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path: root/drivers/iommu/iommufd/device.c
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Diffstat (limited to 'drivers/iommu/iommufd/device.c')
-rw-r--r--drivers/iommu/iommufd/device.c772
1 files changed, 772 insertions, 0 deletions
diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
new file mode 100644
index 000000000000..d81f93a321af
--- /dev/null
+++ b/drivers/iommu/iommufd/device.c
@@ -0,0 +1,772 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES
+ */
+#include <linux/iommufd.h>
+#include <linux/slab.h>
+#include <linux/iommu.h>
+#include <linux/irqdomain.h>
+
+#include "io_pagetable.h"
+#include "iommufd_private.h"
+
+static bool allow_unsafe_interrupts;
+module_param(allow_unsafe_interrupts, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(
+ allow_unsafe_interrupts,
+ "Allow IOMMUFD to bind to devices even if the platform cannot isolate "
+ "the MSI interrupt window. Enabling this is a security weakness.");
+
+/*
+ * A iommufd_device object represents the binding relationship between a
+ * consuming driver and the iommufd. These objects are created/destroyed by
+ * external drivers, not by userspace.
+ */
+struct iommufd_device {
+ struct iommufd_object obj;
+ struct iommufd_ctx *ictx;
+ struct iommufd_hw_pagetable *hwpt;
+ /* Head at iommufd_hw_pagetable::devices */
+ struct list_head devices_item;
+ /* always the physical device */
+ struct device *dev;
+ struct iommu_group *group;
+ bool enforce_cache_coherency;
+};
+
+void iommufd_device_destroy(struct iommufd_object *obj)
+{
+ struct iommufd_device *idev =
+ container_of(obj, struct iommufd_device, obj);
+
+ iommu_device_release_dma_owner(idev->dev);
+ iommu_group_put(idev->group);
+ iommufd_ctx_put(idev->ictx);
+}
+
+/**
+ * iommufd_device_bind - Bind a physical device to an iommu fd
+ * @ictx: iommufd file descriptor
+ * @dev: Pointer to a physical device struct
+ * @id: Output ID number to return to userspace for this device
+ *
+ * A successful bind establishes an ownership over the device and returns
+ * struct iommufd_device pointer, otherwise returns error pointer.
+ *
+ * A driver using this API must set driver_managed_dma and must not touch
+ * the device until this routine succeeds and establishes ownership.
+ *
+ * Binding a PCI device places the entire RID under iommufd control.
+ *
+ * The caller must undo this with iommufd_device_unbind()
+ */
+struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
+ struct device *dev, u32 *id)
+{
+ struct iommufd_device *idev;
+ struct iommu_group *group;
+ int rc;
+
+ /*
+ * iommufd always sets IOMMU_CACHE because we offer no way for userspace
+ * to restore cache coherency.
+ */
+ if (!device_iommu_capable(dev, IOMMU_CAP_CACHE_COHERENCY))
+ return ERR_PTR(-EINVAL);
+
+ group = iommu_group_get(dev);
+ if (!group)
+ return ERR_PTR(-ENODEV);
+
+ rc = iommu_device_claim_dma_owner(dev, ictx);
+ if (rc)
+ goto out_group_put;
+
+ idev = iommufd_object_alloc(ictx, idev, IOMMUFD_OBJ_DEVICE);
+ if (IS_ERR(idev)) {
+ rc = PTR_ERR(idev);
+ goto out_release_owner;
+ }
+ idev->ictx = ictx;
+ iommufd_ctx_get(ictx);
+ idev->dev = dev;
+ idev->enforce_cache_coherency =
+ device_iommu_capable(dev, IOMMU_CAP_ENFORCE_CACHE_COHERENCY);
+ /* The calling driver is a user until iommufd_device_unbind() */
+ refcount_inc(&idev->obj.users);
+ /* group refcount moves into iommufd_device */
+ idev->group = group;
+
+ /*
+ * If the caller fails after this success it must call
+ * iommufd_unbind_device() which is safe since we hold this refcount.
+ * This also means the device is a leaf in the graph and no other object
+ * can take a reference on it.
