip_in_kernel(vcpu->kvm))) {
                int ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
                                              pmu->irq_num, overflow, pmu);
                WARN_ON(ret);
        }
}

bool kvm_pmu_should_notify_user(struct kvm_vcpu *vcpu)
{
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        struct kvm_sync_regs *sregs = &vcpu->run->s.regs;
        bool run_level = sregs->device_irq_level & KVM_ARM_DEV_PMU;

        if (likely(irqchip_in_kernel(vcpu->kvm)))
                return false;

        return pmu->irq_level != run_level;
}

/*
 * Reflect the PMU overflow interrupt output level into the kvm_run structure
 */
void kvm_pmu_update_run(struct kvm_vcpu *vcpu)
{
        struct kvm_sync_regs *regs = &vcpu->run->s.regs;

        /* Populate the timer bitmap for user space */
        regs->device_irq_level &= ~KVM_ARM_DEV_PMU;
        if (vcpu->arch.pmu.irq_level)
                regs->device_irq_level |= KVM_ARM_DEV_PMU;
}

/**
 * kvm_pmu_flush_hwstate - flush pmu state to cpu
 * @vcpu: The vcpu pointer
 *
 * Check if the PMU has overflowed while we were running in the host, and inject
 * an interrupt if that was the case.
 */
void kvm_pmu_flush_hwstate(struct kvm_vcpu *vcpu)
{
        kvm_pmu_update_state(vcpu);
}

/**
 * kvm_pmu_sync_hwstate - sync pmu state from cpu
 * @vcpu: The vcpu pointer
 *
 * Check if the PMU has overflowed while we were running in the guest, and
 * inject an interrupt if that was the case.
 */
void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu)
{
        kvm_pmu_update_state(vcpu);
}

/**
 * When the perf event overflows, set the overflow status and inform the vcpu.
 */
static void kvm_pmu_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 arm_pmu *cpu_pmu = to_arm_pmu(perf_event->pmu);
        struct kvm_vcpu *vcpu = kvm_pmc_to_vcpu(pmc);
        int idx = pmc->idx;
        u64 period;

        cpu_pmu->pmu.stop(perf_event, PERF_EF_UPDATE);

        /*
         * Reset the sample period to the architectural limit,
         * i.e. the point where the counter overflows.
         */
        period = -(local64_read(&perf_event->count));

        if (!kvm_pmu_idx_is_64bit(vcpu, pmc->idx))
                period &= GENMASK(31, 0);

        local64_set(&perf_event->hw.period_left, 0);
        perf_event->attr.sample_period = period;
        perf_event->hw.sample_period = period;

        __vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= BIT(idx);

        if (kvm_pmu_overflow_status(vcpu)) {
                kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
                kvm_vcpu_kick(vcpu);
        }

        cpu_pmu->pmu.start(perf_event, PERF_EF_RELOAD);
}

/**
 * kvm_pmu_software_increment - do software increment
 * @vcpu: The vcpu pointer
 * @val: the value guest writes to PMSWINC register
 */
void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val)
{
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        int i;

        if (!(__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E))
                return;

        /* Weed out disabled counters */
        val &= __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);

        for (i = 0; i < ARMV8_PMU_CYCLE_IDX; i++) {
                u64 type, reg;

                if (!(val & BIT(i)))
                        continue;

                /* PMSWINC only applies to ... SW_INC! */
                type = __vcpu_sys_reg(vcpu, PMEVTYPER0_EL0 + i);
                type &= ARMV8_PMU_EVTYPE_EVENT;
                if (type != ARMV8_PMUV3_PERFCTR_SW_INCR)
                        continue;

                /* increment this even SW_INC counter */
                reg = __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) + 1;
                reg = lower_32_bits(reg);
                __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) = reg;

                if (reg) /* no overflow on the low part */
                        continue;

                if (kvm_pmu_pmc_is_chained(&pmu->pmc[i])) {
                        /* increment the high counter */
                        reg = __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i + 1) + 1;
                        reg = lower_32_bits(reg);
                        __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i + 1) = reg;
                        if (!reg) /* mark overflow on the high counter */
                                __vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= BIT(i + 1);
                } else {
                        /* mark overflow on low counter */
                        __vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= BIT(i);
                }
        }
}

