From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.14]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AF26014D283; Fri, 18 Jul 2025 15:12:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=192.198.163.14 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752851547; cv=fail; b=DFM5SGp27+ZAuq2ujBB2GwDjlAsvKf/NgJOlE6PJLFwoF5GJ+uUkDCoZMkOmGkjPfHZXwaU/xKe+MF13DNnHrKTDX3DdFPjbmmIaqMPsKSItFXZRSL2q7v5/YagsluxkPDp87MeUUUNe+RF5bGRMJOnpyzzot68HsTCejhEGMb4= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752851547; c=relaxed/simple; bh=hcGbN1pM1Ofo8LmpK5tOvJmGFXnwnoLfyAIHG7ljmHM=; h=Date:From:To:CC:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=CUCd8D7ttDLBYmwVVcH9z9cIZm21vF6nhDwuL78LTcYRdSW9HcffZMhKyYJWh09k243RgaB1WRA4Fwq9GUWKzFKzQSMXC5ajKLEXBUL6kp3w44RO+D0qkeQcuA9uATnyEhHO6mYJYnBdLrySY/fDHzP/DtprEnrb/ar+LoA2xds= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=IJgsx7d1; arc=fail smtp.client-ip=192.198.163.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="IJgsx7d1" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1752851546; x=1784387546; h=date:from:to:cc:subject:message-id:references: content-transfer-encoding:in-reply-to:mime-version; bh=hcGbN1pM1Ofo8LmpK5tOvJmGFXnwnoLfyAIHG7ljmHM=; b=IJgsx7d12zaRQF45kAOVO+1LDDYrZyoXsHHZIalrenKnAu96lIDTVzZ1 WRjNMyQUkWmEvtTM08R3iMKWS2W7LeM5AFDeFeBDpSf3wRg5RyuMi/wL8 XNwXFvW4nH/FHZ9oN9BWyEbwvCYYrA70dLbz5WDrLM6wPvUnK3s/hpeYg 7DnuLTeo2z8MOn/97HYLkY1ivlHjnObptfw3jRMrlNyPysM/EpYhwCeqZ ADnhkPweBAqDzllJ91POmOPiqGVmfGVqCjT/CQ/hGcV4HmsHpsSfyaARk UmCd0Ra181duolKQBnfouWyHP1tjlTzNo5ZtLSG75ov2/qcwIoM/elvAE Q==; X-CSE-ConnectionGUID: RJRCPhenQ9u9K+zGwViEag== X-CSE-MsgGUID: kcOA5k+3QTOWmgNGl2UJ0A== X-IronPort-AV: E=McAfee;i="6800,10657,11496"; a="55233653" X-IronPort-AV: E=Sophos;i="6.16,321,1744095600"; d="scan'208";a="55233653" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by fmvoesa108.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jul 2025 08:12:25 -0700 X-CSE-ConnectionGUID: dAeHgryXRWK4sFDCyKFj6w== X-CSE-MsgGUID: HbjIL0JTQ42NZR/mjVwYjg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,321,1744095600"; d="scan'208";a="163708357" Received: from orsmsx903.amr.corp.intel.com ([10.22.229.25]) by orviesa005.