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,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 DEC47C433B4 for ; Wed, 14 Apr 2021 07:24:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3CB4613B1 for ; Wed, 14 Apr 2021 07:24:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349736AbhDNHZF (ORCPT ); Wed, 14 Apr 2021 03:25:05 -0400 Received: from mga07.intel.com ([134.134.136.100]:38252 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349710AbhDNHYg (ORCPT ); Wed, 14 Apr 2021 03:24:36 -0400 IronPort-SDR: zYFUc1Z3Bhf+6/AqwZTL1v89T6AkF1AuPrynnURcFUyybNuDY9vOV34m6X2G4DTeOAhknHKBFA xfDXn1KbSLfg== X-IronPort-AV: E=McAfee;i="6200,9189,9953"; a="258552405" X-IronPort-AV: E=Sophos;i="5.82,221,1613462400"; d="scan'208";a="258552405" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Apr 2021 00:24:13 -0700 IronPort-SDR: 35lROPy9KaI3sWZf4uqKtjH/Qunpt9OTUZ5AFPasffdrQiGF7IKnLpGAMJwBXoXQVlETsZ32D6 mVt3msA3+Tgw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.82,221,1613462400"; d="scan'208";a="443720741" Received: from allen-box.sh.intel.com (HELO [10.239.159.128]) ([10.239.159.128]) by fmsmga004.fm.intel.com with ESMTP; 14 Apr 2021 00:24:09 -0700 Cc: baolu.lu@linux.intel.com, Alex Williamson , Cornelia Huck , Kirti Wankhede , wanghaibin.wang@huawei.com, jiangkunkun@huawei.com, yuzenghui@huawei.com, lushenming@huawei.com Subject: Re: [PATCH v3 02/12] iommu: Add iommu_split_block interface To: Keqian Zhu , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, Robin Murphy , Will Deacon , Joerg Roedel , Yi Sun , Jean-Philippe Brucker , Jonathan Cameron , Tian Kevin References: <20210413085457.25400-1-zhukeqian1@huawei.com> <20210413085457.25400-3-zhukeqian1@huawei.com> From: Lu Baolu Message-ID: Date: Wed, 14 Apr 2021 15:14:32 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210413085457.25400-3-zhukeqian1@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/13/21 4:54 PM, Keqian Zhu wrote: > Block(largepage) mapping is not a proper granule for dirty log tracking. > Take an extreme example, if DMA writes one byte, under 1G mapping, the > dirty amount reported is 1G, but under 4K mapping, the dirty amount is > just 4K. > > This adds a new interface named iommu_split_block in IOMMU base layer. > A specific IOMMU driver can invoke it during start dirty log. If so, the > driver also need to realize the split_block iommu ops. > > We flush all iotlbs after the whole procedure is completed to ease the > pressure of IOMMU, as we will hanle a huge range of mapping in general. > > Signed-off-by: Keqian Zhu > Signed-off-by: Kunkun Jiang > --- > drivers/iommu/iommu.c | 41 +++++++++++++++++++++++++++++++++++++++++ > include/linux/iommu.h | 11 +++++++++++ > 2 files changed, 52 insertions(+) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 667b2d6d2fc0..bb413a927870 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -2721,6 +2721,47 @@ int iommu_domain_set_attr(struct iommu_domain *domain, > } > EXPORT_SYMBOL_GPL(iommu_domain_set_attr); > > +int iommu_split_block(struct iommu_domain *domain, unsigned long iova, > + size_t size) > +{ > + const struct iommu_ops *ops = domain->ops; > + unsigned int min_pagesz; > + size_t pgsize; > + bool flush = false; > + int ret = 0; > + > + if (unlikely(!ops || !ops->split_block)) > + return -ENODEV; > + > + min_pagesz = 1 << __ffs(domain->pgsize_bitmap); > + if (!IS_ALIGNED(iova | size, min_pagesz)) { > + pr_err("unaligned: iova 0x%lx size 0x%zx min_pagesz 0x%x\n", > + iova, size, min_pagesz); > + return -EINVAL; > + } > + > + while (size) { > + flush = true; > + > + pgsize = iommu_pgsize(domain, iova, size); > + > + ret = ops->split_block(domain, iova, pgsize); > + if (ret) > + break; > + > + pr_debug("split handled: iova 0x%lx size 0x%zx\n", iova, pgsize); > + > + iova += pgsize; > + size -= pgsize; > + } > + > + if (flush) > + iommu_flush_iotlb_all(domain); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(iommu_split_block); Do you really have any consumers of this interface other than the dirty bit tracking? If not, I don't suggest to make this as a generic IOMMU interface. There is an implicit requirement for such interfaces. The iommu_map/unmap(iova, size) shouldn't be called at the same time. Currently there's no such sanity check in the iommu core. A poorly written driver could mess up the kernel by misusing this interface. This also applies to iommu_merge_page(). Best regards, baolu