/**
 * kvm_pmu_handle_pmcr - handle PMCR register
 * @vcpu: The vcpu pointer
 * @val: the value guest writes to PMCR register
 */
void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val)
{
        unsigned long mask = kvm_pmu_valid_counter_mask(vcpu);
        int i;

        if (val & ARMV8_PMU_PMCR_E) {
                kvm_pmu_enable_counter_mask(vcpu,
                       __vcpu_sys_reg(vcpu, PMCNTENSET_EL0) & mask);
        } else {
                kvm_pmu_disable_counter_mask(vcpu, mask);
        }

        if (val & ARMV8_PMU_PMCR_C)
                kvm_pmu_set_counter_value(vcpu, ARMV8_PMU_CYCLE_IDX, 0);

        if (val & ARMV8_PMU_PMCR_P) {
                for_each_set_bit(i, &mask, 32)
                        kvm_pmu_set_counter_value(vcpu, i, 0);
        }
}

static bool kvm_pmu_counter_is_enabled(struct kvm_vcpu *vcpu, u64 select_idx)
{
        return (__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E) &&
               (__vcpu_sys_reg(vcpu, PMCNTENSET_EL0) & BIT(select_idx));
}

/**
 * kvm_pmu_create_perf_event - create a perf event for a counter
 * @vcpu: The vcpu pointer
 * @select_idx: The number of selected counter
 */
static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx)
{
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        struct kvm_pmc *pmc;
        struct perf_event *event;
        struct perf_event_attr attr;
        u64 eventsel, counter, reg, data;

        /*
         * For chained counters the event type and filtering attributes are
         * obtained from the low/even counter. We also use this counter to
         * determine if the event is enabled/disabled.
         */
        pmc = kvm_pmu_get_canonical_pmc(&pmu->pmc[select_idx]);

        reg = (pmc->idx == ARMV8_PMU_CYCLE_IDX)
              ? PMCCFILTR_EL0 : PMEVTYPER0_EL0 + pmc->idx;
        data = __vcpu_sys_reg(vcpu, reg);

        kvm_pmu_stop_counter(vcpu, pmc);
        eventsel = data & ARMV8_PMU_EVTYPE_EVENT;

        /* Software increment event does't need to be backed by a perf event */
        if (eventsel == ARMV8_PMUV3_PERFCTR_SW_INCR &&
            pmc->idx != ARMV8_PMU_CYCLE_IDX)
                return;

        memset(&attr, 0, sizeof(struct perf_event_attr));
        attr.type = PERF_TYPE_RAW;
        attr.size = sizeof(attr);
        attr.pinned = 1;
        attr.disabled = !kvm_pmu_counter_is_enabled(vcpu, pmc->idx);
        attr.exclude_user = data & ARMV8_PMU_EXCLUDE_EL0 ? 1 : 0;
        attr.exclude_kernel = data & ARMV8_PMU_EXCLUDE_EL1 ? 1 : 0;
        attr.exclude_hv = 1; /* Don't count EL2 events */
        attr.exclude_host = 1; /* Don't count host events */
        attr.config = (pmc->idx == ARMV8_PMU_CYCLE_IDX) ?
                ARMV8_PMUV3_PERFCTR_CPU_CYCLES : eventsel;

        counter = kvm_pmu_get_pair_counter_value(vcpu, pmc);

        if (kvm_pmu_pmc_is_chained(pmc)) {
                /**
                 * The initial sample period (overflow count) of an event. For
                 * chained counters we only support overflow interrupts on the
                 * high counter.
                 */
                attr.sample_period = (-counter) & GENMASK(63, 0);
                attr.config1 |= PERF_ATTR_CFG1_KVM_PMU_CHAINED;

                event = perf_event_create_kernel_counter(&attr, -1, current,
                                                         kvm_pmu_perf_overflow,
                                                         pmc + 1);
        } else {
                /* The initial sample period (overflow count) of an event. */
                if (kvm_pmu_idx_is_64bit(vcpu, pmc->idx))
                        attr.sample_period = (-counter) & GENMASK(63, 0);
                else
                        attr.sample_period = (-counter) & GENMASK(31, 0);

