Re: [PATCH v5 2/9] scatterlist: Add a flag for the restricted memory

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

Il 15/05/24 13:23, Yong Wu ha scritto:
> Introduce a FLAG for the restricted memory which means the memory is
> protected by TEE or hypervisor, then it's inaccessiable for kernel.
> 
> Currently we don't use sg_dma_unmark_restricted, thus this interface
> has not been added.
> 
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
>   include/linux/scatterlist.h | 34 ++++++++++++++++++++++++++++++++++
>   1 file changed, 34 insertions(+)
> 
> diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
> index 77df3d7b18a6..a6ad9018eca0 100644
> --- a/include/linux/scatterlist.h
> +++ b/include/linux/scatterlist.h
> @@ -282,6 +282,7 @@ static inline void sg_unmark_end(struct scatterlist *sg)
>   
>   #define SG_DMA_BUS_ADDRESS	(1 << 0)
>   #define SG_DMA_SWIOTLB		(1 << 1)
> +#define SG_DMA_RESTRICTED	(2 << 1)

I think you wanted to write (1 << 2) here :-)

Cheers,
Angelo

>   
>   /**
>    * sg_dma_is_bus_address - Return whether a given segment was marked
> @@ -352,6 +353,31 @@ static inline void sg_dma_mark_swiotlb(struct scatterlist *sg)
>   	sg->dma_flags |= SG_DMA_SWIOTLB;
>   }
>   
> +/**
> + * sg_dma_mark_restricted - Mark the scatterlist for restricted buffer.
> + * @sg:		SG entry
> + *
> + * Description:
> + *   Marks a a scatterlist for the restricted buffer that may be inaccessiable
> + *   in kernel if it is protected.
> + */
> +static inline void sg_dma_mark_restricted(struct scatterlist *sg)
> +{
> +	sg->dma_flags |= SG_DMA_RESTRICTED;
> +}
> +
> +/**
> + * sg_dma_is_restricted - Return whether the scatterlist was marked as restricted
> + *                        buffer.
> + * @sg:		SG entry
> + *
> + * Description:
> + *   Returns true if the scatterlist was marked as restricted buffer.
> + */
> +static inline bool sg_dma_is_restricted(struct scatterlist *sg)
> +{
> +	return sg->dma_flags & SG_DMA_RESTRICTED;
> +}
>   #else
>   
>   static inline bool sg_dma_is_bus_address(struct scatterlist *sg)
> @@ -372,6 +398,14 @@ static inline void sg_dma_mark_swiotlb(struct scatterlist *sg)
>   {
>   }
>   
> +static inline bool sg_dma_is_restricted(struct scatterlist *sg)
> +{
> +	return false;
> +}
> +
> +static inline void sg_dma_mark_restrited(struct scatterlist *sg)
> +{
> +}
>   #endif	/* CONFIG_NEED_SG_DMA_FLAGS */
>   
>   /**