From: Jiri Pirko <[email protected]> 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: Jiri Pirko <[email protected]> --- Documentation/userspace-api/dma-buf-heaps.rst | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/Documentation/userspace-api/dma-buf-heaps.rst b/Documentation/userspace-api/dma-buf-heaps.rst index 05445c83b79a..591732393e7d 100644 --- a/Documentation/userspace-api/dma-buf-heaps.rst +++ b/Documentation/userspace-api/dma-buf-heaps.rst @@ -16,6 +16,14 @@ 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 VMs 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 -- 2.51.1
