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=-7.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 F239DC433E0 for ; Fri, 5 Feb 2021 08:07:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AC3E664F9B for ; Fri, 5 Feb 2021 08:07:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231514AbhBEIGp (ORCPT ); Fri, 5 Feb 2021 03:06:45 -0500 Received: from mail-dm6nam12on2077.outbound.protection.outlook.com ([40.107.243.77]:63969 "EHLO NAM12-DM6-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S231491AbhBEIGg (ORCPT ); Fri, 5 Feb 2021 03:06:36 -0500 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=ccsR30c9mh806hq8iyhQmzLpFd52rqzlis6Ca9CX3qI8D5YGejerO8k3MZsNm/QIGq+kjWWHwnLsKZY/RH0b+cAn+jW24QZ7clPM0QAq28h3OD9BzAgkyy/0feOmrg8FzT3qmpRUZr6jNQBjyuDtKjz1BvwYRFOT35EUPK7s41nEsTWP+1oC/XrcwDb4NdJHdLdERn3M3cEe89kzMcHb65z0aYGSGQS9xhYTmKC358j8UNNDpulZSp+Gu2Vq247wsEkPT1TgVzBFdVY2cXxwmw6r8tSOiFN27LnfvsJEPm5ay52VJjUcm1OeIC5AAL8ZYu/BucX9P+eR7/G5he5EIg== 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-SenderADCheck; bh=JoJ/xwtY1C7gUbACDNAwK09L3m6Tafnh79HAKAyDpk4=; b=gj2LBeF6r26wipSOtFogSn5QU03RyEW95TWEYc9e4+WhB0sJHg0qr1DNZF98a9yCWNcyLa9pGc3AO3zRpxVecqm9/sA/+DbPyOk+dWPB9MO47bQRT3jEFoqEuLYRSaqebnaSe1K+XBqltSpD3Z5MBYZiLJ8ISv3nVe5EU/BFtPyBcCw0kBL18MV30tq8CH2H8BUqucEyqMJDEDTVz8a0jUDcLq7jF9ZvW6KecJTP573oB8cBy2txYmwwO3EmSmyLNsuHYFZwgDB8r0c+R6TwlblC642IGpi4NGE4FjQqKvDP/5TqtEVRzmy/7Uef5zbYL2/qRKAl27GmjQI/bvrNJg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=JoJ/xwtY1C7gUbACDNAwK09L3m6Tafnh79HAKAyDpk4=; b=IKdjN6P2IX4mYC5rqZECs+PGckLiBaLkVrN/ew1610aQt2jKux1A0WF/zD11X1e4EecTgT2Uv/V+tNl3NQO2h8TkERTTQnD2TwsmQTiy6uRVg2w4b9Jf6afeDWvM/u9MCgROu4kn9tg+NnCL6+TtWH5Arcemween+8H6AoQC5UY= Authentication-Results: lists.linaro.org; dkim=none (message not signed) header.d=none;lists.linaro.org; dmarc=none action=none header.from=amd.com; Received: from MN2PR12MB3775.namprd12.prod.outlook.com (2603:10b6:208:159::19) by MN2PR12MB4343.namprd12.prod.outlook.com (2603:10b6:208:26f::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3825.17; Fri, 5 Feb 2021 08:05:43 +0000 Received: from MN2PR12MB3775.namprd12.prod.outlook.com ([fe80::c1ff:dcf1:9536:a1f2]) by MN2PR12MB3775.namprd12.prod.outlook.com ([fe80::c1ff:dcf1:9536:a1f2%2]) with mapi id 15.20.3825.023; Fri, 5 Feb 2021 08:05:42 +0000 Subject: Re: [PATCH] RFC: dma-buf: Require VM_SPECIAL vma for mmap To: Jason Gunthorpe , Daniel Vetter Cc: DRI Development , Intel Graphics Development , Suren Baghdasaryan , Matthew Wilcox , John Stultz , Daniel Vetter , Sumit Semwal , "open list:DMA BUFFER SHARING FRAMEWORK" , "moderated list:DMA BUFFER SHARING FRAMEWORK" References: <20210203211948.2529297-1-daniel.vetter@ffwll.ch> <20210204161339.GX4718@ziepe.ca> <20210204183808.GY4718@ziepe.ca> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: <8e1de27f-9200-8748-730e-4bd7b94444b3@amd.com> Date: Fri, 5 Feb 2021 09:05:36 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 In-Reply-To: <20210204183808.GY4718@ziepe.ca> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [2a02:908:1252:fb60:be8a:bd56:1f94:86e7] X-ClientProxiedBy: AM0PR01CA0171.eurprd01.prod.exchangelabs.com (2603:10a6:208:aa::40) To MN2PR12MB3775.namprd12.prod.outlook.com (2603:10b6:208:159::19) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2a02:908:1252:fb60:be8a:bd56:1f94:86e7] (2a02:908:1252:fb60:be8a:bd56:1f94:86e7) by AM0PR01CA0171.eurprd01.prod.exchangelabs.com (2603:10a6:208:aa::40) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3825.19 via Frontend Transport; Fri, 5 Feb 2021 08:05:40 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: 674b2bbf-eb18-451b-44e5-08d8c9acd558 