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=-17.6 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=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 93EC8C433E0 for ; Tue, 2 Feb 2021 03:14:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D39C64EDD for ; Tue, 2 Feb 2021 03:14:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231264AbhBBDOg (ORCPT ); Mon, 1 Feb 2021 22:14:36 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:23560 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231158AbhBBDOf (ORCPT ); Mon, 1 Feb 2021 22:14:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612235584; 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=kUWFN4ekNdpi4WxcUqZD8X9JUjgbpEhAfA6K+mxCnDM=; b=RLyef//RASzBIdUap2YcepjW5QNuNC+p7cB0W47Y69as0hrnS4yU8lCeo5Q8lKKI0EMxo5 22ib9AB5V+Ezdebz1ljnAQ8DzpGgHV0DblXKmqroOY9Vfj3p7L9YbUQkoZGbtYNhRmTfoe n4dbVVZj6qWK2hSbC5VkFJLM5i1bb5g= 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-328-Xm7YpHbfPKGCCPIAwAzINg-1; Mon, 01 Feb 2021 22:13:01 -0500 X-MC-Unique: Xm7YpHbfPKGCCPIAwAzINg-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 C5B4C800D53; Tue, 2 Feb 2021 03:12:59 +0000 (UTC) Received: from [10.72.13.250] (ovpn-13-250.pek2.redhat.com [10.72.13.250]) by smtp.corp.redhat.com (Postfix) with ESMTP id 80C2360BE5; Tue, 2 Feb 2021 03:12:54 +0000 (UTC) Subject: Re: [PATCH 1/2] vdpa/mlx5: Avoid unnecessary query virtqueue To: Si-Wei Liu , Eli Cohen Cc: mst@redhat.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, lulu@redhat.com, Si-Wei Liu References: <20210128134130.3051-1-elic@nvidia.com> <20210128134130.3051-2-elic@nvidia.com> From: Jason Wang Message-ID: <9d6058d6-5ce1-0442-8fd9-5a6fe6a0bc6b@redhat.com> Date: Tue, 2 Feb 2021 11:12:51 +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 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2021/2/2 上午3:17, Si-Wei Liu wrote: > On Mon, Feb 1, 2021 at 10:51 AM Si-Wei Liu wrote: >> On Thu, Jan 28, 2021 at 5:46 AM Eli Cohen wrote: >>> suspend_vq should only suspend the VQ on not save the current available >>> index. This is done when a change of map occurs when the driver calls >>> save_channel_info(). >> Hmmm, suspend_vq() is also called by teardown_vq(), the latter of >> which doesn't save the available index as save_channel_info() doesn't >> get called in that path at all. How does it handle the case that >> aget_vq_state() is called from userspace (e.g. QEMU) while the >> hardware VQ object was torn down, but userspace still wants to access >> the queue index? >> >> Refer to https://lore.kernel.org/netdev/1601583511-15138-1-git-send-email-si-wei.liu@oracle.com/ >> >> vhost VQ 0 ring restore failed: -1: Resource temporarily unavailable (11) >> vhost VQ 1 ring restore failed: -1: Resource temporarily unavailable (11) >> >> QEMU will complain with the above warning while VM is being rebooted >> or shut down. >> >> Looks to me either the kernel driver should cover this requirement, or >> the userspace has to bear the burden in saving the index and not call >> into kernel if VQ is destroyed. > Actually, the userspace doesn't have the insights whether virt queue > will be destroyed if just changing the device status via set_status(). > Looking at other vdpa driver in tree i.e. ifcvf it doesn't behave like > so. Hence this still looks to me to be Mellanox specifics and > mlx5_vdpa implementation detail that shouldn't expose to userspace. So I think we can simply drop this patch? Thanks >> -Siwei >> >> >>> Signed-off-by: Eli Cohen >>> --- >>> drivers/vdpa/mlx5/net/mlx5_vnet.c | 8 -------- >>> 1 file changed, 8 deletions(-) >>> >>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c >>> index 88dde3455bfd..549ded074ff3 100644 >>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c >>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c >>> @@ -1148,8 +1148,6 @@ static int setup_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq) >>> >>> static void suspend_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq) >>> { >>> - struct mlx5_virtq_attr attr; >>> - >>> if (!mvq->initialized) >>> return; >>> >>> @@ -1158,12 +1156,6 @@ static void suspend_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *m >>> >>> if (modify_virtqueue(ndev, mvq, MLX5_VIRTIO_NET_Q_OBJECT_STATE_SUSPEND)) >>> mlx5_vdpa_warn(&ndev->mvdev, "modify to suspend failed\n"); >>> - >>> - if (query_virtqueue(ndev, mvq, &attr)) { >>> - mlx5_vdpa_warn(&ndev->mvdev, "failed to query virtqueue\n"); >>> - return; >>> - } >>> - mvq->avail_idx = attr.available_index; >>> } >>> >>> static void suspend_vqs(struct mlx5_vdpa_net *ndev) >>> -- >>> 2.29.2 >>>