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 F2A8EE95399 for ; Wed, 4 Feb 2026 13:04:42 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vncY9-00017C-BT; Wed, 04 Feb 2026 08:04:05 -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 1vncY7-00016v-Lb for qemu-devel@nongnu.org; Wed, 04 Feb 2026 08:04:03 -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 1vncY5-0005x6-DB for qemu-devel@nongnu.org; Wed, 04 Feb 2026 08:04:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770210238; 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=uvFGF7uTamspqHZ8i+2W1kwQkISFavwKH902UPdMx5E=; b=H618xcJwTYowZTQ191OgcM+cHKYU6R3lOG933Mc2sW/GkDsYhWDGfEYD/BNvNQfK1cM26T bJrFxcaoC8Pi7PCiH8h4yOknLodtDq57cTR7x3owqzGFSXwRAJ5ybSAI9R0aFLcwAIr8k9 G3TZzeVXQnskiy4GYFKvPdGC8zjlqXg= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-435-2uZ8xmV-NLeEuxQ31Pd5Yw-1; Wed, 04 Feb 2026 08:03:56 -0500 X-MC-Unique: 2uZ8xmV-NLeEuxQ31Pd5Yw-1 X-Mimecast-MFC-AGG-ID: 2uZ8xmV-NLeEuxQ31Pd5Yw_1770210235 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 159DD1891469; Wed, 4 Feb 2026 13:03:22 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.22]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 90FE518003F6; Wed, 4 Feb 2026 13:03:21 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 2A26521E692D; Wed, 04 Feb 2026 14:03:19 +0100 (CET) From: Markus Armbruster To: Avihai Horon Cc: , Alex Williamson , =?utf-8?Q?C=C3=A9dric?= Le Goater , Eric Blake Subject: Re: [PATCH] vfio/migration: Send migration event before device state transition In-Reply-To: <20260128105159.10282-1-avihaih@nvidia.com> (Avihai Horon's message of "Wed, 28 Jan 2026 12:51:59 +0200") References: <20260128105159.10282-1-avihaih@nvidia.com> Date: Wed, 04 Feb 2026 14:03:19 +0100 Message-ID: <87343gy82w.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@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, 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: qemu development 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 Avihai Horon writes: > Currently, VFIO device migration event is sent after the device state > transition has been completed. However, it may be useful to additionally > send a "prepare" event before the state transition, to notify users that > it's about to happen. > > For example, in some cases with heavy resource utilization, stopping the > VFIO device may take a long time. In time-sensitive scenarios, the > management application that consumes the event may be notified about the > state transition too late. > > To overcome this issue, send an additional "prepare" migration event > before the device state transition. > > Signed-off-by: Avihai Horon > --- > qapi/vfio.json | 33 +++++++++++++++++++++++++++++++++ > hw/vfio/migration.c | 18 +++++++++++++----- > 2 files changed, 46 insertions(+), 5 deletions(-) > > diff --git a/qapi/vfio.json b/qapi/vfio.json > index a1a9c5b673..de41211f1d 100644 > --- a/qapi/vfio.json > +++ b/qapi/vfio.json > @@ -66,3 +66,36 @@ > 'qom-path': 'str', > 'device-state': 'QapiVfioMigrationState' > } } > + > +## > +# @VFIO_MIGRATION_PREPARE: > +# > +# This event is emitted when a VFIO device migration state is about to > +# be changed. Note that even if this event is received for state X, > +# the VFIO device may transition to a different state if the original > +# state transition to X failed. > +# > +# @device-id: The device's id, if it has one. > +# > +# @qom-path: The device's QOM path. > +# > +# @device-state: The new device migration state that is about to be > +# changed. > +# > +# Since: 11.0 > +# > +# .. qmp-example:: > +# > +# <- { "timestamp": { "seconds": 1713771323, "microseconds": 212268 }, > +# "event": "VFIO_MIGRATION_PREPARE", > +# "data": { > +# "device-id": "vfio_dev1", > +# "qom-path": "/machine/peripheral/vfio_dev1", > +# "device-state": "stop" } } > +## > +{ 'event': 'VFIO_MIGRATION_PREPARE', > + 'data': { > + 'device-id': 'str', > + 'qom-path': 'str', > + 'device-state': 'QapiVfioMigrationState' > + } } The QAPI schema is fine, so Acked-by: Markus Armbruster Whether the event makes sense I have no idea. I'm leaving that judgement to the migration and VFIO maintainers.