+ */
+ iommufd_object_finalize(ictx, &idev->obj);
+ *id = idev->obj.id;
+ return idev;
+
+out_release_owner:
+ iommu_device_release_dma_owner(dev);
+out_group_put:
+ iommu_group_put(group);
+ return ERR_PTR(rc);
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_device_bind, IOMMUFD);
+
+/**
+ * iommufd_device_unbind - Undo iommufd_device_bind()
+ * @idev: Device returned by iommufd_device_bind()
+ *
+ * Release the device from iommufd control. The DMA ownership will return back
+ * to unowned with DMA controlled by the DMA API. This invalidates the
+ * iommufd_device pointer, other APIs that consume it must not be called
+ * concurrently.
+ */
+void iommufd_device_unbind(struct iommufd_device *idev)
+{
+ bool was_destroyed;
+
+ was_destroyed = iommufd_object_destroy_user(idev->ictx, &idev->obj);
+ WARN_ON(!was_destroyed);
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_device_unbind, IOMMUFD);
+
+static int iommufd_device_setup_msi(struct iommufd_device *idev,
+ struct iommufd_hw_pagetable *hwpt,
+ phys_addr_t sw_msi_start)
+{
+ int rc;
+
+ /*
+ * If the IOMMU driver gives a IOMMU_RESV_SW_MSI then it is asking us to
+ * call iommu_get_msi_cookie() on its behalf. This is necessary to setup
+ * the MSI window so iommu_dma_prepare_msi() can install pages into our
+ * domain after request_irq(). If it is not done interrupts will not
+ * work on this domain.
+ *
+ * FIXME: This is conceptually broken for iommufd since we want to allow
+ * userspace to change the domains, eg switch from an identity IOAS to a
+ * DMA IOAS. There is currently no way to create a MSI window that
+ * matches what the IRQ layer actually expects in a newly created
+ * domain.
+ */
+ if (sw_msi_start != PHYS_ADDR_MAX && !hwpt->msi_cookie) {
+ rc = iommu_get_msi_cookie(hwpt->domain, sw_msi_start);
+ if (rc)
+ return rc;
+
+ /*
+ * iommu_get_msi_cookie() can only be called once per domain,
+ * it returns -EBUSY on later calls.
+ */
+ hwpt->msi_cookie = true;
+ }
+
+ /*
+ * For historical compat with VFIO the insecure interrupt path is
+ * allowed if the module parameter is set. Insecure means that a MemWr
+ * operation from the device (eg a simple DMA) cannot trigger an
+ * interrupt outside this iommufd context.
+ */
+ if (!device_iommu_capable(idev->dev, IOMMU_CAP_INTR_REMAP) &&
+ !irq_domain_check_msi_remap()) {
+ if (!allow_unsafe_interrupts)
+ return -EPERM;
+
+ dev_warn(
+ idev->dev,
+ "MSI interrupts are not secure, they cannot be isolated by the platform. "
+ "Check that platform features like interrupt remapping are enabled. "
+ "Use the \"allow_unsafe_interrupts\" module parameter to override\n");
+ }
+ return 0;
+}
+
+static bool iommufd_hw_pagetable_has_group(struct iommufd_hw_pagetable *hwpt,
+ struct iommu_group *group)
+{
+ struct iommufd_device *cur_dev;
+
+ list_for_each_entry(cur_dev, &hwpt->devices, devices_item)
+ if (cur_dev->group == group)
+ return true;
+ return false;
+}
+
+static int iommufd_device_do_attach(struct iommufd_device *idev,
+ struct iommufd_hw_pagetable *hwpt)
+{
+ phys_addr_t sw_msi_start = PHYS_ADDR_MAX;
+ int rc;
+
+ mutex_lock(&hwpt->devices_lock);
+
+ /*
+ * Try to upgrade the domain we have, it is an iommu driver bug to
+ * report IOMMU_CAP_ENFORCE_CACHE_COHERENCY but fail
+ * enforce_cache_coherency when there are no devices attached to the
+ * domain.