                event = perf_event_create_kernel_counter(&attr, -1, current,
                                                 kvm_pmu_perf_overflow, pmc);
        }

        if (IS_ERR(event)) {
                pr_err_once("kvm: pmu event creation failed %ld\n",
                            PTR_ERR(event));
                return;
        }

        pmc->perf_event = event;
}

/**
 * kvm_pmu_update_pmc_chained - update chained bitmap
 * @vcpu: The vcpu pointer
 * @select_idx: The number of selected counter
 *
 * Update the chained bitmap based on the event type written in the
 * typer register and the enable state of the odd register.
 */
static void kvm_pmu_update_pmc_chained(struct kvm_vcpu *vcpu, u64 select_idx)
{
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        struct kvm_pmc *pmc = &pmu->pmc[select_idx], *canonical_pmc;
        bool new_state, old_state;

        old_state = kvm_pmu_pmc_is_chained(pmc);
        new_state = kvm_pmu_idx_has_chain_evtype(vcpu, pmc->idx) &&
                    kvm_pmu_counter_is_enabled(vcpu, pmc->idx | 0x1);

        if (old_state == new_state)
                return;

        canonical_pmc = kvm_pmu_get_canonical_pmc(pmc);
        kvm_pmu_stop_counter(vcpu, canonical_pmc);
        if (new_state) {
                /*
                 * During promotion from !chained to chained we must ensure
                 * the adjacent counter is stopped and its event destroyed
                 */
                kvm_pmu_stop_counter(vcpu, kvm_pmu_get_alternate_pmc(pmc));
                set_bit(pmc->idx >> 1, vcpu->arch.pmu.chained);
                return;
        }
        clear_bit(pmc->idx >> 1, vcpu->arch.pmu.chained);
}

/**
 * kvm_pmu_set_counter_event_type - set selected counter to monitor some event
 * @vcpu: The vcpu pointer
 * @data: The data guest writes to PMXEVTYPER_EL0
 * @select_idx: The number of selected counter
 *
 * When OS accesses PMXEVTYPER_EL0, that means it wants to set a PMC to count an
 * event with given hardware event number. Here we call perf_event API to
 * emulate this action and create a kernel perf event for it.
 */
void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
                                    u64 select_idx)
{
        u64 reg, event_type = data & ARMV8_PMU_EVTYPE_MASK;

        reg = (select_idx == ARMV8_PMU_CYCLE_IDX)
              ? PMCCFILTR_EL0 : PMEVTYPER0_EL0 + select_idx;

        __vcpu_sys_reg(vcpu, reg) = event_type;

        kvm_pmu_update_pmc_chained(vcpu, select_idx);
        kvm_pmu_create_perf_event(vcpu, select_idx);
}

bool kvm_arm_support_pmu_v3(void)
{
        /*
         * Check if HW_PERF_EVENTS are supported by checking the number of
         * hardware performance counters. This could ensure the presence of
         * a physical PMU and CONFIG_PERF_EVENT is selected.
         */
        return (perf_num_counters() > 0);
}

int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu)
{
        if (!vcpu->arch.pmu.created)
                return 0;

        /*
         * A valid interrupt configuration for the PMU is either to have a
         * properly configured interrupt number and using an in-kernel
         * irqchip, or to not have an in-kernel GIC and not set an IRQ.
         */
        if (irqchip_in_kernel(vcpu->kvm)) {
                int irq = vcpu->arch.pmu.irq_num;
                if (!kvm_arm_pmu_irq_initialized(vcpu))
                        return -EINVAL;

