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(unknown [2a02:6bf:8080:a72::1:38]) by mail-nwsmtp-smtp-corp-main-80.iva.yp-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id ntP1fK1GvGk0-7Md5G5IF; Fri, 19 Sep 2025 12:56:03 +0300 Precedence: bulk X-Yandex-Fwd: 1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1758275763; bh=ZOT4nc4PuASqIOudC/cUMhlxHtQE++eLa6dzdOEVzdA=; h=Message-ID:Date:In-Reply-To:Cc:Subject:References:To:From; b=IiSp9Mik+D3360kmAlIISMNRoLFyJZ6jff+PMaIrg2U7Tc1PhpKv3UHoByuMIL7cO RryXhzDZD1+PIINv1ms+6cmv+9ZiAaH7Hqd4WrrJi7R3zy3tx5T1brAM7XZOfkeioN TKTDkHemBLRIZQunCjxFBlX+c9x8NjHtis0pHNnA= Authentication-Results: mail-nwsmtp-smtp-corp-main-80.iva.yp-c.yandex.net; dkim=pass header.i=@yandex-team.ru From: Vladimir Sementsov-Ogievskiy To: mst@redhat.com Cc: qemu-devel@nongnu.org, philmd@linaro.org, thuth@redhat.com, eblake@redhat.com, michael.roth@amd.com, armbru@redhat.com, farosas@suse.de, peterx@redhat.com, berrange@redhat.com, jasowang@redhat.com, steven.sistare@oracle.com, leiyang@redhat.com, davydov-max@yandex-team.ru, yc-core@yandex-team.ru, Vladimir Sementsov-Ogievskiy Subject: [PATCH v5 17/19] virtio-net: support fds migration of TAP backend Date: Fri, 19 Sep 2025 12:55:43 +0300 Message-ID: <20250919095545.1912042-18-vsementsov@yandex-team.ru> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250919095545.1912042-1-vsementsov@yandex-team.ru> References: <20250919095545.1912042-1-vsementsov@yandex-team.ru> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2a02:6b8:c41:1300:1:45:d181:df01; envelope-from=vsementsov@yandex-team.ru; helo=forwardcorp1d.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, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @yandex-team.ru) X-ZM-MESSAGEID: 1758276034229116600 Content-Type: text/plain; charset="utf-8" Finally implement the new migration option fds =3D [virtio-net]. With this enabled (both on source and target) of-course, and with unix-socket used as migration-channel, we do "migrate" the virtio-net backend - TAP devices, with all its fds. This way management tool should not care about creating new TAP, and handling switching to it. Migration downtime become shorter. How it works: 1. For incoming migration, we postpone TAP initialization up to pre-incoming point. 2. At pre-incoming point we see that virtio-net target for fds migration is set, so we postpone TAP initialization up to post-load 3. During virtio-load, we get TAP state (and fds) as part of virtio-net state 4. In post-load we finalize TAP initialization Signed-off-by: Vladimir Sementsov-Ogievskiy --- hw/net/virtio-net.c | 73 +++++++++++++++++++++++++++++++++++++++++++++ include/net/tap.h | 3 ++ migration/options.c | 5 ---- net/tap.c | 54 ++++++++++++++++++++++++++++++++- 4 files changed, 129 insertions(+), 6 deletions(-) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 70f688fc3a..2817c0f198 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -26,6 +26,7 @@ #include "qemu/option.h" #include "qemu/option_int.h" #include "qemu/config-file.h" +#include "qemu/typedefs.h" #include "qobject/qdict.h" #include "hw/virtio/virtio-net.h" #include "net/vhost_net.h" @@ -38,6 +39,8 @@ #include "qapi/qapi-events-migration.h" #include "hw/virtio/virtio-access.h" #include "migration/misc.h" +#include "migration/migration.h" +#include "migration/options.h" #include "standard-headers/linux/ethtool.h" #include "system/system.h" #include "system/replay.h" @@ -3147,6 +3150,11 @@ static int virtio_net_update_host_features(VirtIONet= *n) Error *local_err =3D NULL; VirtIODevice *vdev =3D VIRTIO_DEVICE(n); =20 + if (peer_wait_incoming(n)) { + /* It's too early for updating options. */ + return 0; + } + peer_test_vnet_hdr(n); =20 vdev->host_features =3D virtio_net_get_features(vdev, vdev->host_featu= res, @@ -3287,6 +3295,9 @@ struct VirtIONetMigTmp { uint16_t curr_queue_pairs_1; uint8_t has_ufo; uint32_t has_vnet_hdr; + + NetClientState *ncs; + uint32_t max_queue_pairs; }; =20 /* The 2nd and subsequent tx_waiting flags are loaded later than @@ -3556,6 +3567,65 @@ static const VMStateDescription vhost_user_net_backe= nd_state =3D { } }; =20 +static bool virtio_net_is_tap_fds_mig(void *opaque, int version_id) +{ + VirtIONet *n =3D opaque; + NetClientState *nc; + + nc =3D qemu_get_queue(n->nic); + + return migrate_fds_virtio_net() && nc->peer && + nc->peer->info->type =3D=3D NET_CLIENT_DRIVER_TAP; +} + +static int virtio_net_nic_pre_save(void *opaque) +{ + struct VirtIONetMigTmp *tmp =3D opaque; + + tmp->ncs =3D tmp->parent->nic->ncs; + tmp->max_queue_pairs =3D tmp->parent->max_queue_pairs; + + return 0; +} + +static int virtio_net_nic_pre_load(void *opaque) +{ + /* Reuse the pointer setup from save */ + virtio_net_nic_pre_save(opaque); + + return 0; +} + +static int virtio_net_nic_post_load(void *opaque, int version_id) +{ + struct VirtIONetMigTmp *tmp =3D opaque; + + return virtio_net_update_host_features(tmp->parent); +} + +static const VMStateDescription vmstate_virtio_net_nic_nc =3D { + .name =3D "virtio-net-nic-nc", + .fields =3D (const VMStateField[]) { + VMSTATE_STRUCT_POINTER(peer, NetClientState, vmstate_tap, + NetClientState), + VMSTATE_END_OF_LIST() + }, +}; + +static const VMStateDescription vmstate_virtio_net_nic =3D { + .name =3D "virtio-net-nic", + .pre_load =3D virtio_net_nic_pre_load, + .pre_save =3D virtio_net_nic_pre_save, + .post_load =3D virtio_net_nic_post_load, + .fields =3D (const VMStateField[]) { + VMSTATE_STRUCT_VARRAY_POINTER_UINT32(ncs, struct VirtIONetMigTmp, + max_queue_pairs, + vmstate_virtio_net_nic_nc, + struct NetClientState), + VMSTATE_END_OF_LIST() + }, +}; + static const VMStateDescription vmstate_virtio_net_device =3D { .name =3D "virtio-net-device", .version_id =3D VIRTIO_NET_VM_VERSION, @@ -3588,6 +3658,9 @@ static const VMStateDescription vmstate_virtio_net_de= vice =3D { * but based on the uint. */ VMSTATE_BUFFER_POINTER_UNSAFE(vlans, VirtIONet, 0, MAX_VLAN >> 3), + VMSTATE_WITH_TMP_TEST(VirtIONet, virtio_net_is_tap_fds_mig, + struct VirtIONetMigTmp, + vmstate_virtio_net_nic), VMSTATE_WITH_TMP(VirtIONet, struct VirtIONetMigTmp, vmstate_virtio_net_has_vnet), VMSTATE_UINT8(mac_table.multi_overflow, VirtIONet), diff --git a/include/net/tap.h b/include/net/tap.h index c6f9c1aeb1..0be083f8da 100644 --- a/include/net/tap.h +++ b/include/net/tap.h @@ -26,6 +26,7 @@ #ifndef QEMU_NET_TAP_H #define QEMU_NET_TAP_H =20 +#include "qemu/typedefs.h" #include "standard-headers/linux/virtio_net.h" =20 int tap_enable(NetClientState *nc); @@ -35,4 +36,6 @@ int tap_get_fd(NetClientState *nc); =20 bool tap_wait_incoming(NetClientState *nc); =20 +extern const VMStateDescription vmstate_tap; + #endif /* QEMU_NET_TAP_H */ diff --git a/migration/options.c b/migration/options.c index 061a1b8eaf..c6eeadaab5 100644 --- a/migration/options.c +++ b/migration/options.c @@ -1192,11 +1192,6 @@ bool migrate_params_check(MigrationParameters *param= s, Error **errp) return false; } =20 - if (params->has_fds) { - error_setg(errp, "Not implemented"); - return false; - } - return true; } =20 diff --git a/net/tap.c b/net/tap.c index 13efea7e4f..dcbc6466e5 100644 --- a/net/tap.c +++ b/net/tap.c @@ -36,6 +36,7 @@ #include "net/net.h" #include "clients.h" #include "migration/misc.h" +#include "migration/options.h" #include "monitor/monitor.h" #include "system/runstate.h" #include "system/system.h" @@ -94,6 +95,7 @@ typedef struct TAPState { int vnet_hdr; bool mq_required; char *ifname; + bool attached_to_virtio_net; } TAPState; =20 static QTAILQ_HEAD(, TAPState) postponed_taps =3D @@ -390,6 +392,8 @@ static bool tap_check_peer_type(NetClientState *nc, Obj= ectClass *oc, } } =20 + s->attached_to_virtio_net =3D true; + return true; } =20 @@ -801,7 +805,7 @@ static void net_init_tap_one(const NetdevTapOptions *ta= p, NetClientState *peer, =20 static bool net_tap_setup(TAPState *s, int fd, int vnet_hdr, Error **errp) { - if (!net_tap_set_fd(s, fd, vnet_hdr, errp)) { + if (fd > -1 && !net_tap_set_fd(s, fd, vnet_hdr, errp)) { return false; } =20 @@ -893,6 +897,7 @@ static int tap_pre_incoming(NotifierWithReturn *notifie= r, { TAPState *s; bool ok =3D true; + bool mig_fds =3D migrate_fds_virtio_net(); =20 if (e->type !=3D MIG_EVENT_PRE_INCOMING) { return 0; @@ -901,6 +906,11 @@ static int tap_pre_incoming(NotifierWithReturn *notifi= er, while (!QTAILQ_EMPTY(&postponed_taps)) { s =3D QTAILQ_FIRST(&postponed_taps); if (ok) { + if (mig_fds && s->attached_to_virtio_net) { + /* We'll get fds from incoming migration */ + QTAILQ_REMOVE(&postponed_taps, s, next); + continue; + } ok =3D tap_postponed_init(s, errp); } else { QTAILQ_REMOVE(&postponed_taps, s, next); @@ -1253,6 +1263,48 @@ int tap_disable(NetClientState *nc) } } =20 +static int tap_pre_load(void *opaque) +{ + TAPState *s =3D opaque; + + if (s->fd !=3D -1) { + error_report( + "TAP is already initialized and cannot receive incoming fd"); + return -EINVAL; + } + + return 0; +} + +static int tap_post_load(void *opaque, int version_id) +{ + TAPState *s =3D opaque; + Error *local_err =3D NULL; + + if (!net_tap_setup(s, -1, -1, &local_err)) { + error_report_err(local_err); + qemu_del_net_client(&s->nc); + return -EINVAL; + } + + return 0; +} + +const VMStateDescription vmstate_tap =3D { + .name =3D "net-tap", + .pre_load =3D tap_pre_load, + .post_load =3D tap_post_load, + .fields =3D (const VMStateField[]) { + VMSTATE_FD(fd, TAPState), + VMSTATE_BOOL(using_vnet_hdr, TAPState), + VMSTATE_BOOL(has_ufo, TAPState), + VMSTATE_BOOL(has_uso, TAPState), + VMSTATE_BOOL(enabled, TAPState), + VMSTATE_UINT32(host_vnet_hdr_len, TAPState), + VMSTATE_END_OF_LIST() + } +}; + bool tap_wait_incoming(NetClientState *nc) { TAPState *s =3D DO_UPCAST(TAPState, nc, nc); --=20 2.48.1