// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2016 Linaro
 * Author: Christoffer Dall <christoffer.dall@linaro.org>
 */

#include <linux/cpu.h>
#include <linux/debugfs.h>
#include <linux/interrupt.h>
#include <linux/kvm_host.h>
#include <linux/seq_file.h>
#include <kvm/arm_vgic.h>
#include <asm/kvm_mmu.h>
#include "vgic.h"

/*
 * Structure to control looping through the entire vgic state.  We start at
 * zero for each field and move upwards.  So, if dist_id is 0 we print the
 * distributor info.  When dist_id is 1, we have already printed it and move
 * on.
 *
 * When vcpu_id < nr_cpus we print the vcpu info until vcpu_id == nr_cpus and
 * so on.
 */
struct vgic_state_iter {
        int nr_cpus;
        int nr_spis;
        int dist_id;
        int vcpu_id;
        unsigned long intid;
};

static void iter_next(struct kvm *kvm, struct vgic_state_iter *iter)
{
        struct vgic_dist *dist = &kvm->arch.vgic;

        if (iter->dist_id == 0) {
                iter->dist_id++;
                return;
        }

        /*
         * Let the xarray drive the iterator after the last SPI, as the iterator
         * has exhausted the sequentially-allocated INTID space.
         */
        if (iter->intid >= (iter->nr_spis + VGIC_NR_PRIVATE_IRQS - 1)) {
                if (iter->intid == VGIC_LPI_MAX_INTID + 1)
                        return;

                rcu_read_lock();
                if (!xa_find_after(&dist->lpi_xa, &iter->intid,
                                   VGIC_LPI_MAX_INTID, XA_PRESENT))
                        iter->intid = VGIC_LPI_MAX_INTID + 1;
                rcu_read_unlock();
                return;
        }

        iter->intid++;
        if (iter->intid == VGIC_NR_PRIVATE_IRQS &&
            ++iter->vcpu_id < iter->nr_cpus)
                iter->intid = 0;
}

static int vgic_count_lpis(struct kvm *kvm)
{
        struct vgic_dist *dist = &kvm->arch.vgic;
        struct vgic_irq *irq;
        unsigned long intid;
        int nr_lpis = 0;

        rcu_read_lock();
        xa_for_each(&dist->lpi_xa, intid, irq)
                nr_lpis++;
        rcu_read_unlock();

        return nr_lpis;
}

static void iter_init(struct kvm *kvm, struct vgic_state_iter *iter,
                      loff_t pos)
{
        int nr_cpus = atomic_read(&kvm->online_vcpus);

        memset(iter, 0, sizeof(*iter));

        iter->nr_cpus = nr_cpus;
        iter->nr_spis = kvm->arch.vgic.nr_spis;

        /* Fast forward to the right position if needed */
        while (pos--)
                iter_next(kvm, iter);
}

static bool end_of_vgic(struct vgic_state_iter *iter)
{
        return iter->dist_id > 0 &&
                iter->vcpu_id == iter->nr_cpus &&
                iter->intid >= (iter->nr_spis + VGIC_NR_PRIVATE_IRQS) &&
                iter->intid > VGIC_LPI_MAX_INTID;
}

static void *vgic_debug_start(struct seq_file *s, loff_t *pos)
{
        struct kvm *kvm = s->private;
        struct vgic_state_iter *iter;

        iter = kmalloc_obj(*iter);
        if (!iter)
                return ERR_PTR(-ENOMEM);

        iter_init(kvm, iter, *pos);

        if (end_of_vgic(iter)) {
                kfree(iter);
                iter = NULL;
        }

        return iter;
}

static void *vgic_debug_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct kvm *kvm = s->private;
        struct vgic_state_iter *iter = v;

