From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BEF26C433EF for ; Tue, 2 Nov 2021 06:42:05 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 14C7A60720 for ; Tue, 2 Nov 2021 06:42:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 14C7A60720 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id D0335402CB; Tue, 2 Nov 2021 06:42:04 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id MPzAh28YtzLq; Tue, 2 Nov 2021 06:42:04 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp4.osuosl.org (Postfix) with ESMTPS id AF1FC40125; Tue, 2 Nov 2021 06:42:03 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 68D8DC0019; Tue, 2 Nov 2021 06:42:03 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 32870C000E for ; Tue, 2 Nov 2021 06:42:02 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 2E96D80C4F for ; Tue, 2 Nov 2021 06:42:02 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JunLqXYxyPj8 for ; Tue, 2 Nov 2021 06:42:01 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by smtp1.osuosl.org (Postfix) with ESMTPS id DAB3B80C49 for ; Tue, 2 Nov 2021 06:42:00 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 7487768AA6; Tue, 2 Nov 2021 07:41:55 +0100 (CET) Date: Tue, 2 Nov 2021 07:41:55 +0100 From: Christoph Hellwig To: Walter Wu Subject: Re: [PATCH] dma-direct: fix DMA_ATTR_NO_KERNEL_MAPPING Message-ID: <20211102064155.GA27749@lst.de> References: <20211101031558.7184-1-walter-zh.wu@mediatek.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20211101031558.7184-1-walter-zh.wu@mediatek.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: wsd_upstream , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-mediatek@lists.infradead.org, Matthias Brugger , Andrew Morton , Robin Murphy , Christoph Hellwig , linux-arm-kernel@lists.infradead.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" As others pointed out, DMA_ATTR_NO_KERNEL_MAPPING just means the caller can't rely on a kernel mapping. So the "fix" here is wrong. That being said for cases where we can easily remove a page from the kernel mapping it would be nice to do to: a) improve security b) as a debug check to see that no one actually tries to access it > + /* remove kernel mapping for pages */ > + set_memory_valid((unsigned long)phys_to_virt(dma_to_phys(dev, *dma_handle)), Please avoid overly long lines. Also this function only exists for arm64 also and others pointed out won't work for all cases. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 81B06C433EF for ; Tue, 2 Nov 2021 06:42:23 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 30FF960E74 for ; Tue, 2 Nov 2021 06:42:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 30FF960E74 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Pl4ygMrr/K6PUViF4gS7YqXY4pTWViu48l74eWTp8XY=; b=z382pEKdzufaAK 9y69JgkUQNiuJW6Bm94objV9t5qrjN26GfC5JX9Ix9M2Zw+JxXZg1jFt922Efj0E6c4PLv98JlaCJ Iaw+NstsW3iSVqkqgPz0Nq1p+kKHePj/U/JhyUT4taCFXfUud2RD0rTRprXw8c/YyHy2C7tGuYThn iLcQqtIP1u/OxYnVV/9c6jWd4wLk0OpOCEd0IpdnsiJzkV1UaQ2pAodJHC6Zf5Fru83tSzZfmnojV vl6AryMq6HlYPHChU5Gp/RSkSVHXZ/T31nNoqmxURQO7tRCO9VYJQk3biym4nthxW7FQSCUKtpuM9 9DdYrdFK1+uyTgu3B2Iw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mhnUo-000fWi-SR; Tue, 02 Nov 2021 06:42:10 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mhnUc-000fTt-Ii; Tue, 02 Nov 2021 06:41:59 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 7487768AA6; Tue, 2 Nov 2021 07:41:55 +0100 (CET) Date: Tue, 2 Nov 2021 07:41:55 +0100 From: Christoph Hellwig To: Walter Wu Cc: Christoph Hellwig , Marek Szyprowski , Robin Murphy , Matthias Brugger , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, wsd_upstream , linux-mediatek@lists.infradead.org, Andrew Morton Subject: Re: [PATCH] dma-direct: fix DMA_ATTR_NO_KERNEL_MAPPING Message-ID: <20211102064155.GA27749@lst.de> References: <20211101031558.7184-1-walter-zh.wu@mediatek.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20211101031558.7184-1-walter-zh.wu@mediatek.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211101_234158_788290_B841E33F X-CRM114-Status: GOOD ( 13.62 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org As others pointed out, DMA_ATTR_NO_KERNEL_MAPPING just means the caller can't rely on a kernel mapping. So the "fix" here is wrong. That being said for cases where we can easily remove a page from the kernel mapping it would be nice to do to: a) improve security b) as a debug check to see that no one actually tries to access it > + /* remove kernel mapping for pages */ > + set_memory_valid((unsigned long)phys_to_virt(dma_to_phys(dev, *dma_handle)), Please avoid overly long lines. Also this function only exists for arm64 also and others pointed out won't work for all cases. _______________________________________________ Linux-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30E0EC433EF for ; Tue, 2 Nov 2021 06:43:10 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E918760E8C for ; Tue, 2 Nov 2021 06:43:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E918760E8C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=EIwEJwIeHnYidL8Jt0ptsjgLPV5UgWDqHDgGlrJjCmY=; b=cTshB94irYqDpV VhsB4BPrARi0Kqng0FfO4GYk6p6tlndW7/UplMJJUTbVvZN4145nbBeN07MkAzB1ZJ5dqeCWsPsfn vanGQ6hyejFw/s1xoekzKbWcJ20ZNixafs7AKGTuC76VeyG2a5rwBH2NOwk2V1hwOpdn/KgpxJnWc scT3gRWnEQz6pizUjnBcgcZRmoMWVMezCOIolOyLyC08ME7dhxgAtoPV6td350iFAPVMeCj3jeHje OrolNrJjTAlWfpNG5Ei/bmxcZIbq9EO/KtmCsNZll60McB+NUqr4tjS0/fA+k4QwGBCzLz5D/CvFU 4PP8fzmzA/Q1kIwcrBtg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mhnUg-000fUn-4I; Tue, 02 Nov 2021 06:42:02 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mhnUc-000fTt-Ii; Tue, 02 Nov 2021 06:41:59 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 7487768AA6; Tue, 2 Nov 2021 07:41:55 +0100 (CET) Date: Tue, 2 Nov 2021 07:41:55 +0100 From: Christoph Hellwig To: Walter Wu Cc: Christoph Hellwig , Marek Szyprowski , Robin Murphy , Matthias Brugger , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, wsd_upstream , linux-mediatek@lists.infradead.org, Andrew Morton Subject: Re: [PATCH] dma-direct: fix DMA_ATTR_NO_KERNEL_MAPPING Message-ID: <20211102064155.GA27749@lst.de> References: <20211101031558.7184-1-walter-zh.wu@mediatek.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20211101031558.7184-1-walter-zh.wu@mediatek.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211101_234158_788290_B841E33F X-CRM114-Status: GOOD ( 13.62 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org As others pointed out, DMA_ATTR_NO_KERNEL_MAPPING just means the caller can't rely on a kernel mapping. So the "fix" here is wrong. That being said for cases where we can easily remove a page from the kernel mapping it would be nice to do to: a) improve security b) as a debug check to see that no one actually tries to access it > + /* remove kernel mapping for pages */ > + set_memory_valid((unsigned long)phys_to_virt(dma_to_phys(dev, *dma_handle)), Please avoid overly long lines. Also this function only exists for arm64 also and others pointed out won't work for all cases. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6117C433EF for ; Tue, 2 Nov 2021 06:42:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A39160F02 for ; Tue, 2 Nov 2021 06:42:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229769AbhKBGoe (ORCPT ); Tue, 2 Nov 2021 02:44:34 -0400 Received: from verein.lst.de ([213.95.11.211]:54601 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229497AbhKBGoc (ORCPT ); Tue, 2 Nov 2021 02:44:32 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 7487768AA6; Tue, 2 Nov 2021 07:41:55 +0100 (CET) Date: Tue, 2 Nov 2021 07:41:55 +0100 From: Christoph Hellwig To: Walter Wu Cc: Christoph Hellwig , Marek Szyprowski , Robin Murphy , Matthias Brugger , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, wsd_upstream , linux-mediatek@lists.infradead.org, Andrew Morton Subject: Re: [PATCH] dma-direct: fix DMA_ATTR_NO_KERNEL_MAPPING Message-ID: <20211102064155.GA27749@lst.de> References: <20211101031558.7184-1-walter-zh.wu@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211101031558.7184-1-walter-zh.wu@mediatek.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As others pointed out, DMA_ATTR_NO_KERNEL_MAPPING just means the caller can't rely on a kernel mapping. So the "fix" here is wrong. That being said for cases where we can easily remove a page from the kernel mapping it would be nice to do to: a) improve security b) as a debug check to see that no one actually tries to access it > + /* remove kernel mapping for pages */ > + set_memory_valid((unsigned long)phys_to_virt(dma_to_phys(dev, *dma_handle)), Please avoid overly long lines. Also this function only exists for arm64 also and others pointed out won't work for all cases.