Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 25 Mar 2021 09:01:03 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Thomas =?utf-8?B?SGVsbHN0csO2bSAoSW50ZWwp?= 
        <thomas_os@shipmail.org>
Cc:     Christian =?utf-8?B?S8O2bmln?= <christian.koenig@amd.com>,
        David Airlie <airlied@linux.ie>, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH 1/2] mm,drm/ttm: Block fast GUP to TTM huge pages
Message-ID: <20210325120103.GV2356281@nvidia.com>
References: <0b984f96-00fb-5410-bb16-02e12b2cc024@shipmail.org>
 <20210324163812.GJ2356281@nvidia.com>
 <08f19e80-d6cb-8858-0c5d-67d2e2723f72@amd.com>
 <730eb2ff-ba98-2393-6d42-61735e3c6b83@shipmail.org>
 <20210324231419.GR2356281@nvidia.com>
 <607ecbeb-e8a5-66e9-6fe2-9a8d22f12bc2@shipmail.org>
 <fb74efd9-55be-9a8d-95b0-6103e263aab8@amd.com>
 <15da5784-96ca-25e5-1485-3ce387ee6695@shipmail.org>
 <20210325113023.GT2356281@nvidia.com>
 <afad3159-9aa8-e052-3bef-d00dee1ba51e@shipmail.org>
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <afad3159-9aa8-e052-3bef-d00dee1ba51e@shipmail.org>
MIME-Version: 1.0
X-MS-Exchange-MessageSentRepresentingType: 1
Received: from mlx.ziepe.ca (206.223.160.26) by YT1PR01CA0073.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:2d::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3955.24 via Frontend Transport; Thu, 25 Mar 2021 12:01:05 +0000
Received: from jgg by mlx with local (Exim 4.94)        (envelope-from <jgg@nvidia.com>)        id 1lPOff-002VD3-KG; Thu, 25 Mar 2021 09:01:03 -0300
X-MS-PublicTrafficType: Email
X-MS-Office365-Filtering-Correlation-Id: fb51c72f-4372-4a84-eb23-08d8ef85ab45
X-MS-TrafficTypeDiagnostic: DM6PR12MB4137:
X-Microsoft-Antispam-PRVS: <DM6PR12MB413780DE27F1BE24A927AE32C2629@DM6PR12MB4137.namprd12.prod.outlook.com>
X-MS-Oob-TLC-OOBClassifiers: OLM:8882;
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:DM6PR12MB3834.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(376002)(136003)(396003)(39860400002)(366004)(346002)(66556008)(1076003)(66946007)(66476007)(2906002)(38100700001)(8676002)(26005)(9786002)(9746002)(5660300002)(4326008)(2616005)(36756003)(6916009)(54906003)(8936002)(33656002)(426003)(86362001)(316002)(478600001)(186003)(4744005)(14583001);DIR:OUT;SFP:1101;
X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?eER2ZjgwbG9vRC9TaWpicVNRWXhhWTY1ZjdDT1p0djFNZkZYL05PclB4K1Qz?=
 =?utf-8?B?V0l6emNCT09pQzh1cG9WYjlzanRQRUFiZUlGdzZkb1hST09HandXU21hbEh2?=
 =?utf-8?B?YmpWWlJweExBWGFhQTk0RTNFcFlhZUVwWE9MZjZBTWhCOVJ2S0VPbDBFR3lG?=
 =?utf-8?B?Q0I3YmxxQzQ3TEI3U05zbzdjZU9kL3gyNkdzNlRTL1U5TVVMdDVNOENYRzky?=
 =?utf-8?B?cW9yRlFvWFYrU1ZkdUM4SlpuTEdvOE5yNVVpekprN2oyYUp1WjdSL2oxaWZW?=
 =?utf-8?B?SXE0VFlGeFpzUDgvbDNaSzYxa2JiTms1NXc3NGd4ak43R0NVbHJyWHZhOTRF?=
 =?utf-8?B?K2VPbUQ3WC9vTVZnbTJtMk5xeWp5T01Zcm9xMFlubWE5UnFlVUtOUExUYVFw?=
 =?utf-8?B?czVTTXBMTDNuajVlcUtUUWJBbmd2SnBhNkNPbzRWMWhydjZMbWtORlhXZFRQ?=
 =?utf-8?B?LzhSdXoxajN2cGJCRklCZWxYY2xDUEU3NkE2OElHZnh1N05zN1A1V1QvdFda?=
 =?utf-8?B?UXdWdkNtZmN5ZEVQWGJJenBZWGdGM1lzVTVRNUdxSy9zUTV5TElyUlNET1hk?=
 =?utf-8?B?aDdxNkRSdW5BaUNMZFRRb1dqMEhYTTcxOHdyelpoZUp0NmxRaDJROS8wV1BZ?=
 =?utf-8?B?bzdQUjQ3ZTBrdERyYWpDNXFIeHVXOVZVSmhSQ2N4TFkyVDZUS0hZck83YzdL?=
 =?utf-8?B?ckhqdHRLZ2ZpclF2Z25TWFEycGdGbG4vYzFGUUdEWnlkNG8rZGtTYTBHOEZl?=
 =?utf-8?B?UHRldy9vWlJwdGhKNk1oMzF0bmc3M1BYZ2piZmNTMjVzUjZyR0I4YkVpU2NW?=
 =?utf-8?B?cC96ai8rWTNOYlF1RzZ2QXlJdEhPRHY2cmNtZ3VmZWZVWjZqUEgzdzhjUWxK?=
 =?utf-8?B?cWdvR1BMb0graFI1N1JWb3RxL3RSUzVvRXNoUmViY3BIVlRyZXhVN09oTENy?=
 =?utf-8?B?UmtuUlZBZnFkZ0dZem1BbjZOaTY3ejgwcnU2NGdZYS94TkpmSFhCcXdTek40?=
 =?utf-8?B?b1lCNDlTVnJZVWtpd2NpOFIzd05iUmNMb3A4ek03UzZpcEFjVjJ6akpic0hr?=
 =?utf-8?B?VS9USENpNUZBRVJFTDlVRUpDUTJjbjVBQlY2RFlFczd0WW5NY1RGT2FEVWlV?=
 =?utf-8?B?UlkzNHFaRVZzSjJSMkk1RURQTk9GVXE1S2FSMHArWXpiR0Zad3hmRFhjUHQ3?=
 =?utf-8?B?VVZpajcxQys3ZWU4NXdPNGRHQ2ZBNjNRZlM1MlFXd3pPOHdsbjJaQWtENWxQ?=
 =?utf-8?B?Z2NYcitCY01kQlZ6R25OaXQ3RG9IYlhsOGJMQ2FpbWtLb2o5RGJRS2NuYURk?=
 =?utf-8?B?b2YyL240L0JXL2VrTlI3UVRXQ3JidkdoQk1tQTBYM3crTHpYMC92cXNuVmR1?=
 =?utf-8?B?dHBQWGNlYU9KS3FSVm9pVHlOTXQ2VUo2aGF6Z0UrbXVESmtNekRjbFUvWjY3?=
 =?utf-8?B?SDFwbTVQR3RXcXZ2Ry9DTElUejEyV0hzL2RJcW9mK0xhaUczaEZKZU1lT0tL?=
 =?utf-8?B?aFFmSit3OWlnMnF3MHYrNjZhVFNxb25LK1Y5RUNETWV0ZUp1VTF1RUhPeVdl?=
 =?utf-8?B?Y2tHZDh1K2h0QmdLcEFPOTZ0cFZRS3IvVHFUU2p6enIzZlF1VjdEczZ4Z0pP?=
 =?utf-8?B?ZE1iZHUrUDdqYVlnLytvNkd1WE5va3ZBSWtpOGdJVnVlN3VFV1RMT2VoSmlZ?=
 =?utf-8?B?cElja0lzMDl5ejRadVVOd0ZBU1pqVTNFR1hGZndma2ZLcUdGakFKcE10OGVF?=
 =?utf-8?Q?HTrok8mZ9P905B98rmDYmo5qgKiX+J0dk7f0aA8?=
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: fb51c72f-4372-4a84-eb23-08d8ef85ab45
X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB3834.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Mar 2021 12:01:05.9258
 (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: aoweMP5MeVENl2JUqMlFVDfoy8ND6oUEJGODq+4RoBPbBWg/zkOG/IRwfCNQ1QWL
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4137
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Mar 25, 2021 at 12:53:15PM +0100, Thomas Hellström (Intel) wrote:

> Nope. The point here was that in this case, to make sure mmap uses the
> correct VA to give us a reasonable chance of alignement, the driver might
> need to be aware of and do trickery with the huge page-table-entry sizes
> anyway, although I think in most cases a standard helper for this can be
> supplied.

Of course the driver needs some way to influence the VA mmap uses,
gernally it should align to the natural page size of the device

Jason