Merge tag 'regmap-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie...

[mirror_ubuntu-kernels.git] / drivers / iommu / iommu.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2007-2008 Advanced Micro Devices, Inc.
 * Author: Joerg Roedel <jroedel@suse.de>
 */

#define pr_fmt(fmt)    "iommu: " fmt

#include <linux/device.h>
#include <linux/dma-iommu.h>
#include <linux/kernel.h>
#include <linux/bits.h>
#include <linux/bug.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/iommu.h>
#include <linux/idr.h>
#include <linux/notifier.h>
#include <linux/err.h>
#include <linux/pci.h>
#include <linux/bitops.h>
#include <linux/property.h>
#include <linux/fsl/mc.h>
#include <linux/module.h>
#include <linux/cc_platform.h>
#include <trace/events/iommu.h>

static struct kset *iommu_group_kset;
static DEFINE_IDA(iommu_group_ida);

static unsigned int iommu_def_domain_type __read_mostly;
static bool iommu_dma_strict __read_mostly = IS_ENABLED(CONFIG_IOMMU_DEFAULT_DMA_STRICT);
static u32 iommu_cmd_line __read_mostly;

struct iommu_group {
        struct kobject kobj;
        struct kobject *devices_kobj;
        struct list_head devices;
        struct mutex mutex;
        struct blocking_notifier_head notifier;
        void *iommu_data;
        void (*iommu_data_release)(void *iommu_data);
        char *name;
        int id;
        struct iommu_domain *default_domain;
        struct iommu_domain *domain;
        struct list_head entry;
};

struct group_device {
        struct list_head list;
        struct device *dev;
        char *name;
};

struct iommu_group_attribute {
        struct attribute attr;
        ssize_t (*show)(struct iommu_group *group, char *buf);
        ssize_t (*store)(struct iommu_group *group,
                         const char *buf, size_t count);
};

static const char * const iommu_group_resv_type_string[] = {
        [IOMMU_RESV_DIRECT]                     = "direct",
        [IOMMU_RESV_DIRECT_RELAXABLE]           = "direct-relaxable",
        [IOMMU_RESV_RESERVED]                   = "reserved",
        [IOMMU_RESV_MSI]                        = "msi",
        [IOMMU_RESV_SW_MSI]                     = "msi",
};

#define IOMMU_CMD_LINE_DMA_API          BIT(0)
#define IOMMU_CMD_LINE_STRICT           BIT(1)

static int iommu_alloc_default_domain(struct iommu_group *group,
                                      struct device *dev);
static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
                                                 unsigned type);
static int __iommu_attach_device(struct iommu_domain *domain,
                                 struct device *dev);
static int __iommu_attach_group(struct iommu_domain *domain,
                                struct iommu_group *group);
static void __iommu_detach_group(struct iommu_domain *domain,
                                 struct iommu_group *group);
static int iommu_create_device_direct_mappings(struct iommu_group *group,
                                               struct device *dev);
static struct iommu_group *iommu_group_get_for_dev(struct device *dev);
static ssize_t iommu_group_store_type(struct iommu_group *group,
                                      const char *buf, size_t count);

#define IOMMU_GROUP_ATTR(_name, _mode, _show, _store)           \
struct iommu_group_attribute iommu_group_attr_##_name =         \
        __ATTR(_name, _mode, _show, _store)

#define to_iommu_group_attr(_attr)      \
        container_of(_attr, struct iommu_group_attribute, attr)
#define to_iommu_group(_kobj)           \
        container_of(_kobj, struct iommu_group, kobj)

static LIST_HEAD(iommu_device_list);
static DEFINE_SPINLOCK(iommu_device_lock);

/*
 * Use a function instead of an array here because the domain-type is a
 * bit-field, so an array would waste memory.
 */
static const char *iommu_domain_type_str(unsigned int t)
{
        switch (t) {
        case IOMMU_DOMAIN_BLOCKED:
                return "Blocked";
        case IOMMU_DOMAIN_IDENTITY:
                return "Passthrough";
        case IOMMU_DOMAIN_UNMANAGED:
                return "Unmanaged";
        case IOMMU_DOMAIN_DMA:
        case IOMMU_DOMAIN_DMA_FQ:
                return "Translated";
        default:
                return "Unknown";
        }
}

static int __init iommu_subsys_init(void)
{
        if (!(iommu_cmd_line & IOMMU_CMD_LINE_DMA_API)) {
                if (IS_ENABLED(CONFIG_IOMMU_DEFAULT_PASSTHROUGH))
                        iommu_set_default_passthrough(false);
                else
                        iommu_set_default_translated(false);

                if (iommu_default_passthrough() && cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
                        pr_info("Memory encryption detected - Disabling default IOMMU Passthrough\n");
                        iommu_set_default_translated(false);
                }
        }

        if (!iommu_default_passthrough() && !iommu_dma_strict)
                iommu_def_domain_type = IOMMU_DOMAIN_DMA_FQ;

        pr_info("Default domain type: %s %s\n",
                iommu_domain_type_str(iommu_def_domain_type),
                (iommu_cmd_line & IOMMU_CMD_LINE_DMA_API) ?
                        "(set via kernel command line)" : "");

        if (!iommu_default_passthrough())
                pr_info("DMA domain TLB invalidation policy: %s mode %s\n",
                        iommu_dma_strict ? "strict" : "lazy",
                        (iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
                                "(set via kernel command line)" : "");

        return 0;
}
subsys_initcall(iommu_subsys_init);

/**
 * iommu_device_register() - Register an IOMMU hardware instance
 * @iommu: IOMMU handle for the instance
 * @ops:   IOMMU ops to associate with the instance
 * @hwdev: (optional) actual instance device, used for fwnode lookup
 *
 * Return: 0 on success, or an error.
 */
int iommu_device_register(struct iommu_device *iommu,
                          const struct iommu_ops *ops, struct device *hwdev)
{
        /* We need to be able to take module references appropriately */
        if (WARN_ON(is_module_address((unsigned long)ops) && !ops->owner))
                return -EINVAL;

        iommu->ops = ops;
        if (hwdev)
                iommu->fwnode = hwdev->fwnode;

        spin_lock(&iommu_device_lock);
        list_add_tail(&iommu->list, &iommu_device_list);
        spin_unlock(&iommu_device_lock);
        return 0;
}
EXPORT_SYMBOL_GPL(iommu_device_register);

void iommu_device_unregister(struct iommu_device *iommu)
{
        spin_lock(&iommu_device_lock);
        list_del(&iommu->list);
        spin_unlock(&iommu_device_lock);
}
EXPORT_SYMBOL_GPL(iommu_device_unregister);

static struct dev_iommu *dev_iommu_get(struct device *dev)
{
        struct dev_iommu *param = dev->iommu;

        if (param)
                return param;

        param = kzalloc(sizeof(*param), GFP_KERNEL);
        if (!param)
                return NULL;

        mutex_init(&param->lock);
        dev->iommu = param;
        return param;
}

static void dev_iommu_free(struct device *dev)
{
        iommu_fwspec_free(dev);
        kfree(dev->iommu);
        dev->iommu = NULL;
}

static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
{
        const struct iommu_ops *ops = dev->bus->iommu_ops;
        struct iommu_device *iommu_dev;
        struct iommu_group *group;
        int ret;

        if (!ops)
                return -ENODEV;

        if (!dev_iommu_get(dev))
                return -ENOMEM;

        if (!try_module_get(ops->owner)) {
                ret = -EINVAL;
                goto err_free;
        }

        iommu_dev = ops->probe_device(dev);
        if (IS_ERR(iommu_dev)) {
                ret = PTR_ERR(iommu_dev);
                goto out_module_put;
        }

        dev->iommu->iommu_dev = iommu_dev;

        group = iommu_group_get_for_dev(dev);
        if (IS_ERR(group)) {
                ret = PTR_ERR(group);
                goto out_release;
        }
        iommu_group_put(group);

        if (group_list && !group->default_domain && list_empty(&group->entry))
                list_add_tail(&group->entry, group_list);

        iommu_device_link(iommu_dev, dev);

        return 0;

out_release:
        ops->release_device(dev);

out_module_put:
        module_put(ops->owner);

err_free:
        dev_iommu_free(dev);

        return ret;
}

int iommu_probe_device(struct device *dev)
{
        const struct iommu_ops *ops = dev->bus->iommu_ops;
        struct iommu_group *group;
        int ret;

        ret = __iommu_probe_device(dev, NULL);
        if (ret)
                goto err_out;

        group = iommu_group_get(dev);
        if (!group) {
                ret = -ENODEV;
                goto err_release;
        }

        /*
         * Try to allocate a default domain - needs support from the
         * IOMMU driver. There are still some drivers which don't
         * support default domains, so the return value is not yet
         * checked.
         */
        mutex_lock(&group->mutex);
        iommu_alloc_default_domain(group, dev);
        mutex_unlock(&group->mutex);

        if (group->default_domain) {
                ret = __iommu_attach_device(group->default_domain, dev);
                if (ret) {
                        iommu_group_put(group);
                        goto err_release;
                }
        }

        iommu_create_device_direct_mappings(group, dev);

        iommu_group_put(group);

        if (ops->probe_finalize)
                ops->probe_finalize(dev);

        return 0;

err_release:
        iommu_release_device(dev);

err_out:
        return ret;

}

void iommu_release_device(struct device *dev)
{
        const struct iommu_ops *ops = dev->bus->iommu_ops;

        if (!dev->iommu)
                return;

        iommu_device_unlink(dev->iommu->iommu_dev, dev);

        ops->release_device(dev);

        iommu_group_remove_device(dev);
        module_put(ops->owner);
        dev_iommu_free(dev);
}

static int __init iommu_set_def_domain_type(char *str)
{
        bool pt;
        int ret;

        ret = kstrtobool(str, &pt);
        if (ret)
                return ret;

        if (pt)
                iommu_set_default_passthrough(true);
        else
                iommu_set_default_translated(true);

        return 0;
}
early_param("iommu.passthrough", iommu_set_def_domain_type);

static int __init iommu_dma_setup(char *str)
{
        int ret = kstrtobool(str, &iommu_dma_strict);

        if (!ret)
                iommu_cmd_line |= IOMMU_CMD_LINE_STRICT;
        return ret;
}
early_param("iommu.strict", iommu_dma_setup);

void iommu_set_dma_strict(void)
{
        iommu_dma_strict = true;
        if (iommu_def_domain_type == IOMMU_DOMAIN_DMA_FQ)
                iommu_def_domain_type = IOMMU_DOMAIN_DMA;
}

static ssize_t iommu_group_attr_show(struct kobject *kobj,
                                     struct attribute *__attr, char *buf)
{
        struct iommu_group_attribute *attr = to_iommu_group_attr(__attr);
        struct iommu_group *group = to_iommu_group(kobj);
        ssize_t ret = -EIO;

        if (attr->show)
                ret = attr->show(group, buf);
        return ret;
}

static ssize_t iommu_group_attr_store(struct kobject *kobj,
                                      struct attribute *__attr,
                                      const char *buf, size_t count)
{
        struct iommu_group_attribute *attr = to_iommu_group_attr(__attr);
        struct iommu_group *group = to_iommu_group(kobj);
        ssize_t ret = -EIO;

        if (attr->store)
                ret = attr->store(group, buf, count);
        return ret;
}

static const struct sysfs_ops iommu_group_sysfs_ops = {
        .show = iommu_group_attr_show,
        .store = iommu_group_attr_store,
};

static int iommu_group_create_file(struct iommu_group *group,
                                   struct iommu_group_attribute *attr)
{
        return sysfs_create_file(&group->kobj, &attr->attr);
}

static void iommu_group_remove_file(struct iommu_group *group,
                                    struct iommu_group_attribute *attr)
{
        sysfs_remove_file(&group->kobj, &attr->attr);
}

static ssize_t iommu_group_show_name(struct iommu_group *group, char *buf)
{
        return sprintf(buf, "%s\n", group->name);
}

/**
 * iommu_insert_resv_region - Insert a new region in the
 * list of reserved regions.
 * @new: new region to insert
 * @regions: list of regions
 *
 * Elements are sorted by start address and overlapping segments
 * of the same type are merged.
 */
static int iommu_insert_resv_region(struct iommu_resv_region *new,
                                    struct list_head *regions)
{
        struct iommu_resv_region *iter, *tmp, *nr, *top;
        LIST_HEAD(stack);

        nr = iommu_alloc_resv_region(new->start, new->length,
                                     new->prot, new->type);
        if (!nr)
                return -ENOMEM;

