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 69C09E77188 for ; Fri, 10 Jan 2025 21:08:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EF1CB6B00C1; Fri, 10 Jan 2025 16:08:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E79B76B00C2; Fri, 10 Jan 2025 16:08:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CCC146B00C3; Fri, 10 Jan 2025 16:08:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id A8F5C6B00C1 for ; Fri, 10 Jan 2025 16:08:17 -0500 (EST) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 2FE73C0E6E for ; Fri, 10 Jan 2025 21:08:17 +0000 (UTC) X-FDA: 82992780234.04.6275A7D Received: from NAM04-DM6-obe.outbound.protection.outlook.com (mail-dm6nam04on2046.outbound.protection.outlook.com [40.107.102.46]) by imf05.hostedemail.com (Postfix) with ESMTP id 4ABF4100007 for ; Fri, 10 Jan 2025 21:08:14 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=amd.com header.s=selector1 header.b=WAzRjjeS; spf=pass (imf05.hostedemail.com: domain of Michael.Day@amd.com designates 40.107.102.46 as permitted sender) smtp.mailfrom=Michael.Day@amd.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); dmarc=pass (policy=quarantine) header.from=amd.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1736543294; h=from:from:sender:reply-to: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=uSfg84KfS2/DuFe8JuJZo5twuYnNeLPGmVj+vl9Es2c=; b=yuO+GqAimNZ9uEIAJAWdh4THBwm7BO2F0M26Kep1DRPHkA50LyhdyPTgHg+NnB8YVgdsA8 mjCv1tqXaXHhkdeZlB6wHDgyhbll+Q1Z9lb0SO6BV2ekFi8yO8JvngkbqXS3fWkYEnE3Dp yFlpn3DptQDfPTzQQ7JqQAMiITfCtjU= ARC-Authentication-Results: i=2; imf05.hostedemail.com; dkim=pass header.d=amd.com header.s=selector1 header.b=WAzRjjeS; spf=pass (imf05.hostedemail.com: domain of Michael.Day@amd.com designates 40.107.102.46 as permitted sender) smtp.mailfrom=Michael.Day@amd.com; arc=pass ("microsoft.com:s=arcselector10001:i=1"); dmarc=pass (policy=quarantine) header.from=amd.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1736543294; a=rsa-sha256; cv=pass; b=q4Pfc/iaKFoovUvI7p1AzHM9MC1Z9sAlTjJXK36g4V5sObzzI3k5Cokve86vDVH9wrQmyx 63c2xRh4HQmoX2oZfx56zrurqoKI34tITgUTIswkvOyhVxME9iGwqoSQzn41u0bjkej9S+ qP2pyZkiW34q8y61jfXuXcEXE6r2RbA= ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=MDzx+a/fqoHgELri40DtecZb5+dUcjiCAo/r1wcxESp7IY9YWxgQUB8JjrRpttRqCDAEQmYXia/n+pxrVUQCcZx3JO9cIKx5BQ5jS6SmKp3s1ATCOn2PwnRFe+ETQHqxN6GzqFvYHk7nsRgdynBP8+1zIBMI0MyNEEhed0G41M6Qkv1fiyqKReDxNHM5AsAAlwbWvzyJomx/9nizXtlU9HKVbA8kp+UUAdFa3agrmgSVyxc4j+9TuPUm0iUEAmWgR7w4MWCdnIbgBNuBZ//30BuWzCNudWAYSUG4OOP5mx2DgQGr2BXzse6Y84cLLaALoGIG4L8cygimT+wuXeiA5g== 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=uSfg84KfS2/DuFe8JuJZo5twuYnNeLPGmVj+vl9Es2c=; b=YXzQBXWsJJ5X2toqZT3CoJHo6OWELaAlj9OhBha43EGoF5y6OQf9dG3gG2n9Qrt7RV1e8v4M2wzzZAJFvEkOSc/b+sto0K73IW9bAsvCnEDsl6ebJW0veSpKNh+3TyaTxK5uN+cPmbmoq7yRGZ1J9T/Ob+HjLdbexWkb7ywmeiwi9gHuj05iTzUmt4c0KTNdX3mA7rMoJ7eGl14Eqdgz2aWCl7GshH4d6HkcUJx8ExZipQZr3g2DlprUtPbrJOvO73lbs77mlhuMszk5LNi1XZq4EgNrGPlo+UF5HHP7N52QOe4+3hk4ulykGe+1Fu+2UoEf+gQnHcn+MYuKsE3KfQ== 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=uSfg84KfS2/DuFe8JuJZo5twuYnNeLPGmVj+vl9Es2c=; b=WAzRjjeS1kIAP0E5p16pH5QbLhJfbtxSYOlsW4z5lH6NyqDTB17LNvxRwmtF7Rp5lEVnOTtyugRvmCNJj57qLoCswGMM5Sh93BY4tZIrfFxMqnvm5vlmj2cXNpMvCxxN7A1ey/xa28F/GqWn5irkQgBZdSjxMqWyUX6/2YmNkuc= Received: from SA1PR12MB5672.namprd12.prod.outlook.com (2603:10b6:806:23c::5) by DM4PR12MB5963.namprd12.prod.outlook.com (2603:10b6:8:6a::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8335.10; Fri, 10 Jan 2025 21:08:12 +0000 Received: from SA1PR12MB5672.namprd12.prod.outlook.com ([fe80::60f:5e8d:f0da:4eca]) by SA1PR12MB5672.namprd12.prod.outlook.com ([fe80::60f:5e8d:f0da:4eca%4]) with mapi id 15.20.8335.010; Fri, 10 Jan 2025 21:08:12 +0000 Message-ID: <7cf9f0fd-279e-4e4d-99ac-966a752090a2@amd.com> Date: Fri, 10 Jan 2025 15:08:08 -0600 User-Agent: Mozilla Thunderbird Reply-To: michael.day@amd.com Subject: Re: [RFC PATCH 2/2] KVM: guest_memfd: use filemap_grab_folios in write To: Nikita Kalyazin , willy@infradead.org, pbonzini@redhat.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: david@redhat.com, jthoughton@google.com, michael.roth@amd.com, ackerleytng@google.com, graf@amazon.de, jgowans@amazon.com, roypat@amazon.co.uk, derekmn@amazon.com, nsaenz@amazon.es, xmarcalx@amazon.com References: <20250110154659.95464-1-kalyazin@amazon.com> <20250110154659.95464-3-kalyazin@amazon.com> From: Mike Day Content-Language: en-US In-Reply-To: <20250110154659.95464-3-kalyazin@amazon.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SA1P222CA0045.NAMP222.PROD.OUTLOOK.COM (2603:10b6:806:2d0::22) To SA1PR12MB5672.namprd12.prod.outlook.com (2603:10b6:806:23c::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA1PR12MB5672:EE_|DM4PR12MB5963:EE_ X-MS-Office365-Filtering-Correlation-Id: 4c2d9731-3f37-4fa6-fed3-08dd31bae431 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|1800799024|7416014|366016|7053199007; X-Microsoft-Antispam-Message-Info: =?utf-8?B?NUFyaGhMM0ZMMUNmS2drQjhJWW5MSGQ0WDZ6QitZS2NZUVVrL2tXbHYydEcy?= =?utf-8?B?bUZBS3JlRDZhbUtmay9TRWs5dk9TS29FMmVPZjE4UlJBV0gzQ3owdnRMaEQ4?