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CTRY:US; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:mail.nvidia.com; PTR:dc6edge1.nvidia.com; CAT:NONE; SFS:(13230025)(4636009)(396003)(376002)(136003)(346002)(39860400002)(451199018)(40470700004)(36840700001)(46966006)(40460700003)(83380400001)(110136005)(54906003)(47076005)(316002)(70586007)(41300700001)(70206006)(4326008)(8936002)(8676002)(6666004)(26005)(186003)(478600001)(2616005)(7696005)(336012)(86362001)(82310400005)(426003)(36756003)(356005)(2906002)(40480700001)(30864003)(36860700001)(5660300002)(7636003)(7416002)(82740400003); DIR:OUT; SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Feb 2023 07:05:37.5138 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 487f62dd-64d4-46ca-abe9-08db04ebe30b X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a; Ip=[216.228.117.160]; Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CO1NAM11FT098.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB6792 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org To prepare for an access->ioas replacement, move iommufd_access_create() call into vfio_iommufd_emulated_bind(), making it symmetric with the __vfio_iommufd_access_destroy() call in vfio_iommufd_emulated_unbind(). This means an access is created/destroyed by the bind()/unbind(), and the vfio_iommufd_emulated_attach_ioas() only updates the access->ioas pointer. Since there's no longer an ioas_id input for iommufd_access_create(), add a new helper iommufd_access_set_ioas() to set access->ioas. We can later add a "replace" feature simply to the new iommufd_access_set_ioas() too. Leaving the access->ioas in vfio_iommufd_emulated_attach_ioas(), however, can introduce some potential of a race condition during pin_/unpin_pages() call where access->ioas->iopt is getting referenced. So, add an ioas_lock to protect it. Note that the "refcount_dec(&access->ioas->obj.users)" line is also moved to the new iommufd_access_set_ioas() from iommufd_access_destroy_object() for symmetry. Without this change, the old_ioas would also lose the track of its refcount when the replace support is added. Signed-off-by: Nicolin Chen --- drivers/iommu/iommufd/device.c | 100 ++++++++++++++++++------ drivers/iommu/iommufd/iommufd_private.h | 1 + drivers/iommu/iommufd/selftest.c | 5 +- drivers/vfio/iommufd.c | 30 +++---- include/linux/iommufd.h | 3 +- 5 files changed, 96 insertions(+), 43 deletions(-) diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c index d81f93a321af..f4bd6f532a90 100644 --- a/drivers/iommu/iommufd/device.c +++ b/drivers/iommu/iommufd/device.c @@ -418,9 +418,9 @@ 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_access_set_ioas(access, 0); iommufd_ctx_put(access->ictx); - refcount_dec(&access->ioas->obj.users); + mutex_destroy(&access->ioas_lock); } /** @@ -437,12 +437,10 @@ void iommufd_access_destroy_object(struct iommufd_object *obj) * The provided ops are required to use iommufd_access_pin_pages(). */ struct iommufd_access * -iommufd_access_create(struct iommufd_ctx *ictx, u32 ioas_id, +iommufd_access_create(struct iommufd_ctx *ictx, 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 @@ -455,33 +453,18 @@ iommufd_access_create(struct iommufd_ctx *ictx, u32 ioas_id, 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); + mutex_init(&access->ioas_lock); 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); @@ -500,6 +483,50 @@ void iommufd_access_destroy(struct iommufd_access *access) } EXPORT_SYMBOL_NS_GPL(iommufd_access_destroy, IOMMUFD); +int iommufd_access_set_ioas(struct iommufd_access *access, u32 ioas_id) +{ + struct iommufd_ioas *new_ioas = NULL, *cur_ioas; + struct iommufd_ctx *ictx = access->ictx; + struct iommufd_object *obj; + int rc = 0; + + if (ioas_id) { + obj = iommufd_get_object(ictx, ioas_id, IOMMUFD_OBJ_IOAS); + if (IS_ERR(obj)) + return PTR_ERR(obj); + new_ioas = container_of(obj, struct iommufd_ioas, obj); + } + + mutex_lock(&access->ioas_lock); + cur_ioas = access->ioas; + if (cur_ioas == new_ioas) + goto out_unlock; + + if (new_ioas) { + rc = iopt_add_access(&new_ioas->iopt, access); + if (rc) + goto out_unlock; + iommufd_ref_to_users(obj); + } + + if (cur_ioas) { + iopt_remove_access(&cur_ioas->iopt, access); + refcount_dec(&cur_ioas->obj.users); + } + + access->ioas = new_ioas; + mutex_unlock(&access->ioas_lock); + + return 0; + +out_unlock: + mutex_unlock(&access->ioas_lock); + if (new_ioas) + iommufd_put_object(obj); + return rc; +} +EXPORT_SYMBOL_NS_GPL(iommufd_access_set_ioas, IOMMUFD); + /** * iommufd_access_notify_unmap - Notify users of an iopt to stop using it * @iopt: iopt to work on @@ -550,8 +577,8 @@ void iommufd_access_notify_unmap(struct io_pagetable *iopt, unsigned long iova, 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; + struct io_pagetable *iopt; unsigned long last_iova; struct iopt_area *area; @@ -559,6 +586,13 @@ void iommufd_access_unpin_pages(struct iommufd_access *access, WARN_ON(check_add_overflow(iova, length - 1, &last_iova))) return; + mutex_lock(&access->ioas_lock); + if (!access->ioas) { + mutex_unlock(&access->ioas_lock); + return; + } + iopt = &access->ioas->iopt; + down_read(&iopt->iova_rwsem); iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) iopt_area_remove_access( @@ -568,6 +602,7 @@ void iommufd_access_unpin_pages(struct iommufd_access *access, min(last_iova, iopt_area_last_iova(area)))); up_read(&iopt->iova_rwsem); WARN_ON(!iopt_area_contig_done(&iter)); + mutex_unlock(&access->ioas_lock); } EXPORT_SYMBOL_NS_GPL(iommufd_access_unpin_pages, IOMMUFD); @@ -613,8 +648,8 @@ 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; + struct io_pagetable *iopt; unsigned long last_iova; struct iopt_area *area; int rc; @@ -629,6 +664,13 @@ int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova, if (check_add_overflow(iova, length - 1, &last_iova)) return -EOVERFLOW; + mutex_lock(&access->ioas_lock); + if (!access->ioas) { + mutex_unlock(&access->ioas_lock); + return -ENOENT; + } + iopt = &access->ioas->iopt; + 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)); @@ -659,6 +701,7 @@ int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova, } up_read(&iopt->iova_rwsem); + mutex_unlock(&access->ioas_lock); return 0; err_remove: @@ -673,6 +716,7 @@ int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova, iopt_area_last_iova(area)))); } up_read(&iopt->iova_rwsem); + mutex_unlock(&access->ioas_lock); return rc; } EXPORT_SYMBOL_NS_GPL(iommufd_access_pin_pages, IOMMUFD); @@ -692,8 +736,8 @@ EXPORT_SYMBOL_NS_GPL(iommufd_access_pin_pages, IOMMUFD); 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 io_pagetable *iopt; struct iopt_area *area; unsigned long last_iova; int rc; @@ -703,6 +747,13 @@ int iommufd_access_rw(struct iommufd_access *access, unsigned long iova, if (check_add_overflow(iova, length - 1, &last_iova)) return -EOVERFLOW; + mutex_lock(&access->ioas_lock); + if (!access->ioas) { + mutex_unlock(&access->ioas_lock); + return -ENOENT; + } + iopt = &access->ioas->iopt; + 