        /* First add the new element based on start address sorting */
        list_for_each_entry(iter, regions, list) {
                if (nr->start < iter->start ||
                    (nr->start == iter->start && nr->type <= iter->type))
                        break;
        }
        list_add_tail(&nr->list, &iter->list);

        /* Merge overlapping segments of type nr->type in @regions, if any */
        list_for_each_entry_safe(iter, tmp, regions, list) {
                phys_addr_t top_end, iter_end = iter->start + iter->length - 1;

                /* no merge needed on elements of different types than @new */
                if (iter->type != new->type) {
                        list_move_tail(&iter->list, &stack);
                        continue;
                }

                /* look for the last stack element of same type as @iter */
                list_for_each_entry_reverse(top, &stack, list)
                        if (top->type == iter->type)
                                goto check_overlap;

                list_move_tail(&iter->list, &stack);
                continue;

check_overlap:
                top_end = top->start + top->length - 1;

                if (iter->start > top_end + 1) {
                        list_move_tail(&iter->list, &stack);
                } else {
                        top->length = max(top_end, iter_end) - top->start + 1;
                        list_del(&iter->list);
                        kfree(iter);
                }
        }
        list_splice(&stack, regions);
        return 0;
}

static int
iommu_insert_device_resv_regions(struct list_head *dev_resv_regions,
                                 struct list_head *group_resv_regions)
{
        struct iommu_resv_region *entry;
        int ret = 0;

        list_for_each_entry(entry, dev_resv_regions, list) {
                ret = iommu_insert_resv_region(entry, group_resv_regions);
                if (ret)
                        break;
        }
        return ret;
}

int iommu_get_group_resv_regions(struct iommu_group *group,
                                 struct list_head *head)
{
        struct group_device *device;
        int ret = 0;

        mutex_lock(&group->mutex);
        list_for_each_entry(device, &group->devices, list) {
                struct list_head dev_resv_regions;

                INIT_LIST_HEAD(&dev_resv_regions);
                iommu_get_resv_regions(device->dev, &dev_resv_regions);
                ret = iommu_insert_device_resv_regions(&dev_resv_regions, head);
                iommu_put_resv_regions(device->dev, &dev_resv_regions);
                if (ret)
                        break;
        }
        mutex_unlock(&group->mutex);
        return ret;
}
EXPORT_SYMBOL_GPL(iommu_get_group_resv_regions);

static ssize_t iommu_group_show_resv_regions(struct iommu_group *group,
                                             char *buf)
{
        struct iommu_resv_region *region, *next;
        struct list_head group_resv_regions;
        char *str = buf;

        INIT_LIST_HEAD(&group_resv_regions);
        iommu_get_group_resv_regions(group, &group_resv_regions);

        list_for_each_entry_safe(region, next, &group_resv_regions, list) {
                str += sprintf(str, "0x%016llx 0x%016llx %s\n",
                               (long long int)region->start,
                               (long long int)(region->start +
                                                region->length - 1),
                               iommu_group_resv_type_string[region->type]);
                kfree(region);
        }

        return (str - buf);
}

static ssize_t iommu_group_show_type(struct iommu_group *group,
                                     char *buf)
{
        char *type = "unknown\n";

        mutex_lock(&group->mutex);
        if (group->default_domain) {
                switch (group->default_domain->type) {
                case IOMMU_DOMAIN_BLOCKED:
                        type = "blocked\n";
                        break;
                case IOMMU_DOMAIN_IDENTITY:
                        type = "identity\n";
                        break;
                case IOMMU_DOMAIN_UNMANAGED:
                        type = "unmanaged\n";
                        break;
                case IOMMU_DOMAIN_DMA:
                        type = "DMA\n";
                        break;
                case IOMMU_DOMAIN_DMA_FQ:
                        type = "DMA-FQ\n";
                        break;
                }
        }
        mutex_unlock(&group->mutex);
        strcpy(buf, type);

        return strlen(type);
}

static IOMMU_GROUP_ATTR(name, S_IRUGO, iommu_group_show_name, NULL);

static IOMMU_GROUP_ATTR(reserved_regions, 0444,
                        iommu_group_show_resv_regions, NULL);

static IOMMU_GROUP_ATTR(type, 0644, iommu_group_show_type,
                        iommu_group_store_type);

static void iommu_group_release(struct kobject *kobj)
{
        struct iommu_group *group = to_iommu_group(kobj);

        pr_debug("Releasing group %d\n", group->id);

        if (group->iommu_data_release)
                group->iommu_data_release(group->iommu_data);

        ida_simple_remove(&iommu_group_ida, group->id);

        if (group->default_domain)
                iommu_domain_free(group->default_domain);

        kfree(group->name);
        kfree(group);
}

static struct kobj_type iommu_group_ktype = {
        .sysfs_ops = &iommu_group_sysfs_ops,
        .release = iommu_group_release,
};

/**
 * iommu_group_alloc - Allocate a new group
 *
 * This function is called by an iommu driver to allocate a new iommu
 * group.  The iommu group represents the minimum granularity of the iommu.
 * Upon successful return, the caller holds a reference to the supplied
 * group in order to hold the group until devices are added.  Use
 * iommu_group_put() to release this extra reference count, allowing the
 * group to be automatically reclaimed once it has no devices or external
 * references.
 */
struct iommu_group *iommu_group_alloc(void)
{
        struct iommu_group *group;
        int ret;

        group = kzalloc(sizeof(*group), GFP_KERNEL);
        if (!group)
                return ERR_PTR(-ENOMEM);

        group->kobj.kset = iommu_group_kset;
        mutex_init(&group->mutex);
        INIT_LIST_HEAD(&group->devices);
        INIT_LIST_HEAD(&group->entry);
        BLOCKING_INIT_NOTIFIER_HEAD(&group->notifier);

        ret = ida_simple_get(&iommu_group_ida, 0, 0, GFP_KERNEL);
        if (ret < 0) {
                kfree(group);
                return ERR_PTR(ret);
        }
        group->id = ret;

        ret = kobject_init_and_add(&group->kobj, &iommu_group_ktype,
                                   NULL, "%d", group->id);
        if (ret) {
                ida_simple_remove(&iommu_group_ida, group->id);
                kobject_put(&group->kobj);
                return ERR_PTR(ret);
        }

        group->devices_kobj = kobject_create_and_add("devices", &group->kobj);
        if (!group->devices_kobj) {
                kobject_put(&group->kobj); /* triggers .release & free */
                return ERR_PTR(-ENOMEM);
        }

        /*
         * The devices_kobj holds a reference on the group kobject, so
         * as long as that exists so will the group.  We can therefore
         * use the devices_kobj for reference counting.
         */
        kobject_put(&group->kobj);

        ret = iommu_group_create_file(group,
                                      &iommu_group_attr_reserved_regions);
        if (ret)
                return ERR_PTR(ret);

        ret = iommu_group_create_file(group, &iommu_group_attr_type);
        if (ret)
                return ERR_PTR(ret);

        pr_debug("Allocated group %d\n", group->id);

        return group;
}
EXPORT_SYMBOL_GPL(iommu_group_alloc);

struct iommu_group *iommu_group_get_by_id(int id)
{
        struct kobject *group_kobj;
        struct iommu_group *group;
        const char *name;

        if (!iommu_group_kset)
                return NULL;

        name = kasprintf(GFP_KERNEL, "%d", id);
        if (!name)
                return NULL;

        group_kobj = kset_find_obj(iommu_group_kset, name);
        kfree(name);

        if (!group_kobj)
                return NULL;

        group = container_of(group_kobj, struct iommu_group, kobj);
        BUG_ON(group->id != id);

        kobject_get(group->devices_kobj);
        kobject_put(&group->kobj);

        return group;
}
EXPORT_SYMBOL_GPL(iommu_group_get_by_id);

/**
 * iommu_group_get_iommudata - retrieve iommu_data registered for a group
 * @group: the group
 *
 * iommu drivers can store data in the group for use when doing iommu
 * operations.  This function provides a way to retrieve it.  Caller
 * should hold a group reference.
 */
void *iommu_group_get_iommudata(struct iommu_group *group)
{
        return group->iommu_data;
}
EXPORT_SYMBOL_GPL(iommu_group_get_iommudata);

/**
 * iommu_group_set_iommudata - set iommu_data for a group
 * @group: the group
 * @iommu_data: new data
 * @release: release function for iommu_data
 *
 * iommu drivers can store data in the group for use when doing iommu
 * operations.  This function provides a way to set the data after
 * the group has been allocated.  Caller should hold a group reference.
 */
void iommu_group_set_iommudata(struct iommu_group *group, void *iommu_data,
                               void (*release)(void *iommu_data))
{
        group->iommu_data = iommu_data;
        group->iommu_data_release = release;
}
EXPORT_SYMBOL_GPL(iommu_group_set_iommudata);

/**
 * iommu_group_set_name - set name for a group
 * @group: the group
 * @name: name
 *
 * Allow iommu driver to set a name for a group.  When set it will
 * appear in a name attribute file under the group in sysfs.
 */
int iommu_group_set_name(struct iommu_group *group, const char *name)
{
        int ret;

        if (group->name) {
                iommu_group_remove_file(group, &iommu_group_attr_name);
                kfree(group->name);
                group->name = NULL;
                if (!name)
                        return 0;
        }

        group->name = kstrdup(name, GFP_KERNEL);
        if (!group->name)
                return -ENOMEM;

        ret = iommu_group_create_file(group, &iommu_group_attr_name);
        if (ret) {
                kfree(group->name);
                group->name = NULL;
                return ret;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(iommu_group_set_name);

static int iommu_create_device_direct_mappings(struct iommu_group *group,
                                               struct device *dev)
{
        struct iommu_domain *domain = group->default_domain;
        struct iommu_resv_region *entry;
        struct list_head mappings;
        unsigned long pg_size;
        int ret = 0;

        if (!domain || !iommu_is_dma_domain(domain))
                return 0;

        BUG_ON(!domain->pgsize_bitmap);

        pg_size = 1UL << __ffs(domain->pgsize_bitmap);
        INIT_LIST_HEAD(&mappings);

        iommu_get_resv_regions(dev, &mappings);

        /* We need to consider overlapping regions for different devices */
        list_for_each_entry(entry, &mappings, list) {
                dma_addr_t start, end, addr;
                size_t map_size = 0;

                if (domain->ops->apply_resv_region)
                        domain->ops->apply_resv_region(dev, domain, entry);

                start = ALIGN(entry->start, pg_size);
                end   = ALIGN(entry->start + entry->length, pg_size);

                if (entry->type != IOMMU_RESV_DIRECT &&
                    entry->type != IOMMU_RESV_DIRECT_RELAXABLE)
                        continue;

                for (addr = start; addr <= end; addr += pg_size) {
                        phys_addr_t phys_addr;

                        if (addr == end)
                                goto map_end;

                        phys_addr = iommu_iova_to_phys(domain, addr);
                        if (!phys_addr) {
                                map_size += pg_size;
                                continue;
                        }

map_end:
                        if (map_size) {
                                ret = iommu_map(domain, addr - map_size,
                                                addr - map_size, map_size,
                                                entry->prot);
                                if (ret)
                                        goto out;
                                map_size = 0;
                        }
                }

