// 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/amba/bus.h>
#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/host1x_context_bus.h>
#include <linux/iommu.h>
#include <linux/iommufd.h>
#include <linux/idr.h>
#include <linux/err.h>
#include <linux/pci.h>
#include <linux/pci-ats.h>
#include <linux/bitops.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/fsl/mc.h>
#include <linux/module.h>
#include <linux/cc_platform.h>
#include <linux/cdx/cdx_bus.h>
#include <trace/events/iommu.h>
#include <linux/sched/mm.h>
#include <linux/msi.h>
#include <uapi/linux/iommufd.h>

#include "dma-iommu.h"
#include "iommu-priv.h"

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

/* Tags used with xa_tag_pointer() in group->pasid_array */
enum { IOMMU_PASID_ARRAY_DOMAIN = 0, IOMMU_PASID_ARRAY_HANDLE = 1 };

struct iommu_group {
        struct kobject kobj;
        struct kobject *devices_kobj;
        struct list_head devices;
        struct xarray pasid_array;
        struct mutex mutex;
        void *iommu_data;
        void (*iommu_data_release)(void *iommu_data);
        char *name;
        int id;
        struct iommu_domain *default_domain;
        struct iommu_domain *blocking_domain;
        /*
         * During a group device reset, @resetting_domain points to the physical
         * domain, while @domain points to the attached domain before the reset.
         */
        struct iommu_domain *resetting_domain;
        struct iommu_domain *domain;
        struct list_head entry;
        unsigned int owner_cnt;
        void *owner;
};

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

/* Iterate over each struct group_device in a struct iommu_group */
#define for_each_group_device(group, pos) \
        list_for_each_entry(pos, &(group)->devices, list)

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 bus_iommu_probe(const struct bus_type *bus);
static int iommu_bus_notifier(struct notifier_block *nb,
                              unsigned long action, void *data);
static void iommu_release_device(struct device *dev);
static int __iommu_attach_device(struct iommu_domain *domain,
                                 struct device *dev, struct iommu_domain *old);
static int __iommu_attach_group(struct iommu_domain *domain,
                                struct iommu_group *group);
static struct iommu_domain *__iommu_paging_domain_alloc_flags(struct device *dev,
                                                       unsigned int type,
                                                       unsigned int flags);

enum {
        IOMMU_SET_DOMAIN_MUST_SUCCEED = 1 << 0,
};

static int __iommu_device_set_domain(struct iommu_group *group,
                                     struct device *dev,
                                     struct iommu_domain *new_domain,
                                     struct iommu_domain *old_domain,
                                     unsigned int flags);
static int __iommu_group_set_domain_internal(struct iommu_group *group,
                                             struct iommu_domain *new_domain,
                                             unsigned int flags);
static int __iommu_group_set_domain(struct iommu_group *group,
                                    struct iommu_domain *new_domain)
{
        return __iommu_group_set_domain_internal(group, new_domain, 0);
}
static void __iommu_group_set_domain_nofail(struct iommu_group *group,
                                            struct iommu_domain *new_domain)
{
        WARN_ON(__iommu_group_set_domain_internal(
                group, new_domain, IOMMU_SET_DOMAIN_MUST_SUCCEED));
}

static int iommu_setup_default_domain(struct iommu_group *group,
                                      int target_type);
static int iommu_create_device_direct_mappings(struct iommu_domain *domain,
                                               struct device *dev);
static ssize_t iommu_group_store_type(struct iommu_group *group,
                                      const char *buf, size_t count);
static struct group_device *iommu_group_alloc_device(struct iommu_group *group,
                                                     struct device *dev);
static void __iommu_group_free_device(struct iommu_group *group,
                                      struct group_device *grp_dev);
static void iommu_domain_init(struct iommu_domain *domain, unsigned int type,
                              const struct iommu_ops *ops);

#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);

static const struct bus_type * const iommu_buses[] = {
        &platform_bus_type,
#ifdef CONFIG_PCI
        &pci_bus_type,
#endif
#ifdef CONFIG_ARM_AMBA
        &amba_bustype,
#endif
#ifdef CONFIG_FSL_MC_BUS
        &fsl_mc_bus_type,
#endif
#ifdef CONFIG_TEGRA_HOST1X_CONTEXT_BUS
        &host1x_context_device_bus_type,
#endif
#ifdef CONFIG_CDX_BUS
        &cdx_bus_type,
#endif
};

/*
 * 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";
        case IOMMU_DOMAIN_PLATFORM:
                return "Platform";
        default:
                return "Unknown";
        }
}

static int __init iommu_subsys_init(void)
{
        struct notifier_block *nb;

        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)" : "");

        nb = kzalloc_objs(*nb, ARRAY_SIZE(iommu_buses));
        if (!nb)
                return -ENOMEM;

        iommu_debug_init();

        for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++) {
                nb[i].notifier_call = iommu_bus_notifier;
                bus_register_notifier(iommu_buses[i], &nb[i]);
        }

        return 0;
}
subsys_initcall(iommu_subsys_init);

static int remove_iommu_group(struct device *dev, void *data)
{
        if (dev->iommu && dev->iommu->iommu_dev == data)
                iommu_release_device(dev);

        return 0;
}

/**
 * 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)
{
        int err = 0;

        /* 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 = dev_fwnode(hwdev);

        spin_lock(&iommu_device_lock);
        list_add_tail(&iommu->list, &iommu_device_list);
        spin_unlock(&iommu_device_lock);

        for (int i = 0; i < ARRAY_SIZE(iommu_buses) && !err; i++)
                err = bus_iommu_probe(iommu_buses[i]);
        if (err)
                iommu_device_unregister(iommu);
        else
                WRITE_ONCE(iommu->ready, true);
        return err;
}
EXPORT_SYMBOL_GPL(iommu_device_register);

void iommu_device_unregister(struct iommu_device *iommu)
{
        for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++)
                bus_for_each_dev(iommu_buses[i], NULL, iommu, remove_iommu_group);

        spin_lock(&iommu_device_lock);
        list_del(&iommu->list);
        spin_unlock(&iommu_device_lock);

        /* Pairs with the alloc in generic_single_device_group() */
        iommu_group_put(iommu->singleton_group);
        iommu->singleton_group = NULL;
}
EXPORT_SYMBOL_GPL(iommu_device_unregister);

#if IS_ENABLED(CONFIG_IOMMUFD_TEST)
void iommu_device_unregister_bus(struct iommu_device *iommu,
                                 const struct bus_type *bus,
                                 struct notifier_block *nb)
{
        bus_unregister_notifier(bus, nb);
        fwnode_remove_software_node(iommu->fwnode);
        iommu_device_unregister(iommu);
}
EXPORT_SYMBOL_GPL(iommu_device_unregister_bus);

/*
 * Register an iommu driver against a single bus. This is only used by iommufd
 * selftest to create a mock iommu driver. The caller must provide
 * some memory to hold a notifier_block.
 */
int iommu_device_register_bus(struct iommu_device *iommu,
                              const struct iommu_ops *ops,
                              const struct bus_type *bus,
                              struct notifier_block *nb)
{
        int err;

        iommu->ops = ops;
        nb->notifier_call = iommu_bus_notifier;
        err = bus_register_notifier(bus, nb);
        if (err)
                return err;

        iommu->fwnode = fwnode_create_software_node(NULL, NULL);
        if (IS_ERR(iommu->fwnode)) {
                bus_unregister_notifier(bus, nb);
                return PTR_ERR(iommu->fwnode);
        }

        spin_lock(&iommu_device_lock);
        list_add_tail(&iommu->list, &iommu_device_list);
        spin_unlock(&iommu_device_lock);

        err = bus_iommu_probe(bus);
        if (err) {
                iommu_device_unregister_bus(iommu, bus, nb);
                return err;
        }
        WRITE_ONCE(iommu->ready, true);
        return 0;
}
EXPORT_SYMBOL_GPL(iommu_device_register_bus);

int iommu_mock_device_add(struct device *dev, struct iommu_device *iommu)
{
        int rc;

        mutex_lock(&iommu_probe_device_lock);
        rc = iommu_fwspec_init(dev, iommu->fwnode);
        mutex_unlock(&iommu_probe_device_lock);

        if (rc)
                return rc;

        rc = device_add(dev);
        if (rc)
                iommu_fwspec_free(dev);
        return rc;
}
EXPORT_SYMBOL_GPL(iommu_mock_device_add);
#endif

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

        lockdep_assert_held(&iommu_probe_device_lock);

        if (param)
                return param;

        param = kzalloc_obj(*param);
        if (!param)
                return NULL;

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

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);
}

/*
 * Internal equivalent of device_iommu_mapped() for when we care that a device
 * actually has API ops, and don't want false positives from VFIO-only groups.
 */
static bool dev_has_iommu(struct device *dev)
{
        return dev->iommu && dev->iommu->iommu_dev;
}

static u32 dev_iommu_get_max_pasids(struct device *dev)
{
        u32 max_pasids = 0, bits = 0;
        int ret;

        if (dev_is_pci(dev)) {
                ret = pci_max_pasids(to_pci_dev(dev));
                if (ret > 0)
                        max_pasids = ret;
        } else {
                ret = device_property_read_u32(dev, "pasid-num-bits", &bits);
                if (!ret)
                        max_pasids = 1UL << bits;
        }

        return min_t(u32, max_pasids, dev->iommu->iommu_dev->max_pasids);
}

void dev_iommu_priv_set(struct device *dev, void *priv)
{
        /* FSL_PAMU does something weird */
        if (!IS_ENABLED(CONFIG_FSL_PAMU))
                lockdep_assert_held(&iommu_probe_device_lock);
        dev->iommu->priv = priv;
}
EXPORT_SYMBOL_GPL(dev_iommu_priv_set);

