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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9C22C8303D for ; Fri, 4 Jul 2025 16:48:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 494556B805E; Fri, 4 Jul 2025 12:48:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4433E6B8059; Fri, 4 Jul 2025 12:48:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2EBBE6B805E; Fri, 4 Jul 2025 12:48:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 1A59A6B8059 for ; Fri, 4 Jul 2025 12:48:02 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id B225FC0186 for ; Fri, 4 Jul 2025 16:48:01 +0000 (UTC) X-FDA: 83627164362.07.2302954 Received: from NAM10-DM6-obe.outbound.protection.outlook.com (mail-dm6nam10on2053.outbound.protection.outlook.com [40.107.93.53]) by imf18.hostedemail.com (Postfix) with ESMTP id D91331C000D for ; Fri, 4 Jul 2025 16:47:58 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=SrUiBw5m; spf=pass (imf18.hostedemail.com: domain of jgg@nvidia.com designates 40.107.93.53 as permitted sender) smtp.mailfrom=jgg@nvidia.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); dmarc=pass (policy=reject) header.from=nvidia.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1751647679; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=TD3wqz5t6l8cmuXavrzHnmIxlUThqluL4jT85O2FMt4=; b=Lgx8mekGGXLvAvI9Vr6dTdZ5JELKNls4qhwmSZCs1ejnldxsbadTPssAMMbyfvLn28TioT 3M2rqWMLFWBNOFEzZHZETN4urJ06sm6j0yGeMsVp/D0bFOH56W1K60rIGRsvYVwKXlXTQ/ CEQOi3V6HIrsPnXzzKIrN+EmE/8sWEw= ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1751647679; a=rsa-sha256; cv=pass; b=O2h2qxsEvWOZnlri/cX1dKAm8vavduPBXnuxMhuQQ4cqC8ZFWsOZ3P2Nqmp5i0vZY6SMgV eymIZbddbHNo8j9FYiPxFgAN9QQCXuOenmO2I5IH0oT76bAJyGr0P0NeoFBTFMirbvSDNJ w+Y1BM7XEXbmJj9WDJ1D3OBI2fFToHY= ARC-Authentication-Results: i=2; imf18.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=SrUiBw5m; spf=pass (imf18.hostedemail.com: domain of jgg@nvidia.com designates 40.107.93.53 as permitted sender) smtp.mailfrom=jgg@nvidia.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); dmarc=pass (policy=reject) header.from=nvidia.com ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=qtUX7Nf8zPcYIazB34U7+EX8ub6kC3l4G/l8B7czg6v+kC28pC0C5fK1c73077iKA6dsgyq9BNJwgkA/7LeBhIbRk7KsVdI5vhWsq25t0rgJ3k2Ca4cuFy/4Gp27Bc0s0WofSF/yZV9H29MPxS+zEf+BeObUMpFZ9mLGeC9bswgGCG7F86SgeFfLBIofg3Zy5qtkac6u8trYbgeV2ZLk3VrUONDl92dlIzT1j0nbJ1enQ3N7DJxY/knSx7Af/bZMgmYgZ6vpD5PrdLFx5L/FfQui/fIoTGZnsiarF/Esy2S0CTDlljaQAKjt731FQFOzwa6sSoSuE6GhbMg83x9/Ag== 