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[2604:1380:45e3:2400::1]) by mx.google.com with ESMTPS id t26-20020a056a00139a00b006dbdda40004si9712373pfg.108.2024.01.31.04.26.32 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 31 Jan 2024 04:26:32 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-46416-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=iRH0iXMC; arc=pass (i=1 dkim=pass dkdomain=kernel.org); spf=pass (google.com: domain of linux-kernel+bounces-46416-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-46416-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sv.mirrors.kernel.org (Postfix) with ESMTPS id 8E502294905 for ; Wed, 31 Jan 2024 12:26:32 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CF33D79DD9; Wed, 31 Jan 2024 12:25:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="iRH0iXMC" 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 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 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1789608845732583577 X-GMAIL-MSGID: 1789608845732583577 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_mask 0x800 stride 0x2: got slot 1645-1649/7168 (0x98326800) | virtio-pci 0000:00:07.0: orig_addr 0x0 alloc_size 0x2000, iotlb_align_mask 0x800 stride 0x2: got slot 1649-1653/7168 (0x98328800) | virtio-pci 0000:00:07.0: orig_addr 0x0 alloc_size 0x2000, iotlb_align_mask 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 = get_max_slots(boundary_mask); unsigned int iotlb_align_mask = - dma_get_min_align_mask(dev) | alloc_align_mask; + dma_get_min_align_mask(dev) & ~(IO_TLB_SIZE - 1); unsigned int nslots = nr_slots(alloc_size), stride; unsigned int offset = swiotlb_align_offset(dev, orig_addr); unsigned int index, slots_checked, count = 0, i; @@ -993,19 +993,18 @@ static int swiotlb_search_pool_area(struct device *dev, struct io_tlb_pool *pool BUG_ON(!nslots); BUG_ON(area_index >= pool->nareas); + /* + * For mappings with an alignment requirement don't bother looping to + * unaligned slots once we found an aligned one. + */ + stride = 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 >= PAGE_SIZE) - iotlb_align_mask |= ~PAGE_MASK; - iotlb_align_mask &= ~(IO_TLB_SIZE - 1); - - /* - * For mappings with an alignment requirement don't bother looping to - * unaligned slots once we found an aligned one. - */ - stride = (iotlb_align_mask >> IO_TLB_SHIFT) + 1; + stride = max(stride, PAGE_SHIFT - IO_TLB_SHIFT + 1); 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 = area->index; for (slots_checked = 0; slots_checked < pool->area_nslabs; ) { - slot_index = slot_base + index; + phys_addr_t tlb_addr; - if (orig_addr && - (slot_addr(tbl_dma_addr, slot_index) & - iotlb_align_mask) != (orig_addr & iotlb_align_mask)) { + slot_index = slot_base + index; + tlb_addr = slot_addr(tbl_dma_addr, slot_index); + + if ((tlb_addr & alloc_align_mask) || + (orig_addr && (tlb_addr & iotlb_align_mask) != + (orig_addr & iotlb_align_mask))) { index = wrap_area_index(pool, index + 1); slots_checked++; - continue; } if (!iommu_is_span_boundary(slot_index, nslots,