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 B7811C61D97 for ; Sun, 29 Jan 2023 12:10:56 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pM6W3-0001P9-W4; Sun, 29 Jan 2023 07:10:36 -0500 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 1pM6W1-0001Os-0v for qemu-devel@nongnu.org; Sun, 29 Jan 2023 07:10:33 -0500 Received: from out30-99.freemail.mail.aliyun.com ([115.124.30.99]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pM6Vw-00060K-Mz for qemu-devel@nongnu.org; Sun, 29 Jan 2023 07:10:32 -0500 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R201e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=ay29a033018045192; MF=xuanzhuo@linux.alibaba.com; NM=1; PH=DS; RN=4; SR=0; TI=SMTPD_---0VaKVXo8_1674994216; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0VaKVXo8_1674994216) by smtp.aliyun-inc.com; Sun, 29 Jan 2023 20:10:17 +0800 Message-ID: <1674993822.7782302-1-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH v1 2/2] virtio-net: virtio_net_flush_tx() check for per-queue reset Date: Sun, 29 Jan 2023 20:03:42 +0800 From: Xuan Zhuo To: "Michael S. Tsirkin" Cc: qemu-devel@nongnu.org, Jason Wang , Alexander Bulekov References: <20230129025150.119972-1-xuanzhuo@linux.alibaba.com> <20230129025150.119972-3-xuanzhuo@linux.alibaba.com> <20230129021402-mutt-send-email-mst@kernel.org> <1674977308.9335406-2-xuanzhuo@linux.alibaba.com> <20230129025950-mutt-send-email-mst@kernel.org> <1674980588.489446-5-xuanzhuo@linux.alibaba.com> <20230129065705-mutt-send-email-mst@kernel.org> In-Reply-To: <20230129065705-mutt-send-email-mst@kernel.org> Received-SPF: pass client-ip=115.124.30.99; envelope-from=xuanzhuo@linux.alibaba.com; helo=out30-99.freemail.mail.aliyun.com X-Spam_score_int: -98 X-Spam_score: -9.9 X-Spam_bar: --------- X-Spam_report: (-9.9 / 5.0 requ) BAYES_00=-1.9, ENV_AND_HDR_SPF_MATCH=-0.5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, UNPARSEABLE_RELAY=0.001, USER_IN_DEF_SPF_WL=-7.5 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 On Sun, 29 Jan 2023 06:57:29 -0500, "Michael S. Tsirkin" wrote: > On Sun, Jan 29, 2023 at 04:23:08PM +0800, Xuan Zhuo wrote: > > On Sun, 29 Jan 2023 03:12:12 -0500, "Michael S. Tsirkin" wrote: > > > On Sun, Jan 29, 2023 at 03:28:28PM +0800, Xuan Zhuo wrote: > > > > On Sun, 29 Jan 2023 02:25:43 -0500, "Michael S. Tsirkin" wrote: > > > > > On Sun, Jan 29, 2023 at 10:51:50AM +0800, Xuan Zhuo wrote: > > > > > > Check whether it is per-queue reset state in virtio_net_flush_tx(). > > > > > > > > > > > > Before per-queue reset, we need to recover async tx resources. At this > > > > > > time, virtio_net_flush_tx() is called, but we should not try to send > > > > > > new packets, so virtio_net_flush_tx() should check the current > > > > > > per-queue reset state. > > > > > > > > > > > > > > > What does "at this time" mean here? > > > > > Do you in fact mean it's called from flush_or_purge_queued_packets? > > > > > > > > Yes > > > > > > > > virtio_queue_reset > > > > k->queue_reset > > > > virtio_net_queue_reset > > > > flush_or_purge_queued_packets > > > > qemu_flush_or_purge_queued_packets > > > > ..... > > > > (callback) virtio_net_tx_complete > > > > virtio_net_flush_tx <-- here send new packet. We need stop it. > > > > > > > > > > > > Because it is inside the callback, I can't pass information through the stack. I > > > > originally thought it was a general situation, so I wanted to put it in > > > > struct VirtQueue. > > > > > > > > If it is not very suitable, it may be better to put it in VirtIONetQueue. > > > > > > > > Thanks. > > > > > > Hmm maybe. Another idea: isn't virtio_net_tx_complete called > > > with length 0 here? Are there other cases where length is 0? > > > > > > > > > > > What does the call stack look like? > > > > > > > > > > If yes introducing a vq state just so virtio_net_flush_tx > > > > > knows we are in the process of reset would be a bad idea. > > > > > We want something much more local, ideally on stack even ... > > > > > > > > > > > > > > > > > > > > > > Fixes: 7dc6be52 ("virtio-net: support queue reset") > > > > > > Fixes: https://gitlab.com/qemu-project/qemu/-/issues/1451 > > > > > > Reported-by: Alexander Bulekov > > > > > > Signed-off-by: Xuan Zhuo > > > > > > --- > > > > > > hw/net/virtio-net.c | 3 ++- > > > > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > > > > > > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > > > > > > index 3ae909041a..fba6451a50 100644 > > > > > > --- a/hw/net/virtio-net.c > > > > > > +++ b/hw/net/virtio-net.c > > > > > > @@ -2627,7 +2627,8 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q) > > > > > > VirtQueueElement *elem; > > > > > > int32_t num_packets = 0; > > > > > > int queue_index = vq2q(virtio_get_queue_index(q->tx_vq)); > > > > > > - if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) { > > > > > > + if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) || > > > > > > + virtio_queue_reset_state(q->tx_vq)) { > > > > > > btw this sounds like you are asking it to reset some state. > > > > > > > > > return num_packets; > > > > > > and then > > > > > > ret = virtio_net_flush_tx(q); > > > if (ret >= n->tx_burst) > > > > > > > > > will reschedule automatically won't it? > > > > > > also why check in virtio_net_flush_tx and not virtio_net_tx_complete? > > > > virtio_net_flush_tx may been called by timer. > > > > Thanks. > > timer won't run while flush_or_purge_queued_packets is in progress. Is timer not executed during the VMEXIT process? Otherwise, we still have to consider that after the flush_or_purge_queued_packets, this process before the structure is cleared. Even if it can be processed in virtio_net_tx_complete, is there any good way? This is a callback, it is not convenient to pass the parameters. Thanks > > > > > > > > > > > > > } > > > > > > > > > > > > -- > > > > > > 2.32.0.3.g01195cf9f > > > > > > > > >