/*
 * irqchip.c: Common API for in kernel interrupt controllers
 * Copyright (c) 2007, Intel Corporation.
 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
 * Copyright (c) 2013, Alexander Graf <agraf@suse.de>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * This file is derived from virt/kvm/irq_comm.c.
 *
 * Authors:
 *   Yaozu (Eddie) Dong <Eddie.dong@intel.com>
 *   Alexander Graf <agraf@suse.de>
 */

#include <linux/kvm_host.h>
#include <linux/slab.h>
#include <linux/srcu.h>
#include <linux/export.h>
#include <trace/events/kvm.h>
#include "irq.h"

struct kvm_irq_routing_table {
        int chip[KVM_NR_IRQCHIPS][KVM_IRQCHIP_NUM_PINS];
        u32 nr_rt_entries;
        /*
         * Array indexed by gsi. Each entry contains list of irq chips
         * the gsi is connected to.
         */
        struct hlist_head map[0];
};

int kvm_irq_map_gsi(struct kvm *kvm,
                    struct kvm_kernel_irq_routing_entry *entries, int gsi)
{
        struct kvm_irq_routing_table *irq_rt;
        struct kvm_kernel_irq_routing_entry *e;
        int n = 0;

        irq_rt = srcu_dereference_check(kvm->irq_routing, &kvm->irq_srcu,
                                        lockdep_is_held(&kvm->irq_lock));
        if (gsi < irq_rt->nr_rt_entries) {
                hlist_for_each_entry(e, &irq_rt->map[gsi], link) {
                        entries[n] = *e;
                        ++n;
                }
        }

        return n;
}

int kvm_irq_map_chip_pin(struct kvm *kvm, unsigned irqchip, unsigned pin)
{
        struct kvm_irq_routing_table *irq_rt;

        irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
        return irq_rt->chip[irqchip][pin];
}

int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi)
{
        struct kvm_kernel_irq_routing_entry route;

        if (!irqchip_in_kernel(kvm) || msi->flags != 0)
                return -EINVAL;

        route.msi.address_lo = msi->address_lo;
        route.msi.address_hi = msi->address_hi;
        route.msi.data = msi->data;

        return kvm_set_msi(&route, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1, false);
}

/*
 * Return value:
 *  < 0   Interrupt was ignored (masked or not delivered for other reasons)
 *  = 0   Interrupt was coalesced (previous irq is still pending)
 *  > 0   Number of CPUs interrupt was delivered to
 */
int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level,
                bool line_status)
{
        struct kvm_kernel_irq_routing_entry irq_set[KVM_NR_IRQCHIPS];
        int ret = -1, i, idx;

        trace_kvm_set_irq(irq, level, irq_source_id);

        /* Not possible to detect if the guest uses the PIC or the
         * IOAPIC.  So set the bit in both. The guest will ignore
         * writes to the unused one.
         */
        idx = srcu_read_lock(&kvm->irq_srcu);
        i = kvm_irq_map_gsi(kvm, irq_set, irq);
        srcu_read_unlock(&kvm->irq_srcu, idx);

        while (i--) {
                int r;
                r = irq_set[i].set(&irq_set[i], kvm, irq_source_id, level,
                                   line_status);
                if (r < 0)
                        continue;

                ret = r + ((ret < 0) ? 0 : ret);
        }

        return ret;
}

static void free_irq_routing_table(struct kvm_irq_routing_table *rt)
{
        int i;

        if (!rt)
                return;

        for (i = 0; i < rt->nr_rt_entries; ++i) {
                struct kvm_kernel_irq_routing_entry *e;
                struct hlist_node *n;

                hlist_for_each_entry_safe(e, n, &rt->map[i], link) {
                        hlist_del(&e->link);
                        kfree(e);
                }
        }

        kfree(rt);
}

void kvm_free_irq_routing(struct kvm *kvm)
{
        /* Called only during vm destruction. Nobody can use the pointer
           at this stage */
        struct kvm_irq_routing_table *rt = rcu_access_pointer(kvm->irq_routing);
        free_irq_routing_table(rt);
}

static int setup_routing_entry(struct kvm_irq_routing_table *rt,
                               struct kvm_kernel_irq_routing_entry *e,
                               const struct kvm_irq_routing_entry *ue)
{
        int r = -EINVAL;
        struct kvm_kernel_irq_routing_entry *ei;

        /*
         * Do not allow GSI to be mapped to the same irqchip more than once.
         * Allow only one to one mapping between GSI and MSI.
         */
        hlist_for_each_entry(ei, &rt->map[ue->gsi], link)
                if (ei->type == KVM_IRQ_ROUTING_MSI ||
                    ue->type == KVM_IRQ_ROUTING_MSI ||
                    ue->u.irqchip.irqchip == ei->irqchip.irqchip)
                        return r;

        e->gsi = ue->gsi;
        e->type = ue->type;
        r = kvm_set_routing_entry(e, ue);
        if (r)
                goto out;
        if (e->type == KVM_IRQ_ROUTING_IRQCHIP)
                rt->chip[e->irqchip.irqchip][e->irqchip.pin] = e->gsi;

        hlist_add_head(&e->link, &rt->map[e->gsi]);
        r = 0;
out:
        return r;
}

int kvm_set_irq_routing(struct kvm *kvm,
                        const struct kvm_irq_routing_entry *ue,
                        unsigned nr,
                        unsigned flags)
{
        struct kvm_irq_routing_table *new, *old;
        u32 i, j, nr_rt_entries = 0;
        int r;

        for (i = 0; i < nr; ++i) {
                if (ue[i].gsi >= KVM_MAX_IRQ_ROUTES)
                        return -EINVAL;
                nr_rt_entries = max(nr_rt_entries, ue[i].gsi);
        }

        nr_rt_entries += 1;

        new = kzalloc(sizeof(*new) + (nr_rt_entries * sizeof(struct hlist_head)),
                      GFP_KERNEL);

        if (!new)
                return -ENOMEM;

        new->nr_rt_entries = nr_rt_entries;
        for (i = 0; i < KVM_NR_IRQCHIPS; i++)
                for (j = 0; j < KVM_IRQCHIP_NUM_PINS; j++)
                        new->chip[i][j] = -1;

        for (i = 0; i < nr; ++i) {
                struct kvm_kernel_irq_routing_entry *e;

                r = -ENOMEM;
                e = kzalloc(sizeof(*e), GFP_KERNEL);
                if (!e)
                        goto out;

                r = -EINVAL;
                if (ue->flags)
                        goto out;
                r = setup_routing_entry(new, e, ue);
                if (r)
                        goto out;
                ++ue;
        }

        mutex_lock(&kvm->irq_lock);
        old = kvm->irq_routing;
        rcu_assign_pointer(kvm->irq_routing, new);
        kvm_irq_routing_update(kvm);
        mutex_unlock(&kvm->irq_lock);

        synchronize_srcu_expedited(&kvm->irq_srcu);

        new = old;
        r = 0;

out:
        free_irq_routing_table(new);

        return r;
}