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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 4E745ECE587 for ; Mon, 14 Oct 2019 14:29:34 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 1F1222089C for ; Mon, 14 Oct 2019 14:29:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1F1222089C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 9201516B8; Mon, 14 Oct 2019 14:29:30 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 18C7814FD for ; Mon, 14 Oct 2019 14:21:19 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id 9E4C68A0 for ; Mon, 14 Oct 2019 14:21:17 +0000 (UTC) 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 2C8E2337; Mon, 14 Oct 2019 07:21:17 -0700 (PDT) Received: from [10.1.197.57] (e110467-lin.cambridge.arm.com [10.1.197.57]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0CB573F68E; Mon, 14 Oct 2019 07:21:14 -0700 (PDT) Subject: Re: [PATCH v3 3/7] iommu/mediatek: Use gather to achieve the tlb range flush To: Yong Wu , Matthias Brugger , Joerg Roedel , Will Deacon References: <1571035101-4213-1-git-send-email-yong.wu@mediatek.com> <1571035101-4213-4-git-send-email-yong.wu@mediatek.com> From: Robin Murphy Message-ID: Date: Mon, 14 Oct 2019 15:21:13 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <1571035101-4213-4-git-send-email-yong.wu@mediatek.com> Content-Language: en-GB Cc: youlin.pei@mediatek.com, anan.sun@mediatek.com, Nicolas Boichat , cui.zhang@mediatek.com, srv_heupstream@mediatek.com, chao.hao@mediatek.com, edison.hsieh@mediatek.com, linux-kernel@vger.kernel.org, Evan Green , Tomasz Figa , iommu@lists.linux-foundation.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On 14/10/2019 07:38, Yong Wu wrote: > Use the iommu_gather mechanism to achieve the tlb range flush. > Gather the iova range in the "tlb_add_page", then flush the merged iova > range in iotlb_sync. > > Note: If iotlb_sync comes from iommu_iotlb_gather_add_page, we have to > avoid retry the lock since the spinlock have already been acquired. I think this could probably be even simpler - once the actual register-poking is all confined to mtk_iommu_tlb_sync(), you should be able get rid of the per-domain locking in map/unmap and just have a single per-IOMMU lock to serialise syncs. The io-pgtable code itself hasn't needed external locking for a while now. Robin. > Suggested-by: Tomasz Figa > Signed-off-by: Yong Wu > --- > 1) This is the special case backtrace: > > mtk_iommu_iotlb_sync+0x50/0xa0 > mtk_iommu_tlb_flush_page_nosync+0x5c/0xd0 > __arm_v7s_unmap+0x174/0x598 > arm_v7s_unmap+0x30/0x48 > mtk_iommu_unmap+0x50/0x78 > __iommu_unmap+0xa4/0xf8 > > 2) The checking "if (gather->start == ULONG_MAX) return;" also is > necessary. It will happened when unmap only go to _flush_walk, then > enter this tlb_sync. > --- > drivers/iommu/mtk_iommu.c | 29 +++++++++++++++++++++++++---- > drivers/iommu/mtk_iommu.h | 1 + > 2 files changed, 26 insertions(+), 4 deletions(-) > > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c > index 5f594d6..8712afc 100644 > --- a/drivers/iommu/mtk_iommu.c > +++ b/drivers/iommu/mtk_iommu.c > @@ -234,7 +234,12 @@ static void mtk_iommu_tlb_flush_page_nosync(struct iommu_iotlb_gather *gather, > unsigned long iova, size_t granule, > void *cookie) > { > - mtk_iommu_tlb_add_flush_nosync(iova, granule, granule, true, cookie); > + struct mtk_iommu_data *data = cookie; > + struct iommu_domain *domain = &data->m4u_dom->domain; > + > + data->is_in_tlb_gather_add_page = true; > + iommu_iotlb_gather_add_page(domain, gather, iova, granule); > + data->is_in_tlb_gather_add_page = false; > } > > static const struct iommu_flush_ops mtk_iommu_flush_ops = { > @@ -453,12 +458,28 @@ static void mtk_iommu_flush_iotlb_all(struct iommu_domain *domain) > static void mtk_iommu_iotlb_sync(struct iommu_domain *domain, > struct iommu_iotlb_gather *gather) > { > + struct mtk_iommu_data *data = mtk_iommu_get_m4u_data(); > struct mtk_iommu_domain *dom = to_mtk_domain(domain); > + bool is_in_gather = data->is_in_tlb_gather_add_page; > + size_t length = gather->end - gather->start; > unsigned long flags; > > - spin_lock_irqsave(&dom->pgtlock, flags); > - mtk_iommu_tlb_sync(mtk_iommu_get_m4u_data()); > - spin_unlock_irqrestore(&dom->pgtlock, flags); > + if (gather->start == ULONG_MAX) > + return; > + > + /* > + * Avoid acquire the lock when it's in gather_add_page since the lock > + * has already been held. > + */ > + if (!is_in_gather) > + spin_lock_irqsave(&dom->pgtlock, flags); > + > + mtk_iommu_tlb_add_flush_nosync(gather->start, length, gather->pgsize, > + false, data); > + mtk_iommu_tlb_sync(data); > + > + if (!is_in_gather) > + spin_unlock_irqrestore(&dom->pgtlock, flags); > } > > static phys_addr_t mtk_iommu_iova_to_phys(struct iommu_domain *domain, > diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h > index fc0f16e..d29af1d 100644 > --- a/drivers/iommu/mtk_iommu.h > +++ b/drivers/iommu/mtk_iommu.h > @@ -58,6 +58,7 @@ struct mtk_iommu_data { > struct iommu_group *m4u_group; > bool enable_4GB; > bool tlb_flush_active; > + bool is_in_tlb_gather_add_page; > > struct iommu_device iommu; > const struct mtk_iommu_plat_data *plat_data; > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu