Re: [PATCH v2 10/11] coco: arm64: dma: Update force_dma_unencrypted for accepted devices

[Jonathan Cameron <jonathan.cameron@huawei.com>]

On Mon, 17 Nov 2025 19:30:06 +0530
"Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org> wrote:

> This change updates the DMA behavior for accepted devices by assuming
> they access only private memory. Currently, the DMA API does not provide
> a mechanism for allocating shared memory that can be accessed by both
> the secure realm and the non-secure host.
> 
> Accepted devices are therefore expected to operate entirely within the
> private memory space. As of now, there is no API in the DMA layer that
> allows such devices to explicitly request shared memory allocations for
> coherent data exchange with the host.

Isn't this sentence a bit of a repeat of the one at the end of the
1st paragraph.

> 
> If future use cases require accepted devices to interact with shared
> memory— for example, for host-device communication, we will need to
> extend the DMA interface to support such allocation semantics. This
> commit lays the groundwork for that by clearly defining the current
> assumption and isolating the enforcement to force_dma_unencrypted.
> 
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>