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 3BD8FC433F5 for ; Thu, 4 Nov 2021 12:31:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C4F5610FC for ; Thu, 4 Nov 2021 12:31:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231182AbhKDMdm (ORCPT ); Thu, 4 Nov 2021 08:33:42 -0400 Received: from mailgw01.mediatek.com ([60.244.123.138]:49214 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S229809AbhKDMdl (ORCPT ); Thu, 4 Nov 2021 08:33:41 -0400 X-UUID: c651f2c855144886b83e0c995d128bea-20211104 X-UUID: c651f2c855144886b83e0c995d128bea-20211104 Received: from mtkmbs10n2.mediatek.inc [(172.21.101.183)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1029824007; Thu, 04 Nov 2021 20:31:01 +0800 Received: from mtkmbs10n1.mediatek.inc (172.21.101.34) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.3; Thu, 4 Nov 2021 20:31:00 +0800 Received: from mtksdccf07 (172.21.84.99) by mtkmbs10n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.15 via Frontend Transport; Thu, 4 Nov 2021 20:31:00 +0800 Message-ID: Subject: Re: [PATCH v2] dma-direct: improve DMA_ATTR_NO_KERNEL_MAPPING From: Walter Wu To: Ard Biesheuvel , Christoph Hellwig CC: Marek Szyprowski , Robin Murphy , Matthias Brugger , "Andrew Morton" , Linux IOMMU , Linux Kernel Mailing List , Linux ARM , wsd_upstream , Date: Thu, 4 Nov 2021 20:31:00 +0800 In-Reply-To: References: <20211104023221.16391-1-walter-zh.wu@mediatek.com> <20211104085336.GA24260@lst.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2021-11-04 at 09:57 +0100, Ard Biesheuvel wrote: > On Thu, 4 Nov 2021 at 09:53, Christoph Hellwig wrote: > > > > On Thu, Nov 04, 2021 at 10:32:21AM +0800, Walter Wu wrote: > > > diff --git a/include/linux/set_memory.h > > > b/include/linux/set_memory.h > > > index f36be5166c19..6c7d1683339c 100644 > > > --- a/include/linux/set_memory.h > > > +++ b/include/linux/set_memory.h > > > @@ -7,11 +7,16 @@ > > > > > > #ifdef CONFIG_ARCH_HAS_SET_MEMORY > > > #include > > > + > > > +#ifndef CONFIG_RODATA_FULL_DEFAULT_ENABLED > > > > This is an arm64-specific symbol, and one that only controls a > > default. I don't think it is suitable to key off stubs in common > > code. > > > > > +static inline int set_memory_valid(unsigned long addr, int > > > numpages, int enable) { return 0; } > > > > Pleae avoid overly long lines. > > > > > + if (IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED)) > > > { > > > + kaddr = (unsigned > > > long)phys_to_virt(dma_to_phys(dev, *dma_handle)); > > > > This can just use page_address. > > > > > + /* page remove kernel mapping for arm64 */ > > > + set_memory_valid(kaddr, size >> PAGE_SHIFT, > > > 0); > > > + } > > > > But more importantly: set_memory_valid only exists on arm64, this > > will break compile everywhere else. And this API is complete crap. > > Passing kernel virtual addresses as unsigned long just sucks, and > > passing an integer argument for valid/non-valid also is a horrible > > API. > > > > ... and as I pointed out before, you can still pass rodata=off on > arm64, and get the old behavior, in which case bad things will happen > if you try to use an API that expects to operate on page mappings > with > a 1 GB block mapping. > Thanks for your suggestion. > And you still haven't explained what the actual problem is: is this > about CPU speculation corrupting non-cache coherent inbound DMA? No corrupiton, only cpu read it, we hope to fix the behavior. Thanks. Walter 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 29945C433EF for ; Thu, 4 Nov 2021 12:31:14 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 D3EAC610FC for ; Thu, 4 Nov 2021 12:31:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org D3EAC610FC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 9B726817EB; Thu, 4 Nov 2021 12:31:13 +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 Q-is_qJhMySW; Thu, 4 Nov 2021 12:31:12 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp1.osuosl.org (Postfix) with ESMTPS id 61569817E4; Thu, 4 Nov 2021 12:31:12 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 47ABCC0019; Thu, 4 Nov 2021 12:31:12 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [IPv6:2605:bc80:3010::133]) by