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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70CF1C77B6C for ; Thu, 13 Apr 2023 06:41:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229591AbjDMGlr (ORCPT ); Thu, 13 Apr 2023 02:41:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48862 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229876AbjDMGlj (ORCPT ); Thu, 13 Apr 2023 02:41:39 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFCF683FE for ; Wed, 12 Apr 2023 23:40:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681368050; 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=gpLT5R5/zK3cbjxkCACuzxBqVGqeFsHPUxNqi6hiv3s=; b=GF+F6+SXmlotNN14FvAjzyJwKeYvCpA7yOYCh+EJbaWfYxGxUbxgw8Vfyu5sVuLmWvAZDm 95G7iC3jZbt8sFfNPdJLBOx5lJad5Zvkl7kY52bNlQ36q0WnV+nJYSfeO1IHTciwcbzRJj DTPdOQ3Fe4rF9JceGvuDNix1V0f3B0I= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-152-BOUUWfWAONeJnvX6gK18fg-1; Thu, 13 Apr 2023 02:40:49 -0400 X-MC-Unique: BOUUWfWAONeJnvX6gK18fg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id AD9DE3C025B3; Thu, 13 Apr 2023 06:40:48 +0000 (UTC) Received: from localhost.localdomain (ovpn-12-72.pek2.redhat.com [10.72.12.72]) by smtp.corp.redhat.com (Postfix) with ESMTP id 20C6140C6F87; Thu, 13 Apr 2023 06:40:42 +0000 (UTC) From: Jason Wang To: mst@redhat.com, jasowang@redhat.com Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, maxime.coquelin@redhat.com, alvaro.karsz@solid-run.com, eperezma@redhat.com, xuanzhuo@linux.alibaba.com, david.marchand@redhat.com Subject: [PATCH net-next V2 2/2] virtio-net: sleep instead of busy waiting for cvq command Date: Thu, 13 Apr 2023 14:40:27 +0800 Message-Id: <20230413064027.13267-3-jasowang@redhat.com> In-Reply-To: <20230413064027.13267-1-jasowang@redhat.com> References: <20230413064027.13267-1-jasowang@redhat.com> MIME-Version: 1.0 Content-type: text/plain Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We used to busy waiting on the cvq command this tends to be problematic since there no way for to schedule another process which may serve for the control virtqueue. This might be the case when the control virtqueue is emulated by software. This patch switches to use completion to allow the CPU to sleep instead of busy waiting for the cvq command. Signed-off-by: Jason Wang --- Changes since V1: - use completion for simplicity - don't try to harden the CVQ command which requires more thought Changes since RFC: - break the device when timeout - get buffer manually since the virtio core check more_used() instead --- drivers/net/virtio_net.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 2e56bbf86894..d3eb8fd6c9dc 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -295,6 +296,8 @@ struct virtnet_info { /* failover when STANDBY feature enabled */ struct failover *failover; + + struct completion completion; }; struct padded_vnet_hdr { @@ -1709,6 +1712,13 @@ static bool try_fill_recv(struct virtnet_info *vi, struct receive_queue *rq, return !oom; } +static void virtnet_cvq_done(struct virtqueue *cvq) +{ + struct virtnet_info *vi = cvq->vdev->priv; + + complete(&vi->completion); +} + static void skb_recv_done(struct virtqueue *rvq) { struct virtnet_info *vi = rvq->vdev->priv; @@ -2169,12 +2179,8 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd, if (unlikely(!virtqueue_kick(vi->cvq))) return vi->ctrl->status == VIRTIO_NET_OK; - /* Spin for a response, the kick causes an ioport write, trapping - * into the hypervisor, so the request should be handled immediately. - */ - while (!virtqueue_get_buf(vi->cvq, &tmp) && - !virtqueue_is_broken(vi->cvq)) - cpu_relax(); + wait_for_completion(&vi->completion); + virtqueue_get_buf(vi->cvq, &tmp); return vi->ctrl->status == VIRTIO_NET_OK; } @@ -3672,7 +3678,7 @@ static int virtnet_find_vqs(struct virtnet_info *vi) /* Parameters for control virtqueue, if any */ if (vi->has_cvq) { - callbacks[total_vqs - 1] = NULL; + callbacks[total_vqs - 1] = virtnet_cvq_done; names[total_vqs - 1] = "control"; } @@ -4122,6 +4128,7 @@ static int virtnet_probe(struct virtio_device *vdev) if (vi->has_rss || vi->has_rss_hash_report) virtnet_init_default_rss(vi); + init_completion(&vi->completion); enable_rx_mode_work(vi); /* serialize netdev register + virtio_device_ready() with ndo_open() */ -- 2.25.1