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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 58623EA795F for ; Thu, 5 Feb 2026 03:50:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9FE7D6B0092; Wed, 4 Feb 2026 22:50:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9A8A56B0093; Wed, 4 Feb 2026 22:50:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 869EA6B0096; Wed, 4 Feb 2026 22:50:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 72BE16B0092 for ; Wed, 4 Feb 2026 22:50:10 -0500 (EST) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 283E88B6F0 for ; Thu, 5 Feb 2026 03:50:10 +0000 (UTC) X-FDA: 84409024980.13.BADC869 Received: from SN4PR0501CU005.outbound.protection.outlook.com (mail-southcentralusazon11011003.outbound.protection.outlook.com [40.93.194.3]) by imf09.hostedemail.com (Postfix) with ESMTP id 2418E140004 for ; Thu, 5 Feb 2026 03:50:06 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=amd.com header.s=selector1 header.b=m3ecdhPP; spf=pass (imf09.hostedemail.com: domain of PratikRajesh.Sampat@amd.com designates 40.93.194.3 as permitted sender) smtp.mailfrom=PratikRajesh.Sampat@amd.com; dmarc=pass (policy=quarantine) header.from=amd.com; arc=pass ("microsoft.com:s=arcselector10001:i=1") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770263407; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=OUz/5TzpnJljMSykwz3l06Nrmi4GdzByT7RobYsbT2M=; b=YGMBpv5yLD4vhQ3RkDoG4WHJdSDHYqYmW0S3eNXuDuuCXZFrjYezPS0E9yo6c/iEWs1d1+ hZQxBG8OHWPLtk6MLvz++crp3x92uPV9M+6jnEEidJ5AGFfxb0WWMZbWwz3GwZkX3ZewFz xmk/gaSIhiB9ukiAlA3q/TFf6ZyVv4g= ARC-Authentication-Results: i=2; imf09.hostedemail.com; dkim=pass header.d=amd.com header.s=selector1 header.b=m3ecdhPP; spf=pass (imf09.hostedemail.com: domain of PratikRajesh.Sampat@amd.com designates 40.93.194.3 as permitted sender) smtp.mailfrom=PratikRajesh.Sampat@amd.com; dmarc=pass (policy=quarantine) header.from=amd.com; arc=pass ("microsoft.com:s=arcselector10001:i=1") ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1770263407; a=rsa-sha256; cv=pass; b=3hyS10eSDyMJ9F38aUz65MSml8EukRAhcBZvKpdpnLQSTm/Uiek83lY/RtK0fmaOuINFO0 u6/Kk02eAvPsazItGA+EJGxtYj8ocXwlHty2cKa7kzJtL6r/XTSY3bfZ28Oym9MM6RTTfD xln4zPsgvKW7nOzfgQLBbClfW1OcSTw= ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=bJtvs1CbShigO+/u60QvgWrKT2b0lT1J22VrfjVgHjSL7jhar3xmh/1X2ZQ5njip4zIydM5WqoBd+9CJglK0k1yRTVshoz4eJqCrYkHCqXQefuKiwDra4zyUjuAH6PcjENcS3HokhoqYQKeTCi56Nh7ZeJBgYY8Ffu9A5aXfuMFx8+pWU/kp6l/fgInB6gB+szLR8H6g+GG/LYHcvqjgp0ht1vYnw9hUPcQe/koC0D0g4cTnaEVRGwATUxYqDU2M+CHu3QPyQpapF89Pg+7kaDj5hZBqbKzKJJqfJJpyIdpXp1jxi35aWg3nCX1+4OSdh/pEIAaR+fxaMStkYqE3Ig== 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=OUz/5TzpnJljMSykwz3l06Nrmi4GdzByT7RobYsbT2M=; b=ujqrngMNXfY6PZLExU2KigPqwDXZOYJtJbeUZmQLK7CyMjGB8UHD7BS88fyRMJe0ZnLuWIX/ljIamXwcS5rIpS3Asw7k3G3SO9Eb9fG/WxseV36Qsp3YeR4vKHOo9FoeXv5tGUDQt97LeXF1j5K2bRg3ybbv6610VWXzrKrOgs+yA8DRFfa1/kmqfEEU1bcf0F3YuMsqCpV92/ejgsGdMJBajY0WMhbf/8L64n9hQYZ17jgXybUb0NCypRgQWo+j3AEZxNCBcsrdSk0TkustyWtOkaqr8fhJjuJ4M59ncDAk1Gb09b83A36ezPF1cyRBPH1d8FN0zQpZQ/vm80FhEA== 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=OUz/5TzpnJljMSykwz3l06Nrmi4GdzByT7RobYsbT2M=; b=m3ecdhPPXqFnUQsKFRoMC5LjY68ALN5/jcwCfuq7pbb03KnWIievsJnN2ndUCV7/kduONYnI43sZEnC87UjSkcJ1Oa+auuemNvLBSjgSsh1yrfv1nMv+MpzrU9ohKcpTJJOUVAzW7nlTmCrx1MaawgeJmJS+SVbz1kYRxzdIROY= Received: from CH3PR12MB8660.namprd12.prod.outlook.com (2603:10b6:610:177::5) by SJ2PR12MB8977.namprd12.prod.outlook.com (2603:10b6:a03:539::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9587.14; Thu, 5 Feb 2026 03:50:03 +0000 Received: from CH3PR12MB8660.namprd12.prod.outlook.com ([fe80::87aa:52e5:4b72:d5f3]) by CH3PR12MB8660.namprd12.prod.outlook.com ([fe80::87aa:52e5:4b72:d5f3%6]) with mapi id 15.20.9564.016; Thu, 5 Feb 2026 03:50:03 +0000 Message-ID: <550c89ae-de6e-45f7-89a2-ccc815f8d5a2@amd.com> Date: Wed, 4 Feb 2026 21:50:01 -0600 User-Agent: Mozilla Thunderbird From: "Pratik R. Sampat" Subject: Re: [PATCH v4 1/2] mm/memory_hotplug: Add support to accept memory during hot-add To: "David Hildenbrand (arm)" , Kiryl Shutsemau Cc: linux-mm@kvack.org, linux-coco@lists.linux.dev, x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, ardb@kernel.org, akpm@linux-foundation.org, osalvador@suse.de, thomas.lendacky@amd.com, michael.roth@amd.com References: <20260203174946.1198053-1-prsampat@amd.com> <20260203174946.1198053-2-prsampat@amd.com> <29b4dc97-bb01-42fd-8ccd-f4cb2886ccd3@kernel.org> Content-Language: en-US In-Reply-To: <29b4dc97-bb01-42fd-8ccd-f4cb2886ccd3@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: SA9PR03CA0023.namprd03.prod.outlook.com (2603:10b6:806:20::28) To CH3PR12MB8660.namprd12.prod.outlook.com (2603:10b6:610:177::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR12MB8660:EE_|SJ2PR12MB8977:EE_ X-MS-Office365-Filtering-Correlation-Id: d8b4abdb-bbdc-41f2-e857-08de6469a506 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|366016; X-Microsoft-Antispam-Message-Info: =?utf-8?B?ejI5NUV6Z0dXKzZvK1AzRk1MSGpGb0RFK1UxeWdMbDh5MEJCL1JTMTRTcUgy?