/*
 * Init the dev->iommu and dev->iommu_group in the struct device and get the
 * driver probed
 */
static int iommu_init_device(struct device *dev)
{
        const struct iommu_ops *ops;
        struct iommu_device *iommu_dev;
        struct iommu_group *group;
        int ret;

        if (!dev_iommu_get(dev))
                return -ENOMEM;
        /*
         * For FDT-based systems and ACPI IORT/VIOT, the common firmware parsing
         * is buried in the bus dma_configure path. Properly unpicking that is
         * still a big job, so for now just invoke the whole thing. The device
         * already having a driver bound means dma_configure has already run and
         * found no IOMMU to wait for, so there's no point calling it again.
         */
        if (!dev->iommu->fwspec && !dev->driver && dev->bus->dma_configure) {
                mutex_unlock(&iommu_probe_device_lock);
                dev->bus->dma_configure(dev);
                mutex_lock(&iommu_probe_device_lock);
                /* If another instance finished the job for us, skip it */
                if (!dev->iommu || dev->iommu_group)
                        return -ENODEV;
        }
        /*
         * At this point, relevant devices either now have a fwspec which will
         * match ops registered with a non-NULL fwnode, or we can reasonably
         * assume that only one of Intel, AMD, s390, PAMU or legacy SMMUv2 can
         * be present, and that any of their registered instances has suitable
         * ops for probing, and thus cheekily co-opt the same mechanism.
         */
        ops = iommu_fwspec_ops(dev->iommu->fwspec);
        if (!ops) {
                ret = -ENODEV;
                goto err_free;
        }

        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 err_module_put;
        }
        dev->iommu->iommu_dev = iommu_dev;

        ret = iommu_device_link(iommu_dev, dev);
        if (ret)
                goto err_release;

        group = ops->device_group(dev);
        if (WARN_ON_ONCE(group == NULL))
                group = ERR_PTR(-EINVAL);
        if (IS_ERR(group)) {
                ret = PTR_ERR(group);
                goto err_unlink;
        }
        dev->iommu_group = group;

        dev->iommu->max_pasids = dev_iommu_get_max_pasids(dev);
        if (ops->is_attach_deferred)
                dev->iommu->attach_deferred = ops->is_attach_deferred(dev);
        return 0;

err_unlink:
        iommu_device_unlink(iommu_dev, dev);
err_release:
        if (ops->release_device)
                ops->release_device(dev);
err_module_put:
        module_put(ops->owner);
err_free:
        dev->iommu->iommu_dev = NULL;
        dev_iommu_free(dev);
        return ret;
}

static void iommu_deinit_device(struct device *dev)
{
        struct iommu_group *group = dev->iommu_group;
        const struct iommu_ops *ops = dev_iommu_ops(dev);

        lockdep_assert_held(&group->mutex);

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

        /*
         * release_device() must stop using any attached domain on the device.
         * If there are still other devices in the group, they are not affected
         * by this callback.
         *
         * If the iommu driver provides release_domain, the core code ensures
         * that domain is attached prior to calling release_device. Drivers can
         * use this to enforce a translation on the idle iommu. Typically, the
         * global static blocked_domain is a good choice.
         *
         * Otherwise, the iommu driver must set the device to either an identity
         * or a blocking translation in release_device() and stop using any
         * domain pointer, as it is going to be freed.
         *
         * Regardless, if a delayed attach never occurred, then the release
         * should still avoid touching any hardware configuration either.
         */
        if (!dev->iommu->attach_deferred && ops->release_domain) {
                struct iommu_domain *release_domain = ops->release_domain;

                /*
                 * If the device requires direct mappings then it should not
                 * be parked on a BLOCKED domain during release as that would
                 * break the direct mappings.
                 */
                if (dev->iommu->require_direct && ops->identity_domain &&
                    release_domain == ops->blocked_domain)
                        release_domain = ops->identity_domain;

                release_domain->ops->attach_dev(release_domain, dev,
                                                group->domain);
        }

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

        /*
         * If this is the last driver to use the group then we must free the
         * domains before we do the module_put().
         */
        if (list_empty(&group->devices)) {
                if (group->default_domain) {
                        iommu_domain_free(group->default_domain);
                        group->default_domain = NULL;
                }
                if (group->blocking_domain) {
                        iommu_domain_free(group->blocking_domain);
                        group->blocking_domain = NULL;
                }
                group->domain = NULL;
        }

        /* Caller must put iommu_group */
        dev->iommu_group = NULL;
        module_put(ops->owner);
        dev_iommu_free(dev);
#ifdef CONFIG_IOMMU_DMA
        dev->dma_iommu = false;
#endif
}

static struct iommu_domain *pasid_array_entry_to_domain(void *entry)
{
        if (xa_pointer_tag(entry) == IOMMU_PASID_ARRAY_DOMAIN)
                return xa_untag_pointer(entry);
        return ((struct iommu_attach_handle *)xa_untag_pointer(entry))->domain;
}

DEFINE_MUTEX(iommu_probe_device_lock);

static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
{
        struct iommu_group *group;
        struct group_device *gdev;
        int ret;

        /*
         * Serialise to avoid races between IOMMU drivers registering in
         * parallel and/or the "replay" calls from ACPI/OF code via client
         * driver probe. Once the latter have been cleaned up we should
         * probably be able to use device_lock() here to minimise the scope,
         * but for now enforcing a simple global ordering is fine.
         */
        lockdep_assert_held(&iommu_probe_device_lock);

        /* Device is probed already if in a group */
        if (dev->iommu_group)
                return 0;

        ret = iommu_init_device(dev);
        if (ret)
                return ret;
        /*
         * And if we do now see any replay calls, they would indicate someone
         * misusing the dma_configure path outside bus code.
         */
        if (dev->driver)
                dev_WARN(dev, "late IOMMU probe at driver bind, something fishy here!\n");

        group = dev->iommu_group;
        gdev = iommu_group_alloc_device(group, dev);
        mutex_lock(&group->mutex);
        if (IS_ERR(gdev)) {
                ret = PTR_ERR(gdev);
                goto err_put_group;
        }

        /*
         * The gdev must be in the list before calling
         * iommu_setup_default_domain()
         */
        list_add_tail(&gdev->list, &group->devices);
        WARN_ON(group->default_domain && !group->domain);
        if (group->default_domain)
                iommu_create_device_direct_mappings(group->default_domain, dev);
        if (group->domain) {
                ret = __iommu_device_set_domain(group, dev, group->domain, NULL,
                                                0);
                if (ret)
                        goto err_remove_gdev;
        } else if (!group->default_domain && !group_list) {
                ret = iommu_setup_default_domain(group, 0);
                if (ret)
                        goto err_remove_gdev;
        } else if (!group->default_domain) {
                /*
                 * With a group_list argument we defer the default_domain setup
                 * to the caller by providing a de-duplicated list of groups
                 * that need further setup.
                 */
                if (list_empty(&group->entry))
                        list_add_tail(&group->entry, group_list);
        }

        if (group->default_domain)
                iommu_setup_dma_ops(dev, group->default_domain);

        mutex_unlock(&group->mutex);

        return 0;

err_remove_gdev:
        list_del(&gdev->list);
        __iommu_group_free_device(group, gdev);
err_put_group:
        iommu_deinit_device(dev);
        mutex_unlock(&group->mutex);
        iommu_group_put(group);

        return ret;
}

int iommu_probe_device(struct device *dev)
{
        const struct iommu_ops *ops;
        int ret;

        mutex_lock(&iommu_probe_device_lock);
        ret = __iommu_probe_device(dev, NULL);
        mutex_unlock(&iommu_probe_device_lock);
        if (ret)
                return ret;

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

        return 0;
}

static void __iommu_group_free_device(struct iommu_group *group,
                                      struct group_device *grp_dev)
{
        struct device *dev = grp_dev->dev;

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

        trace_remove_device_from_group(group->id, dev);

        /*
         * If the group has become empty then ownership must have been
         * released, and the current domain must be set back to NULL or
         * the default domain.
         */
        if (list_empty(&group->devices))
                WARN_ON(group->owner_cnt ||
                        group->domain != group->default_domain);

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

/* Remove the iommu_group from the struct device. */
static void __iommu_group_remove_device(struct device *dev)
{
        struct iommu_group *group = dev->iommu_group;
        struct group_device *device;

        mutex_lock(&group->mutex);
        for_each_group_device(group, device) {
                if (device->dev != dev)
                        continue;

                list_del(&device->list);
                __iommu_group_free_device(group, device);
                if (dev_has_iommu(dev))
                        iommu_deinit_device(dev);
                else
                        dev->iommu_group = NULL;
                break;
        }
        mutex_unlock(&group->mutex);

        /*
         * Pairs with the get in iommu_init_device() or
         * iommu_group_add_device()
         */
        iommu_group_put(group);
}

static void iommu_release_device(struct device *dev)
{
        struct iommu_group *group = dev->iommu_group;

        if (group)
                __iommu_group_remove_device(dev);

        /* Free any fwspec if no iommu_driver was ever attached */
        if (dev->iommu)
                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 sysfs_emit(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, GFP_KERNEL);
        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);
        for_each_group_device(group, device) {
                struct list_head dev_resv_regions;

                /*
                 * Non-API groups still expose reserved_regions in sysfs,
                 * so filter out calls that get here that way.
                 */
                if (!dev_has_iommu(device->dev))
                        break;

                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;
        int offset = 0;

        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) {
                offset += sysfs_emit_at(buf, offset, "0x%016llx 0x%016llx %s\n",
                                        (long long)region->start,
                                        (long long)(region->start +
                                                    region->length - 1),
                                        iommu_group_resv_type_string[region->type]);
                kfree(region);
        }

        return offset;
}

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

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

        return sysfs_emit(buf, "%s\n", 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_free(&iommu_group_ida, group->id);

        /* Domains are free'd by iommu_deinit_device() */
        WARN_ON(group->default_domain);
        WARN_ON(group->blocking_domain);

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

static const 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_obj(*group);
        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);
        xa_init(&group->pasid_array);

        ret = ida_alloc(&iommu_group_ida, 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) {
                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) {
                kobject_put(group->devices_kobj);
                return ERR_PTR(ret);
        }

        ret = iommu_group_create_file(group, &iommu_group_attr_type);
        if (ret) {
                kobject_put(group->devices_kobj);
                return ERR_PTR(ret);
        }

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

        return group;
}
EXPORT_SYMBOL_GPL(iommu_group_alloc);

/**
 * 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_domain *domain,
                                               struct device *dev)
{
        struct iommu_resv_region *entry;
        LIST_HEAD(mappings);
        unsigned long pg_size;
        int ret = 0;

        pg_size = domain->pgsize_bitmap ? 1UL << __ffs(domain->pgsize_bitmap) : 0;

        if (WARN_ON_ONCE(iommu_is_dma_domain(domain) && !pg_size))
                return -EINVAL;

        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 (entry->type == IOMMU_RESV_DIRECT)
                        dev->iommu->require_direct = 1;

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

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

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

                        if (addr == end)
                                goto map_end;

                        /*
                         * Return address by iommu_iova_to_phys for 0 is
                         * ambiguous. Offset to address 1 if addr is 0.
                         */
                        phys_addr = iommu_iova_to_phys(domain, addr ? addr : 1);
                        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, GFP_KERNEL);
                                if (ret)
                                        goto out;
                                map_size = 0;
                        }
                }

        }
out:
        iommu_put_resv_regions(dev, &mappings);

        return ret;
}

/* This is undone by __iommu_group_free_device() */
static struct group_device *iommu_group_alloc_device(struct iommu_group *group,
                                                     struct device *dev)
{
        int ret, i = 0;
        struct group_device *device;

        device = kzalloc_obj(*device);
        if (!device)
                return ERR_PTR(-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;
        }

        trace_add_device_to_group(group->id, dev);

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

        return device;

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 ERR_PTR(ret);
}

/**
 * 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)
{
        struct group_device *gdev;

        gdev = iommu_group_alloc_device(group, dev);
        if (IS_ERR(gdev))
                return PTR_ERR(gdev);

        iommu_group_ref_get(group);
        dev->iommu_group = group;

        mutex_lock(&group->mutex);
        list_add_tail(&gdev->list, &group->devices);
        mutex_unlock(&group->mutex);
        return 0;
}
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;

        if (!group)
                return;

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

        __iommu_group_remove_device(dev);
}
EXPORT_SYMBOL_GPL(iommu_group_remove_device);

#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_IOMMU_API)
/**
 * iommu_group_mutex_assert - Check device group mutex lock
 * @dev: the device that has group param set
 *
 * This function is called by an iommu driver to check whether it holds
 * group mutex lock for the given device or not.
 *
 * Note that this function must be called after device group param is set.
 */
void iommu_group_mutex_assert(struct device *dev)
{
        struct iommu_group *group = dev->iommu_group;

        lockdep_assert_held(&group->mutex);
}
EXPORT_SYMBOL_GPL(iommu_group_mutex_assert);
#endif

static struct device *iommu_group_first_dev(struct iommu_group *group)
{
        lockdep_assert_held(&group->mutex);
        return list_first_entry(&group->devices, struct group_device, list)->dev;
}

/**
 * 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.
 */
int iommu_group_for_each_dev(struct iommu_group *group, void *data,
                             int (*fn)(struct device *, void *))
{
        struct group_device *device;
        int ret = 0;

        mutex_lock(&group->mutex);
        for_each_group_device(group, device) {
                ret = fn(device->dev, data);
                if (ret)
                        break;
        }
        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_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);

/*
 * Generic device_group call-back function. It just allocates one
 * iommu-group per iommu driver instance shared by every device
 * probed by that iommu driver.
 */
struct iommu_group *generic_single_device_group(struct device *dev)
{
        struct iommu_device *iommu = dev->iommu->iommu_dev;

        if (!iommu->singleton_group) {
                struct iommu_group *group;

                group = iommu_group_alloc();
                if (IS_ERR(group))
                        return group;
                iommu->singleton_group = group;
        }
        return iommu_group_ref_get(iommu->singleton_group);
}
EXPORT_SYMBOL_GPL(generic_single_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 struct iommu_domain *__iommu_alloc_identity_domain(struct device *dev)
{
        const struct iommu_ops *ops = dev_iommu_ops(dev);
        struct iommu_domain *domain;

        if (ops->identity_domain)
                return ops->identity_domain;

        if (ops->domain_alloc_identity) {
                domain = ops->domain_alloc_identity(dev);
                if (IS_ERR(domain))
                        return domain;
        } else {
                return ERR_PTR(-EOPNOTSUPP);
        }

        iommu_domain_init(domain, IOMMU_DOMAIN_IDENTITY, ops);
        return domain;
}

static struct iommu_domain *
__iommu_group_alloc_default_domain(struct iommu_group *group, int req_type)
{
        struct device *dev = iommu_group_first_dev(group);
        struct iommu_domain *dom;

        if (group->default_domain && group->default_domain->type == req_type)
                return group->default_domain;

        /*
         * When allocating the DMA API domain assume that the driver is going to
         * use PASID and make sure the RID's domain is PASID compatible.
         */
        if (req_type & __IOMMU_DOMAIN_PAGING) {
                dom = __iommu_paging_domain_alloc_flags(dev, req_type,
                           dev->iommu->max_pasids ? IOMMU_HWPT_ALLOC_PASID : 0);

                /*
                 * If driver does not support PASID feature then
                 * try to allocate non-PASID domain
                 */
                if (PTR_ERR(dom) == -EOPNOTSUPP)
                        dom = __iommu_paging_domain_alloc_flags(dev, req_type, 0);

                return dom;
        }

        if (req_type == IOMMU_DOMAIN_IDENTITY)
                return __iommu_alloc_identity_domain(dev);

        return ERR_PTR(-EINVAL);
}

/*
 * req_type of 0 means "auto" which means to select a domain based on
 * iommu_def_domain_type or what the driver actually supports.
 */
static struct iommu_domain *
iommu_group_alloc_default_domain(struct iommu_group *group, int req_type)
{
        const struct iommu_ops *ops = dev_iommu_ops(iommu_group_first_dev(group));
        struct iommu_domain *dom;

        lockdep_assert_held(&group->mutex);

        /*
         * Allow legacy drivers to specify the domain that will be the default
         * domain. This should always be either an IDENTITY/BLOCKED/PLATFORM
         * domain. Do not use in new drivers.
         */
        if (ops->default_domain) {
                if (req_type != ops->default_domain->type)
                        return ERR_PTR(-EINVAL);
                return ops->default_domain;
        }

        if (req_type)
                return __iommu_group_alloc_default_domain(group, req_type);

        /* The driver gave no guidance on what type to use, try the default */
        dom = __iommu_group_alloc_default_domain(group, iommu_def_domain_type);
        if (!IS_ERR(dom))
                return dom;

        /* Otherwise IDENTITY and DMA_FQ defaults will try DMA */
        if (iommu_def_domain_type == IOMMU_DOMAIN_DMA)
                return ERR_PTR(-EINVAL);
        dom = __iommu_group_alloc_default_domain(group, IOMMU_DOMAIN_DMA);
        if (IS_ERR(dom))
                return dom;

        pr_warn("Failed to allocate default IOMMU domain of type %u for group %s - Falling back to IOMMU_DOMAIN_DMA",
                iommu_def_domain_type, group->name);
        return dom;
}

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;
        int ret;

        mutex_lock(&iommu_probe_device_lock);
        ret = __iommu_probe_device(dev, group_list);
        mutex_unlock(&iommu_probe_device_lock);
        if (ret == -ENODEV)
                ret = 0;

        return ret;
}

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

        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;
        }

        return 0;
}

/*
 * Combine the driver's chosen def_domain_type across all the devices in a
 * group. Drivers must give a consistent result.
 */
static int iommu_get_def_domain_type(struct iommu_group *group,
                                     struct device *dev, int cur_type)
{
        const struct iommu_ops *ops = dev_iommu_ops(dev);
        int type;

        if (ops->default_domain) {
                /*
                 * Drivers that declare a global static default_domain will
                 * always choose that.
                 */
                type = ops->default_domain->type;
        } else {
                if (ops->def_domain_type)
                        type = ops->def_domain_type(dev);
                else
                        return cur_type;
        }
        if (!type || cur_type == type)
                return cur_type;
        if (!cur_type)
                return type;

        dev_err_ratelimited(
                dev,
                "IOMMU driver error, requesting conflicting def_domain_type, %s and %s, for devices in group %u.\n",
                iommu_domain_type_str(cur_type), iommu_domain_type_str(type),
                group->id);

        /*
         * Try to recover, drivers are allowed to force IDENTITY or DMA, IDENTITY
         * takes precedence.
         */
        if (type == IOMMU_DOMAIN_IDENTITY)
                return type;
        return cur_type;
}

/*
 * A target_type of 0 will select the best domain type. 0 can be returned in
 * this case meaning the global default should be used.
 */
static int iommu_get_default_domain_type(struct iommu_group *group,
                                         int target_type)
{
        struct device *untrusted = NULL;
        struct group_device *gdev;
        int driver_type = 0;

        lockdep_assert_held(&group->mutex);

        /*
         * ARM32 drivers supporting CONFIG_ARM_DMA_USE_IOMMU can declare an
         * identity_domain and it will automatically become their default
         * domain. Later on ARM_DMA_USE_IOMMU will install its UNMANAGED domain.
         * Override the selection to IDENTITY.
         */
        if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) {
                static_assert(!(IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU) &&
                                IS_ENABLED(CONFIG_IOMMU_DMA)));
                driver_type = IOMMU_DOMAIN_IDENTITY;
        }

        for_each_group_device(group, gdev) {
                driver_type = iommu_get_def_domain_type(group, gdev->dev,
                                                        driver_type);

                if (dev_is_pci(gdev->dev) && to_pci_dev(gdev->dev)->untrusted) {
                        /*
                         * No ARM32 using systems will set untrusted, it cannot
                         * work.
                         */
                        if (WARN_ON(IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)))
                                return -1;
                        untrusted = gdev->dev;
                }
        }

        /*
         * If the common dma ops are not selected in kconfig then we cannot use
         * IOMMU_DOMAIN_DMA at all. Force IDENTITY if nothing else has been
         * selected.
         */
        if (!IS_ENABLED(CONFIG_IOMMU_DMA)) {
                if (WARN_ON(driver_type == IOMMU_DOMAIN_DMA))
                        return -1;
                if (!driver_type)
                        driver_type = IOMMU_DOMAIN_IDENTITY;
        }

        if (untrusted) {
                if (driver_type && driver_type != IOMMU_DOMAIN_DMA) {
                        dev_err_ratelimited(
                                untrusted,
                                "Device is not trusted, but driver is overriding group %u to %s, refusing to probe.\n",
                                group->id, iommu_domain_type_str(driver_type));
                        return -1;
                }
                driver_type = IOMMU_DOMAIN_DMA;
        }

        if (target_type) {
                if (driver_type && target_type != driver_type)
                        return -1;
                return target_type;
        }
        return driver_type;
}

static void iommu_group_do_probe_finalize(struct device *dev)
{
        const struct iommu_ops *ops = dev_iommu_ops(dev);

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

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

        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) {
                struct group_device *gdev;

                mutex_lock(&group->mutex);

                /* Remove item from the list */
                list_del_init(&group->entry);

