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 E30B0C3DA7C for ; Thu, 29 Dec 2022 02:06:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232895AbiL2CGU (ORCPT ); Wed, 28 Dec 2022 21:06:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42580 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230083AbiL2CGQ (ORCPT ); Wed, 28 Dec 2022 21:06:16 -0500 Received: from out30-45.freemail.mail.aliyun.com (out30-45.freemail.mail.aliyun.com [115.124.30.45]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 43393194; Wed, 28 Dec 2022 18:06:14 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046059;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0VYJPPK2_1672279570; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0VYJPPK2_1672279570) by smtp.aliyun-inc.com; Thu, 29 Dec 2022 10:06:11 +0800 Message-ID: <1672279315.3435805-1-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH 4/4] virtio-net: sleep instead of busy waiting for cvq command Date: Thu, 29 Dec 2022 10:01:55 +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 References: <20221226074908.8154-1-jasowang@redhat.com> <20221226074908.8154-5-jasowang@redhat.com> <1672107557.0142956-1-xuanzhuo@linux.alibaba.com> <1672216748.7057884-1-xuanzhuo@linux.alibaba.com> In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 28 Dec 2022 19:43:56 +0800, Jason Wang wrote: > On Wed, Dec 28, 2022 at 4:40 PM Xuan Zhuo wrote: > > > > On Tue, 27 Dec 2022 12:33:53 +0800, Jason Wang wrote: > > > On Tue, Dec 27, 2022 at 10:25 AM Xuan Zhuo wrote: > > > > > > > > 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. > > > > > > Well, it could be tweaked to be a little bit longer. > > > > > > One way, as discussed, is to let the device advertise a timeout then > > > the driver can validate if it's valid and use that timeout. But it > > > needs extension to the spec. > > > > > > > Some of the DPUs are very > > > > lazy for cvq handle. > > > > > > Such design needs to be revisited, cvq (control path) should have a > > > better priority or QOS than datapath. > > > > > > > In particular, we will also directly break the device. > > > > > > It's kind of hardening for malicious devices. > > > > Just based on timeout, it is judged that it is a malicious device. I think it is > > too arbitrary. > > Drivers have very little information to make the decision. So it's > really a balance. > > We can start with a very long timeout like 10 minutes. Otherwise a > buggy/malicious device will block a lot of important things (reboot, > modprobe) even if the scheduler is still functional. Relatively speaking, starting from a 1min+ timeout, I think it is safe. Thanks. > > Thanks > > > > > Thanks. > > > > > > > > > > > > > > > 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. > > > > > > Very hard and unfriendly to the end users. > > > > > > Thanks > > > > > > > > > > > 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 > > > > > > > > > > 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 smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 8E73CC4332F for ; Thu, 29 Dec 2022 02:06:24 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id EB0D84011D; Thu, 29 Dec 2022 02:06:23 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org EB0D84011D X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id eyjT-WbOi7ke; 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Thu, 29 Dec 2022 02:06:17 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org 37A5B6066D Received: from out30-44.freemail.mail.aliyun.com (out30-44.freemail.mail.aliyun.com [115.124.30.44]) by smtp3.osuosl.org (Postfix) with ESMTPS id 37A5B6066D for ; Thu, 29 Dec 2022 02:06:16 +0000 (UTC) X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R141e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=ay29a033018046059; MF=xuanzhuo@linux.alibaba.com; NM=1; PH=DS; RN=11; SR=0; TI=SMTPD_---0VYJPPK2_1672279570; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0VYJPPK2_1672279570) by smtp.aliyun-inc.com; Thu, 29 Dec 2022 10:06:11 +0800 Message-ID: <1672279315.3435805-1-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH 4/4] virtio-net: sleep instead of busy waiting for cvq command Date: Thu, 29 Dec 2022 10:01:55 +0800 From: Xuan Zhuo To: Jason Wang References: <20221226074908.8154-1-jasowang@redhat.com> <20221226074908.8154-5-jasowang@redhat.com> <1672107557.0142956-1-xuanzhuo@linux.alibaba.com> <1672216748.7057884-1-xuanzhuo@linux.alibaba.com> In-Reply-To: Cc: mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, eperezma@redhat.com, edumazet@google.com, kuba@kernel.org, maxime.coquelin@redhat.com, pabeni@redhat.com, davem@davemloft.net X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On Wed, 28 Dec 2022 19:43:56 +0800, Jason Wang wrote: > On Wed, Dec 28, 2022 at 4:40 PM Xuan Zhuo wrote: > > > > On Tue, 27 Dec 2022 12:33:53 +0800, Jason Wang wrote: > > > On Tue, Dec 27, 2022 at 10:25 AM Xuan Zhuo wrote: > > > > > > > > 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. > > > > > > Well, it could be tweaked to be a little bit longer. > > > > > > One way, as discussed, is to let the device advertise a timeout then > > > the driver can validate if it's valid and use that timeout. But it > > > needs extension to the spec. > > > > > > > Some of the DPUs are very > > > > lazy for cvq handle. > > > > > > Such design needs to be revisited, cvq (control path) should have a > > > better priority or QOS than datapath. > > > > > > > In particular, we will also directly break the device. > > > > > > It's kind of hardening for malicious devices. > > > > Just based on timeout, it is judged that it is a malicious device. I think it is > > too arbitrary. > > Drivers have very little information to make the decision. So it's > really a balance. > > We can start with a very long timeout like 10 minutes. Otherwise a > buggy/malicious device will block a lot of important things (reboot, > modprobe) even if the scheduler is still functional. Relatively speaking, starting from a 1min+ timeout, I think it is safe. Thanks. > > Thanks > > > > > Thanks. > > > > > > > > > > > > > > > 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. > > > > > > Very hard and unfriendly to the end users. > > > > > > Thanks > > > > > > > > > > > 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 > > > > > > > > > > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization