Re: [PATCH v3 11/12] iommufd: Define IOMMUFD_INVALID_ID in uapi

Alex Williamson
2023-04-04T21:02:20Z

On Sat, 1 Apr 2023 07:44:28 -0700
Yi Liu <yi.l.liu@intel.com> wrote:

> as there are IOMMUFD users that want to know check if an ID generated
> by IOMMUFD is valid or not. e.g. vfio-pci optionaly returns invalid
> dev_id to user in the VFIO_DEVICE_GET_PCI_HOT_RESET_INFO ioctl. User
> needs to check if the ID is valid or not.
>
> IOMMUFD_INVALID_ID is defined as 0 since the IDs generated by IOMMUFD
> starts from 0.
>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
> include/uapi/linux/iommufd.h | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
> index 98ebba80cfa1..aeae73a93833 100644
> --- a/include/uapi/linux/iommufd.h
> +++ b/include/uapi/linux/iommufd.h
> @@ -9,6 +9,9 @@
>
> #define IOMMUFD_TYPE (';')
>
> +/* IDs allocated by IOMMUFD starts from 0 */
> +#define IOMMUFD_INVALID_ID 0
> +
> /**
> * DOC: General ioctl format
> *

If allocation "starts from 0" then 0 is a valid id, no? Does allocation
start from 1, ie. skip 0? Thanks,

Alex