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=-17.8 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,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 0BDABC433DB for ; Mon, 8 Feb 2021 04:39:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CC68D64E66 for ; Mon, 8 Feb 2021 04:39:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229719AbhBHEjF (ORCPT ); Sun, 7 Feb 2021 23:39:05 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:31918 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229587AbhBHEjA (ORCPT ); Sun, 7 Feb 2021 23:39:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612759054; 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=AXyJJxjVxwqQYUGq8cjXowIkJ5w7ooor07ZQr4A7YuY=; b=DKoyP3hD3h7y0/ZKU7vHPen+rVClgp04DKMYJ0PegFqfThrSz9Duqc+VIM1ieG4ZVQyx5b bBIkXkhn4SRVdEw4xJt2Jnb1hKFe69VcSY3AxKT13SA9RWwtJJxKmRCBt12FUKgq671E62 nSJkNgb7MI7dXAaGDDxdzGlcvZU0ewA= 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-550-1ibjxQD5NdS8YIl3FSaJFw-1; Sun, 07 Feb 2021 23:37:32 -0500 X-MC-Unique: 1ibjxQD5NdS8YIl3FSaJFw-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 32416192D786; Mon, 8 Feb 2021 04:37:31 +0000 (UTC) Received: from [10.72.13.185] (ovpn-13-185.pek2.redhat.com [10.72.13.185]) by smtp.corp.redhat.com (Postfix) with ESMTP id 436F05C1C2; Mon, 8 Feb 2021 04:37:25 +0000 (UTC) Subject: Re: [PATCH 2/3] mlx5_vdpa: fix feature negotiation across device reset To: Si-Wei Liu , mst@redhat.com, elic@nvidia.com Cc: linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org References: <1612614564-4220-1-git-send-email-si-wei.liu@oracle.com> <1612614564-4220-2-git-send-email-si-wei.liu@oracle.com> From: Jason Wang Message-ID: <4d6b8fc7-e697-d027-7763-8e56e0669a31@redhat.com> Date: Mon, 8 Feb 2021 12:37:24 +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: <1612614564-4220-2-git-send-email-si-wei.liu@oracle.com> 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 2021/2/6 下午8:29, Si-Wei Liu wrote: > The mlx_features denotes the capability for which > set of virtio features is supported by device. In > principle, this field needs not be cleared during > virtio device reset, as this capability is static > and does not change across reset. > > In fact, the current code may have the assumption > that mlx_features can be reloaded from firmware > via the .get_features ops after device is reset > (via the .set_status ops), which is unfortunately > not true. The userspace VMM might save a copy > of backend capable features and won't call into > kernel again to get it on reset. This is not the behavior of Qemu but it's valid. > This causes all > virtio features getting disabled on newly created > virtqs after device reset, while guest would hold > mismatched view of available features. For e.g., > the guest may still assume tx checksum offload > is available after reset and feature negotiation, > causing frames with bogus (incomplete) checksum > transmitted on the wire. > > Signed-off-by: Si-Wei Liu Acked-by: Jason Wang > --- > drivers/vdpa/mlx5/net/mlx5_vnet.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c > index b8416c4..aa6f8cd 100644 > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c > @@ -1788,7 +1788,6 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status) > clear_virtqueues(ndev); > mlx5_vdpa_destroy_mr(&ndev->mvdev); > ndev->mvdev.status = 0; > - ndev->mvdev.mlx_features = 0; > ++mvdev->generation; > return; > }