{"id":2198119,"url":"http://patchwork.ozlabs.org/api/1.0/patches/2198119/?format=json","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/1.0/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260219115530.2019498-7-vsementsov@yandex-team.ru>","date":"2026-02-19T11:55:27","name":"[v11,6/8] net/tap: support local migration with virtio-net","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"066e139b5787d5a9b0a799cfeac6541eaca0210b","submitter":{"id":84116,"url":"http://patchwork.ozlabs.org/api/1.0/people/84116/?format=json","name":"Vladimir Sementsov-Ogievskiy","email":"vsementsov@yandex-team.ru"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260219115530.2019498-7-vsementsov@yandex-team.ru/mbox/","series":[{"id":492667,"url":"http://patchwork.ozlabs.org/api/1.0/series/492667/?format=json","date":"2026-02-19T11:55:27","name":"virtio-net: live-TAP local migration","version":11,"mbox":"http://patchwork.ozlabs.org/series/492667/mbox/"}],"check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2198119/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=yandex-team.ru header.i=@yandex-team.ru\n header.a=rsa-sha256 header.s=default header.b=vSiaFSFq;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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Thu, 19 Feb 2026 06:55:44 -0500","from mail-nwsmtp-smtp-corp-main-34.sas.yp-c.yandex.net\n (mail-nwsmtp-smtp-corp-main-34.sas.yp-c.yandex.net\n [IPv6:2a02:6b8:c24:fa2:0:640:41ee:0])\n by forwardcorp1b.mail.yandex.net (Yandex) with ESMTPS id DDEA6808BA;\n Thu, 19 Feb 2026 14:55:40 +0300 (MSK)","from vsementsov-lin (unknown [2a02:6bf:8080:192::1:26])\n by mail-nwsmtp-smtp-corp-main-34.sas.yp-c.yandex.net (smtpcorp/Yandex) with\n ESMTPSA id VtZwpM4A6uQ0-wujyPL65; Thu, 19 Feb 2026 14:55:40 +0300"],"Precedence":"bulk","X-Yandex-Fwd":"1","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru;\n s=default; t=1771502140;\n bh=YKdHNL8F4xc0z/xXa7YTpcea+oVF1roRqyiwl/iJsKw=;\n h=Message-ID:Date:In-Reply-To:Cc:Subject:References:To:From;\n b=vSiaFSFqc93WijllvYcHbedmH0L6E4GvQbiJWTlohsaLiHpQaEvlA4D+eOW3UUTlT\n /9jv6Ry7CFcyTXdIDtOUwvHY7QwQQKwGppHj611Tj/SPgL1CFDv9LbE3bBgAkaZ5cq\n o7leUTlobuvRGSRUyXNCUcQ6hEskC7bwy+KJwPkQ=","From":"Vladimir Sementsov-Ogievskiy ","To":"jasowang@redhat.com,\n\tmst@redhat.com","Cc":"thuth@redhat.com, armbru@redhat.com, eblake@redhat.com, farosas@suse.de,\n peterx@redhat.com, zhao1.liu@intel.com, wangyanan55@huawei.com,\n philmd@linaro.org, marcel.apfelbaum@gmail.com, eduardo@habkost.net,\n davydov-max@yandex-team.ru, qemu-devel@nongnu.org,\n vsementsov@yandex-team.ru, yc-core@yandex-team.ru, leiyang@redhat.com,\n raphael.s.norwitz@gmail.com, bchaney@akamai.com","Subject":"[PATCH v11 6/8] net/tap: support local migration with virtio-net","Date":"Thu, 19 Feb 2026 14:55:27 +0300","Message-ID":"<20260219115530.2019498-7-vsementsov@yandex-team.ru>","X-Mailer":"git-send-email 2.52.0","In-Reply-To":"<20260219115530.2019498-1-vsementsov@yandex-team.ru>","References":"<20260219115530.2019498-1-vsementsov@yandex-team.ru>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","Received-SPF":"pass client-ip=178.154.239.136;\n envelope-from=vsementsov@yandex-team.ru; helo=forwardcorp1b.mail.yandex.net","X-Spam_score_int":"-20","X-Spam_score":"-2.1","X-Spam_bar":"--","X-Spam_report":"(-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001,\n RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001,\n SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","List-Id":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"Support transferring of TAP state (including open fd) through\nmigration stream as part of viritio-net \"local-migration\".\n\nAdd new option, incoming-fds, which should be set to true to\ntrigger new logic.\n\nSigned-off-by: Vladimir Sementsov-Ogievskiy \n---\n net/tap.