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Mon, 19 May 2025 04:04:05 +0000 Date: Mon, 19 May 2025 12:01:54 +0800 From: Yan Zhao To: "Edgecombe, Rick P" CC: "kvm@vger.kernel.org" , "Li, Xiaoyao" , "quic_eberman@quicinc.com" , "Hansen, Dave" , "david@redhat.com" , "Li, Zhiquan1" , "tabba@google.com" , "vbabka@suse.cz" , "thomas.lendacky@amd.com" , "michael.roth@amd.com" , "seanjc@google.com" , "Weiny, Ira" , "linux-kernel@vger.kernel.org" , "pbonzini@redhat.com" , "ackerleytng@google.com" , "Yamahata, Isaku" , "binbin.wu@linux.intel.com" , "Peng, Chao P" , "Du, Fan" , "Annapurve, Vishal" , "jroedel@suse.de" , "Miao, Jun" , "Shutemov, Kirill" , "pgonda@google.com" , "x86@kernel.org" Subject: Re: [RFC PATCH 14/21] KVM: x86/tdp_mmu: Invoke split_external_spt hook with exclusive mmu_lock Message-ID: Reply-To: Yan Zhao References: <20250424030033.32635-1-yan.y.zhao@intel.com> <20250424030744.435-1-yan.y.zhao@intel.com> <11de62c95f7866fcecdba4c2d9462c77bab3bf83.camel@intel.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <11de62c95f7866fcecdba4c2d9462c77bab3bf83.camel@intel.com> X-ClientProxiedBy: SI1PR02CA0033.apcprd02.prod.outlook.com (2603:1096:4:1f6::14) To DS7PR11MB5966.namprd11.prod.outlook.com (2603:10b6:8:71::6) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR11MB5966:EE_|DS0PR11MB7532:EE_ X-MS-Office365-Filtering-Correlation-Id: 764b78df-1c0f-4d9e-d6f6-08dd968a3295 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|7416014|376014|1800799024|366016; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?0eJv9bExz6hv/qOyNXqxcOlna1MMkL1aduObdvzaFvkocj/l3YkjavWd9lvB?= =?us-ascii?Q?QIqXLbQ6qS3wcNPEsHdLFUmxAJsRUjaNjIoxrRZjiox1WogwabPoIWT2jCbb?= =?us-ascii?Q?rUyp/cEEo8n908BjCk1yls0NFRrYnVNauLsaXSf+StZKJUJYe/hgmaxa62ix?= =?us-ascii?Q?6yk4GUkjNalzwN7gydkyTfqGTRpBuVxvsbuQP0OxrC1Qt2qjBGYmKNDshEY2?= =?us-ascii?Q?a8CZ37cb/TzzSCDEggiMOqqT3a+C+HZX0WYi58JMwn7yqnyuIr/uV6gqup6Y?= =?us-ascii?Q?+WhnbKa3JooAGZu0DGfPRlZ1zxe2NYeNbONfAblk13FHHh437McrrN2dHVXt?= =?us-ascii?Q?nOU6LzYwUZMavDxHcw5tGm/suMB16IZKH7nkQJBy2ruDmPLgjrEv7EcauZ+H?= =?us-ascii?Q?UoqgWfFuQbaZHxk6keSz/pl+qL1qERYk7wd2GJ0l4QkBaTxpElGBnJRvM0SZ?= =?us-ascii?Q?ys5BnZPr8cOUOPrHewN1ivPOf2BddEr7jphWoaye+yOs6e4xFtAeeJf9HmBb?= =?us-ascii?Q?dSoGeexqVkJ2RWNCb+qD9rVRucfsUYXGv4uJpqV+HOnT/COfPOPpdXQlsxZu?= =?us-ascii?Q?caeti/1eY2IhmXePCzCrACf/xj007wArihtnNDkhIN8M/oWN9BAelONXGNMi?= =?us-ascii?Q?E4bfycA2eEgT93uP5x1hmm2a/uNOuxHPvpuKyBnkYTWYeDoSLPhvuENpBxwE?= =?us-ascii?Q?AWLwoPCJwWA3lp96k6Zpygym5oPdjps+WwQRqN3aLT37IIwhIWi2i1TD6NJ8?= =?us-ascii?Q?x7dJarXgSU5+MtvjsKk/DqJbPpuiI9pE82kAlfX3v5BYOmYscwtwt3qFpin6?= =?us-ascii?Q?Td/dI/zLk1z8FI2YWJaL7T6RJBKJ2UTC2mchGq3SkKstmfPlSaNN1XJcDsb1?= =?us-ascii?Q?7o/5obMbv7vfIbZRxrHJLD6DSlRkWjAC1qNhHNSYm7sxG9U6L0O9rDden7KZ?= =?us-ascii?Q?hQGEZOPARb4+9sHp92UV2ZJ5ODv2cuAyD8I2Cf+838fJpK5L3LG0zA6FW9v/?= =?us-ascii?Q?CpWchQTJk4RjTL2tShx5SlXqmQDybUdSTO7UA8+Uc/rjRoMOMgFtf3soJhWo?= =?us-ascii?Q?7mJVrjb5j60DD8xyvw05jt5eUnnQCTWVJwbrSUF0mkFQz8DIcKAhDKoUNMiR?= =?us-ascii?Q?g1HvU4Y+tQBOXJVZVYtgX1ta0O3y7+RHKFwTWWBxQNYCkf2Q7o52VPWLHp/1?= =?us-ascii?Q?VTbMPn0coO38HreQQSqP2HcOE86WrBRwUvkQ+2GSZwuG2IMmH+O0EiSIbOZn?= =?us-ascii?Q?iM8++ZmokbMWTVaRAD/ZrvrTlRRE57+KfmPd175orr4vuWIoTym/53af5hhQ?= =?us-ascii?Q?BFOVqptkeL5k91d/Mif9Altp/HOu+O1L7TWKpGZWTC9OTHZOkgKFZo17r4jq?= =?us-ascii?Q?wuRcendR/KPzVR4Diz7ZUBeSrSaZRAjN9ReVJiYX5g7iH93Fuulw5evvHPxt?= =?us-ascii?Q?cBNA7pEvEg6qrn+AWWWtSr+ChIX8ylednhS7CwSvezypxLtJ8xOv6Dz1pZD1?= =?us-ascii?Q?PDxiK4uRlQQ90h5vNZG3aj/3LmdptnzQBobxQbz2kRUIE1RKdTLiLlqf3APb?= =?us-ascii?Q?3oNzDYbzkEWGBkIjQ11MPG8MndSUCSldOZwiDZTQ?= X-MS-Exchange-CrossTenant-Network-Message-Id: 764b78df-1c0f-4d9e-d6f6-08dd968a3295 X-MS-Exchange-CrossTenant-AuthSource: DS7PR11MB5966.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 May 2025 04:04:05.6072 (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: XaXVmQN3VcIPPBZZ220AOF1gTFgwxycahk2Gx15EDiNhuI+oGXwsK0d9RVEVdbF4ovOOghUMRcBQfOX52Lm2JQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR11MB7532 X-OriginatorOrg: intel.com On Sat, May 17, 2025 at 06:11:59AM +0800, Edgecombe, Rick P wrote: > On Fri, 2025-05-16 at 17:17 +0800, Yan Zhao wrote: > > > Shouldn't this BUG_ON be handled in the split_external_spt implementation? I > > > don't think we need another one. > > Ok. But kvm_x86_split_external_spt() is not for TDX only. > > Is it good for KVM MMU core to rely on each implementation to trigger BUG_ON? > > It effectively is for TDX only. At least for the foreseeable future. The naming > basically means that people don't have to see "TDX" everywhere when they look in > the MMU code. Hmm, another reason to add the BUG_ON is to align it with remove_external_spte(). There's also a KVM_BUG_ON() following the remove_external_spte hook. I interpret this as error handling in the KVM MMU core, which returns "void", so issuing BUG_ON if ret != 0.