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 CD43ECAC581 for ; Mon, 8 Sep 2025 15:37:14 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uvduq-0007pD-1A; Mon, 08 Sep 2025 11:36:24 -0400 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 1uvduk-0007eR-Vh for qemu-devel@nongnu.org; Mon, 08 Sep 2025 11:36:18 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uvduh-0005HY-OM for qemu-devel@nongnu.org; Mon, 08 Sep 2025 11:36:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1757345760; 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: in-reply-to:in-reply-to:references:references; bh=/2z4WZjc2Qw7Pdj0ZxOVrwEMVV/HOnLvbPYbjiPri8k=; b=f2Rbm6ebnMbdB5D8cJHgmLbDltyenXVTDqo1FN6Ieum1Ymcdd+Pi5fSia8cItZKJE7w7j+ sb78uzpVDDRNCDxaqFmIqEeMV7Nwl9OzNQT13DvCqLJ9y4CnZz8M45h60AwYl6w8JFXkjZ 6b5EVL6+C/aiDfXoZJBU/xtSwu4GBUA= Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-594-eTZYaSIENnOmSTh70G13Ng-1; Mon, 08 Sep 2025 11:35:59 -0400 X-MC-Unique: eTZYaSIENnOmSTh70G13Ng-1 X-Mimecast-MFC-AGG-ID: eTZYaSIENnOmSTh70G13Ng_1757345758 Received: by mail-qk1-f199.google.com with SMTP id af79cd13be357-816a52d9a6bso169760585a.1 for ; Mon, 08 Sep 2025 08:35:59 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757345758; x=1757950558; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=/2z4WZjc2Qw7Pdj0ZxOVrwEMVV/HOnLvbPYbjiPri8k=; b=h1TbCq0sEtG3kinnovQumpnb4N9xU5vcOu5SKBQGP6/lgiTbI9ADMWqgdbqqz1t2DL 86MP2tOIs3HSWR6kqVlTzzhs8pWSjCfOekNH2xyxM/TFjshxICFY7qG6ml2CfSMLscZj i6LwDYnFZ99o7jqoE/T/4DcTi/JLtfUmk9TScqvsAgnEfV2ZEs9sbvIAa1s4OpTg7XZf OgBZUZZVw7XwBObPRP0/OMnmZZh3uNrT/jpNJ6edHJ70tqC3cFp2mOGwjqc0AYsc9VyX ByMZ5KYq2/ZeyG+i4JQfp7/3YjAi0jIxwXrO9NjknLYWPzTK/mT2NU2T/jRNibbUQZEv uWHA== X-Forwarded-Encrypted: i=1; AJvYcCWFtI36fF+eREQpqv0fIu/dY8phR7+wSuq1QrNUeDF8y8PKxYdQtf889tnh3w7ym37gOWWeZhJyCVaI@nongnu.org X-Gm-Message-State: AOJu0YwpVsYhFKpYBiLbIF4eYkUGy+8Dl4BxkL791INDFgYUGDuKJwAZ L4TiVkMb78mTxpgECjgGJE2KD4rO1T+Sc5aJp69uDiWJjO33H3CdZRocruOzKAXJzDvsImJmFxL 5S5vcopjGkIaq4eufJ9qUqbvKcdZPi9RWJj7DosVAWutjQlNbKRot2Tyu X-Gm-Gg: ASbGncuR6PwVtiGuT/2tesPIVZTxNQdZEQvz7fdGC3XFlWCIpNcdW+7EDgL/EapV2Zj oVIpN9eaO8BLb4lE/Js/ALqwetwY117Puc03zNnq/UmQ/oQFdWXORcnjntZr1N72aXSEeWK8bOe GQQqrKhLAwmTI6xtukyQZYr2OoT/h+sZsOQ92FOdlFv0grNaGr6eQgH0sB5m0Mu8UzomdgADon2 pbulY1fRUtT1fEH0KbrKVlbQy+/kLr56Ni4G6dYJ3EARmkEm/JRpMNfTdeUx25K/sqWTtCiCFPK DoOtUBKfGPfJIOmqDqh+z6u5EaqagIVq X-Received: by 2002:a05:620a:4609:b0:816:638f:4ab0 with SMTP id af79cd13be357-816638f4eebmr484521585a.27.1757345758214; Mon, 08 Sep 2025 08:35:58 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFeac9ERaUm6vN81GgYU2HhrgjfSVe6+tpZBCcuERZexbNLnH/CSDwkQHP6uHmLtUAv7q5Pfg== X-Received: by 2002:a05:620a:4609:b0:816:638f:4ab0 with SMTP id af79cd13be357-816638f4eebmr484516185a.27.1757345757560; Mon, 08 Sep 2025 08:35:57 -0700 (PDT) Received: from x1.local ([174.89.135.121]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4b48f62aa29sm105884081cf.11.2025.09.08.08.35.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Sep 2025 08:35:56 -0700 (PDT) Date: Mon, 8 Sep 2025 11:35:45 -0400 From: Peter Xu To: Vladimir Sementsov-Ogievskiy Cc: jasowang@redhat.com, qemu-devel@nongnu.org, leiyang@redhat.com, steven.sistare@oracle.com, yc-core@yandex-team.ru, mst@redhat.com, farosas@suse.de, eblake@redhat.com, armbru@redhat.com, thuth@redhat.com, philmd@linaro.org, berrange@redhat.com Subject: Re: [PATCH v3 4/9] qapi: add interface for local TAP migration Message-ID: References: <20250905135039.2202924-1-vsementsov@yandex-team.ru> <20250905135039.2202924-5-vsementsov@yandex-team.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250905135039.2202924-5-vsementsov@yandex-team.ru> Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-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 On Fri, Sep 05, 2025 at 04:50:34PM +0300, Vladimir Sementsov-Ogievskiy wrote: > diff --git a/qapi/migration.json b/qapi/migration.json > index 2387c21e9c..992a5b1e2b 100644 > --- a/qapi/migration.json > +++ b/qapi/migration.json > @@ -517,6 +517,12 @@ > # each RAM page. Requires a migration URI that supports seeking, > # such as a file. (since 9.0) > # > +# @local-tap: Migrate TAPs locally, keeping backend alive. Open file > +# descriptors and TAP-related state are migrated. Only may be > +# used when migration channel is unix socket. For target device > +# also @local-incoming option must be specified (since 10.2) > +# (since 10.2) IMHO we should move this into a per-device property, at least we need one there to still control the device behavior; we had a similar discussion recently on iterable virtio-net. But maybe this one is slightly special? Maybe the tap device needs to at least know whether in this specific migration, if we want to pass over FD or not (e.g. local upgrade, or remote _real_ migration)? If that's the case, we may consider providing a generic migration capability, like cap-fd-passing. Nowadays since Fabiano's moving migration capabilities all over to migration parameters, this one can start with a parameter instead of a capability. The problem with migration capability is (at least) that it can't by default ON on any machine types.. meanwhile it simply looks like identital to parameters except it's always bool. The high level rational is that we should never add a per-device cap flag into migration framework. Thanks, -- Peter Xu