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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 28F8AC433F5 for ; Mon, 13 Dec 2021 02:48:37 +0000 (UTC) Received: from localhost ([::1]:59930 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mwbOG-0005ca-GH for qemu-devel@archiver.kernel.org; Sun, 12 Dec 2021 21:48:36 -0500 Received: from eggs.gnu.org ([209.51.188.92]:58732) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mwbN2-0004v4-DS for qemu-devel@nongnu.org; Sun, 12 Dec 2021 21:47:20 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:28190) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mwbMz-0003MX-80 for qemu-devel@nongnu.org; Sun, 12 Dec 2021 21:47:19 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639363636; 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: in-reply-to:in-reply-to:references:references; bh=DyM28bBfqojqBGUxvZvWOTMo/BK3yU+vxSCnNOI3D4c=; b=GOH8XdMOP4l0zXvt5xEcpXtOE124nW5tf11KM3o55W4W+1x9XFEfA/S/ixoh3P+ty9M1gS PUQsP551TsEaivPj4WQsaL28gX4ptss04UC06LbOWq2IvXL7BmJjUysYjb4d1AwfFRP8vq M6OS5gVY8+6z5V/v7qVvRv3OarTXVrg= Received: from mail-lf1-f71.google.com (mail-lf1-f71.google.com [209.85.167.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-569-Wevtt4wLN-m_y1KWg6tMMw-1; Sun, 12 Dec 2021 21:47:13 -0500 X-MC-Unique: Wevtt4wLN-m_y1KWg6tMMw-1 Received: by mail-lf1-f71.google.com with SMTP id s11-20020a195e0b000000b0041c0a47fb77so6819324lfb.20 for ; Sun, 12 Dec 2021 18:47:13 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=DyM28bBfqojqBGUxvZvWOTMo/BK3yU+vxSCnNOI3D4c=; b=RPu/zLNYah2jHDeqJlbASmIxRiuLox2yLEPi7ykSDBbjV93N22VcHokgacgHKFUbyS M9/3P/+xX4ygxliTwao0861d4Zl0w+ZwiwEyzypnERtBc7X3mGT9cTUFB0yg2fJmj5lO 3s7Spv9LEZiMGKbKR96y0lV5VcJL0U6p0Y8m7BkG/R3AHwRcGi4mh61/SEpEJKXXP+Zk R+T2phleeNquW7xXTLk7lP/f0/9JImrd0+WngFMoQLmk7BYOcG+xmnBHl9qLy4BHDw0g VD+k7YgREU552+WnsAah/MEZ+xcMf+uxQmw0A1jjaEiPKFmkOux5UJ/SLzmKfkAzaKPh SUpA== X-Gm-Message-State: AOAM532AqgRpYYyHxf36ZfBN0rD2KOufxxhBvMtZTk9BdQCjqqcfbTej /Hs8tmZrZjyFacSimElqOslLcS4qMua82BkB+QIiXXrmMRT4vLixXZaF1FRsZa8jxLWjsclb9Cf 8ZP7LiOkAuPVVSrzxGT6bZIuonLgLN44= X-Received: by 2002:ac2:518b:: with SMTP id u11mr26567690lfi.498.1639363631446; Sun, 12 Dec 2021 18:47:11 -0800 (PST) X-Google-Smtp-Source: ABdhPJxHyIWGgcreoAd/B+ZTkuCLysU6oX0NI15bIeBcLWlwqPIAvArigPSdS7BGt9TE8vgCdW0E3ewlI9bYa4OUW3U= X-Received: by 2002:ac2:518b:: with SMTP id u11mr26567667lfi.498.1639363631203; Sun, 12 Dec 2021 18:47:11 -0800 (PST) MIME-Version: 1.0 References: <20211208052010.1719-1-longpeng2@huawei.com> <721bbc1c27f545babdfbd17e1461e9f2@huawei.com> <20211212042818-mutt-send-email-mst@kernel.org> In-Reply-To: <20211212042818-mutt-send-email-mst@kernel.org> From: Jason Wang Date: Mon, 13 Dec 2021 10:47:00 +0800 Message-ID: Subject: Re: [RFC] vhost-vdpa-net: add vhost-vdpa-net host device support To: "Michael S. Tsirkin" 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" Received-SPF: pass client-ip=170.10.129.124; envelope-from=jasowang@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.713, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=-0.01, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "qemu-devel@nongnu.org" , Yechuan , "xieyongji@bytedance.com" , "Gonglei \(Arei\)" , "parav@nvidia.com" , Stefan Hajnoczi , "Longpeng \(Mike, Cloud Infrastructure Service Product Dept.\)" , "sgarzare@redhat.com" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Sun, Dec 12, 2021 at 5:30 PM Michael S. Tsirkin wrote: > > On Sat, Dec 11, 2021 at 03:00:27AM +0000, Longpeng (Mike, Cloud Infrastructure Service Product Dept.) wrote: > > > > > > > -----Original Message----- > > > From: Stefan Hajnoczi [mailto:stefanha@redhat.com] > > > Sent: Thursday, December 9, 2021 5:17 PM > > > To: Longpeng (Mike, Cloud Infrastructure Service Product Dept.) > > > > > > Cc: jasowang@redhat.com; mst@redhat.com; parav@nvidia.com; > > > xieyongji@bytedance.com; sgarzare@redhat.com; Yechuan ; > > > Gonglei (Arei) ; qemu-devel@nongnu.org > > > Subject: Re: [RFC] vhost-vdpa-net: add vhost-vdpa-net host device support > > > > > > On Wed, Dec 08, 2021 at 01:20:10PM +0800, Longpeng(Mike) wrote: > > > > From: Longpeng > > > > > > > > Hi guys, > > > > > > > > This patch introduces vhost-vdpa-net device, which is inspired > > > > by vhost-user-blk and the proposal of vhost-vdpa-blk device [1]. > > > > > > > > I've tested this patch on Huawei's offload card: > > > > ./x86_64-softmmu/qemu-system-x86_64 \ > > > > -device vhost-vdpa-net-pci,vdpa-dev=/dev/vhost-vdpa-0 > > > > > > > > For virtio hardware offloading, the most important requirement for us > > > > is to support live migration between offloading cards from different > > > > vendors, the combination of netdev and virtio-net seems too heavy, we > > > > prefer a lightweight way. > > > > > > > > Maybe we could support both in the future ? Such as: > > > > > > > > * Lightweight > > > > Net: vhost-vdpa-net > > > > Storage: vhost-vdpa-blk > > > > > > > > * Heavy but more powerful > > > > Net: netdev + virtio-net + vhost-vdpa > > > > Storage: bdrv + virtio-blk + vhost-vdpa > > > > > > > > [1] https://www.mail-archive.com/qemu-devel@nongnu.org/msg797569.html > > > > > > Stefano presented a plan for vdpa-blk at KVM Forum 2021: > > > https://kvmforum2021.sched.com/event/ke3a/vdpa-blk-unified-hardware-and-sof > > > tware-offload-for-virtio-blk-stefano-garzarella-red-hat > > > > > > It's closer to today's virtio-net + vhost-net approach than the > > > vhost-vdpa-blk device you have mentioned. The idea is to treat vDPA as > > > an offload feature rather than a completely separate code path that > > > needs to be maintained and tested. That way QEMU's block layer features > > > and live migration work with vDPA devices and re-use the virtio-blk > > > code. The key functionality that has not been implemented yet is a "fast > > > path" mechanism that allows the QEMU virtio-blk device's virtqueue to be > > > offloaded to vDPA. > > > > > > The unified vdpa-blk architecture should deliver the same performance > > > as the vhost-vdpa-blk device you mentioned but with more features, so I > > > wonder what aspects of the vhost-vdpa-blk idea are important to you? > > > > > > QEMU already has vhost-user-blk, which takes a similar approach as the > > > vhost-vdpa-blk device you are proposing. I'm not against the > > > vhost-vdpa-blk approach in priciple, but would like to understand your > > > requirements and see if there is a way to collaborate on one vdpa-blk > > > implementation instead of dividing our efforts between two. > > > > > > > We prefer a simple way in the virtio hardware offloading case, it could reduce > > our maintenance workload, we no need to maintain the virtio-net, netdev, > > virtio-blk, bdrv and ... any more. If we need to support other vdpa devices > > (such as virtio-crypto, virtio-fs) in the future, then we also need to maintain > > the corresponding device emulation code? > > > > For the virtio hardware offloading case, we usually use the vfio-pci framework, > > it saves a lot of our maintenance work in QEMU, we don't need to touch the device > > types. Inspired by Jason, what we really prefer is "vhost-vdpa-pci/mmio", use it to > > instead of the vfio-pci, it could provide the same performance as vfio-pci, but it's > > *possible* to support live migrate between offloading cards from different vendors. > > OK, so the features you are dropping would be migration between > a vdpa, vhost and virtio backends. I think given vhost-vdpa-blk is seems > fair enough... What do others think? I think it should be fine, and it would be even better to make it not specific to device type. Thanks > > > > Stefan >