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 8873BC87FCA for ; Thu, 7 Aug 2025 13:14:31 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uk0R4-0008Vr-6q; Thu, 07 Aug 2025 09:13:34 -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 1uk0R2-0008Uw-PO for qemu-devel@nongnu.org; Thu, 07 Aug 2025 09:13:32 -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 1uk0Qz-0001Hw-Io for qemu-devel@nongnu.org; Thu, 07 Aug 2025 09:13:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1754572406; 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=VLFudbkZiFbI63E5uxV9T6D7dkpmszkegZG0OKRnABQ=; b=FQ2jKzwb6jENaBzLOd77Wfs+esfUSPSryX6Kad7KT7rQ+H/tFlwxyia2jdae5IQVSFhBIA 03Lrbp898FhcxI7DT1KIAIwrSj6MGJNQos0qqVav4aKZp+bItfNpomL/49XDAZW+H4DJLG D33Y2vrvRVoL+4n176B5bO3f1VAErqc= Received: from mail-yb1-f200.google.com (mail-yb1-f200.google.com [209.85.219.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-156-0odiTelUOcOlWCN80AuXLQ-1; Thu, 07 Aug 2025 09:13:24 -0400 X-MC-Unique: 0odiTelUOcOlWCN80AuXLQ-1 X-Mimecast-MFC-AGG-ID: 0odiTelUOcOlWCN80AuXLQ_1754572404 Received: by mail-yb1-f200.google.com with SMTP id 3f1490d57ef6-e8db89e6a38so1093675276.0 for ; Thu, 07 Aug 2025 06:13:24 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1754572404; x=1755177204; 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=VLFudbkZiFbI63E5uxV9T6D7dkpmszkegZG0OKRnABQ=; b=dIODeNLwBY8mXHAP3Ieg7Gf+6uv+gmg6xx7AW472+4Y071U6V9do0H1x6ZENOtPRMz nJXdxIEb0JpfHvhwLzbu8ySH1htkxerncxjsgi8nfqtEdGWRjltjwato2c3jPrOyHu7P hMRXWCDN9XnlztQUaXsoR0doucNqSC+eUpYbEq+xFP26UsM++grTASBr/0TIu3CqnKgx h3Hw8lNcVp7XiguLQkivBFYZrlsgtDb+nvDUQrtF78nMOxvqrFDoupP/tpIkBf3EWx0z FqAV3fOByznDenZzhLVkkYCfVXLyQBkpsSPhi8kAJV4bLrGI8Aq1pGxTiPECiNhx7bwh pMPA== X-Gm-Message-State: AOJu0YxYbNprWYqxv9ggngp0NWPjoPU96zVnXGcsGh5lnKwJlpiEA3Aw CJEDBw7Yrn24/h+pTHvnOP2Ne3JVsPc7xu1EbDjYK6Isd5ncjxw/ASTlPV383nfgRz3A0rWe9rM Ozqi+l8BczypZEW6p2F96GO9/fn5OsaY9dwhGDt5VkZXNGFDw5wF3WGB0 X-Gm-Gg: ASbGncvNjaD+Tfm0ajMwa9C7gbo8m7DLQjf20eWxViszQhDil/QppDma1Pa4KZqYB7D YkNUopUdzmUcR6UkIujtkGa1VZ9PA0d2sEBgSb8ZqJJ4KSDiQOQQge7nYQ4R0I9vrFqMxpGUbkK fPsp7iWwXhBoBgabcw2OZdy17iOK/DuqOIopzQ8dI39dJxaBF1rr5zG8IiB/T15DZrh/xQMURgo 1OUEJF6oLqVrhrZvtnuXmm5FRtjGB6fpLgxdNwkiVhjJcoA9ZBAUnto+q5068ZGjSikrr3CIo8R KIysxJ5flgvdTLxsoZmj7XpezrUJSzTt X-Received: by 2002:a05:6902:110e:b0:e90:1055:bcb8 with SMTP id 3f1490d57ef6-e90287ac601mr8258618276.20.1754572403614; Thu, 07 Aug 2025 06:13:23 -0700 (PDT) X-Google-Smtp-Source: AGHT+IF4k30Ftt7jPAk1jGvn+AbinuxaM0CAuib2M2byNx8DG4A9lFngboRqKG6/FodjlT5wEKd/Kw== X-Received: by 2002:a05:6902:110e:b0:e90:1055:bcb8 with SMTP id 3f1490d57ef6-e90287ac601mr8258586276.20.1754572403211; Thu, 07 Aug 2025 06:13:23 -0700 (PDT) Received: from x1.local ([174.89.135.171]) by smtp.gmail.com with ESMTPSA id 3f1490d57ef6-e8fd35a98eesm6364710276.0.2025.08.07.06.13.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Aug 2025 06:13:22 -0700 (PDT) Date: Thu, 7 Aug 2025 09:13:11 -0400 From: Peter Xu To: Jonah Palmer Cc: qemu-devel@nongnu.org, farosas@suse.de, eblake@redhat.com, armbru@redhat.com, jasowang@redhat.com, mst@redhat.com, si-wei.liu@oracle.com, eperezma@redhat.com, boris.ostrovsky@oracle.com Subject: Re: [RFC 1/6] migration: Add virtio-iterative capability Message-ID: References: <20250722124127.2497406-1-jonah.palmer@oracle.com> <20250722124127.2497406-2-jonah.palmer@oracle.com> <71a1cb1b-49b9-4a4c-aa6d-429aa3cf8a8a@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <71a1cb1b-49b9-4a4c-aa6d-429aa3cf8a8a@oracle.com> 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_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_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 Thu, Aug 07, 2025 at 08:50:38AM -0400, Jonah Palmer wrote: > > > On 8/6/25 11:58 AM, Peter Xu wrote: > > On Tue, Jul 22, 2025 at 12:41:22PM +0000, Jonah Palmer wrote: > > > Adds a new migration capability 'virtio-iterative' that will allow > > > virtio devices, where supported, to iteratively migrate configuration > > > changes that occur during the migration process. > > > > > > This capability is added to the validated capabilities list to ensure > > > both the source and destination support it before enabling. > > > > > > The capability defaults to off to maintain backward compatibility. > > > > > > To enable the capability via HMP: > > > (qemu) migrate_set_capability virtio-iterative on > > > > > > To enable the capability via QMP: > > > {"execute": "migrate-set-capabilities", "arguments": { > > > "capabilities": [ > > > { "capability": "virtio-iterative", "state": true } > > > ] > > > } > > > } > > > > > > Signed-off-by: Jonah Palmer > > > --- > > > migration/savevm.c | 1 + > > > qapi/migration.json | 7 ++++++- > > > 2 files changed, 7 insertions(+), 1 deletion(-) > > > > > > diff --git a/migration/savevm.c b/migration/savevm.c > > > index bb04a4520d..40a2189866 100644 > > > --- a/migration/savevm.c > > > +++ b/migration/savevm.c > > > @@ -279,6 +279,7 @@ static bool should_validate_capability(int capability) > > > switch (capability) { > > > case MIGRATION_CAPABILITY_X_IGNORE_SHARED: > > > case MIGRATION_CAPABILITY_MAPPED_RAM: > > > + case MIGRATION_CAPABILITY_VIRTIO_ITERATIVE: > > > return true; > > > default: > > > return false; > > > diff --git a/qapi/migration.json b/qapi/migration.json > > > index 4963f6ca12..8f042c3ba5 100644 > > > --- a/qapi/migration.json > > > +++ b/qapi/migration.json > > > @@ -479,6 +479,11 @@ > > > # each RAM page. Requires a migration URI that supports seeking, > > > # such as a file. (since 9.0) > > > # > > > +# @virtio-iterative: Enable iterative migration for virtio devices, if > > > +# the device supports it. When enabled, and where supported, virtio > > > +# devices will track and migrate configuration changes that may > > > +# occur during the migration process. (Since 10.1) > > > +# > > > > Having a migration capability to enable iterative support for a specific > > type of device sounds wrong. > > > > If virtio will be able to support iterative saves, it could provide the > > save_live_iterate() function. Any explanation why it needs to be a > > migration capability? > > > > It certainly doesn't have to be a migration capability. Perhaps it's better > as a per-device compatibility property? E.g.: > > -device virtio-net-pci,x-iterative-migration=on,... > > I was just thinking along the lines of not having this feature enabled by > default for backwards-compatibility (and something to toggle to compare > performance during development). > > Totally open to suggestions though. I wasn't really sure how best a > feature/capability like this should be introduced. Yep, for RFC is fine, if there'll be a formal patch please propose it as a device property whenever needed, thanks. -- Peter Xu