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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?aFhjf677NjFo7kVJuv2uXFwREePXF/4nld07+5pWqsLa8tw8LiuwdPP/RQJz?= =?us-ascii?Q?oPZgiHG/xXZwqZJTetGoML38MlBbRCyZYq0qcncBXE9LS+he4/rA1EvFnvr1?= =?us-ascii?Q?3s0qbpEBe/PSaDqYivYxD2gVBxRnxVmkj8hPrudJopwwGRnqCzPdoIa05jOC?= =?us-ascii?Q?W+HPk+wA1upMifjFsJT5WWfLIykJD7IdjFcViUS3Ei9GPqD6qDJqL0SiMIgR?= =?us-ascii?Q?7z5KfWYA/Ivg5+yBD1G2lSpQPmzVmB2KFjiwAs5uKOOof/b2Usuw1tEWCZtP?= =?us-ascii?Q?Wx1983iEzlXWqIw6TCN2D7PRW7MyFNHyUKYnEGklsqIeFCvQ1lmtFsvqtTnk?= =?us-ascii?Q?TZOVM7H6XwZCQrM8ySwpsHIdh4j7Gosay0TH6rVJH+TTXKxWEl2oLwZlgUOe?= =?us-ascii?Q?bT3qH7RGUYgsJV9B2ewxOfNCwiyO27Y9daEd7hfUeh+auTxogd4UwH3qnKGY?= =?us-ascii?Q?AzsiKyhpeG9OFqJ4TINLvQbz+eLFEp/SVPR/HTjbO3LWCKHJ8WYAyQOxkmx0?= =?us-ascii?Q?ShsPT8iatXU23mP8Ca84tsAhaJT0XcRHRl5nGQoNpBFSTPIHSs6PrYA9iSnA?= =?us-ascii?Q?vGCUo02vk4j6MdqmEzJmsz/KGEeZO2MG3sL/hQyigWl/ISTuX0IBa51p0gSy?= =?us-ascii?Q?r5XzjThtVUVS6YJGaQN3Yo1SYLfkb5hr3MmDfrXk0DdJMyYC58mLdhxddPWm?= =?us-ascii?Q?OGnuyfS/173v+e+lcukwGXAQwAmR72fXvCfmR5S3x/yzQYLX0RzbTXJgYoeg?= =?us-ascii?Q?BRCpNJihe+TAmv0TB3MxuyRVOeJi0IgqTpTZNoAQjOfyISgvQZB2eaKZXbct?= =?us-ascii?Q?uExwoivtxK1/reAKtfCH3bNkUB8XkJvqLkcVD7aObWhwGvbfEHOUO3XWk09+?= =?us-ascii?Q?xa2aRfzJGe8Ijwove5fpDm0NygYplOLk1tWFHbJsifABa7qPoDQ02BhHCotQ?= =?us-ascii?Q?pvoSn9D6/tEzOCdG9/Q3GqFuozIFXwQKldqI/o6INBxH71shBn+AX0xMQ6WI?= =?us-ascii?Q?QdSqXS1+4LUfn6jpT5TOTeY/tMtWq6HMao7r8HvKwz5GXNol063GhURdhBPy?= =?us-ascii?Q?X6nmiCuEFAFiBGDYOBMP1mYMx95Lm6wLDLy7x177M0ChAo6iTKsNagBeEsSt?= =?us-ascii?Q?Zz82LVeNR2eNmM0wFOfWNfhnRaYMjLBgp3wV7WnZWq6h3VBXdm/ui89I0eJV?= =?us-ascii?Q?bDy0Z4VWsxEEtb+U5zLS2tjNnYrAo3DaBmXbm0FE47UPzq56DjaIw7fjz0Zc?= =?us-ascii?Q?LxmornGpM7T1UA1UK1cErCooBcGv/J85osxvXoUkQYArimfGDmJLsuAPHMmP?= =?us-ascii?Q?wNrgSPy10HNhElE/nzV1aV75aB5Fj8xClisU3wyZi8cOh/YAOU4/3NxDGkfL?= =?us-ascii?Q?OLlvPS6YImmkY9IkZASt0mfPNLw6uX8OHnVZVamljwcMhw4EX1tZaeEwcOMJ?= =?us-ascii?Q?MZldQwznEle+Sw1UiQ3O6ELSNpXpSJA8bE8XdAXtv8MXQC196GB0K5tlVpXX?= =?us-ascii?Q?2EKS61I6ou2KdXOt5kOGn8PY7mK2gVC4vAE4PRJQfZI4W7j80NhrcD9JiCqA?= =?us-ascii?Q?aAFXv8Cb+s/OJC5R3RBCzR7fxrwrdcgbXf39XYuT?= X-MS-Exchange-CrossTenant-Network-Message-Id: c0e7717d-de13-4f72-bfab-08dd2ecac693 X-MS-Exchange-CrossTenant-AuthSource: CH3PR11MB8660.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jan 2025 03:24:20.7767 (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: nNtTbvTUclY2+gG2n+aJqg/FrrJzewIerA/Kubx81EOwB/MQcjEZs5Tx8URTVHymrtFZcIOacuwx3ddzuBPbSQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH0PR11MB5313 X-OriginatorOrg: intel.com >Note, kvm_use_posted_timer_interrupt() uses a heuristic of HLT/MWAIT interception >being disabled to detect that it's worth trying to post a timer interrupt, but off >the top of my head I'm pretty sure that's unnecessary and pointless. The Commit 1714a4eb6fb0 gives an explanation: if only some guests isolated and others not, they would not have any benefit from posted timer interrupts, and at the same time lose VMX preemption timer fast paths because kvm_can_post_timer_interrupt() returns true and therefore forces kvm_can_use_hv_timer() to false. >"vcpu->mode == IN_GUEST_MODE" is super cheap, and I can't think of any harm in >posting the time interrupt if the target vCPU happens to be in guest mode even >if the host wasn't configured just so. > >> Another scenario I was thinking of was hrtimer expiry during vcpu exit >> being handled in KVM/userspace, which will cause timer interrupt >> injection after the next exit [1] delaying timer interrupt to guest. > >No, the IRQ won't be delayed. Expiration from the hrtimer callback will set >KVM_REQ_UNBLOCK, which will prevent actually entering the guest (see the call >to kvm_request_pending() in kvm_vcpu_exit_request()). > >> This scenario is not specific to TDX VMs though. >> >> [1] https://git.kernel.org/pub/scm/virt/kvm/kvm.git/tree/arch/x86/kvm/x86.c?h=kvm-coco-queue#n11263