lists.linuxfoundation.org (Postfix) with ESMTP id BF918C000E for ; Thu, 4 Nov 2021 12:31:10 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 9B0AE403A9 for ; Thu, 4 Nov 2021 12:31:10 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 4i6V6zUzfl8R for ; Thu, 4 Nov 2021 12:31:05 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) by smtp2.osuosl.org (Postfix) with ESMTPS id 8845740015 for ; Thu, 4 Nov 2021 12:31:05 +0000 (UTC) X-UUID: c651f2c855144886b83e0c995d128bea-20211104 X-UUID: c651f2c855144886b83e0c995d128bea-20211104 Received: from mtkmbs10n2.mediatek.inc [(172.21.101.183)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1029824007; Thu, 04 Nov 2021 20:31:01 +0800 Received: from mtkmbs10n1.mediatek.inc (172.21.101.34) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.3; Thu, 4 Nov 2021 20:31:00 +0800 Received: from mtksdccf07 (172.21.84.99) by mtkmbs10n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.15 via Frontend Transport; Thu, 4 Nov 2021 20:31:00 +0800 Message-ID: Subject: Re: [PATCH v2] dma-direct: improve DMA_ATTR_NO_KERNEL_MAPPING From: Walter Wu To: Ard Biesheuvel , Christoph Hellwig Date: Thu, 4 Nov 2021 20:31:00 +0800 In-Reply-To: References: <20211104023221.16391-1-walter-zh.wu@mediatek.com> <20211104085336.GA24260@lst.de> X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 X-MTK: N Cc: wsd_upstream , Linux Kernel Mailing List , Linux IOMMU , linux-mediatek@lists.infradead.org, Matthias Brugger , Andrew Morton , Robin Murphy , Linux ARM 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" On Thu, 2021-11-04 at 09:57 +0100, Ard Biesheuvel wrote: > On Thu, 4 Nov 2021 at 09:53, Christoph Hellwig wrote: > > > > On Thu, Nov 04, 2021 at 10:32:21AM +0800, Walter Wu wrote: > > > diff --git a/include/linux/set_memory.h > > > b/include/linux/set_memory.h > > > index f36be5166c19..6c7d1683339c 100644 > > > --- a/include/linux/set_memory.h > > > +++ b/include/linux/set_memory.h > > > @@ -7,11 +7,16 @@ > > > > > > #ifdef CONFIG_ARCH_HAS_SET_MEMORY > > > #include > > > + > > > +#ifndef CONFIG_RODATA_FULL_DEFAULT_ENABLED > > > > This is an arm64-specific symbol, and one that only controls a > > default. I don't think it is suitable to key off stubs in common > > code. > > > > > +static inline int set_memory_valid(unsigned long addr, int > > > numpages, int enable) { return 0; } > > > > Pleae avoid overly long lines. > > > > > + if (IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED)) > > > { > > > + kaddr = (unsigned > > > long)phys_to_virt(dma_to_phys(dev, *dma_handle)); > > > > This can just use page_address. > > > > > + /* page remove kernel mapping for arm64 */ > > > + set_memory_valid(kaddr, size >> PAGE_SHIFT, > > > 0); > > > + } > > > > But more importantly: set_memory_valid only exists on arm64, this > > will break compile everywhere else. And this API is complete crap. > > Passing kernel virtual addresses as unsigned long just sucks, and > > passing an integer argument for valid/non-valid also is a horrible > > API. > > > > ... and as I pointed out before, you can still pass rodata=off on > arm64, and get the old behavior, in which case bad things will happen > if you try to use an API that expects to operate on page mappings > with > a 1 GB block mapping. > Thanks for your suggestion. > And you still haven't explained what the actual problem is: is this > about CPU speculation corrupting non-cache coherent inbound DMA? No corrupiton, only cpu read it, we hope to fix the behavior. Thanks. Walter _______________________________________________ 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 20167C433F5 for ; Thu, 4 Nov 2021 12:41:33 +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 1939261076 for ; Thu, 4 Nov 2021 12:41:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 1939261076 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com 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:MIME-Version:References:In-Reply-To: Date:CC:To:From:Subject:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=NgOalMYgec2O4PlN1JLjNOQfq4zY/aPOp3J36C0AvHE=; b=JUAKNc+AVCq9uR