        }

        iommu_flush_iotlb_all(domain);

out:
        iommu_put_resv_regions(dev, &mappings);

        return ret;
}

static bool iommu_is_attach_deferred(struct iommu_domain *domain,
                                     struct device *dev)
{
        if (domain->ops->is_attach_deferred)
                return domain->ops->is_attach_deferred(domain, dev);

        return false;
}

/**
 * iommu_group_add_device - add a device to an iommu group
 * @group: the group into which to add the device (reference should be held)
 * @dev: the device
 *
 * This function is called by an iommu driver to add a device into a
 * group.  Adding a device increments the group reference count.
 */
int iommu_group_add_device(struct iommu_group *group, struct device *dev)
{
        int ret, i = 0;
        struct group_device *device;

        device = kzalloc(sizeof(*device), GFP_KERNEL);
        if (!device)
                return -ENOMEM;

        device->dev = dev;

        ret = sysfs_create_link(&dev->kobj, &group->kobj, "iommu_group");
        if (ret)
                goto err_free_device;

        device->name = kasprintf(GFP_KERNEL, "%s", kobject_name(&dev->kobj));
rename:
        if (!device->name) {
                ret = -ENOMEM;
                goto err_remove_link;
        }

        ret = sysfs_create_link_nowarn(group->devices_kobj,
                                       &dev->kobj, device->name);
        if (ret) {
                if (ret == -EEXIST && i >= 0) {
                        /*
                         * Account for the slim chance of collision
                         * and append an instance to the name.
                         */
                        kfree(device->name);
                        device->name = kasprintf(GFP_KERNEL, "%s.%d",
                                                 kobject_name(&dev->kobj), i++);
                        goto rename;
                }
                goto err_free_name;
        }

        kobject_get(group->devices_kobj);

        dev->iommu_group = group;

        mutex_lock(&group->mutex);
        list_add_tail(&device->list, &group->devices);
        if (group->domain  && !iommu_is_attach_deferred(group->domain, dev))
                ret = __iommu_attach_device(group->domain, dev);
        mutex_unlock(&group->mutex);
        if (ret)
                goto err_put_group;

        /* Notify any listeners about change to group. */
        blocking_notifier_call_chain(&group->notifier,
                                     IOMMU_GROUP_NOTIFY_ADD_DEVICE, dev);

        trace_add_device_to_group(group->id, dev);

        dev_info(dev, "Adding to iommu group %d\n", group->id);

        return 0;

err_put_group:
        mutex_lock(&group->mutex);
        list_del(&device->list);
        mutex_unlock(&group->mutex);
        dev->iommu_group = NULL;
        kobject_put(group->devices_kobj);
        sysfs_remove_link(group->devices_kobj, device->name);
err_free_name:
        kfree(device->name);
err_remove_link:
        sysfs_remove_link(&dev->kobj, "iommu_group");
err_free_device:
        kfree(device);
        dev_err(dev, "Failed to add to iommu group %d: %d\n", group->id, ret);
        return ret;
}
EXPORT_SYMBOL_GPL(iommu_group_add_device);

/**
 * iommu_group_remove_device - remove a device from it's current group
 * @dev: device to be removed
 *
 * This function is called by an iommu driver to remove the device from
 * it's current group.  This decrements the iommu group reference count.
 */
void iommu_group_remove_device(struct device *dev)
{
        struct iommu_group *group = dev->iommu_group;
        struct group_device *tmp_device, *device = NULL;

        if (!group)
                return;

        dev_info(dev, "Removing from iommu group %d\n", group->id);

        /* Pre-notify listeners that a device is being removed. */
        blocking_notifier_call_chain(&group->notifier,
                                     IOMMU_GROUP_NOTIFY_DEL_DEVICE, dev);

        mutex_lock(&group->mutex);
        list_for_each_entry(tmp_device, &group->devices, list) {
                if (tmp_device->dev == dev) {
                        device = tmp_device;
                        list_del(&device->list);
                        break;
                }
        }
        mutex_unlock(&group->mutex);

        if (!device)
                return;

        sysfs_remove_link(group->devices_kobj, device->name);
        sysfs_remove_link(&dev->kobj, "iommu_group");

        trace_remove_device_from_group(group->id, dev);

        kfree(device->name);
        kfree(device);
        dev->iommu_group = NULL;
        kobject_put(group->devices_kobj);
}
EXPORT_SYMBOL_GPL(iommu_group_remove_device);

static int iommu_group_device_count(struct iommu_group *group)
{
        struct group_device *entry;
        int ret = 0;

        list_for_each_entry(entry, &group->devices, list)
                ret++;

        return ret;
}

/**
 * iommu_group_for_each_dev - iterate over each device in the group
 * @group: the group
 * @data: caller opaque data to be passed to callback function
 * @fn: caller supplied callback function
 *
 * This function is called by group users to iterate over group devices.
 * Callers should hold a reference count to the group during callback.
 * The group->mutex is held across callbacks, which will block calls to
 * iommu_group_add/remove_device.
 */
static int __iommu_group_for_each_dev(struct iommu_group *group, void *data,
                                      int (*fn)(struct device *, void *))
{
        struct group_device *device;
        int ret = 0;

        list_for_each_entry(device, &group->devices, list) {
                ret = fn(device->dev, data);
                if (ret)
                        break;
        }
        return ret;
}


int iommu_group_for_each_dev(struct iommu_group *group, void *data,
                             int (*fn)(struct device *, void *))
{
        int ret;

        mutex_lock(&group->mutex);
        ret = __iommu_group_for_each_dev(group, data, fn);
        mutex_unlock(&group->mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_group_for_each_dev);

/**
 * iommu_group_get - Return the group for a device and increment reference
 * @dev: get the group that this device belongs to
 *
 * This function is called by iommu drivers and users to get the group
 * for the specified device.  If found, the group is returned and the group
 * reference in incremented, else NULL.
 */
struct iommu_group *iommu_group_get(struct device *dev)
{
        struct iommu_group *group = dev->iommu_group;

        if (group)
                kobject_get(group->devices_kobj);

        return group;
}
EXPORT_SYMBOL_GPL(iommu_group_get);

/**
 * iommu_group_ref_get - Increment reference on a group
 * @group: the group to use, must not be NULL
 *
 * This function is called by iommu drivers to take additional references on an
 * existing group.  Returns the given group for convenience.
 */
struct iommu_group *iommu_group_ref_get(struct iommu_group *group)
{
        kobject_get(group->devices_kobj);
        return group;
}
EXPORT_SYMBOL_GPL(iommu_group_ref_get);

/**
 * iommu_group_put - Decrement group reference
 * @group: the group to use
 *
 * This function is called by iommu drivers and users to release the
 * iommu group.  Once the reference count is zero, the group is released.
 */
void iommu_group_put(struct iommu_group *group)
{
        if (group)
                kobject_put(group->devices_kobj);
}
EXPORT_SYMBOL_GPL(iommu_group_put);

/**
 * iommu_group_register_notifier - Register a notifier for group changes
 * @group: the group to watch
 * @nb: notifier block to signal
 *
 * This function allows iommu group users to track changes in a group.
 * See include/linux/iommu.h for actions sent via this notifier.  Caller
 * should hold a reference to the group throughout notifier registration.
 */
int iommu_group_register_notifier(struct iommu_group *group,
                                  struct notifier_block *nb)
{
        return blocking_notifier_chain_register(&group->notifier, nb);
}
EXPORT_SYMBOL_GPL(iommu_group_register_notifier);

/**
 * iommu_group_unregister_notifier - Unregister a notifier
 * @group: the group to watch
 * @nb: notifier block to signal
 *
 * Unregister a previously registered group notifier block.
 */
int iommu_group_unregister_notifier(struct iommu_group *group,
                                    struct notifier_block *nb)
{
        return blocking_notifier_chain_unregister(&group->notifier, nb);
}
EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier);

/**
 * iommu_register_device_fault_handler() - Register a device fault handler
 * @dev: the device
 * @handler: the fault handler
 * @data: private data passed as argument to the handler
 *
 * When an IOMMU fault event is received, this handler gets called with the
 * fault event and data as argument. The handler should return 0 on success. If
 * the fault is recoverable (IOMMU_FAULT_PAGE_REQ), the consumer should also
 * complete the fault by calling iommu_page_response() with one of the following
 * response code:
 * - IOMMU_PAGE_RESP_SUCCESS: retry the translation
 * - IOMMU_PAGE_RESP_INVALID: terminate the fault
 * - IOMMU_PAGE_RESP_FAILURE: terminate the fault and stop reporting
 *   page faults if possible.
 *
 * Return 0 if the fault handler was installed successfully, or an error.
 */
int iommu_register_device_fault_handler(struct device *dev,
                                        iommu_dev_fault_handler_t handler,
                                        void *data)
{
        struct dev_iommu *param = dev->iommu;
        int ret = 0;

        if (!param)
                return -EINVAL;

        mutex_lock(&param->lock);
        /* Only allow one fault handler registered for each device */
        if (param->fault_param) {
                ret = -EBUSY;
                goto done_unlock;
        }

        get_device(dev);
        param->fault_param = kzalloc(sizeof(*param->fault_param), GFP_KERNEL);
        if (!param->fault_param) {
                put_device(dev);
                ret = -ENOMEM;
                goto done_unlock;
        }
        param->fault_param->handler = handler;
        param->fault_param->data = data;
        mutex_init(&param->fault_param->lock);
        INIT_LIST_HEAD(&param->fault_param->faults);

done_unlock:
        mutex_unlock(&param->lock);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_register_device_fault_handler);

/**
 * iommu_unregister_device_fault_handler() - Unregister the device fault handler
 * @dev: the device
 *
 * Remove the device fault handler installed with
 * iommu_register_device_fault_handler().
 *
 * Return 0 on success, or an error.
 */
int iommu_unregister_device_fault_handler(struct device *dev)
{
        struct dev_iommu *param = dev->iommu;
        int ret = 0;

        if (!param)
                return -EINVAL;

        mutex_lock(&param->lock);

        if (!param->fault_param)
                goto unlock;

        /* we cannot unregister handler if there are pending faults */
        if (!list_empty(&param->fault_param->faults)) {
                ret = -EBUSY;
                goto unlock;
        }

        kfree(param->fault_param);
        param->fault_param = NULL;
        put_device(dev);
unlock:
        mutex_unlock(&param->lock);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_unregister_device_fault_handler);

/**
 * iommu_report_device_fault() - Report fault event to device driver
 * @dev: the device
 * @evt: fault event data
 *
 * Called by IOMMU drivers when a fault is detected, typically in a threaded IRQ
 * handler. When this function fails and the fault is recoverable, it is the
 * caller's responsibility to complete the fault.
 *
 * Return 0 on success, or an error.
 */
int iommu_report_device_fault(struct device *dev, struct iommu_fault_event *evt)
{
        struct dev_iommu *param = dev->iommu;
        struct iommu_fault_event *evt_pending = NULL;
        struct iommu_fault_param *fparam;
        int ret = 0;

        if (!param || !evt)
                return -EINVAL;

        /* we only report device fault if there is a handler registered */
        mutex_lock(&param->lock);
        fparam = param->fault_param;
        if (!fparam || !fparam->handler) {
                ret = -EINVAL;
                goto done_unlock;
        }

        if (evt->fault.type == IOMMU_FAULT_PAGE_REQ &&
            (evt->fault.prm.flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE)) {
                evt_pending = kmemdup(evt, sizeof(struct iommu_fault_event),
                                      GFP_KERNEL);
                if (!evt_pending) {
                        ret = -ENOMEM;
                        goto done_unlock;
                }
                mutex_lock(&fparam->lock);
                list_add_tail(&evt_pending->list, &fparam->faults);
                mutex_unlock(&fparam->lock);
        }

        ret = fparam->handler(&evt->fault, fparam->data);
        if (ret && evt_pending) {
                mutex_lock(&fparam->lock);
                list_del(&evt_pending->list);
                mutex_unlock(&fparam->lock);
                kfree(evt_pending);
        }
done_unlock:
        mutex_unlock(&param->lock);
        return ret;
}
EXPORT_SYMBOL_GPL(iommu_report_device_fault);

int iommu_page_response(struct device *dev,
                        struct iommu_page_response *msg)
{
        bool needs_pasid;
        int ret = -EINVAL;
        struct iommu_fault_event *evt;
        struct iommu_fault_page_request *prm;
        struct dev_iommu *param = dev->iommu;
        bool has_pasid = msg->flags & IOMMU_PAGE_RESP_PASID_VALID;
        struct iommu_domain *domain = iommu_get_domain_for_dev(dev);

        if (!domain || !domain->ops->page_response)
                return -ENODEV;

        if (!param || !param->fault_param)
                return -EINVAL;

        if (msg->version != IOMMU_PAGE_RESP_VERSION_1 ||
            msg->flags & ~IOMMU_PAGE_RESP_PASID_VALID)
                return -EINVAL;

