On Thu, Jun 04, 2026 at 02:09:39PM +0530, Aneesh Kumar K.V (Arm) wrote:
This series propagates DMA_ATTR_CC_SHARED through the dma-direct,
dma-pool, and swiotlb paths so that encrypted and decrypted DMA buffers
are handled consistently.
Today, the direct DMA path mostly relies on force_dma_unencrypted() for
shared/decrypted buffer handling. This series consolidates the
force_dma_unencrypted() checks in the top-level functions and ensures
that the remaining DMA interfaces use DMA attributes to make the correct
decisions.
Please check Sashiko's reports, it has some good points:
https://sashiko.dev/#/patchset/20260604083959.1265923-1-aneesh.kumar@kernel.org
I think the main one is the swiotlb_tbl_map_single() changes which break
AMD SME host support. There cc_platform_has(CC_ATTR_MEM_ENCRYPT) is true
but force_dma_unencrypted() is false. Normally you'd not end up on this
path but you can have swiotlb=force.
Aneesh Kumar K.V (Arm) (20):
s390: Expose protected virtualization through cc_platform_has()
dma-direct: swiotlb: handle swiotlb alloc/free outside
__dma_direct_alloc_pages
dma-direct: use DMA_ATTR_CC_SHARED in alloc/free paths
dma-pool: track decrypted atomic pools and select them via attrs
dma: swiotlb: pass mapping attributes by reference
dma: swiotlb: track pool encryption state and honor DMA_ATTR_CC_SHARED
dma-mapping: make dma_pgprot() honor DMA_ATTR_CC_SHARED
dma-direct: pass attrs to dma_capable() for DMA_ATTR_CC_SHARED checks
dma-direct: make dma_direct_map_phys() honor DMA_ATTR_CC_SHARED
dma-direct: set decrypted flag for remapped DMA allocations
Patch 10 above...
dma-direct: select DMA address encoding from DMA_ATTR_CC_SHARED
dma-pool: fix page leak in atomic_pool_expand() cleanup
Patch 12...
dma-direct: rename ret to cpu_addr in alloc helpers
dma-direct: return struct page from dma_direct_alloc_from_pool()
iommu/dma: Check atomic pool allocation result directly
and I think patches 14, 15 are independent fixes. Some of them even have
Fixes: tags and Cc: stable. Please move them to the beginning of the
series to avoid inadvertent dependencies and make them harder to
backport. It's also easier to follow the series without random fixes for
mainline in the middle.
dma: swiotlb: free dynamic pools from process context
dma: swiotlb: handle set_memory_decrypted() failures
dma: free atomic pool pages by physical address
swiotlb: Preserve allocation virtual address for dynamic pools
swiotlb: remove unused SWIOTLB_FORCE flag
--
Catalin