l/X8BrWHUsn8rUCfqcyDasVL5AAAaMy4qTtqFVtV6+HLha0GWwAC4+D6SxB64YfrZZgD7/lNTYljj Y0uWPa2TLpthm4ZNKVz9f6XjgRCSc9cVtRb1pyLwV+gq9g0kZlCWKjIMBfNm3R4IbVzk7+z1tzymt Tbd85mZBUbxeH3hMPTkd0KBsxWvbrxqCFs9yrK6UrS1VJ1oYufF80SaW/DXGchsaqST9OVbb8309g pf7E1g8ixWs1XR89oSAE0X5xdBRfHVW70LEmirUkRrPgDL30LFcSipawoM/vs9GD4FLzqgaBT3KUY mUFGjgX9kDOxNxdD0hug==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mic3V-008umF-IG; Thu, 04 Nov 2021 12:41:21 +0000 Received: from mailgw02.mediatek.com ([216.200.240.185]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mic3H-008uim-82; Thu, 04 Nov 2021 12:41:08 +0000 X-UUID: 37383a61037d4c43a1c02029824a61d5-20211104 X-UUID: 37383a61037d4c43a1c02029824a61d5-20211104 Received: from mtkcas66.mediatek.inc [(172.29.193.44)] by mailgw02.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 1077727830; Thu, 04 Nov 2021 05:41:03 -0700 Received: from mtkmbs10n2.mediatek.inc (172.21.101.183) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 4 Nov 2021 05:31:01 -0700 Received: from mtkmbs10n1.mediatek.inc (172.21.101.34) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.3; Thu, 4 Nov 2021 20:31:00 +0800 Received: from mtksdccf07 (172.21.84.99) by mtkmbs10n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.15 via Frontend Transport; Thu, 4 Nov 2021 20:31:00 +0800 Message-ID: Subject: Re: [PATCH v2] dma-direct: improve DMA_ATTR_NO_KERNEL_MAPPING From: Walter Wu To: Ard Biesheuvel , Christoph Hellwig CC: Marek Szyprowski , Robin Murphy , Matthias Brugger , "Andrew Morton" , Linux IOMMU , Linux Kernel Mailing List , Linux ARM , wsd_upstream , Date: Thu, 4 Nov 2021 20:31:00 +0800 In-Reply-To: References: <20211104023221.16391-1-walter-zh.wu@mediatek.com> <20211104085336.GA24260@lst.de> X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211104_054107_329725_3AA382BC X-CRM114-Status: GOOD ( 28.81 ) 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 On Thu, 2021-11-04 at 09:57 +0100, Ard Biesheuvel wrote: > On Thu, 4 Nov 2021 at 09:53, Christoph Hellwig wrote: > > > > On Thu, Nov 04, 2021 at 10:32:21AM +0800, Walter Wu wrote: > > > diff --git a/include/linux/set_memory.h > > > b/include/linux/set_memory.h > > > index f36be5166c19..6c7d1683339c 100644 > > > --- a/include/linux/set_memory.h > > > +++ b/include/linux/set_memory.h > > > @@ -7,11 +7,16 @@ > > > > > > #ifdef CONFIG_ARCH_HAS_SET_MEMORY > > > #include > > > + > > > +#ifndef CONFIG_RODATA_FULL_DEFAULT_ENABLED > > > > This is an arm64-specific symbol, and one that only controls a > > default. I don't think it is suitable to key off stubs in common > > code. > > > > > +static inline int set_memory_valid(unsigned long addr, int > > > numpages, int enable) { return 0; } > > > > Pleae avoid overly long lines. > > > > > + if (IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED)) > > > { > > > + kaddr = (unsigned > > > long)phys_to_virt(dma_to_phys(dev, *dma_handle)); > > > > This can just use page_address. > > > > > + /* page remove kernel mapping for arm64 */ > > > + set_memory_valid(kaddr, size >> PAGE_SHIFT, > > > 0); > > > + } > > > > But more importantly: set_memory_valid only exists on arm64, this > > will break compile everywhere else. And this API is complete crap. > > Passing kernel virtual addresses as unsigned long just sucks, and > > passing an integer argument for valid/non-valid also is a horrible > > API. > > > > ... and as I pointed out before, you can still pass rodata=off on > arm64, and get the old behavior, in which case bad things will happen > if you try to use an API that expects to operate on page mappings > with > a 1 GB block mapping. > Thanks for your suggestion. > And you still haven't explained what the actual problem is: is this > about CPU speculation corrupting non-cache coherent inbound DMA? No corrupiton, only cpu read it, we hope to fix the behavior. Thanks. Walter _______________________________________________ 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 D14DFC433F5 for ; Thu, 4 Nov 2021 12:42:25 +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 96D4D60EB8 for ; Thu, 4 Nov 2021 12:42:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 96D4D60EB8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com 