[PATCH v3 2/6] iommufd: Create access in vfio_iommufd_emulated_bind()

Yi Liu
2023-03-27T09:34:33Z

From: Nicolin Chen <nicolinc@nvidia.com>

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.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Terrence Xu <terrence.xu@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
drivers/iommu/iommufd/device.c | 51 +++++++++++++++++++-------------
drivers/iommu/iommufd/selftest.c | 5 +++-
drivers/vfio/iommufd.c | 24 ++++++++++-----
include/linux/iommufd.h | 3 +-
4 files changed, 53 insertions(+), 30 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index a0c66f47a65a..6999a10b5496 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -412,9 +412,12 @@ 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);
}

/**
@@ -431,12 +434,10 @@ 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 +450,10 @@ 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 +461,6 @@ 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 +479,30 @@ 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 != NULL && access->ioas->obj.id != ioas_id)
+ 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 8667eb222cf1..1e89e1a8c5f0 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_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 db4efbd56042..0695a06db30d 100644
--- 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 c0b5b3ac34f1..155d3630aedc 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_attach(struct iommufd_access *access, u32 ioas_id);

void iommufd_ctx_get(struct iommufd_ctx *ictx);

--
2.34.1