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

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 01/07/2026 06:49, Aneesh Kumar K.V (Arm) wrote:
> Teach dma_direct_map_phys() to select the DMA address encoding based on
> DMA_ATTR_CC_SHARED.
> 
> Use phys_to_dma_unencrypted() for decrypted mappings and
> phys_to_dma_encrypted() otherwise. If a device requires unencrypted DMA
> but the source physical address is still encrypted, force the mapping
> through swiotlb so the DMA address and backing memory attributes remain
> consistent.
> 
> Update the arm64, x86, s390 and powerpc secure-guest setup to not use
> swiotlb force option
> 
> Tested-by: Jiri Pirko <jiri@nvidia.com>
> Tested-by: Michael Kelley <mhklinux@outlook.com>
> Tested-by: Mostafa Saleh <smostafa@google.com>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
> ---
> Changes from v3:
> * Handle DMA_ATTR_MMIO
> ---
>   arch/arm64/mm/init.c                 |  4 +--
>   arch/powerpc/platforms/pseries/svm.c |  2 +-
>   arch/s390/mm/init.c                  |  2 +-
>   arch/x86/kernel/pci-dma.c            |  4 +--
>   kernel/dma/direct.c                  |  4 ++-
>   kernel/dma/direct.h                  | 45 +++++++++++++++-------------
>   6 files changed, 31 insertions(+), 30 deletions(-)
> 
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 97987f850a33..acf67c7064db 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -338,10 +338,8 @@ void __init arch_mm_preinit(void)
>   	unsigned int flags = SWIOTLB_VERBOSE;
>   	bool swiotlb = max_pfn > PFN_DOWN(arm64_dma_phys_limit);
>   
> -	if (is_realm_world()) {
> +	if (is_realm_world())
>   		swiotlb = true;
> -		flags |= SWIOTLB_FORCE;
> -	}
>   
>   	if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb) {
>   		/*


For arm64 CCA bits:

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>