        ++*pos;
        iter_next(kvm, iter);
        if (end_of_vgic(iter)) {
                kfree(iter);
                iter = NULL;
        }
        return iter;
}

static void vgic_debug_stop(struct seq_file *s, void *v)
{
        struct vgic_state_iter *iter = v;

        if (IS_ERR_OR_NULL(v))
                return;

        kfree(iter);
}

static void print_dist_state(struct seq_file *s, struct vgic_dist *dist,
                             struct vgic_state_iter *iter)
{
        bool v3 = dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3;
        struct kvm *kvm = s->private;

        seq_printf(s, "Distributor\n");
        seq_printf(s, "===========\n");
        seq_printf(s, "vgic_model:\t%s\n", v3 ? "GICv3" : "GICv2");
        seq_printf(s, "nr_spis:\t%d\n", dist->nr_spis);
        if (v3)
                seq_printf(s, "nr_lpis:\t%d\n", vgic_count_lpis(kvm));
        seq_printf(s, "enabled:\t%d\n", dist->enabled);
        seq_printf(s, "\n");

        seq_printf(s, "P=pending_latch, L=line_level, A=active\n");
        seq_printf(s, "E=enabled, H=hw, C=config (level=1, edge=0)\n");
        seq_printf(s, "G=group\n");
}

static void print_header(struct seq_file *s, struct vgic_irq *irq,
                         struct kvm_vcpu *vcpu)
{
        int id = 0;
        char *hdr = "SPI ";

        if (vcpu) {
                hdr = "VCPU";
                id = vcpu->vcpu_idx;
        }

        seq_printf(s, "\n");
        seq_printf(s, "%s%2d TYP   ID TGT_ID PLAEHCG     HWID   TARGET SRC PRI VCPU_ID\n", hdr, id);
        seq_printf(s, "----------------------------------------------------------------\n");
}

static void print_irq_state(struct seq_file *s, struct vgic_irq *irq,
                            struct kvm_vcpu *vcpu)
{
        char *type;
        bool pending;

        if (irq->intid < VGIC_NR_SGIS)
                type = "SGI";
        else if (irq->intid < VGIC_NR_PRIVATE_IRQS)
                type = "PPI";
        else if (irq->intid < VGIC_MAX_SPI)
                type = "SPI";
        else
                type = "LPI";

        if (irq->intid ==0 || irq->intid == VGIC_NR_PRIVATE_IRQS)
                print_header(s, irq, vcpu);

        pending = irq->pending_latch;
        if (irq->hw && vgic_irq_is_sgi(irq->intid)) {
                int err;

                err = irq_get_irqchip_state(irq->host_irq,
                                            IRQCHIP_STATE_PENDING,
                                            &pending);
                WARN_ON_ONCE(err);
        }

        seq_printf(s, "       %s %4d "
                      "    %2d "
                      "%d%d%d%d%d%d%d "
                      "%8d "
                      "%8x "
                      " %2x "
                      "%3d "
                      "     %2d "
                      "\n",
                        type, irq->intid,
                        (irq->target_vcpu) ? irq->target_vcpu->vcpu_idx : -1,
                        pending,
                        irq->line_level,
                        irq->active,
                        irq->enabled,
                        irq->hw,
                        irq->config == VGIC_CONFIG_LEVEL,
                        irq->group,
                        irq->hwintid,
                        irq->mpidr,
                        irq->source,
                        irq->priority,
                        (irq->vcpu) ? irq->vcpu->vcpu_idx : -1);
}

static int vgic_debug_show(struct seq_file *s, void *v)
{
        struct kvm *kvm = s->private;
        struct vgic_state_iter *iter = v;
        struct vgic_irq *irq;
        struct kvm_vcpu *vcpu = NULL;
        unsigned long flags;

        if (iter->dist_id == 0) {
                print_dist_state(s, &kvm->arch.vgic, iter);
                return 0;
        }

        if (!kvm->arch.vgic.initialized)
                return 0;

        if (iter->vcpu_id < iter->nr_cpus)
                vcpu = kvm_get_vcpu(kvm, iter->vcpu_id);

        if (iter->intid < VGIC_NR_PRIVATE_IRQS)
                irq = vgic_get_vcpu_irq(vcpu, iter->intid);
        else
                irq = vgic_get_irq(kvm, iter->intid);

