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Thu, 11 Dec 2025 02:13:02 +0000 Date: Thu, 11 Dec 2025 10:10:33 +0800 From: Yan Zhao To: "Edgecombe, Rick P" CC: "sagis@google.com" , "Du, Fan" , "Li, Xiaoyao" , "quic_eberman@quicinc.com" , "Hansen, Dave" , "david@redhat.com" , "thomas.lendacky@amd.com" , "tabba@google.com" , "vbabka@suse.cz" , "kvm@vger.kernel.org" , "michael.roth@amd.com" , "seanjc@google.com" , "Weiny, Ira" , "pbonzini@redhat.com" , "binbin.wu@linux.intel.com" , "ackerleytng@google.com" , "linux-kernel@vger.kernel.org" , "Yamahata, Isaku" , "Peng, Chao P" , "kas@kernel.org" , "Annapurve, Vishal" , "Miao, Jun" , "zhiquan1.li@intel.com" , "x86@kernel.org" , "pgonda@google.com" Subject: Re: [RFC PATCH v2 10/23] KVM: TDX: Enable huge page splitting under write kvm->mmu_lock Message-ID: Reply-To: Yan Zhao References: <20250807093950.4395-1-yan.y.zhao@intel.com> <20250807094333.4579-1-yan.y.zhao@intel.com> <5b9c454946a5fb6782c1245001439620f04932b3.camel@intel.com> <2b714bb6e547e2505a83c97fdad79e5dda687d05.camel@intel.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?/13WdzsRS9orKbiUk9Zlv22Gvb1FMN/DAKLmHz5GYFVe5Pm9pgNy+aIofFHk?= =?us-ascii?Q?TsE6jXyuABfQ8ABcL9/k5SxLKYVeUQ4lz2thlBjg/Y+hojetJgR2jcXrv20s?= =?us-ascii?Q?aVA4UOkkjD8vE35xgMBICE+wensvI3LIjCV21EuI1sBjbMkzTms94h2A/coK?= =?us-ascii?Q?a61qm+WhuSUWuV1uf4ljjiWWMePOheTwQ4J30gJNmSsL27SnV1xAUdvjhX6u?= =?us-ascii?Q?YMYzlYbs4WTTzyIGTu+0ybawFcJBbDYqFVI+VZ0/hp5OziiosiaOQR90jckQ?= =?us-ascii?Q?tSdJV9+FvpxHlkXhriXgGLtl96VBHgW8Gn6KmZqFupLyn8ndt2+cR8nh2AdE?= =?us-ascii?Q?Cw0slpRSaifdkgGp1NgSuL7q2m92t/Jrj+fG/JEc4gzdYszXlnPsDlRRlwgV?= =?us-ascii?Q?RHPSiFFJy5fAhOF9UjsWpTHzyxLoELwD+mZd/HXD5qyjTax4vD5p9akk2YXb?= =?us-ascii?Q?8nYpKmcLZHj69hEaAFKsHKaOkm3zcdiTd935bOOtXO/RGKV3rExpx+mNbqvA?= =?us-ascii?Q?V7U7R/iyPFzbce9eMtgUicCZTLP+d2fW2dArl7oXDQ99sD13BNFRKcZd7Ztq?= =?us-ascii?Q?A8MQKgI6U747MlM6tNlQyqWfObNVdvczNjK2sC3Sisjiqqe9URjfH4nc/3Si?= =?us-ascii?Q?Exrjf52XMvg9Ig/rvkYHTLnm5C3JDAWZTNBudcvk420s2o1VzZJ5RJ6b8orZ?= =?us-ascii?Q?he5jItiXJY8zi+4tuMqtlKGETPj61/wecifTGpsegg9Q4GCANhxw8ojqZr3B?= =?us-ascii?Q?kSCGZ1eG5Sv5kbXia/pcloCjE2Mn73gmmK7OT3o+sDHLf0WEK47hVblQPJ1/?= =?us-ascii?Q?drkDTMK9+dm/mRA6EwX7amE1PoaMD3jBfPr0mEEkkBHJmNB9RgX0dRkJpecN?