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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 2C512C43387 for ; Tue, 8 Jan 2019 10:12:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EBD14206B7 for ; Tue, 8 Jan 2019 10:12:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728614AbfAHKMq (ORCPT ); Tue, 8 Jan 2019 05:12:46 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34662 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727001AbfAHKMp (ORCPT ); Tue, 8 Jan 2019 05:12:45 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A87EA637FF; Tue, 8 Jan 2019 10:12:45 +0000 (UTC) Received: from [10.72.12.122] (ovpn-12-122.pek2.redhat.com [10.72.12.122]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6B3D52270A; Tue, 8 Jan 2019 10:12:41 +0000 (UTC) Subject: Re: [RFC PATCH V3 0/5] Hi: To: "Michael S. Tsirkin" Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, davem@davemloft.net References: <20181229124656.3900-1-jasowang@redhat.com> <20190104163516-mutt-send-email-mst@kernel.org> <68727e1b-1d51-0596-29c3-931475dd5dab@redhat.com> <20190107094516-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: <682d520e-00e3-cdaa-d51e-23524ae48854@redhat.com> Date: Tue, 8 Jan 2019 18:12:38 +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: <20190107094516-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 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Tue, 08 Jan 2019 10:12:45 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/1/7 下午10:47, Michael S. Tsirkin wrote: > On Mon, Jan 07, 2019 at 02:58:08PM +0800, Jason Wang wrote: >> On 2019/1/5 上午5:41, Michael S. Tsirkin wrote: >>> On Sat, Dec 29, 2018 at 08:46:51PM +0800, Jason Wang wrote: >>>> This series tries to access virtqueue metadata through kernel virtual >>>> address instead of copy_user() friends since they had too much >>>> overheads like checks, spec barriers or even hardware feature >>>> toggling. >>> I think it's a reasonable approach. >>> However I need to look at whether and which mmu notifiers are invoked before >>> writeback. Do you know? >> >> I don't know but just looking at the MMU notifier ops definition, there's no >> such callback if my understanding is correct. >> >> Thanks > In that case how are you making sure used ring updates are written back? > If they aren't guest will crash ... I think this is the writeback issue you mentioned early. I don't do a followup on the pointer but it looks to me some work is ongoing to fix the issue. I can investigate it more, but it's not something new, consider the case of VFIO. Thanks