                /*
                 * We go to the trouble of deferred default domain creation so
                 * that the cross-group default domain type and the setup of the
                 * IOMMU_RESV_DIRECT will work correctly in non-hotpug scenarios.
                 */
                ret = iommu_setup_default_domain(group, 0);
                if (ret) {
                        mutex_unlock(&group->mutex);
                        return ret;
                }
                for_each_group_device(group, gdev)
                        iommu_setup_dma_ops(gdev->dev, group->default_domain);
                mutex_unlock(&group->mutex);

                /*
                 * FIXME: Mis-locked because the ops->probe_finalize() call-back
                 * of some 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.
                 */
                for_each_group_device(group, gdev)
                        iommu_group_do_probe_finalize(gdev->dev);
        }

        return 0;
}

/**
 * device_iommu_capable() - check for a general IOMMU capability
 * @dev: device to which the capability would be relevant, if available
 * @cap: IOMMU capability
 *
 * Return: true if an IOMMU is present and supports the given capability
 * for the given device, otherwise false.
 */
bool device_iommu_capable(struct device *dev, enum iommu_cap cap)
{
        const struct iommu_ops *ops;

        if (!dev_has_iommu(dev))
                return false;

        ops = dev_iommu_ops(dev);
        if (!ops->capable)
                return false;

        return ops->capable(dev, cap);
}
EXPORT_SYMBOL_GPL(device_iommu_capable);

/**
 * iommu_group_has_isolated_msi() - Compute msi_device_has_isolated_msi()
 *       for a group
 * @group: Group to query
 *
 * IOMMU groups should not have differing values of
 * msi_device_has_isolated_msi() for devices in a group. However nothing
 * directly prevents this, so ensure mistakes don't result in isolation failures
 * by checking that all the devices are the same.
 */
bool iommu_group_has_isolated_msi(struct iommu_group *group)
{
        struct group_device *group_dev;
        bool ret = true;

        mutex_lock(&group->mutex);
        for_each_group_device(group, group_dev)
                ret &= msi_device_has_isolated_msi(group_dev->dev);
        mutex_unlock(&group->mutex);
        return ret;
}
EXPORT_SYMBOL_GPL(iommu_group_has_isolated_msi);

/**
 * 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)
{
        if (WARN_ON(!domain || domain->cookie_type != IOMMU_COOKIE_NONE))
                return;

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

static void iommu_domain_init(struct iommu_domain *domain, unsigned int type,
                              const struct iommu_ops *ops)
{
        domain->type = type;
        domain->owner = ops;
        if (!domain->ops)
                domain->ops = ops->default_domain_ops;
}

static struct iommu_domain *
__iommu_paging_domain_alloc_flags(struct device *dev, unsigned int type,
                                  unsigned int flags)
{
        const struct iommu_ops *ops;
        struct iommu_domain *domain;

        if (!dev_has_iommu(dev))
                return ERR_PTR(-ENODEV);

        ops = dev_iommu_ops(dev);

        if (ops->domain_alloc_paging && !flags)
                domain = ops->domain_alloc_paging(dev);
        else if (ops->domain_alloc_paging_flags)
                domain = ops->domain_alloc_paging_flags(dev, flags, NULL);
#if IS_ENABLED(CONFIG_FSL_PAMU)
        else if (ops->domain_alloc && !flags)
                domain = ops->domain_alloc(IOMMU_DOMAIN_UNMANAGED);
#endif
        else
                return ERR_PTR(-EOPNOTSUPP);

        if (IS_ERR(domain))
                return domain;
        if (!domain)
                return ERR_PTR(-ENOMEM);

        iommu_domain_init(domain, type, ops);
        return domain;
}

/**
 * iommu_paging_domain_alloc_flags() - Allocate a paging domain
 * @dev: device for which the domain is allocated
 * @flags: Bitmap of iommufd_hwpt_alloc_flags
 *
 * Allocate a paging domain which will be managed by a kernel driver. Return
 * allocated domain if successful, or an ERR pointer for failure.
 */
struct iommu_domain *iommu_paging_domain_alloc_flags(struct device *dev,
                                                     unsigned int flags)
{
        return __iommu_paging_domain_alloc_flags(dev,
                                         IOMMU_DOMAIN_UNMANAGED, flags);
}
EXPORT_SYMBOL_GPL(iommu_paging_domain_alloc_flags);

void iommu_domain_free(struct iommu_domain *domain)
{
        switch (domain->cookie_type) {
        case IOMMU_COOKIE_DMA_IOVA:
                iommu_put_dma_cookie(domain);
                break;
        case IOMMU_COOKIE_DMA_MSI:
                iommu_put_msi_cookie(domain);
                break;
        case IOMMU_COOKIE_SVA:
                mmdrop(domain->mm);
                break;
        default:
                break;
        }
        if (domain->ops->free)
                domain->ops->free(domain);
}
EXPORT_SYMBOL_GPL(iommu_domain_free);

/*
 * Put the group's domain back to the appropriate core-owned domain - either the
 * standard kernel-mode DMA configuration or an all-DMA-blocked domain.
 */
static void __iommu_group_set_core_domain(struct iommu_group *group)
{
        struct iommu_domain *new_domain;

        if (group->owner)
                new_domain = group->blocking_domain;
        else
                new_domain = group->default_domain;

        __iommu_group_set_domain_nofail(group, new_domain);
}

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

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

        ret = domain->ops->attach_dev(domain, dev, old);
        if (ret)
                return ret;
        dev->iommu->attach_deferred = 0;
        trace_attach_device_to_domain(dev);
        return 0;
}

/**
 * iommu_attach_device - Attach an IOMMU domain to a device
 * @domain: IOMMU domain to attach
 * @dev: Device that will be attached
 *
 * Returns 0 on success and error code on failure
 *
 * Note that EINVAL can be treated as a soft failure, indicating
 * that certain configuration of the domain is incompatible with
 * the device. In this case attaching a different domain to the
 * device may succeed.
 */
int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
{
        /* Caller must be a probed driver on dev */
        struct iommu_group *group = dev->iommu_group;
        int ret;

        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 (list_count_nodes(&group->devices) != 1)
                goto out_unlock;

        ret = __iommu_attach_group(domain, group);

out_unlock:
        mutex_unlock(&group->mutex);
        return ret;
}
EXPORT_SYMBOL_GPL(iommu_attach_device);

int iommu_deferred_attach(struct device *dev, struct iommu_domain *domain)
{
        /*
         * This is called on the dma mapping fast path so avoid locking. This is
         * racy, but we have an expectation that the driver will setup its DMAs
         * inside probe while being single threaded to avoid racing.
         */
        if (!dev->iommu || !dev->iommu->attach_deferred)
                return 0;

        guard(mutex)(&dev->iommu_group->mutex);

        /*
         * This is a concurrent attach during a device reset. Reject it until
         * pci_dev_reset_iommu_done() attaches the device to group->domain.
         *
         * Note that this might fail the iommu_dma_map(). But there's nothing
         * more we can do here.
         */
        if (dev->iommu_group->resetting_domain)
                return -EBUSY;
        return __iommu_attach_device(domain, dev, NULL);
}

void iommu_detach_device(struct iommu_domain *domain, struct device *dev)
{
        /* Caller must be a probed driver on dev */
        struct iommu_group *group = dev->iommu_group;

        if (!group)
                return;

        mutex_lock(&group->mutex);
        if (WARN_ON(domain != group->domain) ||
            WARN_ON(list_count_nodes(&group->devices) != 1))
                goto out_unlock;
        __iommu_group_set_core_domain(group);

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

/**
 * iommu_get_domain_for_dev() - Return the DMA API domain pointer
 * @dev: Device to query
 *
 * This function can be called within a driver bound to dev. The returned
 * pointer is valid for the lifetime of the bound driver.
 *
 * It should not be called by drivers with driver_managed_dma = true.
 */
struct iommu_domain *iommu_get_domain_for_dev(struct device *dev)
{
        /* Caller must be a probed driver on dev */
        struct iommu_group *group = dev->iommu_group;

        if (!group)
                return NULL;

        lockdep_assert_not_held(&group->mutex);

        return group->domain;
}
EXPORT_SYMBOL_GPL(iommu_get_domain_for_dev);

/**
 * iommu_driver_get_domain_for_dev() - Return the driver-level domain pointer
 * @dev: Device to query
 *
 * This function can be called by an iommu driver that wants to get the physical
 * domain within an iommu callback function where group->mutex is held.
 */
struct iommu_domain *iommu_driver_get_domain_for_dev(struct device *dev)
{
        struct iommu_group *group = dev->iommu_group;

        lockdep_assert_held(&group->mutex);

        /*
         * Driver handles the low-level __iommu_attach_device(), including the
         * one invoked by pci_dev_reset_iommu_done() re-attaching the device to
         * the cached group->domain. In this case, the driver must get the old
         * domain from group->resetting_domain rather than group->domain. This
         * prevents it from re-attaching the device from group->domain (old) to
         * group->domain (new).
         */
        if (group->resetting_domain)
                return group->resetting_domain;

        return group->domain;
}
EXPORT_SYMBOL_GPL(iommu_driver_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;
}

static void *iommu_make_pasid_array_entry(struct iommu_domain *domain,
                                          struct iommu_attach_handle *handle)
{
        if (handle) {
                handle->domain = domain;
                return xa_tag_pointer(handle, IOMMU_PASID_ARRAY_HANDLE);
        }

        return xa_tag_pointer(domain, IOMMU_PASID_ARRAY_DOMAIN);
}

static bool domain_iommu_ops_compatible(const struct iommu_ops *ops,
                                        struct iommu_domain *domain)
{
        if (domain->owner == ops)
                return true;

        /* For static domains, owner isn't set. */
        if (domain == ops->blocked_domain || domain == ops->identity_domain)
                return true;

        return false;
}

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

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

        dev = iommu_group_first_dev(group);
        if (!dev_has_iommu(dev) ||
            !domain_iommu_ops_compatible(dev_iommu_ops(dev), domain))
                return -EINVAL;

        return __iommu_group_set_domain(group, domain);
}

/**
 * iommu_attach_group - Attach an IOMMU domain to an IOMMU group
 * @domain: IOMMU domain to attach
 * @group: IOMMU group that will be attached
 *
 * Returns 0 on success and error code on failure
 *
 * Note that EINVAL can be treated as a soft failure, indicating
 * that certain configuration of the domain is incompatible with
 * the group. In this case attaching a different domain to the
 * group may succeed.
 */
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_device_set_domain(struct iommu_group *group,
                                     struct device *dev,
                                     struct iommu_domain *new_domain,
                                     struct iommu_domain *old_domain,
                                     unsigned int flags)
{
        int ret;