X-MS-TrafficTypeDiagnostic: MN2PR12MB4343: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:9508; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: zQ3wn6xDeOuwF7aSqdlAZbOZ/suqZ8EyzRujaFTWmAb8PzyLJrk1p+1peJfU+BZ8gNUWe0NhaEg1trajLJeczSXon4twESE8Y5AGhgMZpWd2HzjX0Jtjep5ANqsgPT9pPC2Kxf1UPsETyljyHpmC8PW4qhZv2wv6nLUVsT5od5MUwylTxWsbN6HhSAq68Aol2gjrmvNq5gGX7tFZ/l76d+CfX1CR95A/0EBkLQkzOtsx2m2l12fjKvLU7S7HLNyY4AQzJslkZwSbuSPWh/z0BRv8FEbqYwEvuazHA59i1GPL4HIwN5yPnmSY90Li7WJY7ZTmhNFhURcl9X0yqcyPevnTZ7A9PCxLL8bwywUoaMXQhQszoTdK+2qAAelbMSMWXHwR8LDNvtT9132cw1SHca8ichf9ns4zrNzHyL2KIrMG4fL0U/XLfv3qkpn5BgIDDIsr1xhWoU4IaQoUJ8twr0ocAzYUKRvnajrVKC5wvnZmZbATYCR44wrNon0Ewqnv9zqyPmWxIQE+ecz7SvaraRqfPPXaZ+JO2ymnChczaYsQdXHtBacYcE93Y0X17875c6W06DALGpXi4XTYWO3RqQ== X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:MN2PR12MB3775.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(376002)(366004)(396003)(136003)(39860400002)(346002)(186003)(6666004)(2906002)(86362001)(16526019)(6486002)(7416002)(2616005)(31696002)(31686004)(83380400001)(8676002)(53546011)(8936002)(36756003)(478600001)(66556008)(316002)(5660300002)(54906003)(110136005)(52116002)(66946007)(66476007)(4326008)(43740500002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?TjNUWksvTDdTVnhPY3RqM3p5dXdubEFKQklGMUZDU2JlcFdELzI0REx5OEVa?= =?utf-8?B?Z2krNENUYmcyeUc1WHptOGJiYkVIWVJZSkFJNGFQdUpOSVlUb01pbGdGY2ZP?= =?utf-8?B?TkJsOU1ubjhyQUsveG5ORng4NXh6MGJmLzAyL0JFUlpkYzNwR2EzRktxanRq?= =?utf-8?B?S1FEZEdGckNwTkF6SVdXT2ZpZlNoTmEzSmdkTldYTTRLSGo4YVdjNWk1Y1gy?= =?utf-8?B?QzhqczViZ2oveTlpV05McDJSbUdlTnkrZHpkYUNIcG5TS2htbjJsU2JUWmpy?= =?utf-8?B?SlhCVFRFWVY3T2NvM2pheUE5YlEzY29CS1hra1BtTHBPQlZsR3k0cUgyTTIv?= =?utf-8?B?N25PUTZZenZFWkRmc3hYSUVULzhoN2FIdFFrS29odkdqeEZFd3kvcDZTbWsw?= =?utf-8?B?NVcrNjdNYmFidTNpWENpY0dZRDd2MWRyUzFkWllkK3JRMGFBVzhYUnB6ZitB?= =?utf-8?B?blFqN3lHVUVqT0RxZVFxd0pLb3l5ckZSZlZ4T0pEeVBuTkgyaU5uZlA0L0pK?= =?utf-8?B?QVp3WFNuaWF4WUowNkQ0K2ZtTUIyejhCeGxrVGwrREFtTDlKUnBUYXdUZ0xq?= =?utf-8?B?RlR1MlBzTTVYcDNCanN1eEFKR1NRR0JVRXpGYTJsUytQZDlZYTNiWEpOT3ZC?= =?utf-8?B?Sy9YMlloMmJ3Y1RVMzdnQ1dQeHRiOGQ5cmhKRWZvSi9CZFFvaEV0UkZuZkJr?= =?utf-8?B?U2tmTzlrT3VvUlQvL3c1a0Y5enhuTXF0czYxUDFCTVlGZjJrc25VK1RCQXl6?= =?utf-8?B?Mms0azRHM2hGV0luQk43cURHdnhBUXlaakpSM01QL1AzSXczb3NtNGdYSURI?= =?utf-8?B?dDIrYnVzRXdiWkJNWDhWK1UwSjZvMXVmZS9NRXBBaEFhckg5eTZBRWVmdVJi?= =?utf-8?B?cmMvMTVmdDdSQVc4M0l3cW9QaXhDeGVXZ3dpRWxGbkEzK3JmWnBqeTZ3eEl5?= =?utf-8?B?UmFRVDMxRUhSSWJvWTlibHhyTjlkQ0EyUWNyUUcyVDV0ZWFVSnJ2S2V3QmEz?= =?utf-8?B?ckhQajNiNkVBUlVYakhRNHVCeWFGRFFiU3doY1dtb3VFZlJCNWZMRmpoeHdS?= =?utf-8?B?Y3VxTC9kenk1b2xlSERjZkErVGdLSHFZUmZKV256cWNWcWZPWlFrak5OdlFv?= =?utf-8?B?NllrVFB6UVU3ZHJzT1lvZG9kRFVhb2hYYjg2bElXanRtMHFObWJBam1iL016?= =?utf-8?B?cktYOURSVGRYTGtzcU1HV0JsdVowRXMyc1I2TTNhK3pDVzY0L1NqSktWZURV?= =?utf-8?B?MGRySmluUjFLb3pnUko0aHNPYmlsOW01czdaNzRmcXdzSE8zeWd5VjIxaVRH?= =?utf-8?B?UlhVdjVJUkw1cVlWRG92WlFGemlGN0xXQzZ4b0R4Y3ZleVFJMkhnbnN1UEJz?= =?utf-8?B?OWMvV1pXN0cyK2h6VlRDZm9EUUprRHh6dkdWZExrOWxCVlF0UVlMYXdhSkpp?= =?utf-8?B?cHN1RUhINk1SS0kyTDd0bVlVK1NBZlFrZUxERG93OFVSZ2swQ25xbkJCdFRU?= =?utf-8?B?SUJGRVlNWjE2dEV2Z0FYejR6dzNnOFVKQ2hhMml6a0ZSeHNsNWNRb1JCRDNZ?= =?utf-8?B?OHN2SUpOUGxiMlhrZHY2dklacFI5REs1QUFEUXgyTm9vcGRkeWVMRkJiVkU5?= =?utf-8?B?ci95UjByUVZ0MkFTbldma3ordTM1eklYTHRyMjc2VjNNNDJvNkdEc0ZkYXBH?= =?utf-8?B?dWNHTHplWEdQVTY2UnM2VEtXMG8rREh4UW5wRWgwSXg0STBFVWlRUWx0Y09P?= =?utf-8?B?MjdhWi9kUUduK212SHE3c0h4VDRyTGtTTGdzRXNJR0dBdTRwMzVIODJOVmlq?= =?utf-8?B?M3lOc0p1UEFjV0JJUHpzZ1YxZ2RlUk44QWd2ZWxYREh5UlBkczRzWXA0d1Nw?= =?utf-8?Q?WRW44iI6PkeF9?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 674b2bbf-eb18-451b-44e5-08d8c9acd558 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB3775.