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Thu, 4 Jun 2026 08:40:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780562441; bh=+B5f91SDYjAMs4Y9geXO5xScntRrhAje95uzpPpXQjE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dzQj+Xv1YAFhivBTK7CKWkM+0NQuzr0RN2f9LB9ULjUJFlIfftky7+KoKyQ6ybxAb kZq+RqQ2asniAHfXZsuPLq5Cl8ip0oTmOAqQn9C7X+nvS1coYG67x7Cpm3bSVL+bL5 vrepqvziucoNCPihmTW6n77YoFQWBwZ2w0MV4E2d9QIzNbohyIR9tfS9i0iaosR/eU Ipx7IIKwdgW1G7X8FTC8/8X8E5CF3blsI7qoIrOeeLUmOcsQfBnyhE14/6nLKxglOR QcTn9ne7mZ3pscR/8jBpwRPIxIH/OO/KhbSOctArSt0uYE7p88CBCpdkjgJ+ciwNBz 2iqe8OEs0HMTQ== From: "Aneesh Kumar K.V (Arm)" To: iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev Cc: "Aneesh Kumar K.V (Arm)" , Robin Murphy , Marek Szyprowski , Will Deacon , Marc Zyngier , Steven Price , Suzuki K Poulose , Catalin Marinas , Jiri Pirko , Jason Gunthorpe , Mostafa Saleh , Petr Tesarik , Alexey Kardashevskiy , Dan Williams , Xu Yilun , linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , x86@kernel.org, Jiri Pirko , Michael Kelley Subject: [PATCH v6 03/20] dma-direct: use DMA_ATTR_CC_SHARED in alloc/free paths Date: Thu, 4 Jun 2026 14:09:42 +0530 Message-ID: <20260604083959.1265923-4-aneesh.kumar@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260604083959.1265923-1-aneesh.kumar@kernel.org> References: <20260604083959.1265923-1-aneesh.kumar@kernel.org> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Propagate force_dma_unencrypted() into DMA_ATTR_CC_SHARED in the dma-direct allocation path and use the attribute to drive the related decisions. This updates dma_direct_alloc(), dma_direct_free(), and dma_direct_alloc_pages() to fold the forced unencrypted case into attrs. Tested-by: Jiri Pirko Tested-by: Michael Kelley Tested-by: Mostafa Saleh Signed-off-by: Aneesh Kumar K.V (Arm) --- kernel/dma/direct.c | 53 +++++++++++++++++++++++++++++++++++++-------- 1 file changed, 44 insertions(+), 9 deletions(-) diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index a741c8a2ee66..90dc5057a0c0 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -193,16 +193,31 @@ void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) { bool remap = false, set_uncached = false; - bool mark_mem_decrypt = true; + bool mark_mem_decrypt = false; struct page *page; void *ret; + /* + * DMA_ATTR_CC_SHARED is not a caller-visible dma_alloc_*() + * attribute. The direct allocator uses it internally after it has + * decided that the backing pages must be shared/decrypted, so the + * rest of the allocation path can consistently select DMA addresses, + * choose compatible pools and restore encryption on free. + */ + if (attrs & DMA_ATTR_CC_SHARED) + return NULL; + + if (force_dma_unencrypted(dev)) { + attrs |= DMA_ATTR_CC_SHARED; + mark_mem_decrypt = true; + } + size = PAGE_ALIGN(size); if (attrs & DMA_ATTR_NO_WARN) gfp |= __GFP_NOWARN; - if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) && - !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) + if (((attrs & (DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_CC_SHARED)) == + DMA_ATTR_NO_KERNEL_MAPPING) && !is_swiotlb_for_alloc(dev)) return dma_direct_alloc_no_mapping(dev, size, dma_handle, gfp); if (!dev_is_dma_coherent(dev)) { @@ -236,7 +251,7 @@ void *dma_direct_alloc(struct device *dev, size_t size, * Remapping or decrypting memory may block, allocate the memory from * the atomic pools instead if we aren't allowed block. */ - if ((remap || force_dma_unencrypted(dev)) && + if ((remap || (attrs & DMA_ATTR_CC_SHARED)) && dma_direct_use_pool(dev, gfp)) return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp); @@ -312,12 +327,24 @@ void dma_direct_free(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs) { phys_addr_t phys; - bool mark_mem_encrypted = true; + bool mark_mem_encrypted = false; struct io_tlb_pool *swiotlb_pool; unsigned int page_order = get_order(size); - if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) && - !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) { + /* see dma_direct_alloc() for details */ + WARN_ON(attrs & DMA_ATTR_CC_SHARED); + + /* + * if the device had requested for an unencrypted buffer, + * convert it to encrypted on free + */ + if (force_dma_unencrypted(dev)) { + attrs |= DMA_ATTR_CC_SHARED; + mark_mem_encrypted = true; + } + + if (((attrs & (DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_CC_SHARED)) == + DMA_ATTR_NO_KERNEL_MAPPING) && !is_swiotlb_for_alloc(dev)) { /* cpu_addr is a struct page cookie, not a kernel address */ dma_free_contiguous(dev, cpu_addr, size); return; @@ -366,10 +393,14 @@ void dma_direct_free(struct device *dev, size_t size, struct page *dma_direct_alloc_pages(struct device *dev, size_t size, dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp) { + unsigned long attrs = 0; struct page *page; void *ret; - if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp)) + if (force_dma_unencrypted(dev)) + attrs |= DMA_ATTR_CC_SHARED; + + if ((attrs & DMA_ATTR_CC_SHARED) && dma_direct_use_pool(dev, gfp)) return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp); if (is_swiotlb_for_alloc(dev)) { @@ -403,7 +434,11 @@ void dma_direct_free_pages(struct device *dev, size_t size, phys_addr_t phys; void *vaddr = page_address(page); struct io_tlb_pool *swiotlb_pool; - bool mark_mem_encrypted = true; + /* + * if the device had requested for an unencrypted buffer, + * convert it to encrypted on free + */ + bool mark_mem_encrypted = force_dma_unencrypted(dev); /* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */ if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) && -- 2.43.0