On Mon, 24 Jul 2023 12:47:07 -0700
Nicolin Chen <nicolinc@xxxxxxxxxx> wrote:
> Now both the physical path and the emulated path should support an IO page
> table replacement. Call iommufd_device_replace/iommufd_access_replace(),
> when vdev->iommufd_attached is true.
>
> Also update the VFIO_DEVICE_ATTACH_IOMMUFD_PT kdoc in the uAPI header.
>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> ---
> drivers/vfio/iommufd.c | 11 ++++++-----
> include/uapi/linux/vfio.h | 6 ++++++
> 2 files changed, 12 insertions(+), 5 deletions(-)
Reviewed-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
>
> diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
> index 4d84904fd927..82eba6966fa5 100644
> --- a/drivers/vfio/iommufd.c
> +++ b/drivers/vfio/iommufd.c
> @@ -146,9 +146,9 @@ int vfio_iommufd_physical_attach_ioas(struct vfio_device *vdev, u32 *pt_id)
> return -EINVAL;
>
> if (vdev->iommufd_attached)
> - return -EBUSY;
> -
> - rc = iommufd_device_attach(vdev->iommufd_device, pt_id);
> + rc = iommufd_device_replace(vdev->iommufd_device, pt_id);
> + else
> + rc = iommufd_device_attach(vdev->iommufd_device, pt_id);
> if (rc)
> return rc;
> vdev->iommufd_attached = true;
> @@ -223,8 +223,9 @@ int vfio_iommufd_emulated_attach_ioas(struct vfio_device *vdev, u32 *pt_id)
> lockdep_assert_held(&vdev->dev_set->lock);
>
> if (vdev->iommufd_attached)
> - return -EBUSY;
> - rc = iommufd_access_attach(vdev->iommufd_access, *pt_id);
> + rc = iommufd_access_replace(vdev->iommufd_access, *pt_id);
> + else
> + rc = iommufd_access_attach(vdev->iommufd_access, *pt_id);
> if (rc)
> return rc;
> vdev->iommufd_attached = true;
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index fa06e3eb4955..537157ff8670 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -939,6 +939,12 @@ struct vfio_device_bind_iommufd {
> * Undo by VFIO_DEVICE_DETACH_IOMMUFD_PT or device fd close. This is only
> * allowed on cdev fds.
> *
> + * If a vfio device is currently attached to a valid hw_pagetable, without doing
> + * a VFIO_DEVICE_DETACH_IOMMUFD_PT, a second VFIO_DEVICE_ATTACH_IOMMUFD_PT ioctl
> + * passing in another hw_pagetable (hwpt) id is allowed. This action, also known
> + * as a hw_pagetable replacement, will replace the device's currently attached
> + * hw_pagetable with a new hw_pagetable corresponding to the given pt_id.
> + *
> * Return: 0 on success, -errno on failure.
> */
> struct vfio_device_attach_iommufd_pt {
