[PATCH v7 16/22] dma-direct: make dma_direct_map_phys() honor DMA_ATTR_CC_SHARED

[Jason Gunthorpe]

On Wed, Jul 01, 2026 at 11:19:20AM +0530, Aneesh Kumar K.V (Arm) wrote:
> @@ -88,37 +88,40 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev,
>  {
>  	dma_addr_t dma_addr;
>  
> +	/*
> +	 * For a device requiring unencrypted DMA, MMIO memory is treated
> +	 * as shared by default.
> +	 */
> +	if (force_dma_unencrypted(dev) && (attrs & DMA_ATTR_MMIO))
> +		attrs |= DMA_ATTR_CC_SHARED;
> +
>  	if (is_swiotlb_force_bounce(dev)) {
> -		if (!(attrs & DMA_ATTR_CC_SHARED)) {
> -			if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT))
> -				return DMA_MAPPING_ERROR;
> +		if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT))
> +			return DMA_MAPPING_ERROR;
>  
> -			return swiotlb_map(dev, phys, size, dir, attrs);
> -		}
> -	} else if (attrs & DMA_ATTR_CC_SHARED) {
> -		return DMA_MAPPING_ERROR;
> +		return swiotlb_map(dev, phys, size, dir, attrs);
>  	}
>  
> -	if (attrs & DMA_ATTR_MMIO) {
> -		dma_addr = phys;
> -		if (unlikely(!dma_capable(dev, dma_addr, size, false, attrs)))
> -			goto err_overflow;
> -	} else if (attrs & DMA_ATTR_CC_SHARED) {
> +	if (attrs & DMA_ATTR_CC_SHARED)
>  		dma_addr = phys_to_dma_unencrypted(dev, phys);
> +	else
> +		dma_addr = phys_to_dma_encrypted(dev, phys);

Maybe things should be adjusted so this can be
  phys_to_dma_direct(dev, phys, (attrs & DMA_ATTR_CC_SHARED) 

?

It would also be nice if swiotlb.c could do the same

Stated another way, maybe we should get rid of
phys_to_dma_unencrypted/encrypted() entirely and just have the bool
variation since that seems to be what everyone wants.

Jason