diff options
| author | Jiri Pirko <jiri@nvidia.com> | 2026-03-25 20:23:51 +0100 |
|---|---|---|
| committer | Marek Szyprowski <m.szyprowski@samsung.com> | 2026-04-02 07:29:33 +0200 |
| commit | f0548044a02630402d374df195ed3af4cc5e4711 (patch) | |
| tree | 98713be309d9a76bf648538dff3aa1548f258a8b /include/linux | |
| parent | 27e2e9b9b49c5d5260969168b86cd238254b9105 (diff) | |
dma-mapping: introduce DMA_ATTR_CC_SHARED for shared memory
Current CC designs don't place a vIOMMU in front of untrusted devices.
Instead, the DMA API forces all untrusted device DMA through swiotlb
bounce buffers (is_swiotlb_force_bounce()) which copies data into
shared memory on behalf of the device.
When a caller has already arranged for the memory to be shared
via set_memory_decrypted(), the DMA API needs to know so it can map
directly using the unencrypted physical address rather than bounce
buffering. Following the pattern of DMA_ATTR_MMIO, add
DMA_ATTR_CC_SHARED for this purpose. Like the MMIO case, only the
caller knows what kind of memory it has and must inform the DMA API
for it to work correctly.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260325192352.437608-2-jiri@resnulli.us
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/dma-mapping.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 677c51ab7510..db8ab24a54f4 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -92,6 +92,16 @@ * flushing. */ #define DMA_ATTR_REQUIRE_COHERENT (1UL << 12) +/* + * DMA_ATTR_CC_SHARED: Indicates the DMA mapping is shared (decrypted) for + * confidential computing guests. For normal system memory the caller must have + * called set_memory_decrypted(), and pgprot_decrypted must be used when + * creating CPU PTEs for the mapping. The same shared semantic may be passed + * to the vIOMMU when it sets up the IOPTE. For MMIO use together with + * DMA_ATTR_MMIO to indicate shared MMIO. Unless DMA_ATTR_MMIO is provided + * a struct page is required. + */ +#define DMA_ATTR_CC_SHARED (1UL << 13) /* * A dma_addr_t can hold any valid DMA or bus address for the platform. It can |