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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C89F5C77B72 for ; Thu, 20 Apr 2023 13:07:48 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ppU0M-0007Qs-Tf; Thu, 20 Apr 2023 09:07:18 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ppU0J-0007N4-8v for qemu-devel@nongnu.org; Thu, 20 Apr 2023 09:07:16 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ppU0G-0000Qw-Ba for qemu-devel@nongnu.org; Thu, 20 Apr 2023 09:07:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681996030; 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; bh=5wiVbdRlt+56no6bXVhuJBjqTPukz2YeJ7px0yVUNDo=; b=ULZg0guUHVXG/licVtuV9MnikScPNh6ht+Tby4HWkCRXnwqWcyGQyyWF6Jln4wFh3bqQJD OdcyQseVwKBsboR9a7C+Ahi0fzIQyPplEzwPXskha8Wap7suGyE8WEyk2IW7Nb3VXV5fYC 5HcPcW2GyZ+4QlzjD4Guz5tI3KPGjT8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-494-lOQfiRdvMt-e9eXYq-ElNA-1; Thu, 20 Apr 2023 09:07:08 -0400 X-MC-Unique: lOQfiRdvMt-e9eXYq-ElNA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1288D811E7B for ; Thu, 20 Apr 2023 13:07:08 +0000 (UTC) Received: from localhost (unknown [10.39.193.254]) by smtp.corp.redhat.com (Postfix) with ESMTP id 911A7440BC; Thu, 20 Apr 2023 13:07:07 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: "Michael S. Tsirkin" , Stefan Hajnoczi , Cindy Lu Subject: [PATCH] vhost-user: send SET_STATUS 0 after GET_VRING_BASE Date: Thu, 20 Apr 2023 09:07:06 -0400 Message-Id: <20230420130706.541219-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Setting the VIRTIO Device Status Field to 0 resets the device. The device's state is lost, including the vring configuration. vhost-user.c currently sends SET_STATUS 0 before GET_VRING_BASE. This risks confusion about the lifetime of the vhost-user state (e.g. vring last_avail_idx) across VIRTIO device reset. Eugenio Pérez adjusted the order for vhost-vdpa.c in commit c3716f260bff ("vdpa: move vhost reset after get vring base") and in that commit description suggested doing the same for vhost-user in the future. Go ahead and adjust vhost-user.c now. I ran various online code searches to identify vhost-user backends implementing SET_STATUS. It seems only DPDK implements SET_STATUS and Yajun Wu has confirmed that it is safe to make this change. Cc: Michael S. Tsirkin Cc: Cindy Lu Signed-off-by: Stefan Hajnoczi --- hw/virtio/vhost-user.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index e5285df4ba..2d40b1b3e7 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -2677,10 +2677,20 @@ static int vhost_user_dev_start(struct vhost_dev *dev, bool started) VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK); } else { - return vhost_user_set_status(dev, 0); + return 0; } } +static void vhost_user_reset_status(struct vhost_dev *dev) +{ + /* Set device status only for last queue pair */ + if (dev->vq_index + dev->nvqs != dev->vq_index_end) { + return; + } + + vhost_user_set_status(dev, 0); +} + const VhostOps user_ops = { .backend_type = VHOST_BACKEND_TYPE_USER, .vhost_backend_init = vhost_user_backend_init, @@ -2716,4 +2726,5 @@ const VhostOps user_ops = { .vhost_get_inflight_fd = vhost_user_get_inflight_fd, .vhost_set_inflight_fd = vhost_user_set_inflight_fd, .vhost_dev_start = vhost_user_dev_start, + .vhost_reset_status = vhost_user_reset_status, }; -- 2.39.2