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)); @@ -729,6 +780,7 @@ int iommufd_access_rw(struct iommufd_access *access, unsigned long iova, rc = -ENOENT; err_out: up_read(&iopt->iova_rwsem); + mutex_unlock(&access->ioas_lock); return rc; } EXPORT_SYMBOL_NS_GPL(iommufd_access_rw, IOMMUFD); diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index 222e86591f8a..2f4bb106bac6 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -261,6 +261,7 @@ struct iommufd_access { struct iommufd_object obj; struct iommufd_ctx *ictx; struct iommufd_ioas *ioas; + struct mutex ioas_lock; const struct iommufd_access_ops *ops; void *data; unsigned long iova_alignment; diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c index cfb5fe9a5e0e..db4011bdc8a9 100644 --- a/drivers/iommu/iommufd/selftest.c +++ b/drivers/iommu/iommufd/selftest.c @@ -571,7 +571,7 @@ static int iommufd_test_create_access(struct iommufd_ucmd *ucmd, } access = iommufd_access_create( - ucmd->ictx, ioas_id, + ucmd->ictx, (flags & MOCK_FLAGS_ACCESS_CREATE_NEEDS_PIN_PAGES) ? &selftest_access_ops_pin : &selftest_access_ops, @@ -580,6 +580,9 @@ static int iommufd_test_create_access(struct iommufd_ucmd *ucmd, rc = PTR_ERR(access); goto out_put_fdno; } + rc = iommufd_access_set_ioas(access, ioas_id); + if (rc) + goto out_destroy; cmd->create_access.out_access_fd = fdno; rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd)); if (rc) diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c index 412644fdbf16..78a8e4641cbf 100644 --- a/drivers/vfio/iommufd.c +++ b/drivers/vfio/iommufd.c @@ -144,10 +144,19 @@ static const struct iommufd_access_ops vfio_user_ops = { int vfio_iommufd_emulated_bind(struct vfio_device *vdev, struct iommufd_ctx *ictx, u32 *out_device_id) { + struct iommufd_access *user; + lockdep_assert_held(&vdev->dev_set->lock); - vdev->iommufd_ictx = ictx; iommufd_ctx_get(ictx); + user = iommufd_access_create(vdev->iommufd_ictx, &vfio_user_ops, vdev); + if (IS_ERR(user)) { + iommufd_ctx_put(vdev->iommufd_ictx); + return PTR_ERR(user); + } + iommufd_access_set_ioas(user, 0); + vdev->iommufd_access = user; + vdev->iommufd_ictx = ictx; return 0; } EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_bind); @@ -171,27 +180,14 @@ EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_unbind); int vfio_iommufd_emulated_attach_ioas(struct vfio_device *vdev, u32 *pt_id) { - struct iommufd_access *user; - lockdep_assert_held(&vdev->dev_set->lock); if (!vdev->iommufd_ictx) return -EINVAL; + if (!vdev->iommufd_access) + return -ENOENT; - if (!pt_id) { - if (vdev->iommufd_access) - __vfio_iommufd_access_destroy(vdev); - return 0; - } - - if (vdev->iommufd_access) - return -EBUSY; - - user = iommufd_access_create(vdev->iommufd_ictx, *pt_id, &vfio_user_ops, - vdev); - if (IS_ERR(user)) - return PTR_ERR(user); - vdev->iommufd_access = user; + iommufd_access_set_ioas(vdev->iommufd_access, *pt_id); return 0; } EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_attach_ioas); diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h index 650d45629647..0e30f2ce27cd 100644 --- a/include/linux/iommufd.h +++ b/include/linux/iommufd.h @@ -40,9 +40,10 @@ enum { }; struct iommufd_access * -iommufd_access_create(struct iommufd_ctx *ictx, u32 ioas_id, +iommufd_access_create(struct iommufd_ctx *ictx, const struct iommufd_access_ops *ops, void *data); void iommufd_access_destroy(struct iommufd_access *access); +int iommufd_access_set_ioas(struct iommufd_access *access, u32 ioas_id); void iommufd_ctx_get(struct iommufd_ctx *ictx);