        /*
         * If the device requires IOMMU_RESV_DIRECT then we cannot allow
         * the blocking domain to be attached as it does not contain the
         * required 1:1 mapping. This test effectively excludes the device
         * being used with iommu_group_claim_dma_owner() which will block
         * vfio and iommufd as well.
         */
        if (dev->iommu->require_direct &&
            (new_domain->type == IOMMU_DOMAIN_BLOCKED ||
             new_domain == group->blocking_domain)) {
                dev_warn(dev,
                         "Firmware has requested this device have a 1:1 IOMMU mapping, rejecting configuring the device without a 1:1 mapping. Contact your platform vendor.\n");
                return -EINVAL;
        }

        if (dev->iommu->attach_deferred) {
                if (new_domain == group->default_domain)
                        return 0;
                dev->iommu->attach_deferred = 0;
        }

        ret = __iommu_attach_device(new_domain, dev, old_domain);
        if (ret) {
                /*
                 * If we have a blocking domain then try to attach that in hopes
                 * of avoiding a UAF. Modern drivers should implement blocking
                 * domains as global statics that cannot fail.
                 */
                if ((flags & IOMMU_SET_DOMAIN_MUST_SUCCEED) &&
                    group->blocking_domain &&
                    group->blocking_domain != new_domain)
                        __iommu_attach_device(group->blocking_domain, dev,
                                              old_domain);
                return ret;
        }
        return 0;
}

/*
 * If 0 is returned the group's domain is new_domain. If an error is returned
 * then the group's domain will be set back to the existing domain unless
 * IOMMU_SET_DOMAIN_MUST_SUCCEED, otherwise an error is returned and the group's
 * domains is left inconsistent. This is a driver bug to fail attach with a
 * previously good domain. We try to avoid a kernel UAF because of this.
 *
 * 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_set_domain_internal(struct iommu_group *group,
                                             struct iommu_domain *new_domain,
                                             unsigned int flags)
{
        struct group_device *last_gdev;
        struct group_device *gdev;
        int result;
        int ret;

        lockdep_assert_held(&group->mutex);

        if (group->domain == new_domain)
                return 0;

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

        /*
         * This is a concurrent attach during a device reset. Reject it until
         * pci_dev_reset_iommu_done() attaches the device to group->domain.
         */
        if (group->resetting_domain)
                return -EBUSY;

        /*
         * Changing the domain is done by calling attach_dev() on the new
         * domain. This switch does not have to be atomic and DMA can be
         * discarded during the transition. DMA must only be able to access
         * either new_domain or group->domain, never something else.
         */
        result = 0;
        for_each_group_device(group, gdev) {
                ret = __iommu_device_set_domain(group, gdev->dev, new_domain,
                                                group->domain, flags);
                if (ret) {
                        result = ret;
                        /*
                         * Keep trying the other devices in the group. If a
                         * driver fails attach to an otherwise good domain, and
                         * does not support blocking domains, it should at least
                         * drop its reference on the current domain so we don't
                         * UAF.
                         */
                        if (flags & IOMMU_SET_DOMAIN_MUST_SUCCEED)
                                continue;
                        goto err_revert;
                }
        }
        group->domain = new_domain;
        return result;

err_revert:
        /*
         * This is called in error unwind paths. A well behaved driver should
         * always allow us to attach to a domain that was already attached.
         */
        last_gdev = gdev;
        for_each_group_device(group, gdev) {
                /* No need to revert the last gdev that failed to set domain */
                if (gdev == last_gdev)
                        break;
                /*
                 * A NULL domain can happen only for first probe, in which case
                 * we leave group->domain as NULL and let release clean
                 * everything up.
                 */
                if (group->domain)
                        WARN_ON(__iommu_device_set_domain(
                                group, gdev->dev, group->domain, new_domain,
                                IOMMU_SET_DOMAIN_MUST_SUCCEED));
        }
        return ret;
}

void iommu_detach_group(struct iommu_domain *domain, struct iommu_group *group)
{
        mutex_lock(&group->mutex);
        __iommu_group_set_core_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;
        size_t offset_end;
        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 (!check_add_overflow(offset, pgsize_next, &offset_end) &&
            offset_end <= size)
                size = offset;

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

int iommu_map_nosync(struct iommu_domain *domain, unsigned long iova,
                phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
{
        const struct iommu_domain_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;

        might_sleep_if(gfpflags_allow_blocking(gfp));

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

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

        /* Discourage passing strange GFP flags */
        if (WARN_ON_ONCE(gfp & (__GFP_COMP | __GFP_DMA | __GFP_DMA32 |
                                __GFP_HIGHMEM)))
                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 pgsize, count, mapped = 0;

                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);
                ret = ops->map_pages(domain, iova, paddr, pgsize, count, 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);
                iommu_debug_map(domain, orig_paddr, orig_size);
        }

        return ret;
}

int iommu_sync_map(struct iommu_domain *domain, unsigned long iova, size_t size)
{
        const struct iommu_domain_ops *ops = domain->ops;

        if (!ops->iotlb_sync_map)
                return 0;
        return ops->iotlb_sync_map(domain, iova, size);
}

int iommu_map(struct iommu_domain *domain, unsigned long iova,
              phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
{
        int ret;

        ret = iommu_map_nosync(domain, iova, paddr, size, prot, gfp);
        if (ret)
                return ret;

        ret = iommu_sync_map(domain, iova, size);
        if (ret)
                iommu_unmap(domain, iova, size);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_map);

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

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

        if (WARN_ON(!ops->unmap_pages || domain->pgsize_bitmap == 0UL))
                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);

        iommu_debug_unmap_begin(domain, iova, size);

        /*
         * Keep iterating until we either unmap 'size' bytes (or more)
         * or we hit an area that isn't mapped.
         */
        while (unmapped < size) {
                size_t pgsize, count;

                pgsize = iommu_pgsize(domain, iova, iova, size - unmapped, &count);
                unmapped_page = ops->unmap_pages(domain, iova, pgsize, count, 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);
        iommu_debug_unmap_end(domain, orig_iova, size, unmapped);
        return unmapped;
}

/**
 * iommu_unmap() - Remove mappings from a range of IOVA
 * @domain: Domain to manipulate
 * @iova: IO virtual address to start
 * @size: Length of the range starting from @iova
 *
 * iommu_unmap() will remove a translation created by iommu_map(). It cannot
 * subdivide a mapping created by iommu_map(), so it should be called with IOVA
 * ranges that match what was passed to iommu_map(). The range can aggregate
 * contiguous iommu_map() calls so long as no individual range is split.
 *
 * Returns: Number of bytes of IOVA unmapped. iova + res will be the point
 * unmapping stopped.
 */
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);

/**
 * iommu_unmap_fast() - Remove mappings from a range of IOVA without IOTLB sync
 * @domain: Domain to manipulate
 * @iova: IO virtual address to start
 * @size: Length of the range starting from @iova
 * @iotlb_gather: range information for a pending IOTLB flush
 *
 * iommu_unmap_fast() will remove a translation created by iommu_map().
 * It can't subdivide a mapping created by iommu_map(), so it should be
 * called with IOVA ranges that match what was passed to iommu_map(). The
 * range can aggregate contiguous iommu_map() calls so long as no individual
 * range is split.
 *
 * Basically iommu_unmap_fast() is the same as iommu_unmap() but for callers
 * which manage the IOTLB flushing externally to perform a batched sync.
 *
 * Returns: Number of bytes of IOVA unmapped. iova + res will be the point
 * unmapping stopped.
 */
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);

ssize_t iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
                     struct scatterlist *sg, unsigned int nents, int prot,
                     gfp_t gfp)
{
        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_nosync(domain, iova + mapped, start,
                                        len, prot, gfp);
                        if (ret)
                                goto out_err;

                        mapped += len;
                        len = 0;
                }

                if (sg_dma_is_bus_address(sg))
                        goto next;

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

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

        ret = iommu_sync_map(domain, iova, mapped);
        if (ret)
                goto out_err;

        return mapped;

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

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_map_sg);

/**
 * 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->cookie_type == IOMMU_COOKIE_FAULT_HANDLER &&
            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_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);

/**
 * iommu_get_resv_regions - get reserved regions
 * @dev: device for which to get reserved regions
 * @list: reserved region list for device
 *
 * This returns a list of reserved IOVA regions specific to this device.
 * A domain user should not map IOVA in these ranges.
 */
void iommu_get_resv_regions(struct device *dev, struct list_head *list)
{
        const struct iommu_ops *ops = dev_iommu_ops(dev);

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

/**
 * iommu_put_resv_regions - release reserved regions
 * @dev: device for which to free reserved regions
 * @list: reserved region list for device
 *
 * This releases a reserved region list acquired by iommu_get_resv_regions().
 */
void 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) {
                if (entry->free)
                        entry->free(dev, entry);
                else
                        kfree(entry);
        }
}
EXPORT_SYMBOL(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,
                                                  gfp_t gfp)
{
        struct iommu_resv_region *region;

        region = kzalloc_obj(*region, gfp);
        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);

static const struct iommu_device *iommu_from_fwnode(const struct fwnode_handle *fwnode)
{
        const struct iommu_device *iommu, *ret = NULL;

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

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

        return iommu ? iommu->ops : NULL;
}

int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode)
{
        const struct iommu_device *iommu = iommu_from_fwnode(iommu_fwnode);
        struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);

        if (!iommu)
                return driver_deferred_probe_check_state(dev);
        if (!dev->iommu && !READ_ONCE(iommu->ready))
                return -EPROBE_DEFER;

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

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

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

        fwnode_handle_get(iommu_fwnode);
        fwspec->iommu_fwnode = iommu_fwnode;
        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);
        }
}

int iommu_fwspec_add_ids(struct device *dev, const 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);

/**
 * iommu_setup_default_domain - Set the default_domain for the group
 * @group: Group to change
 * @target_type: Domain type to set as the default_domain
 *
 * Allocate a default domain and set it as the current domain on the group. If
 * the group already has a default domain it will be changed to the target_type.
 * When target_type is 0 the default domain is selected based on driver and
 * system preferences.
 */
static int iommu_setup_default_domain(struct iommu_group *group,
                                      int target_type)
{
        struct iommu_domain *old_dom = group->default_domain;
        struct group_device *gdev;
        struct iommu_domain *dom;
        bool direct_failed;
        int req_type;
        int ret;

        lockdep_assert_held(&group->mutex);

        req_type = iommu_get_default_domain_type(group, target_type);
        if (req_type < 0)
                return -EINVAL;

        dom = iommu_group_alloc_default_domain(group, req_type);
        if (IS_ERR(dom))
                return PTR_ERR(dom);

