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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1F15C433F5 for ; Mon, 25 Oct 2021 23:35:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B311460720 for ; Mon, 25 Oct 2021 23:35:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234889AbhJYXh1 (ORCPT ); Mon, 25 Oct 2021 19:37:27 -0400 Received: from mail-sn1anam02on2082.outbound.protection.outlook.com ([40.107.96.82]:38661 "EHLO NAM02-SN1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S231161AbhJYXh0 (ORCPT ); Mon, 25 Oct 2021 19:37:26 -0400 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=g59vw9tUtUI3ctM6iHtF0Um+esby8vH687sQHbB5MvvkrV/F+/hHy4LUdJz1DIrHU53ZWNU9Jg1y1ScCKUC3Sh0atL6kEyIeLwJ9ht0Eq1wp2fw24IWGLb4d3j9U5GEkLzT9HZ9O768KpWArF4GwPR7b0e+TMegPE4uIlbD21TfxuEe8Cl2IuJ6hbAD94z0+SqXICbw1bAwE3JSda0DkzNXhTfVZ00uxEKsx9D3+oNg1MM7NB1bo7w5I/QFyQVaAvvigEhvtYBzJbSCiztTVF6j3hxLsjX2d75k+YN5efr6k9Rn9yIWVBX67z4lQPil3B9EZ8TO+ZBOZ7P3Ili9OxQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; 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=SguOKE8G3wLlsuxpF9GsNrAeL2d6XVzpD7Q9A5I0s7U=; b=O27zqGdgox0ozM1Z0Kph4C0UC0p24uHZ+nSbfxXUlXAG64qsQkaahNtyMCuRLelTOgsRTBpA8KsTUjVzUiCrAOeQnyHWsHa4DJv/FmcuHVMfQDDZuZdLScoKKIC1OvyvIVOcqU+v5dvM0AlzqyLavX+a+F/uYcLc2OzfMYsSkaTX76NAGBbpNbzlMbxbze/+vM+Nc09oP7BBx67rB3qwE9CBKMysdIGLMaN7V2XnkMpkOYLpSLIxqG2MYdEglFwTVmMGQEO8KkQszlE+Zt+y9iwiK59VaRg2sHkqaC3QXY6mubMJb63UnS3c7zUYUKfUP8SAGyX7/9wOpgcNoG7JSw== 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=SguOKE8G3wLlsuxpF9GsNrAeL2d6XVzpD7Q9A5I0s7U=; b=gdV6vALxYvCU2lynkQbpo4jJRfKCawDbvA+Wg57hrePRYfnusOZmQfrjRFF/1U+hGYM3/p8th9b+/fnghVrQ0l2AdAn0dBfBYgWL4jWNYgzlVOWH84zodN4CctTRDKiVlG9oCsJgENoDjr3dDTszrymfnkkdaWoWKOB8wpODw7phkLyN4ZSOrKCTAM0o2jBR0+/1q2mL6goqXI/4PjC+mR0xVb7lATDpP0JW23pudYuZvXTsvsBnpINhzuHotigzxgkY3o8bBgxv6v5gXzOfnVUlDrOUpEYK6MAR28JnKdS99OdSUFflH7VgSFtahgft9S4WT1x94147nTixwf6rPw== Authentication-Results: intel.com; dkim=none (message not signed) header.d=none;intel.com; dmarc=none action=none header.from=nvidia.com; Received: from BL0PR12MB5506.namprd12.prod.outlook.com (52.135.46.150) by BL1PR12MB5253.namprd12.prod.outlook.com (13.101.93.118) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4628.15; Mon, 25 Oct 2021 23:35:01 +0000 Received: from BL0PR12MB5506.namprd12.prod.outlook.com ([fe80::e8af:232:915e:2f95]) by BL0PR12MB5506.namprd12.prod.outlook.com ([fe80::e8af:232:915e:2f95%8]) with mapi id 15.20.4628.020; Mon, 25 Oct 2021 23:35:01 +0000 Date: Mon, 25 Oct 2021 20:34:59 -0300 From: Jason Gunthorpe To: "Tian, Kevin" Cc: Alex Williamson , "Liu, Yi L" , "hch@lst.de" , "jasowang@redhat.com" , "joro@8bytes.org" , "jean-philippe@linaro.org" , "parav@mellanox.com" , "lkml@metux.net" , "pbonzini@redhat.com" , "lushenming@huawei.com" , "eric.auger@redhat.com" , "corbet@lwn.net" , "Raj, Ashok" , "yi.l.liu@linux.intel.com" , "Tian, Jun J" , "Wu, Hao" , "Jiang, Dave" , "jacob.jun.pan@linux.intel.com" , "kwankhede@nvidia.com" , "robin.murphy@arm.com" , "kvm@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "dwmw2@infradead.org" , "linux-kernel@vger.kernel.org" , "baolu.lu@linux.intel.com" , "david@gibson.dropbear.id.au" , "nicolinc@nvidia.com" Subject: Re: [RFC 10/20] iommu/iommufd: Add IOMMU_DEVICE_GET_INFO Message-ID: <20211025233459.GM2744544@nvidia.com> References: <20210923114219.GG964074@nvidia.com> <20210930222355.GH964074@nvidia.com> <20211014154259.GT2744544@nvidia.com> <20211021233036.GN2744544@nvidia.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: YTOPR0101CA0042.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b00:14::19) To BL0PR12MB5506.namprd12.prod.outlook.com (2603:10b6:208:1cb::22) MIME-Version: 1.0 Received: from mlx.ziepe.ca (206.223.160.26) by YTOPR0101CA0042.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b00:14::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4608.18 via Frontend Transport; Mon, 25 Oct 2021 23:35:01 +0000 Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1mf9UZ-001vAa-Cx; Mon, 25 Oct 2021 20:34:59 -0300 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: f4b06b24-bc6d-4f5e-6938-08d998101051 X-MS-TrafficTypeDiagnostic: BL1PR12MB5253: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:8273; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BL0PR12MB5506.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(366004)(107886003)(33656002)(316002)(9786002)(2906002)(26005)(186003)(4326008)(54906003)(1076003)(2616005)(7416002)(38100700002)(86362001)(9746002)(508600001)(66476007)(66556008)(6916009)(36756003)(5660300002)(83380400001)(426003)(8936002)(66946007)(8676002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?cPULKCTIhOfvacJS/CfTb5qFmGRSwk7OblABDqzTBq2CoS1NFdKpxg1WouNW?= =?us-ascii?Q?/4F3vGre+boBE5YFYNe3Mv6QjpnGtmBYDq21zM7N04YWHZEZLnTsbst/pD1k?= =?us-ascii?Q?8yrUVg9iWxTFgExl519C3YpXYFSiqaarw82AXYjyDUJtFKLO0U4Dnx+C4wal?= =?us-ascii?Q?VoTSOkTqzD5N9bpvN1kH3S53RpL7c7+HBdZz7qt8UmA7uH7cACpPJdT8IKRt?= =?us-ascii?Q?AubSwX8qgl/mF+Wc3bSTDeear+doUtA9Q+CzilOQ3TUP5OmTff9vJZP9cl7f?= =?us-ascii?Q?YhR0aIu040kXJf96EMYTImJGxrMlCwbINTavV6MQpFRJW/c+73WJciickb2X?= =?us-ascii?Q?Ef+/DLZXS6Hmi6+BCwTnsxkQ9wRZf5bUJyiSBz4he5S4T/0lc/R1iCzMUaw0?= =?us-ascii?Q?TpryU/0jbb4yAvYDNgWlQyXJBD7cvSoqOgoAvbqjn4swcT0WlQVtW7N/pk7j?= =?us-ascii?Q?ASt3Dve58MsymlcGqMBM3ejPd3Gdy7shMhzAxra1aiqLVTnz419whixIpSjl?= =?us-ascii?Q?NpY0EEEWbOeSuDhqPZqhuLwj3VU/ODEOsxQs7XEDLTWEZvgr5/0P0JmbRptd?= =?us-ascii?Q?SBWECSM1bVNqlEEHoO6H/bpqA4rnVmg9MCBATU9zbhxCgtQe1VjtmU34ksCz?= =?us-ascii?Q?6nUZYZ2Z+tAP+qX0L7t0Sm7X6e3zyxst951sGtJQzhof9svZWXWD4NonJvLf?= =?us-ascii?Q?ZN2xo0R6g7OLpKWpPC07cyfBmr2+hf4EnXsAkxC3Okb5P8IPQ/r/P0/TW/U0?= =?us-ascii?Q?icKAR7R+7x8CdiX/DWRo2EYh4FKTui4s6kOFFe/OrKHhFUIeYhiDgzgDdyJq?= =?us-ascii?Q?nQtXrOTXvtLybnMOTU2oGe4H8RuEug8ISK5wDvf/dJzkGtAjXyV0XAwDcp7l?