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Feb 2021 08:05:42.8732 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: vbdRAz0bszEhKM6J5A8SwXAT3ZKejnozVxX8mn3G8AB1OSqRVrPShYh2McvwImBg X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4343 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Am 04.02.21 um 19:38 schrieb Jason Gunthorpe: > On Thu, Feb 04, 2021 at 06:16:27PM +0100, Daniel Vetter wrote: >> On Thu, Feb 4, 2021 at 5:13 PM Jason Gunthorpe wrote: >>> On Wed, Feb 03, 2021 at 10:19:48PM +0100, Daniel Vetter wrote: >>>> tldr; DMA buffers aren't normal memory, expecting that you can use >>>> them like that (like calling get_user_pages works, or that they're >>>> accounting like any other normal memory) cannot be guaranteed. >>>> >>>> Since some userspace only runs on integrated devices, where all >>>> buffers are actually all resident system memory, there's a huge >>>> temptation to assume that a struct page is always present and useable >>>> like for any more pagecache backed mmap. This has the potential to >>>> result in a uapi nightmare. >>>> >>>> To stop this gap require that DMA buffer mmaps are VM_SPECIAL, which >>>> blocks get_user_pages and all the other struct page based >>>> infrastructure for everyone. In spirit this is the uapi counterpart to >>>> the kernel-internal CONFIG_DMABUF_DEBUG. >>> Fast gup needs the special flag set on the PTE as well.. Feels weird >>> to have a special VMA without also having special PTEs? >> There's kinda no convenient & cheap way to check for the pte_special >> flag. This here should at least catch accidental misuse, people >> building their own ptes we can't stop. Maybe we should exclude >> VM_MIXEDMAP to catch vm_insert_page in one of these. >> >> Hm looking at code I think we need to require VM_PFNMAP here to stop >> vm_insert_page. And looking at the various functions, that seems to be >> required (and I guess VM_IO is more for really funky architectures >> where io-space is somewhere else?). I guess I should check for >> VM_PFNMAP instead of VM_SPECIAL? > Well, you said the goal was to block GUP usage, that won't happen > without the PTE special flag, at least on x86 When is that special flag being set? > So, really, what you are saying is all dmabuf users should always use > vmf_insert_pfn_prot() or something similar - and never insert_page/etc? Exactly, yes. Christian. > It might make sense to check the vma flags in all the insert paths, eg > vm_insert_page() can't work with VMAs that should not have struct > pages in them (eg VM_SPECIAl, VM_PFNMAP, !VM_MIXEMAP if I understand > it right) > > At least as some VM debug option > > 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=-5.4 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 F0E6CC433E0 for ; Fri, 5 Feb 2021 08:05:49 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 966CD64F46 for ; Fri, 5 Feb 2021 08:05:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 966CD64F46 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=amd.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A65316F400; Fri, 5 Feb 2021 08:05:46 +0000 (UTC) Received: from NAM12-DM6-obe.outbound.protection.outlook.com (mail-dm6nam12on2059.outbound.protection.outlook.com [40.107.243.59]) by gabe.freedesktop.org (Postfix) with ESMTPS id 093ED6F3F9; Fri, 5 Feb 2021 08:05:45 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=ccsR30c9mh806hq8iyhQmzLpFd52rqzlis6Ca9CX3qI8D5YGejerO8k3MZsNm/QIGq+kjWWHwnLsKZY/RH0b+cAn+jW24QZ7clPM0QAq28h3OD9BzAgkyy/0feOmrg8FzT3qmpRUZr6jNQBjyuDtKjz1BvwYRFOT35EUPK7s41nEsTWP+1oC/XrcwDb4NdJHdLdERn3M3cEe89kzMcHb65z0aYGSGQS9xhYTmKC358j8UNNDpulZSp+Gu2Vq247wsEkPT1TgVzBFdVY2cXxwmw6r8tSOiFN27LnfvsJEPm5ay52VJjUcm1OeIC5AAL8ZYu/BucX9P+eR7/G5he5EIg== 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-SenderADCheck; bh=JoJ/xwtY1C7gUbACDNAwK09L3m6Tafnh79HAKAyDpk4=; b=gj2LBeF6r26wipSOtFogSn5QU03RyEW95TWEYc9e4+WhB0sJHg0qr1DNZF98a9yCWNcyLa9pGc3AO3zRpxVecqm9/sA/+DbPyOk+dWPB9MO47bQRT3jEFoqEuLYRSaqebnaSe1K+XBqltSpD3Z5MBYZiLJ8ISv3nVe5EU/BFtPyBcCw0kBL18MV30tq8CH2H8BUqucEyqMJDEDTVz8a0jUDcLq7jF9ZvW6KecJTP573oB8cBy2txYmwwO3EmSmyLNsuHYFZwgDB8r0c+R6TwlblC642IGpi4NGE4FjQqKvDP/5TqtEVRzmy/7Uef5zbYL2/qRKAl27GmjQI/bvrNJg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=JoJ/xwtY1C7gUbACDNAwK09L3m6Tafnh79HAKAyDpk4=; b=IKdjN6P2IX4mYC5rqZECs+PGckLiBaLkVrN/ew1610aQt2jKux1A0WF/zD11X1e4EecTgT2Uv/V+tNl3NQO2h8TkERTTQnD2TwsmQTiy6uRVg2w4b9Jf6afeDWvM/u9MCgROu4kn9tg+NnCL6+TtWH5Arcemween+8H6AoQC5UY= Authentication-Results: lists.linaro.org; dkim=none (message not signed) header.d=none;lists.linaro.org; dmarc=none action=none header.from=amd.com; Received: from MN2PR12MB3775.namprd12.prod.outlook.com (2603:10b6:208:159::19) by MN2PR12MB4343.namprd12.prod.outlook.com (2603:10b6:208:26f::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3825.17; Fri, 5 Feb 2021 08:05:43 +0000 Received: from MN2PR12MB3775.namprd12.prod.outlook.com ([fe80::c1ff:dcf1:9536:a1f2]) by MN2PR12MB3775.namprd12.prod.outlook.com ([fe80::c1ff:dcf1:9536:a1f2%2]) with mapi id 15.20.3825.023; Fri, 5 Feb 2021 08:05:42 +0000 Subject: Re: [PATCH] RFC: dma-buf: Require VM_SPECIAL vma for mmap To: Jason Gunthorpe , Daniel Vetter References: <20210203211948.2529297-1-daniel.vetter@ffwll.ch> <20210204161339.GX4718@ziepe.ca> <20210204183808.GY4718@ziepe.ca> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: <8e1de27f-9200-8748-730e-4bd7b94444b3@amd.com> Date: Fri, 5 Feb 2021 09:05:36 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 In-Reply-To: <20210204183808.GY4718@ziepe.ca> Content-Language: en-US X-Originating-IP: [2a02:908:1252:fb60:be8a:bd56:1f94:86e7] X-ClientProxiedBy: AM0PR01CA0171.eurprd01.prod.exchangelabs.com (2603:10a6:208:aa::40) To MN2PR12MB3775.namprd12.prod.outlook.com (2603:10b6:208:159::19) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2a02:908:1252:fb60:be8a:bd56:1f94:86e7] (2a02:908:1252:fb60:be8a:bd56:1f94:86e7) by AM0PR01CA0171.eurprd01.prod.exchangelabs.com (2603:10a6:208:aa::40) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3825.19 via Frontend Transport; Fri, 5 Feb 2021 08:05:40 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: 674b2bbf-eb18-451b-44e5-08d8c9acd558 X-MS-TrafficTypeDiagnostic: MN2PR12MB4343: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:9508; X-MS-Exchange-SenderADCheck: 1 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:MN2PR12MB3775.namprd12.prod.outlook.com; PTR:; CAT:NONE; SFS:(4636009)(376002)(366004)(396003)(136003)(39860400002)(346002)(186003)(6666004)(2906002)(86362001)(16526019)(6486002)(7416002)(2616005)(31696002)(31686004)(83380400001)(8676002)(53546011)(8936002)(36756003)(478600001)(66556008)(316002)(5660300002)(54906003)(110136005)(52116002)(66946007)(66476007)(4326008)(43740500002); DIR:OUT; SFP:1101; X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?TjNUWksvTDdTVnhPY3RqM3p5dXdubEFKQklGMUZDU2JlcFdELzI0REx5OEVa?= =?utf-8?B?Z2krNENUYmcyeUc1WHptOGJiYkVIWVJZSkFJNGFQdUpOSVlUb01pbGdGY2ZP?= =?utf-8?B?TkJsOU1ubjhyQUsveG5ORng4NXh6MGJmLzAyL0JFUlpkYzNwR2EzRktxanRq?= =?utf-8?B?S1FEZEdGckNwTkF6SVdXT2ZpZlNoTmEzSmdkTldYTTRLSGo4YVdjNWk1Y1gy?= =?utf-8?B?QzhqczViZ2oveTlpV05McDJSbUdlTnkrZHpkYUNIcG5TS2htbjJsU2JUWmpy?= =?utf-8?B?SlhCVFRFWVY3T2NvM2pheUE5YlEzY29CS1hra1BtTHBPQlZsR3k0cUgyTTIv?