// SPDX-License-Identifier: GPL-2.0-only
/*
 * vDPA bus.
 *
 * Copyright (c) 2020, Red Hat. All rights reserved.
 *     Author: Jason Wang <jasowang@redhat.com>
 *
 */

#include <linux/module.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <linux/vdpa.h>
#include <uapi/linux/vdpa.h>
#include <net/genetlink.h>
#include <linux/mod_devicetable.h>

static LIST_HEAD(mdev_head);
/* A global mutex that protects vdpa management device and device level operations. */
static DEFINE_MUTEX(vdpa_dev_mutex);
static DEFINE_IDA(vdpa_index_ida);

static struct genl_family vdpa_nl_family;

static int vdpa_dev_probe(struct device *d)
{
        struct vdpa_device *vdev = dev_to_vdpa(d);
        struct vdpa_driver *drv = drv_to_vdpa(vdev->dev.driver);
        int ret = 0;

        if (drv && drv->probe)
                ret = drv->probe(vdev);

        return ret;
}

static int vdpa_dev_remove(struct device *d)
{
        struct vdpa_device *vdev = dev_to_vdpa(d);
        struct vdpa_driver *drv = drv_to_vdpa(vdev->dev.driver);

        if (drv && drv->remove)
                drv->remove(vdev);

        return 0;
}

static struct bus_type vdpa_bus = {
        .name  = "vdpa",
        .probe = vdpa_dev_probe,
        .remove = vdpa_dev_remove,
};

static void vdpa_release_dev(struct device *d)
{
        struct vdpa_device *vdev = dev_to_vdpa(d);
        const struct vdpa_config_ops *ops = vdev->config;

        if (ops->free)
                ops->free(vdev);

        ida_simple_remove(&vdpa_index_ida, vdev->index);
        kfree(vdev);
}

/**
 * __vdpa_alloc_device - allocate and initilaize a vDPA device
 * This allows driver to some prepartion after device is
 * initialized but before registered.
 * @parent: the parent device
 * @config: the bus operations that is supported by this device
 * @size: size of the parent structure that contains private data
 * @name: name of the vdpa device; optional.
 *
 * Driver should use vdpa_alloc_device() wrapper macro instead of
 * using this directly.
 *
 * Return: Returns an error when parent/config/dma_dev is not set or fail to get
 *         ida.
 */
struct vdpa_device *__vdpa_alloc_device(struct device *parent,
                                        const struct vdpa_config_ops *config,
                                        size_t size, const char *name)
{
        struct vdpa_device *vdev;
        int err = -EINVAL;

        if (!config)
                goto err;

        if (!!config->dma_map != !!config->dma_unmap)
                goto err;

        err = -ENOMEM;
        vdev = kzalloc(size, GFP_KERNEL);
        if (!vdev)
                goto err;

        err = ida_alloc(&vdpa_index_ida, GFP_KERNEL);
        if (err < 0)
                goto err_ida;

        vdev->dev.bus = &vdpa_bus;
        vdev->dev.parent = parent;
        vdev->dev.release = vdpa_release_dev;
        vdev->index = err;
        vdev->config = config;
        vdev->features_valid = false;

        if (name)
                err = dev_set_name(&vdev->dev, "%s", name);
        else
                err = dev_set_name(&vdev->dev, "vdpa%u", vdev->index);
        if (err)
                goto err_name;

        device_initialize(&vdev->dev);

        return vdev;

err_name:
        ida_simple_remove(&vdpa_index_ida, vdev->index);
err_ida:
        kfree(vdev);
err:
        return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(__vdpa_alloc_device);

static int vdpa_name_match(struct device *dev, const void *data)
{
        struct vdpa_device *vdev = container_of(dev, struct vdpa_device, dev);

        return (strcmp(dev_name(&vdev->dev), data) == 0);
}

static int __vdpa_register_device(struct vdpa_device *vdev, int nvqs)
{
        struct device *dev;

        vdev->nvqs = nvqs;

        lockdep_assert_held(&vdpa_dev_mutex);
        dev = bus_find_device(&vdpa_bus, NULL, dev_name(&vdev->dev), vdpa_name_match);
        if (dev) {
                put_device(dev);
                return -EEXIST;
        }
        return device_add(&vdev->dev);
}

