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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C5AFBC44500 for ; Thu, 22 Jan 2026 10:25:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:MIME-Version: Content-Transfer-Encoding:Content-Type:In-Reply-To:From:References:Cc:To: Subject:Date:Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=wXDPqyiLdtmkhDH20FlxniffaDaFHsn7ICjIijsgMVg=; b=XfkZ/1CA4bS9NFM3jw/RRs75Sv AMDs85iTClk4CLSSU5/gJW6MvtavP92/rJ88C47lavIH5KG9G1RD9Iorr6P+doUdLPwMIRuPccmfG t4mP/r6qYGaa6ZAckk6/FIDffNroncyoHaskWJp4GrABqynLHgb9rJrRFVpkeQHKD0zegWB6Mdcj+ cqa9jJ+1FsTdGa67YSeDaEKuzI2YdhG9reMyRrwT7051WkF5V2AJ6B61W604Z+n0m7BA93P39kgew 5dIztEskUEY2Il7OgnMR4jxrzyoGk+d0PWRKUcvP5SXFtcLku33q4XQ8G9z6YMGYBpiIwEy1Tyl6A IHZrEjpw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1virso-00000006pvd-1UUm; Thu, 22 Jan 2026 10:25:46 +0000 Received: from mail-westcentralusazlp170130007.outbound.protection.outlook.com ([2a01:111:f403:c112::7] helo=CY3PR05CU001.outbound.protection.outlook.com) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1virsk-00000006pv1-46WZ for linux-arm-kernel@lists.infradead.org; Thu, 22 Jan 2026 10:25:44 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=cX6roxmy1QPbTnYrCOmqTFeaoE0nJzIxFzDhZ2GqHh65Y9I/imWDA9HZXahDI/gQvG88rznwCXsCj3j24Jn61TYjxrg/XQE/mOaccFMVf1UsaHUZAzUpY7gXTWkCKD/sdsQs7WyNJzNJX1pbhHZPrXIe5Ppe/NDSsvCJEJJzKX7o/1pj3RbhZJRZqAFysmRbxUPi+4naBqJCdfp+0oNGCujtcvb/Sok4qbVELLihJjaqRSQSl8a5QQ3u8f1TpdxfzIxie5AHLFjWDIvwNPpjU+n8WHFim22uB2ztvVeT+ZE6xgdJLZTDjDaxQGLh5tdWJcYo78xWmtkA7XUHKQNJrQ== 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=wXDPqyiLdtmkhDH20FlxniffaDaFHsn7ICjIijsgMVg=; b=aofN4Sq7fHVrvOi5S7ttncSq5WM44vyd+FNulwU8cOi6BqCIiYxk0xc+TxPXugx8tdtgSNZhUC7Wk1JrTUg94hpEQTElIqpXmiXaFlb2rTdpFhFldYBE//dQZ68U2OsfMQHC6LB7RmD1W7tq6O/KCbspcFMPabTlgX1lpPn0v44BFMagS/YoPH0VEla06z4H8aaYZXJyj8fXPRLYOVV8f2WbL9vEEAbgQWDej1OgqizkxsQsjkXaAfaVO2fasJx10xJAdkHLo1wzH/Zu2w+m/pjjZZXQkGkqQeeieZ0qszjkAvqrXK+Dh0I0MkCVek/cgkBSIHyGDH6Wl/dE9Tp/6A== 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=wXDPqyiLdtmkhDH20FlxniffaDaFHsn7ICjIijsgMVg=; b=15mqkIwhrW9rHMcZmEht6XgWgxbbhJhsfGJS0Xs7oRcFXCeAfWKkX74f/U+3jg1kf0DovFQsDngt0wBkl9391uqbksg2/eaiXJXkZsY7Wz7UBSXDqdtLK6NBHWyWapXCU5CMDC8S5P1Ds0HmeveN/IQMbi2ZeMU4xvNQC+dJEwM= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from MN2PR12MB4205.namprd12.prod.outlook.com (2603:10b6:208:198::10) by IA1PR12MB7710.namprd12.prod.outlook.com (2603:10b6:208:422::14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9542.11; Thu, 22 Jan 2026 10:25:38 +0000 Received: from MN2PR12MB4205.namprd12.prod.outlook.com ([fe80::cdcb:a990:3743:e0bf]) by MN2PR12MB4205.namprd12.prod.outlook.com ([fe80::cdcb:a990:3743:e0bf%6]) with mapi id 15.20.9542.010; Thu, 22 Jan 2026 10:25:38 +0000 Message-ID: Date: Thu, 22 Jan 2026 10:24:58 +0000 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFCv1 1/3] PCI: Allow ATS to be always on for CXL.cache capable devices Content-Language: en-US To: Jason Gunthorpe , Jonathan Cameron Cc: "Tian, Kevin" , Nicolin Chen , "will@kernel.org" , "robin.murphy@arm.com" , "bhelgaas@google.com" , "Williams, Dan J" , "joro@8bytes.org" , "praan@google.com" , "baolu.lu@linux.intel.com" , "miko.lenczewski@arm.com" , "linux-arm-kernel@lists.infradead.org" , "iommu@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , linux-cxl@vger.kernel.org References: <20260121100307.00004e60@huawei.com> <20260121130315.GE1134360@nvidia.com> From: Alejandro Lucero Palau In-Reply-To: <20260121130315.GE1134360@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: DU2PR04CA0263.eurprd04.prod.outlook.com (2603:10a6:10:28e::28) To DM6PR12MB4202.namprd12.prod.outlook.com (2603:10b6:5:219::22) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MN2PR12MB4205:EE_|IA1PR12MB7710:EE_ X-MS-Office365-Filtering-Correlation-Id: 133c675d-a8a7-4914-c44b-08de59a0886f 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?WStpUlJ2Q0xXb3FyNWFvNlJlMXpzemZZY0IwUzVzbTdCQWxwRE52VlVRMDhn?= =?utf-8?B?bTdyWG5VcThqRldxTzZIU1dERThGQmNuWGxYRkVaWkFJdFhvVy9taE81SXM0?= =?utf-8?B?b0FLK04yRElqVlFxbWlSWGZaRmVNWXd3YUVYUjFEeGc3SmhEUGdSeGVoQUVP?= =?utf-8?B?Sy9Kbm5CdW5zR2Y1UWJSM3B0QWxlR3JQQzhYRlkwQm9NVEVhUWJvUSt3MEt5?= =?utf-8?B?SU5zZjJvYjlyZ2wvaDN1M1gydEpBejVSQ2JNRlo4UlJMWktzalVlTHdiNVlT?= =?utf-8?B?eTBjQmdSUnloV3A1T1VSdGU4Wi9SZXlaRGlWM0ErNlh2YmJCRVFTTXFlcGxI?= =?utf-8?B?T3A5N0JySU50eWVKeFRwSkdkcGVsWDFKRmFkdlpGa1k4Q0thc1JXajVlYzJo?= =?utf-8?B?SlZ4SHpOOXkwWFVUaFYzNmZnUDJNZjM3TkZjUW9QdFM1R0xJbXkwdzFIcUho?= =?utf-8?B?enlZY2orK2JBU0xpQ25RSnRRcTNaU2ZZSkhkUitZNWQ4bjBaUDhybTdPcE4r?= =?utf-8?B?dWtNK0lMdExRTTdYeVcrU3o3MEtvbXJWYVpVc0RzTnBXRTlsZFVYUzIzWGJN?= =?utf-8?B?K1RiQXlYOGg3UmkraXg0N29tbSt1WW5KYWVuS3JlTzVPVkVhMmlpR3RTa1dP?= =?utf-8?B?NlFvd1M1SjQ3Z1dBRERTNmdISU9mV2Z6TEh6Q2ZseFU2QkVKS0FvdC9UbXBM?= =?utf-8?B?UGRIcytJZnI4VjNvSE5jNDFzUTdBdngzaTk3eDZraGJwb2NEaTJnWHJBWTMw?= =?utf-8?B?YzBlUTNWdFc5VytjamlhSlJEd1pIZlQvOU1wNno2czVoOGk0MFhNWXJCQnY2?= =?utf-8?B?WDBnS0pNUG95ZFFPQ0JBcksvczdJSlRTdTlNWFhOZ2dzY29PbjlOV1pBTU9k?= =?utf-8?B?a0pTa0RkRGNPRGc3YmhrR1cvcCtUUXFTYjB6L25XRWg4amliTjBrdk9ndFcr?= =?utf-8?B?Wjd6QVRha05xMmZTWDI0ZkhwaGF6VXp6V2ptanBPSXhvRGQzcVVrdUpBR2lm?= =?utf-8?B?TGUwMWdFM2VLTUl0S3FvYkJRNEx0b3haWkRpT25BTytwR01RZlBJSXZKZlp5?= =?utf-8?B?SlBlWW10RFlDNDhrZ0pucXNrOFlhUDdMblFXVHRmT2xEalpOcU9COUlUSTlR?= =?utf-8?B?YVM5TzZDYVZ0YlptcW80ck9KMmhtb2dnd2QvcytBakpETktrbGNlK1dheFVr?= =?utf-8?B?Yko1SVFmNEh0UWhYZXlRVmVSVnBKdTNWYTJIdjhVaG9ZUlNtVTd4QkVaejJB?= =?utf-8?B?MGxRZTQzM2ljVmdIakZ4eTFRaGgvOFZKK3pHK24xWTlib1BabmRibExjRUdh?= =?utf-8?B?OXNJZjN4blJob2xvYXE5M0p3bEd1NXoxM09SRy8yT1NZZ0x6VGlvNXlGV1M1?= =?utf-8?B?RkxFakhpVU81R1NiMnIwdWh2MWJiRC9JYlJvTU4ySkxvWDBsbzJvWkFpVEl5?= =?utf-8?B?MXMyMTk1QWR1cWM4aW1LdXdWZE1wT1I5VU52cE8reld6a0F4RXFaSmRzWFQ2?= =?utf-8?B?SzZSeHZuNUY1TDlsVE52cVNZa2hJVTZqRXovR3BmYnIxdjBlaVJyS3Qrc3ox?= =?utf-8?B?aHZwQXVEQjRmV0x6M0kxZmt5UW9uS0lHYlBpaTRKQmg1RGErTEtHcWZoK2xB?= =?utf-8?B?WWEzM3JmNnBHOW1nRVRtRitHQVhXUXY5WTdRcHdNWXdicjNESXNOUTdTSWR1?= =?utf-8?B?QWFncEY1UVlLcWxZUmxBMU5jY1cwZXBESys3bjcwaHlUWHlMbWpndk9xMnNO?= =?utf-8?B?UkFVUDJWYkhnQ2ZEUURGZHAwekFsWFVDbk1TNyt6OEpIdGRNdm9yTTYrTkI1?= =?utf-8?B?N1I4cDBkUWxEcVVWVzdJSWhBK1VFSXlLSEtGNHNZNDNwNzZQT0ZPY2grb0l4?= =?utf-8?B?eEM4eHg0U2dxOThrVkFIVHptTHNSNTk1WU9DM29EUWh3RDk2cE0weE50QWpJ?= =?utf-8?B?SHVZbTZHRlNOOFI1Zlc1RmZJYTNMSDdkbXRkOFZFVFBSZWhzcDY3RTc1ajJE?= =?utf-8?B?ZlhzNjBFeXRoTGxxeUdSUWY2WFl6VjRzdE41dElHUldGbVYrU3hGcjF1UHli?= =?utf-8?Q?3anO6f?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:MN2PR12MB4205.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?N2FBYWllN3NKaVpjcGg4dysxQ2hEQTFmamNTZDF3TlY0Q292MUd6RXJqVDdV?= =?utf-8?B?Q29DSTR4eXJyZnhpR0Q3ditkU24wSGFEalppTHVLWWZnWXRlMWVQa1oyZ3Fy?= =?utf-8?B?VG5HK0RvRWEvR3VWYUV3RHdydVUvd3N3UG1MNk5sRVhNcjduYnd1bFIvTVVk?= =?utf-8?B?cmJ2L0laYUJlK3k1U0UxSzkwN3hTTUc5RXVDNG1UUkttU1B1eVREZWRrWW1J?= =?utf-8?B?Q201MUw1Z2tuRHoyUm1NZHZYR28wZU9TYmdmckhsOUF1L0hNdGFvdERaRVFw?= =?utf-8?B?TGU0Nk52bWJBandCWU9vZmw4Vi9RZVdGalBzYmJFbHBQNkZMUVBVb0FVU0lL?= =?utf-8?B?dFFEOTdvMkxNMENBckNwa2laK3B3TE8yUTVMR2hOOXZIMnJmbXpucWdhNUhv?= =?utf-8?B?aEMyS0dIa3IzcWJrKy9iWWJRMHhrUllmTDZ3Ym43bCsxSXFlWlhRb1BKVHdu?= =?utf-8?B?OW5pTUI4UTFkQ29jNWVpeWFERkFaOHo5RFkvYWhHcWswVnpJeGJEbkJ5NkpS?= =?utf-8?B?NGY0Y1JsYU9YZkhXQ3dreEZ5UjJWQUhmQVpyeDkxQjNmdkZlYTJ4SUV6Z1BH?= =?utf-8?B?OEJSY1RoOE1oUXlsRFE4U29RNTNpcWtVZlVIdkhzV0RBRi9qc1NMSmpKemxY?= =?utf-8?B?SlZTWmllVy96WEZFYlU4SzRra3JDL3BaekFiZExiQXFYR1VyMUNWKzV6V2tB?= =?utf-8?B?akFBK2k4MzYxVEpDaUV4dnpFbEgzMXNhK0pJbU85dDRMazBhWjN2cm5yV25E?= =?utf-8?B?OGV5aUdVK1BhNEZENkNnbEJENFlwUG1IWE1EMUdHODJtVjlTcVJTWUJWVnND?= =?utf-8?B?ZmlqRTZJeFFxVFFyNjk3emNnYWI0QjJmU0tYWW8zVGdweFB2U2hyV3QzcDll?= =?utf-8?B?YXBNRXVSQ0FmZEVZL01pMXFnREhjOThzLzQ4ZkZtRlZMM21tckh5Uk9OMUpx?= =?utf-8?B?VHpTeHMzT1ZKdER2SHNLVTVzSTdQR1BiTTM4TVc4bERxZGNTbVhMZENZcUlw?= =?utf-8?B?dVpLNlF6NGNxbi80Y1c5b1B6dGpyeTlkRE1nZ2pwZ0pKUXFRRkFPNmoxc215?= =?utf-8?B?dzhRclFRRjl6OVRXSisvbmhJWW5ZU2N2TjN0cGt5bm5yWGRlam5oak9hYURm?= =?utf-8?B?UjU0YVFHNHBCQVV5OUpZZVhjL0pFNUxGNlJlejR1SWQ4N1ZhcmpQdEhPdFZD?= =?utf-8?B?YWRyQSszQW9IN3BBdFZCZzlscTFkbGkxNEMvT2tSeTZTYmd6ZjNpVkxwWDdM?= =?utf-8?B?QkxNbzU5L2NzenRNbWh3RnFSR3lJWnNhOHM4eHRkV3E4aWQxVmsrTlBCaHFI?= =?utf-8?B?Ym5hbXpBaU1tL3Q4c045MFZMRFltT2YyZnY4Yzk4dFlPY2Jaa1dBVDVyZUlJ?= =?utf-8?B?RFhubFlYVUU2SXhWQkFOUGJmblhWZi9VWXgydEJTeHRlckREaVFOSGdJUDlw?= =?utf-8?B?TW16eXVRZVpyU0Vtd2JKVTNTTktOU1U2U1ZCRitYdVZzWWdnZ0JTRWc5UVBq?= =?utf-8?B?ZVNsSkF1a0VWMXJEOFVVKzNDME5VS3MzRlNZNEZJYkc1YlFiWU1FenhtQTYx?= =?utf-8?B?TERDWG9tQTFXdkFGQ0xxUFIydTljeitwcGdYSC9TNFBxRUYyUXR5Y0ptNTJi?= =?utf-8?B?cHlJamMyREd6UjgyMGhEU2h5SHVGL1RDSlpOVHNMSkg2a0hlWGoxR2wzdW5W?= =?utf-8?B?cGxrREk1aExhUmFWTE1jSXM1VW9yaTNiWWs3RXRsYjh4TlJxUElielpSblEy?= =?utf-8?B?RnV2NEJQVjNzWHNWRFNvMExLeThrOVMwOE03M1hSN1VrTXpwaE1JOVl0Y2F1?= =?utf-8?B?dzlnbXZ6N2JEZUJqWG5MRUlwSEVIb0hqRlRPNFJTWGtFblZUMk1BSEwwNVZK?= =?utf-8?B?Q1VnS0JoVFZxcGN2d2hWQ3doa3NlNW4yZEFSbGFLOGJ1Kyt4QUVOV1lmdTVM?= =?utf-8?B?WVJFYUFaZEUrRG9aelo2d2w3RjBBbE9VeWJqVkhKV1AveWxVY3IxbEtNOHAw?= =?utf-8?B?VjdNaWFjSzBsUGl3UTREcnpPN2JydVk2WElXQW80Z3pqUDZ1NVM2SjFieDhm?= =?utf-8?B?TVVLb2FUR29QQllPaFRQSDYwTFBQNlIrZHZSUzdtWUYxR3lVdnRhcWdrVDJY?= =?utf-8?B?OHVndzJ5VkVhV1dCOUZJZ0VVWjlBY1lGaGpjcktLUlY4L2xUNndTMFhSeHVD?= =?utf-8?B?M2VhWnB4RWtIUFM2RU43MnRGa3hJK3pVMFEvdGEvYkc4WG1oOGNFM3NtMHgr?= =?utf-8?B?REM5QSt2dEMzUkw0TVZCczVWRHZwakJsVEd1NFlvUDE1aHR6Y00xZjMxM0pE?= =?utf-8?B?MXVlNlE3L1pHRXpzTUQ4L1RobitJMDc0UmttOWdoWGFGd3JFcDZ3UT09?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 133c675d-a8a7-4914-c44b-08de59a0886f X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB4202.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Jan 2026 10:25:38.6380 (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: BBGj7luZOrz6HeYDU0yjS0woIXVAlS/GAHI6Kv2onqCfzthhqLoRuHgcVp4zMqO5iJUbI98SE7p685vwNy//ug== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB7710 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260122_022543_209227_D0C8F506 X-CRM114-Status: GOOD ( 20.29 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 1/21/26 13:03, Jason Gunthorpe wrote: > On Wed, Jan 21, 2026 at 10:03:07AM +0000, Jonathan Cameron wrote: >> On Wed, 21 Jan 2026 08:01:36 +0000 >> "Tian, Kevin" wrote: >> >>> +Dan. I recalled an offline discussion in which he raised concern on >>> having the kernel blindly enable ATS for cxl.cache device instead of >>> creating a knob for admin to configure from userspace (in case >>> security is viewed more important than functionality, upon allowing >>> DMA to read data out of CPU caches)... >>> >> +CC Linux-cxl > A cxl.cache device supporting ATS will automatically enable ATS today > if the kernel option to enable translation is set. > > Even if the device is marked untrusted by the PCI layer (eg an > external port). > > Yes this is effectively a security issue, but it is not really a CXL > specific problem. > > We might perfer to not enable ATS for untrusted devices and then fail to > load drivers for "ats always on" cases. > > Or maybe we can enable one of the ATS security features someday, > though I wonder if those work for CXL.. I raised my concerns about CXL.cache and virtualization at LPC: https://lpc.events/event/19/contributions/2173/attachments/1842/3940/LPC_2025_CXL_CACHE.pdf I expose there some concerns, although I admit some could be due to my twisted understanding of what CXL specs states, but regarding IOMMU/ATS, my view is ATS is not safe enough ... what I guess is a matter of opinion (trusted device based on vendor confirming it is an "official" device not enough for paranoid mode with vendors subjected to governments "agencies" actions/pressures). But this links to what I think Jason points out about ATS security features where the IOMMU hardware can be configured for checking those translated PCIe accesses as well, if the host owner/admin paranoid mind decides so. With CXL cache that is not possible since the route is through a different link and AFAIK, there is no support for something like this by current implementations. I think it could be implemented without impacting the gains from CXL.cache, but that is another story. So, FWIW, I think it should not be enabled by default. Thank you, Alejandro > Jason >