= =?utf-8?B?ZHJydTlSQ2VacGJHclJQYnU2K2hVKzJwK29pMXlsUzFMbjJaUDMzTFk0WVkx?= =?utf-8?B?aG1NTlIveHRaVEh0dDV3ODJzQm5lYUI2eEt6OEQzSVA4QUUwQVcrblREYVpl?= =?utf-8?B?T1g3Q1dPTWxCVmlKT3VIYXV0OEI3em9zd242TXR4aTg4bGpXaGFDWFFaaUVu?= =?utf-8?B?WFpYWFY0VUVhUDZ6cUgrckJWYXZUZzYzRS9OdnRzTGl0YVlMT0FFcjlPd3dB?= =?utf-8?B?a3B4K1RrMjB2K0JPSjM5ZnZNTkNSemNhUnNTb2w4b0JkdXAzak1RWHZjdTVj?= =?utf-8?B?RHZtYXZNT21teXZPZ0ZjVnc0MHM3WE01SUxnRUhLYkJndE9zRHJVTmlGT05N?= =?utf-8?B?QUxOMVRndVJaUXJLaHNUNXNpbkgxWUp6T0ZkM3J3VUtnL29MZ1JTS05xMktj?= =?utf-8?B?M1dWMDdpdUtEaE9hT1Y1d2FtZlUwbVV1ODdoTjNHT0N1Wkk2V1haWjFocWRZ?= =?utf-8?B?UnFnYzdYUGRkVG5qLzBiZ0Z2dHEzU21hMEpNbEdXMXdqNXh3dHZ0c1dQTGs1?= =?utf-8?B?eHdkaS83TkNjUklyYVdnTnRsTTBkaE9MNEk2d3JXUXVQdUF1RmJmZjRWcmd4?= =?utf-8?B?Z0VnNFE2a3V6YzdXNkxpeUo3RExERUZRSHRmUVdwdXlmZkFZWWlBZ2NhdXZZ?= =?utf-8?B?cTVmYlEveUEwcG1YV0pkZHc0d0lya3BzVXMra3dDZ3NZL1M2N2g4Mno4elUy?= =?utf-8?B?N3JPZklqYWF2em9NZWRjL2pNNzVDWXlBRnZZWWcrYlloeCtEbTk4a1ZoVGhI?= =?utf-8?B?RFZaK0UrUnlPQ1hnem1nWS9zVlAwd2t4a09Vb1RVK2Q4aGtFSEx6aDExTjFH?= =?utf-8?B?SlNNWEtQM3Q0RjFjd21DSGIweld0Q1Nsek40cjdURGNGejc0UDNaMXNYK1ZT?= =?utf-8?B?cFRVRklscUtCTi9JVzJNV05uRGxtUCtTR0VuMlNLVWRod0k0Wk4yb1poK2VO?= =?utf-8?B?OW96OWlUZkZPRFVaYUEyYjJlai9OTTZuREJZNnRzYXgxTk5McU9kbDR0YllK?= =?utf-8?B?RERzSjczK2lhdDU5dEtFaDl1aU0zRmN3dDJKUHljU2o4TnZPV1F3K3ZVSS80?= =?utf-8?B?ajB0Rmc0b28zcWo0SldkT1p6Slc5SkZZUUsvMkdxVUNvNDZRRXhTOXIvd2xu?= =?utf-8?B?cG42cUtJUFUwUFBKakFBakE5QUdGcy9RQ3puc1BHeGZIamVxcFNHZFZ4SkNr?= =?utf-8?B?OEl2NTVlc2FMVnlRM1VxbGlNSWFHOTBWY29yZUU1eXduNGdmWnBPa1VBZkxC?= =?utf-8?B?L0NOQmhQTXpObEM2Y0dxWnVCYTRxbCtUMDRmOTVSR3V5NzI2NWRWRmdXWFFM?= =?utf-8?B?YWM4enFBajhjQ29kSmIrS0dnL3NhOUMwald5Q0tublUxMXNpSDJKU0p3RmJu?= =?utf-8?B?SGZ4U25iODdqTW9QSDlkNWRNZ0QzRXZtTmhldTZoZ0kvVC9aS1FHR2tCVnJZ?= =?utf-8?B?UDVLVTYxNkhQeUhFZFBtMklUK3dtaVFVSytwek1VZ2tYTndVZDU5YUhKb051?= =?utf-8?B?T2VvenRWTUYwNGJDeFF1S1ZiUFkxWVlLQllHbEN3b3E5cHZJNk4xSjVpT2Jo?= =?utf-8?B?WHdoSGdNQThJSWg3ekdKWkw1S096TzQwQUcrbVlwWEZpQnpMRUhmb2xHKzB3?= =?utf-8?B?NDRsTE5UbVlVdE04bldaa3R1WEVjbkNJUUZ5L28waEVkcWZGb1AvRTg0eU14?= =?utf-8?B?RzBDejJOcTRsZGV5cE5lY2dEa25UYWlLNXcrSmxTNUc1a1pqZXkxWHRXVllK?= =?utf-8?Q?0YVSSIfDUdqHe?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SA1PR12MB5672.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(1800799024)(7416014)(366016)(7053199007);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?UVoxck1lbWx1NVdhOTg0VTU0UGU1cnVBeVdTUDFFUUxBL1VRZVloK1Q5MUhu?= =?utf-8?B?VzZTQlZZRUxvc0lVcEVrdUZXbW9vY1hqK2lXazZ5L0VaVzdaY3BIS2VYUGZn?= =?utf-8?B?Y0xvSi9od2NVQmUvT3VJVXVzelEvYWszVHJiS1h5RmJrYlZRZFJvbitNS0ow?= =?utf-8?B?OTBmcGZzaHFFNi82cmV4czhmYmVkdlVidHR2enpBajlYa2xjLzdTbUFsUUJ3?