From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DB5D835F8A8; Fri, 17 Apr 2026 08:59:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776416389; cv=none; b=hk1jhx1hlBEEa0Cs5avHdnwQjhV4y3Tg2NvosLejhxFbqAHjV8iZl9xMM9D2AGt7WETWqKeNkoB2+qT/oM4xhFKRDg8C7rdig9nBGLSqYvU8qhcwGAtTi/THt7dL9QNzmhre0ckoY6Ho1C9uPwyAjqkJIRZ2IhsSS64Row5yu2U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776416389; c=relaxed/simple; bh=SMTPZxBrGWET40HHUPAfjE8Aok3FvJ1waxDLjxRSjT4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JkPjiTbfgkN0M7vadzDZJEZX4LNxdWYLmM8tQiM28wb9jZ9H3CcaOsfHkYZTIDC5zp5XnvXo3knY05yCdSwfsQwWbifEFDBmcQSCGDWXYxL1j1y1zSMG10Dw/ovkbiv7wZhcKCrYOK12zAlyo5vREhoAh9QN0yqD8Z8mFQRnedU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RqGx5LZy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="RqGx5LZy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73FBCC19425; Fri, 17 Apr 2026 08:59:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776416389; bh=SMTPZxBrGWET40HHUPAfjE8Aok3FvJ1waxDLjxRSjT4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RqGx5LZy0P1djSqLPmUXT25WtLypdS74y16FcGTuMiPVXAiugQzw+25VmsigfPqVF tnG7LQ+e5e/ULL0JZJ4es5J+soRIsgLMQeo/hhbaGYSt1aArW8TvqGdSzcrcLoXLtP F6yAUOJnlphTjbnAaLS1Ra2+Zendlt7fSXp4PWTHr/CIVDad3Hq8LsvYMgcgdtTxvi /s83KE6gFVV7s7vutmgtkOeZjpyy2FEDI9AVrHD5aCDAMM2XxqBv0AGYzmtPomD4Rq lB1fDtdLzy/Z8HJVZsjl+Bq0HWfLMsg5E7u7PJoTHS7zLBrbqUjqL9arCWD+E1BTIf 6sl27qlyUQdFw== From: "Aneesh Kumar K.V (Arm)" To: iommu@lists.linux.dev, linux-kernel@vger.kernel.org Cc: robin.murphy@arm.com, m.szyprowski@samsung.com, will@kernel.org, maz@kernel.org, suzuki.poulose@arm.com, catalin.marinas@arm.com, jiri@resnulli.us, jgg@ziepe.ca, aneesh.kumar@kernel.org, Mostafa Saleh , Thomas Gleixner , Steven Price Subject: [RFC PATCH 1/7] dma-direct: swiotlb: handle swiotlb alloc/free outside __dma_direct_alloc_pages Date: Fri, 17 Apr 2026 14:28:54 +0530 Message-ID: <20260417085900.3062416-2-aneesh.kumar@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260417085900.3062416-1-aneesh.kumar@kernel.org> References: <20260417085900.3062416-1-aneesh.kumar@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Move swiotlb allocation out of __dma_direct_alloc_pages() and handle it in dma_direct_alloc() / dma_direct_alloc_pages(). This is needed for follow-up changes that align shared decrypted buffers to hypervisor page size. swiotlb pool memory is decrypted as a whole and does not need per-allocation alignment handling. swiotlb backing pages are already mapped decrypted by swiotlb_update_mem_attributes() and rmem_swiotlb_device_init(), so dma-direct should not call dma_set_decrypted() on allocation nor dma_set_encrypted() on free for swiotlb-backed memory. Update alloc/free paths to detect swiotlb-backed pages and skip encrypt/decrypt transitions for those paths. Keep the existing highmem rejection in dma_direct_alloc_pages() for swiotlb allocations. Only for "restricted-dma-pool", we currently set `for_alloc = true`, while rmem_swiotlb_device_init() decrypts the whole pool up front. This pool is typically used together with "shared-dma-pool", where the shared region is accessed after remap/ioremap and the returned address is suitable for decrypted memory access. So existing code paths remain valid. Cc: Marc Zyngier Cc: Thomas Gleixner Cc: Catalin Marinas Cc: Will Deacon Cc: Jason Gunthorpe Cc: Marek Szyprowski Cc: Robin Murphy Cc: Steven Price Cc: Suzuki K Poulose Signed-off-by: Aneesh Kumar K.V (Arm) --- kernel/dma/direct.c | 44 +++++++++++++++++++++++++++++++++++++------- 1 file changed, 37 insertions(+), 7 deletions(-) diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 8f43a930716d..c2a43e4ef902 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -125,9 +125,6 @@ static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size, WARN_ON_ONCE(!PAGE_ALIGNED(size)); - if (is_swiotlb_for_alloc(dev)) - return dma_direct_alloc_swiotlb(dev, size); - gfp |= dma_direct_optimal_gfp_mask(dev, &phys_limit); page = dma_alloc_contiguous(dev, size, gfp); if (page) { @@ -204,6 +201,7 @@ 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; struct page *page; void *ret; @@ -250,11 +248,21 @@ void *dma_direct_alloc(struct device *dev, size_t size, dma_direct_use_pool(dev, gfp)) return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp); + if (is_swiotlb_for_alloc(dev)) { + page = dma_direct_alloc_swiotlb(dev, size); + if (page) { + mark_mem_decrypt = false; + goto setup_page; + } + return NULL; + } + /* we always manually zero the memory once we are done */ page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO, true); if (!page) return NULL; +setup_page: /* * dma_alloc_contiguous can return highmem pages depending on a * combination the cma= arguments and per-arch setup. These need to be @@ -281,7 +289,7 @@ void *dma_direct_alloc(struct device *dev, size_t size, goto out_free_pages; } else { ret = page_address(page); - if (dma_set_decrypted(dev, ret, size)) + if (mark_mem_decrypt && dma_set_decrypted(dev, ret, size)) goto out_leak_pages; } @@ -298,7 +306,7 @@ void *dma_direct_alloc(struct device *dev, size_t size, return ret; out_encrypt_pages: - if (dma_set_encrypted(dev, page_address(page), size)) + if (mark_mem_decrypt && dma_set_encrypted(dev, page_address(page), size)) return NULL; out_free_pages: __dma_direct_free_pages(dev, page, size); @@ -310,6 +318,7 @@ void *dma_direct_alloc(struct device *dev, size_t size, void dma_direct_free(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs) { + bool mark_mem_encrypted = true; unsigned int page_order = get_order(size); if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) && @@ -338,12 +347,15 @@ void dma_direct_free(struct device *dev, size_t size, dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size))) return; + if (swiotlb_find_pool(dev, dma_to_phys(dev, dma_addr))) + mark_mem_encrypted = false; + if (is_vmalloc_addr(cpu_addr)) { vunmap(cpu_addr); } else { if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED)) arch_dma_clear_uncached(cpu_addr, size); - if (dma_set_encrypted(dev, cpu_addr, size)) + if (mark_mem_encrypted && dma_set_encrypted(dev, cpu_addr, size)) return; } @@ -359,6 +371,19 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size, if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp)) return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp); + if (is_swiotlb_for_alloc(dev)) { + page = dma_direct_alloc_swiotlb(dev, size); + if (!page) + return NULL; + + if (PageHighMem(page)) { + swiotlb_free(dev, page, size); + return NULL; + } + ret = page_address(page); + goto setup_page; + } + page = __dma_direct_alloc_pages(dev, size, gfp, false); if (!page) return NULL; @@ -366,6 +391,7 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size, ret = page_address(page); if (dma_set_decrypted(dev, ret, size)) goto out_leak_pages; +setup_page: memset(ret, 0, size); *dma_handle = phys_to_dma_direct(dev, page_to_phys(page)); return page; @@ -378,13 +404,17 @@ void dma_direct_free_pages(struct device *dev, size_t size, enum dma_data_direction dir) { void *vaddr = page_address(page); + bool mark_mem_encrypted = true; /* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */ if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) && dma_free_from_pool(dev, vaddr, size)) return; - if (dma_set_encrypted(dev, vaddr, size)) + if (swiotlb_find_pool(dev, page_to_phys(page))) + mark_mem_encrypted = false; + + if (mark_mem_encrypted && dma_set_encrypted(dev, vaddr, size)) return; __dma_direct_free_pages(dev, page, size); } -- 2.43.0