/**
 * _vdpa_register_device - register a vDPA device with vdpa lock held
 * Caller must have a succeed call of vdpa_alloc_device() before.
 * Caller must invoke this routine in the management device dev_add()
 * callback after setting up valid mgmtdev for this vdpa device.
 * @vdev: the vdpa device to be registered to vDPA bus
 * @nvqs: number of virtqueues supported by this device
 *
 * Return: Returns an error when fail to add device to vDPA bus
 */
int _vdpa_register_device(struct vdpa_device *vdev, int nvqs)
{
        if (!vdev->mdev)
                return -EINVAL;

        return __vdpa_register_device(vdev, nvqs);
}
EXPORT_SYMBOL_GPL(_vdpa_register_device);

/**
 * vdpa_register_device - register a vDPA device
 * Callers must have a succeed call of vdpa_alloc_device() before.
 * @vdev: the vdpa device to be registered to vDPA bus
 * @nvqs: number of virtqueues supported by this device
 *
 * Return: Returns an error when fail to add to vDPA bus
 */
int vdpa_register_device(struct vdpa_device *vdev, int nvqs)
{
        int err;

        mutex_lock(&vdpa_dev_mutex);
        err = __vdpa_register_device(vdev, nvqs);
        mutex_unlock(&vdpa_dev_mutex);
        return err;
}
EXPORT_SYMBOL_GPL(vdpa_register_device);

/**
 * _vdpa_unregister_device - unregister a vDPA device
 * Caller must invoke this routine as part of management device dev_del()
 * callback.
 * @vdev: the vdpa device to be unregisted from vDPA bus
 */
void _vdpa_unregister_device(struct vdpa_device *vdev)
{
        lockdep_assert_held(&vdpa_dev_mutex);
        WARN_ON(!vdev->mdev);
        device_unregister(&vdev->dev);
}
EXPORT_SYMBOL_GPL(_vdpa_unregister_device);

/**
 * vdpa_unregister_device - unregister a vDPA device
 * @vdev: the vdpa device to be unregisted from vDPA bus
 */
void vdpa_unregister_device(struct vdpa_device *vdev)
{
        mutex_lock(&vdpa_dev_mutex);
        device_unregister(&vdev->dev);
        mutex_unlock(&vdpa_dev_mutex);
}
EXPORT_SYMBOL_GPL(vdpa_unregister_device);

/**
 * __vdpa_register_driver - register a vDPA device driver
 * @drv: the vdpa device driver to be registered
 * @owner: module owner of the driver
 *
 * Return: Returns an err when fail to do the registration
 */
int __vdpa_register_driver(struct vdpa_driver *drv, struct module *owner)
{
        drv->driver.bus = &vdpa_bus;
        drv->driver.owner = owner;

        return driver_register(&drv->driver);
}
EXPORT_SYMBOL_GPL(__vdpa_register_driver);

/**
 * vdpa_unregister_driver - unregister a vDPA device driver
 * @drv: the vdpa device driver to be unregistered
 */
void vdpa_unregister_driver(struct vdpa_driver *drv)
{
        driver_unregister(&drv->driver);
}
EXPORT_SYMBOL_GPL(vdpa_unregister_driver);

/**
 * vdpa_mgmtdev_register - register a vdpa management device
 *
 * @mdev: Pointer to vdpa management device
 * vdpa_mgmtdev_register() register a vdpa management device which supports
 * vdpa device management.
 * Return: Returns 0 on success or failure when required callback ops are not
 *         initialized.
 */
int vdpa_mgmtdev_register(struct vdpa_mgmt_dev *mdev)
{
        if (!mdev->device || !mdev->ops || !mdev->ops->dev_add || !mdev->ops->dev_del)
                return -EINVAL;

        INIT_LIST_HEAD(&mdev->list);
        mutex_lock(&vdpa_dev_mutex);
        list_add_tail(&mdev->list, &mdev_head);
        mutex_unlock(&vdpa_dev_mutex);
        return 0;
}
EXPORT_SYMBOL_GPL(vdpa_mgmtdev_register);

static int vdpa_match_remove(struct device *dev, void *data)
{
        struct vdpa_device *vdev = container_of(dev, struct vdpa_device, dev);
        struct vdpa_mgmt_dev *mdev = vdev->mdev;

        if (mdev == data)
                mdev->ops->dev_del(mdev, vdev);
        return 0;
}

void vdpa_mgmtdev_unregister(struct vdpa_mgmt_dev *mdev)
{
        mutex_lock(&vdpa_dev_mutex);

        list_del(&mdev->list);

        /* Filter out all the entries belong to this management device and delete it. */
        bus_for_each_dev(&vdpa_bus, NULL, mdev, vdpa_match_remove);

        mutex_unlock(&vdpa_dev_mutex);
}
EXPORT_SYMBOL_GPL(vdpa_mgmtdev_unregister);

static bool mgmtdev_handle_match(const struct vdpa_mgmt_dev *mdev,
                                 const char *busname, const char *devname)
{
        /* Bus name is optional for simulated management device, so ignore the
         * device with bus if bus attribute is provided.
         */
        if ((busname && !mdev->device->bus) || (!busname && mdev->device->bus))
                return false;

        if (!busname && strcmp(dev_name(mdev->device), devname) == 0)
                return true;

        if (busname && (strcmp(mdev->device->bus->name, busname) == 0) &&
            (strcmp(dev_name(mdev->device), devname) == 0))
                return true;

        return false;
}

static struct vdpa_mgmt_dev *vdpa_mgmtdev_get_from_attr(struct nlattr **attrs)
{
        struct vdpa_mgmt_dev *mdev;
        const char *busname = NULL;
        const char *devname;

        if (!attrs[VDPA_ATTR_MGMTDEV_DEV_NAME])
                return ERR_PTR(-EINVAL);
        devname = nla_data(attrs[VDPA_ATTR_MGMTDEV_DEV_NAME]);
        if (attrs[VDPA_ATTR_MGMTDEV_BUS_NAME])
                busname = nla_data(attrs[VDPA_ATTR_MGMTDEV_BUS_NAME]);

        list_for_each_entry(mdev, &mdev_head, list) {
                if (mgmtdev_handle_match(mdev, busname, devname))
                        return mdev;
        }
        return ERR_PTR(-ENODEV);
}

static int vdpa_nl_mgmtdev_handle_fill(struct sk_buff *msg, const struct vdpa_mgmt_dev *mdev)
{
        if (mdev->device->bus &&
            nla_put_string(msg, VDPA_ATTR_MGMTDEV_BUS_NAME, mdev->device->bus->name))
                return -EMSGSIZE;
        if (nla_put_string(msg, VDPA_ATTR_MGMTDEV_DEV_NAME, dev_name(mdev->device)))
                return -EMSGSIZE;
        return 0;
}

static int vdpa_mgmtdev_fill(const struct vdpa_mgmt_dev *mdev, struct sk_buff *msg,
                             u32 portid, u32 seq, int flags)
{
        u64 supported_classes = 0;
        void *hdr;
        int i = 0;
        int err;

        hdr = genlmsg_put(msg, portid, seq, &vdpa_nl_family, flags, VDPA_CMD_MGMTDEV_NEW);
        if (!hdr)
                return -EMSGSIZE;
        err = vdpa_nl_mgmtdev_handle_fill(msg, mdev);
        if (err)
                goto msg_err;

        while (mdev->id_table[i].device) {
                supported_classes |= BIT(mdev->id_table[i].device);
                i++;
        }

        if (nla_put_u64_64bit(msg, VDPA_ATTR_MGMTDEV_SUPPORTED_CLASSES,
                              supported_classes, VDPA_ATTR_UNSPEC)) {
                err = -EMSGSIZE;
                goto msg_err;
        }

        genlmsg_end(msg, hdr);
        return 0;

msg_err:
        genlmsg_cancel(msg, hdr);
        return err;
}

static int vdpa_nl_cmd_mgmtdev_get_doit(struct sk_buff *skb, struct genl_info *info)
{
        struct vdpa_mgmt_dev *mdev;
        struct sk_buff *msg;
        int err;

        msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
        if (!msg)
                return -ENOMEM;

        mutex_lock(&vdpa_dev_mutex);
        mdev = vdpa_mgmtdev_get_from_attr(info->attrs);
        if (IS_ERR(mdev)) {
                mutex_unlock(&vdpa_dev_mutex);
                NL_SET_ERR_MSG_MOD(info->extack, "Fail to find the specified mgmt device");
                err = PTR_ERR(mdev);
                goto out;
        }

        err = vdpa_mgmtdev_fill(mdev, msg, info->snd_portid, info->snd_seq, 0);
        mutex_unlock(&vdpa_dev_mutex);
        if (err)
                goto out;
        err = genlmsg_reply(msg, info);
        return err;

out:
        nlmsg_free(msg);
        return err;
}

static int
vdpa_nl_cmd_mgmtdev_get_dumpit(struct sk_buff *msg, struct netlink_callback *cb)
{
        struct vdpa_mgmt_dev *mdev;
        int start = cb->args[0];
        int idx = 0;
        int err;

        mutex_lock(&vdpa_dev_mutex);
        list_for_each_entry(mdev, &mdev_head, list) {
                if (idx < start) {
                        idx++;
                        continue;
                }
                err = vdpa_mgmtdev_fill(mdev, msg, NETLINK_CB(cb->skb).portid,
                                        cb->nlh->nlmsg_seq, NLM_F_MULTI);
                if (err)
                        goto out;
                idx++;
        }
out:
        mutex_unlock(&vdpa_dev_mutex);
        cb->args[0] = idx;
        return msg->len;
}

static int vdpa_nl_cmd_dev_add_set_doit(struct sk_buff *skb, struct genl_info *info)
{
        struct vdpa_mgmt_dev *mdev;
        const char *name;
        int err = 0;

        if (!info->attrs[VDPA_ATTR_DEV_NAME])
                return -EINVAL;

        name = nla_data(info->attrs[VDPA_ATTR_DEV_NAME]);

        mutex_lock(&vdpa_dev_mutex);
        mdev = vdpa_mgmtdev_get_from_attr(info->attrs);
        if (IS_ERR(mdev)) {
                NL_SET_ERR_MSG_MOD(info->extack, "Fail to find the specified management device");
                err = PTR_ERR(mdev);
                goto err;
        }

        err = mdev->ops->dev_add(mdev, name);
err:
        mutex_unlock(&vdpa_dev_mutex);
        return err;
}

static int vdpa_nl_cmd_dev_del_set_doit(struct sk_buff *skb, struct genl_info *info)
{
        struct vdpa_mgmt_dev *mdev;
        struct vdpa_device *vdev;
        struct device *dev;
        const char *name;
        int err = 0;

        if (!info->attrs[VDPA_ATTR_DEV_NAME])
                return -EINVAL;
        name = nla_data(info->attrs[VDPA_ATTR_DEV_NAME]);

        mutex_lock(&vdpa_dev_mutex);
        dev = bus_find_device(&vdpa_bus, NULL, name, vdpa_name_match);
        if (!dev) {
                NL_SET_ERR_MSG_MOD(info->extack, "device not found");
                err = -ENODEV;
                goto dev_err;
        }
        vdev = container_of(dev, struct vdpa_device, dev);
        if (!vdev->mdev) {
                NL_SET_ERR_MSG_MOD(info->extack, "Only user created device can be deleted by user");
                err = -EINVAL;
                goto mdev_err;
        }
        mdev = vdev->mdev;
        mdev->ops->dev_del(mdev, vdev);
mdev_err:
        put_device(dev);
dev_err:
        mutex_unlock(&vdpa_dev_mutex);
        return err;
}

static int
vdpa_dev_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq,
              int flags, struct netlink_ext_ack *extack)
{
        u16 max_vq_size;
        u32 device_id;
        u32 vendor_id;
        void *hdr;
        int err;

        hdr = genlmsg_put(msg, portid, seq, &vdpa_nl_family, flags, VDPA_CMD_DEV_NEW);
        if (!hdr)
                return -EMSGSIZE;

        err = vdpa_nl_mgmtdev_handle_fill(msg, vdev->mdev);
        if (err)
                goto msg_err;

        device_id = vdev->config->get_device_id(vdev);
        vendor_id = vdev->config->get_vendor_id(vdev);
        max_vq_size = vdev->config->get_vq_num_max(vdev);

        err = -EMSGSIZE;
        if (nla_put_string(msg, VDPA_ATTR_DEV_NAME, dev_name(&vdev->dev)))
                goto msg_err;
        if (nla_put_u32(msg, VDPA_ATTR_DEV_ID, device_id))
                goto msg_err;
        if (nla_put_u32(msg, VDPA_ATTR_DEV_VENDOR_ID, vendor_id))
                goto msg_err;
        if (nla_put_u32(msg, VDPA_ATTR_DEV_MAX_VQS, vdev->nvqs))
                goto msg_err;
        if (nla_put_u16(msg, VDPA_ATTR_DEV_MAX_VQ_SIZE, max_vq_size))
                goto msg_err;

        genlmsg_end(msg, hdr);
        return 0;

msg_err:
        genlmsg_cancel(msg, hdr);
        return err;
}

static int vdpa_nl_cmd_dev_get_doit(struct sk_buff *skb, struct genl_info *info)
{
        struct vdpa_device *vdev;
        struct sk_buff *msg;
        const char *devname;
        struct device *dev;
        int err;

        if (!info->attrs[VDPA_ATTR_DEV_NAME])
                return -EINVAL;
        devname = nla_data(info->attrs[VDPA_ATTR_DEV_NAME]);
        msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
        if (!msg)
                return -ENOMEM;

        mutex_lock(&vdpa_dev_mutex);
        dev = bus_find_device(&vdpa_bus, NULL, devname, vdpa_name_match);
        if (!dev) {
                NL_SET_ERR_MSG_MOD(info->extack, "device not found");
                err = -ENODEV;
                goto err;
        }
        vdev = container_of(dev, struct vdpa_device, dev);
        if (!vdev->mdev) {
                err = -EINVAL;
                goto mdev_err;
        }
        err = vdpa_dev_fill(vdev, msg, info->snd_portid, info->snd_seq, 0, info->extack);
        if (!err)
                err = genlmsg_reply(msg, info);
mdev_err:
        put_device(dev);
err:
        mutex_unlock(&vdpa_dev_mutex);
        if (err)
                nlmsg_free(msg);
        return err;
}

struct vdpa_dev_dump_info {
        struct sk_buff *msg;
        struct netlink_callback *cb;
        int start_idx;
        int idx;
};

static int vdpa_dev_dump(struct device *dev, void *data)
{
        struct vdpa_device *vdev = container_of(dev, struct vdpa_device, dev);
        struct vdpa_dev_dump_info *info = data;
        int err;

        if (!vdev->mdev)
                return 0;
        if (info->idx < info->start_idx) {
                info->idx++;
                return 0;
        }
        err = vdpa_dev_fill(vdev, info->msg, NETLINK_CB(info->cb->skb).portid,
                            info->cb->nlh->nlmsg_seq, NLM_F_MULTI, info->cb->extack);
        if (err)
                return err;

        info->idx++;
        return 0;
}

static int vdpa_nl_cmd_dev_get_dumpit(struct sk_buff *msg, struct netlink_callback *cb)
{
        struct vdpa_dev_dump_info info;

        info.msg = msg;
        info.cb = cb;
        info.start_idx = cb->args[0];
        info.idx = 0;

        mutex_lock(&vdpa_dev_mutex);
        bus_for_each_dev(&vdpa_bus, NULL, &info, vdpa_dev_dump);
        mutex_unlock(&vdpa_dev_mutex);
        cb->args[0] = info.idx;
        return msg->len;
}

static const struct nla_policy vdpa_nl_policy[VDPA_ATTR_MAX + 1] = {
        [VDPA_ATTR_MGMTDEV_BUS_NAME] = { .type = NLA_NUL_STRING },
        [VDPA_ATTR_MGMTDEV_DEV_NAME] = { .type = NLA_STRING },
        [VDPA_ATTR_DEV_NAME] = { .type = NLA_STRING },
};

static const struct genl_ops vdpa_nl_ops[] = {
        {
                .cmd = VDPA_CMD_MGMTDEV_GET,
                .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
                .doit = vdpa_nl_cmd_mgmtdev_get_doit,
                .dumpit = vdpa_nl_cmd_mgmtdev_get_dumpit,
        },
        {
                .cmd = VDPA_CMD_DEV_NEW,
                .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
                .doit = vdpa_nl_cmd_dev_add_set_doit,
                .flags = GENL_ADMIN_PERM,
        },
        {
                .cmd = VDPA_CMD_DEV_DEL,
                .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
                .doit = vdpa_nl_cmd_dev_del_set_doit,
                .flags = GENL_ADMIN_PERM,
        },
        {
                .cmd = VDPA_CMD_DEV_GET,
                .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
                .doit = vdpa_nl_cmd_dev_get_doit,
                .dumpit = vdpa_nl_cmd_dev_get_dumpit,
        },
};

static struct genl_family vdpa_nl_family __ro_after_init = {
        .name = VDPA_GENL_NAME,
        .version = VDPA_GENL_VERSION,
        .maxattr = VDPA_ATTR_MAX,
        .policy = vdpa_nl_policy,
        .netnsok = false,
        .module = THIS_MODULE,
        .ops = vdpa_nl_ops,
        .n_ops = ARRAY_SIZE(vdpa_nl_ops),
};

static int vdpa_init(void)
{
        int err;

        err = bus_register(&vdpa_bus);
        if (err)
                return err;
        err = genl_register_family(&vdpa_nl_family);
        if (err)
                goto err;
        return 0;

err:
        bus_unregister(&vdpa_bus);
        return err;
}

static void __exit vdpa_exit(void)
{
        genl_unregister_family(&vdpa_nl_family);
        bus_unregister(&vdpa_bus);
        ida_destroy(&vdpa_index_ida);
}
core_initcall(vdpa_init);
module_exit(vdpa_exit);

MODULE_AUTHOR("Jason Wang <jasowang@redhat.com>");
MODULE_LICENSE("GPL v2");