= =?utf-8?B?N25PUTZZenZFWkRmc3hYSUVULzhoN2FIdFFrS29odkdqeEZFd3kvcDZTbWsw?= =?utf-8?B?NVcrNjdNYmFidTNpWENpY0dZRDd2MWRyUzFkWllkK3JRMGFBVzhYUnB6ZitB?= =?utf-8?B?blFqN3lHVUVqT0RxZVFxd0pLb3l5ckZSZlZ4T0pEeVBuTkgyaU5uZlA0L0pK?= =?utf-8?B?QVp3WFNuaWF4WUowNkQ0K2ZtTUIyejhCeGxrVGwrREFtTDlKUnBUYXdUZ0xq?= =?utf-8?B?RlR1MlBzTTVYcDNCanN1eEFKR1NRR0JVRXpGYTJsUytQZDlZYTNiWEpOT3ZC?= =?utf-8?B?Sy9YMlloMmJ3Y1RVMzdnQ1dQeHRiOGQ5cmhKRWZvSi9CZFFvaEV0UkZuZkJr?= =?utf-8?B?U2tmTzlrT3VvUlQvL3c1a0Y5enhuTXF0czYxUDFCTVlGZjJrc25VK1RCQXl6?= =?utf-8?B?Mms0azRHM2hGV0luQk43cURHdnhBUXlaakpSM01QL1AzSXczb3NtNGdYSURI?= =?utf-8?B?dDIrYnVzRXdiWkJNWDhWK1UwSjZvMXVmZS9NRXBBaEFhckg5eTZBRWVmdVJi?= =?utf-8?B?cmMvMTVmdDdSQVc4M0l3cW9QaXhDeGVXZ3dpRWxGbkEzK3JmWnBqeTZ3eEl5?= =?utf-8?B?UmFRVDMxRUhSSWJvWTlibHhyTjlkQ0EyUWNyUUcyVDV0ZWFVSnJ2S2V3QmEz?= =?utf-8?B?ckhQajNiNkVBUlVYakhRNHVCeWFGRFFiU3doY1dtb3VFZlJCNWZMRmpoeHdS?= =?utf-8?B?Y3VxTC9kenk1b2xlSERjZkErVGdLSHFZUmZKV256cWNWcWZPWlFrak5OdlFv?= =?utf-8?B?NllrVFB6UVU3ZHJzT1lvZG9kRFVhb2hYYjg2bElXanRtMHFObWJBam1iL016?= =?utf-8?B?cktYOURSVGRYTGtzcU1HV0JsdVowRXMyc1I2TTNhK3pDVzY0L1NqSktWZURV?= =?utf-8?B?MGRySmluUjFLb3pnUko0aHNPYmlsOW01czdaNzRmcXdzSE8zeWd5VjIxaVRH?= =?utf-8?B?UlhVdjVJUkw1cVlWRG92WlFGemlGN0xXQzZ4b0R4Y3ZleVFJMkhnbnN1UEJz?= =?utf-8?B?OWMvV1pXN0cyK2h6VlRDZm9EUUprRHh6dkdWZExrOWxCVlF0UVlMYXdhSkpp?= =?utf-8?B?cHN1RUhINk1SS0kyTDd0bVlVK1NBZlFrZUxERG93OFVSZ2swQ25xbkJCdFRU?= =?utf-8?B?SUJGRVlNWjE2dEV2Z0FYejR6dzNnOFVKQ2hhMml6a0ZSeHNsNWNRb1JCRDNZ?= =?utf-8?B?OHN2SUpOUGxiMlhrZHY2dklacFI5REs1QUFEUXgyTm9vcGRkeWVMRkJiVkU5?= =?utf-8?B?ci95UjByUVZ0MkFTbldma3ordTM1eklYTHRyMjc2VjNNNDJvNkdEc0ZkYXBH?= =?utf-8?B?dWNHTHplWEdQVTY2UnM2VEtXMG8rREh4UW5wRWgwSXg0STBFVWlRUWx0Y09P?= =?utf-8?B?MjdhWi9kUUduK212SHE3c0h4VDRyTGtTTGdzRXNJR0dBdTRwMzVIODJOVmlq?= =?utf-8?B?M3lOc0p1UEFjV0JJUHpzZ1YxZ2RlUk44QWd2ZWxYREh5UlBkczRzWXA0d1Nw?= =?utf-8?Q?WRW44iI6PkeF9?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 674b2bbf-eb18-451b-44e5-08d8c9acd558 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB3775.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Feb 2021 08:05:42.8732 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: vbdRAz0bszEhKM6J5A8SwXAT3ZKejnozVxX8mn3G8AB1OSqRVrPShYh2McvwImBg X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4343 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Intel Graphics Development , Matthew Wilcox , "moderated list:DMA BUFFER SHARING FRAMEWORK" , DRI Development , Daniel Vetter , Suren Baghdasaryan , "open list:DMA BUFFER SHARING FRAMEWORK" Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Am 04.02.21 um 19:38 schrieb Jason Gunthorpe: > On Thu, Feb 04, 2021 at 06:16:27PM +0100, Daniel Vetter wrote: >> On Thu, Feb 4, 2021 at 5:13 PM Jason Gunthorpe wrote: >>> On Wed, Feb 03, 2021 at 10:19:48PM +0100, Daniel Vetter wrote: >>>> tldr; DMA buffers aren't normal memory, expecting that you can use >>>> them like that (like calling get_user_pages works, or that they're >>>> accounting like any other normal memory) cannot be guaranteed. >>>> >>>> Since some userspace only runs on integrated devices, where all >>>> buffers are actually all resident system memory, there's a huge >>>> temptation to assume that a struct page is always present and useable >>>> like for any more pagecache backed mmap. This has the potential to >>>> result in a uapi nightmare. >>>> >>>> To stop this gap require that DMA buffer mmaps are VM_SPECIAL, which >>>> blocks get_user_pages and all the other struct page based >>>> infrastructure for everyone. In spirit this is the uapi counterpart to >>>> the kernel-internal CONFIG_DMABUF_DEBUG. >>> Fast gup needs the special flag set on the PTE as well.. Feels weird >>> to have a special VMA without also having special PTEs? >> There's kinda no convenient & cheap way to check for the pte_special >> flag. This here should at least catch accidental misuse, people >> building their own ptes we can't stop. Maybe we should exclude >> VM_MIXEDMAP to catch vm_insert_page in one of these. >> >> Hm looking at code I think we need to require VM_PFNMAP here to stop >> vm_insert_page. And looking at the various functions, that seems to be >> required (and I guess VM_IO is more for really funky architectures >> where io-space is somewhere else?). I guess I should check for >> VM_PFNMAP instead of VM_SPECIAL? > Well, you said the goal was to block GUP usage, that won't happen > without the PTE special flag, at least on x86 When is that special flag being set? > So, really, what you are saying is all dmabuf users should always use > vmf_insert_pfn_prot() or something similar - and never insert_page/etc? Exactly, yes. Christian. > It might make sense to check the vma flags in all the insert paths, eg > vm_insert_page() can't work with VMAs that should not have struct > pages in them (eg VM_SPECIAl, VM_PFNMAP, !VM_MIXEMAP if I understand > it right) > > At least as some VM debug option > > Jason _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel 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=-5.4 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 598E5C433E0 for ; Fri, 5 Feb 2021 08:05:47 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 E6D5564F46 for ; Fri, 5 Feb 2021 08:05:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E6D5564F46 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=amd.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 45A5D6F3F9; Fri, 5 Feb 2021 08:05:46 +0000 (UTC) Received: from NAM12-DM6-obe.outbound.protection.outlook.com (mail-dm6nam12on2059.outbound.protection.outlook.com [40.107.243.59]) by gabe.freedesktop.org (Postfix) with ESMTPS id 093ED6F3F9; Fri, 5 Feb 2021 08:05:45 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=ccsR30c9mh806hq8iyhQmzLpFd52rqzlis6Ca9CX3qI8D5YGejerO8k3MZsNm/QIGq+kjWWHwnLsKZY/RH0b+cAn+jW24QZ7clPM0QAq28h3OD9BzAgkyy/0feOmrg8FzT3qmpRUZr6jNQBjyuDtKjz1BvwYRFOT35EUPK7s41nEsTWP+1oC/XrcwDb4NdJHdLdERn3M3cEe89kzMcHb65z0aYGSGQS9xhYTmKC358j8UNNDpulZSp+Gu2Vq247wsEkPT1TgVzBFdVY2cXxwmw6r8tSOiFN27LnfvsJEPm5ay52VJjUcm1OeIC5AAL8ZYu/BucX9P+eR7/G5he5EIg== 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-SenderADCheck; bh=JoJ/xwtY1C7gUbACDNAwK09L3m6Tafnh79HAKAyDpk4=; b=gj2LBeF6r26wipSOtFogSn5QU03RyEW95TWEYc9e4+WhB0sJHg0qr1DNZF98a9yCWNcyLa9pGc3AO3zRpxVecqm9/sA/+DbPyOk+dWPB9MO47bQRT3jEFoqEuLYRSaqebnaSe1K+XBqltSpD3Z5MBYZiLJ8ISv3nVe5EU/BFtPyBcCw0kBL18MV30tq8CH2H8BUqucEyqMJDEDTVz8a0jUDcLq7jF9ZvW6KecJTP573oB8cBy2txYmwwO3EmSmyLNsuHYFZwgDB8r0c+R6TwlblC642IGpi4NGE4FjQqKvDP/5TqtEVRzmy/7Uef5zbYL2/qRKAl27GmjQI/bvrNJg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=JoJ/xwtY1C7gUbACDNAwK09L3m6Tafnh79HAKAyDpk4=; b=IKdjN6P2IX4mYC5rqZECs+PGckLiBaLkVrN/ew1610aQt2jKux1A0WF/zD11X1e4EecTgT2Uv/V+tNl3NQO2h8TkERTTQnD2TwsmQTiy6uRVg2w4b9Jf6afeDWvM/u9MCgROu4kn9tg+NnCL6+TtWH5Arcemween+8H6AoQC5UY= Authentication-Results: lists.linaro.org; dkim=none (message not signed) header.d=none;lists.linaro.org; dmarc=none action=none header.from=amd.com; Received: from MN2PR12MB3775.namprd12.prod.outlook.com (2603:10b6:208:159::19) by MN2PR12MB4343.namprd12.prod.outlook.com (2603:10b6:208:26f::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3825.17; Fri, 5 Feb 2021 08:05:43 +0000 Received: from MN2PR12MB3775.namprd12.prod.outlook.com ([fe80::c1ff:dcf1:9536:a1f2]) by