iommufd: Create access in vfio_iommufd_emulated_bind()

There are needs to created iommufd_access prior to have an IOAS and set
IOAS later. Like the vfio device cdev needs to have an iommufd object
to represent the bond (iommufd_access) and IOAS replacement.

Moves the iommufd_access_create() call into vfio_iommufd_emulated_bind(),
making it symmetric with the __vfio_iommufd_access_destroy() call in the
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 vfio_iommufd_emulated_bind() does not provide ioas_id, drop it from
the argument list of iommufd_access_create(). Instead, add a new access
API iommufd_access_attach() to set the access->ioas pointer. Also, set
vdev->iommufd_attached accordingly, similar to the physical pathway.

Link: https://lore.kernel.org/r/20230327093351.44505-3-yi.l.liu@intel.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Terrence Xu <terrence.xu@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index a0c66f47a65ada7639fb9c0bc6e6dffecd32102f..ff6fca0ea269b1dfa72dbb6c43678be7c3fc55c0 100644 (file)
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -412,15 +412,17 @@ 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);
+       if (access->ioas) {
+               iopt_remove_access(&access->ioas->iopt, access);
+               refcount_dec(&access->ioas->obj.users);
+               access->ioas = NULL;
+       }
        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
  *
@@ -431,12 +433,10 @@ 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
@@ -449,21 +449,10 @@ 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);
@@ -471,11 +460,6 @@ iommufd_access_create(struct iommufd_ctx *ictx, u32 ioas_id,
        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);
 
@@ -494,6 +478,30 @@ void iommufd_access_destroy(struct iommufd_access *access)
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_access_destroy, IOMMUFD);
 
+int iommufd_access_attach(struct iommufd_access *access, u32 ioas_id)
+{
+       struct iommufd_ioas *new_ioas;
+       int rc = 0;
+
+       if (access->ioas)
+               return -EINVAL;
+
+       new_ioas = iommufd_get_ioas(access->ictx, ioas_id);
+       if (IS_ERR(new_ioas))
+               return PTR_ERR(new_ioas);
+
+       rc = iopt_add_access(&new_ioas->iopt, access);
+       if (rc) {
+               iommufd_put_object(&new_ioas->obj);
+               return rc;
+       }
+       iommufd_ref_to_users(&new_ioas->obj);
+
+       access->ioas = new_ioas;
+       return 0;
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_access_attach, IOMMUFD);
+
 /**
  * iommufd_access_notify_unmap - Notify users of an iopt to stop using it
  * @iopt: iopt to work on

diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c
index 8667eb222cf1b72c65395cef00ce750fb3a8226a..1e89e1a8c5f0774564804dbe7e06ae3578259b2b 100644 (file)
--- 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_attach(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 db4efbd560425fafeac42b02b5fb2ef6b798028e..0695a06db30d9f92e524943ec3f8a6f021707e84 100644 (file)
--- a/drivers/vfio/iommufd.c
+++ b/drivers/vfio/iommufd.c
@@ -138,10 +138,18 @@ 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(ictx, &vfio_user_ops, vdev);
+       if (IS_ERR(user)) {
+               iommufd_ctx_put(ictx);
+               return PTR_ERR(user);
+       }
+       vdev->iommufd_access = user;
+       vdev->iommufd_ictx = ictx;
        return 0;
 }
 EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_bind);
@@ -152,6 +160,7 @@ void vfio_iommufd_emulated_unbind(struct vfio_device *vdev)
 
        if (vdev->iommufd_access) {
                iommufd_access_destroy(vdev->iommufd_access);
+               vdev->iommufd_attached = false;
                vdev->iommufd_access = NULL;
        }
        iommufd_ctx_put(vdev->iommufd_ictx);
@@ -161,15 +170,16 @@ EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_unbind);
 
 int vfio_iommufd_emulated_attach_ioas(struct vfio_device *vdev, u32 *pt_id)
 {
-       struct iommufd_access *user;
+       int rc;
 
        lockdep_assert_held(&vdev->dev_set->lock);
 
-       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;
+       if (vdev->iommufd_attached)
+               return -EBUSY;
+       rc = iommufd_access_attach(vdev->iommufd_access, *pt_id);
+       if (rc)
+               return rc;
+       vdev->iommufd_attached = true;
        return 0;
 }
 EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_attach_ioas);

diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index c0b5b3ac34f1e0316ee1a8b49c570067434a9c93..155d3630aedcd55110dfcd2b09c6684fa8eec989 100644 (file)
--- 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_attach(struct iommufd_access *access, u32 ioas_id);
 
 void iommufd_ctx_get(struct iommufd_ctx *ictx);