Re: [PATCH v2 03/10] iommufd: Create access in vfio_iommufd_emulated_bind()

[Eric Farman <farman@xxxxxxxxxxxxx>]

On Tue, 2023-02-07 at 13:17 -0800, Nicolin Chen wrote:
...snip...
> diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
> index 026f81a87dd7..dc9feab73db7 100644
> --- a/drivers/vfio/iommufd.c
> +++ b/drivers/vfio/iommufd.c
> @@ -141,10 +141,19 @@ 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);

Matthew noticed a vfio-ccw and -ap regression that blames this patch.

Probably both the iommufd_access_create() and iommufd_ctx_put() calls
want the ictx variable itself, instead of the (uninitialized) pointer
in the vfio_device. (At least that gets -ccw and -ap working again.)

Thanks,
Eric

> +               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);