From patchwork Fri Feb 3 19:11:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Eugenio Perez Martin X-Patchwork-Id: 13128285 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 DDC3CC636CC for ; Fri, 3 Feb 2023 19:12:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pO1TZ-0006Vy-LE; Fri, 03 Feb 2023 14:11:57 -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 1pO1TX-0006Ur-L0 for qemu-devel@nongnu.org; Fri, 03 Feb 2023 14:11:55 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pO1TV-0007Xq-E4 for qemu-devel@nongnu.org; Fri, 03 Feb 2023 14:11:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675451511; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=gX4e9kHjMFhdnFMUhR5qLBHohE/y+CLzUaexiSkoZPw=; b=Izov3EPAG1hH5OooGK3NVhLry99S6pyq5eXOWvGOstpx0pduqrTH+ZnVIz0GfpU3wlhRZW +pBa852R6qPj3CFxsbwFzGhUuUUM1jClGLU+i3/70ZwM3+64T52HTAR3QYEuBftYI9Ws80 f5oHyRQ73h9Xq2yMwp0uyLr9xDV//AI= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-57-5G8vqQd_Pqqv0SpuHiEyLw-1; Fri, 03 Feb 2023 14:11:48 -0500 X-MC-Unique: 5G8vqQd_Pqqv0SpuHiEyLw-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 70487380606C; Fri, 3 Feb 2023 19:11:47 +0000 (UTC) Received: from eperezma.remote.csb (unknown [10.39.194.221]) by smtp.corp.redhat.com (Postfix) with ESMTP id 42A3D492C14; Fri, 3 Feb 2023 19:11:44 +0000 (UTC) From: =?utf-8?q?Eugenio_P=C3=A9rez?= To: qemu-devel@nongnu.org Cc: Cindy Lu , Liuxiangdong , alvaro.karsz@solid-run.com, Zhu Lingshan , Jason Wang , longpeng2@huawei.com, "Michael S. Tsirkin" , Shannon Nelson , Eli Cohen , Stefan Hajnoczi , virtualization@lists.linux-foundation.org, Parav Pandit , si-wei.liu@oracle.com, Laurent Vivier , Gautam Dawar , Stefano Garzarella , Harpreet Singh Anand , "Gonglei (Arei)" Subject: [PATCH 00/13] Dynamycally switch to vhost shadow virtqueues at vdpa net migration Date: Fri, 3 Feb 2023 20:11:29 +0100 Message-Id: <20230203191142.362623-1-eperezma@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.129.124; envelope-from=eperezma@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org It's possible to migrate vdpa net devices if they are shadowed from the start. But to always shadow the dataplane is to effectively break its host passthrough, so its not convenient in vDPA scenarios. This series enables dynamically switching to shadow mode only at migration time. This allows full data virtqueues passthrough all the time qemu is not migrating. In this series only net devices with no CVQ are migratable. CVQ adds additional state that would make the series bigger and still had some controversy on previous RFC, so let's split it. The first patch delays the creation of the iova tree until it is really needed, and makes it easier to dynamically move from and to SVQ mode. Next patches from 02 to 05 handle the suspending and getting of vq state (base) of the device at the switch to SVQ mode. The new _F_SUSPEND feature is negotiated and stop device flow is changed so the state can be fetched trusting the device will not modify it. Since vhost backend must offer VHOST_F_LOG_ALL to be migratable, last patches but the last one add the needed migration blockers so vhost-vdpa can offer it safely. They also add the handling of this feature. Finally, the last patch makes virtio vhost-vdpa backend to offer VHOST_F_LOG_ALL so qemu migrate the device as long as no other blocker has been added. Successfully tested with vdpa_sim_net with patch [1] applied and with the qemu emulated device with vp_vdpa with some restrictions: * No CVQ. No feature that didn't work with SVQ previously (packed, ...) * VIRTIO_RING_F_STATE patches implementing [2]. * Expose _F_SUSPEND, but ignore it and suspend on ring state fetch like DPDK. Comments are welcome. v1: - Omit all code working with CVQ and block migration if the device supports CVQ. - Remove spurious kick. - Move all possible checks for migration to vhost-vdpa instead of the net backend. Move them to init code from start code. - Suspend on vhost_vdpa_dev_start(false) instead of in vhost-vdpa net backend. - Properly split suspend after geting base and adding of status_reset patches. - Add possible TODOs to points where this series can improve in the future. - Check the state of migration using migration_in_setup and migration_has_failed instead of checking all the possible migration status in a switch. - Add TODO with possible low hand fruit using RESUME ops. - Always offer _F_LOG from virtio/vhost-vdpa and let migration blockers do their thing instead of adding a variable. - RFC v2 at https://lists.gnu.org/archive/html/qemu-devel/2023-01/msg02574.html RFC v2: - Use a migration listener instead of a memory listener to know when the migration starts. - Add stuff not picked with ASID patches, like enable rings after driver_ok - Add rewinding on the migration src, not in dst - RFC v1 at https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg01664.html [1] https://lore.kernel.org/lkml/20230203142501.300125-1-eperezma@redhat.com/T/ [2] https://lists.oasis-open.org/archives/virtio-comment/202103/msg00036.html Eugenio Pérez (13): vdpa net: move iova tree creation from init to start vdpa: Negotiate _F_SUSPEND feature vdpa: add vhost_vdpa_suspend vdpa: move vhost reset after get vring base vdpa: rewind at get_base, not set_base vdpa net: allow VHOST_F_LOG_ALL vdpa: add vdpa net migration state notifier vdpa: disable RAM block discard only for the first device vdpa net: block migration if the device has CVQ vdpa: block migration if device has unsupported features vdpa: block migration if dev does not have _F_SUSPEND vdpa: block migration if SVQ does not admit a feature vdpa: return VHOST_F_LOG_ALL in vhost-vdpa devices include/hw/virtio/vhost-backend.h | 4 + hw/virtio/vhost-vdpa.c | 126 +++++++++++++++----- hw/virtio/vhost.c | 3 + net/vhost-vdpa.c | 192 +++++++++++++++++++++++++----- hw/virtio/trace-events | 1 + 5 files changed, 267 insertions(+), 59 deletions(-)