+ */
+ if (idev->enforce_cache_coherency && !hwpt->enforce_cache_coherency) {
+ if (hwpt->domain->ops->enforce_cache_coherency)
+ hwpt->enforce_cache_coherency =
+ hwpt->domain->ops->enforce_cache_coherency(
+ hwpt->domain);
+ if (!hwpt->enforce_cache_coherency) {
+ WARN_ON(list_empty(&hwpt->devices));
+ rc = -EINVAL;
+ goto out_unlock;
+ }
+ }
+
+ rc = iopt_table_enforce_group_resv_regions(&hwpt->ioas->iopt, idev->dev,
+ idev->group, &sw_msi_start);
+ if (rc)
+ goto out_unlock;
+
+ rc = iommufd_device_setup_msi(idev, hwpt, sw_msi_start);
+ if (rc)
+ goto out_iova;
+
+ /*
+ * FIXME: Hack around missing a device-centric iommu api, only attach to
+ * the group once for the first device that is in the group.
+ */
+ if (!iommufd_hw_pagetable_has_group(hwpt, idev->group)) {
+ rc = iommu_attach_group(hwpt->domain, idev->group);
+ if (rc)
+ goto out_iova;
+
+ if (list_empty(&hwpt->devices)) {
+ rc = iopt_table_add_domain(&hwpt->ioas->iopt,
+ hwpt->domain);
+ if (rc)
+ goto out_detach;
+ }
+ }
+
+ idev->hwpt = hwpt;
+ refcount_inc(&hwpt->obj.users);
+ list_add(&idev->devices_item, &hwpt->devices);
+ mutex_unlock(&hwpt->devices_lock);
+ return 0;
+
+out_detach:
+ iommu_detach_group(hwpt->domain, idev->group);
+out_iova:
+ iopt_remove_reserved_iova(&hwpt->ioas->iopt, idev->dev);
+out_unlock:
+ mutex_unlock(&hwpt->devices_lock);
+ return rc;
+}
+
+/*
+ * When automatically managing the domains we search for a compatible domain in
+ * the iopt and if one is found use it, otherwise create a new domain.
+ * Automatic domain selection will never pick a manually created domain.
+ */
+static int iommufd_device_auto_get_domain(struct iommufd_device *idev,
+ struct iommufd_ioas *ioas)
+{
+ struct iommufd_hw_pagetable *hwpt;
+ int rc;
+
+ /*
+ * There is no differentiation when domains are allocated, so any domain
+ * that is willing to attach to the device is interchangeable with any
+ * other.
+ */
+ mutex_lock(&ioas->mutex);
+ list_for_each_entry(hwpt, &ioas->hwpt_list, hwpt_item) {
+ if (!hwpt->auto_domain)
+ continue;
+
+ rc = iommufd_device_do_attach(idev, hwpt);
+
+ /*
+ * -EINVAL means the domain is incompatible with the device.
+ * Other error codes should propagate to userspace as failure.
+ * Success means the domain is attached.
+ */
+ if (rc == -EINVAL)
+ continue;
+ goto out_unlock;
+ }
+
+ hwpt = iommufd_hw_pagetable_alloc(idev->ictx, ioas, idev->dev);
+ if (IS_ERR(hwpt)) {
+ rc = PTR_ERR(hwpt);
+ goto out_unlock;
+ }
+ hwpt->auto_domain = true;
+
+ rc = iommufd_device_do_attach(idev, hwpt);
+ if (rc)
+ goto out_abort;
+ list_add_tail(&hwpt->hwpt_item, &ioas->hwpt_list);
+
+ mutex_unlock(&ioas->mutex);
+ iommufd_object_finalize(idev->ictx, &hwpt->obj);
+ return 0;
+
+out_abort:
+ iommufd_object_abort_and_destroy(idev->ictx, &hwpt->obj);
+out_unlock:
+ mutex_unlock(&ioas->mutex);
+ return rc;
+}
+
+/**
+ * iommufd_device_attach - Connect a device from an iommu_domain
+ * @idev: device to attach
+ * @pt_id: Input a IOMMUFD_OBJ_IOAS, or IOMMUFD_OBJ_HW_PAGETABLE
+ * Output the IOMMUFD_OBJ_HW_PAGETABLE ID
+ *
+ * This connects the device to an iommu_domain, either automatically or manually
+ * selected. Once this completes the device could do DMA.
