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=-5.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 D663CC433DF for ; Mon, 20 Jul 2020 04:13:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A929520709 for ; Mon, 20 Jul 2020 04:13:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fZX1q3PQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725878AbgGTEMp (ORCPT ); Mon, 20 Jul 2020 00:12:45 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:30214 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725287AbgGTEMp (ORCPT ); Mon, 20 Jul 2020 00:12:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595218363; 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=jNmYyatHBjazXta2G+8f7FUFOpNtqCLp5w3UofyHTXI=; b=fZX1q3PQ70EQT9bQdOCgmg3nvfoe2cHXLt7AK5QmKq7ZXm7LB4alrfh2Q9YZI1twS+erUM lOTpyNsc+sB9ROMAWEglzGbYgZF4Pm0DdlVnc6oz+hmH0d5IRwxfrrLCCsX+9DU9QED3Em WfV9auKOocoVGgoMw8JY1KH4myuSq64= 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-148-vz456LNhO_qCuug1rjUAMQ-1; Mon, 20 Jul 2020 00:12:39 -0400 X-MC-Unique: vz456LNhO_qCuug1rjUAMQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D803318A1DE1; Mon, 20 Jul 2020 04:12:37 +0000 (UTC) Received: from [10.72.13.139] (ovpn-13-139.pek2.redhat.com [10.72.13.139]) by smtp.corp.redhat.com (Postfix) with ESMTP id 69EAA72E52; Mon, 20 Jul 2020 04:12:32 +0000 (UTC) Subject: Re: [PATCH vhost next 10/10] vdpa/mlx5: Add VDPA driver for supported mlx5 devices To: Eli Cohen Cc: mst@redhat.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, shahafs@mellanox.com, saeedm@mellanox.com, Parav Pandit , Eugenio Perez Martin References: <20200716072327.5359-1-eli@mellanox.com> <20200716072327.5359-11-eli@mellanox.com> <454850cc-269b-72aa-4511-2bf793a215cc@redhat.com> <20200716115428.GC186790@mtl-vdi-166.wap.labs.mlnx> <20200718194902.GA52765@mtl-vdi-166.wap.labs.mlnx> From: Jason Wang Message-ID: Date: Mon, 20 Jul 2020 12:12:30 +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: <20200718194902.GA52765@mtl-vdi-166.wap.labs.mlnx> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/7/19 上午3:49, Eli Cohen wrote: > On Fri, Jul 17, 2020 at 04:57:29PM +0800, Jason Wang wrote: >>> Looks like checking intialized is enough. Will fix this. >>>>> + >>>>> +static void mlx5_vdpa_set_vq_ready(struct vdpa_device *vdev, u16 idx, bool ready) >>>>> +{ >>>>> + struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev); >>>>> + struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev); >>>>> + struct mlx5_vdpa_virtqueue *mvq = &ndev->vqs[idx]; >>>>> + int err; >>>>> + >>>>> + if (!mvq->ready && ready && mvq->fw_state != MLX5_VIRTIO_NET_Q_OBJECT_STATE_RDY) { >>>>> + err = modify_virtqueue(ndev, mvq, MLX5_VIRTIO_NET_Q_OBJECT_STATE_RDY); >>>>> + if (err) { >>>>> + mlx5_vdpa_warn(mvdev, "failed to modify virtqueue(%d)\n", err); >>>>> + return; >>>>> + } >>>>> + } >>>> I wonder what's the reason of changing vq state on the hardware >>>> here. I think we can defer it to set_status(). >>>> >>> I can defer this to set status. >>> >>> I just wonder if it is possible that the core vdpa driver may call this >>> function with ready equals false and after some time call it with ready >>> equals true. >> >> Good point, so I think we can keep the logic. But looks like the >> code can not work if ready equals false since it only tries to >> modify vq state to RDY. >> > The point is that you cannot modify the virtqueue to "not ready". Is this a hardware limitation of software one? I'm asking since we need support live migration. But a questions is how to stop the device but not reset, since we need get e.g last_avail_idx from the device. It could be either: 1) set_status(0) 2) get_vq_state() or 1) set_queue_ready(0) 2) get_vq_state() Set_status(0) means reset the virtio device but last_avail_idx is something out of virtio spec. I guess using set_queue_ready() is better. What's you opinion? Thanks > The > only option is to destroy it and create a new one. This means that if I > get ready equals false after the virtqueue has been created I need to > teardown the driver and set it up again. > > Given that, I think your original suggestion to defer this logic is > reasonable. >