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jul 2025 08:12:23 -0700 Received: from ORSMSX902.amr.corp.intel.com (10.22.229.24) by ORSMSX903.amr.corp.intel.com (10.22.229.25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1748.26; Fri, 18 Jul 2025 08:12:21 -0700 Received: from ORSEDG901.ED.cps.intel.com (10.7.248.11) by ORSMSX902.amr.corp.intel.com (10.22.229.24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1748.26 via Frontend Transport; Fri, 18 Jul 2025 08:12:21 -0700 Received: from NAM12-MW2-obe.outbound.protection.outlook.com (40.107.244.60) by edgegateway.intel.com (134.134.137.111) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1748.26; Fri, 18 Jul 2025 08:12:20 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=vVX6Fx7eg18TJx36vNhTnl8zuysfvWT38vreutSVrSbHUfudqNMtIeFyN1xPDSukmiTHOZWBpWrCnSFdprYb4pEWQR17/RzYRXKLsLfvyx7+C0uos9u1GB31zM3kZmg4AwyWRQ74WfZRNtkqk42J1amsiH2MA2xFDLIA7eQgTrvYYc/8qih5X1hFFdRPG8xGgeV2zWI9IfqyGYOWXpkWEmoRYe0lFVzeMEBm/PtSk1yLJQIEInTraTsztt5Qw/qC6H1tITqo/YiSfdil19mX9WrCQc5VDQ5QrMxcgbWxr1o9qlq4v2Vc8FRluKfem4ATqQCOsYDx+WPpJh01Nn7ipw== 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=We3KXD8ls3nuzRx8BgUTt0rmqz4/ZnJLTeVxbFhsB6U=; b=LsxqBsh0n3DZ35v+HOJxgoLrQFWWM/w/5oDbqEDkpBM7GX7OPOy+/JLIdYB9qFmRw8JoRwM5Yx1B/5zEZ7FvlKvcpnAGo+UXK4NZkgjQ5Uz6NAMfTJ4hRE+16QhHtrk3sZh31jOVQ1MzDZ2pLaQTTmrb8Oc3Mo7R4POE0vD233PlOr6eAQspkMEax6YN9Fwvz08fix8luw/3zTYv6+BEvwpYhBw4RaHf0G1a0zyes7BzJ0i2wochtZrGAkDb8G3F7bc9oYQzeax8+ypcjYOPto6gqtlD0E+Eh409m1KOYtWlQwAYID7jSLimBaDvOHBqq8Srn1Q5257LM+m7/I1Vvg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=intel.com; Received: from PH3PPF9E162731D.namprd11.prod.outlook.com (2603:10b6:518:1::d3c) by SJ2PR11MB8421.namprd11.prod.outlook.com (2603:10b6:a03:549::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8901.35; Fri, 18 Jul 2025 15:11:48 +0000 Received: from PH3PPF9E162731D.namprd11.prod.outlook.com ([fe80::19ef:ed1c:d30:468f]) by PH3PPF9E162731D.namprd11.prod.outlook.com ([fe80::19ef:ed1c:d30:468f%5]) with mapi id 15.20.8835.018; Fri, 18 Jul 2025 15:11:48 +0000 Date: Fri, 18 Jul 2025 10:13:07 -0500 From: Ira Weiny To: Xu Yilun , Ackerley Tng CC: Yan Zhao , Vishal Annapurve , Jason Gunthorpe , Alexey Kardashevskiy , "Fuad Tabba" , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [RFC PATCH v2 04/51] KVM: guest_memfd: Introduce KVM_GMEM_CONVERT_SHARED/PRIVATE ioctls Message-ID: <687a6483506f2_3c6f1d2945a@iweiny-mobl.notmuch> References: <9502503f-e0c2-489e-99b0-94146f9b6f85@amd.com> <20250624130811.GB72557@ziepe.ca> Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-ClientProxiedBy: MW2PR2101CA0002.namprd21.prod.outlook.com (2603:10b6:302:1::15) To PH3PPF9E162731D.namprd11.prod.outlook.com (2603:10b6:518:1::d3c) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH3PPF9E162731D:EE_|SJ2PR11MB8421:EE_ X-MS-Office365-Filtering-Correlation-Id: 1aeffe16-6119-4e18-c7d1-08ddc60d6a60 X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|366016|376014|7053199007; X-Microsoft-Antispam-Message-Info: =?utf-8?B?cUFjS3dLUmc1aGdWTFY2NzhHN1g3WUZHQzQwTGZ6Tk5tMmtrcmJaU0RnN1lZ?= =?utf-8?B?Q1gxUks3WU1GM20vaFJ6STRDL2c4Z0ViUDZmVEtZZW9HWExPSlNZamtJNFdQ?= =?utf-8?B?eU5LbzRsaDJ5YXpaL0hjRW1oV2FUM0hSQjVPSGFLV01aQnhKYUh1ak5YRGdq?= =?utf-8?B?ekcvR1JBanQyUzFuVWFsNG94T3ZWajhOMDRnMEpQSVMxSVhJOTdWSjM5dkY2?= =?utf-8?B?a0k1Zk9uQzdPVVhjUWRQQ092Mld5emV0K2R0WklkNUZBeHdnTC9lUUJWSUNh?= =?utf-8?B?dXEwYThvbDNmSENEbHhzeHlySytBNnVDbFljMXJhMlhvMEJoUTBDcDJyemVr?= =?utf-8?B?WmZraUdhdEJhcmd0YXdGT3VwRnNqM210Q3pNdFUvOG9mdzNTd2FvOXpmbUJO?= =?utf-8?B?dklwNUxLZjhLdnRVd0ROMXFhNFFwdUtoaFRWSmg2NWFhNi9Qa1NURVM3K0lZ?= =?utf-8?B?SzNDZTJ2NFcrZi9XZnBzbjNkWFR4THdjRTRsby9DKzVKc2RvS0lhN2hLYWZo?= =?utf-8?B?MExJZm9wTG9ZLzUwYk44VGRURVpjTm5KWEhxdFNGY1I5QWw2a2xiYlVlOVlS?= =?utf-8?B?QzFYVCtCODhzdVBFY0ZTVXBqVFZYT1VzM0Q0bjAyZVhNRTRBMmV1MmwzS1pK?= =?utf-8?B?dUYvTkdtdVczT2lSRWU3a1J5VjJxbVZJdm91MWNFRHM4Zjk4UlNxK21kY0Vj?= =?utf-8?B?Z08xa3UzR0tQYVlvVTI4RE5vVldLamxQeWtjcGVZeUNPN2NBNk42ZHdSU3pI?= =?utf-8?B?WnZmUUEveko0SGdJbTNwVWlGMGh2OGJUak90VmRNZFNFaWZleHlSVGlkUDhz?= =?utf-8?B?YzR5emdkOVlHYmc0YjhqKy93M3RQQWk3bElnbjEvMzR6bGZETXZwNmFPbDc1?= =?utf-8?B?RVlia0pjRE42RTRVcmx3N2t6aVpkZmtLWlRZOEx2WksvbXV3dGlMNnU1NmJP?= =?utf-8?B?V3EyVmJwS3BRQmdFS2xCc2QxL2ZyMjF5TVp4YVBXK0dYRVVRTVJ4QTh4ZldU?= =?utf-8?B?RmdFMnRoWTdObDNLc2NVWXNvd0JzTzd0M0JpcHc2Y1RDUUZyRUYrVWVtTjBR?= =?utf-8?B?ZnIyVWxaU1gvZ0tLZTJJY2tMeTVJc0syYURpOVlpbjJYWWJxYnl1U3NKQVY0?= =?utf-8?B?bGJTbTFLOTRZaktmWXpQcTdNaUtxR1d5cHM5QzU2eHpsNWxnb2pWUXdzdVRD?= =?utf-8?B?ZWs5WEY2LytVaHNHLzAycWFBWXRBZnVudkJYYUVzZjlNdkRlcHFTYjE0Y3NI?= =?utf-8?B?TzVrWEhDWHhyUlUvMmJtNmlFeDJqaGwwRG0rV2lvby9uVmVoMFJkQStVZlRm?= =?utf-8?B?c0NhSEM4QStOSWIrNHlsTW9HalFkM3V5bmliTmpXaU93VkxrT2gwMkRqOVlX?= =?utf-8?B?UllQREh2L0lnNDdBLzV6SlFNRElmaCsvK1l6TVd3cFBHY25wQnEzc3kzRDJC?= =?utf-8?B?UDV3TXppVHpBTFo4UUhpTHV4dDVlbTVyQWYwanNGV2lFYWNKeU1LWlpvTlRO?= =?utf-8?B?WHRleXk2d1dGdXRSWnc5U0JnTEd6RktlSjhkVEdvcFNXZFJ2dVFlcUVUTldq?= =?utf-8?B?c2J5c0FXTHllL2xvVkwrS2x4OUdqd0xJYllGOW01RVdpT1lMNGZMajVjSFJK?= =?utf-8?B?S0tBOGo5RWVkcHdDNUpOWHVNTHBGbG1LY2JiN2pkWGNSaDVlZWNLR3d5eXhR?= =?utf-8?B?WUwrTU9VbmxwZjBEaGNDYVBRbmJKY3g4RWxjN0kzMkllcEFlMFN4WFRyNkV3?= =?utf-8?B?R3pwZVBDT3owbmRxZTVHa1dPRjVoaFpCMUY2YjdqTDl2NnBOakZURVRHNlE2?= =?utf-8?B?T3l5bWdLRnc5a1M1V2R1dmNhZXc5T1R6bWI4QnVDNzAyOVBRUmRIZVNCalNh?= =?utf-8?B?Y0VleUpTanVUSDdnS3htbjQ2QWh3NXJOTWZPbThZRmtpdGFHSTJEWkZUYWVl?= =?utf-8?Q?sj9ZR+jaRuM=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PH3PPF9E162731D.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(7416014)(366016)(376014)(7053199007);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?eVNtWlRINEN0WEJPTnhDdTFuTmtUUzVmTG9QSVd5UXl1QWlRZGFTSVJvdFI1?= =?utf-8?B?YUdrNEZkTkVINTQ3ai9VTVhVZVRrd0VVb2UybXRjMEJFZUhld2U4T1g2TGRt?= =?utf-8?B?ZVRFQzJtRHhnT00ydGhudmloZmpUNFZPbW9EMkhHSk1LcmYyVXFRSVZIN1pU?= =?utf-8?B?Q0dFRkdaYmgyMTdoZGhmUjRSUDc3OGorUkNpRklOVEROYnNmRG05a2JGWC9x?= =?utf-8?B?V3hXSk13U3BaWmxaNDRkRmowdW4xRWVmdnVUMXdycUNNd0JvOXJ0OUk1RlVP?= =?utf-8?B?cnJRSzRKM05MNjEwd213UVltTW94NnpoTDFWaCtHVmpzMDRPdkNwYlRQcWdO?= =?utf-8?B?dFVrTVZaVGNGRlZPZGlnb3NMelF6WXBGanNSbld3RkMyK25zdHVLVXN4eGE4?= =?utf-8?B?S0huMFZGUnpyMzZ5bWZTVmU5TjRrbWs4bk9FTUVVWnFGZ1I1c21vTUpiRzJn?= =?utf-8?B?Z2xVcjV5RDVtR0RhVjdQdEZkbHlWSFNXY1RDZXdkbUJOSEY0K0ZBV0o2cUFY?= =?utf-8?B?djRobGJ1YWY0N0h6QlFxVmNDanRML1FGSFRob1pySGRqU0JhZ2lJYnpEdjI3?= =?utf-8?B?OG43bWEzWEl3bVdxR0ltMjBIMXN0cmJSbWs2bGp3clJ6SVhTeWZudnBkUWto?= =?utf-8?B?R3V4aGV2YzZva0s5WUtxZU42QUFXWHM2dEpEemIrYkk5WCtIQWtJQTVNTEFL?= =?utf-8?B?dlkxeC9yMEpPdVBrajJYVkFnUUdGS3VvN3EzRVk0L0h0U2FTaXNTWUxSaTdk?= =?utf-8?B?YUI5MHp5RWpObmNwNFB4OVNXMU1DYXVJVzhZODRxNHIwam5SdW5HS1RTdFM5?= =?utf-8?B?c3J4YkhiaUlVd0hiT3ppa2FWUWVOS25TSXNzSXhnV1V3M2dSSy9ydmZPanNI?= =?utf-8?B?UHdCd3JhN3o0NEJ5bU03dzVhdWhuejZzUEoyQUswdTVvMjM0QzRLOUpWYlFP?= =?utf-8?B?MkZLY05qb2s0RTE3eFlTMVhJcWNtMjYwNUNaWmlMNld0MzF1R3YzcEVXeGx2?= =?utf-8?B?YXN3RE9WRUx0NVNUWXNMZWtiUmRtaThrV3d4Rk5xTEtVOCszbWxKdXJEaVNn?= =?utf-8?B?Sko3bXdka3JCVHZUa21meCsyOEU0cmZxZ1FwdU9zN1NvanlYRHE3bUVna3d6?= =?utf-8?B?aUw5UXRrM3k4Sng1TGdCMTNRZlJCR1Ivai9qbHdGQloydTlKNFRpVTJqK3Zq?= =?utf-8?B?N1NxMm8zVjExd2Vmc2ZaY3VZVlBlL2pGV2NBMnFaNEsyNWVwekQ0UUZNam5R?= =?utf-8?B?cWhzTmUyYjV2ekRFbUNTRlNYVFJiY3hmYzdBMWNZYUkrbDZadi94Y3pJRk5I?= =?utf-8?B?VzNhZGR3SGY1UDkwRktDRjUwa3d3bjlMMGFOejd6WkRjRnIvOFhpQWNwMzhE?= =?utf-8?B?VzRER0Zid0pUUTVUbVlzY3hDTktoOWwyUXFYUzZlUU1TMU5BY1EvRWFLYnRF?= =?utf-8?B?TjVqa2hFVUZndExiNFdZeGtrb1VxNzBqMXBDblhaQjk1WlVaYzArcDUvOFJY?= =?utf-8?B?UFNTMkFxNFc3Q2xaVGtuMTNXK3lrWHltQXFrNXc5cGpXb0F6bnlSZXEyZTNw?= =?utf-8?B?ak1rNnQ1akhNL2tGZTZibnY4djRWd29MTU5tM0tYOHFnM3k1SVFqUklranNt?= =?utf-8?B?TVN6clp5Yk1tZ3hyTTg4NndpWHdpdFN5SFR4d1R2UzM1MVBBbXoyNVV6UE5m?= =?utf-8?B?dERITlZVL0FoTDVDVFpCd0RnKy9BZjNrTERMcjk2ZTRFblZaMFMxbndQdldX?= =?utf-8?B?Q2R3TjVhODZhOG9rakcvb2ttUTFXZjhKRXZVNmlQZ1hYUitJTUg3emxBSjA2?= =?utf-8?B?SFlTWTlrblAwVUhsVG1Rd2dlMHc4WE5va2xMK3ZHR2NIWkFEZlNUWm5CcnZ6?= =?utf-8?B?WHZEZjlDbUNuNllQZS8zTjVXaS8xOUZmQkhHZGloOERoZlVleEFnc21KMTV3?= =?utf-8?B?K3ZaWnlRemN0MytzdVFZVDU5ZlpMTHVGc2grVXVyV1dpRk0ySDZ2Z3pIcE5R?= =?utf-8?B?T3dpNEVET0xReURNeThzZEpBaFhyMWVWaWR0UFQxcElNWGxlbEhBZE9TOHBO?= =?utf-8?B?bnZPRFlQbW5VeFFIcXZURDJVTkVQb3BMNjlwR2hKN2x5TFZlMHBxL2I3eWda?= =?utf-8?Q?X41A9aqZ843wCBMxLPbVGUV0c?= X-MS-Exchange-CrossTenant-Network-Message-Id: 1aeffe16-6119-4e18-c7d1-08ddc60d6a60 X-MS-Exchange-CrossTenant-AuthSource: PH3PPF9E162731D.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Jul 2025 15:11:48.0350 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: v9j/xvJdxzQ7R80OPyuN2XBIJpzMShd4I23YXAd+XziiWo7sQ23MkKxJXxEdEy/wIURbr81COYKQpk5yQoJeXg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR11MB8421 X-OriginatorOrg: intel.com Xu Yilun wrote: > On Thu, Jul 17, 2025 at 09:56:01AM -0700, Ackerley Tng wrote: > > Xu Yilun writes: > > > > > On Wed, Jul 16, 2025 at 03:22:06PM -0700, Ackerley Tng wrote: > > >> Yan Zhao writes: > > >> > > >> > On Tue, Jun 24, 2025 at 07:10:38AM -0700, Vishal Annapurve wrote: > > >> >> On Tue, Jun 24, 2025 at 6:08 AM Jason Gunthorpe wrote: > > >> >> > > > >> >> > On Tue, Jun 24, 2025 at 06:23:54PM +1000, Alexey Kardashevskiy wrote: > > >> >> > > > >> >> > > Now, I am rebasing my RFC on top of this patchset and it fails in > > >> >> > > kvm_gmem_has_safe_refcount() as IOMMU holds references to all these > > >> >> > > folios in my RFC. > > >> >> > > > > >> >> > > So what is the expected sequence here? The userspace unmaps a DMA > > >> >> > > page and maps it back right away, all from the userspace? The end > > >> >> > > result will be the exactly same which seems useless. And IOMMU TLB > > >> >> > > >> >> As Jason described, ideally IOMMU just like KVM, should just: > > >> >> 1) Directly rely on guest_memfd for pinning -> no page refcounts taken > > >> >> by IOMMU stack > > >> > In TDX connect, TDX module and TDs do not trust VMM. So, it's the TDs to inform > > >> > TDX module about which pages are used by it for DMAs purposes. > > >> > So, if a page is regarded as pinned by TDs for DMA, the TDX module will fail the > > >> > unmap of the pages from