diff options
author | Tianyu Lan <Tianyu.Lan@microsoft.com> | 2019-08-14 20:32:16 +0800 |
---|---|---|
committer | Thomas Gleixner <tglx@linutronix.de> | 2019-08-23 16:59:54 +0200 |
commit | bd00cd52d5be655a2f217e2ed74b91a71cb2b14f (patch) | |
tree | 90b8fe8d71a849f6066d1c2ba7500dba0fca9819 /drivers/clocksource/hyperv_timer.c | |
parent | adb87ff4f96c9700718e09c97a804124d5cd61ff (diff) | |
download | linux-bd00cd52d5be655a2f217e2ed74b91a71cb2b14f.tar.bz2 |
clocksource/drivers/hyperv: Add Hyper-V specific sched clock function
Hyper-V guests use the default native_sched_clock() in
pv_ops.time.sched_clock on x86. But native_sched_clock() directly uses the
raw TSC value, which can be discontinuous in a Hyper-V VM.
Add the generic hv_setup_sched_clock() to set the sched clock function
appropriately. On x86, this sets pv_ops.time.sched_clock to read the
Hyper-V reference TSC value that is scaled and adjusted to be continuous.
Also move the Hyper-V reference TSC initialization much earlier in the boot
process so no discontinuity is observed when pv_ops.time.sched_clock
calculates its offset.
[ tglx: Folded build fix ]
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lkml.kernel.org/r/20190814123216.32245-3-Tianyu.Lan@microsoft.com
Diffstat (limited to 'drivers/clocksource/hyperv_timer.c')
-rw-r--r-- | drivers/clocksource/hyperv_timer.c | 22 |
1 files changed, 12 insertions, 10 deletions
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c index 432aa331df04..c322ab4d3689 100644 --- a/drivers/clocksource/hyperv_timer.c +++ b/drivers/clocksource/hyperv_timer.c @@ -22,6 +22,7 @@ #include <asm/mshyperv.h> static struct clock_event_device __percpu *hv_clock_event; +static u64 hv_sched_clock_offset __ro_after_init; /* * If false, we're using the old mechanism for stimer0 interrupts @@ -222,7 +223,7 @@ struct ms_hyperv_tsc_page *hv_get_tsc_page(void) } EXPORT_SYMBOL_GPL(hv_get_tsc_page); -static u64 notrace read_hv_sched_clock_tsc(void) +static u64 notrace read_hv_clock_tsc(struct clocksource *arg) { u64 current_tick = hv_read_tsc_page(&tsc_pg); @@ -232,9 +233,9 @@ static u64 notrace read_hv_sched_clock_tsc(void) return current_tick; } -static u64 read_hv_clock_tsc(struct clocksource *arg) +static u64 read_hv_sched_clock_tsc(void) { - return read_hv_sched_clock_tsc(); + return read_hv_clock_tsc(NULL) - hv_sched_clock_offset; } static struct clocksource hyperv_cs_tsc = { @@ -246,7 +247,7 @@ static struct clocksource hyperv_cs_tsc = { }; #endif -static u64 notrace read_hv_sched_clock_msr(void) +static u64 notrace read_hv_clock_msr(struct clocksource *arg) { u64 current_tick; /* @@ -258,9 +259,9 @@ static u64 notrace read_hv_sched_clock_msr(void) return current_tick; } -static u64 read_hv_clock_msr(struct clocksource *arg) +static u64 read_hv_sched_clock_msr(void) { - return read_hv_sched_clock_msr(); + return read_hv_clock_msr(NULL) - hv_sched_clock_offset; } static struct clocksource hyperv_cs_msr = { @@ -298,8 +299,9 @@ static bool __init hv_init_tsc_clocksource(void) hv_set_clocksource_vdso(hyperv_cs_tsc); clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100); - /* sched_clock_register is needed on ARM64 but is a no-op on x86 */ - sched_clock_register(read_hv_sched_clock_tsc, 64, HV_CLOCK_HZ); + hv_sched_clock_offset = hyperv_cs->read(hyperv_cs); + hv_setup_sched_clock(read_hv_sched_clock_tsc); + return true; } #else @@ -329,7 +331,7 @@ void __init hv_init_clocksource(void) hyperv_cs = &hyperv_cs_msr; clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100); - /* sched_clock_register is needed on ARM64 but is a no-op on x86 */ - sched_clock_register(read_hv_sched_clock_msr, 64, HV_CLOCK_HZ); + hv_sched_clock_offset = hyperv_cs->read(hyperv_cs); + hv_setup_sched_clock(read_hv_sched_clock_msr); } EXPORT_SYMBOL_GPL(hv_init_clocksource); |