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 7F1ABC28B23 for ; Thu, 6 Mar 2025 14:23:31 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tqC8D-0005oL-Fr; Thu, 06 Mar 2025 09:23:25 -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 1tqC88-0005ZL-7A for qemu-devel@nongnu.org; Thu, 06 Mar 2025 09:23:21 -0500 Received: from mail-dm6nam10on2062e.outbound.protection.outlook.com ([2a01:111:f403:2413::62e] helo=NAM10-DM6-obe.outbound.protection.outlook.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tqC85-0002hn-F1 for qemu-devel@nongnu.org; Thu, 06 Mar 2025 09:23:19 -0500 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=kQeCxSsZC8r0IA0XnYKlG5A1AclOiJDKYjB9I/K+UXeEfKWDw9Ezx2jEC+Ol7YJR+ekQyrKt+9SdYGDeWZNvYobhXjCeAh7nbGCgW7yGVbC1T2hGb8s9VhaSvVDW2920XOR8RNmjsKlguf8FFmrfVbsGnljqJ+HMl3OuOdZbtM/B7Tvf7UFT3mx8TXjaI+qMzBHwLRlydWowYwX70hppEIYpU63mm/lSpccWAEPoDPhQOde2fxpPoQrcvPUOdoZYlQy3E9sB5iEJpzZbHV4Tn2bEAgWUaZvnw9YfSReCtaUjysWIbF4WxTIgtRUCactaftj7ViBdqM5+ROV4LG8KtQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=FdFIjpbCmIIC5JYF2U0qPdZHsfjw4C8KLHArbhxnBiQ=; b=gt5R+HVdUkVLwtmB4SzpNYIdUB67+5TvqHtro3Hw5W30qOrdgehkbigbsxD7dH2DGkNvzMCpjDXSegz+D265feiB2/3cU2ECRT/eDQ25iZb2qZJ8MH+tzSuPO9iV2NShbK0q9V/s1jnNzyGoc2WRBtgmT8af1iydolozXAWx2LazgW6jVEQS7aKf40V7tP3iYgcUOg5d6V41yR8232qxII2IJ/M6hR4Za+zMXztI03zy5RMFsRmWVtoC8lnq9VkbI9A55/qwcM+tGqOAztjoZCxaJ49IxY3MmOLKup/yHXyo2LBg7psWCPH8wTkPavXtsKIWhL5v4OQBRllJLFus7w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=FdFIjpbCmIIC5JYF2U0qPdZHsfjw4C8KLHArbhxnBiQ=; b=hMM5c6JX+Obq9aynYp511AVAwD35UKAfnh/Zm/d1VhmTv9m3l6f3y7t6Gc3D/XABsHI7gnUPkypU+fHRNBgq0iJjM40u/nfxsfEzkKjQNQ+kSGEfjQu1gjw9glyCEGB57Tr+nduxXUTBXbG8gL9109c4Jz1rTPX5RLygLHONRhuNBG0Ep8nJgkij656kwFBULmtw1muQ2H07vCudtlA0CAzCgeMc+oMBJ/vQ6KdrriZLe47IK1wWR+tjAcHo+tyjKGZnj2oxea0NDkfkL+bBw7tNfwbZ3srFiTVybVgRys+uRYKbo4ldApvi9V5Jg96VWQBnbKFW/cBx/yMxH3Gnqg== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from BL0PR12MB5538.namprd12.prod.outlook.com (2603:10b6:208:1c9::11) by BY5PR12MB4068.namprd12.prod.outlook.com (2603:10b6:a03:203::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8511.16; Thu, 6 Mar 2025 14:23:10 +0000 Received: from BL0PR12MB5538.namprd12.prod.outlook.com ([fe80::3699:352b:fbf8:b41d]) by BL0PR12MB5538.namprd12.prod.outlook.com ([fe80::3699:352b:fbf8:b41d%6]) with mapi id 15.20.8511.015; Thu, 6 Mar 2025 14:23:09 +0000 Message-ID: Date: Thu, 6 Mar 2025 16:23:04 +0200 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 30/36] vfio/migration: Multifd device state transfer support - send side To: "Maciej S. Szmigiero" , =?UTF-8?Q?C=C3=A9dric_Le_Goater?= , Peter Xu , Fabiano Rosas Cc: Alex Williamson , Eric Blake , Markus Armbruster , =?UTF-8?Q?Daniel_P_=2E_Berrang=C3=A9?= , Joao Martins , qemu-devel@nongnu.org References: <4d727e2e0435e0022d50004e474077632830e08d.1741124640.git.maciej.szmigiero@oracle.com> <629dff3c-865d-47d9-a01a-d212dfed1efb@nvidia.com> <97b87f22-b867-4282-ba13-efba16458859@maciej.szmigiero.name> <973268d4-85d6-4a17-ae76-2d20d8cfd7cb@redhat.com> <498a07aa-d539-46e6-90e9-8c41a59a6b2f@maciej.szmigiero.name> Content-Language: en-US From: Avihai Horon In-Reply-To: <498a07aa-d539-46e6-90e9-8c41a59a6b2f@maciej.szmigiero.name> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: LO4P123CA0387.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:18f::14) To BL0PR12MB5538.namprd12.prod.outlook.com (2603:10b6:208:1c9::11) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL0PR12MB5538:EE_|BY5PR12MB4068:EE_ X-MS-Office365-Filtering-Correlation-Id: 228a685c-b942-4e72-6152-08dd5cba6b58 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|376014|7416014; X-Microsoft-Antispam-Message-Info: =?utf-8?B?OEs4NXNNb2tsSGlaLzNUaVJYVDEwV1BoTFFxc2QzUXJBVVpmamNXOFhrYXFv?= =?utf-8?B?M1FlTFpoMlVEZkdTR2hudEovMEVyaG45NnFFaWVqNG9YRUtiVHcyRVhwT2N0?= =?utf-8?B?cmRQTDk3dHZIbzJqb3RWS3M4Zmg5VXJBMUVhOE92U0MzTHFlWnBtTHJxRVNE?= =?utf-8?B?YnFVK1V6MWVFWUxtMnBOT1BmTzlXcGN3d0pEWndZaXN2VnIzUEhEb1d0Mm43?= =?utf-8?B?UFU0NmY1NStNOElJSmg2ZEgxUzdCb29RUlZRazNqTnptRVEwRUJUWXZBdDYr?= =?utf-8?B?a3NzNHgrUjFjbTQ5Y1lzcnFDTzZiV28xZXJhRG8vc2VOUEJMT1pKdkxISTBH?= =?utf-8?B?ZG5qOFN6MDI4UHNMRDRPdTFSWDNlRU1ucWd3TldNMnEwSDRKaHA2Z0NpY1JS?= =?utf-8?B?d0lnVFB3S0RJT0tpZHVGeFN0V0RjMTN4L2JUbmdjdVRJSnVnUG80bUZOTHY0?= =?utf-8?B?MG9NRWM2M25vd2dpSy94WTVFR1doTDlyREM3STZHWjJjWDR0SEJiTWRNZWxD?= =?utf-8?B?eFJZcHhzY0ZSc2ZpMWJ5dkE1dmdzWTJKVzJPYUEyODNSSGNGNDR4dHBZSmh1?= =?utf-8?B?SnZlQlArdjAzeE5ncUdtKzJQVERUaGhxY3BhTEVUeHhoNVQreEdCSUh6RTdx?= =?utf-8?B?Z0tlUmtOWTFtS2pPU1c5VmJneTV4S21td1F1aXZZYnlBZGpaeEM2akhmRE1w?= =?utf-8?B?Slp0R2dvSkFmOEcrYUdaUkVFRTlnSG9lblZISGpybG8wbFdtdEY1L1ovOGhm?= =?utf-8?B?ZVFJK2FRMEVwMXA3VTVvUXRYam5rcVRGZmcyY2ZsQlE4bkJFZCtualZjalR3?= =?utf-8?B?VUNrQ3YvVFNGK2xOc2h2aUpTRVVYTnNIZlNNM1FUNHlFb2JlQ0V3MmpVMURw?= =?utf-8?B?YVZ6TWlRNDRyVng0cGU0VkJWVmdhOFloUDhvWlROQy9JRnVPaXRyb1N0dnQ2?= =?utf-8?B?S1l6MmRMWWlmVHc2OEY3WFd5eEdhTW0vcjE3S25SZm42cnorNTZTSDhFaWJF?= =?utf-8?B?M2lXbGhUNUhMVDU2SGdGdS9QM1lXQXE5NzBrYmVFQmRvaGJEaTBmSHoxNUFs?= =?utf-8?B?OE5NZmVVY2dNM2FxbnVVeU4zUG9CenB3ajdERjRsT0RrOU1NYkcxNVFJNlZo?= =?utf-8?B?dTBVQVA5bWNHcDY1SU1MNHZvcENEdGV1RU1qWXdnN3FQZ0ExNzRyTXRTK2Jy?= =?utf-8?B?NE5aWmZkUXlyQkVGM0cvNHEvYTMvQWZ0ZlFVQURhaEg5dVhUd0tldUVUekRP?= =?utf-8?B?SnpwZUVjOWNuOGhwcnZTTFVTV1htc1JhYkV0aUlrS21zeUJqeUhIZitaaUpP?= =?utf-8?B?aDZ0cWMxZGlHcU9zK1NtTE5uSlpNSlBCbGMzQlJhNVBRSlFjUVpvUFJVb3Rt?= =?utf-8?B?ZDVraklxZ0pwdVUvU0J6K0VYYXFIcXJWY2xEbUY4SWRXWUhLaC9XVkZRZlNz?= =?utf-8?B?VWIveWNQb1BEemZxVnZxelFMclA1dithUHJ4SnpGS1QyQU5mbTRzV3Y5VGFu?= =?utf-8?B?QnFxNjRRMFJaT3lRVHhnN2cyckhybnlvS0hBQkpOS2ZuVW8vTWNuWEZzdnVC?= =?utf-8?B?NWlMRmdxTWZhdlU2cVlFMFF1RHJSSWdxSVpubXV2S21HdW5KOWo5bTRGVkpi?= =?utf-8?B?RGRjZnhYWkJvYXVoQnhsYmJKS3FvNllyZ3BFTXc0bVNDTE5JWUNJMVZBWjJy?= =?utf-8?B?dVhxdHpLRDVxWGN5T0FZMnNIaDI1aFVQckxoYVFwNXBnMXZNNVFwVzNFVUpO?= =?utf-8?B?aDVNc0lYdnpUWDVBQkFiY2lQSG9HWCtXeHV2d01pbGxtRWdubWFlYUVWeHBn?= =?utf-8?B?eVpoNUd3MTN2elBjSFlHdVQ3WkRLRGczcmpORXNpdVpLeGdpMVBSOU9GSkJo?= =?utf-8?Q?7HiR3qPiEzrOq?= X-Forefront-Antispam-Report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:BL0PR12MB5538.namprd12.prod.outlook.com; PTR:; CAT:NONE; SFS:(13230040)(1800799024)(366016)(376014)(7416014); DIR:OUT; SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?aHZPU0JHVmd0V1BsZGMyeHRoZGJqMUdURyszUmZzekhycEsvUU1CakhtUDZO?= =?utf-8?B?RjlwRHB5R2pUczVxcDBsWXpVNWk0dTdMWmhBenhmdE9LZUJuZERuUkZXNWR6?= =?utf-8?B?dzZkR0NEd3NTNmFNMlFXMldLV0dqZERtWklBa1ZyZlIvM3JEelNZM3p0dUNB?= =?utf-8?B?a05TdXJzZWFQZzdkajFGemFyb2d3K2VXZ3lnRk05OG9mUGNoVHVHM25vWUFa?= =?utf-8?B?Z09XVy9HbWZnU000dzhFUndJdTZ2SCtZRTFFRVIvdVlUY2MwOXFKemEyYkgv?= =?utf-8?B?VDU3ajRJOTJRd1BJd2F0bWZSY1FtZithWk8xUXo3NEVoNG1mMmZMV2MzbmlU?= =?utf-8?B?WVllQjRVd2dwcUhicUZDRkZCVUNHMmV3TU54dEtzU2ZkREhrUEdwRDdXV0k5?= =?utf-8?B?R0YwVmoxcmtncHJBWUFBeHFCRjIvU2IzTmZWSVpJMnBRcXdWWWNYWDhpQWY0?= =?utf-8?B?ZnZwMmtCcXF4cWVNbGthZkROZUlVbEpxQktYT0pXMzJhYnU3azE0eU0veFFC?= =?utf-8?B?TlRSSWZTT2ZuckFaNXQwem9mWjBhMjNBSDIrTTFReEFQZURmcUhSbS9yTERE?= =?utf-8?B?VVhtM2ZNM01VUjVQbTRhQ21xTzlZOEJuTGo4SHNnRlhVTk5SaVJFUEh4R0h5?= =?utf-8?B?dGNueGU4YmNqRUxxQW1pRXlCb1p4ZVdxbnArWGRrRnZ0TFhQanRHekJ2c09t?= =?utf-8?B?THRUd3Q0N2tEcWsxTmxoMWwwZzRJOFZZTndGRmxYS3lIcm1QT0lYTU9HdHps?= =?utf-8?B?OENaYkJ3MDJGNWpqblRISVU3bTh3KytFL042N2Iwd1E2WXBBajJFaUN1OHpB?