= =?utf-8?B?a3lUWlZ3ZFJMajRhallKME5Xak05NnJ1UThpeksxMlJOOFVtZCtqTDQ0UE5h?= =?utf-8?B?MGZvd3ExaGx3M3FWUU9vZnBvY1gxZjMxVDhWWjBkcFlOYXNiOTBQeGpYcjNp?= =?utf-8?B?SWVuZzc3cE9uQlo5L3NLTURQQzMxdkx6Lzd1em5UMmEzOGVQQ3VVY1NMSmdT?= =?utf-8?B?NG16Qjl4Nk5RbkhvVG5mOExWVVRwQUxaQWZuZTlabTJRVlhoMkRDUEsySFVW?= =?utf-8?B?SGxjOHZpQ3NOdEdnZVZQNXpHSm9NUUlqRTNxN2pVWVVXeEx5YnFGUmFxSmxx?= =?utf-8?B?Qk1rZVQ3K1h6QmlVUDN5d3VJck5wZy9RSkZwc2szSVZwLzU4aEpDZVZBU3Ix?= =?utf-8?B?MHd3MVB6Sk9WY01uNG5mVE1uUllaRTZiSGRqYlFYWEtTUUVialNaSGFobWFo?= =?utf-8?B?Nld5L0NuTEdxS0VLSllZbTBJNW9FVndOTmpuSElTdkFPNnlFb3VSejI1WWdY?= =?utf-8?B?TlhIRFBUalh3WFQ5S2ZySXVlZWg5ZDUxV0J5SFVRekpndFVlL3hVZ3JHQnVi?= =?utf-8?B?SjNBQS9BL3FEWU83ZUliM1h3UVp0SThpRDZheTF1eDgxM28vVFU0SmJ2bUxZ?= =?utf-8?B?dDI3U2UxZWxPaWljTXkzdERWMXRWaS9SWFNFY0hmNGJteW04cW05QnhnOU9a?= =?utf-8?B?RGhWcU9Jb3YrTTJNeG9hTjB2STNvT1pvV0JxNzU4enVBT3VIUW5qcjJxM0xs?= =?utf-8?B?bDgvM1ZEM3Z5dGRCdTZ1VGFNbXF4aVJheUdGRUhSZGo1TlFWdWNBN0N3QTJy?= =?utf-8?B?Rk1SNW1Nd08zdllTR1NZdTMrQXBMRGFld0Y2cmJBUWFKOURrcWZyRStNMGF5?= =?utf-8?B?S3lDSUFNcmh4bGZNbHNHb3ZSYzZjNCtKYm14dHBTMStJT3ZpQjZiTWFuVm1v?= =?utf-8?B?RDhFWGp0ZGJ3YkVsRVB0bm1MYTY5dFdZZ3pPQWx6SlRuQ2ZDZG1maFd3YWlw?= =?utf-8?B?TTA4eWM4SnZaejRvSjBvaW9DNTd2V21vQmdiSFowODdkR3lKZGNGN0ZLcHo5?= =?utf-8?B?WkJxTUFqU3FLWU1wUU1naG5KeGhSUWZYWkZGYXNRY20vUlBEbGRKTW5lMGQx?= =?utf-8?B?dEc4cEoxUWk2RWtnRWl1R3hPRVNBWUorcnpCdmNpV1Rsdkg3emJoOG5qeDRC?= =?utf-8?B?NEp3ZDF2WFJmWDNIZ0NoVkxBUUpQYjNLMUJHZEZFS05pRTl5STU4RnJSYW0v?= =?utf-8?B?amVJQ0c5SzFWK083UVIyeFlPVlhXdGF4ZEphaWd1ZHBxTGNOY3k0STJEWFNo?= =?utf-8?B?T2kwRnRCZTJRR045T1ZGbFpRMnkwdFJpcE9NazBqWTdZeXBLdHRIY1hiK2Qr?= =?utf-8?B?czlUZUhIZGJpVThBMjBWalF5L2dqdlQ2bGhoWXc0K0xUTXdObDV6ci9WeXBz?= =?utf-8?B?QVM2cXhnay9yMHhmVXp3MEdDM1JMczhqMGpYWnZDdlVGUlBpY296R2lZUTNw?= =?utf-8?B?azQ3cjE1SUF6dTJlbm5tcCtFVXJudHo1QUlPb0w4SlhHYnhHc09TTCt3OExS?= =?utf-8?B?OWllaWhjakIxMzg4c2Z3ZGtlYzhRU0lFR01RcDR5eFgzaE9tRWVRSFVpQkhI?= =?utf-8?B?d2NValZiTzlLK09tMHNEVEtYY1N6U0NlNmhOMlh5TEwxRzBXM0lSTWU3UVd0?= =?utf-8?B?dnpRVW9YVUZvUDBEUzRLT1lEQW9COHF5VSsxeDFGb3VjUXc0SVlJYXBiakhz?= =?utf-8?B?VFFnTGFPMUNiMm5oTkNWQWpqMFVCRDJIT2l3RmFjUExiYm52bEpOWUNYVmt4?= =?utf-8?B?TXRYV2JuVjMrRXU0SFlwNFJZbEJXMmVaa3IxR2dHZHVOVTcxUks1VEF2WXJ2?= =?utf-8?B?cHUxSlc4M29UUVUrT2JkQzBMb2pLSVZwVmErT0huMVN0YmZYMWl0OHVLYVVH?= =?utf-8?B?ZnNMeDZDb2hqRGpWOGNYYjB3V2Z4elRhbnRMRWQvcWhXWWRiRzUrd0Z2cmtz?= =?utf-8?B?T1VlNkordGZUOFhBNWV3d0NwTndWMlp5OVMrQURIKzBYd0ZDc08vY1F3cWlU?= =?utf-8?B?Wks4UWtnTXRjMnBiWFRQc0hva3QrOVVDNGRtV0lTR0hmVHpsajU5Z2k4UVVL?= =?utf-8?Q?RG1I=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH3PR12MB8660.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(7416014)(376014)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?RDVWellBeVE5TlB2cllPVUZIbmJGc2Y1NkFJM3lvUFA4SnVrMlNHdEM0NE5r?= =?utf-8?B?bzFUbXVGbGh0OW1YMFAxa0FvYUtGdEZCeElybjYvU3VORG5NMGtEbUJCR01E?= =?utf-8?B?WDh0ODFBTURGNjlSR21wS2hrU3hlWWRQMEFqa294WUt0d0VhaVZVcGs2YnU0?= =?utf-8?B?V3FzMGV3czhOSGd2b0lXZlRjTXFLZ2ZnUnFEWS8rcGY3WWN2cmhHQUZrUXAw?= =?utf-8?B?UU05KzhvdHhRY0RhcVk5L05UWDZQcFlkNlNZbXUrMEFEbDR6NHNxVk4vMXNr?= =?utf-8?B?ZkNJaENKVVZuZ3NUWVYwL1duZDM0d05xa2RpV0diT0NUTG56akNRZmpzMmhi?= =?utf-8?B?ZnFyUVJXaVY0OTh0KzVpS2MvbVdVQ0FBc0JJSnZ3U0didHZNK2VXc21qVjNr?= =?utf-8?B?Y0Z5djNYSnZGcDVLTGhuMUZiWWd3cXQrcjVhUWhzYjFHMW9SM1ZPQ3lRTjZm?= =?utf-8?B?QlUvVE9JOUd2d3h1bjViSE9DdjZBN3JiWm9CYVQ0ckRDQ1pncW9EL3l4c0xG?= =?utf-8?B?bFVkM01ROWJuZmM4a2dwaVVSWFJoYnhhS2hLY2NaTm5VOUJYWldCTEhXZHdo?= =?utf-8?B?YVFyRWV1enhkdFJkUUNvMjFDSG9qb2dWM2Uzanpta1lLb1FTSkVRVGJlbGFV?= =?utf-8?B?c2NOZ3hMbzcwbVNTRWMzWHMzVkVSWUx0SHBad1dZVUEwY3N3VjZvbU05Wk5z?= =?utf-8?B?Q1Z5VjlkSlBYcUZ5N3JhNW1WcDRPNi9qa0VCcU1INW9BUXo0aGFPN1FMTzdZ?= =?utf-8?B?NTNEWWo5RHJGUUN5RWJ5SzV3ZG4rTEpyaFRsdk9nYXEvWHYza3VxZDFqOThj?= =?utf-8?B?L2xSUTk3RTVHY3FvZytNSUVwTUJodXNMUGNxSWFuWGEwbXJIRmRpZ3o5N3hY?= =?utf-8?B?Zmx0Y1czZ3M5YndTMUhVQVhLcDl6TTBUNGJLc2pRTW05ZENiMVRoeTh2SkVS?= =?utf-8?B?YUNQNVBCbVErWW5lSmFQQW1FOHhaMkhUVGo5QkxtQi9pNXpWYVpZNzdXMVRK?= =?utf-8?B?SGhLcXd5ODRrdnRMelNyWVBsNGZSTXZpbFFzSnRUaEJSeW1hQVB2N21yemV2?= =?utf-8?B?dWdIcS9LUUMwMHRwL0VjMFFZMHlJQU1FdjZJUlpYNEkvM0pJazZabGtjTWZ6?= =?utf-8?B?WkhqSTFsL2kzUTNIODc0QUxHaWFkaU5UbjdMSVlFcDFtM0IzUDdPQTMyd1pk?= =?utf-8?B?cXl6VkozdDZwS0l6czJCNEtTc05ualBsbHBiVHFXZ1hWU2tkL0M1VUxxandC?= =?utf-8?B?cDRveDhrTjh1WUN6cFpMR29rakc4THdsdVp6c3ArdzBqQjVIV3c0RHJpbVBz?= =?utf-8?B?WmVCcjBMb0J4MUtCWlhFZThXMzdJaHkrZnpyWWFOYno2Rnh3UkZiMFp6VnE1?= =?utf-8?B?ekx3emFmaWtLMTRxbWM0NjJpOUcyMzNrc0lWMmVDMnpDOHhtOVVGb0JJajBI?= =?utf-8?B?dTJMVGFzRWZ4SFRLaW8rbXZGeisyK211Wm5TYVdiU01FV1VGVkJtNlVSLzdO?= =?utf-8?B?b3RJR2lVeGVrbmxLREJKZ003Vy9ZZG0xWjYvVmUycEYyYW8wNGprd0NKaXJ3?= =?utf-8?B?bHFpaHZhOUZwdXk0d2tTVm8zbVZzZXR0ZjBqNHJlclZMc0dBaFE2aGk2dU5W?= =?utf-8?B?a2hIT1lMQzZTZnptMWFSUG1NRlFKSTc5V0dEWW9WUGlhYldJZkMxL3lhTXho?= =?utf-8?B?M3dJM3p2ZUZlN1NYNXpPcEd6eEtWbHFWdWlTRnRNTjljZFhMTnFzL2lXZG1z?= =?utf-8?B?Um9xZDhaNERRVk9sR0dOZWNuWW5DbFI2TnBxK0pBWkNNY09aTktTVzFIYU1T?= =?utf-8?B?c2ZZVGtJOWxhUlUrUkd6cnc1MkNSQlNneGFUY2dsVCtCZUxMV1cwV2dNZk9p?= =?utf-8?B?VlNsbU82Q1VKQzV1N0UvdDBTYWM3Q3RLd1FNRVdDRkNqamdxaU55bktqWTVI?= =?utf-8?B?My8rWUt6VENSMzR2RmowZlkyWXRBSjhoM01LbnZLaGxCKy9Fc3JzcVozK1di?= =?utf-8?B?a3BrRys2cEgrTGdNYUo1OVJaUTBCTUpYTFg3T1BxSmg2RTlrRXN2cTRNbmNw?= =?utf-8?B?Z1ZMUEI4bHZ2RWhOQzJpVC9DTDNrcW14TERWbC96bEtCcjJBN25sVGN0YTRE?= =?utf-8?B?bTZ0RmNXeTBIRE9IaXAzQ1p4M0hhb3RNaWpjQ28yTk1qcll2dnphNjB0SGJN?= =?utf-8?B?WVo1Z0t4KzJPNE8wVHJEQ1k2bFVFdk54a2UwdXFsWXNtbmI2RGNycVA1cDFF?= =?utf-8?B?WHA1VnVvMVRrK0lHYUVJTXF1R2FyVm1OVWZlL3lHL0xXMk9wMTJ1NkwzMzI5?= =?utf-8?Q?vfF4LttvzxFZHOUPQT?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: d8b4abdb-bbdc-41f2-e857-08de6469a506 X-MS-Exchange-CrossTenant-AuthSource: CH3PR12MB8660.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Feb 2026 03:50:03.7811 (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: yLEsfqacoLtm9nj2OftaGXmduR85Kid2090+tXZJLuP97qjMEAuaQIyTx9h6/C6cBGLRkRDvcMU6nXFibaYyFQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB8977 X-Rspam-User: X-Rspamd-Queue-Id: 2418E140004 X-Rspamd-Server: rspam07 X-Stat-Signature: 5kcd7h54w9faz7qhphmjfrjz1n7do43m X-HE-Tag: 1770263406-374004 X-HE-Meta: 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 PdQcPouU 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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 2/4/26 1:59 PM, David Hildenbrand (arm) wrote: > On 2/4/26 12:22, Kiryl Shutsemau wrote: >> On Tue, Feb 03, 2026 at 11:49:45AM -0600, Pratik R. Sampat wrote: >>> Confidential computing guests require memory to be accepted before use. >>> The unaccepted memory bitmap maintained by firmware does not track >>> most hotplugged memory ranges apart from system memory annotated to be >>> cold plugged at boot. >>> >>> Explicitly validate and transition the newly added memory to a private >>> state, making it usable by the guest. >>> >>> Signed-off-by: Pratik R. Sampat >>> --- >>>   drivers/firmware/efi/unaccepted_memory.c | 47 ++++++++++++++++++++++++ >>>   include/linux/mm.h                       |  5 +++ >>>   mm/memory_hotplug.c                      |  2 + >>>   3 files changed, 54 insertions(+) >>> >>> diff --git a/drivers/firmware/efi/unaccepted_memory.c b/drivers/firmware/efi/unaccepted_memory.c >>> index c2c067eff634..359779133cb4 100644 >>> --- a/drivers/firmware/efi/unaccepted_memory.c >>> +++ b/drivers/firmware/efi/unaccepted_memory.c >>> @@ -209,6 +209,53 @@ bool range_contains_unaccepted_memory(phys_addr_t start, unsigned long size) >>>       return ret; >>>   } >>>   +/* >>> + * Unaccepted memory bitmap only covers initial boot memory and not the >>> + * hotpluggable range that is part of SRAT parsing. However, some initial memory >>> + * with the attribute EFI_MEMORY_HOT_PLUGGABLE can indicate boot time memory >>> + * that can be hot-removed. Hence post acceptance, only for that range update >>> + * the unaccepted bitmap to reflect this change. >>> + */ >>> +void accept_hotplug_memory(phys_addr_t start, unsigned long size) >>> +{ >>> +    struct efi_unaccepted_memory *unaccepted; >>> +    unsigned long range_start, range_len; >>> +    phys_addr_t end = start + size; >>> +    u64 phys_base, unit_size; >>> +    unsigned long flags; >>> + >>> +    unaccepted = efi_get_unaccepted_table(); >>> +    if (!unaccepted) >>> +        return; >> >> This can be tricky. >> >> If we boot a VM with <4GiB of memory and all of it is pre-accepted by >> BIOS, the table will not be allocated. >> >> But it doesn't mean that hotplugged memory above should not be accepted. >> >> I don't think there is a way to detect such cases. >> >> Your check is probably the best we can do, but it means VMs are going to >> crash if memory accept is required by no table. >> >> This is ugly situation. Agreed. Breaking hotplug for VMs under 4G is absolutely not the way to go. Would it be worse if we call arch_accept_memory() if the table doesn't exist? The table is primarily to operate on the bitmap's entry. We could wrap these accept calls within an arch check for TDX and SNP guest if the unaccepted table is NULL. Or, less preferably convert the panic() of the existing arch_[accept/unaccept]_memory() to a WARN() instead. > > It's all starting to feel .... very hacky, sorry to say. > > This should all be easier. If we expect memory hotplug (SRAT), why can't we just allocate the bitmap properly? > The unaccepted bitmap allocation happens a lot earlier than SRAT parsing. So to get the right range, either we have to duplicate some of that parsing logic earlier, or, replace the memblock allocated bitmap later. The first one is a bit more hacky, but the second one would require us to the change the original unaccepted struct from a flexible array to a pointer which might break kexec. Neither of the approaches seem less intrusive than the other unfortunately. --Pratik