/*
 * 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/uaccess.h>
#include <asm/kvm_emulate.h>
#include <kvm/arm_pmu.h>
#include <kvm/arm_vgic.h>

/**
 * 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, reg, enabled, running;
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        struct kvm_pmc *pmc = &pmu->pmc[select_idx];

        reg = (select_idx == ARMV8_PMU_CYCLE_IDX)
              ? PMCCNTR_EL0 : PMEVCNTR0_EL0 + select_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 & pmc->bitmask;
}

/**
 * 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);
}

/**
 * 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;

        if (pmc->perf_event) {
                counter = kvm_pmu_get_counter_value(vcpu, pmc->idx);
                reg = (pmc->idx == ARMV8_PMU_CYCLE_IDX)
                       ? PMCCNTR_EL0 : PMEVCNTR0_EL0 + pmc->idx;
                vcpu_sys_reg(vcpu, reg) = counter;
                perf_event_disable(pmc->perf_event);
                perf_event_release_kernel(pmc->perf_event);
                pmc->perf_event = NULL;
        }
}

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

        for (i = 0; i < ARMV8_PMU_MAX_COUNTERS; i++) {
                kvm_pmu_stop_counter(vcpu, &pmu->pmc[i]);
                pmu->pmc[i].idx = i;
                pmu->pmc[i].bitmask = 0xffffffffUL;
        }
}

/**
 * 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++) {
                struct kvm_pmc *pmc = &pmu->pmc[i];

                if (pmc->perf_event) {
                        perf_event_disable(pmc->perf_event);
                        perf_event_release_kernel(pmc->perf_event);
                        pmc->perf_event = NULL;
                }
        }
}

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 - enable selected PMU counter
 * @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(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];
                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 - disable selected PMU counter
 * @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(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];
                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;
}

/**
 * kvm_pmu_overflow_set - set PMU overflow interrupt
 * @vcpu: The vcpu pointer
 * @val: the value guest writes to PMOVSSET register
 */
void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val)
{
        u64 reg;

        if (val == 0)
                return;

        vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= val;
        reg = kvm_pmu_overflow_status(vcpu);
        if (reg != 0)
                kvm_vcpu_kick(vcpu);
}

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) {
                pmu->irq_level = overflow;
                kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
                                    pmu->irq_num, overflow);
        }
}

/**
 * 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);
}

static inline 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);
}

/**
 * When perf event overflows, call kvm_pmu_overflow_set to set overflow status.
 */
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 kvm_vcpu *vcpu = kvm_pmc_to_vcpu(pmc);
        int idx = pmc->idx;

        kvm_pmu_overflow_set(vcpu, BIT(idx));
}

/**
 * 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)
{
        int i;
        u64 type, enable, reg;

        if (val == 0)
                return;

        enable = vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
        for (i = 0; i < ARMV8_PMU_CYCLE_IDX; i++) {
                if (!(val & BIT(i)))
                        continue;
                type = vcpu_sys_reg(vcpu, PMEVTYPER0_EL0 + i)
                       & ARMV8_PMU_EVTYPE_EVENT;
                if ((type == ARMV8_PMU_EVTYPE_EVENT_SW_INCR)
                    && (enable & BIT(i))) {
                        reg = vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) + 1;
                        reg = lower_32_bits(reg);
                        vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) = reg;
                        if (!reg)
                                kvm_pmu_overflow_set(vcpu, 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)
{
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        struct kvm_pmc *pmc;
        u64 mask;
        int i;

        mask = kvm_pmu_valid_counter_mask(vcpu);
        if (val & ARMV8_PMU_PMCR_E) {
                kvm_pmu_enable_counter(vcpu,
                                vcpu_sys_reg(vcpu, PMCNTENSET_EL0) & mask);
        } else {
                kvm_pmu_disable_counter(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 (i = 0; i < ARMV8_PMU_CYCLE_IDX; i++)
                        kvm_pmu_set_counter_value(vcpu, i, 0);
        }

        if (val & ARMV8_PMU_PMCR_LC) {
                pmc = &pmu->pmc[ARMV8_PMU_CYCLE_IDX];
                pmc->bitmask = 0xffffffffffffffffUL;
        }
}

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_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)
{
        struct kvm_pmu *pmu = &vcpu->arch.pmu;
        struct kvm_pmc *pmc = &pmu->pmc[select_idx];
        struct perf_event *event;
        struct perf_event_attr attr;
        u64 eventsel, counter;

        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_PMU_EVTYPE_EVENT_SW_INCR)
                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, select_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 = eventsel;

        counter = kvm_pmu_get_counter_value(vcpu, select_idx);
        /* The initial sample period (overflow count) of an event. */
        attr.sample_period = (-counter) & pmc->bitmask;

        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;
}

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);
}

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

        if (kvm_arm_pmu_v3_ready(vcpu))
                return -EBUSY;

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

        return 0;
}

static bool irq_is_valid(struct kvm *kvm, int irq, bool is_ppi)
{
        int i;
        struct kvm_vcpu *vcpu;

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

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

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

                /*
                 * The PMU overflow interrupt could be a PPI or SPI, but 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.
                 */
                if (irq < VGIC_NR_SGIS || irq >= vcpu->kvm->arch.vgic.nr_irqs ||
                    !irq_is_valid(vcpu->kvm, irq, irq < VGIC_NR_PRIVATE_IRQS))
                        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 (!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;
}