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Tue, 14 Apr 2026 11:21:09 +0000 Date: Tue, 14 Apr 2026 19:20:54 +0800 From: Chao Gao To: "Edgecombe, Rick P" CC: "kvm@vger.kernel.org" , "linux-coco@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "Li, Xiaoyao" , "Huang, Kai" , "Zhao, Yan Y" , "dave.hansen@linux.intel.com" , "kas@kernel.org" , "seanjc@google.com" , "binbin.wu@linux.intel.com" , "pbonzini@redhat.com" , "Chatre, Reinette" , "Verma, Vishal L" , "nik.borisov@suse.com" , "mingo@redhat.com" , "Weiny, Ira" , "tony.lindgren@linux.intel.com" , "Annapurve, Vishal" , "sagis@google.com" , "hpa@zytor.com" , "tglx@kernel.org" , "paulmck@kernel.org" , "bp@alien8.de" , "yilun.xu@linux.intel.com" , "dan.j.williams@intel.com" , "x86@kernel.org" Subject: Re: [PATCH v7 06/22] coco/tdx-host: Expose P-SEAMLDR information via sysfs Message-ID: References: <20260331124214.117808-1-chao.gao@intel.com> <20260331124214.117808-7-chao.gao@intel.com> Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-ClientProxiedBy: SI1PR02CA0054.apcprd02.prod.outlook.com (2603:1096:4:1f5::13) To CH3PR11MB8660.namprd11.prod.outlook.com (2603:10b6:610:1ce::13) Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR11MB8660:EE_|CH3PR11MB7675:EE_ X-MS-Office365-Filtering-Correlation-Id: 4ccf4ad4-7dc7-4814-f68f-08de9a17ed39 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|376014|7416014|366016|56012099003|22082099003|18002099003; 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Expose necessary information to facilitate this decision. Two >> values are needed: >> >> - P-SEAMLDR version: for compatibility checks between TDX module and >>      P-SEAMLDR >> - num_remaining_updates: indicates how many updates can be performed > >Can you explain how all of these overlap? > - TDX module supports module update > - SEAMLDR supports NUM_REMAINING_UPDATES info > - SEAMLDR supports VERSION info > >If the TDX module supports module update, do we know the SEAMLDR supports this >other stuff somehow? It might be worth a comment the reasoning. VERSION and NUM_REMAINING_UPDATES are always available for any P-SEAMLDR. They don't depend on TDX module's update support. > >> >> Expose them as tdx-host device attributes. Make seamldr attributes >> visible only when the update feature is supported, as that's their sole >> purpose. >> >> Unconditional exposure is also problematic because reading them >> triggers P-SEAMLDR calls that break KVM on CPUs with a specific erratum >> (to be enumerated and handled in a later patch). > >Since this is later handled with the errata check, what is the point being made >here? I will drop it. Dave also questioned mentioning the erratum here.