Re: [PATCH v4 04/13] dma: swiotlb: track pool encryption state and honor DMA_ATTR_CC_SHARED

[Mostafa Saleh]

On Tue, May 12, 2026 at 10:05 AM Aneesh Kumar K.V (Arm)
<aneesh.kumar@xxxxxxxxxx> wrote:
> @@ -1411,6 +1436,16 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
>         if (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
>                 pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n");
>
> +       /*
> +        * if we are trying to swiotlb map a decrypted paddr or the paddr is encrypted
> +        * but the device is forcing decryption, use decrypted io_tlb_mem
> +        */
> +       if ((attrs & DMA_ATTR_CC_SHARED) || force_dma_unencrypted(dev))

I don't think swiotlb needs to know about force_dma_unencrypted(), the
dma/direct caller should have all the information to pass the
appropriate flags.

Thanks.
Mostafa

> +               require_decrypted = true;
> +
> +       if (require_decrypted != mem->unencrypted)
> +               return (phys_addr_t)DMA_MAPPING_ERROR;
> +