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Sat, 8 Feb 2025 02:38:33 +0000 Date: Sat, 8 Feb 2025 10:37:25 +0800 From: Yan Zhao To: Sean Christopherson CC: , , , Subject: Re: [PATCH 3/4] KVM: x86/mmu: Make sure pfn is not changed for spurious fault Message-ID: Reply-To: Yan Zhao References: <20250207030640.1585-1-yan.y.zhao@intel.com> <20250207030900.1808-1-yan.y.zhao@intel.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: SI1PR02CA0060.apcprd02.prod.outlook.com (2603:1096:4:1f5::17) 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_|CY8PR11MB7337:EE_ X-MS-Office365-Filtering-Correlation-Id: 0ddee527-f19e-4fad-5700-08dd47e9ae2b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|1800799024; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?lh6PEyx6K8ABor9WtLYxi4bj4wXVTPVbaqBkweWeneN5U58foRJ/IUW6NwL6?= =?us-ascii?Q?O1E00JcnFyX507pxbjFXdv7v3S9foXobCuTqS+K+xb4H/kLvDgLdWMTW5FFm?= =?us-ascii?Q?hPjY+hx7lOhuimdG/elrWWWTexEZGqpntygQg4seG2YykKphAi+sVso8WeAT?= =?us-ascii?Q?bJzbMjIx0osKHccdrxetNKq7jmqOXWXOROKdluLTx1wcQhRrd8ri9SCXeLbv?= =?us-ascii?Q?Li1muj40t6JccAxP39Cb+lLye6PcmCzD03RHupu3jadkulf6MZ4itDCJqALP?= =?us-ascii?Q?vnuz1TWJ9YEbps/bRrtB4aIiDhXkcEVi+GbeGWYZvtcOoKioINqp573dgVNQ?= =?us-ascii?Q?KApHC3/lGgtGJsGl/6iwseoLha2JNz0RulMKT1l+mkKqqnKstJPWq/+ZuxIc?= =?us-ascii?Q?mDj65dQ/xRBWzAWhFZqg7tsA0cs/EJQgVUpy+hZh9w2IIfpczw5WQ0fP7lUW?= =?us-ascii?Q?ebdNpiMY0xllcoku9HglFX8iJwOpSUfvGcCgrXZvGtjEZO1QzHo78t2wybW7?= =?us-ascii?Q?N3qTQIhwbQimFfNH3b092mPTL8QMEDPzeYmzgDinCxMN1cYwsZZvUVjZLdWZ?= =?us-ascii?Q?UO5rJXwfVaG9qk1I6zRd0wDP3rywTfsrDxW9aKaBfO1fHat4HZ1Y2NHpyz37?= =?us-ascii?Q?Q3pYPcxBNWWIeVT0I+L0uXnP6udjFld+1O+Mut6Cwszr7ItJxL8QDOe2WNqN?= =?us-ascii?Q?SnPArg8f+8Oc8mnwOsd3UfB0tm6NRpeSdH02mYuNmUTMhewujptOWW+OqkQ0?= =?us-ascii?Q?HhTUcF/tARJyy4BkESbFlLQAY2VUP87mYKIjTTWUsD9H1pGQrCRTP2e49XRW?= =?us-ascii?Q?LesrgE7VE9pA5/bRcSOmHDS5XHMqVO3LWGEnVbXcjcmf0QAh7z+2t5aAPpNK?= =?us-ascii?Q?Ox1t+OJUik+H9CV+jeRlXceK056rXm5ryu9BB9daiYYcs+aa5hWuj9G1hfqV?= =?us-ascii?Q?6niTMwsXv/mSDsFWFSXWasYjzJL0xpoXJRZI6q0pCwnsWqs/z8ybV567Wfv2?= =?us-ascii?Q?F0dwYbTTG19XIxFUaVl25UBGOUvMM6lMpeb8XHL+VnJU86wljuQt+RB4Q1LN?= =?us-ascii?Q?0kjCUI+faSsxFC8omm5bnVPsCndrPX+43f7u2kFyTfFCZluK7d3g/KqxnpWy?= =?us-ascii?Q?gXpVSeeQocbFqRF73yeVhsSYZgcv5AI6ObIo0JtnoWZwopVI+6X6v5Rf+/3B?= =?us-ascii?Q?9NVZWp+oU73838YLPXEut13ZOqnDr4GfSLffl1FGiKXqP6p2KG4MWPZIcKDD?= =?us-ascii?Q?mRNEuB9OHUBQWr4KjK5KK+4qxYW+H08xYZHBcFEprxqiQo0YKB9RKDBZLM6/?= =?us-ascii?Q?SN5d1gRdlzdX9JGBDkgrFqhWtfGhY78AyT2C5aYg6dxqyyk8XPfYOeGiShkM?= =?us-ascii?Q?p6amyUjC39B9Ym1M2Wb0OTuuOhi+?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS7PR11MB5966.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(366016)(1800799024);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?0UvamwhWvmMykxx+8cSQv3Hn9CDJZpW2NoWO8GbxA7I/57iPriDuLuLq3xgS?= =?us-ascii?Q?qQFWihMKZk0VaiEq8zJPlbJy/dlBCj8QXGiVGX84IXCccO55tukY1b/q51HP?= =?us-ascii?Q?dl8SbmAYObE6xmtOA3wMprvnJoyL1fEnOYwfAH6BmFSNUlm1mklgtNzWT92l?