MN2PR12MB3775.namprd12.prod.outlook.com ([fe80::c1ff:dcf1:9536:a1f2%2]) with mapi id 15.20.3825.023; Fri, 5 Feb 2021 08:05:42 +0000 To: Jason Gunthorpe , Daniel Vetter References: <20210203211948.2529297-1-daniel.vetter@ffwll.ch> <20210204161339.GX4718@ziepe.ca> <20210204183808.GY4718@ziepe.ca> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: <8e1de27f-9200-8748-730e-4bd7b94444b3@amd.com> Date: Fri, 5 Feb 2021 09:05:36 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 In-Reply-To: <20210204183808.GY4718@ziepe.ca> Content-Language: en-US X-Originating-IP: [2a02:908:1252:fb60:be8a:bd56:1f94:86e7] X-ClientProxiedBy: AM0PR01CA0171.eurprd01.prod.exchangelabs.com (2603:10a6:208:aa::40) To MN2PR12MB3775.namprd12.prod.outlook.com (2603:10b6:208:159::19) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2a02:908:1252:fb60:be8a:bd56:1f94:86e7] (2a02:908:1252:fb60:be8a:bd56:1f94:86e7) by AM0PR01CA0171.eurprd01.prod.exchangelabs.com (2603:10a6:208:aa::40) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3825.19 via Frontend Transport; Fri, 5 Feb 2021 08:05:40 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: 674b2bbf-eb18-451b-44e5-08d8c9acd558 X-MS-TrafficTypeDiagnostic: MN2PR12MB4343: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:9508; X-MS-Exchange-SenderADCheck: 1 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:MN2PR12MB3775.namprd12.prod.outlook.com; PTR:; CAT:NONE; SFS:(4636009)(376002)(366004)(396003)(136003)(39860400002)(346002)(186003)(6666004)(2906002)(86362001)(16526019)(6486002)(7416002)(2616005)(31696002)(31686004)(83380400001)(8676002)(53546011)(8936002)(36756003)(478600001)(66556008)(316002)(5660300002)(54906003)(110136005)(52116002)(66946007)(66476007)(4326008)(43740500002); DIR:OUT; SFP:1101; X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?TjNUWksvTDdTVnhPY3RqM3p5dXdubEFKQklGMUZDU2JlcFdELzI0REx5OEVa?= =?utf-8?B?Z2krNENUYmcyeUc1WHptOGJiYkVIWVJZSkFJNGFQdUpOSVlUb01pbGdGY2ZP?= =?utf-8?B?TkJsOU1ubjhyQUsveG5ORng4NXh6MGJmLzAyL0JFUlpkYzNwR2EzRktxanRq?= =?utf-8?B?S1FEZEdGckNwTkF6SVdXT2ZpZlNoTmEzSmdkTldYTTRLSGo4YVdjNWk1Y1gy?= =?utf-8?B?QzhqczViZ2oveTlpV05McDJSbUdlTnkrZHpkYUNIcG5TS2htbjJsU2JUWmpy?= =?utf-8?B?SlhCVFRFWVY3T2NvM2pheUE5YlEzY29CS1hra1BtTHBPQlZsR3k0cUgyTTIv?= =?utf-8?B?N25PUTZZenZFWkRmc3hYSUVULzhoN2FIdFFrS29odkdqeEZFd3kvcDZTbWsw?= =?utf-8?B?NVcrNjdNYmFidTNpWENpY0dZRDd2MWRyUzFkWllkK3JRMGFBVzhYUnB6ZitB?= =?utf-8?B?blFqN3lHVUVqT0RxZVFxd0pLb3l5ckZSZlZ4T0pEeVBuTkgyaU5uZlA0L0pK?= =?utf-8?B?QVp3WFNuaWF4WUowNkQ0K2ZtTUIyejhCeGxrVGwrREFtTDlKUnBUYXdUZ0xq?= =?utf-8?B?RlR1MlBzTTVYcDNCanN1eEFKR1NRR0JVRXpGYTJsUytQZDlZYTNiWEpOT3ZC?= =?utf-8?B?Sy9YMlloMmJ3Y1RVMzdnQ1dQeHRiOGQ5cmhKRWZvSi9CZFFvaEV0UkZuZkJr?= =?utf-8?B?U2tmTzlrT3VvUlQvL3c1a0Y5enhuTXF0czYxUDFCTVlGZjJrc25VK1RCQXl6?= =?utf-8?B?Mms0azRHM2hGV0luQk43cURHdnhBUXlaakpSM01QL1AzSXczb3NtNGdYSURI?= =?utf-8?B?dDIrYnVzRXdiWkJNWDhWK1UwSjZvMXVmZS9NRXBBaEFhckg5eTZBRWVmdVJi?= =?utf-8?B?cmMvMTVmdDdSQVc4M0l3cW9QaXhDeGVXZ3dpRWxGbkEzK3JmWnBqeTZ3eEl5?= =?utf-8?B?UmFRVDMxRUhSSWJvWTlibHhyTjlkQ0EyUWNyUUcyVDV0ZWFVSnJ2S2V3QmEz?= =?utf-8?B?ckhQajNiNkVBUlVYakhRNHVCeWFGRFFiU3doY1dtb3VFZlJCNWZMRmpoeHdS?= =?utf-8?B?Y3VxTC9kenk1b2xlSERjZkErVGdLSHFZUmZKV256cWNWcWZPWlFrak5OdlFv?= =?utf-8?B?NllrVFB6UVU3ZHJzT1lvZG9kRFVhb2hYYjg2bElXanRtMHFObWJBam1iL016?= =?utf-8?B?cktYOURSVGRYTGtzcU1HV0JsdVowRXMyc1I2TTNhK3pDVzY0L1NqSktWZURV?= =?utf-8?B?MGRySmluUjFLb3pnUko0aHNPYmlsOW01czdaNzRmcXdzSE8zeWd5VjIxaVRH?= =?utf-8?B?UlhVdjVJUkw1cVlWRG92WlFGemlGN0xXQzZ4b0R4Y3ZleVFJMkhnbnN1UEJz?= =?utf-8?B?OWMvV1pXN0cyK2h6VlRDZm9EUUprRHh6dkdWZExrOWxCVlF0UVlMYXdhSkpp?= =?utf-8?B?cHN1RUhINk1SS0kyTDd0bVlVK1NBZlFrZUxERG93OFVSZ2swQ25xbkJCdFRU?= =?utf-8?B?SUJGRVlNWjE2dEV2Z0FYejR6dzNnOFVKQ2hhMml6a0ZSeHNsNWNRb1JCRDNZ?= =?utf-8?B?OHN2SUpOUGxiMlhrZHY2dklacFI5REs1QUFEUXgyTm9vcGRkeWVMRkJiVkU5?= =?utf-8?B?ci95UjByUVZ0MkFTbldma3ordTM1eklYTHRyMjc2VjNNNDJvNkdEc0ZkYXBH?= =?utf-8?B?dWNHTHplWEdQVTY2UnM2VEtXMG8rREh4UW5wRWgwSXg0STBFVWlRUWx0Y09P?= =?utf-8?B?MjdhWi9kUUduK212SHE3c0h4VDRyTGtTTGdzRXNJR0dBdTRwMzVIODJOVmlq?= =?utf-8?B?M3lOc0p1UEFjV0JJUHpzZ1YxZ2RlUk44QWd2ZWxYREh5UlBkczRzWXA0d1Nw?= =?utf-8?Q?WRW44iI6PkeF9?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 674b2bbf-eb18-451b-44e5-08d8c9acd558 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB3775.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Feb 2021 08:05:42.8732 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: vbdRAz0bszEhKM6J5A8SwXAT3ZKejnozVxX8mn3G8AB1OSqRVrPShYh2McvwImBg X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4343 Subject: Re: [Intel-gfx] [PATCH] RFC: dma-buf: Require VM_SPECIAL vma for mmap X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Intel Graphics Development , Matthew Wilcox , "moderated list:DMA BUFFER SHARING FRAMEWORK" , John Stultz , DRI Development , Daniel Vetter , Suren Baghdasaryan , Sumit Semwal , "open list:DMA BUFFER SHARING FRAMEWORK" Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Am 04.02.21 um 19:38 schrieb Jason Gunthorpe: > On Thu, Feb 04, 2021 at 06:16:27PM +0100, Daniel Vetter wrote: >> On Thu, Feb 4, 2021 at 5:13 PM Jason Gunthorpe wrote: >>> On Wed, Feb 03, 2021 at 10:19:48PM +0100, Daniel Vetter wrote: >>>> tldr; DMA buffers aren't normal memory, expecting that you can use >>>> them like that (like calling get_user_pages works, or that they're >>>> accounting like any other normal memory) cannot be guaranteed. >>>> >>>> Since some userspace only runs on integrated devices, where all >>>> buffers are actually all resident system memory, there's a huge >>>> temptation to assume that a struct page is always present and useable >>>> like for any more pagecache backed mmap. This has the potential to >>>> result in a uapi nightmare. >>>> >>>> To stop this gap require that DMA buffer mmaps are VM_SPECIAL, which >>>> blocks get_user_pages and all the other struct page based >>>> infrastructure for everyone. In spirit this is the uapi counterpart to >>>> the kernel-internal CONFIG_DMABUF_DEBUG. >>> Fast gup needs the special flag set on the PTE as well.. Feels weird >>> to have a special VMA without also having special PTEs? >> There's kinda no convenient & cheap way to check for the pte_special >> flag. This here should at least catch accidental misuse, people >> building their own ptes we can't stop. Maybe we should exclude >> VM_MIXEDMAP to catch vm_insert_page in one of these. >> >> Hm looking at code I think we need to require VM_PFNMAP here to stop >> vm_insert_page. And looking at the various functions, that seems to be >> required (and I guess VM_IO is more for really funky architectures >> where io-space is somewhere else?). I guess I should check for >> VM_PFNMAP instead of VM_SPECIAL? > Well, you said the goal was to block GUP usage, that won't happen > without the PTE special flag, at least on x86 When is that special flag being set? > So, really, what you are saying is all dmabuf users should always use > vmf_insert_pfn_prot() or something similar - and never insert_page/etc? Exactly, yes. Christian. > It might make sense to check the vma flags in all the insert paths, eg > vm_insert_page() can't work with VMAs that should not have struct > pages in them (eg VM_SPECIAl, VM_PFNMAP, !VM_MIXEMAP if I understand > it right) > > At least as some VM debug option > > Jason _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx