From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.13]) (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 934EF2528FB; Fri, 18 Apr 2025 23:42:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=192.198.163.13 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745019742; cv=fail; b=f0c3YjhiFKg+moASpJTJ3LHSBn2ITKezZSuDoC3071I33WJNnq5j5Oe98JHqewDlXjcoDvAvzR56M6mYlQ5hNj63qSMZxpbYkqOZ9jPEm3MJZQv4QEKnhkczvwx7uqUsqhvXiTGsSaMPheelYBTauz2kjNx+nUxUd47rhQjP2Hc= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745019742; c=relaxed/simple; bh=8LiycUyxH1+p09WIRLVrNtbh3o6OlWfD5JTkCS2gznw=; h=Date:From:To:CC:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=Fvom+Vrhph/hqMPaBMNA3uNBMwv7wRnV4dj/RMP/PgU8Kw2UTSjbRCgFlRfoy3vSan5JVTmmoSXWJmpsaMluMKw7GZ9yPElRNmMXPFyRMpi3vi0GjQbv3R6iFVHPZrg4wBMGjjmvp4h3AL7ky7TCM06LNc/T9Dvndr0sFFxysXI= 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=AEIsdMVz; arc=fail smtp.client-ip=192.198.163.13 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="AEIsdMVz" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1745019741; x=1776555741; h=date:from:to:cc:subject:message-id:references: in-reply-to:mime-version; bh=8LiycUyxH1+p09WIRLVrNtbh3o6OlWfD5JTkCS2gznw=; b=AEIsdMVzW3P+5Iadz094k1YzmDKMw6ZgvEslQyThyJOxzLbl3fwX3pHp 5tTN88FyL+94xUcwO986lMqR3E6DWziFo2ONg6f8xCUBTXPOq9hZ+6Twz e2kNaBYfTDTbRBFWs58bz8QvZGy/RV0bpoE1HuD4KiHbDyARDcbJVT0S8 Huk5ApDf5XZnWserC5QL50oWazCAXB7+kjZSfF0LYMDmdpQxg3Ro2RHYL 98EnNpbVF4veGN9BtBN8np7edk2XfHZwWDli/IUDsGPnDAx0uUrH+t08I dsHJ6KwMWnLjzoTgmB5PxZsIw/mtsWrSvl2UREloc0WhfFPTK/MIsPW9i Q==; X-CSE-ConnectionGUID: agjSNVJfS/i2ealPHXu1tA== X-CSE-MsgGUID: +uYWzUfPSGC1+kyqV+xi+w== X-IronPort-AV: E=McAfee;i="6700,10204,11407"; a="49318335" X-IronPort-AV: E=Sophos;i="6.15,223,1739865600"; d="scan'208";a="49318335" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Apr 2025 16:42:18 -0700 X-CSE-ConnectionGUID: 2nt+oPuCQhKu2kFOChN00g== X-CSE-MsgGUID: BcMYnLfvQ5iXYyfVPBAHbg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,223,1739865600"; d="scan'208";a="131531810" Received: from orsmsx901.amr.corp.intel.com ([10.22.229.23]) by fmviesa008.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Apr 2025 16:41:26 -0700 Received: from ORSMSX902.amr.corp.intel.com (10.22.229.24) by ORSMSX901.amr.corp.intel.com (10.22.229.23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.14; Fri, 18 Apr 2025 16:41:25 -0700 Received: from orsedg603.ED.cps.intel.com (10.7.248.4) 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 15.2.1544.14 via Frontend Transport; Fri, 18 Apr 2025 16:41:25 -0700 Received: from NAM02-DM3-obe.outbound.protection.outlook.com (104.47.56.45) by edgegateway.intel.com (134.134.137.100) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.44; Fri, 18 