= =?utf-8?B?NG1Ka0FTekc5aGtVODNJeFRXN0lvcS85RDNGb0RPeHJaZmZCdGJYNnRIai9R?= =?utf-8?B?SzZaVVhVSmZ0RzdlQVJ0eGV1MVRKVEMxdWRsU0QwY1FvYW1HcVdhdkR4Yk5x?= =?utf-8?B?a1BFdXJzeDJTSTYwV05MQk1Ec1JOenlyeGdIYisrMjlNckg4WE1GQkxvcVhD?= =?utf-8?B?YVhvdW5jWkFoY1duWmZOcngzUGZIaWYrUmY5YTJtYVhIZ2trSUhvcmN1QUhx?= =?utf-8?B?bW0rSjZydFlOTGF2ODd5Rk1zbFlkOXFJUytQdmRCVE5FNW82cVRQOXEwU0RF?= =?utf-8?B?a2NtWEUzeTFxK2lIZXJSVGdwc2huNlN0TDd3RlRENnBReUZ0akF3TFEvdW45?= =?utf-8?B?eHpKN29OcXZ3TXRDMTNkMkF1NG9qMVNvT1NIWTRCT2VYTlFLRitiWGVmK1dM?= =?utf-8?B?SWhjbXROVEhrN2l6SXBEKzBOaDdCdSt4VzhGZFkxaFdkTTJSN0RoRXFSc3ly?= =?utf-8?B?MmIzeGpndWVjeEFwTWRYRDIwZDdnTU9ySEJBdVBaN2wxdWF5NVc1QVVXay8x?= =?utf-8?B?Z04vR1FpUEliYTNQZCtxRWNLWUVKNHBvbGRvdUpVMDBrOWkwOTNaQkhNcms0?= =?utf-8?B?MlBtYlh3N2hhd3Y5YzZlbDJ3aEg3S28vOFZoZUpCM21ibUE3OC96MzQvWGxF?= =?utf-8?B?S05KbHQ4RDdkM0tPVTByaXB5WVJkMVRJb2ZOUy9LS2lvWXhWSGswdXVlVENP?= =?utf-8?B?MVhSY3BNT0IvUW10ajVCMDZZM3VveGZGSlJwd2tQM0VpemxtSDVpRWd6Tnpu?= =?utf-8?B?d3J3WnJReHRTd3FHNkhTRk00V0svQTAwUWVNWW9Ob1BLbEgwVzdZNDlzckYx?= =?utf-8?B?YnJVNldtSTUrNm1LVU56NjVlZjVJWXVnSDVDK283Y2pjMzdhNHVMeldvbDNv?= =?utf-8?B?c2VjeER2d1lMSVVEVUVuUU8rYU5oMHZYS21TdmZsN3J4R0ozQzM1RGVjRm5s?= =?utf-8?B?RnE1QWJWT2RCbXU3UHpZSkFwN2YzWFh1WEpZOXRLVE96WWFsTU5YZUthTHU5?= =?utf-8?B?SWdSakl4TTRuUzVweFluaFhrSjkzNTRRdEpiTTFKNlJLYXBJeHdqOEkzSVVK?= =?utf-8?B?K3hiL2xyaERsTGk4TGEveVBlR3Q0bWZpVkt2SzNYQVJBeGF5NDk4eG9STWxD?= =?utf-8?B?TSt4MEpQVFU3dUs5Nno5SUptZXN6RmlFV2wxbzJqcmEzZUZmQWZQOUpZaGhD?= =?utf-8?B?WWh1WXVoU1RvNkV3U3krb1R3NVFsbXhoTmVFUzhuUStnWEZCdGN1VURnQS9B?= =?utf-8?Q?BK4uo0eJWVGZmoxpbBCM/lr+2?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 228a685c-b942-4e72-6152-08dd5cba6b58 X-MS-Exchange-CrossTenant-AuthSource: BL0PR12MB5538.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Mar 2025 14:23:09.9004 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: H0kgxnlaVIBS46EutkNkNBu1Y4KcfV9tbp+MswGbkmbLzSGs8qVWlyHumWdj6MPkPHVSiwyTVq5sY+EyT9czkQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR12MB4068 Received-SPF: softfail client-ip=2a01:111:f403:2413::62e; envelope-from=avihaih@nvidia.com; helo=NAM10-DM6-obe.outbound.protection.outlook.