        if (!irq)
                return 0;

        raw_spin_lock_irqsave(&irq->irq_lock, flags);
        print_irq_state(s, irq, vcpu);
        raw_spin_unlock_irqrestore(&irq->irq_lock, flags);

        vgic_put_irq(kvm, irq);
        return 0;
}

static const struct seq_operations vgic_debug_sops = {
        .start = vgic_debug_start,
        .next  = vgic_debug_next,
        .stop  = vgic_debug_stop,
        .show  = vgic_debug_show
};

DEFINE_SEQ_ATTRIBUTE(vgic_debug);

void vgic_debug_init(struct kvm *kvm)
{
        debugfs_create_file("vgic-state", 0444, kvm->debugfs_dentry, kvm,
                            &vgic_debug_fops);
}

void vgic_debug_destroy(struct kvm *kvm)
{
}

/**
 * struct vgic_its_iter - Iterator for traversing VGIC ITS device tables.
 * @dev: Pointer to the current its_device being processed.
 * @ite: Pointer to the current its_ite within the device being processed.
 *
 * This structure is used to maintain the current position during iteration
 * over the ITS device tables. It holds pointers to both the current device
 * and the current ITE within that device.
 */
struct vgic_its_iter {
        struct its_device *dev;
        struct its_ite *ite;
};

/**
 * end_of_iter - Checks if the iterator has reached the end.
 * @iter: The iterator to check.
 *
 * When the iterator completed processing the final ITE in the last device
 * table, it was marked to indicate the end of iteration by setting its
 * device and ITE pointers to NULL.
 * This function checks whether the iterator was marked as end.
 *
 * Return: True if the iterator is marked as end, false otherwise.
 */
static inline bool end_of_iter(struct vgic_its_iter *iter)
{
        return !iter->dev && !iter->ite;
}

/**
 * vgic_its_iter_next - Advances the iterator to the next entry in the ITS tables.
 * @its: The VGIC ITS structure.
 * @iter: The iterator to advance.
 *
 * This function moves the iterator to the next ITE within the current device,
 * or to the first ITE of the next device if the current ITE is the last in
 * the device. If the current device is the last device, the iterator is set
 * to indicate the end of iteration.
 */
static void vgic_its_iter_next(struct vgic_its *its, struct vgic_its_iter *iter)
{
        struct its_device *dev = iter->dev;
        struct its_ite *ite = iter->ite;

        if (!ite || list_is_last(&ite->ite_list, &dev->itt_head)) {
                if (list_is_last(&dev->dev_list, &its->device_list)) {
                        dev = NULL;
                        ite = NULL;
                } else {
                        dev = list_next_entry(dev, dev_list);
                        ite = list_first_entry_or_null(&dev->itt_head,
                                                       struct its_ite,
                                                       ite_list);
                }
        } else {
                ite = list_next_entry(ite, ite_list);
        }

        iter->dev = dev;
        iter->ite = ite;
}

/**
 * vgic_its_debug_start - Start function for the seq_file interface.
 * @s: The seq_file structure.
 * @pos: The starting position (offset).
 *
 * This function initializes the iterator to the beginning of the ITS tables
 * and advances it to the specified position. It acquires the its_lock mutex
 * to protect shared data.
 *
 * Return: An iterator pointer on success, NULL if no devices are found or
 *         the end of the list is reached, or ERR_PTR(-ENOMEM) on memory
 *         allocation failure.
 */
static void *vgic_its_debug_start(struct seq_file *s, loff_t *pos)
{
        struct vgic_its *its = s->private;
        struct vgic_its_iter *iter;
        struct its_device *dev;
        loff_t offset = *pos;

        mutex_lock(&its->its_lock);

        dev = list_first_entry_or_null(&its->device_list,
                                       struct its_device, dev_list);
        if (!dev)
                return NULL;

        iter = kmalloc_obj(*iter);
        if (!iter)
                return ERR_PTR(-ENOMEM);

        iter->dev = dev;
        iter->ite = list_first_entry_or_null(&dev->itt_head,
                                             struct its_ite, ite_list);

        while (!end_of_iter(iter) && offset--)
                vgic_its_iter_next(its, iter);

        if (end_of_iter(iter)) {
                kfree(iter);
                return NULL;
        }

        return iter;
}

/**
 * vgic_its_debug_next - Next function for the seq_file interface.
 * @s: The seq_file structure.
 * @v: The current iterator.
 * @pos: The current position (offset).
 *
 * This function advances the iterator to the next entry and increments the
 * position.
 *
 * Return: An iterator pointer on success, or NULL if the end of the list is
 *         reached.
 */
static void *vgic_its_debug_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct vgic_its *its = s->private;
        struct vgic_its_iter *iter = v;

        ++*pos;
        vgic_its_iter_next(its, iter);

        if (end_of_iter(iter)) {
                kfree(iter);
                return NULL;
        }
        return iter;
}

/**
 * vgic_its_debug_stop - Stop function for the seq_file interface.
 * @s: The seq_file structure.
 * @v: The current iterator.
 *
 * This function frees the iterator and releases the its_lock mutex.
 */
static void vgic_its_debug_stop(struct seq_file *s, void *v)
{
        struct vgic_its *its = s->private;
        struct vgic_its_iter *iter = v;

        if (!IS_ERR_OR_NULL(iter))
                kfree(iter);
        mutex_unlock(&its->its_lock);
}

/**
 * vgic_its_debug_show - Show function for the seq_file interface.
 * @s: The seq_file structure.
 * @v: The current iterator.
 *
 * This function formats and prints the ITS table entry information to the
 * seq_file output.
 *
 * Return: 0 on success.
 */
static int vgic_its_debug_show(struct seq_file *s, void *v)
{
        struct vgic_its_iter *iter = v;
        struct its_device *dev = iter->dev;
        struct its_ite *ite = iter->ite;

        if (!ite)
                return 0;

        if (list_is_first(&ite->ite_list, &dev->itt_head)) {
                seq_printf(s, "\n");
                seq_printf(s, "Device ID: 0x%x, Event ID Range: [0 - %llu]\n",
                           dev->device_id, BIT_ULL(dev->num_eventid_bits) - 1);
                seq_printf(s, "EVENT_ID    INTID  HWINTID   TARGET   COL_ID HW\n");
                seq_printf(s, "-----------------------------------------------\n");
        }

        if (ite->irq && ite->collection) {
                seq_printf(s, "%8u %8u %8u %8u %8u %2d\n",
                           ite->event_id, ite->irq->intid, ite->irq->hwintid,
                           ite->collection->target_addr,
                           ite->collection->collection_id, ite->irq->hw);
        }

        return 0;
}

static const struct seq_operations vgic_its_debug_sops = {
        .start = vgic_its_debug_start,
        .next  = vgic_its_debug_next,
        .stop  = vgic_its_debug_stop,
        .show  = vgic_its_debug_show
};

DEFINE_SEQ_ATTRIBUTE(vgic_its_debug);

/**
 * vgic_its_debug_init - Initializes the debugfs interface for VGIC ITS.
 * @dev: The KVM device structure.
 *
 * This function creates a debugfs file named "vgic-its-state@%its_base"
 * to expose the ITS table information.
 *
 * Return: 0 on success.
 */
int vgic_its_debug_init(struct kvm_device *dev)
{
        struct vgic_its *its = dev->private;
        char *name;

        name = kasprintf(GFP_KERNEL, "vgic-its-state@%llx", (u64)its->vgic_its_base);
        if (!name)
                return -ENOMEM;

        debugfs_create_file(name, 0444, dev->kvm->debugfs_dentry, its, &vgic_its_debug_fops);

        kfree(name);
        return 0;
}

void vgic_its_debug_destroy(struct kvm_device *dev)
{
}