2019-07-09 05:31:05

by Dexuan Cui

Subject: [PATCH 2/7] clocksource/drivers: Suspend/resume Hyper-V clocksource for hibernation

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 <[email protected]>
---
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

--
1.8.3.1

2019-07-31 00:17:48

by Michael Kelley (LINUX)

Subject: RE: [PATCH 2/7] clocksource/drivers: Suspend/resume Hyper-V clocksource for hibernation

From: Dexuan Cui <[email protected]> Sent: Monday, July 8, 2019 10:29 PM
>
> 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 <[email protected]>
> ---
> 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
>
> --
> 1.8.3.1

Reviewed-by: Michael Kelley <[email protected]>