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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 162FAECE564 for ; Tue, 18 Sep 2018 18:52:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B518321508 for ; Tue, 18 Sep 2018 18:52:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B518321508 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729279AbeISA0D (ORCPT ); Tue, 18 Sep 2018 20:26:03 -0400 Received: from foss.arm.com ([217.140.101.70]:49500 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727140AbeISA0D (ORCPT ); Tue, 18 Sep 2018 20:26:03 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6CFDAED1; Tue, 18 Sep 2018 11:52:08 -0700 (PDT) Received: from [192.168.1.123] (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 449FC3F703; Tue, 18 Sep 2018 11:52:05 -0700 (PDT) Subject: Re: [PATCH v7 2/6] iommu/dma: Add support for non-strict mode To: Will Deacon Cc: joro@8bytes.org, thunder.leizhen@huawei.com, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linuxarm@huawei.com, guohanjun@huawei.com, huawei.libin@huawei.com, john.garry@huawei.com References: <0a891cec4bb164f8cf2f57c753791a7d1f5f1d81.1536935328.git.robin.murphy@arm.com> <20180918171007.GJ16498@arm.com> From: Robin Murphy Message-ID: <60410578-64f3-9bb3-0b88-27cde93335d0@arm.com> Date: Tue, 18 Sep 2018 19:52:04 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180918171007.GJ16498@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-09-18 6:10 PM, Will Deacon wrote: > Hi Robin, > > On Fri, Sep 14, 2018 at 03:30:20PM +0100, Robin Murphy wrote: >> From: Zhen Lei >> >> 1. Save the related domain pointer in struct iommu_dma_cookie, make iovad >> capable call domain->ops->flush_iotlb_all to flush TLB. >> 2. During the iommu domain initialization phase, base on domain->non_strict >> field to check whether non-strict mode is supported or not. If so, call >> init_iova_flush_queue to register iovad->flush_cb callback. >> 3. All unmap(contains iova-free) APIs will finally invoke __iommu_dma_unmap >> -->iommu_dma_free_iova. If the domain is non-strict, call queue_iova to >> put off iova freeing, and omit iommu_tlb_sync operation. > > Hmm, this is basically just a commentary on the code. Please could you write > it more in terms of the problem that's being solved? Sure - I intentionally kept a light touch when it came to the documentation and commit messages in this rework (other than patch #1 where I eventually remembered the original reasoning and that it wasn't a bug). If we're more-or-less happy with the shape of the technical side I'll make sure to take a final pass through v8 to tidy up all the prose. >> Signed-off-by: Zhen Lei >> [rm: convert raw boolean to domain attribute] >> Signed-off-by: Robin Murphy >> --- >> drivers/iommu/dma-iommu.c | 29 ++++++++++++++++++++++++++++- >> include/linux/iommu.h | 1 + >> 2 files changed, 29 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c >> index 511ff9a1d6d9..092e6926dc3c 100644 >> --- a/drivers/iommu/dma-iommu.c >> +++ b/drivers/iommu/dma-iommu.c >> @@ -55,6 +55,9 @@ struct iommu_dma_cookie { >> }; >> struct list_head msi_page_list; >> spinlock_t msi_lock; >> + >> + /* Only be assigned in non-strict mode, otherwise it's NULL */ >> + struct iommu_domain *domain; >> }; >> >> static inline size_t cookie_msi_granule(struct iommu_dma_cookie *cookie) >> @@ -257,6 +260,17 @@ static int iova_reserve_iommu_regions(struct device *dev, >> return ret; >> } >> >> +static void iommu_dma_flush_iotlb_all(struct iova_domain *iovad) >> +{ >> + struct iommu_dma_cookie *cookie; >> + struct iommu_domain *domain; >> + >> + cookie = container_of(iovad, struct iommu_dma_cookie, iovad); >> + domain = cookie->domain; >> + >> + domain->ops->flush_iotlb_all(domain); > > Can we rely on this function pointer being non-NULL? I think it would > be better to call iommu_flush_tlb_all(cookie->domain) instead. Yeah, that's deliberate - in fact got as far as writing that change, then undid it as I realised that although the attribute conversion got rid of the explicit ops->flush_iotlb_all check, it still makes zero sense for an IOMMU driver to claim to support the flush queue attribute without also providing the relevant callback, so I do actually want this to blow up rather than silently do nothing if that assumption isn't met. >> +} >> + >> /** >> * iommu_dma_init_domain - Initialise a DMA mapping domain >> * @domain: IOMMU domain previously prepared by iommu_get_dma_cookie() >> @@ -275,6 +289,7 @@ int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base, >> struct iommu_dma_cookie *cookie = domain->iova_cookie; >> struct iova_domain *iovad = &cookie->iovad; >> unsigned long order, base_pfn, end_pfn; >> + int attr = 1; > > Do we actually need to initialise this? Oops, no, that's a left-over from the turned-out-messier-that-I-thought v6 implementation. Thanks, Robin.