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=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT 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 231FAC433E9 for ; Thu, 28 Jan 2021 15:18:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E945B64DEF for ; Thu, 28 Jan 2021 15:18:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231244AbhA1PSv (ORCPT ); Thu, 28 Jan 2021 10:18:51 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:11213 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229504AbhA1PSs (ORCPT ); Thu, 28 Jan 2021 10:18:48 -0500 Received: from DGGEMS413-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4DRPFQ4vV3zlC5j; Thu, 28 Jan 2021 23:16:26 +0800 (CST) Received: from DESKTOP-5IS4806.china.huawei.com (10.174.184.42) by DGGEMS413-HUB.china.huawei.com (10.3.19.213) with Microsoft SMTP Server id 14.3.498.0; Thu, 28 Jan 2021 23:17:53 +0800 From: Keqian Zhu To: , , , , , Will Deacon , "Alex Williamson" , Marc Zyngier , Catalin Marinas CC: Kirti Wankhede , Cornelia Huck , Mark Rutland , James Morse , "Robin Murphy" , Suzuki K Poulose , , , , Subject: [RFC PATCH 00/11] vfio/iommu_type1: Implement dirty log tracking based on smmuv3 HTTU Date: Thu, 28 Jan 2021 23:17:31 +0800 Message-ID: <20210128151742.18840-1-zhukeqian1@huawei.com> X-Mailer: git-send-email 2.8.4.windows.1 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.184.42] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi all, This patch series implement a new dirty log tracking method for vfio dma. Intention： As we know, vfio live migration is an important and valuable feature, but there are still many hurdles to solve, including migration of interrupt, device state, DMA dirty log tracking, and etc. For now, the only dirty log tracking interface is pinning. It has some drawbacks: 1. Only smart vendor drivers are aware of this. 2. It's coarse-grained, the pinned-scope is generally bigger than what the device actually access. 3. It can't track dirty continuously and precisely, vfio populates all pinned-scope as dirty. So it doesn't work well with iteratively dirty log handling. About SMMU HTTU: HTTU (Hardware Translation Table Update) is a feature of ARM SMMUv3, it can update access flag or/and dirty state of the TTD (Translation Table Descriptor) by hardware. With HTTU, stage1 TTD is classified into 3 types: DBM bit AP[2](readonly bit) 1. writable_clean 1 1 2. writable_dirty 1 0 3. readonly 0 1 If HTTU_HD (manage dirty state) is enabled, smmu can change TTD from writable_clean to writable_dirty. Then software can scan TTD to sync dirty state into dirty bitmap. With this feature, we can track the dirty log of DMA continuously and precisely. About this series: Patch 1-3: Add feature detection for smmu HTTU and enable HTTU for smmu stage1 mapping. And add feature detection for smmu BBML. We need to split block mapping when start dirty log tracking and merge page mapping when stop dirty log tracking, which requires break-before-make procedure. But it might cause problems when the TTD is alive. The I/O streams might not tolerate translation faults. So BBML should be used. Patch 4-7: Add four interfaces (split_block, merge_page, sync_dirty_log and clear_dirty_log) in IOMMU layer, they are essential to implement dma dirty log tracking for vfio. We implement these interfaces for arm smmuv3. Patch 8: Add HWDBM (Hardware Dirty Bit Management) device feature reporting in IOMMU layer. Patch9-11: Implement a new dirty log tracking method for vfio based on iommu hwdbm. A new ioctl operation named VFIO_DIRTY_LOG_MANUAL_CLEAR is added, which can eliminate some redundant dirty handling of userspace. Optimizations TO Do: 1. We recognized that each smmu_domain (a vfio_container may has several smmu_domain) has its own stage1 mapping, and we must scan all these mapping to sync dirty state. We plan to refactor smmu_domain to support more than one smmu in one smmu_domain, then these smmus can share a same stage1 mapping. 2. We also recognized that scan TTD is a hotspot of performance. Recently, I have implement a SW/HW conbined dirty log tracking at MMU side [1], which can effectively solve this problem. This idea can be applied to smmu side too. Thanks, Keqian [1] https://lore.kernel.org/linux-arm-kernel/20210126124444.27136-1-zhukeqian1@huawei.com/ jiangkunkun (11): iommu/arm-smmu-v3: Add feature detection for HTTU iommu/arm-smmu-v3: Enable HTTU for SMMU stage1 mapping iommu/arm-smmu-v3: Add feature detection for BBML iommu/arm-smmu-v3: Split block descriptor to a span of page iommu/arm-smmu-v3: Merge a span of page to block descriptor iommu/arm-smmu-v3: Scan leaf TTD to sync hardware dirty log iommu/arm-smmu-v3: Clear dirty log according to bitmap iommu/arm-smmu-v3: Add HWDBM device feature reporting vfio/iommu_type1: Add HWDBM status maintanance vfio/iommu_type1: Optimize dirty bitmap population based on iommu HWDBM vfio/iommu_type1: Add support for manual dirty log clear drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 138 ++++++- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 14 + drivers/iommu/io-pgtable-arm.c | 392 +++++++++++++++++++- drivers/iommu/iommu.c | 227 ++++++++++++ drivers/vfio/vfio_iommu_type1.c | 235 +++++++++++- include/linux/io-pgtable.h | 14 + include/linux/iommu.h | 55 +++ include/uapi/linux/vfio.h | 28 +- 8 files changed, 1093 insertions(+), 10 deletions(-) -- 2.19.1