// SPDX-License-Identifier: GPL-2.0-only
/*
 * VFIO-KVM bridge pseudo device
 *
 * Copyright (C) 2013 Red Hat, Inc.  All rights reserved.
 *     Author: Alex Williamson <alex.williamson@redhat.com>
 */

#include <linux/errno.h>
#include <linux/file.h>
#include <linux/kvm_host.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/vfio.h>
#include "vfio.h"

#ifdef CONFIG_SPAPR_TCE_IOMMU
#include <asm/kvm_ppc.h>
#endif

struct kvm_vfio_file {
        struct list_head node;
        struct file *file;
#ifdef CONFIG_SPAPR_TCE_IOMMU
        struct iommu_group *iommu_group;
#endif
};

struct kvm_vfio {
        struct list_head file_list;
        struct mutex lock;
        bool noncoherent;
};

static void kvm_vfio_file_set_kvm(struct file *file, struct kvm *kvm)
{
        void (*fn)(struct file *file, struct kvm *kvm);

        fn = symbol_get(vfio_file_set_kvm);
        if (!fn)
                return;

        fn(file, kvm);

        symbol_put(vfio_file_set_kvm);
}

static bool kvm_vfio_file_enforced_coherent(struct file *file)
{
        bool (*fn)(struct file *file);
        bool ret;

        fn = symbol_get(vfio_file_enforced_coherent);
        if (!fn)
                return false;

        ret = fn(file);

        symbol_put(vfio_file_enforced_coherent);

        return ret;
}

static bool kvm_vfio_file_is_valid(struct file *file)
{
        bool (*fn)(struct file *file);
        bool ret;

        fn = symbol_get(vfio_file_is_valid);
        if (!fn)
                return false;

        ret = fn(file);

        symbol_put(vfio_file_is_valid);

        return ret;
}

#ifdef CONFIG_SPAPR_TCE_IOMMU
static struct iommu_group *kvm_vfio_file_iommu_group(struct file *file)
{
        struct iommu_group *(*fn)(struct file *file);
        struct iommu_group *ret;

        fn = symbol_get(vfio_file_iommu_group);
        if (!fn)
                return NULL;

        ret = fn(file);

        symbol_put(vfio_file_iommu_group);

        return ret;
}

static void kvm_spapr_tce_release_vfio_group(struct kvm *kvm,
                                             struct kvm_vfio_file *kvf)
{
        if (WARN_ON_ONCE(!kvf->iommu_group))
                return;

        kvm_spapr_tce_release_iommu_group(kvm, kvf->iommu_group);
        iommu_group_put(kvf->iommu_group);
        kvf->iommu_group = NULL;
}
#endif

/*
 * Groups/devices can use the same or different IOMMU domains. If the same
 * then adding a new group/device may change the coherency of groups/devices
 * we've previously been told about. We don't want to care about any of
 * that so we retest each group/device and bail as soon as we find one that's
 * noncoherent.  This means we only ever [un]register_noncoherent_dma once
 * for the whole device.
 */
static void kvm_vfio_update_coherency(struct kvm_device *dev)
{
        struct kvm_vfio *kv = dev->private;
        bool noncoherent = false;
        struct kvm_vfio_file *kvf;

        list_for_each_entry(kvf, &kv->file_list, node) {
                if (!kvm_vfio_file_enforced_coherent(kvf->file)) {
                        noncoherent = true;
                        break;
                }
        }

        if (noncoherent != kv->noncoherent) {
                kv->noncoherent = noncoherent;

                if (kv->noncoherent)
                        kvm_arch_register_noncoherent_dma(dev->kvm);
                else
                        kvm_arch_unregister_noncoherent_dma(dev->kvm);
        }
}

static int kvm_vfio_file_add(struct kvm_device *dev, unsigned int fd)
{
        struct kvm_vfio *kv = dev->private;
        struct kvm_vfio_file *kvf;
        struct file *filp;
        int ret = 0;

        filp = fget(fd);
        if (!filp)
                return -EBADF;

        /* Ensure the FD is a vfio FD. */
        if (!kvm_vfio_file_is_valid(filp)) {
                ret = -EINVAL;
                goto out_fput;
        }

        mutex_lock(&kv->lock);

        list_for_each_entry(kvf, &kv->file_list, node) {
                if (kvf->file == filp) {
                        ret = -EEXIST;
                        goto out_unlock;
                }
        }

        kvf = kzalloc_obj(*kvf, GFP_KERNEL_ACCOUNT);
        if (!kvf) {
                ret = -ENOMEM;
                goto out_unlock;
        }

        kvf->file = get_file(filp);
        list_add_tail(&kvf->node, &kv->file_list);

        kvm_vfio_file_set_kvm(kvf->file, dev->kvm);
        kvm_vfio_update_coherency(dev);

out_unlock:
        mutex_unlock(&kv->lock);
out_fput:
        fput(filp);
        return ret;
}

static int kvm_vfio_file_del(struct kvm_device *dev, unsigned int fd)
{
        struct kvm_vfio *kv = dev->private;
        struct kvm_vfio_file *kvf;
        CLASS(fd, f)(fd);
        int ret;

        if (fd_empty(f))
                return -EBADF;

        ret = -ENOENT;

        mutex_lock(&kv->lock);

        list_for_each_entry(kvf, &kv->file_list, node) {
                if (kvf->file != fd_file(f))
                        continue;

                list_del(&kvf->node);
#ifdef CONFIG_SPAPR_TCE_IOMMU
                kvm_spapr_tce_release_vfio_group(dev->kvm, kvf);
#endif
                kvm_vfio_file_set_kvm(kvf->file, NULL);
                fput(kvf->file);
                kfree(kvf);
                ret = 0;
                break;
        }

        kvm_vfio_update_coherency(dev);

        mutex_unlock(&kv->lock);
        return ret;
}

#ifdef CONFIG_SPAPR_TCE_IOMMU
static int kvm_vfio_file_set_spapr_tce(struct kvm_device *dev,
                                       void __user *arg)
{
        struct kvm_vfio_spapr_tce param;
        struct kvm_vfio *kv = dev->private;
        struct kvm_vfio_file *kvf;
        int ret;

        if (copy_from_user(&param, arg, sizeof(struct kvm_vfio_spapr_tce)))
                return -EFAULT;

        CLASS(fd, f)(param.groupfd);
        if (fd_empty(f))
                return -EBADF;

        ret = -ENOENT;

        mutex_lock(&kv->lock);

        list_for_each_entry(kvf, &kv->file_list, node) {
                if (kvf->file != fd_file(f))
                        continue;

                if (!kvf->iommu_group) {
                        kvf->iommu_group = kvm_vfio_file_iommu_group(kvf->file);
                        if (WARN_ON_ONCE(!kvf->iommu_group)) {
                                ret = -EIO;
                                goto err_fdput;
                        }
                }

                ret = kvm_spapr_tce_attach_iommu_group(dev->kvm, param.tablefd,
                                                       kvf->iommu_group);
                break;
        }

err_fdput:
        mutex_unlock(&kv->lock);
        return ret;
}
#endif

static int kvm_vfio_set_file(struct kvm_device *dev, long attr,
                             void __user *arg)
{
        int32_t __user *argp = arg;
        int32_t fd;

        switch (attr) {
        case KVM_DEV_VFIO_FILE_ADD:
                if (get_user(fd, argp))
                        return -EFAULT;
                return kvm_vfio_file_add(dev, fd);

        case KVM_DEV_VFIO_FILE_DEL:
                if (get_user(fd, argp))
                        return -EFAULT;
                return kvm_vfio_file_del(dev, fd);

#ifdef CONFIG_SPAPR_TCE_IOMMU
        case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
                return kvm_vfio_file_set_spapr_tce(dev, arg);
#endif
        }

        return -ENXIO;
}

static int kvm_vfio_set_attr(struct kvm_device *dev,
                             struct kvm_device_attr *attr)
{
        switch (attr->group) {
        case KVM_DEV_VFIO_FILE:
                return kvm_vfio_set_file(dev, attr->attr,
                                         u64_to_user_ptr(attr->addr));
        }

        return -ENXIO;
}

static int kvm_vfio_has_attr(struct kvm_device *dev,
                             struct kvm_device_attr *attr)
{
        switch (attr->group) {
        case KVM_DEV_VFIO_FILE:
                switch (attr->attr) {
                case KVM_DEV_VFIO_FILE_ADD:
                case KVM_DEV_VFIO_FILE_DEL:
#ifdef CONFIG_SPAPR_TCE_IOMMU
                case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
#endif
                        return 0;
                }

                break;
        }

        return -ENXIO;
}

static void kvm_vfio_release(struct kvm_device *dev)
{
        struct kvm_vfio *kv = dev->private;
        struct kvm_vfio_file *kvf, *tmp;

        list_for_each_entry_safe(kvf, tmp, &kv->file_list, node) {
#ifdef CONFIG_SPAPR_TCE_IOMMU
                kvm_spapr_tce_release_vfio_group(dev->kvm, kvf);
#endif
                kvm_vfio_file_set_kvm(kvf->file, NULL);
                fput(kvf->file);
                list_del(&kvf->node);
                kfree(kvf);
        }

        kvm_vfio_update_coherency(dev);

        kfree(kv);
        kfree(dev); /* alloc by kvm_ioctl_create_device, free by .release */
}

static int kvm_vfio_create(struct kvm_device *dev, u32 type);

static const struct kvm_device_ops kvm_vfio_ops = {
        .name = "kvm-vfio",
        .create = kvm_vfio_create,
        .release = kvm_vfio_release,
        .set_attr = kvm_vfio_set_attr,
        .has_attr = kvm_vfio_has_attr,
};

static int kvm_vfio_create(struct kvm_device *dev, u32 type)
{
        struct kvm_device *tmp;
        struct kvm_vfio *kv;

        lockdep_assert_held(&dev->kvm->lock);

        /* Only one VFIO "device" per VM */
        list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
                if (tmp->ops == &kvm_vfio_ops)
                        return -EBUSY;

        kv = kzalloc_obj(*kv, GFP_KERNEL_ACCOUNT);
        if (!kv)
                return -ENOMEM;

        INIT_LIST_HEAD(&kv->file_list);
        mutex_init(&kv->lock);

        dev->private = kv;

        return 0;
}

int kvm_vfio_ops_init(void)
{
        return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
}

void kvm_vfio_ops_exit(void)
{
        kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
}