Commit 15818b2c authored by Jiri Pirko's avatar Jiri Pirko Committed by Marek Szyprowski
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dma-buf: heaps: system: document system_cc_shared heap 



Document the system_cc_shared dma-buf heap that was introduced
recently. Describe its purpose, availability conditions and
relation to confidential computing VMs.

Signed-off-by: default avatarJiri Pirko <jiri@nvidia.com>
Reviewed-by: default avatarT.J.Mercier <tjmercier@google.com>
Acked-by: default avatarSumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260407092617.635223-1-jiri@resnulli.us
parent 78b30c50

Documentation/userspace-api/dma-buf-heaps.rst

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Original line number Diff line number Diff line
@@ -16,6 +16,13 @@ following heaps: 


 - The ``system`` heap allocates virtually contiguous, cacheable, buffers.



 - The ``system_cc_shared`` heap allocates virtually contiguous, cacheable,

   buffers using shared (decrypted) memory. It is only present on

   confidential computing (CoCo) VMs where memory encryption is active

   (e.g., AMD SEV, Intel TDX). The allocated pages have the encryption

   bit cleared, making them accessible for device DMA without TDISP

   support. On non-CoCo VM configurations, this heap is not registered.



 - The ``default_cma_region`` heap allocates physically contiguous,

   cacheable, buffers. Only present if a CMA region is present. Such a

   region is usually created either through the kernel commandline