From nobody Fri Dec 19 06:29:40 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1522047758505690.6578888534264; Mon, 26 Mar 2018 00:02:38 -0700 (PDT) Received: from localhost ([::1]:54932 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f0M9N-0003Do-Pa for importer@patchew.org; Mon, 26 Mar 2018 03:02:37 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42832) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f0M7h-0002JF-9U for qemu-devel@nongnu.org; Mon, 26 Mar 2018 03:00:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f0M7b-0000tH-35 for qemu-devel@nongnu.org; Mon, 26 Mar 2018 03:00:53 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:39288 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1f0M7a-0000t9-Th; Mon, 26 Mar 2018 03:00:47 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 560F0722C0; Mon, 26 Mar 2018 07:00:46 +0000 (UTC) Received: from jason-ThinkPad-T450s.redhat.com (ovpn-12-191.pek2.redhat.com [10.72.12.191]) by smtp.corp.redhat.com (Postfix) with ESMTP id 74178215CDAA; Mon, 26 Mar 2018 07:00:40 +0000 (UTC) From: Jason Wang To: qemu-devel@nongnu.org, peter.maydell@linaro.org Date: Mon, 26 Mar 2018 15:00:28 +0800 Message-Id: <1522047629-27658-2-git-send-email-jasowang@redhat.com> In-Reply-To: <1522047629-27658-1-git-send-email-jasowang@redhat.com> References: <1522047629-27658-1-git-send-email-jasowang@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Mon, 26 Mar 2018 07:00:46 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Mon, 26 Mar 2018 07:00:46 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'jasowang@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PULL 1/2] virtio_net: flush uncompleted TX on reset X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jason Wang , Greg Kurz , qemu-stable@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Greg Kurz If the backend could not transmit a packet right away for some reason, the packet is queued for asynchronous sending. The corresponding vq element is tracked in the async_tx.elem field of the VirtIONetQueue, for later freeing when the transmission is complete. If a reset happens before completion, virtio_net_tx_complete() will push async_tx.elem back to the guest anyway, and we end up with the inuse flag of the vq being equal to -1. The next call to virtqueue_pop() is then likely to fail with "Virtqueue size exceeded". This can be reproduced easily by starting a guest with an hubport backend that is not connected to a functional network, eg, -device virtio-net-pci,netdev=3Dhub0 -netdev hubport,id=3Dhub0,hubid=3D0 and no other -netdev hubport,hubid=3D0 on the command line. The appropriate fix is to ensure that such an asynchronous transmission cannot survive a device reset. So for all queues, we first try to send the packet again, and eventually we purge it if the backend still could not deliver it. CC: qemu-stable@nongnu.org Reported-by: R. Nageswara Sastry Buglink: https://github.com/open-power-host-os/qemu/issues/37 Signed-off-by: Greg Kurz Tested-by: R. Nageswara Sastry Signed-off-by: Jason Wang --- hw/net/virtio-net.c | 11 +++++++++++ include/net/net.h | 1 + net/net.c | 1 - 3 files changed, 12 insertions(+), 1 deletion(-) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 67ad38c..90502fc 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -427,6 +427,7 @@ static RxFilterInfo *virtio_net_query_rxfilter(NetClien= tState *nc) static void virtio_net_reset(VirtIODevice *vdev) { VirtIONet *n =3D VIRTIO_NET(vdev); + int i; =20 /* Reset back to compatibility mode */ n->promisc =3D 1; @@ -450,6 +451,16 @@ static void virtio_net_reset(VirtIODevice *vdev) memcpy(&n->mac[0], &n->nic->conf->macaddr, sizeof(n->mac)); qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac); memset(n->vlans, 0, MAX_VLAN >> 3); + + /* Flush any async TX */ + for (i =3D 0; i < n->max_queues; i++) { + NetClientState *nc =3D qemu_get_subqueue(n->nic, i); + + if (nc->peer) { + qemu_flush_or_purge_queued_packets(nc->peer, true); + assert(!virtio_net_get_subqueue(nc)->async_tx.elem); + } + } } =20 static void peer_test_vnet_hdr(VirtIONet *n) diff --git a/include/net/net.h b/include/net/net.h index a943e96..1f7341e 100644 --- a/include/net/net.h +++ b/include/net/net.h @@ -153,6 +153,7 @@ ssize_t qemu_send_packet_async(NetClientState *nc, cons= t uint8_t *buf, int size, NetPacketSent *sent_cb); void qemu_purge_queued_packets(NetClientState *nc); void qemu_flush_queued_packets(NetClientState *nc); +void qemu_flush_or_purge_queued_packets(NetClientState *nc, bool purge); void qemu_format_nic_info_str(NetClientState *nc, uint8_t macaddr[6]); bool qemu_has_ufo(NetClientState *nc); bool qemu_has_vnet_hdr(NetClientState *nc); diff --git a/net/net.c b/net/net.c index 5222e45..29f8398 100644 --- a/net/net.c +++ b/net/net.c @@ -595,7 +595,6 @@ void qemu_purge_queued_packets(NetClientState *nc) qemu_net_queue_purge(nc->peer->incoming_queue, nc); } =20 -static void qemu_flush_or_purge_queued_packets(NetClientState *nc, bool purge) { nc->receive_disabled =3D 0; --=20 2.7.4