From mboxrd@z Thu Jan 1 00:00:00 1970 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 83CC1C64ED8 for ; Mon, 27 Feb 2023 12:46:25 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pWcop-0005lZ-5L; Mon, 27 Feb 2023 07:41:28 -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 1pWcoA-0005Ij-A7 for qemu-devel@nongnu.org; Mon, 27 Feb 2023 07:40:55 -0500 Received: from mail-pf1-x434.google.com ([2607:f8b0:4864:20::434]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1pWco5-0001m4-W2 for qemu-devel@nongnu.org; Mon, 27 Feb 2023 07:40:43 -0500 Received: by mail-pf1-x434.google.com with SMTP id ce7so3415649pfb.9 for ; Mon, 27 Feb 2023 04:40:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=solid-run-com.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=S2jhasNjoy802hJ5uR0TgTEFUPCoR2lDLD3l4YCiU10=; b=QW7wHSpafPjwd7TaL6/+tHtP86DxIsIbik99Z/cop3ea1f+RrzBqosm4H3vmFA30lI YmsHN6qenC29DXU/HQ3jnGx8SD7JJbXF/Ky/dqmr/dTWDpLd3ZUsMmXwmxAE6W934pmz 4Qgcuo2iVRLxIGv+g4wcE3qLmpT9gQ4coJTRdnGumpINYXl8mXn+mVrHYE/Y/r53y6wx 5IzYxpNImD1nXBFXcBeIahdFrH3Zm/S0MmqTDTtHfho8cEGKbthiWVOG6XhMYpUY1Zhi Wc78RDevYI5Q7B8869hWX2HaZvvgtlubgAcuQ8i7EPNwxkqcufYKA99vskYotgIAPucW kVrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=S2jhasNjoy802hJ5uR0TgTEFUPCoR2lDLD3l4YCiU10=; b=VRnZmB83T8pz3qzzRuCLIXUWyBr/yp8TZNRSYOzRGhnXrTV3u/we3KJ+C5iwxSlDTS Ts5cvPnX2gjdcM0uRAtz9ofUolLKC8P40rz42l4RwqQ+U921aMDdhT58czm7cXFeu7Dk Z01sWhqlOfRw1woN+vzhdWTNbHCm3EbY0X0cRcg73Tv2JvGFj6K7C40fWN+QVMyaPnR1 voCJC56rm6D+VKLq8lIwG9QXkhuof++bRNXmmucZAbuxkBsWDRetZIzN/5VXZHWyKStf H+x0wqsc2HGY9UiTjjoXuB4yDvkoSDDmpXiCesrrEPeH7RJ/ft73c6Eu9gh1GIeCeGF/ uqfA== X-Gm-Message-State: AO0yUKV0MqWKaBoyshVq+msQlWEq9N1Yx4qJnw9kzj1xezcFsWRTIcy1 c7bX0UjoO7APdmVIrca/uZIGigyz5/lrmAZn4OaQEg== X-Google-Smtp-Source: AK7set/YVkPThBzFKuxa/rdrEXhC1I+scq6HJaE9jiZU7WaOxbb5GKqwj45Rl6til8gIhoy8jWB+6rkrowSffmrJEgg= X-Received: by 2002:a63:364a:0:b0:4ff:6b33:5a3a with SMTP id d71-20020a63364a000000b004ff6b335a3amr5777628pga.2.1677501638125; Mon, 27 Feb 2023 04:40:38 -0800 (PST) MIME-Version: 1.0 References: <20230224155438.112797-1-eperezma@redhat.com> In-Reply-To: <20230224155438.112797-1-eperezma@redhat.com> From: Alvaro Karsz Date: Mon, 27 Feb 2023 14:40:01 +0200 Message-ID: Subject: Re: [PATCH v4 00/15] Dynamically switch to vhost shadow virtqueues at vdpa net migration To: =?UTF-8?Q?Eugenio_P=C3=A9rez?= Cc: qemu-devel@nongnu.org, Stefano Garzarella , Shannon Nelson , Jason Wang , Gautam Dawar , Laurent Vivier , longpeng2@huawei.com, virtualization@lists.linux-foundation.org, Stefan Hajnoczi , Cindy Lu , "Michael S. Tsirkin" , si-wei.liu@oracle.com, Liuxiangdong , Parav Pandit , Eli Cohen , Zhu Lingshan , Harpreet Singh Anand , "Gonglei (Arei)" , Lei Yang Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: permerror client-ip=2607:f8b0:4864:20::434; envelope-from=alvaro.karsz@solid-run.com; helo=mail-pf1-x434.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, T_SPF_PERMERROR=0.01 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 ho= st > passthrough, so its not efficient 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. > > 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. > > Previous versions were tested by many vendors. Not carrying Tested-by bec= ause > of code changes, so re-testing would be appreciated. > > Comments are welcome. > > v4: > - Recover used_idx from guest's vring if device cannot suspend. > - Fix starting device in the middle of a migration. Removed some > duplication in setting / clearing enable_shadow_vqs and shadow_data > members of vhost_vdpa. > - Fix (again) "Check for SUSPEND in vhost_dev.backend_cap, as > .backend_features is empty at the check moment.". It was reverted by > mistake in v3. > - Fix memory leak of iova tree. > - Properly rewind SVQ as in flight descriptors were still being accounted > in vq base. > - Expand documentation. > > v3: > - Start datapatch in SVQ in device started while migrating. > - Properly register migration blockers if device present unsupported feat= ures. > - Fix race condition because of not stopping the SVQ until device cleanup= . > - Explain purpose of iova tree in the first patch message. > - s/dynamycally/dynamically/ in cover letter. > - at lore.kernel.org/qemu-devel/20230215173850.298832-14-eperezma@redhat.= com > > v2: > - Check for SUSPEND in vhost_dev.backend_cap, as .backend_features is emp= ty at > the check moment. > - at https://lore.kernel.org/all/20230208094253.702672-12-eperezma@redhat= .com/T/ > > v1: > - Omit all code working with CVQ and block migration if the device suppor= ts > 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 bac= kend. > - Properly split suspend after geting base and adding of status_reset pat= ches. > - Add possible TODOs to points where this series can improve in the futur= e. > - Check the state of migration using migration_in_setup and > migration_has_failed instead of checking all the possible migration sta= tus 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 d= o > their thing instead of adding a variable. > - RFC v2 at https://lists.gnu.org/archive/html/qemu-devel/2023-01/msg0257= 4.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/msg0166= 4.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 P=C3=A9rez (15): > vdpa net: move iova tree creation from init to start > vdpa: Remember last call fd set > vdpa: stop svq at vhost_vdpa_dev_start(false) > vdpa: Negotiate _F_SUSPEND feature > vdpa: move vhost reset after get vring base > vdpa: add vhost_vdpa->suspended parameter > vdpa: add vhost_vdpa_suspend > vdpa: rewind at get_base, not set_base > 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 SVQ does not admit a feature > vdpa net: allow VHOST_F_LOG_ALL > vdpa: return VHOST_F_LOG_ALL in vhost-vdpa devices > > include/hw/virtio/vhost-backend.h | 4 + > include/hw/virtio/vhost-vdpa.h | 3 + > hw/virtio/vhost-shadow-virtqueue.c | 8 +- > hw/virtio/vhost-vdpa.c | 128 +++++++++++++------ > hw/virtio/vhost.c | 3 + > net/vhost-vdpa.c | 198 ++++++++++++++++++++++++----- > hw/virtio/trace-events | 1 + > 7 files changed, 273 insertions(+), 72 deletions(-) > > -- The migration works with SolidNET DPU. Tested-by: Alvaro Karsz