diff options
| -rw-r--r-- | arch/x86/kernel/cpu/mshyperv.c | 11 | ||||
| -rw-r--r-- | drivers/clocksource/hyperv_timer.c | 10 |
2 files changed, 19 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index c78f860419d6..25773af116bc 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -565,6 +565,11 @@ static void __init ms_hyperv_init_platform(void) machine_ops.crash_shutdown = hv_machine_crash_shutdown; #endif #endif + /* + * HV_ACCESS_TSC_INVARIANT is always zero for the root partition. Root + * partition doesn't need to write to synthetic MSR to enable invariant + * TSC feature. It sees what the hardware provides. + */ if (ms_hyperv.features & HV_ACCESS_TSC_INVARIANT) { /* * Writing to synthetic MSR 0x40000118 updates/changes the @@ -636,8 +641,12 @@ static void __init ms_hyperv_init_platform(void) * TSC should be marked as unstable only after Hyper-V * clocksource has been initialized. This ensures that the * stability of the sched_clock is not altered. + * + * HV_ACCESS_TSC_INVARIANT is always zero for the root partition. No + * need to check for it. */ - if (!(ms_hyperv.features & HV_ACCESS_TSC_INVARIANT)) + if (!hv_root_partition() && + !(ms_hyperv.features & HV_ACCESS_TSC_INVARIANT)) mark_tsc_unstable("running on Hyper-V"); hardlockup_detector_disable(); diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c index 2edc13ca184e..10356d4ec55c 100644 --- a/drivers/clocksource/hyperv_timer.c +++ b/drivers/clocksource/hyperv_timer.c @@ -549,14 +549,22 @@ static void __init hv_init_tsc_clocksource(void) union hv_reference_tsc_msr tsc_msr; /* + * When running as a guest partition: + * * If Hyper-V offers TSC_INVARIANT, then the virtualized TSC correctly * handles frequency and offset changes due to live migration, * pause/resume, and other VM management operations. So lower the * Hyper-V Reference TSC rating, causing the generic TSC to be used. * TSC_INVARIANT is not offered on ARM64, so the Hyper-V Reference * TSC will be preferred over the virtualized ARM64 arch counter. + * + * When running as the root partition: + * + * There is no HV_ACCESS_TSC_INVARIANT feature. Always lower the rating + * of the Hyper-V Reference TSC. */ - if (ms_hyperv.features & HV_ACCESS_TSC_INVARIANT) { + if ((ms_hyperv.features & HV_ACCESS_TSC_INVARIANT) || + hv_root_partition()) { hyperv_cs_tsc.rating = 250; hyperv_cs_msr.rating = 245; } |