        /* Only send response if there is a fault report pending */
        mutex_lock(&param->fault_param->lock);
        if (list_empty(&param->fault_param->faults)) {
                dev_warn_ratelimited(dev, "no pending PRQ, drop response\n");
                goto done_unlock;
        }
        /*
         * Check if we have a matching page request pending to respond,
         * otherwise return -EINVAL
         */
        list_for_each_entry(evt, &param->fault_param->faults, list) {
                prm = &evt->fault.prm;
                if (prm->grpid != msg->grpid)
                        continue;

                /*
                 * If the PASID is required, the corresponding request is
                 * matched using the group ID, the PASID valid bit and the PASID
                 * value. Otherwise only the group ID matches request and
                 * response.
                 */
                needs_pasid = prm->flags & IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID;
                if (needs_pasid && (!has_pasid || msg->pasid != prm->pasid))
                        continue;

                if (!needs_pasid && has_pasid) {
                        /* No big deal, just clear it. */
                        msg->flags &= ~IOMMU_PAGE_RESP_PASID_VALID;
                        msg->pasid = 0;
                }

                ret = domain->ops->page_response(dev, evt, msg);
                list_del(&evt->list);
                kfree(evt);
                break;
        }

done_unlock:
        mutex_unlock(&param->fault_param->lock);
        return ret;
}
EXPORT_SYMBOL_GPL(iommu_page_response);

/**
 * iommu_group_id - Return ID for a group
 * @group: the group to ID
 *
 * Return the unique ID for the group matching the sysfs group number.
 */
int iommu_group_id(struct iommu_group *group)
{
        return group->id;
}
EXPORT_SYMBOL_GPL(iommu_group_id);

static struct iommu_group *get_pci_alias_group(struct pci_dev *pdev,
                                               unsigned long *devfns);

/*
 * To consider a PCI device isolated, we require ACS to support Source
 * Validation, Request Redirection, Completer Redirection, and Upstream
 * Forwarding.  This effectively means that devices cannot spoof their
 * requester ID, requests and completions cannot be redirected, and all
 * transactions are forwarded upstream, even as it passes through a
 * bridge where the target device is downstream.
 */
#define REQ_ACS_FLAGS   (PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF)

/*
 * For multifunction devices which are not isolated from each other, find
 * all the other non-isolated functions and look for existing groups.  For
 * each function, we also need to look for aliases to or from other devices
 * that may already have a group.
 */
static struct iommu_group *get_pci_function_alias_group(struct pci_dev *pdev,
                                                        unsigned long *devfns)
{
        struct pci_dev *tmp = NULL;
        struct iommu_group *group;

        if (!pdev->multifunction || pci_acs_enabled(pdev, REQ_ACS_FLAGS))
                return NULL;

        for_each_pci_dev(tmp) {
                if (tmp == pdev || tmp->bus != pdev->bus ||
                    PCI_SLOT(tmp->devfn) != PCI_SLOT(pdev->devfn) ||
                    pci_acs_enabled(tmp, REQ_ACS_FLAGS))
                        continue;

                group = get_pci_alias_group(tmp, devfns);
                if (group) {
                        pci_dev_put(tmp);
                        return group;
                }
        }

        return NULL;
}

/*
 * Look for aliases to or from the given device for existing groups. DMA
 * aliases are only supported on the same bus, therefore the search
 * space is quite small (especially since we're really only looking at pcie
 * device, and therefore only expect multiple slots on the root complex or
 * downstream switch ports).  It's conceivable though that a pair of
 * multifunction devices could have aliases between them that would cause a
 * loop.  To prevent this, we use a bitmap to track where we've been.
 */
static struct iommu_group *get_pci_alias_group(struct pci_dev *pdev,
                                               unsigned long *devfns)
{
        struct pci_dev *tmp = NULL;
        struct iommu_group *group;

        if (test_and_set_bit(pdev->devfn & 0xff, devfns))
                return NULL;

        group = iommu_group_get(&pdev->dev);
        if (group)
                return group;

        for_each_pci_dev(tmp) {
                if (tmp == pdev || tmp->bus != pdev->bus)
                        continue;

                /* We alias them or they alias us */
                if (pci_devs_are_dma_aliases(pdev, tmp)) {
                        group = get_pci_alias_group(tmp, devfns);
                        if (group) {
                                pci_dev_put(tmp);
                                return group;
                        }

                        group = get_pci_function_alias_group(tmp, devfns);
                        if (group) {
                                pci_dev_put(tmp);
                                return group;
                        }
                }
        }

        return NULL;
}

struct group_for_pci_data {
        struct pci_dev *pdev;
        struct iommu_group *group;
};

/*
 * DMA alias iterator callback, return the last seen device.  Stop and return
 * the IOMMU group if we find one along the way.
 */
static int get_pci_alias_or_group(struct pci_dev *pdev, u16 alias, void *opaque)
{
        struct group_for_pci_data *data = opaque;

        data->pdev = pdev;
        data->group = iommu_group_get(&pdev->dev);

        return data->group != NULL;
}

/*
 * Generic device_group call-back function. It just allocates one
 * iommu-group per device.
 */
struct iommu_group *generic_device_group(struct device *dev)
{
        return iommu_group_alloc();
}
EXPORT_SYMBOL_GPL(generic_device_group);

/*
 * Use standard PCI bus topology, isolation features, and DMA alias quirks
 * to find or create an IOMMU group for a device.
 */
struct iommu_group *pci_device_group(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct group_for_pci_data data;
        struct pci_bus *bus;
        struct iommu_group *group = NULL;
        u64 devfns[4] = { 0 };

        if (WARN_ON(!dev_is_pci(dev)))
                return ERR_PTR(-EINVAL);

        /*
         * Find the upstream DMA alias for the device.  A device must not
         * be aliased due to topology in order to have its own IOMMU group.
         * If we find an alias along the way that already belongs to a
         * group, use it.
         */
        if (pci_for_each_dma_alias(pdev, get_pci_alias_or_group, &data))
                return data.group;

        pdev = data.pdev;

        /*
         * Continue upstream from the point of minimum IOMMU granularity
         * due to aliases to the point where devices are protected from
         * peer-to-peer DMA by PCI ACS.  Again, if we find an existing
         * group, use it.
         */
        for (bus = pdev->bus; !pci_is_root_bus(bus); bus = bus->parent) {
                if (!bus->self)
                        continue;

                if (pci_acs_path_enabled(bus->self, NULL, REQ_ACS_FLAGS))
                        break;

                pdev = bus->self;

                group = iommu_group_get(&pdev->dev);
                if (group)
                        return group;
        }

        /*
         * Look for existing groups on device aliases.  If we alias another
         * device or another device aliases us, use the same group.
         */
        group = get_pci_alias_group(pdev, (unsigned long *)devfns);
        if (group)
                return group;

        /*
         * Look for existing groups on non-isolated functions on the same
         * slot and aliases of those funcions, if any.  No need to clear
         * the search bitmap, the tested devfns are still valid.
         */
        group = get_pci_function_alias_group(pdev, (unsigned long *)devfns);
        if (group)
                return group;

        /* No shared group found, allocate new */
        return iommu_group_alloc();
}
EXPORT_SYMBOL_GPL(pci_device_group);

/* Get the IOMMU group for device on fsl-mc bus */
struct iommu_group *fsl_mc_device_group(struct device *dev)
{
        struct device *cont_dev = fsl_mc_cont_dev(dev);
        struct iommu_group *group;

        group = iommu_group_get(cont_dev);
        if (!group)
                group = iommu_group_alloc();
        return group;
}
EXPORT_SYMBOL_GPL(fsl_mc_device_group);

static int iommu_get_def_domain_type(struct device *dev)
{
        const struct iommu_ops *ops = dev->bus->iommu_ops;

        if (dev_is_pci(dev) && to_pci_dev(dev)->untrusted)
                return IOMMU_DOMAIN_DMA;

        if (ops->def_domain_type)
                return ops->def_domain_type(dev);

        return 0;
}

static int iommu_group_alloc_default_domain(struct bus_type *bus,
                                            struct iommu_group *group,
                                            unsigned int type)
{
        struct iommu_domain *dom;

        dom = __iommu_domain_alloc(bus, type);
        if (!dom && type != IOMMU_DOMAIN_DMA) {
                dom = __iommu_domain_alloc(bus, IOMMU_DOMAIN_DMA);
                if (dom)
                        pr_warn("Failed to allocate default IOMMU domain of type %u for group %s - Falling back to IOMMU_DOMAIN_DMA",
                                type, group->name);
        }

        if (!dom)
                return -ENOMEM;

        group->default_domain = dom;
        if (!group->domain)
                group->domain = dom;
        return 0;
}

static int iommu_alloc_default_domain(struct iommu_group *group,
                                      struct device *dev)
{
        unsigned int type;

        if (group->default_domain)
                return 0;

        type = iommu_get_def_domain_type(dev) ? : iommu_def_domain_type;

        return iommu_group_alloc_default_domain(dev->bus, group, type);
}

/**
 * iommu_group_get_for_dev - Find or create the IOMMU group for a device
 * @dev: target device
 *
 * This function is intended to be called by IOMMU drivers and extended to
 * support common, bus-defined algorithms when determining or creating the
 * IOMMU group for a device.  On success, the caller will hold a reference
 * to the returned IOMMU group, which will already include the provided
 * device.  The reference should be released with iommu_group_put().
 */
static struct iommu_group *iommu_group_get_for_dev(struct device *dev)
{
        const struct iommu_ops *ops = dev->bus->iommu_ops;
        struct iommu_group *group;
        int ret;

        group = iommu_group_get(dev);
        if (group)
                return group;

        if (!ops)
                return ERR_PTR(-EINVAL);

        group = ops->device_group(dev);
        if (WARN_ON_ONCE(group == NULL))
                return ERR_PTR(-EINVAL);

        if (IS_ERR(group))
                return group;

        ret = iommu_group_add_device(group, dev);
        if (ret)
                goto out_put_group;

        return group;

out_put_group:
        iommu_group_put(group);

        return ERR_PTR(ret);
}

struct iommu_domain *iommu_group_default_domain(struct iommu_group *group)
{
        return group->default_domain;
}

static int probe_iommu_group(struct device *dev, void *data)
{
        struct list_head *group_list = data;
        struct iommu_group *group;
        int ret;

        /* Device is probed already if in a group */
        group = iommu_group_get(dev);
        if (group) {
                iommu_group_put(group);
                return 0;
        }

        ret = __iommu_probe_device(dev, group_list);
        if (ret == -ENODEV)
                ret = 0;

        return ret;
}

static int remove_iommu_group(struct device *dev, void *data)
{
        iommu_release_device(dev);

        return 0;
}

static int iommu_bus_notifier(struct notifier_block *nb,
                              unsigned long action, void *data)
{
        unsigned long group_action = 0;
        struct device *dev = data;
        struct iommu_group *group;

        /*
         * ADD/DEL call into iommu driver ops if provided, which may
         * result in ADD/DEL notifiers to group->notifier
         */
        if (action == BUS_NOTIFY_ADD_DEVICE) {
                int ret;

                ret = iommu_probe_device(dev);
                return (ret) ? NOTIFY_DONE : NOTIFY_OK;
        } else if (action == BUS_NOTIFY_REMOVED_DEVICE) {
                iommu_release_device(dev);
                return NOTIFY_OK;
        }

        /*
         * Remaining BUS_NOTIFYs get filtered and republished to the
         * group, if anyone is listening
         */
        group = iommu_group_get(dev);
        if (!group)
                return 0;

        switch (action) {
        case BUS_NOTIFY_BIND_DRIVER:
                group_action = IOMMU_GROUP_NOTIFY_BIND_DRIVER;
                break;
        case BUS_NOTIFY_BOUND_DRIVER:
                group_action = IOMMU_GROUP_NOTIFY_BOUND_DRIVER;
                break;
        case BUS_NOTIFY_UNBIND_DRIVER:
                group_action = IOMMU_GROUP_NOTIFY_UNBIND_DRIVER;
                break;
        case BUS_NOTIFY_UNBOUND_DRIVER:
                group_action = IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER;
                break;
        }

        if (group_action)
                blocking_notifier_call_chain(&group->notifier,
                                             group_action, dev);

        iommu_group_put(group);
        return 0;
}

struct __group_domain_type {
        struct device *dev;
        unsigned int type;
};

static int probe_get_default_domain_type(struct device *dev, void *data)
{
        struct __group_domain_type *gtype = data;
        unsigned int type = iommu_get_def_domain_type(dev);

        if (type) {
                if (gtype->type && gtype->type != type) {
                        dev_warn(dev, "Device needs domain type %s, but device %s in the same iommu group requires type %s - using default\n",
                                 iommu_domain_type_str(type),
                                 dev_name(gtype->dev),
                                 iommu_domain_type_str(gtype->type));
                        gtype->type = 0;
                }

                if (!gtype->dev) {
                        gtype->dev  = dev;
                        gtype->type = type;
                }
        }

        return 0;
}

static void probe_alloc_default_domain(struct bus_type *bus,
                                       struct iommu_group *group)
{
        struct __group_domain_type gtype;

        memset(&gtype, 0, sizeof(gtype));

