From: Thomas Lefebvre <[email protected]> Sent: Tuesday, April 7, 2026 12:13 PM > > Hi everyone, thank you for your attention to this bug report. > > Michael, > > 1. No, lscpu in the L1 guest does not show the flags "tsc_reliable" > and "constant_tsc". > $ lscpu | grep tsc_reliable > $ lscpu | grep constant_tsc > $ cat /sys/devices/system/clocksource/clocksource0/current_clocksource > hyperv_clocksource_tsc_page > > 2. Windows 10 > Version 22H2 (OS Build 19045.6466) > > 3. Hyper-V: privilege flags low 0x2e7f, high 0x3b8030, ext 0x2, hints > 0x24e24, misc 0xbed7b2 > > 4. Yes, the laptop hibernates and then resumes. > When the problem occurred, the laptop had gone through multiple > hibernate and resume cycles. > I haven't seen it happen after a full reboot before a hibernate/resume cycle. > > Thomas >
How easy is it for you to reproduce the problem? Would it be feasible to get a definitive answer on whether the problem repros after a full reboot, but before a hibernate/resume cycle? There's a known bug Windows 10 Hyper-V where the hardware TSC scaling gets messed up after a hibernate/resume cycle, causing the TSC values read in the guest to drift from what the Hyper-V host thinks the guest's TSC value is. A summary of the problem is here: https://github.com/microsoft/WSL/issues/6982#issuecomment-2294892954 Of course, this doesn't sound like your symptom. And Hyper-V is not telling your guest that it supports hardware TSC scaling, because the HV_ACCESS_TSC_INVARIANT flag is *not* set and the clocksource is hyperv_clocksource_tsc_page. But my understanding is that the code changes to fix the Hyper-V problem weren't trivial, and I'm speculating that maybe you are seeing some other symptom of whatever the underlying Hyper-V issue was. Of course, this is just speculation. If the problem can occur before any hibernate/resume cycles are done, then my speculation is wrong. But if the problem only happens after a hibernate/resume cycle, then this known problem, or something related to it, becomes a pretty good candidate. Unfortunately, I'm pretty sure there's no fix for Windows 10 Hyper-V. You would need to upgrade to Windows 11 22H2 or later. Michael
