[PATCH 2/7] clocksource/drivers: Suspend/resume Hyper-V clocksource for hibernation
From: Dexuan Cui <decui@microsoft.com>
Date: 2019-07-09 05:29:39
Also in:
lkml
Subsystem:
clocksource, clockevent drivers, hyper-v/azure core and drivers, the rest · Maintainers:
Daniel Lezcano, Thomas Gleixner, "K. Y. Srinivasan", Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Linus Torvalds
This is needed for hibernation, e.g. when we resume the old kernel, we need to disable the "current" kernel's TSC page and then resume the old kernel's. Signed-off-by: Dexuan Cui <decui@microsoft.com> --- drivers/clocksource/hyperv_timer.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index ba2c79e6..41c31a7 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c@@ -237,12 +237,37 @@ static u64 read_hv_clock_tsc(struct clocksource *arg) return read_hv_sched_clock_tsc(); } +static void suspend_hv_clock_tsc(struct clocksource *arg) +{ + u64 tsc_msr; + + /* Disable the TSC page */ + hv_get_reference_tsc(tsc_msr); + tsc_msr &= ~BIT_ULL(0); + hv_set_reference_tsc(tsc_msr); +} + + +static void resume_hv_clock_tsc(struct clocksource *arg) +{ + phys_addr_t phys_addr = page_to_phys(vmalloc_to_page(tsc_pg)); + u64 tsc_msr; + + /* Re-enable the TSC page */ + hv_get_reference_tsc(tsc_msr); + tsc_msr &= GENMASK_ULL(11, 0); + tsc_msr |= BIT_ULL(0) | (u64)phys_addr; + hv_set_reference_tsc(tsc_msr); +} + static struct clocksource hyperv_cs_tsc = { .name = "hyperv_clocksource_tsc_page", .rating = 400, .read = read_hv_clock_tsc, .mask = CLOCKSOURCE_MASK(64), .flags = CLOCK_SOURCE_IS_CONTINUOUS, + .suspend= suspend_hv_clock_tsc, + .resume = resume_hv_clock_tsc, }; #endif
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1.8.3.1