                /*
                 * If we are using an in-kernel vgic, at this point we know
                 * the vgic will be initialized, so we can check the PMU irq
                 * number against the dimensions of the vgic and make sure
                 * it's valid.
                 */
                if (!irq_is_ppi(irq) && !vgic_valid_spi(vcpu->kvm, irq))
                        return -EINVAL;
        } else if (kvm_arm_pmu_irq_initialized(vcpu)) {
                   return -EINVAL;
        }

        kvm_pmu_vcpu_reset(vcpu);
        vcpu->arch.pmu.ready = true;

        return 0;
}

static int kvm_arm_pmu_v3_init(struct kvm_vcpu *vcpu)
{
        if (!kvm_arm_support_pmu_v3())
                return -ENODEV;

        if (!test_bit(KVM_ARM_VCPU_PMU_V3, vcpu->arch.features))
                return -ENXIO;

        if (vcpu->arch.pmu.created)
                return -EBUSY;

        if (irqchip_in_kernel(vcpu->kvm)) {
                int ret;

                /*
                 * If using the PMU with an in-kernel virtual GIC
                 * implementation, we require the GIC to be already
                 * initialized when initializing the PMU.
                 */
                if (!vgic_initialized(vcpu->kvm))
                        return -ENODEV;

                if (!kvm_arm_pmu_irq_initialized(vcpu))
                        return -ENXIO;

                ret = kvm_vgic_set_owner(vcpu, vcpu->arch.pmu.irq_num,
                                         &vcpu->arch.pmu);
                if (ret)
                        return ret;
        }

        vcpu->arch.pmu.created = true;
        return 0;
}

/*
 * For one VM the interrupt type must be same for each vcpu.
 * As a PPI, the interrupt number is the same for all vcpus,
 * while as an SPI it must be a separate number per vcpu.
 */
static bool pmu_irq_is_valid(struct kvm *kvm, int irq)
{
        int i;
        struct kvm_vcpu *vcpu;

        kvm_for_each_vcpu(i, vcpu, kvm) {
                if (!kvm_arm_pmu_irq_initialized(vcpu))
                        continue;

                if (irq_is_ppi(irq)) {
                        if (vcpu->arch.pmu.irq_num != irq)
                                return false;
                } else {
                        if (vcpu->arch.pmu.irq_num == irq)
                                return false;
                }
        }

        return true;
}

int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
{
        switch (attr->attr) {
        case KVM_ARM_VCPU_PMU_V3_IRQ: {
                int __user *uaddr = (int __user *)(long)attr->addr;
                int irq;

                if (!irqchip_in_kernel(vcpu->kvm))
                        return -EINVAL;

                if (!test_bit(KVM_ARM_VCPU_PMU_V3, vcpu->arch.features))
                        return -ENODEV;

                if (get_user(irq, uaddr))
                        return -EFAULT;

                /* The PMU overflow interrupt can be a PPI or a valid SPI. */
                if (!(irq_is_ppi(irq) || irq_is_spi(irq)))
                        return -EINVAL;

                if (!pmu_irq_is_valid(vcpu->kvm, irq))
                        return -EINVAL;

                if (kvm_arm_pmu_irq_initialized(vcpu))
                        return -EBUSY;

                kvm_debug("Set kvm ARM PMU irq: %d\n", irq);
                vcpu->arch.pmu.irq_num = irq;
                return 0;
        }
        case KVM_ARM_VCPU_PMU_V3_INIT:
                return kvm_arm_pmu_v3_init(vcpu);
        }

        return -ENXIO;
}

int kvm_arm_pmu_v3_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
{
        switch (attr->attr) {
        case KVM_ARM_VCPU_PMU_V3_IRQ: {
                int __user *uaddr = (int __user *)(long)attr->addr;
                int irq;

                if (!irqchip_in_kernel(vcpu->kvm))
                        return -EINVAL;

                if (!test_bit(KVM_ARM_VCPU_PMU_V3, vcpu->arch.features))
                        return -ENODEV;

                if (!kvm_arm_pmu_irq_initialized(vcpu))
                        return -ENXIO;

                irq = vcpu->arch.pmu.irq_num;
                return put_user(irq, uaddr);
        }
        }

        return -ENXIO;
}

int kvm_arm_pmu_v3_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
{
        switch (attr->attr) {
        case KVM_ARM_VCPU_PMU_V3_IRQ:
        case KVM_ARM_VCPU_PMU_V3_INIT:
                if (kvm_arm_support_pmu_v3() &&
                    test_bit(KVM_ARM_VCPU_PMU_V3, vcpu->arch.features))
                        return 0;
        }

        return -ENXIO;
}