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, 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 06/03/2025 16:13, Maciej S. Szmigiero wrote: > External email: Use caution opening links or attachments > > > On 6.03.2025 14:37, Avihai Horon wrote: >> >> On 06/03/2025 12:32, Cédric Le Goater wrote: >>> External email: Use caution opening links or attachments >>> >>> >>> On 3/6/25 11:15, Maciej S. Szmigiero wrote: >>>> On 6.03.2025 07:47, Avihai Horon wrote: >>>>> >>>>> On 05/03/2025 0:03, Maciej S. Szmigiero wrote: >>>>>> External email: Use caution opening links or attachments >>>>>> >>>>>> >>>>>> From: "Maciej S. Szmigiero" >>>>>> >>>>>> Implement the multifd device state transfer via additional >>>>>> per-device >>>>>> thread inside save_live_complete_precopy_thread handler. >>>>>> >>>>>> Switch between doing the data transfer in the new handler and >>>>>> doing it >>>>>> in the old save_state handler depending if VFIO multifd transfer >>>>>> is enabled >>>>>> or not. >>>>>> >>>>>> Signed-off-by: Maciej S. Szmigiero >>>>>> --- >>>>>>   hw/vfio/migration-multifd.c   | 142 >>>>>> ++++++++++++++++++++++++++++++++++ >>>>>>   hw/vfio/migration-multifd.h   |   6 ++ >>>>>>   hw/vfio/migration.c           |  22 ++++-- >>>>>>   hw/vfio/trace-events          |   2 + >>>>>>   include/hw/vfio/vfio-common.h |   6 ++ >>>>>>   5 files changed, 172 insertions(+), 6 deletions(-) >>>>>> >>>>>> diff --git a/hw/vfio/migration-multifd.c >>>>>> b/hw/vfio/migration-multifd.c >>>>>> index 1d81233c755f..bfb9a72fa450 100644 >>>>>> --- a/hw/vfio/migration-multifd.c >>>>>> +++ b/hw/vfio/migration-multifd.c >>>>>> @@ -496,6 +496,148 @@ bool vfio_multifd_setup(VFIODevice >>>>>> *vbasedev, bool alloc_multifd, Error **errp) >>>>>>       return true; >>>>>>   } >>>>>> >>>>>> +void vfio_multifd_emit_dummy_eos(VFIODevice *vbasedev, QEMUFile *f) >>>>>> +{ >>>>>> +    assert(vfio_multifd_transfer_enabled(vbasedev)); >>>>>> + >>>>>> +    /* >>>>>> +     * Emit dummy NOP data on the main migration channel since >>>>>> the actual >>>>>> +     * device state transfer is done via multifd channels. >>>>>> +     */ >>>>>> +    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE); >>>>>> +} >>>>>> + >>>>>> +static bool >>>>>> +vfio_save_complete_precopy_thread_config_state(VFIODevice >>>>>> *vbasedev, >>>>>> +                                               char *idstr, >>>>>> +                                               uint32_t >>>>>> instance_id, >>>>>> +                                               uint32_t idx, >>>>>> +                                               Error **errp) >>>>>> +{ >>>>>> +    g_autoptr(QIOChannelBuffer) bioc = NULL; >>>>>> +    g_autoptr(QEMUFile) f = NULL; >>>>>> +    