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++-\n qapi/net.json | 6 +++-\n 2 files changed, 96 insertions(+), 2 deletions(-)","diff":"diff --git a/net/tap.c b/net/tap.c\nindex 294ca61f8b..f6e4a36e97 100644\n--- a/net/tap.c\n+++ b/net/tap.c\n@@ -393,6 +393,65 @@ static VHostNetState *tap_get_vhost_net(NetClientState *nc)\n return s->vhost_net;\n }\n \n+static bool tap_is_wait_incoming(NetClientState *nc)\n+{\n+ TAPState *s = DO_UPCAST(TAPState, nc, nc);\n+ assert(nc->info->type == NET_CLIENT_DRIVER_TAP);\n+ return s->fd == -1;\n+}\n+\n+static int tap_pre_load(void *opaque)\n+{\n+ TAPState *s = opaque;\n+\n+ if (s->fd != -1) {\n+ error_report(\n+ \"TAP is already initialized and cannot receive incoming fd\");\n+ return -EINVAL;\n+ }\n+\n+ return 0;\n+}\n+\n+static bool tap_setup_vhost(TAPState *s, Error **errp);\n+\n+static int tap_post_load(void *opaque, int version_id)\n+{\n+ TAPState *s = opaque;\n+ Error *local_err = NULL;\n+\n+ tap_read_poll(s, true);\n+\n+ if (s->fd < 0) {\n+ return -1;\n+ }\n+\n+ if (!tap_setup_vhost(s, &local_err)) {\n+ error_prepend(&local_err,\n+ \"Failed to setup vhost during TAP post-load: \");\n+ error_report_err(local_err);\n+ return -1;\n+ }\n+\n+ return 0;\n+}\n+\n+static const VMStateDescription vmstate_tap = {\n+ .name = \"net-tap\",\n+ .pre_load = tap_pre_load,\n+ .post_load = tap_post_load,\n+ .fields = (const VMStateField[]) {\n+ VMSTATE_FD(fd, TAPState),\n+ VMSTATE_BOOL(using_vnet_hdr, TAPState),\n+ VMSTATE_BOOL(has_ufo, TAPState),\n+ VMSTATE_BOOL(has_uso, TAPState),\n+ VMSTATE_BOOL(has_tunnel, TAPState),\n+ VMSTATE_BOOL(enabled, TAPState),\n+ VMSTATE_UINT32(host_vnet_hdr_len, TAPState),\n+ VMSTATE_END_OF_LIST()\n+ }\n+};\n+\n /* fd support */\n \n static NetClientInfo net_tap_info = {\n@@ -412,7 +471,9 @@ static NetClientInfo net_tap_info = {\n .set_vnet_le = tap_set_vnet_le,\n .set_vnet_be = tap_set_vnet_be,\n .set_steering_ebpf = tap_set_steering_ebpf,\n+ .is_wait_incoming = tap_is_wait_incoming,\n .get_vhost_net = tap_get_vhost_net,\n+ .backend_vmsd = &vmstate_tap,\n };\n \n static TAPState *net_tap_fd_init(NetClientState *peer,\n@@ -905,6 +966,12 @@ int net_init_tap(const Netdev *netdev, const char *name,\n return -1;\n }\n \n+ if (tap->incoming_fds && (tap->fd || tap->fds || tap->helper)) {\n+ error_setg(errp, \"incoming-fds is incompatible with \"\n+ \"fd=, fds=, helper=\");\n+ return -1;\n+ }\n+\n queues = tap_parse_fds_and_queues(tap, &fds, errp);\n if (queues < 0) {\n return -1;\n@@ -923,7 +990,24 @@ int net_init_tap(const Netdev *netdev, const char *name,\n goto fail;\n }\n \n- if (fds) {\n+ if (tap->incoming_fds) {\n+ for (i = 0; i < queues; i++) {\n+ NetClientState *nc;\n+ TAPState *s;\n+\n+ nc = qemu_new_net_client(&net_tap_info, peer, \"tap\", name);\n+ qemu_set_info_str(nc, \"incoming\");\n+\n+ s = DO_UPCAST(TAPState, nc, nc);\n+ s->fd = -1;\n+ if (vhost_fds) {\n+ s->vhostfd = vhost_fds[i];\n+ s->vhost_busyloop_timeout = tap->has_poll_us ? tap->poll_us : 0;\n+ } else {\n+ s->vhostfd = -1;\n+ }\n+ }\n+ } else if (fds) {\n for (i = 0; i < queues; i++) {\n if (i == 0) {\n vnet_hdr = tap_probe_vnet_hdr(fds[i], errp);\n@@ -949,6 +1033,12 @@ int net_init_tap(const Netdev *netdev, const char *name,\n g_autofree char *downscript =\n tap_parse_script(tap->downscript, DEFAULT_NETWORK_DOWN_SCRIPT);\n \n+ if (tap->incoming_fds && (script || downscript)) {\n+ error_setg(errp,\n+ \"incoming-fds requires script=no and downscript=no\");\n+ return -1;\n+ }\n+\n if (tap->ifname) {\n pstrcpy(ifname, sizeof ifname, tap->ifname);\n } else {\ndiff --git a/qapi/net.json b/qapi/net.json\nindex 118bd34965..79f5ce9f43 100644\n--- a/qapi/net.json\n+++ b/qapi/net.json\n@@ -355,6 +355,9 @@\n # @poll-us: maximum number of microseconds that could be spent on busy\n # polling for tap (since 2.7)\n #\n+# @incoming-fds: do not open/connnect any resources, instead wait for\n+# TAP state from incoming migration stream. (Since 11.0)\n+#\n # Since: 1.2\n ##\n { 'struct': 'NetdevTapOptions',\n@@ -373,7 +376,8 @@\n '*vhostfds': 'str',\n '*vhostforce': 'bool',\n '*queues': 'uint32',\n- '*poll-us': 'uint32'} }\n+ '*poll-us': 'uint32',\n+ '*incoming-fds': 'bool' } }\n \n ##\n # @NetdevSocketOptions:\n","prefixes":["v11","6/8"]}