[PATCH v2 07/10] clocksource/drivers/hyper-v: Handle vDSO differences inline

From: Michael Kelley
Date: Sun Feb 28 2021 - 20:19:58 EST


While the driver for the Hyper-V Reference TSC and STIMERs is architecture
neutral, vDSO is implemented for x86/x64, but not for ARM64. Current code
calls into utility functions under arch/x86 (and coming, under arch/arm64)
to handle the difference.

Change this approach to handle the difference inline based on whether
VDSO_CLOCK_MODE_HVCLOCK is present. The new approach removes code under
arch/* since the difference is tied more to the specifics of the Linux
implementation than to the architecture.

No functional change.

Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Reviewed-by: Boqun Feng <boqun.feng@xxxxxxxxx>
---
arch/x86/include/asm/mshyperv.h | 4 ----
drivers/clocksource/hyperv_timer.c | 10 ++++++++--
2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index c10dd1c..4f566db 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -27,10 +27,6 @@ static inline u64 hv_get_register(unsigned int reg)
return value;
}

-#define hv_set_clocksource_vdso(val) \
- ((val).vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK)
-#define hv_enable_vdso_clocksource() \
- vclocks_set_used(VDSO_CLOCKMODE_HVCLOCK);
#define hv_get_raw_timer() rdtsc_ordered()

/*
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index c73c127..5e5e08aa 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -372,7 +372,9 @@ static void resume_hv_clock_tsc(struct clocksource *arg)

static int hv_cs_enable(struct clocksource *cs)
{
- hv_enable_vdso_clocksource();
+#ifdef VDSO_CLOCKMODE_HVCLOCK
+ vclocks_set_used(VDSO_CLOCKMODE_HVCLOCK);
+#endif
return 0;
}

@@ -385,6 +387,11 @@ static int hv_cs_enable(struct clocksource *cs)
.suspend= suspend_hv_clock_tsc,
.resume = resume_hv_clock_tsc,
.enable = hv_cs_enable,
+#ifdef VDSO_CLOCKMODE_HVCLOCK
+ .vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK,
+#else
+ .vdso_clock_mode = VDSO_CLOCKMODE_NONE,
+#endif
};

static u64 notrace read_hv_clock_msr(void)
@@ -442,7 +449,6 @@ static bool __init hv_init_tsc_clocksource(void)
tsc_msr = tsc_msr | 0x1 | (u64)phys_addr;
hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr);

- hv_set_clocksource_vdso(hyperv_cs_tsc);
clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);

hv_sched_clock_offset = hv_read_reference_counter();
--
1.8.3.1