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=-15.4 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 2A38FC433E6 for ; Mon, 18 Jan 2021 12:29:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E731A2231F for ; Mon, 18 Jan 2021 12:29:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391419AbhARM3C (ORCPT ); Mon, 18 Jan 2021 07:29:02 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:11554 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391480AbhARM0H (ORCPT ); Mon, 18 Jan 2021 07:26:07 -0500 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DK9v05GwMzMLhC; Mon, 18 Jan 2021 20:23:56 +0800 (CST) Received: from [10.174.184.42] (10.174.184.42) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.498.0; Mon, 18 Jan 2021 20:25:10 +0800 Subject: Re: [PATCH v2 1/2] vfio/iommu_type1: Populate full dirty when detach non-pinned group To: Alex Williamson References: <20210115092643.728-1-zhukeqian1@huawei.com> <20210115092643.728-2-zhukeqian1@huawei.com> <20210115110144.61e3c843@omen.home.shazbot.org> CC: , , , , , Kirti Wankhede , Cornelia Huck , Will Deacon , "Marc Zyngier" , Catalin Marinas , "Mark Rutland" , James Morse , "Robin Murphy" , Joerg Roedel , Daniel Lezcano , Thomas Gleixner , "Suzuki K Poulose" , Julien Thierry , Andrew Morton , Alexios Zavras , , From: Keqian Zhu Message-ID: Date: Mon, 18 Jan 2021 20:25:09 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20210115110144.61e3c843@omen.home.shazbot.org> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.184.42] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/1/16 2:01, Alex Williamson wrote: > On Fri, 15 Jan 2021 17:26:42 +0800 > Keqian Zhu wrote: > >> If a group with non-pinned-page dirty scope is detached with dirty >> logging enabled, we should fully populate the dirty bitmaps at the >> time it's removed since we don't know the extent of its previous DMA, >> nor will the group be present to trigger the full bitmap when the user >> retrieves the dirty bitmap. >> >> Fixes: d6a4c185660c ("vfio iommu: Implementation of ioctl for dirty pages tracking") >> Suggested-by: Alex Williamson >> Signed-off-by: Keqian Zhu >> --- >> drivers/vfio/vfio_iommu_type1.c | 18 +++++++++++++++++- >> 1 file changed, 17 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >> index 0b4dedaa9128..4e82b9a3440f 100644 >> --- a/drivers/vfio/vfio_iommu_type1.c >> +++ b/drivers/vfio/vfio_iommu_type1.c >> @@ -236,6 +236,19 @@ static void vfio_dma_populate_bitmap(struct vfio_dma *dma, size_t pgsize) >> } >> } >> >> +static void vfio_iommu_populate_bitmap_full(struct vfio_iommu *iommu) >> +{ >> + struct rb_node *n; >> + unsigned long pgshift = __ffs(iommu->pgsize_bitmap); >> + >> + for (n = rb_first(&iommu->dma_list); n; n = rb_next(n)) { >> + struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node); >> + >> + if (dma->iommu_mapped) >> + bitmap_set(dma->bitmap, 0, dma->size >> pgshift); >> + } >> +} >> + >> static int vfio_dma_bitmap_alloc_all(struct vfio_iommu *iommu, size_t pgsize) >> { >> struct rb_node *n; >> @@ -2415,8 +2428,11 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, >> * Removal of a group without dirty tracking may allow the iommu scope >> * to be promoted. >> */ >> - if (update_dirty_scope) >> + if (update_dirty_scope) { >> update_pinned_page_dirty_scope(iommu); >> + if (iommu->dirty_page_tracking) >> + vfio_iommu_populate_bitmap_full(iommu); >> + } >> mutex_unlock(&iommu->lock); >> } >> > > This doesn't do the right thing. This marks the bitmap dirty if: > > * The detached group dirty scope was not limited to pinned pages > > AND > > * Dirty tracking is enabled > > AND > > * The vfio_dma is *currently* (ie. after the detach) iommu_mapped > > We need to mark the bitmap dirty based on whether the vfio_dma *was* > iommu_mapped by the group that is now detached. Thanks, > > Alex > Hi Alex, Yes, I missed this point again :-(. The update_dirty_scope means we detached an iommu backed group, and that means the vfio_dma *was* iommu_mapped by this group, so we can populate full bitmap unconditionally, right? Thanks, Keqian > . >