        /* Ask for default domain requirements of all devices in the group */
        __iommu_group_for_each_dev(group, &gtype,
                                   probe_get_default_domain_type);

        if (!gtype.type)
                gtype.type = iommu_def_domain_type;

        iommu_group_alloc_default_domain(bus, group, gtype.type);

}

static int iommu_group_do_dma_attach(struct device *dev, void *data)
{
        struct iommu_domain *domain = data;
        int ret = 0;

        if (!iommu_is_attach_deferred(domain, dev))
                ret = __iommu_attach_device(domain, dev);

        return ret;
}

static int __iommu_group_dma_attach(struct iommu_group *group)
{
        return __iommu_group_for_each_dev(group, group->default_domain,
                                          iommu_group_do_dma_attach);
}

static int iommu_group_do_probe_finalize(struct device *dev, void *data)
{
        struct iommu_domain *domain = data;

        if (domain->ops->probe_finalize)
                domain->ops->probe_finalize(dev);

        return 0;
}

static void __iommu_group_dma_finalize(struct iommu_group *group)
{
        __iommu_group_for_each_dev(group, group->default_domain,
                                   iommu_group_do_probe_finalize);
}

static int iommu_do_create_direct_mappings(struct device *dev, void *data)
{
        struct iommu_group *group = data;

        iommu_create_device_direct_mappings(group, dev);

        return 0;
}

static int iommu_group_create_direct_mappings(struct iommu_group *group)
{
        return __iommu_group_for_each_dev(group, group,
                                          iommu_do_create_direct_mappings);
}

int bus_iommu_probe(struct bus_type *bus)
{
        struct iommu_group *group, *next;
        LIST_HEAD(group_list);
        int ret;

        /*
         * This code-path does not allocate the default domain when
         * creating the iommu group, so do it after the groups are
         * created.
         */
        ret = bus_for_each_dev(bus, NULL, &group_list, probe_iommu_group);
        if (ret)
                return ret;

        list_for_each_entry_safe(group, next, &group_list, entry) {
                /* Remove item from the list */
                list_del_init(&group->entry);

                mutex_lock(&group->mutex);

                /* Try to allocate default domain */
                probe_alloc_default_domain(bus, group);

                if (!group->default_domain) {
                        mutex_unlock(&group->mutex);
                        continue;
                }

                iommu_group_create_direct_mappings(group);

                ret = __iommu_group_dma_attach(group);

                mutex_unlock(&group->mutex);

                if (ret)
                        break;

                __iommu_group_dma_finalize(group);
        }

        return ret;
}

static int iommu_bus_init(struct bus_type *bus, const struct iommu_ops *ops)
{
        struct notifier_block *nb;
        int err;

        nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
        if (!nb)
                return -ENOMEM;

        nb->notifier_call = iommu_bus_notifier;

        err = bus_register_notifier(bus, nb);
        if (err)
                goto out_free;

        err = bus_iommu_probe(bus);
        if (err)
                goto out_err;


        return 0;

out_err:
        /* Clean up */
        bus_for_each_dev(bus, NULL, NULL, remove_iommu_group);
        bus_unregister_notifier(bus, nb);

out_free:
        kfree(nb);

        return err;
}

/**
 * bus_set_iommu - set iommu-callbacks for the bus
 * @bus: bus.
 * @ops: the callbacks provided by the iommu-driver
 *
 * This function is called by an iommu driver to set the iommu methods
 * used for a particular bus. Drivers for devices on that bus can use
 * the iommu-api after these ops are registered.
 * This special function is needed because IOMMUs are usually devices on
 * the bus itself, so the iommu drivers are not initialized when the bus
 * is set up. With this function the iommu-driver can set the iommu-ops
 * afterwards.
 */
int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops)
{
        int err;

        if (ops == NULL) {
                bus->iommu_ops = NULL;
                return 0;
        }

        if (bus->iommu_ops != NULL)
                return -EBUSY;

        bus->iommu_ops = ops;

        /* Do IOMMU specific setup for this bus-type */
        err = iommu_bus_init(bus, ops);
        if (err)
                bus->iommu_ops = NULL;

        return err;
}
EXPORT_SYMBOL_GPL(bus_set_iommu);

bool iommu_present(struct bus_type *bus)
{
        return bus->iommu_ops != NULL;
}
EXPORT_SYMBOL_GPL(iommu_present);

bool iommu_capable(struct bus_type *bus, enum iommu_cap cap)
{
        if (!bus->iommu_ops || !bus->iommu_ops->capable)
                return false;

        return bus->iommu_ops->capable(cap);
}
EXPORT_SYMBOL_GPL(iommu_capable);

/**
 * iommu_set_fault_handler() - set a fault handler for an iommu domain
 * @domain: iommu domain
 * @handler: fault handler
 * @token: user data, will be passed back to the fault handler
 *
 * This function should be used by IOMMU users which want to be notified
 * whenever an IOMMU fault happens.
 *
 * The fault handler itself should return 0 on success, and an appropriate
 * error code otherwise.
 */
void iommu_set_fault_handler(struct iommu_domain *domain,
                                        iommu_fault_handler_t handler,
                                        void *token)
{
        BUG_ON(!domain);

        domain->handler = handler;
        domain->handler_token = token;
}
EXPORT_SYMBOL_GPL(iommu_set_fault_handler);

static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
                                                 unsigned type)
{
        struct iommu_domain *domain;

        if (bus == NULL || bus->iommu_ops == NULL)
                return NULL;

        domain = bus->iommu_ops->domain_alloc(type);
        if (!domain)
                return NULL;

        domain->ops  = bus->iommu_ops;
        domain->type = type;
        /* Assume all sizes by default; the driver may override this later */
        domain->pgsize_bitmap  = bus->iommu_ops->pgsize_bitmap;

        /* Temporarily avoid -EEXIST while drivers still get their own cookies */
        if (iommu_is_dma_domain(domain) && !domain->iova_cookie && iommu_get_dma_cookie(domain)) {
                iommu_domain_free(domain);
                domain = NULL;
        }
        return domain;
}

struct iommu_domain *iommu_domain_alloc(struct bus_type *bus)
{
        return __iommu_domain_alloc(bus, IOMMU_DOMAIN_UNMANAGED);
}
EXPORT_SYMBOL_GPL(iommu_domain_alloc);

void iommu_domain_free(struct iommu_domain *domain)
{
        iommu_put_dma_cookie(domain);
        domain->ops->domain_free(domain);
}
EXPORT_SYMBOL_GPL(iommu_domain_free);

static int __iommu_attach_device(struct iommu_domain *domain,
                                 struct device *dev)
{
        int ret;

        if (unlikely(domain->ops->attach_dev == NULL))
                return -ENODEV;

        ret = domain->ops->attach_dev(domain, dev);
        if (!ret)
                trace_attach_device_to_domain(dev);
        return ret;
}

int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
{
        struct iommu_group *group;
        int ret;

        group = iommu_group_get(dev);
        if (!group)
                return -ENODEV;

        /*
         * Lock the group to make sure the device-count doesn't
         * change while we are attaching
         */
        mutex_lock(&group->mutex);
        ret = -EINVAL;
        if (iommu_group_device_count(group) != 1)
                goto out_unlock;

        ret = __iommu_attach_group(domain, group);

out_unlock:
        mutex_unlock(&group->mutex);
        iommu_group_put(group);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_attach_device);

int iommu_deferred_attach(struct device *dev, struct iommu_domain *domain)
{
        const struct iommu_ops *ops = domain->ops;

        if (ops->is_attach_deferred && ops->is_attach_deferred(domain, dev))
                return __iommu_attach_device(domain, dev);

        return 0;
}

/*
 * Check flags and other user provided data for valid combinations. We also
 * make sure no reserved fields or unused flags are set. This is to ensure
 * not breaking userspace in the future when these fields or flags are used.
 */
static int iommu_check_cache_invl_data(struct iommu_cache_invalidate_info *info)
{
        u32 mask;
        int i;

        if (info->version != IOMMU_CACHE_INVALIDATE_INFO_VERSION_1)
                return -EINVAL;

        mask = (1 << IOMMU_CACHE_INV_TYPE_NR) - 1;
        if (info->cache & ~mask)
                return -EINVAL;

        if (info->granularity >= IOMMU_INV_GRANU_NR)
                return -EINVAL;

        switch (info->granularity) {
        case IOMMU_INV_GRANU_ADDR:
                if (info->cache & IOMMU_CACHE_INV_TYPE_PASID)
                        return -EINVAL;

                mask = IOMMU_INV_ADDR_FLAGS_PASID |
                        IOMMU_INV_ADDR_FLAGS_ARCHID |
                        IOMMU_INV_ADDR_FLAGS_LEAF;

                if (info->granu.addr_info.flags & ~mask)
                        return -EINVAL;
                break;
        case IOMMU_INV_GRANU_PASID:
                mask = IOMMU_INV_PASID_FLAGS_PASID |
                        IOMMU_INV_PASID_FLAGS_ARCHID;
                if (info->granu.pasid_info.flags & ~mask)
                        return -EINVAL;

                break;
        case IOMMU_INV_GRANU_DOMAIN:
                if (info->cache & IOMMU_CACHE_INV_TYPE_DEV_IOTLB)
                        return -EINVAL;
                break;
        default:
                return -EINVAL;
        }

        /* Check reserved padding fields */
        for (i = 0; i < sizeof(info->padding); i++) {
                if (info->padding[i])
                        return -EINVAL;
        }

        return 0;
}

int iommu_uapi_cache_invalidate(struct iommu_domain *domain, struct device *dev,
                                void __user *uinfo)
{
        struct iommu_cache_invalidate_info inv_info = { 0 };
        u32 minsz;
        int ret;

        if (unlikely(!domain->ops->cache_invalidate))
                return -ENODEV;

        /*
         * No new spaces can be added before the variable sized union, the
         * minimum size is the offset to the union.
         */
        minsz = offsetof(struct iommu_cache_invalidate_info, granu);

        /* Copy minsz from user to get flags and argsz */
        if (copy_from_user(&inv_info, uinfo, minsz))
                return -EFAULT;

        /* Fields before the variable size union are mandatory */
        if (inv_info.argsz < minsz)
                return -EINVAL;

        /* PASID and address granu require additional info beyond minsz */
        if (inv_info.granularity == IOMMU_INV_GRANU_PASID &&
            inv_info.argsz < offsetofend(struct iommu_cache_invalidate_info, granu.pasid_info))
                return -EINVAL;

        if (inv_info.granularity == IOMMU_INV_GRANU_ADDR &&
            inv_info.argsz < offsetofend(struct iommu_cache_invalidate_info, granu.addr_info))
                return -EINVAL;

        /*
         * User might be using a newer UAPI header which has a larger data
         * size, we shall support the existing flags within the current
         * size. Copy the remaining user data _after_ minsz but not more
         * than the current kernel supported size.
         */
        if (copy_from_user((void *)&inv_info + minsz, uinfo + minsz,
                           min_t(u32, inv_info.argsz, sizeof(inv_info)) - minsz))
                return -EFAULT;

        /* Now the argsz is validated, check the content */
        ret = iommu_check_cache_invl_data(&inv_info);
        if (ret)
                return ret;

        return domain->ops->cache_invalidate(domain, dev, &inv_info);
}
EXPORT_SYMBOL_GPL(iommu_uapi_cache_invalidate);

static int iommu_check_bind_data(struct iommu_gpasid_bind_data *data)
{
        u64 mask;
        int i;

        if (data->version != IOMMU_GPASID_BIND_VERSION_1)
                return -EINVAL;