int ret; >>>>>> +    g_autofree VFIODeviceStatePacket *packet = NULL; >>>>>> +    size_t packet_len; >>>>>> + >>>>>> +    bioc = qio_channel_buffer_new(0); >>>>>> +    qio_channel_set_name(QIO_CHANNEL(bioc), >>>>>> "vfio-device-config-save"); >>>>>> + >>>>>> +    f = qemu_file_new_output(QIO_CHANNEL(bioc)); >>>>>> + >>>>>> +    if (vfio_save_device_config_state(f, vbasedev, errp)) { >>>>>> +        return false; >>>>>> +    } >>>>>> + >>>>>> +    ret = qemu_fflush(f); >>>>>> +    if (ret) { >>>>>> +        error_setg(errp, "%s: save config state flush failed: %d", >>>>>> +                   vbasedev->name, ret); >>>>>> +        return false; >>>>>> +    } >>>>>> + >>>>>> +    packet_len = sizeof(*packet) + bioc->usage; >>>>>> +    packet = g_malloc0(packet_len); >>>>>> +    packet->version = VFIO_DEVICE_STATE_PACKET_VER_CURRENT; >>>>>> +    packet->idx = idx; >>>>>> +    packet->flags = VFIO_DEVICE_STATE_CONFIG_STATE; >>>>> >>>>> The packet is sent on the wire. >>>>> Shouldn't we use cpu_to_be32() for version, idx and flags? Also >>>>> below in vfio_multifd_save_complete_precopy_thread(). >>>>> And then use be32_to_cpu() in patch #26 when receiving the packet? >>>> >>>> Is it even possible to migrate to a host with different endianess >>>> here? >>>> >>>> Also AFAIK big endian hosts barely exist today, is any of them even >>>> VFIO-capable? >>> >>> s390x is VFIO capable. VFIO PCI migration is not supported on these. >>> >> It is indeed a niche use case and not even applicable today, but if >> we want to add support for it after the release, we will have to add >> a compatibility option for older QEMUs. >> If we add support for it now, then we can avoid the compatibility >> option. >> >> It's a really small change and it can come even after the series is >> merged, as a fix. >> So IMHO it wouldn't hurt, for completeness. > > For sure, any such bit stream change will need re-testing the whole > VFIO migration. > > But I will be testing the queued buffers size limit anyway so it would > make > sense to test both at the same time. > > Wouldn't it make more sense, however, to squash this endianess change > already > to the relevant patches rather than to have such bit stream modifying > patch on the top? > > It would help prevent backporting mistakes - when someone forgets > about this last patch > and ends with a different bit stream. I agree. Whatever you and Cedric decide.