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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?8Wu0DG9CYNdXiD+XGXbEYiSYxAUu8zT/1FMT5w7/0vVHY+Rg1h5Od3t8QvyB?= =?us-ascii?Q?Ev+DmL+ExDsUyMAB4BB1O9SJfIw26LLGylBdRLNW2QhlLLN3nPiSD74Sl4Iw?= =?us-ascii?Q?V4kDewI67YjhV7WnC8af1+zDgmTXBQLdnwMOzslZ8y3R4HR50Nt/+U5o+lSm?= =?us-ascii?Q?gLH7p9J37w9zRS5tcdNW6+jbMS6rVzkbdBYLDfcAFogQe5b2ZVjwHLud+IPQ?= =?us-ascii?Q?fDkRTTw47TTnVjbJ6bJJMaGbjloND6+i27KQsmRJQfQ2zCJn1bkHLKC8QPeY?= =?us-ascii?Q?R/Cv7A4uFPWftrPCzGOvckWpIq33aJSlCoG2UNTSkhRDlJFk/OgcUyTO+V0U?= =?us-ascii?Q?GxuoKf+vk/b9nxp3XYtEepOUbXKOSyRyjeNx7G/q8WDPZ21cQlhTT/Ydud+A?= =?us-ascii?Q?tHyYvVJqdwgyeaHG2mw9NEm/AUOFPeWynaRDhtTVU60QFVo8YK7pFya43DLb?= =?us-ascii?Q?O/keEsNWGaBTs9yBmJxacvhV0DGKJBuwjFNcExw1JSj2qu5Z3AGigg/NO6ie?= =?us-ascii?Q?WD1VcGpSsE+Acllp/TUMYDQyl4wQ99A/hnQ5jApRpXo6NhrSYPjgEPZwEiKo?= =?us-ascii?Q?X9G0/cV+0sfsalrriHIkc2KRamLf2nkY3KQz0bfCnlc4OzsJ3rMgGuT3eIcH?= =?us-ascii?Q?wXZsZIyliTP9pENLDcn0bRvS7n2nre2F8ojuhZdFiD60iAas1VRnjSJhyw8f?= =?us-ascii?Q?sB6HcGX9WMQE/EcQY0GEQld/41GgswLM3u7qsAov6dYK9ul05xj3FupE5Dd9?= =?us-ascii?Q?7RuBDmJkKdDJ+dREOtoMV9L5cFwYkO1QSHAUDokdt2hR2GVmciWdHtjaMnmZ?= =?us-ascii?Q?hDwXd4TfCyRvQ6wuP3t/bCraI3KHkqRO3bU7Yq13YBAOin4P9mIfESLYp+a4?= =?us-ascii?Q?Mb2qurfu1MlXL9tVM8pe8I3TXZithn1L5NxiG2+eUmbIfBhz1Q2wmqWMVZKL?= =?us-ascii?Q?9SYUxiNTcE+J3aTJsPk0sUWWKGbc6mfhcB9fGg/Z/5xZVjC0oFCCqqVAjmrD?= =?us-ascii?Q?7KJi4mVnZ1/VzOSN+J1bu0p0ni6BWvJf/9LYZnFqQXU6OkHA4/VafKD1IiDQ?= =?us-ascii?Q?MvEy7yTc+I8F0n9XNyOpNLUdQsSbP49cvsKhMz7gqOy2zJGCrqAaRjyFcfZ2?= =?us-ascii?Q?M/Fn5ZI1rYROIWlTI8SgqiAfs8Mul6CvF5uphr7jITpzbJVwkL19t11pQDw9?= =?us-ascii?Q?ChQbINgZcGQFdWselCvInsC+iEwdhZJ/N/dVzuQ01yW7nyY3+Y2ATujq0BVW?= =?us-ascii?Q?soGHBhPtTIIXfH7pp+6X5zD0N5buEyPl6xBlU2Be5c4iJ/hb8o10ktOb49Ix?= =?us-ascii?Q?0XfHSWGS9aKwpORvXmkpO5TS?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8d184113-680e-4156-1628-08d97dc3b343 X-MS-Exchange-CrossTenant-AuthSource: BL0PR12MB5506.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Sep 2021 12:22:53.2902 (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: YCNyBtkcbbDJWdEtP0QJMs4m86Y4jgaXaEs/lEIZ7hRTN3Ty22FKg4UsCqYdANgx X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5109 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 22, 2021 at 09:23:34AM +0000, Tian, Kevin wrote: > > Providing an ioctl to bind to a normal VFIO container or group might > > allow a reasonable fallback in userspace.. > > I didn't get this point though. An error in binding already allows the > user to fall back to the group path. Why do we need introduce another > ioctl to explicitly bind to container via the nongroup interface? New userspace still needs a fallback path if it hits the 'try and fail'. Keeping the device FD open and just using a different ioctl to bind to a container/group FD, which new userspace can then obtain as a fallback, might be OK. Hard to see without going through the qemu parts, so maybe just keep it in mind Jason 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 X-Spam-Level: X-Spam-Status: No, score=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 15B6CC433F5 for ; Wed, 22 Sep 2021 12:23:03 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9F07A61268 for ; Wed, 22 Sep 2021 12:23:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 9F07A61268 Authentication-Results: mail.kernel.org; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Wed, Sep 22, 2021 at 09:23:34AM +0000, Tian, Kevin wrote: > > Providing an ioctl to bind to a normal VFIO container or group might > > allow a reasonable fallback in userspace.. > > I didn't get this point though. An error in binding already allows the > user to fall back to the group path. Why do we need introduce another > ioctl to explicitly bind to container via the nongroup interface? New userspace still needs a fallback path if it hits the 'try and fail'. Keeping the device FD open and just using a different ioctl to bind to a container/group FD, which new userspace can then obtain as a fallback, might be OK. Hard to see without going through the qemu parts, so maybe just keep it in mind Jason _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu