linux-kernel - Re: [PATCH v2] dma/pool: Ensure DMA_DIRECT

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Message-ID: <7b505aac-0b2d-40b4-9a0b-98b74b0bf987@samsung.com>
Date: Wed, 13 Aug 2025 11:24:49 +0200
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Shanker Donthineni <sdonthineni@...dia.com>, Catalin Marinas
	<catalin.marinas@....com>, Will Deacon <will@...nel.org>, Suzuki K Poulose
	<suzuki.poulose@....com>, Steven Price <steven.price@....com>,
	linux-arm-kernel@...ts.infradead.org
Cc: Robin Murphy <robin.murphy@....com>, Gavin Shan <gshan@...hat.com>, Mike
	Rapoport <rppt@...nel.org>, Vikram Sethi <vsethi@...dia.com>, Jason Sequeira
	<jsequeira@...dia.com>, Dev Jain <dev.jain@....com>, David Rientjes
	<rientjes@...gle.com>, linux-kernel@...r.kernel.org, iommu@...ts.linux.dev,
	stable@...r.kernel.org
Subject: Re: [PATCH v2] dma/pool: Ensure DMA_DIRECT_REMAP allocations are
 decrypted

On 11.08.2025 20:17, Shanker Donthineni wrote:
> When CONFIG_DMA_DIRECT_REMAP is enabled, atomic pool pages are
> remapped via dma_common_contiguous_remap() using the supplied
> pgprot. Currently, the mapping uses
> pgprot_dmacoherent(PAGE_KERNEL), which leaves the memory encrypted
> on systems with memory encryption enabled (e.g., ARM CCA Realms).
>
> This can cause the DMA layer to fail or crash when accessing the
> memory, as the underlying physical pages are not configured as
> expected.
>
> Fix this by requesting a decrypted mapping in the vmap() call:
> pgprot_decrypted(pgprot_dmacoherent(PAGE_KERNEL))
>
> This ensures that atomic pool memory is consistently mapped
> unencrypted.
>
> Cc: stable@...r.kernel.org
> Signed-off-by: Shanker Donthineni <sdonthineni@...dia.com>

Thanks, applied to dma-mapping-fixes branch.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland