From nobody Sat Feb 7 11:31:23 2026 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 07F2D79DBA; Wed, 31 Jan 2024 12:25:51 +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=1706703952; cv=none; b=cGRXI6zRBWXsVCkBZB0zySy8bxm8Ny72wGyVEDuu65s52F7PtZ+UMGP8Lokzwlr9BGV0fJNcFWrAHYJnbUYIESO0MpM6nrlipZnt2eIdkM3J4TeoTpj6l1zoDO7OkW+WmD2F7wPiQs8I6D6qTmimo+/S2efCLLc2PQtjT0jMU24= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706703952; c=relaxed/simple; bh=yyPp81tTf7X1CFkP3aY3Bslp8DRgVUi3y++5NTa6UTU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=g7DhPPY+5ieeW0KwWr4BTCajUnV2zg/uIqZrquCwQlo39UpeqWPw8s52gePfFQ9bipu1TkHBc6wcpYpShOOIuZrjhfacoaHtc0e41g0xrtwZruy1IAwk7HJbnk0qlKaRiMj2fFwi7GfpuoE30wc82YHsznmF8Vkqds2CtbR2nSU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iRH0iXMC; 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="iRH0iXMC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B0BCFC433F1; Wed, 31 Jan 2024 12:25:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706703951; bh=yyPp81tTf7X1CFkP3aY3Bslp8DRgVUi3y++5NTa6UTU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iRH0iXMCF3ie/3WBc/jRy4rV4aMO/tXFNnTpH/R5DMvfiBaeAQratSSQGCe8Df6+C M4JoydOdj2t8+CZcYjwBHqxnEgkyQa9yTwdEd5zTCqF7OxEjlPPjhWIa/o+j1hWqpQ yyGmOAxqSenA2C47D/4WCx/fxUyoFKGuSz1bLU/po6nzdHwxjIFyQLx2aV88zeMCxN Gs1KgeGklRlRKDZgYFZ/I+H63WzuNMqkYBZmLmbnjQqKcHiiHE+ZWQE4dc7zTSd+wV WwzjpbBeV0SwWb0OCWUzKf9NJr8GoJipuIkUcjcqJ4UQSCL06JQ+3iJMbTrjSx6mRg atfmXhnvMaBsw== From: Will Deacon To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, Will Deacon , iommu@lists.linux.dev, Christoph Hellwig , Marek Szyprowski , Robin Murphy , Petr Tesarik , Dexuan Cui Subject: [PATCH v2 1/3] swiotlb: Fix allocation alignment requirement when searching slots Date: Wed, 31 Jan 2024 12:25:41 +0000 Message-Id: <20240131122543.14791-2-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20240131122543.14791-1-will@kernel.org> References: <20240131122543.14791-1-will@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: quoted-printable Content-Type: text/plain; charset="utf-8" Commit bbb73a103fbb ("swiotlb: fix a braino in the alignment check fix"), which was a fix for commit 0eee5ae10256 ("swiotlb: fix slot alignment checks"), causes a functional regression with vsock in a virtual machine using bouncing via a restricted DMA SWIOTLB pool. When virtio allocates the virtqueues for the vsock device using dma_alloc_coherent(), the SWIOTLB search fails to take into account the 8KiB buffer size and returns page-unaligned allocations if 'area->index' was left unaligned by a previous allocation from the buffer: # Final address in brackets is the SWIOTLB address returned to the caller | virtio-pci 0000:00:07.0: orig_addr 0x0 alloc_size 0x2000, iotlb_align_ma= sk 0x800 stride 0x2: got slot 1645-1649/7168 (0x98326800) | virtio-pci 0000:00:07.0: orig_addr 0x0 alloc_size 0x2000, iotlb_align_ma= sk 0x800 stride 0x2: got slot 1649-1653/7168 (0x98328800) | virtio-pci 0000:00:07.0: orig_addr 0x0 alloc_size 0x2000, iotlb_align_ma= sk 0x800 stride 0x2: got slot 1653-1657/7168 (0x9832a800) This ends in tears (typically buffer corruption and/or a hang) because swiotlb_alloc() blindly returns a pointer to the 'struct page' corresponding to the allocation and therefore the first half of the page ends up being allocated twice. Fix the problem by treating the allocation alignment separately to any additional alignment requirements from the device, using the maximum of the two as the stride to search the buffer slots. Fixes: bbb73a103fbb ("swiotlb: fix a braino in the alignment check fix") Fixes: 0eee5ae10256 ("swiotlb: fix slot alignment checks") Cc: Christoph Hellwig Cc: Marek Szyprowski Cc: Robin Murphy Cc: Petr Tesarik Cc: Dexuan Cui Signed-off-by: Will Deacon --- kernel/dma/swiotlb.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index b079a9a8e087..56cc08b1fbd6 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -982,7 +982,7 @@ static int swiotlb_search_pool_area(struct device *dev,= struct io_tlb_pool *pool phys_to_dma_unencrypted(dev, pool->start) & boundary_mask; unsigned long max_slots =3D get_max_slots(boundary_mask); unsigned int iotlb_align_mask =3D - dma_get_min_align_mask(dev) | alloc_align_mask; + dma_get_min_align_mask(dev) & ~(IO_TLB_SIZE - 1); unsigned int nslots =3D nr_slots(alloc_size), stride; unsigned int offset =3D swiotlb_align_offset(dev, orig_addr); unsigned int index, slots_checked, count =3D 0, i; @@ -993,19 +993,18 @@ static int swiotlb_search_pool_area(struct device *de= v, struct io_tlb_pool *pool BUG_ON(!nslots); BUG_ON(area_index >=3D pool->nareas); =20 + /* + * For mappings with an alignment requirement don't bother looping to + * unaligned slots once we found an aligned one. + */ + stride =3D get_max_slots(max(alloc_align_mask, iotlb_align_mask)); + /* * For allocations of PAGE_SIZE or larger only look for page aligned * allocations. */ if (alloc_size >=3D PAGE_SIZE) - iotlb_align_mask |=3D ~PAGE_MASK; - iotlb_align_mask &=3D ~(IO_TLB_SIZE - 1); - - /* - * For mappings with an alignment requirement don't bother looping to - * unaligned slots once we found an aligned one. - */ - stride =3D (iotlb_align_mask >> IO_TLB_SHIFT) + 1; + stride =3D max(stride, PAGE_SHIFT - IO_TLB_SHIFT + 1); =20 spin_lock_irqsave(&area->lock, flags); if (unlikely(nslots > pool->area_nslabs - area->used)) @@ -1015,14 +1014,16 @@ static int swiotlb_search_pool_area(struct device *= dev, struct io_tlb_pool *pool index =3D area->index; =20 for (slots_checked =3D 0; slots_checked < pool->area_nslabs; ) { - slot_index =3D slot_base + index; + phys_addr_t tlb_addr; =20 - if (orig_addr && - (slot_addr(tbl_dma_addr, slot_index) & - iotlb_align_mask) !=3D (orig_addr & iotlb_align_mask)) { + slot_index =3D slot_base + index; + tlb_addr =3D slot_addr(tbl_dma_addr, slot_index); + + if ((tlb_addr & alloc_align_mask) || + (orig_addr && (tlb_addr & iotlb_align_mask) !=3D + (orig_addr & iotlb_align_mask))) { index =3D wrap_area_index(pool, index + 1); slots_checked++; - continue; } =20 if (!iommu_is_span_boundary(slot_index, nslots, --=20 2.43.0.429.g432eaa2c6b-goog From nobody Sat Feb 7 11:31:23 2026 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 250757AE43; Wed, 31 Jan 2024 12:25:53 +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=1706703954; cv=none; b=oYlFCJIPrL/AiPggh29n6+X8ZcJmx3RhANmp5uRX9RLXQuWPhx8le0Q9Hde7HiF4AGhhktjj1Gi3PLrNsQaFPY8CsNbn5HZOF6JNrOa3Bh5bzxnlwZuN2yUGPqoLyVXSQV6ikf3JeB3UfAezpO05X9oW38x31o5etlmjOjCRChI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706703954; c=relaxed/simple; bh=tvZfP5ZDpz93rBnkWzn8NpisHuCrYWdGw0rDfTGSi0w=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=WBCC5JC6QIQ4WZkaYHAfzdB49yS88jDXXkjjrb2kSScPCdP0RuRz/LkLNXHGEibV6IDwZ04VnHCq+K/UbtrB5vuaio+pu4SxOJCh1bikLym/Q2wAzGLOaz+SQs/Fwvc0d3ut0BvkmM00TP4idac45nc0j14rP9p9keb7W0X4E2U= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=psoPX5uw; 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="psoPX5uw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF82CC43399; Wed, 31 Jan 2024 12:25:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706703953; bh=tvZfP5ZDpz93rBnkWzn8NpisHuCrYWdGw0rDfTGSi0w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=psoPX5uw05sqXOPDqQR+NcDpcVMXHTxr+ToULGVDXA91pOO4sDKAW6xGUtj1rRygW D1EtgsNsBW9z5MOfJUcBMMPzBLOjsRe5XTga8bzLOa9b4zvWWAc2G2Q2iTA5t4xNLl KtKJroPbgWfp2SuaPIwX5pRBEAo2p5SdfaIqjyriutK+J0vITqUdA8IevRtxbZ7C04 OzPdkiEMEfkJhGuV3ncoGiA+2hyHBoPDwsAJF/MLOQHkHbTppxE4W+zQfG4r1Zm9El u4b0V5kMmLRzZWIqNX2v763gsFq1lQNl7pyDMsvD0ODRbE5iBJ23OxIZf3HL5EqGZG v8VuNBl1Xzb+w== From: Will Deacon To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, Will Deacon , iommu@lists.linux.dev, Christoph Hellwig , Marek Szyprowski , Robin Murphy , Petr Tesarik , Dexuan Cui Subject: [PATCH v2 2/3] swiotlb: Enforce page alignment in swiotlb_alloc() Date: Wed, 31 Jan 2024 12:25:42 +0000 Message-Id: <20240131122543.14791-3-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20240131122543.14791-1-will@kernel.org> References: <20240131122543.14791-1-will@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: quoted-printable Content-Type: text/plain; charset="utf-8" When allocating pages from a restricted DMA pool in swiotlb_alloc(), the buffer address is blindly converted to a 'struct page *' that is returned to the caller. In the unlikely event of an allocation bug, page-unaligned addresses are not detected and slots can silently be double-allocated. Add a simple check of the buffer alignment in swiotlb_alloc() to make debugging a little easier if something has gone wonky. Cc: Christoph Hellwig Cc: Marek Szyprowski Cc: Robin Murphy Cc: Petr Tesarik Cc: Dexuan Cui Signed-off-by: Will Deacon --- kernel/dma/swiotlb.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 56cc08b1fbd6..4485f216e620 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -1642,6 +1642,12 @@ struct page *swiotlb_alloc(struct device *dev, size_= t size) return NULL; =20 tlb_addr =3D slot_addr(pool->start, index); + if (unlikely(!PAGE_ALIGNED(tlb_addr))) { + dev_WARN_ONCE(dev, 1, "Cannot allocate pages from non page-aligned swiot= lb addr 0x%pa.\n", + &tlb_addr); + swiotlb_release_slots(dev, tlb_addr); + return NULL; + } =20 return pfn_to_page(PFN_DOWN(tlb_addr)); } --=20 2.43.0.429.g432eaa2c6b-goog From nobody Sat Feb 7 11:31:23 2026 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 8891479938; Wed, 31 Jan 2024 12:25:56 +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=1706703956; cv=none; b=phvaHaEcwLKqBV2fiNoGuOD/ucxEQvoY0bd+Xy23s5ZZ64kfb2y2C/ODJBwmEDlyjAw59+ezHOsO1YuwIa2ocu2mVgmeSqAwBsuecNLLAeWLmV+AfPCbjnHGW5hUWIeOnqZakIQNyARAGkx8R9qcC60VaD/4DTOVOOh+AAAwAXE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706703956; c=relaxed/simple; bh=97FSX4oU5s9ZlUZoIaV1rFcSltgv+fl+Z/Ia3ZsihrQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=jdgpoiukA4FV2jxJ4idtvsyjbiE5U9LLtO5VxEEPlNbG0ecZljKTvoEjT51/r27YjA8Q4j7oOxXVSqzJC1soqCnrnaOPm1d6VWkfWY4+Ha035OXis+IdrEVNepm27wmE/c3RWPEX/a/Lb8mSGoElS4W7AR+6ty9yNtKWv8LYFTg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PS8Lt+3J; 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="PS8Lt+3J" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3AAD9C43390; Wed, 31 Jan 2024 12:25:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706703956; bh=97FSX4oU5s9ZlUZoIaV1rFcSltgv+fl+Z/Ia3ZsihrQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PS8Lt+3J3Xs0kHh+rJD0hfTP0DSeJUPH7CN4ilOfxfaxEBTtABTQKFhU1Vt6Fpl2h SXSdHDwsTGoxoDqLkFJctSVVpGe6bcg8D+ruZJSMQ9FtOZvbd2j6ArIUmJTydEP6Vq EtyOYy0RIbZaKV+hZb32fZ/s5BBWwSM3KYRey7qNdeHvVKj0KOC2C77zkelgMAGfM6 f1BcJFsEuDj8878ZiNGUZ8oz51mPpdupW5+NYpRewfsMIkoqZRWfkwondppd3ymkBO vNd4nflHvdfxun1SphQ32VxWLLgyY6a49tQ2rU989y6BJ5OHpugMz8mm/PWTuiVa8W nJvTjeNIafLhA== From: Will Deacon To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, Will Deacon , iommu@lists.linux.dev, Christoph Hellwig , Marek Szyprowski , Robin Murphy , Petr Tesarik , Dexuan Cui Subject: [PATCH v2 3/3] swiotlb: Honour dma_alloc_coherent() alignment in swiotlb_alloc() Date: Wed, 31 Jan 2024 12:25:43 +0000 Message-Id: <20240131122543.14791-4-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20240131122543.14791-1-will@kernel.org> References: <20240131122543.14791-1-will@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: quoted-printable Content-Type: text/plain; charset="utf-8" core-api/dma-api-howto.rst states the following properties of dma_alloc_coherent(): | The CPU virtual address and the DMA address are both guaranteed to | be aligned to the smallest PAGE_SIZE order which is greater than or | equal to the requested size. However, swiotlb_alloc() passes zero for the 'alloc_align_mask' parameter of swiotlb_find_slots() and so this property is not upheld. Instead, allocations larger than a page are aligned to PAGE_SIZE, Calculate the mask corresponding to the page order suitable for holding the allocation and pass that to swiotlb_find_slots(). Cc: Christoph Hellwig Cc: Marek Szyprowski Cc: Robin Murphy Cc: Petr Tesarik Cc: Dexuan Cui Signed-off-by: Will Deacon --- kernel/dma/swiotlb.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 4485f216e620..8ec37006ac70 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -1632,12 +1632,14 @@ struct page *swiotlb_alloc(struct device *dev, size= _t size) struct io_tlb_mem *mem =3D dev->dma_io_tlb_mem; struct io_tlb_pool *pool; phys_addr_t tlb_addr; + unsigned int align; int index; =20 if (!mem) return NULL; =20 - index =3D swiotlb_find_slots(dev, 0, size, 0, &pool); + align =3D (1 << (get_order(size) + PAGE_SHIFT)) - 1; + index =3D swiotlb_find_slots(dev, 0, size, align, &pool); if (index =3D=3D -1) return NULL; =20 --=20 2.43.0.429.g432eaa2c6b-goog