/*
 *  Copyright (C) 2001  MandrakeSoft S.A.
 *  Copyright 2010 Red Hat, Inc. and/or its affiliates.
 *
 *    MandrakeSoft S.A.
 *    43, rue d'Aboukir
 *    75002 Paris - France
 *    http://www.linux-mandrake.com/
 *    http://www.mandrakesoft.com/
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 *  Yunhong Jiang <yunhong.jiang@intel.com>
 *  Yaozu (Eddie) Dong <eddie.dong@intel.com>
 *  Based on Xen 3.1 code.
 */

#include <linux/kvm_host.h>
#include <linux/kvm.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/smp.h>
#include <linux/hrtimer.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/current.h>
#include <trace/events/kvm.h>

#include "ioapic.h"
#include "lapic.h"
#include "irq.h"

static int ioapic_service(struct kvm_ioapic *vioapic, int irq,
                bool line_status);

static unsigned long ioapic_read_indirect(struct kvm_ioapic *ioapic,
                                          unsigned long addr,
                                          unsigned long length)
{
        unsigned long result = 0;

        switch (ioapic->ioregsel) {
        case IOAPIC_REG_VERSION:
                result = ((((IOAPIC_NUM_PINS - 1) & 0xff) << 16)
                          | (IOAPIC_VERSION_ID & 0xff));
                break;

        case IOAPIC_REG_APIC_ID:
        case IOAPIC_REG_ARB_ID:
                result = ((ioapic->id & 0xf) << 24);
                break;

        default:
                {
                        u32 redir_index = (ioapic->ioregsel - 0x10) >> 1;
                        u64 redir_content;

                        if (redir_index < IOAPIC_NUM_PINS)
                                redir_content =
                                        ioapic->redirtbl[redir_index].bits;
                        else
                                redir_content = ~0ULL;

                        result = (ioapic->ioregsel & 0x1) ?
                            (redir_content >> 32) & 0xffffffff :
                            redir_content & 0xffffffff;
                        break;
                }
        }

        return result;
}

static void rtc_irq_eoi_tracking_reset(struct kvm_ioapic *ioapic)
{
        ioapic->rtc_status.pending_eoi = 0;
        bitmap_zero(ioapic->rtc_status.dest_map.map, KVM_MAX_VCPU_ID);
}

static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic);

static void rtc_status_pending_eoi_check_valid(struct kvm_ioapic *ioapic)
{
        if (WARN_ON(ioapic->rtc_status.pending_eoi < 0))
                kvm_rtc_eoi_tracking_restore_all(ioapic);
}

static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
{
        bool new_val, old_val;
        struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
        struct dest_map *dest_map = &ioapic->rtc_status.dest_map;
        union kvm_ioapic_redirect_entry *e;

        e = &ioapic->redirtbl[RTC_GSI];
        if (!kvm_apic_match_dest(vcpu, NULL, 0, e->fields.dest_id,
                                e->fields.dest_mode))
                return;

        new_val = kvm_apic_pending_eoi(vcpu, e->fields.vector);
        old_val = test_bit(vcpu->vcpu_id, dest_map->map);

        if (new_val == old_val)
                return;

        if (new_val) {
                __set_bit(vcpu->vcpu_id, dest_map->map);
                dest_map->vectors[vcpu->vcpu_id] = e->fields.vector;
                ioapic->rtc_status.pending_eoi++;
        } else {
                __clear_bit(vcpu->vcpu_id, dest_map->map);
                ioapic->rtc_status.pending_eoi--;
                rtc_status_pending_eoi_check_valid(ioapic);
        }
}

void kvm_rtc_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
{
        struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;

        spin_lock(&ioapic->lock);
        __rtc_irq_eoi_tracking_restore_one(vcpu);
        spin_unlock(&ioapic->lock);
}

static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic)
{
        struct kvm_vcpu *vcpu;
        int i;

        if (RTC_GSI >= IOAPIC_NUM_PINS)
                return;

        rtc_irq_eoi_tracking_reset(ioapic);
        kvm_for_each_vcpu(i, vcpu, ioapic->kvm)
            __rtc_irq_eoi_tracking_restore_one(vcpu);
}

static void rtc_irq_eoi(struct kvm_ioapic *ioapic, struct kvm_vcpu *vcpu)
{
        if (test_and_clear_bit(vcpu->vcpu_id,
                               ioapic->rtc_status.dest_map.map)) {
                --ioapic->rtc_status.pending_eoi;
                rtc_status_pending_eoi_check_valid(ioapic);
        }
}

static bool rtc_irq_check_coalesced(struct kvm_ioapic *ioapic)
{
        if (ioapic->rtc_status.pending_eoi > 0)
                return true; /* coalesced */

        return false;
}

static int ioapic_set_irq(struct kvm_ioapic *ioapic, unsigned int irq,
                int irq_level, bool line_status)
{
        union kvm_ioapic_redirect_entry entry;
        u32 mask = 1 << irq;
        u32 old_irr;
        int edge, ret;

        entry = ioapic->redirtbl[irq];
        edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG);

        if (!irq_level) {
                ioapic->irr &= ~mask;
                ret = 1;
                goto out;
        }

        /*
         * Return 0 for coalesced interrupts; for edge-triggered interrupts,
         * this only happens if a previous edge has not been delivered due
         * do masking.  For level interrupts, the remote_irr field tells
         * us if the interrupt is waiting for an EOI.
         *
         * RTC is special: it is edge-triggered, but userspace likes to know
         * if it has been already ack-ed via EOI because coalesced RTC
         * interrupts lead to time drift in Windows guests.  So we track
         * EOI manually for the RTC interrupt.
         */
        if (irq == RTC_GSI && line_status &&
                rtc_irq_check_coalesced(ioapic)) {
                ret = 0;
                goto out;
        }

        old_irr = ioapic->irr;
        ioapic->irr |= mask;
        if (edge) {
                ioapic->irr_delivered &= ~mask;
                if (old_irr == ioapic->irr) {
                        ret = 0;
                        goto out;
                }
        }

        ret = ioapic_service(ioapic, irq, line_status);

out:
        trace_kvm_ioapic_set_irq(entry.bits, irq, ret == 0);
        return ret;
}

static void kvm_ioapic_inject_all(struct kvm_ioapic *ioapic, unsigned long irr)
{
        u32 idx;

        rtc_irq_eoi_tracking_reset(ioapic);
        for_each_set_bit(idx, &irr, IOAPIC_NUM_PINS)
                ioapic_set_irq(ioapic, idx, 1, true);

        kvm_rtc_eoi_tracking_restore_all(ioapic);
}


void kvm_ioapic_scan_entry(struct kvm_vcpu *vcpu, ulong *ioapic_handled_vectors)
{
        struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
        struct dest_map *dest_map = &ioapic->rtc_status.dest_map;
        union kvm_ioapic_redirect_entry *e;
        int index;

        spin_lock(&ioapic->lock);

        /* Make sure we see any missing RTC EOI */
        if (test_bit(vcpu->vcpu_id, dest_map->map))
                __set_bit(dest_map->vectors[vcpu->vcpu_id],
                          ioapic_handled_vectors);

        for (index = 0; index < IOAPIC_NUM_PINS; index++) {
                e = &ioapic->redirtbl[index];
                if (e->fields.trig_mode == IOAPIC_LEVEL_TRIG ||
                    kvm_irq_has_notifier(ioapic->kvm, KVM_IRQCHIP_IOAPIC, index) ||
                    index == RTC_GSI) {
                        if (kvm_apic_match_dest(vcpu, NULL, 0,
                                     e->fields.dest_id, e->fields.dest_mode) ||
                            kvm_apic_pending_eoi(vcpu, e->fields.vector))
                                __set_bit(e->fields.vector,
                                          ioapic_handled_vectors);
                }
        }
        spin_unlock(&ioapic->lock);
}

void kvm_arch_post_irq_ack_notifier_list_update(struct kvm *kvm)
{
        if (!ioapic_in_kernel(kvm))
                return;
        kvm_make_scan_ioapic_request(kvm);
}

static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
{
        unsigned index;
        bool mask_before, mask_after;
        int old_remote_irr, old_delivery_status;
        union kvm_ioapic_redirect_entry *e;

        switch (ioapic->ioregsel) {
        case IOAPIC_REG_VERSION:
                /* Writes are ignored. */
                break;

        case IOAPIC_REG_APIC_ID:
                ioapic->id = (val >> 24) & 0xf;
                break;

        case IOAPIC_REG_ARB_ID:
                break;

        default:
                index = (ioapic->ioregsel - 0x10) >> 1;

                if (index >= IOAPIC_NUM_PINS)
                        return;
                e = &ioapic->redirtbl[index];
                mask_before = e->fields.mask;
                /* Preserve read-only fields */
                old_remote_irr = e->fields.remote_irr;
                old_delivery_status = e->fields.delivery_status;
                if (ioapic->ioregsel & 1) {
                        e->bits &= 0xffffffff;
                        e->bits |= (u64) val << 32;
                } else {
                        e->bits &= ~0xffffffffULL;
                        e->bits |= (u32) val;
                }
                e->fields.remote_irr = old_remote_irr;
                e->fields.delivery_status = old_delivery_status;

                /*
                 * Some OSes (Linux, Xen) assume that Remote IRR bit will
                 * be cleared by IOAPIC hardware when the entry is configured
                 * as edge-triggered. This behavior is used to simulate an
                 * explicit EOI on IOAPICs that don't have the EOI register.
                 */
                if (e->fields.trig_mode == IOAPIC_EDGE_TRIG)
                        e->fields.remote_irr = 0;

                mask_after = e->fields.mask;
                if (mask_before != mask_after)
                        kvm_fire_mask_notifiers(ioapic->kvm, KVM_IRQCHIP_IOAPIC, index, mask_after);
                if (e->fields.trig_mode == IOAPIC_LEVEL_TRIG
                    && ioapic->irr & (1 << index))
                        ioapic_service(ioapic, index, false);
                kvm_make_scan_ioapic_request(ioapic->kvm);
                break;
        }
}

static int ioapic_service(struct kvm_ioapic *ioapic, int irq, bool line_status)
{
        union kvm_ioapic_redirect_entry *entry = &ioapic->redirtbl[irq];
        struct kvm_lapic_irq irqe;
        int ret;

        if (entry->fields.mask ||
            (entry->fields.trig_mode == IOAPIC_LEVEL_TRIG &&
            entry->fields.remote_irr))
                return -1;

        irqe.dest_id = entry->fields.dest_id;
        irqe.vector = entry->fields.vector;
        irqe.dest_mode = entry->fields.dest_mode;
        irqe.trig_mode = entry->fields.trig_mode;
        irqe.delivery_mode = entry->fields.delivery_mode << 8;
        irqe.level = 1;
        irqe.shorthand = 0;
        irqe.msi_redir_hint = false;

        if (irqe.trig_mode == IOAPIC_EDGE_TRIG)
                ioapic->irr_delivered |= 1 << irq;

        if (irq == RTC_GSI && line_status) {
                /*
                 * pending_eoi cannot ever become negative (see
                 * rtc_status_pending_eoi_check_valid) and the caller
                 * ensures that it is only called if it is >= zero, namely
                 * if rtc_irq_check_coalesced returns false).
                 */
                BUG_ON(ioapic->rtc_status.pending_eoi != 0);
                ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe,
                                               &ioapic->rtc_status.dest_map);
                ioapic->rtc_status.pending_eoi = (ret < 0 ? 0 : ret);
        } else
                ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe, NULL);

        if (ret && irqe.trig_mode == IOAPIC_LEVEL_TRIG)
                entry->fields.remote_irr = 1;

        return ret;
}

int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_source_id,
                       int level, bool line_status)
{
        int ret, irq_level;

        BUG_ON(irq < 0 || irq >= IOAPIC_NUM_PINS);

        spin_lock(&ioapic->lock);
        irq_level = __kvm_irq_line_state(&ioapic->irq_states[irq],
                                         irq_source_id, level);
        ret = ioapic_set_irq(ioapic, irq, irq_level, line_status);

        spin_unlock(&ioapic->lock);

        return ret;
}

void kvm_ioapic_clear_all(struct kvm_ioapic *ioapic, int irq_source_id)
{
        int i;

        spin_lock(&ioapic->lock);
        for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++)
                __clear_bit(irq_source_id, &ioapic->irq_states[i]);
        spin_unlock(&ioapic->lock);
}

static void kvm_ioapic_eoi_inject_work(struct work_struct *work)
{
        int i;
        struct kvm_ioapic *ioapic = container_of(work, struct kvm_ioapic,
                                                 eoi_inject.work);
        spin_lock(&ioapic->lock);
        for (i = 0; i < IOAPIC_NUM_PINS; i++) {
                union kvm_ioapic_redirect_entry *ent = &ioapic->redirtbl[i];

                if (ent->fields.trig_mode != IOAPIC_LEVEL_TRIG)
                        continue;

                if (ioapic->irr & (1 << i) && !ent->fields.remote_irr)
                        ioapic_service(ioapic, i, false);
        }
        spin_unlock(&ioapic->lock);
}

#define IOAPIC_SUCCESSIVE_IRQ_MAX_COUNT 10000

static void __kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu,
                        struct kvm_ioapic *ioapic, int vector, int trigger_mode)
{
        struct dest_map *dest_map = &ioapic->rtc_status.dest_map;
        struct kvm_lapic *apic = vcpu->arch.apic;
        int i;

        /* RTC special handling */
        if (test_bit(vcpu->vcpu_id, dest_map->map) &&
            vector == dest_map->vectors[vcpu->vcpu_id])
                rtc_irq_eoi(ioapic, vcpu);

        for (i = 0; i < IOAPIC_NUM_PINS; i++) {
                union kvm_ioapic_redirect_entry *ent = &ioapic->redirtbl[i];

                if (ent->fields.vector != vector)
                        continue;

                /*
                 * We are dropping lock while calling ack notifiers because ack
                 * notifier callbacks for assigned devices call into IOAPIC
                 * recursively. Since remote_irr is cleared only after call
                 * to notifiers if the same vector will be delivered while lock
                 * is dropped it will be put into irr and will be delivered
                 * after ack notifier returns.
                 */
                spin_unlock(&ioapic->lock);
                kvm_notify_acked_irq(ioapic->kvm, KVM_IRQCHIP_IOAPIC, i);
                spin_lock(&ioapic->lock);

                if (trigger_mode != IOAPIC_LEVEL_TRIG ||
                    kvm_lapic_get_reg(apic, APIC_SPIV) & APIC_SPIV_DIRECTED_EOI)
                        continue;

                ASSERT(ent->fields.trig_mode == IOAPIC_LEVEL_TRIG);
                ent->fields.remote_irr = 0;
                if (!ent->fields.mask && (ioapic->irr & (1 << i))) {
                        ++ioapic->irq_eoi[i];
                        if (ioapic->irq_eoi[i] == IOAPIC_SUCCESSIVE_IRQ_MAX_COUNT) {
                                /*
                                 * Real hardware does not deliver the interrupt
                                 * immediately during eoi broadcast, and this
                                 * lets a buggy guest make slow progress
                                 * even if it does not correctly handle a
                                 * level-triggered interrupt.  Emulate this
                                 * behavior if we detect an interrupt storm.
                                 */
                                schedule_delayed_work(&ioapic->eoi_inject, HZ / 100);
                                ioapic->irq_eoi[i] = 0;
                                trace_kvm_ioapic_delayed_eoi_inj(ent->bits);
                        } else {
                                ioapic_service(ioapic, i, false);
                        }
                } else {
                        ioapic->irq_eoi[i] = 0;
                }
        }
}

void kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu, int vector, int trigger_mode)
{
        struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;

        spin_lock(&ioapic->lock);
        __kvm_ioapic_update_eoi(vcpu, ioapic, vector, trigger_mode);
        spin_unlock(&ioapic->lock);
}

static inline struct kvm_ioapic *to_ioapic(struct kvm_io_device *dev)
{
        return container_of(dev, struct kvm_ioapic, dev);
}

static inline int ioapic_in_range(struct kvm_ioapic *ioapic, gpa_t addr)
{
        return ((addr >= ioapic->base_address &&
                 (addr < ioapic->base_address + IOAPIC_MEM_LENGTH)));
}

static int ioapic_mmio_read(struct kvm_vcpu *vcpu, struct kvm_io_device *this,
                                gpa_t addr, int len, void *val)
{
        struct kvm_ioapic *ioapic = to_ioapic(this);
        u32 result;
        if (!ioapic_in_range(ioapic, addr))
                return -EOPNOTSUPP;

        ASSERT(!(addr & 0xf));  /* check alignment */

        addr &= 0xff;
        spin_lock(&ioapic->lock);
        switch (addr) {
        case IOAPIC_REG_SELECT:
                result = ioapic->ioregsel;
                break;

        case IOAPIC_REG_WINDOW:
                result = ioapic_read_indirect(ioapic, addr, len);
                break;

        default:
                result = 0;
                break;
        }
        spin_unlock(&ioapic->lock);

        switch (len) {
        case 8:
                *(u64 *) val = result;
                break;
        case 1:
        case 2:
        case 4:
                memcpy(val, (char *)&result, len);
                break;
        default:
                printk(KERN_WARNING "ioapic: wrong length %d\n", len);
        }
        return 0;
}

static int ioapic_mmio_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this,
                                 gpa_t addr, int len, const void *val)
{
        struct kvm_ioapic *ioapic = to_ioapic(this);
        u32 data;
        if (!ioapic_in_range(ioapic, addr))
                return -EOPNOTSUPP;