= =?us-ascii?Q?H2+DFX1F34JwWZ1VA3EOXTXrIEdo9soTEmbKxjHcnIIiXJFF0ytpccNisz7x?= =?us-ascii?Q?zpWDBMU0Z3FD67ScM3nyDXZz9RdLMGzySeCkidP1UA3OadHQJ4OOin4oJ5wC?= =?us-ascii?Q?ku0ZrSlk1McOvZpIVWkG7OOF6sIcO0AIdzESBN+Y9DuvyZtuDQR53+GsgUtz?= =?us-ascii?Q?A+h9ZQT/CWGLh8EJa1GY538SFeFHpBaUnBVpt6OePky6osB2r9fGDE5Q75xB?= =?us-ascii?Q?EYf8WmmsqbKB5CBJLJNPIcA6D/0pRumWlQ+NSQBqSe7j6rGwtY8AFnWqpplq?= =?us-ascii?Q?ispzXSsRt3uc1D3pEF16GyNM6DI9QEK/2RzSZllZM8S/EuKT+4wr86WUvABo?= =?us-ascii?Q?WOIq9VEu8Lm5zbjrhib1u9gUY3DZWNfdSj5lwc6/4dcIu7KjtuViXaoCnk2n?= =?us-ascii?Q?Ryj4AUHclMYI81JFaZaCwVRANHeZForUc7hER8lmfJjSnwTlj65ytR5Cxw6V?= =?us-ascii?Q?UbeXbv2CwZjGI9s0qn/lHrBl8fZ6VO3lSbQD8NjJbagy+7QwTF0qpMe9BWnT?= =?us-ascii?Q?7thl8AvRRMAU5zFM6oRXqoYgAuQf8SKEt8nSBkYUnu2DOh6EkhncJ/Z7dqni?= =?us-ascii?Q?G0XVkQXovU98zpSID5uot6y+z1dQ8nmAwJ/uAdFFlT95Zj+gwzVIQzskkMHl?= =?us-ascii?Q?OCvr6xFvCclL4aqIwvA=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: f4b06b24-bc6d-4f5e-6938-08d998101051 X-MS-Exchange-CrossTenant-AuthSource: BL0PR12MB5506.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Oct 2021 23:35:01.2585 (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: yfN262F/VGGEyqwbTgrl7HZk0bPuS+69eqU6UVsddONR3Y0S3shR9Z803q+GwHkE X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5253 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Oct 22, 2021 at 03:08:06AM +0000, Tian, Kevin wrote: > > I have no idea what security model makes sense for wbinvd, that is the > > major question you have to answer. > > wbinvd flushes the entire cache in local cpu. It's more a performance > isolation problem but nothing can prevent it once the user is allowed > to call this ioctl. This is the main reason why wbinvd is a privileged > instruction and is emulated by kvm as a nop unless an assigned device > has no-snoop requirement. alternatively the user may call clflush > which is unprivileged and can invalidate a specific cache line, though > not efficient for flushing a big buffer. > > One tricky thing is that the process might be scheduled to different > cpus between writing buffers and calling wbinvd ioctl. Since wbvind > only has local behavior, it requires the ioctl to call wbinvd on all > cpus that this process has previously been scheduled on. That is such a hassle, you may want to re-open this with the kvm people as it seems ARM also has different behavior between VM and process here. The ideal is already not being met, so maybe we can keep special casing cache ops? > Is there any concern if iommufd also follows the same mechanism? > Currently looks preempt notifier is only used by kvm. Not sure whether > there is strong criteria around using it. and this local behavior may > not apply to all platforms (then better hidden behind arch callback?) I don't have any desire to see a performance cost to implement an ioctl that nothing will ever call just to satisify a idealized target from the kvm folks.. Jason