From 15818b2cd42df3cc886f4cc46acfab4d072dcacc Mon Sep 17 00:00:00 2001 From: Jiri Pirko Date: Tue, 7 Apr 2026 11:26:17 +0200 Subject: [PATCH] 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: Jiri Pirko Reviewed-by: T.J.Mercier Acked-by: Sumit Semwal Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/20260407092617.635223-1-jiri@resnulli.us --- Documentation/userspace-api/dma-buf-heaps.rst | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/Documentation/userspace-api/dma-buf-heaps.rst b/Documentation/userspace-api/dma-buf-heaps.rst index 05445c83b79a..f56b743cdb36 100644 --- a/Documentation/userspace-api/dma-buf-heaps.rst +++ b/Documentation/userspace-api/dma-buf-heaps.rst @@ -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