= =?utf-8?B?YXJTTXRoVjZLbFd3SUhrbGlTeXFydDF6ei8raHlJU2NDaERnMHBla0pwV0Zx?= =?utf-8?B?K1pQWTFEbGp2K0I5YXNnSXNnTUU0Ym9SZWZPYlNQY0FldCs0eEpJMytVUWV0?= =?utf-8?B?UzN4MmhRMWxaRWNtNk9RSGZyZEZqeDgzWlU1V0ZIc3h0ZkpOQlBwT3NZVWZJ?= =?utf-8?B?WHFJMVV3QkdKaW9vT1pwWWkrV2JKQUNxc0N1UDdUVS9HUlMvS3A1TEF6TUxO?= =?utf-8?B?ZFAvV25JclcraHRrb3dZUWxVakNmVXFEaVNNbWw4UEwvTit5dms2dmRwRlFF?= =?utf-8?B?RGxGaktkWGlRNld0WXVmSFJKWWZKakdybFBod3NET0Z4Sjgwb3c1Z3R6Njdl?= =?utf-8?B?NXNGNUZac0Y2b2t0OWMrMTR1NmpWWWQwemlFelA4S1gxcEM0azlsM28rNlA2?= =?utf-8?B?ck8rS2ZOU241TXh6WEkyT0I3d3dzamZDcElnUFdvY0ZCSDVUTEZFY0Q0MGlI?= =?utf-8?B?U1R2NHlLZFQvN1FHQXE5RDY0RUFUUmZ6bVByU21zY2lrRFZVS1I4UFpCNGpT?= =?utf-8?B?SmoxTXBqTmdYaitWTEJPeU9ocmhVVmw3UEM4eHlXZXQycVlFQzNLSFQwanY4?= =?utf-8?B?L2JrMlJwdHlhOS9aRGZobEhTdHF1dHRVWngzSGxBQjJudlRIanZUdzdXdDhz?= =?utf-8?B?WHExYTBSdDZMRlI2d1lCcWJSaU9tZWZMSGlUOFpGQVhiRC9wK1lCSDRrcTV6?= =?utf-8?B?VmxqMklnZi9OQmxkY1k4ZjdCNU5FaGJJQVpwblBhc2tuQnlTbldxZ0Y5VWRW?= =?utf-8?B?dUNORXZCYVBZMTVaeHNZTFgrWE5lbHlCenMrdUc1c0dXbVFNTUVFeDFVdytW?= =?utf-8?B?eUtzaHozNThQcGc0WkVKb2NjS2F5bE5UUWcxT2lVNmlMYzMybERTWGZjaGEy?= =?utf-8?B?WFZaZ2tvTVgyYmpVUithVmxHQVk1VWtBV3h2Y3NVakJ2K1JsMmtnSktmMXRR?= =?utf-8?B?aUp4U0c4UGtOL1NoNUZFcXF0UU03YzFMWDdUOW13V0VmRm5TUnF1UUV5dGlN?= =?utf-8?B?ejJKa3pmdTBPOVduS3llTGNTYlUxb0l4TzVYbEYyWVYzQ01XdUNQLytVWGg2?= =?utf-8?B?aENxOGNTbTVQdkFWN3RoNGNiNk1ua0U1enhoN1lUbCtLd0NXSW4xUytLWWdm?= =?utf-8?B?cXMrUE93WUZPd29zR3JWRUFDN29Mb2hpYUFyTVZpZWJFM0FWdmFkbFdlUkoz?= =?utf-8?B?UG9aKzFoUVM1NHozTEdoaTRlMU1NdkdqQzR2Y3oxMlZWVzZKcjdlejlQZnM3?= =?utf-8?B?VzBodjBsa0lhQWZGMTQ4V2hTQXgvZkdJTHJna2pWK0o2WmhkTXBGRmsrMExq?= =?utf-8?B?cEJINnc4cGRCMnlIdjdlZGtGRXNaOWluYWVPUkUzQW02OUdYUGVrL1N6ajZy?= =?utf-8?B?VmMrS2tIZ043TzNzR2dVNEVsRjhYcHJGTDVsMGIrVFVXZnlIdHZDTUJBQzZk?= =?utf-8?B?WStWaDJNaGQrcGRqS1AwTGNrMWlyU2pQaHpEOTVDaFNSY0lDSzhsako4UHgx?= =?utf-8?B?a3psWjFYOEQ3YlZveVArbW5NK0YzVURHNHd1Qlg1UDhvd29PSDB3S3lZNzdq?= =?utf-8?B?MnJxUjAzeXRTZmxkY0hlSUVYcE5QZ24xeGFNaFFZUkpuNkgyaW5pZmdSTGk3?= =?utf-8?B?T3ROUDhNZGFOMGt4RU9haVJ6SFo3Sm84Szd4d3crYXRCZzI0R1RHNkVjcmoz?= =?utf-8?B?L2I1Y2VOWEN5ejhOcWdQSHF5OEhxU203eFhFZzJtYk1aL3VtZGk0Zitzc291?= =?utf-8?B?QXlUaUFIME4zZHMvMU4zRmh0RmNNdEtpREpqY1dIRUVXS21VVUVMcG9jbWVG?= =?utf-8?B?VmFCSXVpZ0ZxUjVRalhINmMxaXQ4eFV6RmJHaXY2WHBTTU5ZSzU3S2VEWVQ4?= =?utf-8?Q?/FtOmlTRqm8wS7skVfiBmfRxF?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 4c2d9731-3f37-4fa6-fed3-08dd31bae431 X-MS-Exchange-CrossTenant-AuthSource: SA1PR12MB5672.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Jan 2025 21:08:11.9798 (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: UWyiRRRN7VRGr8g52A2dguFz3mb9QmRYHem129aFpJZRKh7HFlnv9QK27ys6/IXEvcx+4DwB4OeakPSkgnTBlw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB5963 X-Rspamd-Queue-Id: 4ABF4100007 X-Rspamd-Server: rspam12 X-Stat-Signature: z98gtdetbos8nauadjcwzd6ocosix3qx X-Rspam-User: X-HE-Tag: 1736543294-429165 X-HE-Meta: U2FsdGVkX18PCSHl2zI4bmnc+dJ90uAOzbNGA4vib4XqM9zNr+M7vn5bjl4bPQ5wnbJGQzWVKhmFBEa63qXPEZsnprS0h/BF6UbM28Q2SxMNXUdEAaCLO8k4UriPPcX4G0BIwR8S6N2qDGsMQ7X3Ky6wvslGLjGeLy8lvKJ/ASpfeCk9Mg0SCoR4sUJq8y707LO4g16bb5yYINkHVxTGGdFc7K0OkGSmZUVxuaQ+3XViJp/4IDPDotldw05xzzfoUc3+S0xIeYaxUrZmXjdZO9CCoIiP4wNtPgaKJQykYCS5RjiRUtGmJQl5wTNbn2UsQxTsDLzzA9HuPi9Y6BQ/Gn/4KPdzfuo/eVepHVbWaFdgMsS27as9qV49nronsFRWf8pEGKeFU3rG11o/QsQlInyEQWWi6qBxJp+BQ3HwsHArWzdT7tunBPW/FzdhgZzgWwhs4tXOanGd1qMKRPo6cW8JQ0db73dzrllRrBm5N8JVaUq5YDfj7Mk9w030PSrxj9FPpCJmCrcirXpA9DnBmk35m1F2KvbIyuonZB8cq1BypSu7evrwNqXolrSNXPYj1r4rQb8NUuaANjkrnq2EYYi4JxOakDNJthq6+Xedqp8PARw3P3m/mE1SWTKflI3a84z6sleaNgQPTWcvVcIwTiiaV0KnC3bUKKHQ7vgdB8MgNNOVhETyIgPHDb6oEEyc9bJH6KBruWEcGPxEv5gujgYYNxcWnpJ3I/X6cvCOd+79U+HghZ6Q0IQa6VoJabrJFmvOEl8yrtd1bwTvsYYKFxjx4JTqehY8/061JqK8Y+/k9FgL+jFwKKd2vHxuuU1Xh2fxLzQE2VNWJRy2bQ/Qj59+/2r7IMZI+8eXbncOKWsERrSJ4r/a5bAbZHUBIqX93Ke2BalHISC4wAYsBjdEKXLzPisvKFfU6thKlzGtNcMFFm3fEi9aXivsXykfkCDp4jd1Wu5j5K3HyieuEc8 kyR4CKBV 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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 1/10/25 09:46, Nikita Kalyazin wrote: > The write syscall on guest_memfd makes use of filemap_grab_folios to > grab folios in batches. This speeds up population by 8.3% due to the > reduction in locking and tree walking when adding folios to the > pagecache. > > Signed-off-by: Nikita Kalyazin > --- > virt/kvm/guest_memfd.c | 176 +++++++++++++++++++++++++++++++++-------- > 1 file changed, 143 insertions(+), 33 deletions(-) > > diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c > index e80566ef56e9..ccfadc3a7389 100644 > --- a/virt/kvm/guest_memfd.c > +++ b/virt/kvm/guest_memfd.c > @@ -102,17 +102,134 @@ static struct folio *kvm_gmem_get_folio(struct inode *inode, pgoff_t index) > return filemap_grab_folio(inode->i_mapping, index); > } > > +/* > + * Returns locked folios on success. The caller is responsible for > + * setting the up-to-date flag before the memory is mapped into the guest. > + * There is no backing storage for the memory, so the folios will remain > + * up-to-date until they're removed. > + * > + * Ignore accessed, referenced, and dirty flags. The memory is > + * unevictable and there is no storage to write back to. > + */ > +static int kvm_gmem_get_folios(struct inode *inode, pgoff_t index, > + struct folio **folios, int num) > +{ > + return filemap_grab_folios(inode->i_mapping, index, folios, num); > +} > + > #if defined(CONFIG_KVM_GENERIC_PRIVATE_MEM) && !defined(CONFIG_KVM_AMD_SEV) > +static int kvm_kmem_gmem_write_inner(struct inode *inode, pgoff_t index, > + const void __user *buf, > + struct folio **folios, int num) > +{ > + int ret, i, num_grabbed, num_written; > + > + num_grabbed = kvm_gmem_get_folios(inode, index, folios, num); > + if (num_grabbed < 0) > + return num_grabbed; > + > + for (i = 0; i < num_grabbed; i++) { > + struct folio *folio = folios[i]; > + void *vaddr; > + > + if (folio_test_hwpoison(folio)) { > + folio_unlock(folio); > + folio_put(folio); > + ret = -EFAULT; > + break; > + } > + > + if (folio_test_uptodate(folio)) { > + folio_unlock(folio); > + folio_put(folio); > + ret = -ENOSPC; > + break; > + } > + > + folio_unlock(folio); > + > + vaddr = kmap_local_folio(folio, 0); > + ret = copy_from_user(vaddr, buf + (i << PAGE_SHIFT), PAGE_SIZE); > + if (ret) > + ret = -EINVAL; > + kunmap_local(vaddr); > + > + if (ret) { > + folio_put(folio); > + break; > + } else { > + kvm_gmem_mark_prepared(folio); > + folio_put(folio); > + } > + } > + > + num_written = i; > + > + for (i = num_written; i < num_grabbed; i++) { > + folio_unlock(folios[i]); > + folio_put(folios[i]); > + } > + > + return num_written ?: ret; > +} > + > +static struct folio *kvm_kmem_gmem_write_folio(struct inode *inode, pgoff_t index, > + const char __user *buf) > This could probably be rewritten as: struct folio *p_folio; int ret; ret = kvm_kmem_gmem_write_inner(inode, index, buf, &p_folio, 1); if (ret == 1) return p_folio; else return ERR_PTR(ret); Would remove a few lines of duplicated code and use only one prototype. Mike +{ > + struct folio *folio; > + void *vaddr; > + int ret = 0; > + > + folio = kvm_gmem_get_folio(inode, index); > + if (IS_ERR(folio)) > + return ERR_PTR(-EFAULT); > + > + if (folio_test_hwpoison(folio)) { > + ret = -EFAULT; > + goto out_unlock_put; > + } > + > + if (folio_test_uptodate(folio)) { > + ret = -ENOSPC; > + goto out_unlock_put; > + } > + > + folio_unlock(folio); > + > + vaddr = kmap_local_folio(folio, 0); > + ret = copy_from_user(vaddr, buf, PAGE_SIZE); > + if (ret) > + ret = -EINVAL; > + kunmap_local(vaddr); > + > + if (ret) { > + folio_put(folio); > + kvm_gmem_mark_prepared(folio); > + goto out_err; > + } > + > + folio_put(folio); > + > + return folio; > + > +out_unlock_put: > + folio_unlock(folio); > + folio_put(folio); > +out_err: > + return ERR_PTR(ret); > +} > + > static ssize_t kvm_kmem_gmem_write(struct file *file, const char __user *buf, > size_t count, loff_t *offset) > { > + struct inode *inode = file_inode(file); > + int ret = 0, batch_size = FILEMAP_GET_FOLIOS_BATCH_SIZE; > pgoff_t start, end, index; > - ssize_t ret = 0; > > if (!PAGE_ALIGNED(*offset) || !PAGE_ALIGNED(count)) > return -EINVAL; > > - if (*offset + count > i_size_read(file_inode(file))) > + if (*offset + count > i_size_read(inode)) > return -EINVAL; > > if (!buf) > @@ -123,9 +240,8 @@ static ssize_t kvm_kmem_gmem_write(struct file *file, const char __user *buf, > > filemap_invalidate_lock(file->f_mapping); > > - for (index = start; index < end; ) { > - struct folio *folio; > - void *vaddr; > + for (index = start; index + batch_size - 1 < end; ) { > + struct folio *folios[FILEMAP_GET_FOLIOS_BATCH_SIZE] = { NULL }; > pgoff_t buf_offset = (index - start) << PAGE_SHIFT; > > if (signal_pending(current)) { > @@ -133,46 +249,40 @@ static ssize_t kvm_kmem_gmem_write(struct file *file, const char __user *buf, > goto out; > } > > - folio = kvm_gmem_get_folio(file_inode(file), index); > - if (IS_ERR(folio)) { > - ret = -EFAULT; > + ret = kvm_kmem_gmem_write_inner(inode, index, buf + buf_offset, folios, batch_size); > + if (ret < 0) > goto out; > - } > > - if (folio_test_hwpoison(folio)) { > - folio_unlock(folio); > - folio_put(folio); > - ret = -EFAULT; > + index += ret; > + if (ret < batch_size) > + break; > + } > + > + for (; index < end; index++) { > + struct folio *folio; > + pgoff_t buf_offset = (index - start) << PAGE_SHIFT; > + > + if (signal_pending(current)) { > + ret = -EINTR; > goto out; > } > > - if (folio_test_uptodate(folio)) { > - folio_unlock(folio); > - folio_put(folio); > - ret = -ENOSPC; > + folio = kvm_kmem_gmem_write_folio(inode, index, > + buf + buf_offset); > + if (IS_ERR(folio)) { > + ret = PTR_ERR(folio); > goto out; > } > - > - folio_unlock(folio); > - > - vaddr = kmap_local_folio(folio, 0); > - ret = copy_from_user(vaddr, buf + buf_offset, PAGE_SIZE); > - if (ret) > - ret = -EINVAL; > - kunmap_local(vaddr); > - > - kvm_gmem_mark_prepared(folio); > - folio_put(folio); > - > - index = folio_next_index(folio); > - *offset += PAGE_SIZE; > } > > out: > filemap_invalidate_unlock(file->f_mapping); > + if (index > start) { > + *offset += (index - start) << PAGE_SHIFT; > + return (index - start) << PAGE_SHIFT; > + } > > - return ret && start == (*offset >> PAGE_SHIFT) ? > - ret : *offset - (start << PAGE_SHIFT); > + return ret; > } > #endif >