Re: [PATCH v7 16/22] dma-direct: make dma_direct_map_phys() honor DMA_ATTR_CC_SHARED
From: Jason Gunthorpe <jgg@ziepe.ca>
Date: 2026-07-13 19:32:47
Also in:
linux-arm-kernel, linux-coco, linux-iommu, linux-s390, lkml
On Wed, Jul 01, 2026 at 11:19:20AM +0530, Aneesh Kumar K.V (Arm) wrote:
quoted hunk ↗ jump to hunk
@@ -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