+ *
+ * The caller should return the resulting pt_id back to userspace.
+ * This function is undone by calling iommufd_device_detach().
+ */
+int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id)
+{
+ struct iommufd_object *pt_obj;
+ int rc;
+
+ pt_obj = iommufd_get_object(idev->ictx, *pt_id, IOMMUFD_OBJ_ANY);
+ if (IS_ERR(pt_obj))
+ return PTR_ERR(pt_obj);
+
+ switch (pt_obj->type) {
+ case IOMMUFD_OBJ_HW_PAGETABLE: {
+ struct iommufd_hw_pagetable *hwpt =
+ container_of(pt_obj, struct iommufd_hw_pagetable, obj);
+
+ rc = iommufd_device_do_attach(idev, hwpt);
+ if (rc)
+ goto out_put_pt_obj;
+
+ mutex_lock(&hwpt->ioas->mutex);
+ list_add_tail(&hwpt->hwpt_item, &hwpt->ioas->hwpt_list);
+ mutex_unlock(&hwpt->ioas->mutex);
+ break;
+ }
+ case IOMMUFD_OBJ_IOAS: {
+ struct iommufd_ioas *ioas =
+ container_of(pt_obj, struct iommufd_ioas, obj);
+
+ rc = iommufd_device_auto_get_domain(idev, ioas);
+ if (rc)
+ goto out_put_pt_obj;
+ break;
+ }
+ default:
+ rc = -EINVAL;
+ goto out_put_pt_obj;
+ }
+
+ refcount_inc(&idev->obj.users);
+ *pt_id = idev->hwpt->obj.id;
+ rc = 0;
+
+out_put_pt_obj:
+ iommufd_put_object(pt_obj);
+ return rc;
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_device_attach, IOMMUFD);
+
+/**
+ * iommufd_device_detach - Disconnect a device to an iommu_domain
+ * @idev: device to detach
+ *
+ * Undo iommufd_device_attach(). This disconnects the idev from the previously
+ * attached pt_id. The device returns back to a blocked DMA translation.
+ */
+void iommufd_device_detach(struct iommufd_device *idev)
+{
+ struct iommufd_hw_pagetable *hwpt = idev->hwpt;
+
+ mutex_lock(&hwpt->ioas->mutex);
+ mutex_lock(&hwpt->devices_lock);
+ list_del(&idev->devices_item);
+ if (!iommufd_hw_pagetable_has_group(hwpt, idev->group)) {
+ if (list_empty(&hwpt->devices)) {
+ iopt_table_remove_domain(&hwpt->ioas->iopt,
+ hwpt->domain);
+ list_del(&hwpt->hwpt_item);
+ }
+ iommu_detach_group(hwpt->domain, idev->group);
+ }
+ iopt_remove_reserved_iova(&hwpt->ioas->iopt, idev->dev);
+ mutex_unlock(&hwpt->devices_lock);
+ mutex_unlock(&hwpt->ioas->mutex);
+
+ if (hwpt->auto_domain)
+ iommufd_object_destroy_user(idev->ictx, &hwpt->obj);
+ else
+ refcount_dec(&hwpt->obj.users);
+
+ idev->hwpt = NULL;
+
+ refcount_dec(&idev->obj.users);
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_device_detach, IOMMUFD);
+
+void iommufd_access_destroy_object(struct iommufd_object *obj)
+{
+ struct iommufd_access *access =
+ container_of(obj, struct iommufd_access, obj);
+
+ iopt_remove_access(&access->ioas->iopt, access);
+ iommufd_ctx_put(access->ictx);
+ refcount_dec(&access->ioas->obj.users);
+}
+
+/**
+ * iommufd_access_create - Create an iommufd_access
+ * @ictx: iommufd file descriptor
+ * @ioas_id: ID for a IOMMUFD_OBJ_IOAS
+ * @ops: Driver's ops to associate with the access
+ * @data: Opaque data to pass into ops functions
+ *
+ * An iommufd_access allows a driver to read/write to the IOAS without using
+ * DMA. The underlying CPU memory can be accessed using the
+ * iommufd_access_pin_pages() or iommufd_access_rw() functions.
+ *
+ * The provided ops are required to use iommufd_access_pin_pages().
+ */
+struct iommufd_access *
+iommufd_access_create(struct iommufd_ctx *ictx, u32 ioas_id,
+ const struct iommufd_access_ops *ops, void *data)
+{
+ struct iommufd_access *access;
+ struct iommufd_object *obj;
+ int rc;
+
+ /*
+ * There is no uAPI for the access object, but to keep things symmetric
+ * use the object infrastructure anyhow.
+ */
+ access = iommufd_object_alloc(ictx, access, IOMMUFD_OBJ_ACCESS);
+ if (IS_ERR(access))
+ return access;
+
+ access->data = data;
+ access->ops = ops;
+
+ obj = iommufd_get_object(ictx, ioas_id, IOMMUFD_OBJ_IOAS);
+ if (IS_ERR(obj)) {
+ rc = PTR_ERR(obj);
+ goto out_abort;
+ }
+ access->ioas = container_of(obj, struct iommufd_ioas, obj);
+ iommufd_ref_to_users(obj);
+
+ if (ops->needs_pin_pages)
+ access->iova_alignment = PAGE_SIZE;
+ else
+ access->iova_alignment = 1;
+ rc = iopt_add_access(&access->ioas->iopt, access);
+ if (rc)
+ goto out_put_ioas;
+
+ /* The calling driver is a user until iommufd_access_destroy() */
+ refcount_inc(&access->obj.users);
+ access->ictx = ictx;
+ iommufd_ctx_get(ictx);
+ iommufd_object_finalize(ictx, &access->obj);
+ return access;
+out_put_ioas:
+ refcount_dec(&access->ioas->obj.users);
+out_abort:
+ iommufd_object_abort(ictx, &access->obj);
+ return ERR_PTR(rc);
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_access_create, IOMMUFD);
+
+/**
+ * iommufd_access_destroy - Destroy an iommufd_access
+ * @access: The access to destroy
+ *
+ * The caller must stop using the access before destroying it.
+ */
+void iommufd_access_destroy(struct iommufd_access *access)
+{
+ bool was_destroyed;
+
+ was_destroyed = iommufd_object_destroy_user(access->ictx, &access->obj);
+ WARN_ON(!was_destroyed);
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_access_destroy, IOMMUFD);
+
+/**
+ * iommufd_access_notify_unmap - Notify users of an iopt to stop using it
+ * @iopt: iopt to work on
+ * @iova: Starting iova in the iopt
+ * @length: Number of bytes
+ *
+ * After this function returns there should be no users attached to the pages
+ * linked to this iopt that intersect with iova,length. Anyone that has attached
+ * a user through iopt_access_pages() needs to detach it through
+ * iommufd_access_unpin_pages() before this function returns.
+ *
+ * iommufd_access_destroy() will wait for any outstanding unmap callback to
+ * complete. Once iommufd_access_destroy() no unmap ops are running or will
+ * run in the future. Due to this a driver must not create locking that prevents
+ * unmap to complete while iommufd_access_destroy() is running.
+ */
+void iommufd_access_notify_unmap(struct io_pagetable *iopt, unsigned long iova,
+ unsigned long length)
+{
+ struct iommufd_ioas *ioas =
+ container_of(iopt, struct iommufd_ioas, iopt);
+ struct iommufd_access *access;
+ unsigned long index;
+
+ xa_lock(&ioas->iopt.access_list);
+ xa_for_each(&ioas->iopt.access_list, index, access) {
+ if (!iommufd_lock_obj(&access->obj))
+ continue;
+ xa_unlock(&ioas->iopt.access_list);
+
+ access->ops->unmap(access->data, iova, length);
+
+ iommufd_put_object(&access->obj);
+ xa_lock(&ioas->iopt.access_list);
+ }
+ xa_unlock(&ioas->iopt.access_list);
+}
+
+/**
+ * iommufd_access_unpin_pages() - Undo iommufd_access_pin_pages
+ * @access: IOAS access to act on
+ * @iova: Starting IOVA
+ * @length: Number of bytes to access
+ *
+ * Return the struct page's. The caller must stop accessing them before calling
+ * this. The iova/length must exactly match the one provided to access_pages.
+ */
+void iommufd_access_unpin_pages(struct iommufd_access *access,
+ unsigned long iova, unsigned long length)
+{
+ struct io_pagetable *iopt = &access->ioas->iopt;
+ struct iopt_area_contig_iter iter;
+ unsigned long last_iova;
+ struct iopt_area *area;
+
+ if (WARN_ON(!length) ||
+ WARN_ON(check_add_overflow(iova, length - 1, &last_iova)))
+ return;
+
+ down_read(&iopt->iova_rwsem);
+ iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova)
+ iopt_area_remove_access(
+ area, iopt_area_iova_to_index(area, iter.cur_iova),
+ iopt_area_iova_to_index(
+ area,
+ min(last_iova, iopt_area_last_iova(area))));
+ up_read(&iopt->iova_rwsem);
+ WARN_ON(!iopt_area_contig_done(&iter));
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_access_unpin_pages, IOMMUFD);
+
+static bool iopt_area_contig_is_aligned(struct iopt_area_contig_iter *iter)
+{
+ if (iopt_area_start_byte(iter->area, iter->cur_iova) % PAGE_SIZE)
+ return false;
+
+ if (!iopt_area_contig_done(iter) &&
+ (iopt_area_start_byte(iter->area, iopt_area_last_iova(iter->area)) %
+ PAGE_SIZE) != (PAGE_SIZE - 1))
+ return false;
+ return true;
+}
+
+static bool check_area_prot(struct iopt_area *area, unsigned int flags)
+{
+ if (flags & IOMMUFD_ACCESS_RW_WRITE)
+ return area->iommu_prot & IOMMU_WRITE;
+ return area->iommu_prot & IOMMU_READ;
+}
+
+/**
+ * iommufd_access_pin_pages() - Return a list of pages under the iova
+ * @access: IOAS access to act on
+ * @iova: Starting IOVA
+ * @length: Number of bytes to access
+ * @out_pages: Output page list
+ * @flags: IOPMMUFD_ACCESS_RW_* flags
+ *
+ * Reads @length bytes starting at iova and returns the struct page * pointers.
+ * These can be kmap'd by the caller for CPU access.
+ *
+ * The caller must perform iommufd_access_unpin_pages() when done to balance
+ * this.
+ *
+ * This API always requires a page aligned iova. This happens naturally if the
+ * ioas alignment is >= PAGE_SIZE and the iova is PAGE_SIZE aligned. However
+ * smaller alignments have corner cases where this API can fail on otherwise
+ * aligned iova.
+ */
+int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova,
+ unsigned long length, struct page **out_pages,
+ unsigned int flags)
+{
+ struct io_pagetable *iopt = &access->ioas->iopt;
+ struct iopt_area_contig_iter iter;
+ unsigned long last_iova;
+ struct iopt_area *area;
+ int rc;
+
+ /* Driver's ops don't support pin_pages */
+ if (IS_ENABLED(CONFIG_IOMMUFD_TEST) &&
+ WARN_ON(access->iova_alignment != PAGE_SIZE || !access->ops->unmap))
+ return -EINVAL;
+
+ if (!length)
+ return -EINVAL;
+ if (check_add_overflow(iova, length - 1, &last_iova))
+ return -EOVERFLOW;
+
+ down_read(&iopt->iova_rwsem);
+ iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) {
+ unsigned long last = min(last_iova, iopt_area_last_iova(area));
+ unsigned long last_index = iopt_area_iova_to_index(area, last);
+ unsigned long index =
+ iopt_area_iova_to_index(area, iter.cur_iova);
+
+ if (area->prevent_access ||
+ !iopt_area_contig_is_aligned(&iter)) {
+ rc = -EINVAL;
+ goto err_remove;
+ }
+
+ if (!check_area_prot(area, flags)) {
+ rc = -EPERM;
+ goto err_remove;
+ }
+
+ rc = iopt_area_add_access(area, index, last_index, out_pages,
+ flags);
+ if (rc)
+ goto err_remove;
+ out_pages += last_index - index + 1;
+ }
+ if (!iopt_area_contig_done(&iter)) {
+ rc = -ENOENT;
+ goto err_remove;
+ }
+
+ up_read(&iopt->iova_rwsem);
+ return 0;
+
+err_remove:
+ if (iova < iter.cur_iova) {
+ last_iova = iter.cur_iova - 1;
+ iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova)
+ iopt_area_remove_access(
+ area,
+ iopt_area_iova_to_index(area, iter.cur_iova),
+ iopt_area_iova_to_index(
+ area, min(last_iova,
+ iopt_area_last_iova(area))));
+ }
+ up_read(&iopt->iova_rwsem);
+ return rc;
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_access_pin_pages, IOMMUFD);
+
+/**
+ * iommufd_access_rw - Read or write data under the iova
+ * @access: IOAS access to act on
+ * @iova: Starting IOVA
+ * @data: Kernel buffer to copy to/from
+ * @length: Number of bytes to access
+ * @flags: IOMMUFD_ACCESS_RW_* flags
+ *
+ * Copy kernel to/from data into the range given by IOVA/length. If flags
+ * indicates IOMMUFD_ACCESS_RW_KTHREAD then a large copy can be optimized
+ * by changing it into copy_to/from_user().
+ */
+int iommufd_access_rw(struct iommufd_access *access, unsigned long iova,
+ void *data, size_t length, unsigned int flags)
+{
+ struct io_pagetable *iopt = &access->ioas->iopt;
+ struct iopt_area_contig_iter iter;
+ struct iopt_area *area;
+ unsigned long last_iova;
+ int rc;
+
+ if (!length)
+ return -EINVAL;
+ if (check_add_overflow(iova, length - 1, &last_iova))
+ return -EOVERFLOW;
+
+ down_read(&iopt->iova_rwsem);
+ iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) {
+ unsigned long last = min(last_iova, iopt_area_last_iova(area));
+ unsigned long bytes = (last - iter.cur_iova) + 1;
+
+ if (area->prevent_access) {
+ rc = -EINVAL;
+ goto err_out;
+ }
+
+ if (!check_area_prot(area, flags)) {
+ rc = -EPERM;
+ goto err_out;
+ }
+
+ rc = iopt_pages_rw_access(
+ area->pages, iopt_area_start_byte(area, iter.cur_iova),
+ data, bytes, flags);
+ if (rc)
+ goto err_out;
+ data += bytes;
+ }
+ if (!iopt_area_contig_done(&iter))
+ rc = -ENOENT;
+err_out:
+ up_read(&iopt->iova_rwsem);
+ return rc;
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_access_rw, IOMMUFD);
+
+#ifdef CONFIG_IOMMUFD_TEST
+/*
+ * Creating a real iommufd_device is too hard, bypass creating a iommufd_device
+ * and go directly to attaching a domain.
+ */
+struct iommufd_hw_pagetable *
+iommufd_device_selftest_attach(struct iommufd_ctx *ictx,
+ struct iommufd_ioas *ioas,
+ struct device *mock_dev)
+{
+ struct iommufd_hw_pagetable *hwpt;
+ int rc;
+
+ hwpt = iommufd_hw_pagetable_alloc(ictx, ioas, mock_dev);
+ if (IS_ERR(hwpt))
+ return hwpt;
+
+ rc = iopt_table_add_domain(&hwpt->ioas->iopt, hwpt->domain);
+ if (rc)
+ goto out_hwpt;
+
+ refcount_inc(&hwpt->obj.users);
+ iommufd_object_finalize(ictx, &hwpt->obj);
+ return hwpt;
+
+out_hwpt:
+ iommufd_object_abort_and_destroy(ictx, &hwpt->obj);
+ return ERR_PTR(rc);
+}
+
+void iommufd_device_selftest_detach(struct iommufd_ctx *ictx,
+ struct iommufd_hw_pagetable *hwpt)
+{
+ iopt_table_remove_domain(&hwpt->ioas->iopt, hwpt->domain);
+ refcount_dec(&hwpt->obj.users);
+}
+#endif