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Tsirkin" , Stefano Garzarella , Kevin Wolf , Hanna Reitz , Peter Xu , Fabiano Rosas , Eric Blake , Markus Armbruster , Alexandr Moshkov Subject: [PATCH v3 3/3] vhost-user-blk: support inter-host inflight migration Date: Mon, 10 Nov 2025 15:39:41 +0500 Message-Id: <20251110103937.1944486-4-dtalexundeer@yandex-team.ru> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20251110103937.1944486-1-dtalexundeer@yandex-team.ru> References: <20251110103937.1944486-1-dtalexundeer@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=178.154.239.200; envelope-from=dtalexundeer@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, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, 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 Precedence: list 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: 1762772579206158500 Content-Type: text/plain; charset="utf-8" During inter-host migration, waiting for disk requests to be drained in the vhost-user backend can incur significant downtime. This can be avoided if QEMU migrates the inflight region in vhost-user-blk. Thus, during the qemu migration, the vhost-user backend can cancel all inflight requests and then, after migration, they will be executed on another host. In vhost_user_blk_stop() on incoming inter-host migration make force_stop =3D true, so GET_VRING_BASE will not be executed. Signed-off-by: Alexandr Moshkov --- hw/block/vhost-user-blk.c | 29 +++++++++++++++++++++++++++++ include/hw/virtio/vhost-user-blk.h | 1 + 2 files changed, 30 insertions(+) diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c index a8fd90480a..2d9b398de6 100644 --- a/hw/block/vhost-user-blk.c +++ b/hw/block/vhost-user-blk.c @@ -139,6 +139,14 @@ const VhostDevConfigOps blk_ops =3D { .vhost_dev_config_notifier =3D vhost_user_blk_handle_config_change, }; =20 +static bool vhost_user_blk_inflight_needed(void *opaque) +{ + struct VHostUserBlk *s =3D opaque; + + return s->skip_get_vring_base_inflight_migration && + !migrate_local_vhost_user_blk(); +} + static int vhost_user_blk_start(VirtIODevice *vdev, Error **errp) { VHostUserBlk *s =3D VHOST_USER_BLK(vdev); @@ -242,6 +250,11 @@ static int vhost_user_blk_stop(VirtIODevice *vdev) force_stop =3D s->skip_get_vring_base_on_force_shutdown && qemu_force_shutdown_requested(); =20 + if (vhost_user_blk_inflight_needed(s) && + runstate_check(RUN_STATE_FINISH_MIGRATE)) { + force_stop =3D true; + } + s->dev.backend_transfer =3D s->dev.backend_transfer || (runstate_check(RUN_STATE_FINISH_MIGRATE) && migrate_local_vhost_user_blk()); @@ -656,6 +669,16 @@ static struct vhost_dev *vhost_user_blk_get_vhost(Virt= IODevice *vdev) return &s->dev; } =20 +static const VMStateDescription vmstate_vhost_user_blk_inflight =3D { + .name =3D "vhost-user-blk/inflight", + .version_id =3D 1, + .needed =3D vhost_user_blk_inflight_needed, + .fields =3D (const VMStateField[]) { + VMSTATE_VHOST_INFLIGHT_REGION(inflight, VHostUserBlk), + VMSTATE_END_OF_LIST() + }, +}; + static bool vhost_user_blk_pre_incoming(void *opaque, Error **errp) { VHostUserBlk *s =3D VHOST_USER_BLK(opaque); @@ -678,6 +701,10 @@ static const VMStateDescription vmstate_vhost_user_blk= =3D { VMSTATE_VIRTIO_DEVICE, VMSTATE_END_OF_LIST() }, + .subsections =3D (const VMStateDescription * const []) { + &vmstate_vhost_user_blk_inflight, + NULL + } }; =20 static bool vhost_user_needed(void *opaque) @@ -751,6 +778,8 @@ static const Property vhost_user_blk_properties[] =3D { VIRTIO_BLK_F_WRITE_ZEROES, true), DEFINE_PROP_BOOL("skip-get-vring-base-on-force-shutdown", VHostUserBlk, skip_get_vring_base_on_force_shutdown, false), + DEFINE_PROP_BOOL("skip-get-vring-base-inflight-migration", VHostUserBl= k, + skip_get_vring_base_inflight_migration, false), }; =20 static void vhost_user_blk_class_init(ObjectClass *klass, const void *data) diff --git a/include/hw/virtio/vhost-user-blk.h b/include/hw/virtio/vhost-u= ser-blk.h index b06f55fd6f..859fb96956 100644 --- a/include/hw/virtio/vhost-user-blk.h +++ b/include/hw/virtio/vhost-user-blk.h @@ -52,6 +52,7 @@ struct VHostUserBlk { bool started_vu; =20 bool skip_get_vring_base_on_force_shutdown; + bool skip_get_vring_base_inflight_migration; =20 bool incoming_backend; }; --=20 2.34.1