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/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 <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 = true;
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)

static void iommu_set_cmd_line_dma_api(void)
{
    iommu_cmd_line |= IOMMU_CMD_LINE_DMA_API;
}

static bool iommu_cmd_line_dma_api(void)
{
    return !!(iommu_cmd_line & IOMMU_CMD_LINE_DMA_API);
}

static int iommu_alloc_default_domain(struct iommu_group *group, struct device *dev);
static struct iommu_domain *iommu_domain_alloc_ext(struct bus_type *bus, unsigned type);
static int iommu_attach_device_ext(struct iommu_domain *domain, struct device *dev);
static int iommu_attach_group_ext(struct iommu_domain *domain, struct iommu_group *group);
static void iommu_detach_group_ext(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);

#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:
            return "Translated";
        default:
            return "Unknown";
    }
}

static int __init iommu_subsys_init(void)
{
    bool cmd_line = iommu_cmd_line_dma_api();

    if (!cmd_line) {
        if (IS_ENABLED(CONFIG_IOMMU_DEFAULT_PASSTHROUGH)) {
            iommu_set_default_passthrough(false);
        } else {
            iommu_set_default_translated(false);
        }

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

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

    return 0;
}
subsys_initcall(iommu_subsys_init);

int iommu_device_register(struct iommu_device *iommu)
{
    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)
{
    struct dev_iommu *param = dev->iommu;

    dev->iommu = NULL;
    if (param->fwspec) {
        fwnode_handle_put(param->fwspec->iommu_fwnode);
        kfree(param->fwspec);
    }
    kfree(param);
}

static int iommu_probe_device_ext(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_ext(dev, NULL);
    if (ret) {
        goto err_out;
    }

    group = iommu_group_get(dev);
    if (!group) {
        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.
     */
    iommu_alloc_default_domain(group, dev);

    if (group->default_domain) {
        ret = iommu_attach_device_ext(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)
{
    return kstrtobool(str, &iommu_dma_strict);
}
early_param("iommu.strict", iommu_dma_setup);

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";

    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;
        }
    }
    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, 0444, iommu_group_show_type, NULL);

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 || domain->type != IOMMU_DOMAIN_DMA) {
        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;

        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;

            phys_addr = iommu_iova_to_phys(domain, addr);
            if (phys_addr) {
                continue;
            }

            ret = iommu_map(domain, addr, addr, pg_size, entry->prot);
            if (ret) {
                goto out;
            }
        }
    }

    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));
    while (1) {
        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++);
                continue;
            }
            goto err_free_name;
        }
        break;
    }

    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_ext(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_ext(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_ext(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;
    unsigned int type = 0;

    if (ops->def_domain_type) {
        type = ops->def_domain_type(dev);
    }

    return (type == 0) ? iommu_def_domain_type : type;
}

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_ext(bus, type);
    if (!dom && type != IOMMU_DOMAIN_DMA) {
        dom = iommu_domain_alloc_ext(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;
    }

    if (!iommu_dma_strict) {
        int attr = 1;
        iommu_domain_set_attr(dom, DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE, &attr);
    }

    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);

    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_ext(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;
        default:
            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)
{
    const struct iommu_ops *ops = dev->bus->iommu_ops;
    struct __group_domain_type *gtype = data;
    unsigned int type = 0;

    if (ops->def_domain_type) {
        type = ops->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_ext(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_ext(domain, dev);
    }

    return ret;
}

static int iommu_group_dma_attach_ext(struct iommu_group *group)
{
    return iommu_group_for_each_dev_ext(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_ext(struct iommu_group *group)
{
    iommu_group_for_each_dev_ext(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_ext(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_ext(group);

        mutex_unlock(&group->mutex);

        if (ret) {
            break;
        }

        iommu_group_dma_finalize_ext(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_ext(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;

    return domain;
}

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

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

static int iommu_attach_device_ext(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_ext(domain, group);

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

    return ret;
}
EXPORT_SYMBOL_GPL(iommu_attach_device);

