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 B7249C4332F for ; Tue, 27 Dec 2022 02:25:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232529AbiL0CZL (ORCPT ); Mon, 26 Dec 2022 21:25:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231703AbiL0CZG (ORCPT ); Mon, 26 Dec 2022 21:25:06 -0500 Received: from out30-43.freemail.mail.aliyun.com (out30-43.freemail.mail.aliyun.com [115.124.30.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 11E64266C; Mon, 26 Dec 2022 18:25:03 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R691e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046050;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0VYBb5xz_1672107900; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0VYBb5xz_1672107900) by smtp.aliyun-inc.com; Tue, 27 Dec 2022 10:25:00 +0800 Message-ID: <1672107557.0142956-1-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH 4/4] virtio-net: sleep instead of busy waiting for cvq command Date: Tue, 27 Dec 2022 10:19:17 +0800 From: Xuan Zhuo To: Jason Wang Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, eperezma@redhat.com, edumazet@google.com, maxime.coquelin@redhat.com, kuba@kernel.org, pabeni@redhat.com, davem@davemloft.net, mst@redhat.com, jasowang@redhat.com References: <20221226074908.8154-1-jasowang@redhat.com> <20221226074908.8154-5-jasowang@redhat.com> In-Reply-To: <20221226074908.8154-5-jasowang@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 26 Dec 2022 15:49:08 +0800, Jason Wang wrote: > We used to busy waiting on the cvq command this tends to be > problematic since: > > 1) CPU could wait for ever on a buggy/malicous device > 2) There's no wait to terminate the process that triggers the cvq > command > > So this patch switch to use virtqueue_wait_for_used() to sleep with a > timeout (1s) instead of busy polling for the cvq command forever. This I don't think that a fixed 1S is a good choice. Some of the DPUs are very lazy for cvq handle. In particular, we will also directly break the device. I think it is necessary to add a Virtio-Net parameter to allow users to define this timeout by themselves. Although I don't think this is a good way. Thanks. > gives the scheduler a breath and can let the process can respond to > asignal. If the device doesn't respond in the timeout, break the > device. > > Signed-off-by: Jason Wang > --- > Changes since V1: > - break the device when timeout > - get buffer manually since the virtio core check more_used() instead > --- > drivers/net/virtio_net.c | 24 ++++++++++++++++-------- > 1 file changed, 16 insertions(+), 8 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index efd9dd55828b..6a2ea64cfcb5 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -405,6 +405,7 @@ static void disable_rx_mode_work(struct virtnet_info *vi) > vi->rx_mode_work_enabled = false; > spin_unlock_bh(&vi->rx_mode_lock); > > + virtqueue_wake_up(vi->cvq); > flush_work(&vi->rx_mode_work); > } > > @@ -1497,6 +1498,11 @@ static bool try_fill_recv(struct virtnet_info *vi, struct receive_queue *rq, > return !oom; > } > > +static void virtnet_cvq_done(struct virtqueue *cvq) > +{ > + virtqueue_wake_up(cvq); > +} > + > static void skb_recv_done(struct virtqueue *rvq) > { > struct virtnet_info *vi = rvq->vdev->priv; > @@ -1984,6 +1990,8 @@ static int virtnet_tx_resize(struct virtnet_info *vi, > return err; > } > > +static int virtnet_close(struct net_device *dev); > + > /* > * Send command via the control virtqueue and check status. Commands > * supported by the hypervisor, as indicated by feature bits, should > @@ -2026,14 +2034,14 @@ 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(); > + if (virtqueue_wait_for_used(vi->cvq)) { > + virtqueue_get_buf(vi->cvq, &tmp); > + return vi->ctrl->status == VIRTIO_NET_OK; > + } > > - return vi->ctrl->status == VIRTIO_NET_OK; > + netdev_err(vi->dev, "CVQ command timeout, break the virtio device."); > + virtio_break_device(vi->vdev); > + return VIRTIO_NET_ERR; > } > > static int virtnet_set_mac_address(struct net_device *dev, void *p) > @@ -3526,7 +3534,7 @@ 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"; > } > > -- > 2.25.1 > > _______________________________________________ > Virtualization mailing list > Virtualization@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/virtualization