S-EPT. > > >> > > > >> > If IOMMU side does not increase refcount, IMHO, some way to indicate that > > >> > certain PFNs are used by TDs for DMA is still required, so guest_memfd can > > >> > reject the request before attempting the actual unmap. > > >> > Otherwise, the unmap of TD-DMA-pinned pages will fail. > > >> > > > >> > Upon this kind of unmapping failure, it also doesn't help for host to retry > > >> > unmapping without unpinning from TD. > > >> > > > >> > > > >> > > >> Yan, Yilun, would it work if, on conversion, > > >> > > >> 1. guest_memfd notifies IOMMU that a conversion is about to happen for a > > >> PFN range > > > > > > It is the Guest fw call to release the pinning. > > > > I see, thanks for explaining. > > > > > By the time VMM get the > > > conversion requirement, the page is already physically unpinned. So I > > > agree with Jason the pinning doesn't have to reach to iommu from SW POV. > > > > > > > If by the time KVM gets the conversion request, the page is unpinned, > > then we're all good, right? > > Yes, unless guest doesn't unpin the page first by mistake. Or maliciously? :-( My initial response to this was that this is a bug and we don't need to be concerned with it. However, can't this be a DOS from one TD to crash the system if the host uses the private page for something else and the machine #MC's? Ira > Guest would > invoke a fw call tdg.mem.page.release to unpin the page before > KVM_HC_MAP_GPA_RANGE. > > > > > When guest_memfd gets the conversion request, as part of conversion > > handling it will request to zap the page from stage-2 page tables. TDX > > module would see that the page is unpinned and the unmapping will > > proceed fine. Is that understanding correct? > > Yes, again unless guess doesn't unpin. > > > > > >> 2. IOMMU forwards the notification to TDX code in the kernel > > >> 3. TDX code in kernel tells TDX module to stop thinking of any PFNs in > > >> the range as pinned for DMA? > > > > > > TDX host can't stop the pinning. Actually this mechanism is to prevent > > > host from unpin/unmap the DMA out of Guest expectation. > > > > > > > On this note, I'd also like to check something else. Putting TDX connect > > and IOMMUs aside, if the host unmaps a guest private page today without > > the guest requesting it, the unmapping will work and the guest will be > > broken, right? > > Correct. The unmapping will work, the guest can't continue anymore. > > Thanks, > Yilun