From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 0C96D3921F6; Wed, 1 Jul 2026 05:52:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782885173; cv=none; b=aNuDqf7EAdcFuYzDwlY7cDGJ7QwZsHD/dvai5KNBbBmPBi0MoAcrOvmwtVdBLw3K0Ny+8Vmho5UKwGohtqtL/gOyUmetXYUZ3wAMevnVV9lYYRn/cicmmfGXB5oCZD3w2PuOcOybB/bdv+dhWoUpgyI7f+ECNGhGA0tTYLOIN1I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782885173; c=relaxed/simple; bh=BtQEe3n7AqtQ19rvSk1NFYOfxuRFZUx2gOHkUNp1tBk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QuVEAU0L3K9LxRBc/ZGhqB8d88VpPlyHwgO6eKPS0jAh6N2MxmjzeSHnX1C4o982AIf+e3/nzeaoaosZUCXSHCqUe5TAZCRYlCieBXVVrxwbKokrukSm78GNngXn79r6qotY1erj6cQi+mivJRXKdnRh0w66MLTYapJGUR2YhUw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WVeKpmo7; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="WVeKpmo7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2CA871F00A3D; Wed, 1 Jul 2026 05:52:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782885171; bh=W0tJTJ305iRhSOCgOFoS2BFeM7HDCfqTXnANjOM7DSI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=WVeKpmo7fR0aEsUL690bZyKIq3jNSQBC9h8KfgOw7kPOX0SK65zq6NZzlFLzVrcfg 4MUUijLahbxQiij23Nm7SXjAqsmm1sIj/MBbRl1A8KwcfXXOCtOg4RNh10WwfqNNyr I2fcOwe3dGON2Bl4EdgasiBO9zJZ5JCFq9XPFpAYJXAV4FxkxcMLXidPaC6N/zceTI G1u/UymKTcrFI1IBQocAJWFWeZcUGZWL8kYOhxNFh35nQwfrIQHcL8LanyXGjRfw01 BlIH16bt/vFwzZo6ConX4AxpDRN+GIQPv2rryz/RUaBLSAYACepOm7qh3luxxotlap skHfFFwz36gVQ== 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 v7 17/22] dma-direct: set decrypted flag for remapped DMA allocations Date: Wed, 1 Jul 2026 11:19:21 +0530 Message-ID: <20260701054926.825925-18-aneesh.kumar@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260701054926.825925-1-aneesh.kumar@kernel.org> References: <20260701054926.825925-1-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 Devices that are DMA non-coherent and require a remap were skipping dma_set_decrypted(), leaving DMA buffers encrypted even when the device requires unencrypted access. Move the call after the if (remap) branch so that both the direct and remapped allocation paths correctly mark the allocation as decrypted (or fail cleanly) before use. Fix dma_direct_alloc() and dma_direct_free() to apply set_memory_*() to the linear-map alias of the backing pages instead of the remapped CPU address. Also disallow highmem pages for __DMA_ATTR_ALLOC_CC_SHARED, because highmem buffers do not provide a usable linear-map address. Tested-by: Jiri Pirko Tested-by: Michael Kelley Tested-by: Mostafa Saleh Signed-off-by: Aneesh Kumar K.V (Arm) --- kernel/dma/direct.c | 56 +++++++++++++++++++++++++++++++++++---------- 1 file changed, 44 insertions(+), 12 deletions(-) diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index edf40746a775..964e8b0d8709 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -196,14 +196,23 @@ void *dma_direct_alloc(struct device *dev, size_t size, { bool remap = false, set_uncached = false; bool mark_mem_decrypt = false; + bool allow_highmem = true; struct page *page; void *ret; if (force_dma_unencrypted(dev)) attrs |= __DMA_ATTR_ALLOC_CC_SHARED; - if (attrs & __DMA_ATTR_ALLOC_CC_SHARED) + if (attrs & __DMA_ATTR_ALLOC_CC_SHARED) { + /* + * Unencrypted/shared DMA requires a linear-mapped buffer + * address to look up the PFN and set architecture-required PFN + * attributes. This is not possible with HighMem. Avoid HighMem + * allocation. + */ + allow_highmem = false; mark_mem_decrypt = true; + } size = PAGE_ALIGN(size); if (attrs & DMA_ATTR_NO_WARN) @@ -265,7 +274,7 @@ void *dma_direct_alloc(struct device *dev, size_t size, } /* we always manually zero the memory once we are done */ - page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO, true); + page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO, allow_highmem); if (!page) return NULL; @@ -280,6 +289,14 @@ void *dma_direct_alloc(struct device *dev, size_t size, set_uncached = false; } + if (mark_mem_decrypt) { + void *lm_addr; + + lm_addr = page_address(page); + if (set_memory_decrypted((unsigned long)lm_addr, PFN_UP(size))) + goto out_leak_pages; + } + if (remap) { pgprot_t prot = dma_pgprot(dev, PAGE_KERNEL, attrs); @@ -290,29 +307,36 @@ void *dma_direct_alloc(struct device *dev, size_t size, ret = dma_common_contiguous_remap(page, size, prot, __builtin_return_address(0)); if (!ret) - goto out_free_pages; + goto out_encrypt_pages; } else { ret = page_address(page); - if (mark_mem_decrypt && dma_set_decrypted(dev, ret, size)) - goto out_leak_pages; } memset(ret, 0, size); if (set_uncached) { + void *uncached_cpu_addr; + arch_dma_prep_coherent(page, size); - ret = arch_dma_set_uncached(ret, size); - if (IS_ERR(ret)) - goto out_encrypt_pages; + uncached_cpu_addr = arch_dma_set_uncached(ret, size); + if (IS_ERR(uncached_cpu_addr)) + goto out_free_remap_pages; + ret = uncached_cpu_addr; } *dma_handle = phys_to_dma_direct(dev, page_to_phys(page)); return ret; + +out_free_remap_pages: + if (remap) + dma_common_free_remap(ret, size); + out_encrypt_pages: - if (mark_mem_decrypt && dma_set_encrypted(dev, page_address(page), size)) - return NULL; -out_free_pages: + if (mark_mem_decrypt && + dma_set_encrypted(dev, page_address(page), size)) + goto out_leak_pages; + if (!swiotlb_free(dev, page, size)) dma_free_contiguous(dev, page, size); return NULL; @@ -375,8 +399,16 @@ void dma_direct_free(struct device *dev, size_t size, } else { if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED)) arch_dma_clear_uncached(cpu_addr, size); - if (mark_mem_encrypted && dma_set_encrypted(dev, cpu_addr, size)) + } + + if (mark_mem_encrypted) { + void *lm_addr; + + lm_addr = phys_to_virt(phys); + if (set_memory_encrypted((unsigned long)lm_addr, PFN_UP(size))) { + pr_warn_ratelimited("leaking DMA memory that can't be re-encrypted\n"); return; + } } if (swiotlb_pool) -- 2.43.0