diff options
Diffstat (limited to 'drivers/clocksource/hyperv_timer.c')
| -rw-r--r-- | drivers/clocksource/hyperv_timer.c | 23 |
1 files changed, 13 insertions, 10 deletions
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c index 10eb5c645141..7a9030ca68c4 100644 --- a/drivers/clocksource/hyperv_timer.c +++ b/drivers/clocksource/hyperv_timer.c @@ -302,14 +302,6 @@ 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); @@ -380,7 +372,7 @@ static int hv_cs_enable(struct clocksource *cs) static struct clocksource hyperv_cs_tsc = { .name = "hyperv_clocksource_tsc_page", - .rating = 250, + .rating = 500, .read = read_hv_clock_tsc_cs, .mask = CLOCKSOURCE_MASK(64), .flags = CLOCK_SOURCE_IS_CONTINUOUS, @@ -417,7 +409,7 @@ static u64 notrace read_hv_sched_clock_msr(void) static struct clocksource hyperv_cs_msr = { .name = "hyperv_clocksource_msr", - .rating = 250, + .rating = 500, .read = read_hv_clock_msr_cs, .mask = CLOCKSOURCE_MASK(64), .flags = CLOCK_SOURCE_IS_CONTINUOUS, @@ -458,6 +450,17 @@ static bool __init hv_init_tsc_clocksource(void) if (hv_root_partition) return false; + /* + * 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. + */ + if (ms_hyperv.features & HV_ACCESS_TSC_INVARIANT) + hyperv_cs_tsc.rating = 250; + hv_read_reference_counter = read_hv_clock_tsc; phys_addr = virt_to_phys(hv_get_tsc_page()); |