/*
 * 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);
    /* Don't break detach if iommu shared by more than one master */
    if (iommu_group_device_count(group) < 1) {
        WARN_ON(1);
        goto out_unlock;
    }

    iommu_detach_group_ext(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_ext(domain, dev);
}

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

    if (!group->default_domain) {
        iommu_group_for_each_dev_ext(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_ext(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_ext(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 (unlikely(domain->ops->iova_to_phys == NULL)) {
        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_ext(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_ext(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_ext(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_ext(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_ext(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_ext(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_ext(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_ext(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_ext(domain, iova, size, iotlb_gather);
}
EXPORT_SYMBOL_GPL(iommu_unmap_fast);

static size_t iommu_map_sg_ext(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;

    if (ops->map_sg) {
        ret = ops->map_sg(domain, iova, sg, nents, prot, gfp, &mapped);

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

        if (ret) {
            goto out_err;
        }

        return mapped;
    }

    while (i <= nents) {
        phys_addr_t s_phys = sg_phys(sg);
        if (len && s_phys != start + len) {
            ret = iommu_map_ext(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);
    }

#ifdef IOMMU_TLB_SHOT_ENTIRE
    if (domain->ops->flush_iotlb_all && (prot & IOMMU_TLB_SHOT_ENTIRE)) {
        domain->ops->flush_iotlb_all(domain);
    }
#endif

    return mapped;

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

    return 0;
}

size_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_ext(domain, iova, sg, nents, prot, GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(iommu_map_sg);

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

int iommu_domain_window_enable(struct iommu_domain *domain, u32 wnd_nr, phys_addr_t paddr, u64 size, int prot)
{
    if (unlikely(domain->ops->domain_window_enable == NULL)) {
        return -ENODEV;
    }

    return domain->ops->domain_window_enable(domain, wnd_nr, paddr, size, prot);
}
EXPORT_SYMBOL_GPL(iommu_domain_window_enable);

void iommu_domain_window_disable(struct iommu_domain *domain, u32 wnd_nr)
{
    if (unlikely(domain->ops->domain_window_disable == NULL)) {
        return;
    }

    return domain->ops->domain_window_disable(domain, wnd_nr);
}
EXPORT_SYMBOL_GPL(iommu_domain_window_disable);

/**
 * 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_domain_get_attr(struct iommu_domain *domain, enum iommu_attr attr, void *data)
{
    struct iommu_domain_geometry *geometry;
    bool *paging;
    int ret = 0;

    switch (attr) {
        case DOMAIN_ATTR_GEOMETRY:
            geometry = data;
            *geometry = domain->geometry;

            break;
        case DOMAIN_ATTR_PAGING:
            paging = data;
            *paging = (domain->pgsize_bitmap != 0UL);
            break;
        default:
            if (!domain->ops->domain_get_attr) {
                return -EINVAL;
            }

            ret = domain->ops->domain_get_attr(domain, attr, data);
    }

    return ret;
}
EXPORT_SYMBOL_GPL(iommu_domain_get_attr);

int iommu_domain_set_attr(struct iommu_domain *domain, enum iommu_attr attr, void *data)
{
    int ret = 0;

    if (domain->ops->domain_set_attr == NULL) {
        return -EINVAL;
    }

    ret = domain->ops->domain_set_attr(domain, attr, data);
    return ret;
}
EXPORT_SYMBOL_GPL(iommu_domain_set_attr);

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_set_cmd_line_dma_api();
    }

    iommu_def_domain_type = IOMMU_DOMAIN_IDENTITY;
}

void iommu_set_default_translated(bool cmd_line)
{
    if (cmd_line) {
        iommu_set_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.
 */
bool iommu_dev_has_feature(struct device *dev, enum iommu_dev_features feat)
{
    const struct iommu_ops *ops = dev->bus->iommu_ops;

    if (ops && ops->dev_has_feat) {
        return ops->dev_has_feat(dev, feat);
    }

    return false;
}
EXPORT_SYMBOL_GPL(iommu_dev_has_feature);

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.
 *
 * Returns 0 on success, or an error value
 */
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);