diff options
Diffstat (limited to 'drivers/iommu/iommufd/device.c')
| -rw-r--r-- | drivers/iommu/iommufd/device.c | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c index 67cd00b4d926..06b6894b7706 100644 --- a/drivers/iommu/iommufd/device.c +++ b/drivers/iommu/iommufd/device.c @@ -6,6 +6,7 @@ #include <linux/iommu.h> #include <linux/irqdomain.h> +#include "io_pagetable.h" #include "iommufd_private.h" static bool allow_unsafe_interrupts; @@ -417,3 +418,318 @@ void iommufd_device_detach(struct iommufd_device *idev) 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; + + 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); |