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=-18.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 7C395C64E8A for ; Wed, 2 Dec 2020 04:20:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1681A221FA for ; Wed, 2 Dec 2020 04:20:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728295AbgLBEUP (ORCPT ); Tue, 1 Dec 2020 23:20:15 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:26484 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728107AbgLBEUO (ORCPT ); Tue, 1 Dec 2020 23:20:14 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606882727; 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=VKLjGXRCIpjcgF67r8BnhprgVNy+jqChmRcBdfdwJYo=; b=Pgn9xxKNhDR2XE7w9KLyqDNkT/40sdr2v6Q5/T4TiX9q+5rTosbuPLtgOm0cuEKkyac4c6 Pe8pjNBGsjQ0IgIDju5z8oh8ULAQHlh9F5cidrUD+yDizy53/awDR1zM78CRxK0arq6cRL v+rIPK8PAQrcEGCPUl6oGpR9TLfeEBo= 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-16-pcG0PgjKOg6WDraIDaKtbA-1; Tue, 01 Dec 2020 23:18:43 -0500 X-MC-Unique: pcG0PgjKOg6WDraIDaKtbA-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id AE3AF8558E9; Wed, 2 Dec 2020 04:18:42 +0000 (UTC) Received: from [10.72.13.145] (ovpn-13-145.pek2.redhat.com [10.72.13.145]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7C4DF5D9DC; Wed, 2 Dec 2020 04:18:37 +0000 (UTC) Subject: Re: [PATCH] vdpa/mlx5: Use random MAC for the vdpa net instance To: Cindy Lu , "Michael S. Tsirkin" Cc: Eli Cohen , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20201129064351.63618-1-elic@nvidia.com> <20201129150505-mutt-send-email-mst@kernel.org> <20201130062746.GA99449@mtl-vdi-166.wap.labs.mlnx> <20201130035147-mutt-send-email-mst@kernel.org> <20201130092759.GB99449@mtl-vdi-166.wap.labs.mlnx> <20201130043050-mutt-send-email-mst@kernel.org> <20201130103142-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: Date: Wed, 2 Dec 2020 12:18:36 +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: 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/12/1 下午5:23, Cindy Lu wrote: > On Mon, Nov 30, 2020 at 11:33 PM Michael S. Tsirkin wrote: >> On Mon, Nov 30, 2020 at 06:41:45PM +0800, Cindy Lu wrote: >>> On Mon, Nov 30, 2020 at 5:33 PM Michael S. Tsirkin wrote: >>>> On Mon, Nov 30, 2020 at 11:27:59AM +0200, Eli Cohen wrote: >>>>> On Mon, Nov 30, 2020 at 04:00:51AM -0500, Michael S. Tsirkin wrote: >>>>>> On Mon, Nov 30, 2020 at 08:27:46AM +0200, Eli Cohen wrote: >>>>>>> On Sun, Nov 29, 2020 at 03:08:22PM -0500, Michael S. Tsirkin wrote: >>>>>>>> On Sun, Nov 29, 2020 at 08:43:51AM +0200, Eli Cohen wrote: >>>>>>>>> We should not try to use the VF MAC address as that is used by the >>>>>>>>> regular (e.g. mlx5_core) NIC implementation. Instead, use a random >>>>>>>>> generated MAC address. >>>>>>>>> >>>>>>>>> Suggested by: Cindy Lu >>>>>>>>> Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices") >>>>>>>>> Signed-off-by: Eli Cohen >>>>>>>> I didn't realise it's possible to use VF in two ways >>>>>>>> with and without vdpa. >>>>>>> Using a VF you can create quite a few resources, e.g. send queues >>>>>>> recieve queues, virtio_net queues etc. So you can possibly create >>>>>>> several instances of vdpa net devices and nic net devices. >>>>>>> >>>>>>>> Could you include a bit more description on the failure >>>>>>>> mode? >>>>>>> Well, using the MAC address of the nic vport is wrong since that is the >>>>>>> MAC of the regular NIC implementation of mlx5_core. >>>>>> Right but ATM it doesn't coexist with vdpa so what's the problem? >>>>>> >>>>> This call is wrong: mlx5_query_nic_vport_mac_address() >>>>> >>>>>>>> Is switching to a random mac for such an unusual >>>>>>>> configuration really justified? >>>>>>> Since I can't use the NIC's MAC address, I have two options: >>>>>>> 1. To get the MAC address as was chosen by the user administering the >>>>>>> NIC. This should invoke the set_config callback. Unfortunately this >>>>>>> is not implemented yet. >>>>>>> >>>>>>> 2. Use a random MAC address. This is OK since if (1) is implemented it >>>>>>> can always override this random configuration. >>>>>>> >>>>>>>> It looks like changing a MAC could break some guests, >>>>>>>> can it not? >>>>>>>> >>>>>>> No, it will not. The current version of mlx5 VDPA does not allow regular >>>>>>> NIC driver and VDPA to co-exist. I have patches ready that enable that >>>>>>> from steering point of view. I will post them here once other patches on >>>>>>> which they depend will be merged. >>>>>>> >>>>>>> https://patchwork.ozlabs.org/project/netdev/patch/20201120230339.651609-12-saeedm@nvidia.com/ >>>>>> Could you be more explicit on the following points: >>>>>> - which configuration is broken ATM (as in, two device have identical >>>>>> macs? any other issues)? >>>>> The only wrong thing is the call to mlx5_query_nic_vport_mac_address(). >>>>> It's not breaking anything yet is wrong. The random MAC address setting >>>>> is required for the steering patches. >>>> Okay so I'm not sure the Fixes tag at least is appropriate if it's a >>>> dependency of a new feature. >>>> >>>>>> - why won't device MAC change from guest point of view? >>>>>> >>>>> It's lack of implementation in qemu as far as I know. >>>> Sorry not sure I understand. What's not implemented in QEMU? >>>> >>> HI Michael, there are some bug in qemu to set_config, this will fix in future, >>> But this patch is still needed, because without this patch the mlx >>> driver will give an 0 mac address to qemu >>> and qemu will overwrite the default mac address. This will cause traffic down. >> Hmm the patch description says VF mac address, not 0 address. Confused. >> If there's no mac we can clear VIRTIO_NET_F_MAC and have guest >> use a random value ... I'm not sure this can work for all types of vDPA (e.g it could not be a learning bridge in the swtich). >> > hi Michael， > I have tried as your suggestion, seems even remove the > VIRTIO_NET_F_MAC the qemu will still call get_cinfig and overwrite the > default address in VM, This looks a bug in qemu, in guest driver we had:     /* Configuration may specify what MAC to use.  Otherwise random. */     if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC))         virtio_cread_bytes(vdev,                    offsetof(struct virtio_net_config, mac),                    dev->dev_addr, dev->addr_len);     else         eth_hw_addr_random(dev); > this process is like > vdpa _init -->qemu call get_config ->mlx driver will give an mac > address with all 0--> > qemu will not check this mac address and use it --> overwrite the mac > address in qemu > > So for my understanding there are several method to fix this problem > > 1, qemu check the mac address, if the mac address is all 0, qemu will > ignore it and set the random mac address to mlx driver. So my understanding is that, if mac address is all 0, vDPA parent should not advertise VIRTIO_NET_F_MAC. And qemu should emulate this feature as you did: 1) get a random mac 2) advertise VIRTIO_NET_F_MAC 3) set the random mac to vDPA through set_config 4) advertise the random mac to emulated config to guest > 2. mlx driver checks the mac address and if this mac is 0, return fail > to qemu, but this need to change the UAPI. uAPI is probably fine since ioctl can fail.  We can change the to allow the set_config to fail but virito spec doesn't have a way to advertise the error in this case. Anyway, the driver only risk itself for setting a wrong value, so we're probably fine. Thanks > 3. mlx driver it shelf should get an correct mac address while it init. > 4. add check in qemu get_config function , if there is not F_MAC Then > ignore the mac address from mlx driver > > not sure which method is more suitable ? > > Thanks > Cindy > > > >>>>>>>>> --- >>>>>>>>> drivers/vdpa/mlx5/net/mlx5_vnet.c | 5 +---- >>>>>>>>> 1 file changed, 1 insertion(+), 4 deletions(-) >>>>>>>>> >>>>>>>>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c >>>>>>>>> index 1fa6fcac8299..80d06d958b8b 100644 >>>>>>>>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c >>>>>>>>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c >>>>>>>>> @@ -1955,10 +1955,7 @@ void *mlx5_vdpa_add_dev(struct mlx5_core_dev *mdev) >>>>>>>>> if (err) >>>>>>>>> goto err_mtu; >>>>>>>>> >>>>>>>>> - err = mlx5_query_nic_vport_mac_address(mdev, 0, 0, config->mac); >>>>>>>>> - if (err) >>>>>>>>> - goto err_mtu; >>>>>>>>> - >>>>>>>>> + eth_random_addr(config->mac); >>>>>>>>> mvdev->vdev.dma_dev = mdev->device; >>>>>>>>> err = mlx5_vdpa_alloc_resources(&ndev->mvdev); >>>>>>>>> if (err) >>>>>>>>> -- >>>>>>>>> 2.26.2