From: Jiri Pirko jiri@nvidia.com
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 jiri@nvidia.com --- 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
On Thu, Apr 2, 2026 at 7:11 AM Jiri Pirko jiri@resnulli.us wrote:
From: Jiri Pirko jiri@nvidia.com
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 jiri@nvidia.com
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
"non-CoCo VM configurations"
- not registered.
Doesn't seem like you need to wrap this line.
with that: Reviewed-by: T.J.Mercier tjmercier@google.com
- 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
Each paragraph starting with '-' confused me for a second there. Those aren't part of the diff. :)
Mon, Apr 06, 2026 at 10:20:33PM +0200, tjmercier@google.com wrote:
On Thu, Apr 2, 2026 at 7:11 AM Jiri Pirko jiri@resnulli.us wrote:
From: Jiri Pirko jiri@nvidia.com
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 jiri@nvidia.com
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
"non-CoCo VM configurations"
- not registered.
Doesn't seem like you need to wrap this line.
with that: Reviewed-by: T.J.Mercier tjmercier@google.com
Okay. Thanks!
- 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
Each paragraph starting with '-' confused me for a second there. Those aren't part of the diff. :)
linaro-mm-sig@lists.linaro.org
-
Jiri Pirko -
T.J. Mercier