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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 41D24CA9EB7 for ; Mon, 21 Oct 2019 10:13:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F4F720684 for ; Mon, 21 Oct 2019 10:13:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VzqovNX1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727874AbfJUKNo (ORCPT ); Mon, 21 Oct 2019 06:13:44 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:22461 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726725AbfJUKNn (ORCPT ); Mon, 21 Oct 2019 06:13:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1571652822; 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=X10UFs7tuPUPd3D+40Rh0JtzksdyNoor8tHqygg664s=; b=VzqovNX1kVyNEwPu5L4CM2VOP8igO0KlQYVs3lnk4BhYL26zxXUVbVBKMCHB0dLvuwWFGa kUjeqO3cT1wqtG86g5HYOt+qxEdBbokRKINfA2KmLI4lTx2ZLEIzF/ozdAnXtlYwyBUUAl FFpb4zmKpPfk/X9jNeuCIQVPVcHcAv4= 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-151-L7NxpIXqPOmlWs4WJm5E6w-1; Mon, 21 Oct 2019 06:13:38 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DE1ED800D49; Mon, 21 Oct 2019 10:13:34 +0000 (UTC) Received: from [10.72.12.22] (ovpn-12-22.pek2.redhat.com [10.72.12.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3A0AB5D70E; Mon, 21 Oct 2019 10:13:03 +0000 (UTC) Subject: Re: [PATCH V4 5/6] virtio: introduce a mdev based transport To: Cornelia Huck Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, kwankhede@nvidia.com, alex.williamson@redhat.com, mst@redhat.com, tiwei.bie@intel.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, maxime.coquelin@redhat.com, cunming.liang@intel.com, zhihong.wang@intel.com, rob.miller@broadcom.com, xiao.w.wang@intel.com, haotian.wang@sifive.com, zhenyuw@linux.intel.com, zhi.a.wang@intel.com, jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com, airlied@linux.ie, daniel@ffwll.ch, farman@linux.ibm.com, pasic@linux.ibm.com, sebott@linux.ibm.com, oberpar@linux.ibm.com, heiko.carstens@de.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, akrowiak@linux.ibm.com, freude@linux.ibm.com, lingshan.zhu@intel.com, idos@mellanox.com, eperezma@redhat.com, lulu@redhat.com, parav@mellanox.com, christophe.de.dinechin@gmail.com, kevin.tian@intel.com, stefanha@redhat.com References: <20191017104836.32464-1-jasowang@redhat.com> <20191017104836.32464-6-jasowang@redhat.com> <20191018162007.31631039.cohuck@redhat.com> <2bb5645b-5c46-9cae-0571-65c302f51cf2@redhat.com> <20191021113607.16b26d9d.cohuck@redhat.com> From: Jason Wang Message-ID: <1aa59fea-cae5-6303-4a94-51493d5748ba@redhat.com> Date: Mon, 21 Oct 2019 18:13:02 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191021113607.16b26d9d.cohuck@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: L7NxpIXqPOmlWs4WJm5E6w-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2019/10/21 =E4=B8=8B=E5=8D=885:36, Cornelia Huck wrote: > On Mon, 21 Oct 2019 13:59:23 +0800 > Jason Wang wrote: > >> On 2019/10/18 =E4=B8=8B=E5=8D=8810:20, Cornelia Huck wrote: >>> On Thu, 17 Oct 2019 18:48:35 +0800 >>> Jason Wang wrote: >>> =20 >>>> This patch introduces a new mdev transport for virtio. This is used to >>>> use kernel virtio driver to drive the mediated device that is capable >>>> of populating virtqueue directly. >>>> >>>> A new virtio-mdev driver will be registered to the mdev bus, when a >>>> new virtio-mdev device is probed, it will register the device with >>>> mdev based config ops. This means it is a software transport between >>>> mdev driver and mdev device. The transport was implemented through >>>> device specific ops which is a part of mdev_parent_ops now. >>>> >>>> Signed-off-by: Jason Wang >>>> --- >>>> drivers/virtio/Kconfig | 7 + >>>> drivers/virtio/Makefile | 1 + >>>> drivers/virtio/virtio_mdev.c | 409 ++++++++++++++++++++++++++++++++= +++ >>>> 3 files changed, 417 insertions(+) >>> (...) >>> =20 >>>> +static int virtio_mdev_probe(struct device *dev) >>>> +{ >>>> +=09struct mdev_device *mdev =3D mdev_from_dev(dev); >>>> +=09const struct virtio_mdev_device_ops *ops =3D mdev_get_dev_ops(mdev= ); >>>> +=09struct virtio_mdev_device *vm_dev; >>>> +=09int rc; >>>> + >>>> +=09vm_dev =3D devm_kzalloc(dev, sizeof(*vm_dev), GFP_KERNEL); >>>> +=09if (!vm_dev) >>>> +=09=09return -ENOMEM; >>>> + >>>> +=09vm_dev->vdev.dev.parent =3D dev; >>>> +=09vm_dev->vdev.dev.release =3D virtio_mdev_release_dev; >>>> +=09vm_dev->vdev.config =3D &virtio_mdev_config_ops; >>>> +=09vm_dev->mdev =3D mdev; >>>> +=09INIT_LIST_HEAD(&vm_dev->virtqueues); >>>> +=09spin_lock_init(&vm_dev->lock); >>>> + >>>> +=09vm_dev->version =3D ops->get_mdev_features(mdev); >>>> +=09if (vm_dev->version !=3D VIRTIO_MDEV_F_VERSION_1) { >>>> +=09=09dev_err(dev, "VIRTIO_MDEV_F_VERSION_1 is mandatory\n"); >>>> +=09=09return -ENXIO; >>>> +=09} >>> Hm, so how is that mdev features interface supposed to work? If >>> VIRTIO_MDEV_F_VERSION_1 is a bit, I would expect this code to test for >>> its presence, and not for identity. >> >> This should be used by driver to detect the which sets of functions and >> their semantics that could be provided by the device. E.g when driver >> support both version 2 and version 1 but device only support version 1, >> driver can switch to use version 1. Btw, Is there a easy way for to test >> its presence or do you mean doing sanity testing on existence of the >> mandatory ops that provided by the device? > What I meant was something like: > > features =3D ops->get_mdev_features(mdev); > if (features & VIRTIO_MDEV_F_VERSION_1) > =09vm_dev->version =3D 1; > else > =09//moan about missing support for version 1 > > Can there be class id specific extra features, or is this only for core > features? If the latter, maybe also do something like > > supported_features =3D ORED_LIST_OF_FEATURES; > if (features & ~supported_features) > =09//moan about extra feature bits Consider driver can claim to support a list of ids, so I this it's former. Will do as what you proposed. Thanks > >> >>> What will happen if we come up with a version 2? If this is backwards >>> compatible, will both version 2 and version 1 be set? >> >> Yes, I think so, and version 2 should be considered as some extensions >> of version 1. If it's completely, it should use a new class id. > Ok, that makes sense. >