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Sun, 28 Sep 2025 01:42:03 +0000 Date: Sun, 28 Sep 2025 09:40:54 +0800 From: Yan Zhao To: "Edgecombe, Rick P" CC: "Gao, Chao" , "seanjc@google.com" , "Huang, Kai" , "kas@kernel.org" , "Annapurve, Vishal" , "bp@alien8.de" , "linux-kernel@vger.kernel.org" , "mingo@redhat.com" , "dave.hansen@linux.intel.com" , "kvm@vger.kernel.org" , "linux-coco@lists.linux.dev" , "Yamahata, Isaku" , "pbonzini@redhat.com" , "tglx@linutronix.de" , "x86@kernel.org" Subject: Re: [PATCH v3 12/16] x86/virt/tdx: Add helpers to allow for pre-allocating pages Message-ID: Reply-To: Yan Zhao References: <20250918232224.2202592-1-rick.p.edgecombe@intel.com> <20250918232224.2202592-13-rick.p.edgecombe@intel.com> Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-ClientProxiedBy: KL1PR01CA0105.apcprd01.prod.exchangelabs.com (2603:1096:820:3::21) To DS7PR11MB5966.namprd11.prod.outlook.com (2603:10b6:8:71::6) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR11MB5966:EE_|PH8PR11MB7093:EE_ X-MS-Office365-Filtering-Correlation-Id: 6896c747-bb01-4f8b-30b6-08ddfe3039a3 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|366016|1800799024|7416014|376014; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?iso-8859-1?Q?6abvIFN6Kk/7AJUqtkyVwl1uYOjSu6qNylVxkdm27fJuE7so3cbZ5y4cF3?= =?iso-8859-1?Q?TBUfowkGtcmb4oHQYXeDzxNGJtP0uHVdX2vX0my7hjTjhlj4JuEclBym5V?= =?iso-8859-1?Q?y9G5vpc3GPDqLoqfzRRGf/OphVm6pp8Fz+H+W9aP0mkbuf0aTzjNvnxCFN?= =?iso-8859-1?Q?5a5Cz6WkzsoNE0tp/ZrF7it/KxYalw/U2f2cIawUfpPHUOb6P9XoAUFsN5?= =?iso-8859-1?Q?/+Uq3T+Bg+PgozRhkutzgSrrgGOwpx2ACkn3Agyd3RuR8cktc09LCJsbhW?= =?iso-8859-1?Q?sZ1EtD4V4iCEoSL9QILl1ZW69mJr/QhtPuyngpDkI6kdS2YOkHJ85X1uB3?= =?iso-8859-1?Q?EfvdnVKLYrrhjHIDZztg2AOC30eoNmkOcwvL5XOOJKKTWbc5EghNrEaCZy?= =?iso-8859-1?Q?ZTcWcu0JkjYeajCo158XI2QzU5ozeCzV6RurCKYmrGDcmzLB3FgVlHpfRo?= =?iso-8859-1?Q?HTacNMzruLRouRf5gGS0HC7rf/DXW5BGfoH/o8pZoGCgExFwtoK13l+ynX?= =?iso-8859-1?Q?IhFTbT7ogJ1BxnylfePur7IoINBKmNQWfQTA8KzGLXkW7csefATEQS9/i9?= =?iso-8859-1?Q?pf6Wb5Shf4uOWPXU/cuCt1mbd0XdktrLp6mSXzxcWmkcGxlY1JiAGuyhla?= =?iso-8859-1?Q?cDuRMOCXG2PJzY8HobcObO7kSoqLSksf2PhNFWwS2j2rdqsijwX9OijuIh?= =?iso-8859-1?Q?AO9QW7i8XkBepjkSN+Ogx/FsZN4y3dPwKDDfyNttppm6n1JxiGP6w6tHPz?= =?iso-8859-1?Q?57670nookKOwcLflMdhMLXgUM3VHENQGyqcZoYP4P0/X/mSrSaJuOvydNn?= =?iso-8859-1?Q?DRPyPBqZ1lSDYG/qngmCIsfvSFLQ7aL9AHKqOPOBPfqubddvwih67v+2gw?= =?iso-8859-1?Q?ZXFWg9xbkEQxiR8dmhehLFyORRZpq2ogRneG9r/AL8T8dQ5fNc5UWX6URG?