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

        if (iommu_is_dma_domain(dom)) {
                ret = iommu_get_dma_cookie(dom);
                if (ret) {
                        iommu_domain_free(dom);
                        return ret;
                }
        }

        /*
         * IOMMU_RESV_DIRECT and IOMMU_RESV_DIRECT_RELAXABLE regions must be
         * mapped before their device is attached, in order to guarantee
         * continuity with any FW activity
         */
        direct_failed = false;
        for_each_group_device(group, gdev) {
                if (iommu_create_device_direct_mappings(dom, gdev->dev)) {
                        direct_failed = true;
                        dev_warn_once(
                                gdev->dev->iommu->iommu_dev->dev,
                                "IOMMU driver was not able to establish FW requested direct mapping.");
                }
        }

        /* We must set default_domain early for __iommu_device_set_domain */
        group->default_domain = dom;
        if (!group->domain) {
                /*
                 * Drivers are not allowed to fail the first domain attach.
                 * The only way to recover from this is to fail attaching the
                 * iommu driver and call ops->release_device. Put the domain
                 * in group->default_domain so it is freed after.
                 */
                ret = __iommu_group_set_domain_internal(
                        group, dom, IOMMU_SET_DOMAIN_MUST_SUCCEED);
                if (WARN_ON(ret))
                        goto out_free_old;
        } else {
                ret = __iommu_group_set_domain(group, dom);
                if (ret)
                        goto err_restore_def_domain;
        }

        /*
         * Drivers are supposed to allow mappings to be installed in a domain
         * before device attachment, but some don't. Hack around this defect by
         * trying again after attaching. If this happens it means the device
         * will not continuously have the IOMMU_RESV_DIRECT map.
         */
        if (direct_failed) {
                for_each_group_device(group, gdev) {
                        ret = iommu_create_device_direct_mappings(dom, gdev->dev);
                        if (ret)
                                goto err_restore_domain;
                }
        }

out_free_old:
        if (old_dom)
                iommu_domain_free(old_dom);
        return ret;

err_restore_domain:
        if (old_dom)
                __iommu_group_set_domain_internal(
                        group, old_dom, IOMMU_SET_DOMAIN_MUST_SUCCEED);
err_restore_def_domain:
        if (old_dom) {
                iommu_domain_free(dom);
                group->default_domain = old_dom;
        }
        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.
 * group->mutex 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 *gdev;
        int ret, req_type;

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

        if (WARN_ON(!group) || !group->default_domain)
                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;

        mutex_lock(&group->mutex);
        /* We can bring up a flush queue without tearing down the domain. */
        if (req_type == IOMMU_DOMAIN_DMA_FQ &&
            group->default_domain->type == IOMMU_DOMAIN_DMA) {
                ret = iommu_dma_init_fq(group->default_domain);
                if (ret)
                        goto out_unlock;

                group->default_domain->type = IOMMU_DOMAIN_DMA_FQ;
                ret = count;
                goto out_unlock;
        }

        /* Otherwise, ensure that device exists and no driver is bound. */
        if (list_empty(&group->devices) || group->owner_cnt) {
                ret = -EPERM;
                goto out_unlock;
        }

        ret = iommu_setup_default_domain(group, req_type);
        if (ret)
                goto out_unlock;

        /* Make sure dma_ops is appropriatley set */
        for_each_group_device(group, gdev)
                iommu_setup_dma_ops(gdev->dev, group->default_domain);

out_unlock:
        mutex_unlock(&group->mutex);
        return ret ?: count;
}

/**
 * iommu_device_use_default_domain() - Device driver wants to handle device
 *                                     DMA through the kernel DMA API.
 * @dev: The device.
 *
 * The device driver about to bind @dev wants to do DMA through the kernel
 * DMA API. Return 0 if it is allowed, otherwise an error.
 */
int iommu_device_use_default_domain(struct device *dev)
{
        /* Caller is the driver core during the pre-probe path */
        struct iommu_group *group = dev->iommu_group;
        int ret = 0;

        if (!group)
                return 0;

        mutex_lock(&group->mutex);
        /* We may race against bus_iommu_probe() finalising groups here */
        if (!group->default_domain) {
                ret = -EPROBE_DEFER;
                goto unlock_out;
        }
        if (group->owner_cnt) {
                if (group->domain != group->default_domain || group->owner ||
                    !xa_empty(&group->pasid_array)) {
                        ret = -EBUSY;
                        goto unlock_out;
                }
        }

        group->owner_cnt++;

unlock_out:
        mutex_unlock(&group->mutex);
        return ret;
}

/**
 * iommu_device_unuse_default_domain() - Device driver stops handling device
 *                                       DMA through the kernel DMA API.
 * @dev: The device.
 *
 * The device driver doesn't want to do DMA through kernel DMA API anymore.
 * It must be called after iommu_device_use_default_domain().
 */
void iommu_device_unuse_default_domain(struct device *dev)
{
        /* Caller is the driver core during the post-probe path */
        struct iommu_group *group = dev->iommu_group;

        if (!group)
                return;

        mutex_lock(&group->mutex);
        if (!WARN_ON(!group->owner_cnt || !xa_empty(&group->pasid_array)))
                group->owner_cnt--;

        mutex_unlock(&group->mutex);
}

static int __iommu_group_alloc_blocking_domain(struct iommu_group *group)
{
        struct device *dev = iommu_group_first_dev(group);
        const struct iommu_ops *ops = dev_iommu_ops(dev);
        struct iommu_domain *domain;

        if (group->blocking_domain)
                return 0;

        if (ops->blocked_domain) {
                group->blocking_domain = ops->blocked_domain;
                return 0;
        }

        /*
         * For drivers that do not yet understand IOMMU_DOMAIN_BLOCKED create an
         * empty PAGING domain instead.
         */
        domain = iommu_paging_domain_alloc(dev);
        if (IS_ERR(domain))
                return PTR_ERR(domain);
        group->blocking_domain = domain;
        return 0;
}

static int __iommu_take_dma_ownership(struct iommu_group *group, void *owner)
{
        int ret;

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

        ret = __iommu_group_alloc_blocking_domain(group);
        if (ret)
                return ret;
        ret = __iommu_group_set_domain(group, group->blocking_domain);
        if (ret)
                return ret;

        group->owner = owner;
        group->owner_cnt++;
        return 0;
}

/**
 * iommu_group_claim_dma_owner() - Set DMA ownership of a group
 * @group: The group.
 * @owner: Caller specified pointer. Used for exclusive ownership.
 *
 * This is to support backward compatibility for vfio which manages the dma
 * ownership in iommu_group level. New invocations on this interface should be
 * prohibited. Only a single owner may exist for a group.
 */
int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner)
{
        int ret = 0;

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

        mutex_lock(&group->mutex);
        if (group->owner_cnt) {
                ret = -EPERM;
                goto unlock_out;
        }

        ret = __iommu_take_dma_ownership(group, owner);
unlock_out:
        mutex_unlock(&group->mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_group_claim_dma_owner);

/**
 * iommu_device_claim_dma_owner() - Set DMA ownership of a device
 * @dev: The device.
 * @owner: Caller specified pointer. Used for exclusive ownership.
 *
 * Claim the DMA ownership of a device. Multiple devices in the same group may
 * concurrently claim ownership if they present the same owner value. Returns 0
 * on success and error code on failure
 */
int iommu_device_claim_dma_owner(struct device *dev, void *owner)
{
        /* Caller must be a probed driver on dev */
        struct iommu_group *group = dev->iommu_group;
        int ret = 0;

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

        if (!group)
                return -ENODEV;

        mutex_lock(&group->mutex);
        if (group->owner_cnt) {
                if (group->owner != owner) {
                        ret = -EPERM;
                        goto unlock_out;
                }
                group->owner_cnt++;
                goto unlock_out;
        }

        ret = __iommu_take_dma_ownership(group, owner);
unlock_out:
        mutex_unlock(&group->mutex);
        return ret;
}
EXPORT_SYMBOL_GPL(iommu_device_claim_dma_owner);

static void __iommu_release_dma_ownership(struct iommu_group *group)
{
        if (WARN_ON(!group->owner_cnt || !group->owner ||
                    !xa_empty(&group->pasid_array)))
                return;

        group->owner_cnt = 0;
        group->owner = NULL;
        __iommu_group_set_domain_nofail(group, group->default_domain);
}

/**
 * iommu_group_release_dma_owner() - Release DMA ownership of a group
 * @group: The group
 *
 * Release the DMA ownership claimed by iommu_group_claim_dma_owner().
 */
void iommu_group_release_dma_owner(struct iommu_group *group)
{
        mutex_lock(&group->mutex);
        __iommu_release_dma_ownership(group);
        mutex_unlock(&group->mutex);
}
EXPORT_SYMBOL_GPL(iommu_group_release_dma_owner);

/**
 * iommu_device_release_dma_owner() - Release DMA ownership of a device
 * @dev: The device.
 *
 * Release the DMA ownership claimed by iommu_device_claim_dma_owner().
 */
void iommu_device_release_dma_owner(struct device *dev)
{
        /* Caller must be a probed driver on dev */
        struct iommu_group *group = dev->iommu_group;

        mutex_lock(&group->mutex);
        if (group->owner_cnt > 1)
                group->owner_cnt--;
        else
                __iommu_release_dma_ownership(group);
        mutex_unlock(&group->mutex);
}
EXPORT_SYMBOL_GPL(iommu_device_release_dma_owner);

/**
 * iommu_group_dma_owner_claimed() - Query group dma ownership status
 * @group: The group.
 *
 * This provides status query on a given group. It is racy and only for
 * non-binding status reporting.
 */
bool iommu_group_dma_owner_claimed(struct iommu_group *group)
{
        unsigned int user;

        mutex_lock(&group->mutex);
        user = group->owner_cnt;
        mutex_unlock(&group->mutex);

        return user;
}
EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed);

static void iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid,
                                   struct iommu_domain *domain)
{
        const struct iommu_ops *ops = dev_iommu_ops(dev);
        struct iommu_domain *blocked_domain = ops->blocked_domain;

        WARN_ON(blocked_domain->ops->set_dev_pasid(blocked_domain,
                                                   dev, pasid, domain));
}

static int __iommu_set_group_pasid(struct iommu_domain *domain,
                                   struct iommu_group *group, ioasid_t pasid,
                                   struct iommu_domain *old)
{
        struct group_device *device, *last_gdev;
        int ret;

        for_each_group_device(group, device) {
                if (device->dev->iommu->max_pasids > 0) {
                        ret = domain->ops->set_dev_pasid(domain, device->dev,
                                                         pasid, old);
                        if (ret)
                                goto err_revert;
                }
        }

        return 0;

err_revert:
        last_gdev = device;
        for_each_group_device(group, device) {
                if (device == last_gdev)
                        break;
                if (device->dev->iommu->max_pasids > 0) {
                        /*
                         * If no old domain, undo the succeeded devices/pasid.
                         * Otherwise, rollback the succeeded devices/pasid to
                         * the old domain. And it is a driver bug to fail
                         * attaching with a previously good domain.
                         */
                        if (!old ||
                            WARN_ON(old->ops->set_dev_pasid(old, device->dev,
                                                            pasid, domain)))
                                iommu_remove_dev_pasid(device->dev, pasid, domain);
                }
        }
        return ret;
}

static void __iommu_remove_group_pasid(struct iommu_group *group,
                                       ioasid_t pasid,
                                       struct iommu_domain *domain)
{
        struct group_device *device;

        for_each_group_device(group, device) {
                if (device->dev->iommu->max_pasids > 0)
                        iommu_remove_dev_pasid(device->dev, pasid, domain);
        }
}

/*
 * iommu_attach_device_pasid() - Attach a domain to pasid of device
 * @domain: the iommu domain.
 * @dev: the attached device.
 * @pasid: the pasid of the device.
 * @handle: the attach handle.
 *
 * Caller should always provide a new handle to avoid race with the paths
 * that have lockless reference to handle if it intends to pass a valid handle.
 *
 * Return: 0 on success, or an error.
 */
int iommu_attach_device_pasid(struct iommu_domain *domain,
                              struct device *dev, ioasid_t pasid,
                              struct iommu_attach_handle *handle)
{
        /* Caller must be a probed driver on dev */
        struct iommu_group *group = dev->iommu_group;
        struct group_device *device;
        const struct iommu_ops *ops;
        void *entry;
        int ret;

        if (!group)
                return -ENODEV;

        ops = dev_iommu_ops(dev);

        if (!domain->ops->set_dev_pasid ||
            !ops->blocked_domain ||
            !ops->blocked_domain->ops->set_dev_pasid)
                return -EOPNOTSUPP;

        if (!domain_iommu_ops_compatible(ops, domain) ||
            pasid == IOMMU_NO_PASID)
                return -EINVAL;

        mutex_lock(&group->mutex);

        /*
         * This is a concurrent attach during a device reset. Reject it until
         * pci_dev_reset_iommu_done() attaches the device to group->domain.
         */
        if (group->resetting_domain) {
                ret = -EBUSY;
                goto out_unlock;
        }

        for_each_group_device(group, device) {
                /*
                 * Skip PASID validation for devices without PASID support
                 * (max_pasids = 0). These devices cannot issue transactions
                 * with PASID, so they don't affect group's PASID usage.
                 */
                if ((device->dev->iommu->max_pasids > 0) &&
                    (pasid >= device->dev->iommu->max_pasids)) {
                        ret = -EINVAL;
                        goto out_unlock;
                }
        }

        entry = iommu_make_pasid_array_entry(domain, handle);

        /*
         * Entry present is a failure case. Use xa_insert() instead of
         * xa_reserve().
         */
        ret = xa_insert(&group->pasid_array, pasid, XA_ZERO_ENTRY, GFP_KERNEL);
        if (ret)
                goto out_unlock;

        ret = __iommu_set_group_pasid(domain, group, pasid, NULL);
        if (ret) {
                xa_release(&group->pasid_array, pasid);
                goto out_unlock;
        }

        /*
         * The xa_insert() above reserved the memory, and the group->mutex is
         * held, this cannot fail. The new domain cannot be visible until the
         * operation succeeds as we cannot tolerate PRIs becoming concurrently
         * queued and then failing attach.
         */
        WARN_ON(xa_is_err(xa_store(&group->pasid_array,
                                   pasid, entry, GFP_KERNEL)));

out_unlock:
        mutex_unlock(&group->mutex);
        return ret;
}
EXPORT_SYMBOL_GPL(iommu_attach_device_pasid);

/**
 * iommu_replace_device_pasid - Replace the domain that a specific pasid
 *                              of the device is attached to
 * @domain: the new iommu domain
 * @dev: the attached device.
 * @pasid: the pasid of the device.
 * @handle: the attach handle.
 *
 * This API allows the pasid to switch domains. The @pasid should have been
 * attached. Otherwise, this fails. The pasid will keep the old configuration
 * if replacement failed.
 *
 * Caller should always provide a new handle to avoid race with the paths
 * that have lockless reference to handle if it intends to pass a valid handle.
 *
 * Return 0 on success, or an error.
 */
int iommu_replace_device_pasid(struct iommu_domain *domain,
                               struct device *dev, ioasid_t pasid,
                               struct iommu_attach_handle *handle)
{
        /* Caller must be a probed driver on dev */
        struct iommu_group *group = dev->iommu_group;
        struct iommu_attach_handle *entry;
        struct iommu_domain *curr_domain;
        void *curr;
        int ret;

        if (!group)
                return -ENODEV;

        if (!domain->ops->set_dev_pasid)
                return -EOPNOTSUPP;

        if (!domain_iommu_ops_compatible(dev_iommu_ops(dev), domain) ||
            pasid == IOMMU_NO_PASID || !handle)
                return -EINVAL;

        mutex_lock(&group->mutex);

        /*
         * This is a concurrent attach during a device reset. Reject it until
         * pci_dev_reset_iommu_done() attaches the device to group->domain.
         */
        if (group->resetting_domain) {
                ret = -EBUSY;
                goto out_unlock;
        }

        entry = iommu_make_pasid_array_entry(domain, handle);
        curr = xa_cmpxchg(&group->pasid_array, pasid, NULL,
                          XA_ZERO_ENTRY, GFP_KERNEL);
        if (xa_is_err(curr)) {
                ret = xa_err(curr);
                goto out_unlock;
        }

        /*
         * No domain (with or without handle) attached, hence not
         * a replace case.
         */
        if (!curr) {
                xa_release(&group->pasid_array, pasid);
                ret = -EINVAL;
                goto out_unlock;
        }

        /*
         * Reusing handle is problematic as there are paths that refers
         * the handle without lock. To avoid race, reject the callers that
         * attempt it.
         */
        if (curr == entry) {
                WARN_ON(1);
                ret = -EINVAL;
                goto out_unlock;
        }

        curr_domain = pasid_array_entry_to_domain(curr);
        ret = 0;

        if (curr_domain != domain) {
                ret = __iommu_set_group_pasid(domain, group,
                                              pasid, curr_domain);
                if (ret)
                        goto out_unlock;
        }

        /*
         * The above xa_cmpxchg() reserved the memory, and the
         * group->mutex is held, this cannot fail.
         */
        WARN_ON(xa_is_err(xa_store(&group->pasid_array,
                                   pasid, entry, GFP_KERNEL)));

out_unlock:
        mutex_unlock(&group->mutex);
        return ret;
}
EXPORT_SYMBOL_NS_GPL(iommu_replace_device_pasid, "IOMMUFD_INTERNAL");

/*
 * iommu_detach_device_pasid() - Detach the domain from pasid of device
 * @domain: the iommu domain.
 * @dev: the attached device.
 * @pasid: the pasid of the device.
 *
 * The @domain must have been attached to @pasid of the @dev with
 * iommu_attach_device_pasid().
 */
void iommu_detach_device_pasid(struct iommu_domain *domain, struct device *dev,
                               ioasid_t pasid)
{
        /* Caller must be a probed driver on dev */
        struct iommu_group *group = dev->iommu_group;

        mutex_lock(&group->mutex);
        __iommu_remove_group_pasid(group, pasid, domain);
        xa_erase(&group->pasid_array, pasid);
        mutex_unlock(&group->mutex);
}
EXPORT_SYMBOL_GPL(iommu_detach_device_pasid);

ioasid_t iommu_alloc_global_pasid(struct device *dev)
{
        int ret;

        /* max_pasids == 0 means that the device does not support PASID */
        if (!dev->iommu->max_pasids)
                return IOMMU_PASID_INVALID;

        /*
         * max_pasids is set up by vendor driver based on number of PASID bits
         * supported but the IDA allocation is inclusive.
         */
        ret = ida_alloc_range(&iommu_global_pasid_ida, IOMMU_FIRST_GLOBAL_PASID,
                              dev->iommu->max_pasids - 1, GFP_KERNEL);
        return ret < 0 ? IOMMU_PASID_INVALID : ret;
}
EXPORT_SYMBOL_GPL(iommu_alloc_global_pasid);

void iommu_free_global_pasid(ioasid_t pasid)
{
        if (WARN_ON(pasid == IOMMU_PASID_INVALID))
                return;

        ida_free(&iommu_global_pasid_ida, pasid);
}
EXPORT_SYMBOL_GPL(iommu_free_global_pasid);

/**
 * iommu_attach_handle_get - Return the attach handle
 * @group: the iommu group that domain was attached to
 * @pasid: the pasid within the group
 * @type: matched domain type, 0 for any match
 *
 * Return handle or ERR_PTR(-ENOENT) on none, ERR_PTR(-EBUSY) on mismatch.
 *
 * Return the attach handle to the caller. The life cycle of an iommu attach
 * handle is from the time when the domain is attached to the time when the
 * domain is detached. Callers are required to synchronize the call of
 * iommu_attach_handle_get() with domain attachment and detachment. The attach
 * handle can only be used during its life cycle.
 */
struct iommu_attach_handle *
iommu_attach_handle_get(struct iommu_group *group, ioasid_t pasid, unsigned int type)
{
        struct iommu_attach_handle *handle;
        void *entry;

        xa_lock(&group->pasid_array);
        entry = xa_load(&group->pasid_array, pasid);
        if (!entry || xa_pointer_tag(entry) != IOMMU_PASID_ARRAY_HANDLE) {
                handle = ERR_PTR(-ENOENT);
        } else {
                handle = xa_untag_pointer(entry);
                if (type && handle->domain->type != type)
                        handle = ERR_PTR(-EBUSY);
        }
        xa_unlock(&group->pasid_array);

        return handle;
}
EXPORT_SYMBOL_NS_GPL(iommu_attach_handle_get, "IOMMUFD_INTERNAL");

/**
 * iommu_attach_group_handle - Attach an IOMMU domain to an IOMMU group
 * @domain: IOMMU domain to attach
 * @group: IOMMU group that will be attached
 * @handle: attach handle
 *
 * Returns 0 on success and error code on failure.
 *
 * This is a variant of iommu_attach_group(). It allows the caller to provide
 * an attach handle and use it when the domain is attached. This is currently
 * used by IOMMUFD to deliver the I/O page faults.
 *
 * Caller should always provide a new handle to avoid race with the paths
 * that have lockless reference to handle.
 */
int iommu_attach_group_handle(struct iommu_domain *domain,
                              struct iommu_group *group,
                              struct iommu_attach_handle *handle)
{
        void *entry;
        int ret;

        if (!handle)
                return -EINVAL;

        mutex_lock(&group->mutex);
        entry = iommu_make_pasid_array_entry(domain, handle);
        ret = xa_insert(&group->pasid_array,
                        IOMMU_NO_PASID, XA_ZERO_ENTRY, GFP_KERNEL);
        if (ret)
                goto out_unlock;

        ret = __iommu_attach_group(domain, group);
        if (ret) {
                xa_release(&group->pasid_array, IOMMU_NO_PASID);
                goto out_unlock;
        }

        /*
         * The xa_insert() above reserved the memory, and the group->mutex is
         * held, this cannot fail. The new domain cannot be visible until the
         * operation succeeds as we cannot tolerate PRIs becoming concurrently
         * queued and then failing attach.
         */
        WARN_ON(xa_is_err(xa_store(&group->pasid_array,
                                   IOMMU_NO_PASID, entry, GFP_KERNEL)));

out_unlock:
        mutex_unlock(&group->mutex);
        return ret;
}
EXPORT_SYMBOL_NS_GPL(iommu_attach_group_handle, "IOMMUFD_INTERNAL");

/**
 * iommu_detach_group_handle - Detach an IOMMU domain from an IOMMU group
 * @domain: IOMMU domain to attach
 * @group: IOMMU group that will be attached
 *
 * Detach the specified IOMMU domain from the specified IOMMU group.
 * It must be used in conjunction with iommu_attach_group_handle().
 */
void iommu_detach_group_handle(struct iommu_domain *domain,
                               struct iommu_group *group)
{
        mutex_lock(&group->mutex);
        __iommu_group_set_core_domain(group);
        xa_erase(&group->pasid_array, IOMMU_NO_PASID);
        mutex_unlock(&group->mutex);
}
EXPORT_SYMBOL_NS_GPL(iommu_detach_group_handle, "IOMMUFD_INTERNAL");

/**
 * iommu_replace_group_handle - replace the domain that a group is attached to
 * @group: IOMMU group that will be attached to the new domain
 * @new_domain: new IOMMU domain to replace with
 * @handle: attach handle
 *
 * This API allows the group to switch domains without being forced to go to
 * the blocking domain in-between. It allows the caller to provide an attach
 * handle for the new domain and use it when the domain is attached.
 *
 * If the currently attached domain is a core domain (e.g. a default_domain),
 * it will act just like the iommu_attach_group_handle().
 *
 * Caller should always provide a new handle to avoid race with the paths
 * that have lockless reference to handle.
 */
int iommu_replace_group_handle(struct iommu_group *group,
                               struct iommu_domain *new_domain,
                               struct iommu_attach_handle *handle)
{
        void *curr, *entry;
        int ret;

        if (!new_domain || !handle)
                return -EINVAL;

        mutex_lock(&group->mutex);
        entry = iommu_make_pasid_array_entry(new_domain, handle);
        ret = xa_reserve(&group->pasid_array, IOMMU_NO_PASID, GFP_KERNEL);
        if (ret)
                goto err_unlock;

        ret = __iommu_group_set_domain(group, new_domain);
        if (ret)
                goto err_release;

        curr = xa_store(&group->pasid_array, IOMMU_NO_PASID, entry, GFP_KERNEL);
        WARN_ON(xa_is_err(curr));

        mutex_unlock(&group->mutex);

        return 0;
err_release:
        xa_release(&group->pasid_array, IOMMU_NO_PASID);
err_unlock:
        mutex_unlock(&group->mutex);
        return ret;
}
EXPORT_SYMBOL_NS_GPL(iommu_replace_group_handle, "IOMMUFD_INTERNAL");

/**
 * pci_dev_reset_iommu_prepare() - Block IOMMU to prepare for a PCI device reset
 * @pdev: PCI device that is going to enter a reset routine
 *
 * The PCIe r6.0, sec 10.3.1 IMPLEMENTATION NOTE recommends to disable and block
 * ATS before initiating a reset. This means that a PCIe device during the reset
 * routine wants to block any IOMMU activity: translation and ATS invalidation.
 *
 * This function attaches the device's RID/PASID(s) the group->blocking_domain,
 * setting the group->resetting_domain. This allows the IOMMU driver pausing any
 * IOMMU activity while leaving the group->domain pointer intact. Later when the
 * reset is finished, pci_dev_reset_iommu_done() can restore everything.
 *
 * Caller must use pci_dev_reset_iommu_prepare() with pci_dev_reset_iommu_done()
 * before/after the core-level reset routine, to unset the resetting_domain.
 *
 * Return: 0 on success or negative error code if the preparation failed.
 *
 * These two functions are designed to be used by PCI reset functions that would
 * not invoke any racy iommu_release_device(), since PCI sysfs node gets removed
 * before it notifies with a BUS_NOTIFY_REMOVED_DEVICE. When using them in other
 * case, callers must ensure there will be no racy iommu_release_device() call,
 * which otherwise would UAF the dev->iommu_group pointer.
 */
int pci_dev_reset_iommu_prepare(struct pci_dev *pdev)
{
        struct iommu_group *group = pdev->dev.iommu_group;
        unsigned long pasid;
        void *entry;
        int ret;

        if (!pci_ats_supported(pdev) || !dev_has_iommu(&pdev->dev))
                return 0;

        guard(mutex)(&group->mutex);

        /* Re-entry is not allowed */
        if (WARN_ON(group->resetting_domain))
                return -EBUSY;

        ret = __iommu_group_alloc_blocking_domain(group);
        if (ret)
                return ret;

        /* Stage RID domain at blocking_domain while retaining group->domain */
        if (group->domain != group->blocking_domain) {
                ret = __iommu_attach_device(group->blocking_domain, &pdev->dev,
                                            group->domain);
                if (ret)
                        return ret;
        }

        /*
         * Stage PASID domains at blocking_domain while retaining pasid_array.
         *
         * The pasid_array is mostly fenced by group->mutex, except one reader
         * in iommu_attach_handle_get(), so it's safe to read without xa_lock.
         */
        xa_for_each_start(&group->pasid_array, pasid, entry, 1)
                iommu_remove_dev_pasid(&pdev->dev, pasid,
                                       pasid_array_entry_to_domain(entry));

        group->resetting_domain = group->blocking_domain;
        return ret;
}
EXPORT_SYMBOL_GPL(pci_dev_reset_iommu_prepare);

/**
 * pci_dev_reset_iommu_done() - Restore IOMMU after a PCI device reset is done
 * @pdev: PCI device that has finished a reset routine
 *
 * After a PCIe device finishes a reset routine, it wants to restore its IOMMU
 * IOMMU activity, including new translation as well as cache invalidation, by
 * re-attaching all RID/PASID of the device's back to the domains retained in
 * the core-level structure.
 *
 * Caller must pair it with a successful pci_dev_reset_iommu_prepare().
 *
 * Note that, although unlikely, there is a risk that re-attaching domains might
 * fail due to some unexpected happening like OOM.
 */
void pci_dev_reset_iommu_done(struct pci_dev *pdev)
{
        struct iommu_group *group = pdev->dev.iommu_group;
        unsigned long pasid;
        void *entry;

        if (!pci_ats_supported(pdev) || !dev_has_iommu(&pdev->dev))
                return;

        guard(mutex)(&group->mutex);

        /* pci_dev_reset_iommu_prepare() was bypassed for the device */
        if (!group->resetting_domain)
                return;

        /* pci_dev_reset_iommu_prepare() was not successfully called */
        if (WARN_ON(!group->blocking_domain))
                return;

        /* Re-attach RID domain back to group->domain */
        if (group->domain != group->blocking_domain) {
                WARN_ON(__iommu_attach_device(group->domain, &pdev->dev,
                                              group->blocking_domain));
        }

        /*
         * Re-attach PASID domains back to the domains retained in pasid_array.
         *
         * The pasid_array is mostly fenced by group->mutex, except one reader
         * in iommu_attach_handle_get(), so it's safe to read without xa_lock.
         */
        xa_for_each_start(&group->pasid_array, pasid, entry, 1)
                WARN_ON(__iommu_set_group_pasid(
                        pasid_array_entry_to_domain(entry), group, pasid,
                        group->blocking_domain));

        group->resetting_domain = NULL;
}
EXPORT_SYMBOL_GPL(pci_dev_reset_iommu_done);

#if IS_ENABLED(CONFIG_IRQ_MSI_IOMMU)
/**
 * iommu_dma_prepare_msi() - Map the MSI page in the IOMMU domain
 * @desc: MSI descriptor, will store the MSI page
 * @msi_addr: MSI target address to be mapped
 *
 * The implementation of sw_msi() should take msi_addr and map it to
 * an IOVA in the domain and call msi_desc_set_iommu_msi_iova() with the
 * mapping information.
 *
 * Return: 0 on success or negative error code if the mapping failed.
 */
int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
{
        struct device *dev = msi_desc_to_dev(desc);
        struct iommu_group *group = dev->iommu_group;
        int ret = 0;

        if (!group)
                return 0;

        mutex_lock(&group->mutex);
        /* An IDENTITY domain must pass through */
        if (group->domain && group->domain->type != IOMMU_DOMAIN_IDENTITY) {
                switch (group->domain->cookie_type) {
                case IOMMU_COOKIE_DMA_MSI:
                case IOMMU_COOKIE_DMA_IOVA:
                        ret = iommu_dma_sw_msi(group->domain, desc, msi_addr);
                        break;
                case IOMMU_COOKIE_IOMMUFD:
                        ret = iommufd_sw_msi(group->domain, desc, msi_addr);
                        break;
                default:
                        ret = -EOPNOTSUPP;
                        break;
                }
        }
        mutex_unlock(&group->mutex);
        return ret;
}
#endif /* CONFIG_IRQ_MSI_IOMMU */