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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 725EAC06513 for ; Thu, 4 Jul 2019 04:32:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 50E37218A4 for ; Thu, 4 Jul 2019 04:32:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726016AbfGDEcG (ORCPT ); Thu, 4 Jul 2019 00:32:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49668 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725795AbfGDEcG (ORCPT ); Thu, 4 Jul 2019 00:32:06 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id EE19F3082132; Thu, 4 Jul 2019 04:32:00 +0000 (UTC) Received: from [10.72.12.202] (ovpn-12-202.pek2.redhat.com [10.72.12.202]) by smtp.corp.redhat.com (Postfix) with ESMTP id B705F968C7; Thu, 4 Jul 2019 04:31:50 +0000 (UTC) Subject: Re: [RFC v2] vhost: introduce mdev based hardware vhost backend To: Tiwei Bie Cc: mst@redhat.com, alex.williamson@redhat.com, maxime.coquelin@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, dan.daly@intel.com, cunming.liang@intel.com, zhihong.wang@intel.com References: <20190703091339.1847-1-tiwei.bie@intel.com> <7b8279b2-aa7e-7adc-eeff-20dfaf4400d0@redhat.com> <20190703115245.GA22374@___> <64833f91-02cd-7143-f12e-56ab93b2418d@redhat.com> <20190703130817.GA1978@___> From: Jason Wang Message-ID: Date: Thu, 4 Jul 2019 12:31:48 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190703130817.GA1978@___> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Thu, 04 Jul 2019 04:32:06 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2019/7/3 下午9:08, Tiwei Bie wrote: > On Wed, Jul 03, 2019 at 08:16:23PM +0800, Jason Wang wrote: >> On 2019/7/3 下午7:52, Tiwei Bie wrote: >>> On Wed, Jul 03, 2019 at 06:09:51PM +0800, Jason Wang wrote: >>>> On 2019/7/3 下午5:13, Tiwei Bie wrote: >>>>> Details about this can be found here: >>>>> >>>>> https://lwn.net/Articles/750770/ >>>>> >>>>> What's new in this version >>>>> ========================== >>>>> >>>>> A new VFIO device type is introduced - vfio-vhost. This addressed >>>>> some comments from here:https://patchwork.ozlabs.org/cover/984763/ >>>>> >>>>> Below is the updated device interface: >>>>> >>>>> Currently, there are two regions of this device: 1) CONFIG_REGION >>>>> (VFIO_VHOST_CONFIG_REGION_INDEX), which can be used to setup the >>>>> device; 2) NOTIFY_REGION (VFIO_VHOST_NOTIFY_REGION_INDEX), which >>>>> can be used to notify the device. >>>>> >>>>> 1. CONFIG_REGION >>>>> >>>>> The region described by CONFIG_REGION is the main control interface. >>>>> Messages will be written to or read from this region. >>>>> >>>>> The message type is determined by the `request` field in message >>>>> header. The message size is encoded in the message header too. >>>>> The message format looks like this: >>>>> >>>>> struct vhost_vfio_op { >>>>> __u64 request; >>>>> __u32 flags; >>>>> /* Flag values: */ >>>>> #define VHOST_VFIO_NEED_REPLY 0x1 /* Whether need reply */ >>>>> __u32 size; >>>>> union { >>>>> __u64 u64; >>>>> struct vhost_vring_state state; >>>>> struct vhost_vring_addr addr; >>>>> } payload; >>>>> }; >>>>> >>>>> The existing vhost-kernel ioctl cmds are reused as the message >>>>> requests in above structure. >>>> Still a comments like V1. What's the advantage of inventing a new protocol? >>> I'm trying to make it work in VFIO's way.. >>> >>>> I believe either of the following should be better: >>>> >>>> - using vhost ioctl,  we can start from SET_VRING_KICK/SET_VRING_CALL and >>>> extend it with e.g notify region. The advantages is that all exist userspace >>>> program could be reused without modification (or minimal modification). And >>>> vhost API hides lots of details that is not necessary to be understood by >>>> application (e.g in the case of container). >>> Do you mean reusing vhost's ioctl on VFIO device fd directly, >>> or introducing another mdev driver (i.e. vhost_mdev instead of >>> using the existing vfio_mdev) for mdev device? >> Can we simply add them into ioctl of mdev_parent_ops? > Right, either way, these ioctls have to be and just need to be > added in the ioctl of the mdev_parent_ops. But another thing we > also need to consider is that which file descriptor the userspace > will do the ioctl() on. So I'm wondering do you mean let the > userspace do the ioctl() on the VFIO device fd of the mdev > device? > Yes. Is there any other way btw? Thanks