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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2DC2EC433C1 for ; Tue, 30 Mar 2021 13:20:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F047A61994 for ; Tue, 30 Mar 2021 13:20:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231803AbhC3NUN (ORCPT ); Tue, 30 Mar 2021 09:20:13 -0400 Received: from foss.arm.com ([217.140.110.172]:33462 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231622AbhC3NTp (ORCPT ); Tue, 30 Mar 2021 09:19:45 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5560C31B; Tue, 30 Mar 2021 06:19:45 -0700 (PDT) Received: from [10.57.27.121] (unknown [10.57.27.121]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F11D03F694; Tue, 30 Mar 2021 06:19:42 -0700 (PDT) Subject: Re: [PATCH 16/18] iommu: remove DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE To: Will Deacon , Christoph Hellwig Cc: Joerg Roedel , Li Yang , Michael Ellerman , David Woodhouse , Lu Baolu , linuxppc-dev@lists.ozlabs.org, linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org References: <20210316153825.135976-1-hch@lst.de> <20210316153825.135976-17-hch@lst.de> <20210330131149.GP5908@willie-the-truck> From: Robin Murphy Message-ID: Date: Tue, 30 Mar 2021 14:19:38 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <20210330131149.GP5908@willie-the-truck> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 2021-03-30 14:11, Will Deacon wrote: > On Tue, Mar 16, 2021 at 04:38:22PM +0100, Christoph Hellwig wrote: >> From: Robin Murphy >> >> Instead make the global iommu_dma_strict paramete in iommu.c canonical by >> exporting helpers to get and set it and use those directly in the drivers. >> >> This make sure that the iommu.strict parameter also works for the AMD and >> Intel IOMMU drivers on x86. As those default to lazy flushing a new >> IOMMU_CMD_LINE_STRICT is used to turn the value into a tristate to >> represent the default if not overriden by an explicit parameter. >> >> Signed-off-by: Robin Murphy . >> [ported on top of the other iommu_attr changes and added a few small >> missing bits] >> Signed-off-by: Christoph Hellwig >> --- >> drivers/iommu/amd/iommu.c | 23 +------- >> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 50 +--------------- >> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 1 - >> drivers/iommu/arm/arm-smmu/arm-smmu.c | 27 +-------- >> drivers/iommu/dma-iommu.c | 9 +-- >> drivers/iommu/intel/iommu.c | 64 ++++----------------- >> drivers/iommu/iommu.c | 27 ++++++--- >> include/linux/iommu.h | 4 +- >> 8 files changed, 40 insertions(+), 165 deletions(-) > > I really like this cleanup, but I can't help wonder if it's going in the > wrong direction. With SoCs often having multiple IOMMU instances and a > distinction between "trusted" and "untrusted" devices, then having the > flush-queue enabled on a per-IOMMU or per-domain basis doesn't sound > unreasonable to me, but this change makes it a global property. The intent here was just to streamline the existing behaviour of stuffing a global property into a domain attribute then pulling it out again in the illusion that it was in any way per-domain. We're still checking dev_is_untrusted() before making an actual decision, and it's not like we can't add more factors at that point if we want to. > For example, see the recent patch from Lu Baolu: > > https://lore.kernel.org/r/20210225061454.2864009-1-baolu.lu@linux.intel.com Erm, this patch is based on that one, it's right there in the context :/ Thanks, Robin.