        /* Check the range of supported formats */
        if (data->format >= IOMMU_PASID_FORMAT_LAST)
                return -EINVAL;

        /* Check all flags */
        mask = IOMMU_SVA_GPASID_VAL;
        if (data->flags & ~mask)
                return -EINVAL;

        /* Check reserved padding fields */
        for (i = 0; i < sizeof(data->padding); i++) {
                if (data->padding[i])
                        return -EINVAL;
        }

        return 0;
}

static int iommu_sva_prepare_bind_data(void __user *udata,
                                       struct iommu_gpasid_bind_data *data)
{
        u32 minsz;

        /*
         * No new spaces can be added before the variable sized union, the
         * minimum size is the offset to the union.
         */
        minsz = offsetof(struct iommu_gpasid_bind_data, vendor);

        /* Copy minsz from user to get flags and argsz */
        if (copy_from_user(data, udata, minsz))
                return -EFAULT;

        /* Fields before the variable size union are mandatory */
        if (data->argsz < minsz)
                return -EINVAL;
        /*
         * User might be using a newer UAPI header, we shall let IOMMU vendor
         * driver decide on what size it needs. Since the guest PASID bind data
         * can be vendor specific, larger argsz could be the result of extension
         * for one vendor but it should not affect another vendor.
         * Copy the remaining user data _after_ minsz
         */
        if (copy_from_user((void *)data + minsz, udata + minsz,
                           min_t(u32, data->argsz, sizeof(*data)) - minsz))
                return -EFAULT;

        return iommu_check_bind_data(data);
}

int iommu_uapi_sva_bind_gpasid(struct iommu_domain *domain, struct device *dev,
                               void __user *udata)
{
        struct iommu_gpasid_bind_data data = { 0 };
        int ret;

        if (unlikely(!domain->ops->sva_bind_gpasid))
                return -ENODEV;

        ret = iommu_sva_prepare_bind_data(udata, &data);
        if (ret)
                return ret;

        return domain->ops->sva_bind_gpasid(domain, dev, &data);
}
EXPORT_SYMBOL_GPL(iommu_uapi_sva_bind_gpasid);

int iommu_sva_unbind_gpasid(struct iommu_domain *domain, struct device *dev,
                             ioasid_t pasid)
{
        if (unlikely(!domain->ops->sva_unbind_gpasid))
                return -ENODEV;

        return domain->ops->sva_unbind_gpasid(dev, pasid);
}
EXPORT_SYMBOL_GPL(iommu_sva_unbind_gpasid);

int iommu_uapi_sva_unbind_gpasid(struct iommu_domain *domain, struct device *dev,
                                 void __user *udata)
{
        struct iommu_gpasid_bind_data data = { 0 };
        int ret;

        if (unlikely(!domain->ops->sva_bind_gpasid))
                return -ENODEV;

        ret = iommu_sva_prepare_bind_data(udata, &data);
        if (ret)
                return ret;

        return iommu_sva_unbind_gpasid(domain, dev, data.hpasid);
}
EXPORT_SYMBOL_GPL(iommu_uapi_sva_unbind_gpasid);

static void __iommu_detach_device(struct iommu_domain *domain,
                                  struct device *dev)
{
        if (iommu_is_attach_deferred(domain, dev))
                return;

        if (unlikely(domain->ops->detach_dev == NULL))
                return;

        domain->ops->detach_dev(domain, dev);
        trace_detach_device_from_domain(dev);
}

void iommu_detach_device(struct iommu_domain *domain, struct device *dev)
{
        struct iommu_group *group;

        group = iommu_group_get(dev);
        if (!group)
                return;

        mutex_lock(&group->mutex);
        if (iommu_group_device_count(group) != 1) {
                WARN_ON(1);
                goto out_unlock;
        }

        __iommu_detach_group(domain, group);

out_unlock:
        mutex_unlock(&group->mutex);
        iommu_group_put(group);
}
EXPORT_SYMBOL_GPL(iommu_detach_device);

struct iommu_domain *iommu_get_domain_for_dev(struct device *dev)
{
        struct iommu_domain *domain;
        struct iommu_group *group;

        group = iommu_group_get(dev);
        if (!group)
                return NULL;

        domain = group->domain;

        iommu_group_put(group);

        return domain;
}
EXPORT_SYMBOL_GPL(iommu_get_domain_for_dev);

/*
 * For IOMMU_DOMAIN_DMA implementations which already provide their own
 * guarantees that the group and its default domain are valid and correct.
 */
struct iommu_domain *iommu_get_dma_domain(struct device *dev)
{
        return dev->iommu_group->default_domain;
}

/*
 * IOMMU groups are really the natural working unit of the IOMMU, but
 * the IOMMU API works on domains and devices.  Bridge that gap by
 * iterating over the devices in a group.  Ideally we'd have a single
 * device which represents the requestor ID of the group, but we also
 * allow IOMMU drivers to create policy defined minimum sets, where
 * the physical hardware may be able to distiguish members, but we
 * wish to group them at a higher level (ex. untrusted multi-function
 * PCI devices).  Thus we attach each device.
 */
static int iommu_group_do_attach_device(struct device *dev, void *data)
{
        struct iommu_domain *domain = data;

        return __iommu_attach_device(domain, dev);
}

static int __iommu_attach_group(struct iommu_domain *domain,
                                struct iommu_group *group)
{
        int ret;

        if (group->default_domain && group->domain != group->default_domain)
                return -EBUSY;

        ret = __iommu_group_for_each_dev(group, domain,
                                         iommu_group_do_attach_device);
        if (ret == 0)
                group->domain = domain;

        return ret;
}

int iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group)
{
        int ret;

        mutex_lock(&group->mutex);
        ret = __iommu_attach_group(domain, group);
        mutex_unlock(&group->mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_attach_group);

static int iommu_group_do_detach_device(struct device *dev, void *data)
{
        struct iommu_domain *domain = data;

        __iommu_detach_device(domain, dev);

        return 0;
}

static void __iommu_detach_group(struct iommu_domain *domain,
                                 struct iommu_group *group)
{
        int ret;

        if (!group->default_domain) {
                __iommu_group_for_each_dev(group, domain,
                                           iommu_group_do_detach_device);
                group->domain = NULL;
                return;
        }

        if (group->domain == group->default_domain)
                return;

        /* Detach by re-attaching to the default domain */
        ret = __iommu_group_for_each_dev(group, group->default_domain,
                                         iommu_group_do_attach_device);
        if (ret != 0)
                WARN_ON(1);
        else
                group->domain = group->default_domain;
}

void iommu_detach_group(struct iommu_domain *domain, struct iommu_group *group)
{
        mutex_lock(&group->mutex);
        __iommu_detach_group(domain, group);
        mutex_unlock(&group->mutex);
}
EXPORT_SYMBOL_GPL(iommu_detach_group);

phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova)
{
        if (domain->type == IOMMU_DOMAIN_IDENTITY)
                return iova;

        if (domain->type == IOMMU_DOMAIN_BLOCKED)
                return 0;

        return domain->ops->iova_to_phys(domain, iova);
}
EXPORT_SYMBOL_GPL(iommu_iova_to_phys);

static size_t iommu_pgsize(struct iommu_domain *domain, unsigned long iova,
                           phys_addr_t paddr, size_t size, size_t *count)
{
        unsigned int pgsize_idx, pgsize_idx_next;
        unsigned long pgsizes;
        size_t offset, pgsize, pgsize_next;
        unsigned long addr_merge = paddr | iova;

        /* Page sizes supported by the hardware and small enough for @size */
        pgsizes = domain->pgsize_bitmap & GENMASK(__fls(size), 0);

        /* Constrain the page sizes further based on the maximum alignment */
        if (likely(addr_merge))
                pgsizes &= GENMASK(__ffs(addr_merge), 0);

        /* Make sure we have at least one suitable page size */
        BUG_ON(!pgsizes);

        /* Pick the biggest page size remaining */
        pgsize_idx = __fls(pgsizes);
        pgsize = BIT(pgsize_idx);
        if (!count)
                return pgsize;

        /* Find the next biggest support page size, if it exists */
        pgsizes = domain->pgsize_bitmap & ~GENMASK(pgsize_idx, 0);
        if (!pgsizes)
                goto out_set_count;

        pgsize_idx_next = __ffs(pgsizes);
        pgsize_next = BIT(pgsize_idx_next);

        /*
         * There's no point trying a bigger page size unless the virtual
         * and physical addresses are similarly offset within the larger page.
         */
        if ((iova ^ paddr) & (pgsize_next - 1))
                goto out_set_count;

        /* Calculate the offset to the next page size alignment boundary */
        offset = pgsize_next - (addr_merge & (pgsize_next - 1));

        /*
         * If size is big enough to accommodate the larger page, reduce
         * the number of smaller pages.
         */
        if (offset + pgsize_next <= size)
                size = offset;

out_set_count:
        *count = size >> pgsize_idx;
        return pgsize;
}

static int __iommu_map_pages(struct iommu_domain *domain, unsigned long iova,
                             phys_addr_t paddr, size_t size, int prot,
                             gfp_t gfp, size_t *mapped)
{
        const struct iommu_ops *ops = domain->ops;
        size_t pgsize, count;
        int ret;

        pgsize = iommu_pgsize(domain, iova, paddr, size, &count);

        pr_debug("mapping: iova 0x%lx pa %pa pgsize 0x%zx count %zu\n",
                 iova, &paddr, pgsize, count);

        if (ops->map_pages) {
                ret = ops->map_pages(domain, iova, paddr, pgsize, count, prot,
                                     gfp, mapped);
        } else {
                ret = ops->map(domain, iova, paddr, pgsize, prot, gfp);
                *mapped = ret ? 0 : pgsize;
        }

        return ret;
}

static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
                       phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
{
        const struct iommu_ops *ops = domain->ops;
        unsigned long orig_iova = iova;
        unsigned int min_pagesz;
        size_t orig_size = size;
        phys_addr_t orig_paddr = paddr;
        int ret = 0;

        if (unlikely(!(ops->map || ops->map_pages) ||
                     domain->pgsize_bitmap == 0UL))
                return -ENODEV;

        if (unlikely(!(domain->type & __IOMMU_DOMAIN_PAGING)))
                return -EINVAL;

        /* find out the minimum page size supported */
        min_pagesz = 1 << __ffs(domain->pgsize_bitmap);

        /*
         * both the virtual address and the physical one, as well as
         * the size of the mapping, must be aligned (at least) to the
         * size of the smallest page supported by the hardware
         */
        if (!IS_ALIGNED(iova | paddr | size, min_pagesz)) {
                pr_err("unaligned: iova 0x%lx pa %pa size 0x%zx min_pagesz 0x%x\n",
                       iova, &paddr, size, min_pagesz);
                return -EINVAL;
        }

        pr_debug("map: iova 0x%lx pa %pa size 0x%zx\n", iova, &paddr, size);

        while (size) {
                size_t mapped = 0;

                ret = __iommu_map_pages(domain, iova, paddr, size, prot, gfp,
                                        &mapped);
                /*
                 * Some pages may have been mapped, even if an error occurred,
                 * so we should account for those so they can be unmapped.
                 */
                size -= mapped;

                if (ret)
                        break;

                iova += mapped;
                paddr += mapped;
        }

        /* unroll mapping in case something went wrong */
        if (ret)
                iommu_unmap(domain, orig_iova, orig_size - size);
        else
                trace_map(orig_iova, orig_paddr, orig_size);

        return ret;
}

static int _iommu_map(struct iommu_domain *domain, unsigned long iova,
                      phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
{
        const struct iommu_ops *ops = domain->ops;
        int ret;

        ret = __iommu_map(domain, iova, paddr, size, prot, gfp);
        if (ret == 0 && ops->iotlb_sync_map)
                ops->iotlb_sync_map(domain, iova, size);

        return ret;
}

int iommu_map(struct iommu_domain *domain, unsigned long iova,
              phys_addr_t paddr, size_t size, int prot)
{
        might_sleep();
        return _iommu_map(domain, iova, paddr, size, prot, GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(iommu_map);

int iommu_map_atomic(struct iommu_domain *domain, unsigned long iova,
              phys_addr_t paddr, size_t size, int prot)
{
        return _iommu_map(domain, iova, paddr, size, prot, GFP_ATOMIC);
}
EXPORT_SYMBOL_GPL(iommu_map_atomic);

static size_t __iommu_unmap_pages(struct iommu_domain *domain,
                                  unsigned long iova, size_t size,
                                  struct iommu_iotlb_gather *iotlb_gather)
{
        const struct iommu_ops *ops = domain->ops;
        size_t pgsize, count;

        pgsize = iommu_pgsize(domain, iova, iova, size, &count);
        return ops->unmap_pages ?
               ops->unmap_pages(domain, iova, pgsize, count, iotlb_gather) :
               ops->unmap(domain, iova, pgsize, iotlb_gather);
}

static size_t __iommu_unmap(struct iommu_domain *domain,
                            unsigned long iova, size_t size,
                            struct iommu_iotlb_gather *iotlb_gather)
{
        const struct iommu_ops *ops = domain->ops;
        size_t unmapped_page, unmapped = 0;
        unsigned long orig_iova = iova;
        unsigned int min_pagesz;

        if (unlikely(!(ops->unmap || ops->unmap_pages) ||
                     domain->pgsize_bitmap == 0UL))
                return 0;

        if (unlikely(!(domain->type & __IOMMU_DOMAIN_PAGING)))
                return 0;

        /* find out the minimum page size supported */
        min_pagesz = 1 << __ffs(domain->pgsize_bitmap);

        /*
         * The virtual address, as well as the size of the mapping, must be
         * aligned (at least) to the size of the smallest page supported
         * by the hardware
         */
        if (!IS_ALIGNED(iova | size, min_pagesz)) {
                pr_err("unaligned: iova 0x%lx size 0x%zx min_pagesz 0x%x\n",
                       iova, size, min_pagesz);
                return 0;
        }

        pr_debug("unmap this: iova 0x%lx size 0x%zx\n", iova, size);

        /*
         * Keep iterating until we either unmap 'size' bytes (or more)
         * or we hit an area that isn't mapped.
         */
        while (unmapped < size) {
                unmapped_page = __iommu_unmap_pages(domain, iova,
                                                    size - unmapped,
                                                    iotlb_gather);
                if (!unmapped_page)
                        break;

                pr_debug("unmapped: iova 0x%lx size 0x%zx\n",
                         iova, unmapped_page);

                iova += unmapped_page;
                unmapped += unmapped_page;
        }

        trace_unmap(orig_iova, size, unmapped);
        return unmapped;
}

size_t iommu_unmap(struct iommu_domain *domain,
                   unsigned long iova, size_t size)
{
        struct iommu_iotlb_gather iotlb_gather;
        size_t ret;

        iommu_iotlb_gather_init(&iotlb_gather);
        ret = __iommu_unmap(domain, iova, size, &iotlb_gather);
        iommu_iotlb_sync(domain, &iotlb_gather);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_unmap);

size_t iommu_unmap_fast(struct iommu_domain *domain,
                        unsigned long iova, size_t size,
                        struct iommu_iotlb_gather *iotlb_gather)
{
        return __iommu_unmap(domain, iova, size, iotlb_gather);
}
EXPORT_SYMBOL_GPL(iommu_unmap_fast);

static ssize_t __iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
                struct scatterlist *sg, unsigned int nents, int prot,
                gfp_t gfp)
{
        const struct iommu_ops *ops = domain->ops;
        size_t len = 0, mapped = 0;
        phys_addr_t start;
        unsigned int i = 0;
        int ret;

        while (i <= nents) {
                phys_addr_t s_phys = sg_phys(sg);

                if (len && s_phys != start + len) {
                        ret = __iommu_map(domain, iova + mapped, start,
                                        len, prot, gfp);

                        if (ret)
                                goto out_err;

                        mapped += len;
                        len = 0;
                }

                if (len) {
                        len += sg->length;
                } else {
                        len = sg->length;
                        start = s_phys;
                }

                if (++i < nents)
                        sg = sg_next(sg);
        }

        if (ops->iotlb_sync_map)
                ops->iotlb_sync_map(domain, iova, mapped);
        return mapped;

out_err:
        /* undo mappings already done */
        iommu_unmap(domain, iova, mapped);

        return ret;
}

ssize_t iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
                     struct scatterlist *sg, unsigned int nents, int prot)
{
        might_sleep();
        return __iommu_map_sg(domain, iova, sg, nents, prot, GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(iommu_map_sg);

ssize_t iommu_map_sg_atomic(struct iommu_domain *domain, unsigned long iova,
                    struct scatterlist *sg, unsigned int nents, int prot)
{
        return __iommu_map_sg(domain, iova, sg, nents, prot, GFP_ATOMIC);
}

/**
 * report_iommu_fault() - report about an IOMMU fault to the IOMMU framework
 * @domain: the iommu domain where the fault has happened
 * @dev: the device where the fault has happened
 * @iova: the faulting address
 * @flags: mmu fault flags (e.g. IOMMU_FAULT_READ/IOMMU_FAULT_WRITE/...)
 *
 * This function should be called by the low-level IOMMU implementations
 * whenever IOMMU faults happen, to allow high-level users, that are
 * interested in such events, to know about them.
 *
 * This event may be useful for several possible use cases:
 * - mere logging of the event
 * - dynamic TLB/PTE loading
 * - if restarting of the faulting device is required
 *
 * Returns 0 on success and an appropriate error code otherwise (if dynamic
 * PTE/TLB loading will one day be supported, implementations will be able
 * to tell whether it succeeded or not according to this return value).
 *
 * Specifically, -ENOSYS is returned if a fault handler isn't installed
 * (though fault handlers can also return -ENOSYS, in case they want to
 * elicit the default behavior of the IOMMU drivers).
 */
int report_iommu_fault(struct iommu_domain *domain, struct device *dev,
                       unsigned long iova, int flags)
{
        int ret = -ENOSYS;

        /*
         * if upper layers showed interest and installed a fault handler,
         * invoke it.
         */
        if (domain->handler)
                ret = domain->handler(domain, dev, iova, flags,
                                                domain->handler_token);

        trace_io_page_fault(dev, iova, flags);
        return ret;
}
EXPORT_SYMBOL_GPL(report_iommu_fault);

static int __init iommu_init(void)
{
        iommu_group_kset = kset_create_and_add("iommu_groups",
                                               NULL, kernel_kobj);
        BUG_ON(!iommu_group_kset);

        iommu_debugfs_setup();

        return 0;
}
core_initcall(iommu_init);

int iommu_enable_nesting(struct iommu_domain *domain)
{
        if (domain->type != IOMMU_DOMAIN_UNMANAGED)
                return -EINVAL;
        if (!domain->ops->enable_nesting)
                return -EINVAL;
        return domain->ops->enable_nesting(domain);
}
EXPORT_SYMBOL_GPL(iommu_enable_nesting);

int iommu_set_pgtable_quirks(struct iommu_domain *domain,
                unsigned long quirk)
{
        if (domain->type != IOMMU_DOMAIN_UNMANAGED)
                return -EINVAL;
        if (!domain->ops->set_pgtable_quirks)
                return -EINVAL;
        return domain->ops->set_pgtable_quirks(domain, quirk);
}
EXPORT_SYMBOL_GPL(iommu_set_pgtable_quirks);

void iommu_get_resv_regions(struct device *dev, struct list_head *list)
{
        const struct iommu_ops *ops = dev->bus->iommu_ops;

        if (ops && ops->get_resv_regions)
                ops->get_resv_regions(dev, list);
}

void iommu_put_resv_regions(struct device *dev, struct list_head *list)
{
        const struct iommu_ops *ops = dev->bus->iommu_ops;

        if (ops && ops->put_resv_regions)
                ops->put_resv_regions(dev, list);
}

/**
 * generic_iommu_put_resv_regions - Reserved region driver helper
 * @dev: device for which to free reserved regions
 * @list: reserved region list for device
 *
 * IOMMU drivers can use this to implement their .put_resv_regions() callback
 * for simple reservations. Memory allocated for each reserved region will be
 * freed. If an IOMMU driver allocates additional resources per region, it is
 * going to have to implement a custom callback.
 */
void generic_iommu_put_resv_regions(struct device *dev, struct list_head *list)
{
        struct iommu_resv_region *entry, *next;

        list_for_each_entry_safe(entry, next, list, list)
                kfree(entry);
}
EXPORT_SYMBOL(generic_iommu_put_resv_regions);

struct iommu_resv_region *iommu_alloc_resv_region(phys_addr_t start,
                                                  size_t length, int prot,
                                                  enum iommu_resv_type type)
{
        struct iommu_resv_region *region;

        region = kzalloc(sizeof(*region), GFP_KERNEL);
        if (!region)
                return NULL;

        INIT_LIST_HEAD(&region->list);
        region->start = start;
        region->length = length;
        region->prot = prot;
        region->type = type;
        return region;
}
EXPORT_SYMBOL_GPL(iommu_alloc_resv_region);

void iommu_set_default_passthrough(bool cmd_line)
{
        if (cmd_line)
                iommu_cmd_line |= IOMMU_CMD_LINE_DMA_API;
        iommu_def_domain_type = IOMMU_DOMAIN_IDENTITY;
}

void iommu_set_default_translated(bool cmd_line)
{
        if (cmd_line)
                iommu_cmd_line |= IOMMU_CMD_LINE_DMA_API;
        iommu_def_domain_type = IOMMU_DOMAIN_DMA;
}

bool iommu_default_passthrough(void)
{
        return iommu_def_domain_type == IOMMU_DOMAIN_IDENTITY;
}
EXPORT_SYMBOL_GPL(iommu_default_passthrough);

const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
{
        const struct iommu_ops *ops = NULL;
        struct iommu_device *iommu;

        spin_lock(&iommu_device_lock);
        list_for_each_entry(iommu, &iommu_device_list, list)
                if (iommu->fwnode == fwnode) {
                        ops = iommu->ops;
                        break;
                }
        spin_unlock(&iommu_device_lock);
        return ops;
}

int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
                      const struct iommu_ops *ops)
{
        struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);

        if (fwspec)
                return ops == fwspec->ops ? 0 : -EINVAL;

        if (!dev_iommu_get(dev))
                return -ENOMEM;

        /* Preallocate for the overwhelmingly common case of 1 ID */
        fwspec = kzalloc(struct_size(fwspec, ids, 1), GFP_KERNEL);
        if (!fwspec)
                return -ENOMEM;

        of_node_get(to_of_node(iommu_fwnode));
        fwspec->iommu_fwnode = iommu_fwnode;
        fwspec->ops = ops;
        dev_iommu_fwspec_set(dev, fwspec);
        return 0;
}
EXPORT_SYMBOL_GPL(iommu_fwspec_init);

void iommu_fwspec_free(struct device *dev)
{
        struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);

        if (fwspec) {
                fwnode_handle_put(fwspec->iommu_fwnode);
                kfree(fwspec);
                dev_iommu_fwspec_set(dev, NULL);
        }
}
EXPORT_SYMBOL_GPL(iommu_fwspec_free);

int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids)
{
        struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
        int i, new_num;

        if (!fwspec)
                return -EINVAL;

        new_num = fwspec->num_ids + num_ids;
        if (new_num > 1) {
                fwspec = krealloc(fwspec, struct_size(fwspec, ids, new_num),
                                  GFP_KERNEL);
                if (!fwspec)
                        return -ENOMEM;

                dev_iommu_fwspec_set(dev, fwspec);
        }

        for (i = 0; i < num_ids; i++)
                fwspec->ids[fwspec->num_ids + i] = ids[i];

        fwspec->num_ids = new_num;
        return 0;
}
EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);

/*
 * Per device IOMMU features.
 */
int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features feat)
{
        if (dev->iommu && dev->iommu->iommu_dev) {
                const struct iommu_ops *ops = dev->iommu->iommu_dev->ops;

                if (ops->dev_enable_feat)
                        return ops->dev_enable_feat(dev, feat);
        }

        return -ENODEV;
}
EXPORT_SYMBOL_GPL(iommu_dev_enable_feature);

/*
 * The device drivers should do the necessary cleanups before calling this.
 * For example, before disabling the aux-domain feature, the device driver
 * should detach all aux-domains. Otherwise, this will return -EBUSY.
 */
int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat)
{
        if (dev->iommu && dev->iommu->iommu_dev) {
                const struct iommu_ops *ops = dev->iommu->iommu_dev->ops;

                if (ops->dev_disable_feat)
                        return ops->dev_disable_feat(dev, feat);
        }

        return -EBUSY;
}
EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);

bool iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features feat)
{
        if (dev->iommu && dev->iommu->iommu_dev) {
                const struct iommu_ops *ops = dev->iommu->iommu_dev->ops;

                if (ops->dev_feat_enabled)
                        return ops->dev_feat_enabled(dev, feat);
        }

        return false;
}
EXPORT_SYMBOL_GPL(iommu_dev_feature_enabled);

/*
 * Aux-domain specific attach/detach.
 *
 * Only works if iommu_dev_feature_enabled(dev, IOMMU_DEV_FEAT_AUX) returns
 * true. Also, as long as domains are attached to a device through this
 * interface, any tries to call iommu_attach_device() should fail
 * (iommu_detach_device() can't fail, so we fail when trying to re-attach).
 * This should make us safe against a device being attached to a guest as a
 * whole while there are still pasid users on it (aux and sva).
 */
int iommu_aux_attach_device(struct iommu_domain *domain, struct device *dev)
{
        int ret = -ENODEV;

        if (domain->ops->aux_attach_dev)
                ret = domain->ops->aux_attach_dev(domain, dev);

        if (!ret)
                trace_attach_device_to_domain(dev);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_aux_attach_device);

void iommu_aux_detach_device(struct iommu_domain *domain, struct device *dev)
{
        if (domain->ops->aux_detach_dev) {
                domain->ops->aux_detach_dev(domain, dev);
                trace_detach_device_from_domain(dev);
        }
}
EXPORT_SYMBOL_GPL(iommu_aux_detach_device);

int iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev)
{
        int ret = -ENODEV;

        if (domain->ops->aux_get_pasid)
                ret = domain->ops->aux_get_pasid(domain, dev);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_aux_get_pasid);

/**
 * iommu_sva_bind_device() - Bind a process address space to a device
 * @dev: the device
 * @mm: the mm to bind, caller must hold a reference to it
 *
 * Create a bond between device and address space, allowing the device to access
 * the mm using the returned PASID. If a bond already exists between @device and
 * @mm, it is returned and an additional reference is taken. Caller must call
 * iommu_sva_unbind_device() to release each reference.
 *
 * iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called first, to
 * initialize the required SVA features.
 *
 * On error, returns an ERR_PTR value.
 */
struct iommu_sva *
iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
{
        struct iommu_group *group;
        struct iommu_sva *handle = ERR_PTR(-EINVAL);
        const struct iommu_ops *ops = dev->bus->iommu_ops;

        if (!ops || !ops->sva_bind)
                return ERR_PTR(-ENODEV);

        group = iommu_group_get(dev);
        if (!group)
                return ERR_PTR(-ENODEV);

        /* Ensure device count and domain don't change while we're binding */
        mutex_lock(&group->mutex);

        /*
         * To keep things simple, SVA currently doesn't support IOMMU groups
         * with more than one device. Existing SVA-capable systems are not
         * affected by the problems that required IOMMU groups (lack of ACS
         * isolation, device ID aliasing and other hardware issues).
         */
        if (iommu_group_device_count(group) != 1)
                goto out_unlock;

        handle = ops->sva_bind(dev, mm, drvdata);

out_unlock:
        mutex_unlock(&group->mutex);
        iommu_group_put(group);

        return handle;
}
EXPORT_SYMBOL_GPL(iommu_sva_bind_device);

/**
 * iommu_sva_unbind_device() - Remove a bond created with iommu_sva_bind_device
 * @handle: the handle returned by iommu_sva_bind_device()
 *
 * Put reference to a bond between device and address space. The device should
 * not be issuing any more transaction for this PASID. All outstanding page
 * requests for this PASID must have been flushed to the IOMMU.
 */
void iommu_sva_unbind_device(struct iommu_sva *handle)
{
        struct iommu_group *group;
        struct device *dev = handle->dev;
        const struct iommu_ops *ops = dev->bus->iommu_ops;

        if (!ops || !ops->sva_unbind)
                return;

        group = iommu_group_get(dev);
        if (!group)
                return;

        mutex_lock(&group->mutex);
        ops->sva_unbind(handle);
        mutex_unlock(&group->mutex);

        iommu_group_put(group);
}
EXPORT_SYMBOL_GPL(iommu_sva_unbind_device);

u32 iommu_sva_get_pasid(struct iommu_sva *handle)
{
        const struct iommu_ops *ops = handle->dev->bus->iommu_ops;

        if (!ops || !ops->sva_get_pasid)
                return IOMMU_PASID_INVALID;

        return ops->sva_get_pasid(handle);
}
EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);

/*
 * Changes the default domain of an iommu group that has *only* one device
 *
 * @group: The group for which the default domain should be changed
 * @prev_dev: The device in the group (this is used to make sure that the device
 *       hasn't changed after the caller has called this function)
 * @type: The type of the new default domain that gets associated with the group
 *
 * Returns 0 on success and error code on failure
 *
 * Note:
 * 1. Presently, this function is called only when user requests to change the
 *    group's default domain type through /sys/kernel/iommu_groups/<grp_id>/type
 *    Please take a closer look if intended to use for other purposes.
 */
static int iommu_change_dev_def_domain(struct iommu_group *group,
                                       struct device *prev_dev, int type)
{
        struct iommu_domain *prev_dom;
        struct group_device *grp_dev;
        int ret, dev_def_dom;
        struct device *dev;

        mutex_lock(&group->mutex);

        if (group->default_domain != group->domain) {
                dev_err_ratelimited(prev_dev, "Group not assigned to default domain\n");
                ret = -EBUSY;
                goto out;
        }

        /*
         * iommu group wasn't locked while acquiring device lock in
         * iommu_group_store_type(). So, make sure that the device count hasn't
         * changed while acquiring device lock.
         *
         * Changing default domain of an iommu group with two or more devices
         * isn't supported because there could be a potential deadlock. Consider
         * the following scenario. T1 is trying to acquire device locks of all
         * the devices in the group and before it could acquire all of them,
         * there could be another thread T2 (from different sub-system and use
         * case) that has already acquired some of the device locks and might be
         * waiting for T1 to release other device locks.
         */
        if (iommu_group_device_count(group) != 1) {
                dev_err_ratelimited(prev_dev, "Cannot change default domain: Group has more than one device\n");
                ret = -EINVAL;
                goto out;
        }

        /* Since group has only one device */
        grp_dev = list_first_entry(&group->devices, struct group_device, list);
        dev = grp_dev->dev;

        if (prev_dev != dev) {
                dev_err_ratelimited(prev_dev, "Cannot change default domain: Device has been changed\n");
                ret = -EBUSY;
                goto out;
        }

        prev_dom = group->default_domain;
        if (!prev_dom) {
                ret = -EINVAL;
                goto out;
        }

        dev_def_dom = iommu_get_def_domain_type(dev);
        if (!type) {
                /*
                 * If the user hasn't requested any specific type of domain and
                 * if the device supports both the domains, then default to the
                 * domain the device was booted with
                 */
                type = dev_def_dom ? : iommu_def_domain_type;
        } else if (dev_def_dom && type != dev_def_dom) {
                dev_err_ratelimited(prev_dev, "Device cannot be in %s domain\n",
                                    iommu_domain_type_str(type));
                ret = -EINVAL;
                goto out;
        }

        /*
         * Switch to a new domain only if the requested domain type is different
         * from the existing default domain type
         */
        if (prev_dom->type == type) {
                ret = 0;
                goto out;
        }

        /* We can bring up a flush queue without tearing down the domain */
        if (type == IOMMU_DOMAIN_DMA_FQ && prev_dom->type == IOMMU_DOMAIN_DMA) {
                ret = iommu_dma_init_fq(prev_dom);
                if (!ret)
                        prev_dom->type = IOMMU_DOMAIN_DMA_FQ;
                goto out;
        }

        /* Sets group->default_domain to the newly allocated domain */
        ret = iommu_group_alloc_default_domain(dev->bus, group, type);
        if (ret)
                goto out;

        ret = iommu_create_device_direct_mappings(group, dev);
        if (ret)
                goto free_new_domain;

        ret = __iommu_attach_device(group->default_domain, dev);
        if (ret)
                goto free_new_domain;

        group->domain = group->default_domain;

        /*
         * Release the mutex here because ops->probe_finalize() call-back of
         * some vendor IOMMU drivers calls arm_iommu_attach_device() which
         * in-turn might call back into IOMMU core code, where it tries to take
         * group->mutex, resulting in a deadlock.
         */
        mutex_unlock(&group->mutex);

        /* Make sure dma_ops is appropriatley set */
        iommu_group_do_probe_finalize(dev, group->default_domain);
        iommu_domain_free(prev_dom);
        return 0;

free_new_domain:
        iommu_domain_free(group->default_domain);
        group->default_domain = prev_dom;
        group->domain = prev_dom;

out:
        mutex_unlock(&group->mutex);

        return ret;
}

/*
 * Changing the default domain through sysfs requires the users to unbind the
 * drivers from the devices in the iommu group, except for a DMA -> DMA-FQ
 * transition. Return failure if this isn't met.
 *
 * We need to consider the race between this and the device release path.
 * device_lock(dev) is used here to guarantee that the device release path
 * will not be entered at the same time.
 */
static ssize_t iommu_group_store_type(struct iommu_group *group,
                                      const char *buf, size_t count)
{
        struct group_device *grp_dev;
        struct device *dev;
        int ret, req_type;

        if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
                return -EACCES;

        if (WARN_ON(!group))
                return -EINVAL;

        if (sysfs_streq(buf, "identity"))
                req_type = IOMMU_DOMAIN_IDENTITY;
        else if (sysfs_streq(buf, "DMA"))
                req_type = IOMMU_DOMAIN_DMA;
        else if (sysfs_streq(buf, "DMA-FQ"))
                req_type = IOMMU_DOMAIN_DMA_FQ;
        else if (sysfs_streq(buf, "auto"))
                req_type = 0;
        else
                return -EINVAL;

        /*
         * Lock/Unlock the group mutex here before device lock to
         * 1. Make sure that the iommu group has only one device (this is a
         *    prerequisite for step 2)
         * 2. Get struct *dev which is needed to lock device
         */
        mutex_lock(&group->mutex);
        if (iommu_group_device_count(group) != 1) {
                mutex_unlock(&group->mutex);
                pr_err_ratelimited("Cannot change default domain: Group has more than one device\n");
                return -EINVAL;
        }

        /* Since group has only one device */
        grp_dev = list_first_entry(&group->devices, struct group_device, list);
        dev = grp_dev->dev;
        get_device(dev);

        /*
         * Don't hold the group mutex because taking group mutex first and then
         * the device lock could potentially cause a deadlock as below. Assume
         * two threads T1 and T2. T1 is trying to change default domain of an
         * iommu group and T2 is trying to hot unplug a device or release [1] VF
         * of a PCIe device which is in the same iommu group. T1 takes group
         * mutex and before it could take device lock assume T2 has taken device
         * lock and is yet to take group mutex. Now, both the threads will be
         * waiting for the other thread to release lock. Below, lock order was
         * suggested.
         * device_lock(dev);
         *      mutex_lock(&group->mutex);
         *              iommu_change_dev_def_domain();
         *      mutex_unlock(&group->mutex);
         * device_unlock(dev);
         *
         * [1] Typical device release path
         * device_lock() from device/driver core code
         *  -> bus_notifier()
         *   -> iommu_bus_notifier()
         *    -> iommu_release_device()
         *     -> ops->release_device() vendor driver calls back iommu core code
         *      -> mutex_lock() from iommu core code
         */
        mutex_unlock(&group->mutex);

        /* Check if the device in the group still has a driver bound to it */
        device_lock(dev);
        if (device_is_bound(dev) && !(req_type == IOMMU_DOMAIN_DMA_FQ &&
            group->default_domain->type == IOMMU_DOMAIN_DMA)) {
                pr_err_ratelimited("Device is still bound to driver\n");
                ret = -EBUSY;
                goto out;
        }

        ret = iommu_change_dev_def_domain(group, dev, req_type);
        ret = ret ?: count;

out:
        device_unlock(dev);
        put_device(dev);

        return ret;
}