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=-13.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,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 B452EC64E7B for ; Wed, 2 Dec 2020 13:50:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F9B42173E for ; Wed, 2 Dec 2020 13:50:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728071AbgLBNuF (ORCPT ); Wed, 2 Dec 2020 08:50:05 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:37091 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726023AbgLBNuE (ORCPT ); Wed, 2 Dec 2020 08:50:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606916917; 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=vHedmF2t1mThnVS41kBW1jt04b9cWe1xOcXAMd+DJ5o=; b=RV4A8yhDnB9db/iyH3LdLDYs1ZYyQFdWcbBWSWk8vw25U+AHaHRhLGom5CzX9ufywUu/qE eI5LAzyVBAvohyIFmrsPKTGEr6CxHzUR6ppanQkPcd4TDXE/l2MVAKMLDeGaOZ8RfvtIeA sgiQisdLBuecj7XooGSaKnNV3szSu70= 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-383-U_64aH1OPsKIZpMUDYYixA-1; Wed, 02 Dec 2020 08:48:33 -0500 X-MC-Unique: U_64aH1OPsKIZpMUDYYixA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 79CD31006C97; Wed, 2 Dec 2020 13:48:32 +0000 (UTC) Received: from [10.72.12.105] (ovpn-12-105.pek2.redhat.com [10.72.12.105]) by smtp.corp.redhat.com (Postfix) with ESMTP id DC9DD60BFA; Wed, 2 Dec 2020 13:48:26 +0000 (UTC) Subject: Re: [PATCH] vdpa/mlx5: Use random MAC for the vdpa net instance To: "Michael S. Tsirkin" , Eli Cohen Cc: Cindy Lu , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <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> <20201202055714.GA224423@mtl-vdi-166.wap.labs.mlnx> <20201202041518-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: <3e32ef6d-83c9-5866-30e5-f6eeacd5044d@redhat.com> Date: Wed, 2 Dec 2020 21:48:25 +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: <20201202041518-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/12/2 下午5:23, Michael S. Tsirkin wrote: > On Wed, Dec 02, 2020 at 07:57:14AM +0200, Eli Cohen wrote: >> On Wed, Dec 02, 2020 at 12:18:36PM +0800, Jason Wang wrote: >>> 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: >> Thinking it over, at least in mlx5, I should always advertise >> VIRTIO_NET_F_MAC and set a non zero MAC value. The source of the MAC can >> be either randomly generated value by mlx5_vdpa or by a management tool. >> This is important becauase we should not let the VM modify the MAC. If >> we do it can set a MAC value identical to the mlx5 NIC driver and can >> kidnap traffic that was not destined to it. >> >> In addition, when VIRTIO_NET_F_MAC is published, attempts to change the >> MAC address from the VM should result in error. > That is not what the spec says though. > VIRTIO_NET_F_MAC only says whether mac is valid in the config space. > Whether guest can control that depends on VIRTIO_NET_F_CTRL_MAC_ADDR: > > The VIRTIO_NET_CTRL_MAC_ADDR_SET command is used to set the default MAC address which rx > filtering accepts (and if VIRTIO_NET_F_MAC_ADDR has been negotiated, this will be reflected in mac in > config space). > The command-specific-data for VIRTIO_NET_CTRL_MAC_ADDR_SET is the 6-byte MAC address. Consider VIRTIO_NET_CTRL_MAC_ADDR_SET is not supported now. What Eli proposed here should work? Thanks > > > >