clocksource/drivers/hyper-v: 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]>
Reviewed-by: Michael Kelley <[email protected]>
Signed-off-by: Daniel Lezcano <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 287d8d58c21ac15a4a72860ff8a433d3ce8caa34..1aec08e82b7a8cff673dc395f7a618a62e9369be 100644 (file)
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -330,12 +330,37 @@ static u64 read_hv_sched_clock_tsc(void)
        return read_hv_clock_tsc(NULL) - hv_sched_clock_offset;
 }
 
+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 = virt_to_phys(&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,
 };
 
 static u64 notrace read_hv_clock_msr(struct clocksource *arg)