diff options
Diffstat (limited to 'drivers/clocksource/hyperv_timer.c')
| -rw-r--r-- | drivers/clocksource/hyperv_timer.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c index 42748adccc98..9d808d595ca8 100644 --- a/drivers/clocksource/hyperv_timer.c +++ b/drivers/clocksource/hyperv_timer.c @@ -302,6 +302,14 @@ EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup); * the other that uses the TSC reference page feature as defined in the * TLFS. The MSR version is for compatibility with old versions of * Hyper-V and 32-bit x86. The TSC reference page version is preferred. + * + * The Hyper-V clocksource ratings of 250 are chosen to be below the + * TSC clocksource rating of 300. In configurations where Hyper-V offers + * an InvariantTSC, the TSC is not marked "unstable", so the TSC clocksource + * is available and preferred. With the higher rating, it will be the + * default. On older hardware and Hyper-V versions, the TSC is marked + * "unstable", so no TSC clocksource is created and the selected Hyper-V + * clocksource will be the default. */ u64 (*hv_read_reference_counter)(void); @@ -363,7 +371,7 @@ static void resume_hv_clock_tsc(struct clocksource *arg) static struct clocksource hyperv_cs_tsc = { .name = "hyperv_clocksource_tsc_page", - .rating = 400, + .rating = 250, .read = read_hv_clock_tsc_cs, .mask = CLOCKSOURCE_MASK(64), .flags = CLOCK_SOURCE_IS_CONTINUOUS, @@ -395,7 +403,7 @@ static u64 read_hv_sched_clock_msr(void) static struct clocksource hyperv_cs_msr = { .name = "hyperv_clocksource_msr", - .rating = 400, + .rating = 250, .read = read_hv_clock_msr_cs, .mask = CLOCKSOURCE_MASK(64), .flags = CLOCK_SOURCE_IS_CONTINUOUS, |