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=-5.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 2BF37C433E7 for ; Mon, 12 Oct 2020 02:57:45 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9129B20757 for ; Mon, 12 Oct 2020 02:57:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iwrs/jPu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9129B20757 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:53024 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kRo1v-0002QK-90 for qemu-devel@archiver.kernel.org; Sun, 11 Oct 2020 22:57:43 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51458) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kRo11-0001zY-Q7 for qemu-devel@nongnu.org; Sun, 11 Oct 2020 22:56:47 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:23112) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kRo0y-0005S1-4I for qemu-devel@nongnu.org; Sun, 11 Oct 2020 22:56:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602471401; 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=OoJmvJjEIQ9uKE2EVMnMh55DvhuNBQBgDD00b/OzaYM=; b=iwrs/jPudOAwQxBJaa93BeGXtTKi90AmztQtdOg2DstXsWdjX3T704DDUn9IZh6Is4J3kZ ygQvk2kXJ7CwgYK9yKdJjnZYDoiMJXYcjAPq/cP5ipzQjgzsRMeCrVfztZguckYsCeEl8X lS+LwONJFGcqP6DY98tsNITfo+VaPPg= 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-140-ACi833VvOwmZPd8SWFXLeA-1; Sun, 11 Oct 2020 22:56:39 -0400 X-MC-Unique: ACi833VvOwmZPd8SWFXLeA-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 424121868400; Mon, 12 Oct 2020 02:56:38 +0000 (UTC) Received: from [10.72.13.74] (ovpn-13-74.pek2.redhat.com [10.72.13.74]) by smtp.corp.redhat.com (Postfix) with ESMTP id D79CB27CC5; Mon, 12 Oct 2020 02:56:15 +0000 (UTC) Subject: Re: Outline for VHOST_USER_PROTOCOL_F_VDPA To: Stefan Hajnoczi , =?UTF-8?Q?Marc-Andr=c3=a9_Lureau?= References: <20200928092537.GA44353@stefanha-x1.localdomain> <20200928153257.GA173977@stefanha-x1.localdomain> From: Jason Wang Message-ID: Date: Mon, 12 Oct 2020 10:56:14 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200928153257.GA173977@stefanha-x1.localdomain> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jasowang@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Received-SPF: pass client-ip=63.128.21.124; envelope-from=jasowang@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/11 21:16:19 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=-1, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: lulu@redhat.com, tiwei.bie@intel.com, "Michael S. Tsirkin" , qemu-devel , Raphael Norwitz , "Coquelin, Maxime" , "Hoffmann, Gerd" , Felipe Franciosi , Nikos Dragazis , "Liu, Changpeng" , Daniele Buono Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2020/9/28 下午11:32, Stefan Hajnoczi wrote: > On Mon, Sep 28, 2020 at 03:21:56PM +0400, Marc-André Lureau wrote: >> On Mon, Sep 28, 2020 at 1:25 PM Stefan Hajnoczi >> Where this converges with multi-process QEMU >>> -------------------------------------------- >>> At this point QEMU can run ad-hoc vhost-user backends using existing >>> VIRTIO device models. It is possible to go further by creating a >>> qemu-dev launcher executable that implements the vhost-user spec's >>> "Backend program conventions". This way a minimal device emulator >>> executable hosts the device instead of a full system emulator. >>> >>> The requirements for this are similar to the multi-process QEMU effort, >>> which aims to run QEMU devices as separate processes. One of the main >>> open questions is how to design build system and Kconfig support for >>> building minimal device emulator executables. >>> >>> In the case of vhost-user-net the qemu-dev-vhost-user-net executable >>> would contain virtio-net-device, vhost-user-backend, any netdevs the >>> user wishes to include, a QMP monitor, and a vhost-user backend >>> command-line interface. >>> >>> Where does this leave us? QEMU's existing VIRTIO device models can be >>> used as vhost-user devices and run in a separate processes from the VMM. >>> It's a great way of reusing code and having the flexibility to deploy it >>> in the way that makes most sense for the intended use case. >>> >> My understanding is that this would only be able to expose virtio >> devices from external processes. But vfio-user could expose more kinds >> of devices, including the virtio devices. >> >> Shouldn't we focus on vfio-user now, as the general out-of-process >> device solution? Similar question could be asked for vDPA(kernel) vs VFIO(kernel). > Eventually vfio-user can replace vhost-user. However, vfio-user > development will take longer so for anyone already comfortable with > vhost-user I think extending the protocol with vDPA ioctls is > attractive. My understanding is for vhost-user may advantages: - well defined interface, this helps a lot for e.g live migration (cross migration among different vendors), backend disconnection, device failover and there will be no vendor lock - high level abstraction, not tie to a specific bus implementation, micro VM that want to get rid of PCI can use MMIO transport So it doesn't conflict with vfio(-user) which is more suitable for any vendor specific device (API)s. Thanks > > Maybe we can get more organized around vfio-user and make progress > quicker? > > Stefan