diff options
| author | Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org> | 2026-07-17 23:34:27 +0530 |
|---|---|---|
| committer | Marek Szyprowski <m.szyprowski@samsung.com> | 2026-07-31 08:40:58 +0200 |
| commit | a6e40900f0c68884c76b7a3ca404d7d52b1791d3 (patch) | |
| tree | 51b89faa3ae302c58d56de89dafdb38b9cae89e9 /include/linux | |
| parent | d4b9d593180c72cafa2f586379b99517f251e6bb (diff) | |
dma-mapping: Add internal shared allocation attribute
DMA_ATTR_CC_SHARED describes an existing DMA mapping whose backing memory
is already shared, or decrypted, for confidential computing. It is a
mapping attribute: callers use it to request a shared DMA address encoding
for memory that has already been prepared for shared DMA.
Allocation paths need a related but different state. Once the DMA core
decides that an allocation must use shared backing pages, the lower-level
allocation helpers need to select shared pools, decrypt newly allocated
pages, derive the DMA address with the shared-memory translation and
restore encryption on free. That state is internal to the DMA-mapping
implementation and should not be passed by drivers to dma_alloc_attrs().
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
Reviewed-by: Mostafa Saleh <smostafa@google.com>
Link: https://lore.kernel.org/r/20260717180442.110954-10-aneesh.kumar@kernel.org
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/dma-mapping.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index cc0823a99cfd..a3e880649fa4 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -104,6 +104,14 @@ #define DMA_ATTR_CC_SHARED (1UL << 13) /* + * __DMA_ATTR_ALLOC_CC_SHARED: Internal DMA-mapping attribute used by + * allocation paths that create shared (decrypted) backing pages for + * confidential computing guests. Drivers must not pass this attribute to + * dma_alloc_attrs(). + */ +#define __DMA_ATTR_ALLOC_CC_SHARED (1UL << 14) + +/* * A dma_addr_t can hold any valid DMA or bus address for the platform. It can * be given to a device to use as a DMA source or target. It is specific to a * given device and there may be a translation between the CPU physical address |