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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 B6FCEC43603 for ; Wed, 18 Dec 2019 21:39:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CB4A21582 for ; Wed, 18 Dec 2019 21:39:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="e/PHyS+W" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726539AbfLRVjM (ORCPT ); Wed, 18 Dec 2019 16:39:12 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:25394 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726387AbfLRVjM (ORCPT ); Wed, 18 Dec 2019 16:39:12 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1576705150; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=u9TtCci2FuLajUtFOw5B/HodtCZRSzWxgnpe0HYK4bg=; b=e/PHyS+WzhcioDHG9fRTHI83wk3APbJCx+9CCS8qu8du02DJwvLP3D9rCEsvsBFrmXZ3ie 5FQ0lMlfvJiayczd6EVY1XceHcKAxru0qqGHeeS4HxDiZaFdRshbIobdZ1G91NThJKBjJz 9g616ZkG29WSP1yAiZZ40+Ze2nJnNoA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-326-TtPgruxiOy2jW2yv518w1w-1; Wed, 18 Dec 2019 16:39:07 -0500 X-MC-Unique: TtPgruxiOy2jW2yv518w1w-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 08FF7801E6D; Wed, 18 Dec 2019 21:39:05 +0000 (UTC) Received: from x1.home (ovpn-116-26.phx2.redhat.com [10.3.116.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id 36C0426DEC; Wed, 18 Dec 2019 21:39:03 +0000 (UTC) Date: Wed, 18 Dec 2019 14:39:02 -0700 From: Alex Williamson To: Kirti Wankhede Cc: Yan Zhao , "cjia@nvidia.com" , "Tian, Kevin" , "Yang, Ziye" , "Liu, Changpeng" , "Liu, Yi L" , "mlevitsk@redhat.com" , "eskultet@redhat.com" , "cohuck@redhat.com" , "dgilbert@redhat.com" , "jonathan.davies@nutanix.com" , "eauger@redhat.com" , "aik@ozlabs.ru" , "pasic@linux.ibm.com" , "felipe@nutanix.com" , "Zhengxiao.zx@Alibaba-inc.com" , "shuangtai.tst@alibaba-inc.com" , "Ken.Xue@amd.com" , "Wang, Zhi A" , "qemu-devel@nongnu.org" , "kvm@vger.kernel.org" Subject: Re: [PATCH v10 Kernel 4/5] vfio iommu: Implementation of ioctl to for dirty pages tracking. Message-ID: <20191218143902.3c9b06df@x1.home> In-Reply-To: <17ac4c3b-5f7c-0e52-2c2b-d847d4d4e3b1@nvidia.com> References: <1576527700-21805-1-git-send-email-kwankhede@nvidia.com> <1576527700-21805-5-git-send-email-kwankhede@nvidia.com> <20191217051513.GE21868@joy-OptiPlex-7040> <17ac4c3b-5f7c-0e52-2c2b-d847d4d4e3b1@nvidia.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 17 Dec 2019 14:54:14 +0530 Kirti Wankhede wrote: > On 12/17/2019 10:45 AM, Yan Zhao wrote: > > On Tue, Dec 17, 2019 at 04:21:39AM +0800, Kirti Wankhede wrote: > >> + } else if (range.flags & > >> + VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP) { > >> + uint64_t iommu_pgmask; > >> + unsigned long pgshift = __ffs(range.pgsize); > >> + unsigned long *bitmap; > >> + long bsize; > >> + > >> + iommu_pgmask = > >> + ((uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu))) - 1; > >> + > >> + if (((range.pgsize - 1) & iommu_pgmask) != > >> + (range.pgsize - 1)) > >> + return -EINVAL; > >> + > >> + if (range.iova & iommu_pgmask) > >> + return -EINVAL; > >> + if (!range.size || range.size > SIZE_MAX) > >> + return -EINVAL; > >> + if (range.iova + range.size < range.iova) > >> + return -EINVAL; > >> + > >> + bsize = verify_bitmap_size(range.size >> pgshift, > >> + range.bitmap_size); > >> + if (bsize) > >> + return ret; > >> + > >> + bitmap = kmalloc(bsize, GFP_KERNEL); > >> + if (!bitmap) > >> + return -ENOMEM; > >> + > >> + ret = copy_from_user(bitmap, > >> + (void __user *)range.bitmap, bsize) ? -EFAULT : 0; > >> + if (ret) > >> + goto bitmap_exit; > >> + > >> + iommu->dirty_page_tracking = false; > > why iommu->dirty_page_tracking is false here? > > suppose this ioctl can be called several times. > > > > This ioctl can be called several times, but once this ioctl is called > that means vCPUs are stopped and VFIO devices are stopped (i.e. in > stop-and-copy phase) and dirty pages bitmap are being queried by user. Do not assume how userspace works or its intent. If dirty tracking is on, it should remain on until the user turns it off. We cannot assume userspace uses a one-shot approach. Thanks, Alex