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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 7DC25C43387 for ; Fri, 11 Jan 2019 03:58:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4241820870 for ; Fri, 11 Jan 2019 03:58:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730585AbfAKD6l (ORCPT ); Thu, 10 Jan 2019 22:58:41 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46208 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728472AbfAKD6l (ORCPT ); Thu, 10 Jan 2019 22:58:41 -0500 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 mx1.redhat.com (Postfix) with ESMTPS id 910E683F4C; Fri, 11 Jan 2019 03:58:40 +0000 (UTC) Received: from [10.72.12.143] (ovpn-12-143.pek2.redhat.com [10.72.12.143]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B68F81E7; Fri, 11 Jan 2019 03:58:34 +0000 (UTC) Subject: Re: [PATCH net V2] vhost: log dirty page correctly To: "Michael S. Tsirkin" Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jintack Lim References: <20190109072947.23240-1-jasowang@redhat.com> <20190109091937-mutt-send-email-mst@kernel.org> <8704a816-ec70-8e56-b141-3f17c41bb999@redhat.com> <20190110090610-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: Date: Fri, 11 Jan 2019 11:58:32 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20190110090610-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Fri, 11 Jan 2019 03:58:40 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/1/10 下午10:07, Michael S. Tsirkin wrote: > On Thu, Jan 10, 2019 at 08:37:17PM +0800, Jason Wang wrote: >> On 2019/1/9 下午10:25, Michael S. Tsirkin wrote: >>> On Wed, Jan 09, 2019 at 03:29:47PM +0800, Jason Wang wrote: >>>> Vhost dirty page logging API is designed to sync through GPA. But we >>>> try to log GIOVA when device IOTLB is enabled. This is wrong and may >>>> lead to missing data after migration. >>>> >>>> To solve this issue, when logging with device IOTLB enabled, we will: >>>> >>>> 1) reuse the device IOTLB translation result of GIOVA->HVA mapping to >>>> get HVA, for writable descriptor, get HVA through iovec. For used >>>> ring update, translate its GIOVA to HVA >>>> 2) traverse the GPA->HVA mapping to get the possible GPA and log >>>> through GPA. Pay attention this reverse mapping is not guaranteed >>>> to be unique, so we should log each possible GPA in this case. >>>> >>>> This fix the failure of scp to guest during migration. In -next, we >>>> will probably support passing GIOVA->GPA instead of GIOVA->HVA. >>>> >>>> Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API") >>>> Reported-by: Jintack Lim >>>> Cc: Jintack Lim >>>> Signed-off-by: Jason Wang >>>> --- >>>> The patch is needed for stable. >>>> Changes from V1: >>>> - return error instead of warn >>>> --- >>>> drivers/vhost/net.c | 3 +- >>>> drivers/vhost/vhost.c | 82 +++++++++++++++++++++++++++++++++++-------- >>>> drivers/vhost/vhost.h | 3 +- >>>> 3 files changed, 72 insertions(+), 16 deletions(-) >>>> >>>> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c >>>> index 36f3d0f49e60..bca86bf7189f 100644 >>>> --- a/drivers/vhost/net.c >>>> +++ b/drivers/vhost/net.c >>>> @@ -1236,7 +1236,8 @@ static void handle_rx(struct vhost_net *net) >>>> if (nvq->done_idx > VHOST_NET_BATCH) >>>> vhost_net_signal_used(nvq); >>>> if (unlikely(vq_log)) >>>> - vhost_log_write(vq, vq_log, log, vhost_len); >>>> + vhost_log_write(vq, vq_log, log, vhost_len, >>>> + vq->iov, in); >>>> total_len += vhost_len; >>>> if (unlikely(vhost_exceeds_weight(++recv_pkts, total_len))) { >>>> vhost_poll_queue(&vq->poll); >>>> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c >>>> index 9f7942cbcbb2..ee095f08ffd4 100644 >>>> --- a/drivers/vhost/vhost.c >>>> +++ b/drivers/vhost/vhost.c >>>> @@ -1733,11 +1733,70 @@ static int log_write(void __user *log_base, >>>> return r; >>>> } >>>> +static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len) >>>> +{ >>>> + struct vhost_umem *umem = vq->umem; >>>> + struct vhost_umem_node *u; >>>> + u64 gpa; >>>> + int r; >>>> + bool hit = false; >>>> + >>>> + list_for_each_entry(u, &umem->umem_list, link) { >>>> + if (u->userspace_addr < hva && >>>> + u->userspace_addr + u->size >= >>>> + hva + len) { >>> So this tries to see that the GPA range is completely within >>> the GVA region. Does this have to be the case? >> You mean e.g a buffer that crosses the boundary of two memory regions? > Yes - where hva and gva could be contigious. Ok, let me add the overlap range logging in v3. > > >>> And if yes why not return 0 below instead of hit = true? >> I think it's safe but not sure for the case like two GPAs can map to same >> HVA? > Oh I see. Yes that's possible. Document the motivation? > Ok. Thanks