= =?us-ascii?Q?Jn+Gpi8/i0cj9uFeTeEODgfneUDCSQl0xibPthtNlH1nKvuUcVdDNthqubdF?= =?us-ascii?Q?CWSadP+LQQrwYz76SSlnMRQYhCepDB5yuFXv/XCmbNKvkZ7cZX9+hcGZBPPP?= =?us-ascii?Q?iVMzK/FgbpReEFfT1JAVS4fyvUCtnKuhJNVt6F9lJdG+WSIr+i9Ohe8ogFCx?= =?us-ascii?Q?nrlD2OKl/Y/d+Hl/pyW28YjXPcYuAxRpzl6Oy1MSN9KHtrN2zDrr36rQ3d7E?= =?us-ascii?Q?aXKw1uppig3O7nQ0yNMkiymVoiqhpswY/RhalCae3XMg2TKH9TmfnOEdeuai?= =?us-ascii?Q?xT8ogbDVqTgGISW+jIWCSp6rvcSsEeiI1QEE1QJIfwl0uiJca2cEHAUz9AH4?= =?us-ascii?Q?mXq66IChUm/sVmMjDotkJsCSE5ckZr7HIv60mujt8deSkMFtcj3plDfibPIS?= =?us-ascii?Q?gRyqBk+wali7RPJviYBt/UyqoKG02oVH0FBnZW/Hz1YgbcpnKxDY+Tgou77b?= =?us-ascii?Q?no3ig83PY+9L1lRchfCnJua62/0e/GZmbK6Sso7/pqSx7aXiZgLqHpOm8A+Z?= =?us-ascii?Q?lNbOX9pIP970UKt7wT2CtZ080Jmsz/VoQ62AhGUQxwnPyAfmdhCNxJRWWf+P?= =?us-ascii?Q?UouImA3vGEWLaUyH5RmnpLMDB0CxLS+JcHia4yHKF4BTtoQa8mlQof/BPTK5?= =?us-ascii?Q?lgrEjaOT8O/u2DqptvDKkZ/+HNtPsPeWiWt91NC/?= X-MS-Exchange-CrossTenant-Network-Message-Id: cf007144-ebea-4cff-ebf5-08de385acfd3 X-MS-Exchange-CrossTenant-AuthSource: DS7PR11MB5966.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Dec 2025 02:13:01.9987 (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: 9mUzIzHnEKAplfeqnywqfNf6fRiE5TbnHUnrM1On47WtVxHCOhvUv+iP84+RL0RDgGqrF55iXo8IwScxgrlQBQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR11MB7564 X-OriginatorOrg: intel.com On Thu, Dec 11, 2025 at 03:49:26AM +0800, Edgecombe, Rick P wrote: > On Wed, 2025-12-10 at 11:16 -0600, Sagi Shahar wrote: > > From what I saw this is not just a > > theoretical race but happens every time I try to boot a VM I don't think we mentioned that the retry for TDX_INTERRUPTED_RESTARTABLE is theoretical, did we? :) On my SPR, to boot a VM with 8 vCPUs 8 GB memory, on average there are 271.4 demotes, with 1.1 retry for TDX_INTERRUPTED_RESTARTABLE. # | demote cnt | retry cnt (for TDX_INTERRUPTED_RESTARTABLE) --------|------------|---------- 1 | 271 | 2 2 | 273 | 0 3 | 271 | 1 4 | 270 | 2 5 | 271 | 3 6 | 271 | 0 7 | 274 | 0 8 | 270 | 0 9 | 271 | 2 10 | 272 | 0 > Oh, interesting. > > > , even for a > > small VM with 4 VCPUs and 8GB of memory. > > It probably more matters what else is happening on the system to cause a host > interrupt. Agreed.