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 6103BC64E7C for ; Wed, 2 Dec 2020 13:43:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DFB44205CB for ; Wed, 2 Dec 2020 13:43:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726477AbgLBNmx (ORCPT ); Wed, 2 Dec 2020 08:42:53 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:55009 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725955AbgLBNmu (ORCPT ); Wed, 2 Dec 2020 08:42:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606916483; 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=Vbxc9/ME5/SrQ1YXboDUD9984AjRX/c8zr65mwO3JWw=; b=EeWkGGphp3OoIS2BQwH75tNCxGlv9hGL1NtPbntT4uRre0tXN0gVSmF8LW3XOvaW3cAUGs AaGMMgpRNkiSJv0CGKW5y+KndxK6zj2mIieYS2Xcnw9BCzFMwzKvmvX1kCwwGloVo8ja0M oY38WOrZOmIKwiHFFJSeITPJOZxzrHY= 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-64-v0V9xy5ZPbCj-sdI41EOEQ-1; Wed, 02 Dec 2020 08:41:19 -0500 X-MC-Unique: v0V9xy5ZPbCj-sdI41EOEQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7322C106B6A3; Wed, 2 Dec 2020 13:41:17 +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 5C8395C22B; Wed, 2 Dec 2020 13:41:10 +0000 (UTC) Subject: Re: [PATCH] vdpa/mlx5: Use random MAC for the vdpa net instance To: "Michael S. Tsirkin" Cc: Cindy Lu , Eli Cohen , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <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> <20201202042328-mutt-send-email-mst@kernel.org> <128487fe-8736-6d9e-3d07-b55dcb92c9b0@redhat.com> <20201202080149-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: <692cfc1f-fb2d-1473-cc29-0231996de38d@redhat.com> Date: Wed, 2 Dec 2020 21:41:08 +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: <20201202080149-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 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/12/2 下午9:04, Michael S. Tsirkin wrote: > On Wed, Dec 02, 2020 at 08:56:37PM +0800, Jason Wang wrote: >> On 2020/12/2 下午5:30, Michael S. Tsirkin 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: >>>> >>>> 1) get a random mac >>> To me this looks like a spec violation. >>> >>> If the driver negotiates the VIRTIO_NET_F_MAC feature, the driver MUST set >>> the physical address of the NIC to \field{mac}. Otherwise, it SHOULD >>> use a locally-administered MAC address (see \hyperref[intro:IEEE 802]{IEEE 802}, >>> ``9.2 48-bit universal LAN MAC addresses''). >> >> One question here, what did "set" mean here consider the mac is given by the >> device itself? >> > > That is my understanding, and this seems to be what linux guests do. > >>> While not said explicitly, the assumption I think is that the local >>> MAC is not a local one. >>> >>> >>>> 2) advertise VIRTIO_NET_F_MAC >>>> 3) set the random mac to vDPA through set_config >>> that part looks wrong to me. Setting mac through set_config was >>> a pre-virtio-1.0 way to send mac to device. In 1.0 we have >>> VIRTIO_NET_CTRL_MAC_ADDR_SET for that: >>> >>> >>> When using the legacy interface, \field{mac} is driver-writable >>> which provided a way for drivers to update the MAC without >>> negotiating VIRTIO_NET_F_CTRL_MAC_ADDR. >> >> Looks like it doesn't prevent us from doing so. > From writing into mac? > Yes it does: > Device configuration fields are listed below, they are read-only for a driver. The \field{mac} address field > always exists (though is only valid if VIRTIO_NET_F_MAC is set), and > \field{status} only exists if VIRTIO_NET_F_STATUS is set. Okay, so this is a hint that the vDPA parent needs to check and ignore the write if version 1 is negotiated. > > >> Otherwise this brings an >> implicit dependency for control virtqueue if we want to support 1.0? >> >> Thanks > With 1.0 you either need VIRTIO_NET_F_CTRL_MAC_ADDR or VIRTIO_NET_F_MAC. > > Ok, so it looks to me VIRTIO_NET_F_MAC is the only choice for mlx5 consider control vq is not supported. Thanks >>> >>> >>>> 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