[PATCH v8 02/11] iommu: Introduce a union to struct iommu_resv_region

[Robin Murphy]

On 2022-02-21 15:43, Shameer Kolothum wrote:
> A union is introduced to struct iommu_resv_region to hold
> any firmware specific data. This is in preparation to add
> support for IORT RMR reserve regions and the union now holds
> the RMR specific information.
> 
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
> ---
>   include/linux/iommu.h | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index de0c57a567c8..b06952a75f95 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -126,6 +126,11 @@ enum iommu_resv_type {
>   	IOMMU_RESV_SW_MSI,
>   };
>   
> +struct iommu_iort_rmr_data {
> +	u32 *sids;	/* Stream Ids associated with IORT RMR entry */

Please make this const.

Further nit: capitalisation of "IDs" in the comment, otherwise I might 
worry about the possibility of Stream Egos too :P

> +	u32 num_sids;
> +};
> +
>   /**
>    * struct iommu_resv_region - descriptor for a reserved memory region
>    * @list: Linked list pointers
> @@ -133,6 +138,7 @@ enum iommu_resv_type {
>    * @length: Length of the region in bytes
>    * @prot: IOMMU Protection flags (READ/WRITE/...)
>    * @type: Type of the reserved region
> + * @fw_data: FW specific reserved region data

Nit: we've got plenty of room to spell out "Firmware-specific", and it 
never hurts to make documentation as easy to read as possible.

Thanks,
Robin.

>    */
>   struct iommu_resv_region {
>   	struct list_head	list;
> @@ -140,6 +146,9 @@ struct iommu_resv_region {
>   	size_t			length;
>   	int			prot;
>   	enum iommu_resv_type	type;
> +	union {
> +		struct iommu_iort_rmr_data rmr;
> +	} fw_data;
>   };
>   
>   /**