        ASSERT(!(addr & 0xf));  /* check alignment */

        switch (len) {
        case 8:
        case 4:
                data = *(u32 *) val;
                break;
        case 2:
                data = *(u16 *) val;
                break;
        case 1:
                data = *(u8  *) val;
                break;
        default:
                printk(KERN_WARNING "ioapic: Unsupported size %d\n", len);
                return 0;
        }

        addr &= 0xff;
        spin_lock(&ioapic->lock);
        switch (addr) {
        case IOAPIC_REG_SELECT:
                ioapic->ioregsel = data & 0xFF; /* 8-bit register */
                break;

        case IOAPIC_REG_WINDOW:
                ioapic_write_indirect(ioapic, data);
                break;

        default:
                break;
        }
        spin_unlock(&ioapic->lock);
        return 0;
}

static void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
{
        int i;

        cancel_delayed_work_sync(&ioapic->eoi_inject);
        for (i = 0; i < IOAPIC_NUM_PINS; i++)
                ioapic->redirtbl[i].fields.mask = 1;
        ioapic->base_address = IOAPIC_DEFAULT_BASE_ADDRESS;
        ioapic->ioregsel = 0;
        ioapic->irr = 0;
        ioapic->irr_delivered = 0;
        ioapic->id = 0;
        memset(ioapic->irq_eoi, 0x00, sizeof(ioapic->irq_eoi));
        rtc_irq_eoi_tracking_reset(ioapic);
}

static const struct kvm_io_device_ops ioapic_mmio_ops = {
        .read     = ioapic_mmio_read,
        .write    = ioapic_mmio_write,
};

int kvm_ioapic_init(struct kvm *kvm)
{
        struct kvm_ioapic *ioapic;
        int ret;

        ioapic = kzalloc(sizeof(struct kvm_ioapic), GFP_KERNEL_ACCOUNT);
        if (!ioapic)
                return -ENOMEM;
        spin_lock_init(&ioapic->lock);
        INIT_DELAYED_WORK(&ioapic->eoi_inject, kvm_ioapic_eoi_inject_work);
        kvm->arch.vioapic = ioapic;
        kvm_ioapic_reset(ioapic);
        kvm_iodevice_init(&ioapic->dev, &ioapic_mmio_ops);
        ioapic->kvm = kvm;
        mutex_lock(&kvm->slots_lock);
        ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, ioapic->base_address,
                                      IOAPIC_MEM_LENGTH, &ioapic->dev);
        mutex_unlock(&kvm->slots_lock);
        if (ret < 0) {
                kvm->arch.vioapic = NULL;
                kfree(ioapic);
        }

        return ret;
}

void kvm_ioapic_destroy(struct kvm *kvm)
{
        struct kvm_ioapic *ioapic = kvm->arch.vioapic;

        if (!ioapic)
                return;

        cancel_delayed_work_sync(&ioapic->eoi_inject);
        mutex_lock(&kvm->slots_lock);
        kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &ioapic->dev);
        mutex_unlock(&kvm->slots_lock);
        kvm->arch.vioapic = NULL;
        kfree(ioapic);
}

void kvm_get_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
{
        struct kvm_ioapic *ioapic = kvm->arch.vioapic;

        spin_lock(&ioapic->lock);
        memcpy(state, ioapic, sizeof(struct kvm_ioapic_state));
        state->irr &= ~ioapic->irr_delivered;
        spin_unlock(&ioapic->lock);
}

void kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
{
        struct kvm_ioapic *ioapic = kvm->arch.vioapic;

        spin_lock(&ioapic->lock);
        memcpy(ioapic, state, sizeof(struct kvm_ioapic_state));
        ioapic->irr = 0;
        ioapic->irr_delivered = 0;
        kvm_make_scan_ioapic_request(kvm);
        kvm_ioapic_inject_all(ioapic, state->irr);
        spin_unlock(&ioapic->lock);
}