= =?us-ascii?Q?j9YJIDd6uzqCqzDLYJtB/pGSCVNLP3V6Q4PLNU6gLWPylWIyVClHwI2uT94s?= =?us-ascii?Q?BlXO3ehUCBS40rN7NwQprYJgY+cG1rcLtlFFas33lI0N3Y9vwddS7xRZk6Sx?= =?us-ascii?Q?/r6cziuyvzb4ZY7lt+5e/PxrD0Lv9+i1JJVqHVm62OVx3g7TIVwEszNVZPPl?= =?us-ascii?Q?Iiz6+kv1Tiy5Za4/vIQe7WfW1jo4flhgwlp5+dtAKdjL4w9cxVaLMj0GdgoH?= =?us-ascii?Q?NGHVKSSCgENf3zvvTnd2wd5wHoXbSIJciyzRjD+nbn/ng2su7c1oZnqekAVQ?= =?us-ascii?Q?M1Tn6WJU/4WwGnD0nr3NukjbcOZDaGdLGFS3qub6LctLBgOrPfwlf1pgT2Yi?= =?us-ascii?Q?iwbMl3tqEdEPxZHYscWNg3kc370KjFMCUsQNlR/hWlOLsrHeYnG1IKbYdOem?= =?us-ascii?Q?mlQwkvdAle+gtLt4zt1pgGEbOZmGIRiMXsQwv5ixAlArP6AK80bQj+0bhedb?= =?us-ascii?Q?4RZyDRNqkRlTNXu0HljGFbSVkG6DDkEW3KNNdLGIsi0PZ287Get/t4LyyHgn?= =?us-ascii?Q?Bt9tG1s4sfC/L85Z+6yxpUtB/NY6l6aJSxpDEsyKLoRn48tKE9Oo/SMnEFXC?= =?us-ascii?Q?pegJCvHzeuNZ9d+RE7KfwW2RXtJOTzPQwb2k8nh9bdCSvgMs4SKbVM/vAdIv?= =?us-ascii?Q?/JeMKqtuK4zdQyfuEdesNMGAU9ES6xSoZ1PkHDGIqwTLn8mxI0vvm1Hwp9PG?= =?us-ascii?Q?vHKvajVkkTAA/J2wFlDAsC1B7qMt6EwmxwGkb3cHsYyft6Cu6oR8j4Hd0ag6?= =?us-ascii?Q?A1adR6uk1c1SYP/AAO/OcswxOWNA7sFkGc1pnH7C1v3l+GRROvCYx5dIGIvk?= =?us-ascii?Q?++Ksd0u4ed4eJpSS+EO5y7HlpuB+PQ06EuCy7c4rjRdDzdLW6+v9midbi+j9?= =?us-ascii?Q?T6Y0ZR6gDuvsF9Zu1ZQCJ3+El8qHVogUMYMVjL+zg2Ta1OcyB7dM5AloGg47?= =?us-ascii?Q?NrUIbdWuOtcJ1kzgsFkK80gytYDMe7h6PAJ8SDiQvx1emvnLEjXdcMG+S3UM?= =?us-ascii?Q?QwkFDtZ5d0hnHf5s9I52BlwylJkY2f6UEtEb8QHUvipsfrxoBhOIW5Id0RAa?= =?us-ascii?Q?I9FeN9TgGARaqZIbvGmwOVw0tDW5KMv3ncilvzoninLl7h6AOLhWipoin2so?= =?us-ascii?Q?cHAJhYropSF6HVWG5Hs1UhtUVJtO/EsbKmD1a4g/qcOq1GzG2njTBUF6Dd7n?= =?us-ascii?Q?OcS0n6Uw+uquwNtm+6vAx3Pskiwg+9u9K5+NoabGGXHNYKSQnTafizGfV5im?= =?us-ascii?Q?yZ5uNJd9YS8tcAi7gdEdwytDO/yoeImQ882V8xHdCDzWwmGSx/qG/mWVPjRu?= =?us-ascii?Q?9lS2A+cqe0opBff9AFs4SuuNtGvRMadw9ZcWmK3NVO0BT4zoC0fAp/ZPRxhZ?= =?us-ascii?Q?XMnX5FQc4WbOSYuG/V10Zet5gW1ZuGoXLIo7pjB2?= X-MS-Exchange-CrossTenant-Network-Message-Id: 0ddee527-f19e-4fad-5700-08dd47e9ae2b X-MS-Exchange-CrossTenant-AuthSource: DS7PR11MB5966.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Feb 2025 02:38:33.2756 (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: XrrTcAq855TaVBdXlr7X7xQhhpJgzGoxJ+9Y2OXWE4F1UiWxhRjFNhktbjYGQ1mE2nkMxacKASqidA7XWlGx9g== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR11MB7337 X-OriginatorOrg: intel.com On Fri, Feb 07, 2025 at 07:07:06AM -0800, Sean Christopherson wrote: > On Fri, Feb 07, 2025, Yan Zhao wrote: > > Make sure pfn is not changed for a spurious fault by warning in the TDP > > MMU. For shadow path, only treat a prefetch fault as spurious when pfn is > > not changed, since the rmap removal and add are required when pfn is > > changed. > > I like sanity checks, but I don't like special casing "prefetch" faults like this. > KVM should _never_ change the PFN of a shadow-present SPTE. The TDP MMU already > BUG()s on this, and mmu_spte_update() WARNs on the transition. However, both TDP MMU and mmu_set_spte() return RET_PF_SPURIOUS directly before the BUG() in TDP MMU or mmu_spte_update() could be hit.