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

[Michael Kelley]

From: Dexuan Cui  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 
> ---
>  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 

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

[Dexuan Cui]

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 
---
 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