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=TD3wqz5t6l8cmuXavrzHnmIxlUThqluL4jT85O2FMt4=; b=Kq+wNQf1+iYnYw+3wlhWnUsqwINv3A6NI3hb3PNT7zujja4/MrsnrX8QquIyYCqNhYMG/YOCrCEDQkTlPU0G9n8C4pIsIKZJS6YDR12BmNMEmVsYNdX0cRXMk+fCm9gyUp8e0xBTnOAoK4Q3fWAMvs9YYUhRAS9GyubK9NzxWhshb2RZuT5NjEqYplIGhtLYNUn5J1m0QKbmj/6OzfBajkcATGqey6Bf0d3n1JdvreKyfPawCedqnDisVIVj+IcP62EobjG5Sw3q8IaRm0MDI6QzVfVU7PTtBZkTR43C2TlFNvRdwWLLvflUhA357heqCBZKdylUtaIiNyYOz67UZw== 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=TD3wqz5t6l8cmuXavrzHnmIxlUThqluL4jT85O2FMt4=; b=SrUiBw5mQaBpZvT6iLx/JqGirJNbD7zDkmr6ocuYrxvKeHQE0pvREEgTc8HLsy81l58yTdQsCgSJLUFBonW5AiVL0tHa3FOfJO+zTUCAjXrhYmDHqIQq/aCiw/F/PbytQSCKYzpYfYWAyQz7xZjAfn75zu8VgwcDaJhpILoYyshMzgOt2xN/xP6ZQbCAdqLC1po1N/yUYoXAf2RlAtWkALF+0dZahHHMs4V+87X+6oH7Ai3ftpXL8H4H0DDIOEVJtSxt1gxwC2ufRR3NZlDa4WfGH5/paYrbl+iaSmvzg+QOnXLiOfGBypehc7oH33QF2s2oGxZC7HWdddRfYOTKAw== Received: from CH3PR12MB8659.namprd12.prod.outlook.com (2603:10b6:610:17c::13) by LV8PR12MB9229.namprd12.prod.outlook.com (2603:10b6:408:191::14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8857.37; Fri, 4 Jul 2025 16:47:55 +0000 Received: from CH3PR12MB8659.namprd12.prod.outlook.com ([fe80::6eb6:7d37:7b4b:1732]) by CH3PR12MB8659.namprd12.prod.outlook.com ([fe80::6eb6:7d37:7b4b:1732%7]) with mapi id 15.20.8880.030; Fri, 4 Jul 2025 16:47:55 +0000 Date: Fri, 4 Jul 2025 13:47:50 -0300 From: Jason Gunthorpe To: Will Deacon Cc: David Hildenbrand , Ankit Agrawal , "maz@kernel.org" , "oliver.upton@linux.dev" , "joey.gouly@arm.com" , "suzuki.poulose@arm.com" , "yuzenghui@huawei.com" , "catalin.marinas@arm.com" , "ryan.roberts@arm.com" , "shahuang@redhat.com" , "lpieralisi@kernel.org" , "ddutile@redhat.com" , "seanjc@google.com" , Aniket Agashe , Neo Jia , Kirti Wankhede , Krishnakant Jaju , "Tarun Gupta (SW-GPU)" , Vikram Sethi , Andy Currid , Alistair Popple , John Hubbard , Dan Williams , Zhi Wang , Matt Ochs , Uday Dhoke , Dheeraj Nigam , "alex.williamson@redhat.com" , "sebastianene@google.com" , "coltonlewis@google.com" , "kevin.tian@intel.com" , "yi.l.liu@intel.com" , "ardb@kernel.org" , "akpm@linux-foundation.org" , "gshan@redhat.com" , "linux-mm@kvack.org" , "tabba@google.com" , "qperret@google.com" , "kvmarm@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "maobibo@loongson.cn" , "pbonzini@redhat.com" Subject: Re: [PATCH v9 3/6] KVM: arm64: Block cacheable PFNMAP mapping Message-ID: <20250704164750.GO1410929@nvidia.com> References: <20250621042111.3992-1-ankita@nvidia.com> <20250621042111.3992-4-ankita@nvidia.com> <20250630122501.GQ167785@nvidia.com> <4b06b163-e1ce-4c20-b878-4593bc86bf53@redhat.