Apr 2025 16:41:24 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=uONlDKugncRIarRH8hJ9NiVWrOWVc7fqhflDHRUh2ZPsrtlnZIikMIqskcO5EriGEFxmNv0hDOLgxXAiAgAUAK/yKvn5mJm8aqKHxImuEso5EAak3KOjsMbCFleXbepKMsv/68Uw/lg14x296k7IeLvC2WCr96g7TNDjByHXuyzkCIarzTDK2R7oSCEFI1ALVjJXq8jdb2PDUDJJ8xcLPPeO0MkmMGYZCKNfFPLh9uRm8jt6/iVLY4tUOKUvynFoEPUR8Zd2axIhBq7586ohB1o5F8lsNMIy6MCSK4DMZASYFem3IZ/GmA1WFRLlqnhd7vI8o9gOLkLZYacWnjLNnA== 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=Za/cLphzVJ8fkuNwNolWAG3d19FxfyGEenxGIoHpYR8=; b=W2PJDHbYcrU1yxIC9Edvhlu1eWPyGrJCtzh1PtD5wZ4C1EEucLOCB6UHD5rp7yUepa2jI/WTEbyVsqp89ZDRh/CMftU2KgczULDxaxOsrJDBPERC+JLzUr3hkHXrRSAWgkvtHNZyssovj4Rqrpzj47QnAKxqaqYm7XbGR78B09p5cpInwcipVb6J66wQ4ix5um2BuJkbM698SgmBHhNaelYRRJ/7QizgWnZgVM4qIWWYPzQhTv84edb8l9M2ypPLIvskN0Yu33Y3y7legVN8bTN+kwSxIrUYxdvw7XzImK+3TSpmUthPz5YfUxuJznovEWTUs5PBxnzfvKaJy70LyA== 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 PH8PR11MB8107.namprd11.prod.outlook.com (2603:10b6:510:256::6) by SJ0PR11MB5152.namprd11.prod.outlook.com (2603:10b6:a03:2ae::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8655.22; Fri, 18 Apr 2025 23:41:20 +0000 Received: from PH8PR11MB8107.namprd11.prod.outlook.com ([fe80::6b05:74cf:a304:ecd8]) by PH8PR11MB8107.namprd11.prod.outlook.com ([fe80::6b05:74cf:a304:ecd8%4]) with mapi id 15.20.8655.022; Fri, 18 Apr 2025 23:41:20 +0000 Date: Fri, 18 Apr 2025 16:41:17 -0700 From: Dan Williams To: Smita Koralahalli , , CC: Alison Schofield , Vishal Verma , Ira Weiny , Dan Williams , Jonathan Cameron , Yazen Ghannam , Terry Bowman , Smita Koralahalli , Robert Richter Subject: Re: [PATCH] cxl/core/regs.c: Skip Memory Space Enable check for RCD and RCH Ports Message-ID: <6802e31da6854_71fe2946e@dwillia2-xfh.jf.intel.com.notmuch> References: <20250407192734.70631-1-Smita.KoralahalliChannabasappa@amd.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20250407192734.70631-1-Smita.KoralahalliChannabasappa@amd.com> X-ClientProxiedBy: MW4P223CA0019.NAMP223.PROD.OUTLOOK.COM (2603:10b6:303:80::24) To PH8PR11MB8107.namprd11.prod.outlook.com (2603:10b6:510:256::6) Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH8PR11MB8107:EE_|SJ0PR11MB5152:EE_ X-MS-Office365-Filtering-Correlation-Id: 01cfc89d-4f75-4f6a-6cdc-08dd7ed28567 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|366016; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?jPt8NrPAPN8EMbP1CXEyAq+q9PUqmX1H3cM5hymzKy86H9k0VjT3Zn1fT7bK?= =?us-ascii?Q?tInj5t+x2kwKw4e9+iOuoST64BDZzcfNruiYYhMA7JAyRFLjFxrrK+/b7PBO?= =?us-ascii?Q?M8GKpTGazASPDF5/C4BSJ5quNc3tM8/fK9SATY26R7rEempdh1/zS0z18iCI?= =?us-ascii?Q?KOXCXz/Ej3HGnQ0CZ1/T1GHoQwvGh0kTkNgs5RRfIvGJldRZmQJOd77H774z?= =?us-ascii?Q?W4Ot+3xfSV7GxEniiBSQzhhbC074j7G26ZD882AAsf6D0fP2RtjavCcC/xnY?= =?us-ascii?Q?rtrdkja+E/d8QgPuhzbsatJqHB+nMhtNNVHViWp1u2hmHnmN4n+LH7+/sPdg?= =?us-ascii?Q?U2gCSUTr8M0M2Z1x2tQGS6Io/zyVr2simwqGZ2C5W0qZRNhhb8AL0fPWk17t?= =?us-ascii?Q?e5wcjAjhceP8oopYgIb4VX9jqqu0dBiZrD4MSLrY0Su8GX7v3c+BO8zXXgef?= =?us-ascii?Q?uzzZKY5JpflEoLg7NzH5yXrInURW2NGu7jZPOVg71ZHfHIPV9cZQZnjmo7OP?= =?us-ascii?Q?QLVLDAajMOwLTaDaY1VJQhHeKTRVd/Hy9qT8L2jy6i8uPLZVMro8r67Jlskr?= =?us-ascii?Q?5VnMrBTPKibZtQLHQ1dGx4U5CiYCuv9HA00dHkKgsh9eqN64vAhckAc09THO?= =?us-ascii?Q?dsp/IHBnWCY5vQPw8Wq5vICiwnlmOQMV7oDt+WI6P59NxjBr1hYxxwWAT4dd?= =?us-ascii?Q?29VynsqQxteYhDGGXg9CLg86Lebmacap01psjLjIzqdBZTw08W6dl74HZdUR?= =?us-ascii?Q?WLx09UQPRbu+Tcn3hKYN4KFVjyYThwoJedcdXzhpYY5MXwwRzNY+7I9UTF78?= =?us-ascii?Q?K1Qiaw6infK+xZTAElpqDPSnu4gYwv7EMx4NAk/6g//tiG7dqRXl3K8aK/FT?= =?us-ascii?Q?LX21EDEppKL6QZztqq+ZT2gxcCAsw2umIW7qCZDP2kkFD5Re2wu1pfzRB32R?= =?us-ascii?Q?OnCgmDLbd229cVhHwbVck8r1laXwkzm38XWREB0U2aW5ZEIjmrO+hdycr1+O?= =?us-ascii?Q?WeNqM2MJecoWjGVbtTAzh8L0yuPGX6SHrOuD7R87O5sx1vOGUAXQb8N3NhjD?= =?us-ascii?Q?u7m8HzxdlM51wWeWB72JCIRu/PUPjpocFdOoLBcoVq0y2jmPplewM5kZOXjY?= =?us-ascii?Q?TQcmmXz7wZgJJezmgPiP7PWNLyGbGDrc+y0yGSE/EntVHdsAH20G+Eu8QdzA?= =?us-ascii?Q?xrXElrhswtMKukCqiZJSSQ2N3DWtFeL7QF9snqe3Sp8Mg8Mn4QDvlEE5VKP2?= =?us-ascii?Q?8i8+yh/2V/d9gy/R6MhyTSUiZZboXH8yGQr5mMDrRh4fHteX9y/zf8Ko5tOC?= =?us-ascii?Q?YqMck8hNjqOZQMMtxkwfvRvs4AmaEQGvE71gg6fzvzI+EUk1GblRpgVnNjzA?= =?us-ascii?Q?yvYvUNBI5idbnQsgYmBkeuZyaVD/0QWOOQz5a3+f4eWOnBj+CMM6BQKJEzJ/?= =?us-ascii?Q?hJ0WO6irC2M=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PH8PR11MB8107.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(376014)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?89H2NUpbF8BBvoX0reAKjTsx+crO859JB/jw7EBEPrpN6HDPT49NmqlJG8sm?= =?us-ascii?Q?QhUYsFHS/nlVzDly1Ejs0bHgzqxzyAuNnCM6ti5hPwqkTawNLfXo7YBn7I+b?= =?us-ascii?Q?KsqqQeDu09UPQTFYLxXsmhQi7CXwNgxXzA1eNtuOIh2YcEEYQZqu0uvzoa2j?= =?us-ascii?Q?ulmUc0eTooT3UwHEkUhlXvDcTtVrJPt+Da0SO+CDQR0lG/gbew2tny2TjbJ+?= =?us-ascii?Q?Ogjq9J+sJNOftvM7tpeVIpJm7Xh5XZ+i45KSNVoOzzEwXugAHWRy4Ot8GPn2?= =?us-ascii?Q?1jvj4sPgcZVdgMBzpJGTZLA+4MXC5NFnXeNgB/gpZIpPKePA/Jge8zrgDdnY?= =?us-ascii?Q?PpT3bkdrW0mtgcvEB7Cw2p4rX9if8mRlHE3civUN/c3r5UFLYUYOow3oKIV4?= =?us-ascii?Q?W+Ads5vZPZ+deu2xXhtUiyhpJsxbUuWpp9X8rKBFMIQ/LaF9lhETpoonfZmz?= =?us-ascii?Q?WnCGA/8w0uXWrgW7OYnZ9q+YswywucIwvG58SNvwYJj7oWYTlR1gXY5+fnEU?= =?us-ascii?Q?d9y490i5eNOYGcz7Iuy+DFvjHVU5B0nGSqV79TYFGT4WvHqf7AVcwnYRv80H?= =?us-ascii?Q?uAaq0YHs+LPeh2hiqQDc59+yQ5yL4sX7gNNynYqdJPQpqLoQdTBbuo0gYwWz?= =?us-ascii?Q?q95UQJsXpXBUsDr3h3n2lC47GGxDW9zBGesQQUncxlBWSKJSsToAIJQyoj+R?= =?us-ascii?Q?ODgISoJgcIl6E4H/6mZ8bD8N82Ov8hS7e9AEjM7OUjNtxVzLRTpCgh5MNtsC?= =?us-ascii?Q?PJHUd30eFaG0YLlAISerHbgGz/3UrPL4XuIOyu+FSY8WRQfIwqWSJvdSazrv?= =?us-ascii?Q?edMakjnLJhYG6teDHmOmyR9RxgJbsb3tsfGoH59zYI5VRt1VKw7d8XMXEqRx?= =?us-ascii?Q?1YOCRBiRPpmbWCA+3TwYcuIt62Sg+KuX4X+ArMRSicI4bk9UEcE7lmnwaO26?= =?us-ascii?Q?854uBfCkJlr/K+Ef4/Fd10Tv0QfG7vTY7phlxmQuX6EerSBK9uyA4DLirbgD?= =?us-ascii?Q?IerwemV6gByUrgRjICzlsSDIduQyeGlvA+JGbvgDQokkPdQswM6VohG5XzQH?= =?us-ascii?Q?cwLYa/OA5c50ssH6dzuXhrYdy/wQiTo0nwIdZQAy0UlbQE1iXzY3VBPJipzS?= =?us-ascii?Q?gaTQDUf9xYt/jkoQmsUAf9/vlU5EdSD1xYK4Mp71kCE/SEiChSBj4/U7TIfk?= =?us-ascii?Q?GbN5f0VCxVurDOWf8y62m+BccX6U2UO9Q7GgTtL7H5T+jDrYW7vQG/R8KznW?= =?us-ascii?Q?ioHCzqC9kPONq3dR6ALk78qRex15R4dPR5d87TMQFENReYMEUvxpQKVMPeQ3?= =?us-ascii?Q?DiurkjifnuXAOaUOFBLQeLOL4cN72woOCaKAu7E5jUyg2MoNBrS3Rr6wLCWp?= =?us-ascii?Q?bAIDRAJyOgtwxSSU6rA5cJr4/MjdXr5qTg8CTbfPi5KAZA7NClHMRHZ6pcK4?= =?us-ascii?Q?pU/pTiw/PSvYXjB0qJSokC/mITmsZQkMxOHZbyGoUfyB+dRssoDeHlqYIajP?= =?us-ascii?Q?05wfHnL6iw3y/Y40E7HejFgDvkZkb9PlFWKVCPDza1JAjQkCqoEaB0L6DxQo?= =?us-ascii?Q?JEAZhER5ipL63Bw/qfibwXUD8B3A3Tj2TgUoLCHRBCXI/lVtPcIrOt61WStw?= =?us-ascii?Q?vQ=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: 01cfc89d-4f75-4f6a-6cdc-08dd7ed28567 X-MS-Exchange-CrossTenant-AuthSource: PH8PR11MB8107.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Apr 2025 23:41:20.4504 (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: zPohr67rtj8xF/WDBpxpZ8eR+/c81IMuklmF4ZoQKUq3V+jp3fLzjVxTvSKZX3f0ygXpZL8zas/ky6t0LX4I6RFEe24adlVuNihXJZ59m7Y= X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR11MB5152 X-OriginatorOrg: intel.com Smita Koralahalli wrote: > According to CXL r3.2 section 8.2.1.2, the PCI_COMMAND register fields, > including Memory Space Enable bit, have no effect on the behavior of an > RCD Upstream Port. Retaining this check may incorrectly cause > cxl_pci_probe() to fail on a valid RCD upstream Port. > > While the specification is explicit only for RCD Upstream Ports, this > check is solely for accessing the RCRB, which is always mapped through > memory space. Therefore, its safe to remove the check entirely. In > practice, firmware reliably enables the Memory Space Enable bit for > RCH Downstream Ports and no failures have been observed. > > Removing the check simplifies the code and avoids unnecessary > special-casing, while relying on BIOS/firmware to configure devices > correctly. Moreover, any failures due to inaccessible RCRB regions > will still be caught either in __rcrb_to_component() or while > parsing the component register block. > > The following failure was observed in dmesg when the check was present: > cxl_pci 0000:7f:00.0: No component registers (-6) > > Fixes: d5b1a27143cb ("cxl/acpi: Extract component registers of restricted hosts from RCRB") I expect this should also be: Cc: I think the stable team always attempts to backport CXL Fixes: that reference older kernels, but always good to include that to make it explicit.