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=-15.2 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 BCAB7C4338F for ; Mon, 2 Aug 2021 15:23:39 +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 591FF610A8 for ; Mon, 2 Aug 2021 15:23:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 591FF610A8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com 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 25293404F6; Mon, 2 Aug 2021 15:23:38 +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 2kubSa_I1m1X; Mon, 2 Aug 2021 15:23:37 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp4.osuosl.org (Postfix) with ESMTPS id 055214050A; Mon, 2 Aug 2021 15:23:37 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id DF178C0010; Mon, 2 Aug 2021 15:23:36 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 4E60CC000E for ; Mon, 2 Aug 2021 15:23:35 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 3DF674050A for ; Mon, 2 Aug 2021 15:23:35 +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 w33g5ngYmlnN for ; Mon, 2 Aug 2021 15:23:33 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by smtp4.osuosl.org (Postfix) with ESMTPS id 269B1404F6 for ; Mon, 2 Aug 2021 15:23:32 +0000 (UTC) Received: from fraeml741-chm.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4GdhbZ25Vcz6FFxN; Mon, 2 Aug 2021 23:23:22 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml741-chm.china.huawei.com (10.206.15.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Mon, 2 Aug 2021 17:23:29 +0200 Received: from [10.47.87.154] (10.47.87.154) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Mon, 2 Aug 2021 16:23:28 +0100 Subject: Re: [PATCH v4 2/6] iova: Allow rcache range upper limit to be flexible To: Will Deacon References: <1626259003-201303-1-git-send-email-john.garry@huawei.com> <1626259003-201303-3-git-send-email-john.garry@huawei.com> <20210802150153.GC28735@willie-the-truck> From: John Garry Message-ID: <27bb22cf-db64-0aa5-215f-2adf06b6455d@huawei.com> Date: Mon, 2 Aug 2021 16:23:00 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <20210802150153.GC28735@willie-the-truck> Content-Language: en-US X-Originating-IP: [10.47.87.154] X-ClientProxiedBy: lhreml713-chm.china.huawei.com (10.201.108.64) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Cc: linux-kernel@vger.kernel.org, sakari.ailus@linux.intel.com, mst@redhat.com, airlied@linux.ie, gregkh@linuxfoundation.org, linuxarm@huawei.com, jonathanh@nvidia.com, iommu@lists.linux-foundation.org, thierry.reding@gmail.com, daniel@ffwll.ch, bingbu.cao@intel.com, digetx@gmail.com, mchehab@kernel.org, robin.murphy@arm.com, jasowang@redhat.com, tian.shu.qiu@intel.com 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 02/08/2021 16:01, Will Deacon wrote: > On Wed, Jul 14, 2021 at 06:36:39PM +0800, John Garry wrote: >> Some LLDs may request DMA mappings whose IOVA length exceeds that of the >> current rcache upper limit. > > What's an LLD? > low-level driver maybe I'll stick with simply "drivers" >> This means that allocations for those IOVAs will never be cached, and >> always must be allocated and freed from the RB tree per DMA mapping cycle. >> This has a significant effect on performance, more so since commit >> 4e89dce72521 ("iommu/iova: Retry from last rb tree node if iova search >> fails"), as discussed at [0]. >> >> As a first step towards allowing the rcache range upper limit be >> configured, hold this value in the IOVA rcache structure, and allocate >> the rcaches separately. >> >> [0] https://lore.kernel.org/linux-iommu/20210129092120.1482-1-thunder.leizhen@huawei.com/ >> >> Signed-off-by: John Garry >> --- >> drivers/iommu/dma-iommu.c | 2 +- >> drivers/iommu/iova.c | 23 +++++++++++++++++------ >> include/linux/iova.h | 4 ++-- >> 3 files changed, 20 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c >> index 98ba927aee1a..4772278aa5da 100644 >> --- a/drivers/iommu/dma-iommu.c >> +++ b/drivers/iommu/dma-iommu.c >> @@ -434,7 +434,7 @@ static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain, >> * rounding up anything cacheable to make sure that can't happen. The >> * order of the unadjusted size will still match upon freeing. >> */ >> - if (iova_len < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1))) >> + if (iova_len < (1 << (iovad->rcache_max_size - 1))) >> iova_len = roundup_pow_of_two(iova_len); >> >> dma_limit = min_not_zero(dma_limit, dev->bus_dma_limit); >> diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c >> index b6cf5f16123b..07ce73fdd8c1 100644 >> --- a/drivers/iommu/iova.c >> +++ b/drivers/iommu/iova.c >> @@ -15,6 +15,8 @@ >> /* The anchor node sits above the top of the usable address space */ >> #define IOVA_ANCHOR ~0UL >> >> +#define IOVA_RANGE_CACHE_MAX_SIZE 6 /* log of max cached IOVA range size (in pages) */ > > Is that the same as an 'order'? i.e. IOVA_RANGE_CACHE_MAX_ORDER? Yeah, that may be better. I was just using the same name as before. > >> + >> static bool iova_rcache_insert(struct iova_domain *iovad, >> unsigned long pfn, >> unsigned long size); >> @@ -881,7 +883,14 @@ static void init_iova_rcaches(struct iova_domain *iovad) >> unsigned int cpu; >> int i; >> >> - for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) { >> + iovad->rcache_max_size = IOVA_RANGE_CACHE_MAX_SIZE; >> + >> + iovad->rcaches = kcalloc(iovad->rcache_max_size, >> + sizeof(*iovad->rcaches), GFP_KERNEL); >> + if (!iovad->rcaches) >> + return; > > Returning quietly here doesn't seem like the right thing to do. At least, I > don't think the rest of the functions here are checking rcaches against > NULL. > For sure, but that is what other code which can fail here already does, like: static void init_iova_rcaches(struct iova_domain *iovad) { ... for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) { ... rcache->cpu_rcaches = __alloc_percpu(sizeof(*cpu_rcache), cache_line_size()); if (WARN_ON(!rcache->cpu_rcaches)) continue; } and that is not safe either. This issue was raised a while ago. I don't mind trying to fix it - a slightly painful part is that it touches a few subsystems. Thanks, John _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu