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=-3.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 2EA03C64E7A for ; Tue, 1 Dec 2020 14:19:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A7F0A20758 for ; Tue, 1 Dec 2020 14:19:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bytedance-com.20150623.gappssmtp.com header.i=@bytedance-com.20150623.gappssmtp.com header.b="W+Z72+nC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730494AbgLAOTe (ORCPT ); Tue, 1 Dec 2020 09:19:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44436 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726402AbgLAOTe (ORCPT ); Tue, 1 Dec 2020 09:19:34 -0500 Received: from mail-ed1-x542.google.com (mail-ed1-x542.google.com [IPv6:2a00:1450:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0B57BC0613CF for ; Tue, 1 Dec 2020 06:18:48 -0800 (PST) Received: by mail-ed1-x542.google.com with SMTP id d18so3461705edt.7 for ; Tue, 01 Dec 2020 06:18:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=fCXvBEwcMVtc8hy65Pn2ZYYH6fAo0MB7m9fPCxDsyC4=; b=W+Z72+nCeKjIgW8wSuAhRLQinqBk1lvJSqsTz/cAHZFK5n1PzHcckZ34DDaQf+Q1lA U+yEJ8fY/gfdeCYsWN+BZmMaaE/eiAK2mAPQcD82PKTch39mssy9vG7jfrQVmJo0FssH H+1HfQQdRaOCrqrCExS3usLPplj2SR58F0ftmPcA5pTw1MTDOZ/e0Lui88G/ynO3A24e rXy+vf25mZH+GKs04wXrgBQUi2MOj8Fl4/ZBbJhK8YVQ/+QJEAOrCfwSWPcC+igYu7h9 Sy5vLuihM6M5PotiXao7nNYsrfp9rJcn6ME+EqZTtqL+ye1mR33vvbUkAYJMF612bssM Gucg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=fCXvBEwcMVtc8hy65Pn2ZYYH6fAo0MB7m9fPCxDsyC4=; b=oamQbSd9uu7ySBeoPwI0qTJFRuDBZeSjYwA1BMEIOdv+/eo/HjbCDH52wqGxYiVNLN guQlBBF7GoPxbD8I2gXO6NS+e5rt/6gRpEe0skgW2I7k4J16YRhWKh5ZJXibVH2QmPqe t0j7rPy/EMO/DR4eb9egAaKyIUKsphmbhx6MZvcP3jThPXxsxNSfh8OBuRSqrHgKGhNL oG8aRSJ4fEHKjglXxDxd7Eq0QoBTRxSdlIvhAAvPtZEM7q5o0RoOH2pFQBraJTUwRohf h+gIuMnHtqOtrSfc65vtKXYIBBGJHYbpn1UC88cAgzBHvXAWO8MKGVDzods/WTtAWDTv nTmA== X-Gm-Message-State: AOAM532rTJ12GGJ08kRe1bSAd6BIQcxXhmraw29V/1kES9bfQw5RPMvW /LKRX0dKTYczCkFyKe3jpmCbod8eEHwsn5ZJXccr X-Google-Smtp-Source: ABdhPJzDLWpx2EyYcsmsQ4VKUvuCZD9ajLFsXWAq668o10RFtGhFqVtSkcD/viTejS+wR52Kc/9moegK4zoPcdh+mCc= X-Received: by 2002:aa7:c60c:: with SMTP id h12mr3253691edq.145.1606832326725; Tue, 01 Dec 2020 06:18:46 -0800 (PST) MIME-Version: 1.0 References: <20201112064005.349268-1-parav@nvidia.com> <5b2235f6-513b-dbc9-3670-e4c9589b4d1f@redhat.com> <182708df-1082-0678-49b2-15d0199f20df@redhat.com> <7f80eeed-f5d3-8c6f-1b8c-87b7a449975c@redhat.com> In-Reply-To: From: Yongji Xie Date: Tue, 1 Dec 2020 22:18:35 +0800 Message-ID: Subject: Re: [External] Re: [PATCH 0/7] Introduce vdpa management tool To: Parav Pandit Cc: Jason Wang , "virtualization@lists.linux-foundation.org" , "Michael S. Tsirkin" , Eli Cohen , "netdev@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Archived-At: List-Archive: List-Post: On Tue, Dec 1, 2020 at 7:32 PM Parav Pandit wrote: > > > > > From: Yongji Xie > > Sent: Tuesday, December 1, 2020 3:26 PM > > > > On Tue, Dec 1, 2020 at 2:25 PM Jason Wang wrote: > > > > > > > > > On 2020/11/30 =E4=B8=8B=E5=8D=883:07, Yongji Xie wrote: > > > >>> Thanks for adding me, Jason! > > > >>> > > > >>> Now I'm working on a v2 patchset for VDUSE (vDPA Device in > > > >>> Userspace) [1]. This tool is very useful for the vduse device. So > > > >>> I'm considering integrating this into my v2 patchset. But there i= s > > > >>> one problem=EF=BC=9A > > > >>> > > > >>> In this tool, vdpa device config action and enable action are > > > >>> combined into one netlink msg: VDPA_CMD_DEV_NEW. But in vduse > > > >>> case, it needs to be splitted because a chardev should be created > > > >>> and opened by a userspace process before we enable the vdpa devic= e > > > >>> (call vdpa_register_device()). > > > >>> > > > >>> So I'd like to know whether it's possible (or have some plans) to > > > >>> add two new netlink msgs something like: VDPA_CMD_DEV_ENABLE > > and > > > >>> VDPA_CMD_DEV_DISABLE to make the config path more flexible. > > > >>> > > > >> Actually, we've discussed such intermediate step in some early > > > >> discussion. It looks to me VDUSE could be one of the users of this= . > > > >> > > > >> Or I wonder whether we can switch to use anonymous inode(fd) for > > > >> VDUSE then fetching it via an VDUSE_GET_DEVICE_FD ioctl? > > > >> > > > > Yes, we can. Actually the current implementation in VDUSE is like > > > > this. But seems like this is still a intermediate step. The fd > > > > should be binded to a name or something else which need to be > > > > configured before. > > > > > > > > > The name could be specified via the netlink. It looks to me the real > > > issue is that until the device is connected with a userspace, it can'= t > > > be used. So we also need to fail the enabling if it doesn't opened. > > > > > > > Yes, that's true. So you mean we can firstly try to fetch the fd binded= to a > > name/vduse_id via an VDUSE_GET_DEVICE_FD, then use the > > name/vduse_id as a attribute to create vdpa device? It looks fine to me= . > > I probably do not well understand. I tried reading patch [1] and few thin= gs do not look correct as below. > Creating the vdpa device on the bus device and destroying the device from= the workqueue seems unnecessary and racy. > > It seems vduse driver needs > This is something should be done as part of the vdpa dev add command, ins= tead of connecting two sides separately and ensuring race free access to it= . > > So VDUSE_DEV_START and VDUSE_DEV_STOP should possibly be avoided. > Yes, we can avoid these two ioctls with the help of the management tool. > $ vdpa dev add parentdev vduse_mgmtdev type net name foo2 > > When above command is executed it creates necessary vdpa device foo2 on t= he bus. > When user binds foo2 device with the vduse driver, in the probe(), it cre= ates respective char device to access it from user space. But vduse driver is not a vdpa bus driver. It works like vdpasim driver, but offloads the data plane and control plane to a user space process. Thanks, Yongji