= =?iso-8859-1?Q?x0DZSqG2YORfZV0k/teG1/pd086CVn4kHJDVke++p+o8Dmqx2BQaCVHgMh?= =?iso-8859-1?Q?5IVexcIZ7JM493nTl1+kc4Lz3dUG4qOdrZmnamFSVlO3ur4pudLj9hr3Gl?= =?iso-8859-1?Q?P4HzgTOBxoAtOPYq0DvAqTd40GMj3vJHC7ESM5Zz+D5B4usuNVgM/KU1nW?= =?iso-8859-1?Q?W3vFQ46/GJ/lIzjTJkhY4fEN7+JkTkkLagT+y/5ZkWB+JQ7NPf4LEkgceI?= =?iso-8859-1?Q?s/XZWk+97ptt7fCOZBa8aa77XD+OhChPhmGgMeKu3OK6y8boYZfaZ8z4oC?= =?iso-8859-1?Q?OS723ao6b7ML3V71jkXCRXkSWFzJ6iA+JCCn/9QiU8lo9u4dnfkPE+Dx8U?= =?iso-8859-1?Q?pveApFHf+tZnSoFB2E+5k8cusa8CJYbiXwdUIKSXeQmz143rGKq0EVHMlc?= =?iso-8859-1?Q?s+n3IHZN77V8s9nCY7zr+31DGUgB47JoKR0vgEgPhwCc1O0doHSWHOlnQg?= =?iso-8859-1?Q?m9G6Rak+F86Vnwpthr1A2CAPcQv6dpPLK82n62CHTUOdz55wiFDGk7iVxB?= =?iso-8859-1?Q?OhPkJWJ7ut2ABsox1U59Dra8VzkDeg1vmQE0PBHsJQge8jTWlQa7CXs3r2?= =?iso-8859-1?Q?mhMG2fQSI06BP415L791AnIjyxesPolSzqWIuSj2vry4SloqKAAMLl7JuV?= =?iso-8859-1?Q?obC6gFrJaS3i0lRvbxlc7oeT8RhNrk3b7d?= X-MS-Exchange-CrossTenant-Network-Message-Id: 6896c747-bb01-4f8b-30b6-08ddfe3039a3 X-MS-Exchange-CrossTenant-AuthSource: DS7PR11MB5966.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Sep 2025 01:42:03.6530 (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: snDuhjcQNCTiHU2tPpOlWqFF58cb6iAhqzzYdb9OvhvVz6bkL6ro22Ofiovp2DxKYeUvfGIMtD2OMf7O052AMg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR11MB7093 X-OriginatorOrg: intel.com On Sat, Sep 27, 2025 at 06:05:12AM +0800, Edgecombe, Rick P wrote: > On Fri, 2025-09-26 at 09:44 +0800, Yan Zhao wrote: > > > - return kvm_mmu_topup_memory_cache(&tdx- > > > >mmu_external_spt_cache, > > > -   PT64_ROOT_MAX_LEVEL); > > > + /* External page tables */ > > > + min_fault_cache_size = PT64_ROOT_MAX_LEVEL; > > > > min_fault_cache_size = PT64_ROOT_MAX_LEVEL - 1? > > We don't need to allocate page for the root page. > > Why change it in this patch? The previous size determined by TDP MMU core was just unnecessarily 1 more than required (I guess it's due to historical reasons). But since now the size is determined by TDX itself, I think it can be accurate. > > > + /* Dynamic PAMT pages (if enabled) */ > > > + min_fault_cache_size += tdx_dpamt_entry_pages() * > > > PT64_ROOT_MAX_LEVEL; > > > + > > What about commenting that it's > > tdx_dpamt_entry_pages() * ((PT64_ROOT_MAX_LEVEL - 1) + 1) ? > > i.e., > > (PT64_ROOT_MAX_LEVEL  - 1) for page table pages, and 1 for guest > > private page. > > Yes the comment could be improved. I'll enhance it. Thanks.