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: SN7PR04CA0009.namprd04.prod.outlook.com (2603:10b6:806:f2::14) To CH3PR12MB8659.namprd12.prod.outlook.com (2603:10b6:610:17c::13) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR12MB8659:EE_|LV8PR12MB9229:EE_ X-MS-Office365-Filtering-Correlation-Id: 71a96b2a-518f-4a48-886b-08ddbb1a85e3 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|1800799024|376014|7416014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?/LL579qW12v5c45Wqq4RvvKe99IVlO+U/D2pOam5kpJk/6/i9LQarhNMwHBa?= =?us-ascii?Q?ZNuN2+mcRWR2GtM2G1o45lRPYDWxeu/hBbnv16tV7dJNj0HxPxaR//o5YLFS?= =?us-ascii?Q?g1N1n8YOu65ipNq3riGSgTXl0mABqlWBApKWDWPjIRq6jju3LyI+eUyjKZ3o?= =?us-ascii?Q?jlp6ehhpGimu/PC7iXkiRESiHNQQzUroymiP5wDEcd1DjQVfy4BowlZyT/O2?= =?us-ascii?Q?nZWNnXJqqm/Ie+widhDQTcV+5UhBlpziD412SE7qAuZkCMjzmc7prO1iarT+?= =?us-ascii?Q?ZvpDoSlW0NvoA6b4gko52Kkr6RvrXFY5rkxnBrXH3smOfg3+AnV6FNLRnEAy?= =?us-ascii?Q?oSiyZVZiz20dfPU264OqQ9reA2xTPD0ZeMaByn/Xx3g6B0vbyHyPWCU2RE97?= =?us-ascii?Q?n8v6L78wvf87CvKFbsBVRLeRjh0qFAHZoWp4/P92rEAD2GH6O7H/rgEYPe3c?= =?us-ascii?Q?LCWa0MVpnnvT16djPBh+QtqDSyAWaYU8ayXFt4EJI+8BsgJyCiQcjXI9Zd3+?= =?us-ascii?Q?eS6G7l7GWOWLF3wS3s60pO40f443szMev7aIzrN64VCMMGUxVlpkQYPo1wM7?= =?us-ascii?Q?7F6S4xdb/yPQYaz3pzw4yvwutfL/CmY+P6OT/I66KjALIMdy4dxG+WDtwJi2?= =?us-ascii?Q?WHjgy25ycm4Ft1jo1eOzoYe6bSA/GjMJyEq+a36l4wzQd5RfTS7mlRTXY+tv?= =?us-ascii?Q?hjfL0ydrPO/2dfGV8iLcdoPHTBJFm/TWzxboDaawPNlCesQrl/aUbJOkXAog?= =?us-ascii?Q?J6LMObWHSK5gjRqSC+kACfFjTyuEtQrhzXtDUOQePsuAYuhBPimIpbczN+zA?= =?us-ascii?Q?wjzGEo6gZD5zOuGmdbz/ajI9APRC9Bmc6Bry2Ukp9o2DL/+RLgdSTHmUktsv?= =?us-ascii?Q?pexx679byI3xTiDPIy4iV1dXdeYOsQWsuSDpCziKaurZS2BZGwKkMs4hUd9W?= =?us-ascii?Q?UI+5krTNC6397sFjDys1bfJktU4W9KmqMN2snYQKUw/TChdD28IwMKQzJkLw?= =?us-ascii?Q?QOEzkHS/kKCdebe0WbMeg+5b/Hr+lbQ2B0vY4bZhd9aGohHRsW0z2TRWX6N4?= =?us-ascii?Q?oC47LAYFMvAvsAWSDaeJEmxuNc5oKQP34nRCo6yiKKlsneS5FDquUPGR3WjM?= =?us-ascii?Q?0WUF0PDcP7ccyRnKwd3FxzhYsURLLd//bpjWrEDj+r+kGJIQ1Ev8vaBzyWKe?= =?us-ascii?Q?AIUo7mNUPTyQksg8kGtnQ/stGX+7KX7tSE3erwwO2is4zKGViKNbo4XDRUsz?= =?us-ascii?Q?0Y93TrEt9vhxiBLsBrgeZ8MsD14JBA7NcxBwi15m5w2lBNFLW3DPVNBmJS2d?= =?us-ascii?Q?i9FOk0S6mZ0DuTdRvatwqcaCYDfaFMBi9YPwafrIu0f0DiibbghPC5WXYDdu?= =?us-ascii?Q?gnAcdUp4cBptzWKMVJ/vaYio0y+EBgB2kHYNjibVAgqFe/akqTcEIN3oRFW1?= =?us-ascii?Q?FAbfMFRhgIk=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH3PR12MB8659.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(1800799024)(376014)(7416014);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?FPPQThIvFUMRfvIkGZNU2SgKaqcvqH0j6FojBSafbfXhbDzdDGJUWZbDBVbO?= =?us-ascii?Q?NNbj7CMqyUxeC+4U03T4ZnmxG3wuHa3Qd5ZVXqAoooeXWcT4JxuHYhpY8Hp9?= =?us-ascii?Q?8shlGPP6m2oitoHqJmeXsX+23Z5LzJ4qzo9lZD9YyYsnl9xVWuo5cca4ET8U?= =?us-ascii?Q?VDyUntFtcQWEW5zclOVjxp/Y7yH8fYqKt5XuoIWsz4zY69qHKtt8OCwA4bKF?= =?us-ascii?Q?gp5OotAr6iZKH/SRdZImNw49W0k/wTrYM2h/PsjcWj8eB6XawFRWEzEn03uD?= =?us-ascii?Q?4AzdKYujDyoyzSpqkC9+4PaOHemxdMHnoVZ6pvFtX2EGXuW1yNv5bna7+er/?= =?us-ascii?Q?PkuBMT4EVvGLeFGNSWAIoxMRAiELxxvmkOvWtkW4/auHxZQvUYosrqrhSsAP?= =?us-ascii?Q?TP7a9A4ZiGso2EofWOG58typYgTbE0/2woVpeCFmpTD1W5QsoourAkP47H2N?= =?us-ascii?Q?JEwF+4gle9QUmVv90Jr2f5EEvPWQnSa0miWepZ3vYHsvcRkxrCbj3WoOrg6J?= =?us-ascii?Q?eUUdItLQpvuNwgkpopoRaXZWaOJRTbm2LFCTrWam+e3uILW7FQIxwadYz7dz?= =?us-ascii?Q?l5x7v6T216jl6ROnExNonWjarzeaB4FenWlk8Z7kN+bDuJyL2nwgoHNe5OMp?= =?us-ascii?Q?/22G+ylWHalmx78Ji2r376hhztQlDpAix4HhtA4IuFw+Kas6JoGUBQk4kTg2?= =?us-ascii?Q?D+EPXWrO63M8Eq181mthtJRG8FGY0VPSU4/kfFO6rXdUAyMilV4cPWY2YZUv?= =?us-ascii?Q?fGyiSQMy2v/JdZoxCAPz4QXUDwU7OXHA5rzHtTg/cU/QNxdsOCnOc4C8DlM3?= =?us-ascii?Q?5a7K7L1sXo5QJtj3cPPkOS/0BG6DbAapm5KpLtCubWHNMs8miBVSL8cmWUZm?= =?us-ascii?Q?7m0iMc+pT+fQXpHqndJab468Nt5PRcW1nOyN07Kz1V8UBq71Ugli9j5+kkdE?= =?us-ascii?Q?QApB8tCRViIdqMCq3bW8piOXKYqrFLoPvoQB3G+4WxuIBAjY8q011nqBngpR?= =?us-ascii?Q?WFJSjqYW1sr4nIyIGc0z1cHTCnsYMxbW7is1bCRIZ7+mxYuQFqOFAR54ZkGg?= =?us-ascii?Q?VSzIJ6YvLkGFTzuyxoiLR6SJbjhTEkwadl6kedTTjSbIi7YJz0LS98nrUQZJ?= =?us-ascii?Q?a6VkxgvkS5mx1iuDJwbKE9XJQd5+gWWtHzx4vrXcj5MJYLDo3SMBb6AFWHJj?= =?us-ascii?Q?DzpoIyFhFb7vAMlGpRjcwbLLyJKvQchx2B34j9uU9eGmVEs9DU7l1Fn7fQYO?= =?us-ascii?Q?RCmoVJ4E2SMrDRaoP4tgW5WDz3m/XbbfuPgjsslqMkVKCQIpZ5D80BgBIpwH?= =?us-ascii?Q?zhyyh0Wu3SrtS22DAIN95oIoPCVSTVwP8y/C/KlwXjAVg6BJSsuSzGVY8CFl?= =?us-ascii?Q?0my/88/7yKZ+yBuOvVc5ZS7mXpnWWqU9cywi9KbUPVVo6hTHPJ0s1X9DL/JF?= =?us-ascii?Q?WBSpiMRkeSzl3lYt+qeOZGeF9o7nflA4ji6L44yMVUXpmXcfovCj1+l4+8zx?= =?us-ascii?Q?1Z949lj3jPK0TS13Va9T5Lwm1QGfdAzc1gyV9eDrQXNlRoy31PCPPkWzy7d2?= =?us-ascii?Q?95rnF0QZO0rCVBil9Nsx4bD0TF3eo3qm1ML4pSFn?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 71a96b2a-518f-4a48-886b-08ddbb1a85e3 X-MS-Exchange-CrossTenant-AuthSource: CH3PR12MB8659.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Jul 2025 16:47:55.0998 (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: a0B9oPeow86rVXv+UUe/pYxDjqKDz9j0NLH+qzWQXCKDqLDe+y6TeCz7cmKa8pJT X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV8PR12MB9229 X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: D91331C000D X-Stat-Signature: 5bgam6dt97sw8rdoxk8ei8o1yjgb7xrr X-HE-Tag: 1751647678-322819 X-HE-Meta: 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 1b+Qo9+Y 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jul 04, 2025 at 05:04:17PM +0100, Will Deacon wrote: > On Fri, Jul 04, 2025 at 02:21:32PM +0200, David Hildenbrand wrote: > > On 30.06.25 14:25, Jason Gunthorpe wrote: > > > On Mon, Jun 30, 2025 at 01:56:43AM +0000, Ankit Agrawal wrote: > > > > > Sorry for the drive-by comment, but I was looking at this old series from > > > > > Paolo (look at the cover letter and patch 5): > > > > > > > > > > https://lore.kernel.org/r/20250109133817.314401-1-pbonzini@redhat.com > > > > > > > > > > in which he points out that the arm64 get_vma_page_shift() function > > > > > incorrectly assumes that a VM_PFNMAP VMA is physically contiguous, which > > > > > may not be the case if a driver calls remap_pfn_range() to mess around > > > > > with mappings within the VMA. I think that implies that the optimisation > > > > > in 2aa53d68cee6 ("KVM: arm64: Try stage2 block mapping for host device > > > > > MMIO") is unsound. > > > > > > > > Hm yeah, that does seem problematic. Perhaps we need a new > > > > vma flag that could help the driver communicate to the KVM that the > > > > mapping is contiguous and it can go ahead with the optimization? > > > > E.g. something similar to VM_ALLOW_ANY_UNCACHED. > > > > > > I think Paolo has the right direction - remove any attempts by KVM to > > > expand contiguity, it should only copy the primary's PTEs and rely on > > > the primary to discover contiguity. No new flags. > > > > 100% > > The part I don't understand, however, is that I can't see an MMU notifier > anywhere on the successful remap_pfn_range() path. So if a driver is > using that interface to change the mapping properties of a VM_PFNMAP VMA, > how do we ensure that the guest doesn't use whatever stale mappings it's > faulted in previously? Did I just miss something? Generally mmu notifiers are for invalidation, not used when establishing new mappings. It is not legal to use remap_pfn_range() to replace already mapped PTEs. It can only be used during a fop mmap callback to establish the first mapping during VMA creation. Thus there can be no present mapping cached in a secondary and no need to invalidate. To have dynamic mappings you have to use the fault path and a vmf_XX function - which only happens if the address is non-present, so again no invalidation. Jason