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:MIME-Version:References:In-Reply-To: Date:CC:To:From:Subject:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=KtGaKgsFOVo4pDGHp4sy8JzB6k/HcqtLovGbadAAXXU=; b=wxa21AWe0XaaC/ lVrM1PU3Suq5ubdU9ysaOkOMXqsWq3dLBv2HOpUrNm3ImaVDPT6DW1Z37gdSp2VrV4I0ZwO9uQ1by FQIwDmUOFTUhU7Pmf0AqW3U9zkqsBwRbvtD0YCRfjeZTHAKOuK4NZXbtti3EZvPS66ztku/ZnwiMx VmxcIOYIQ17CIJhPWWAOyn6G+wH8xlqCBhl8X7dcA8MLuYXiCX8/fbZOekKNpBlAXlF6oBlWEY+hu QRnu9+PQkhbtInVEonEKjmF2iYPSUFc8fSTniRpS+oZRn1oUc9btQbsouuY9dVEsQw+kiKLuvue71 W5mtvrs2AQ92srs8fdDg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mic3L-008uk5-Q6; Thu, 04 Nov 2021 12:41:11 +0000 Received: from mailgw02.mediatek.com ([216.200.240.185]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mic3H-008uim-82; Thu, 04 Nov 2021 12:41:08 +0000 X-UUID: 37383a61037d4c43a1c02029824a61d5-20211104 X-UUID: 37383a61037d4c43a1c02029824a61d5-20211104 Received: from mtkcas66.mediatek.inc [(172.29.193.44)] by mailgw02.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 1077727830; Thu, 04 Nov 2021 05:41:03 -0700 Received: from mtkmbs10n2.mediatek.inc (172.21.101.183) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 4 Nov 2021 05:31:01 -0700 Received: from mtkmbs10n1.mediatek.inc (172.21.101.34) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.3; Thu, 4 Nov 2021 20:31:00 +0800 Received: from mtksdccf07 (172.21.84.99) by mtkmbs10n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.15 via Frontend Transport; Thu, 4 Nov 2021 20:31:00 +0800 Message-ID: Subject: Re: [PATCH v2] dma-direct: improve DMA_ATTR_NO_KERNEL_MAPPING From: Walter Wu To: Ard Biesheuvel , Christoph Hellwig CC: Marek Szyprowski , Robin Murphy , Matthias Brugger , "Andrew Morton" , Linux IOMMU , Linux Kernel Mailing List , Linux ARM , wsd_upstream , Date: Thu, 4 Nov 2021 20:31:00 +0800 In-Reply-To: References: <20211104023221.16391-1-walter-zh.wu@mediatek.com> <20211104085336.GA24260@lst.de> X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211104_054107_329725_3AA382BC X-CRM114-Status: GOOD ( 28.81 ) 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 On Thu, 2021-11-04 at 09:57 +0100, Ard Biesheuvel wrote: > On Thu, 4 Nov 2021 at 09:53, Christoph Hellwig wrote: > > > > On Thu, Nov 04, 2021 at 10:32:21AM +0800, Walter Wu wrote: > > > diff --git a/include/linux/set_memory.h > > > b/include/linux/set_memory.h > > > index f36be5166c19..6c7d1683339c 100644 > > > --- a/include/linux/set_memory.h > > > +++ b/include/linux/set_memory.h > > > @@ -7,11 +7,16 @@ > > > > > > #ifdef CONFIG_ARCH_HAS_SET_MEMORY > > > #include > > > + > > > +#ifndef CONFIG_RODATA_FULL_DEFAULT_ENABLED > > > > This is an arm64-specific symbol, and one that only controls a > > default. I don't think it is suitable to key off stubs in common > > code. > > > > > +static inline int set_memory_valid(unsigned long addr, int > > > numpages, int enable) { return 0; } > > > > Pleae avoid overly long lines. > > > > > + if (IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED)) > > > { > > > + kaddr = (unsigned > > > long)phys_to_virt(dma_to_phys(dev, *dma_handle)); > > > > This can just use page_address. > > > > > + /* page remove kernel mapping for arm64 */ > > > + set_memory_valid(kaddr, size >> PAGE_SHIFT, > > > 0); > > > + } > > > > But more importantly: set_memory_valid only exists on arm64, this > > will break compile everywhere else. And this API is complete crap. > > Passing kernel virtual addresses as unsigned long just sucks, and > > passing an integer argument for valid/non-valid also is a horrible > > API. > > > > ... and as I pointed out before, you can still pass rodata=off on > arm64, and get the old behavior, in which case bad things will happen > if you try to use an API that expects to operate on page mappings > with > a 1 GB block mapping. > Thanks for your suggestion. > And you still haven't explained what the actual problem is: is this > about CPU speculation corrupting non-cache coherent inbound DMA? No corrupiton, only cpu read it, we hope to fix the behavior. Thanks. Walter _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel