clocksource/drivers/hyper-v: Handle vDSO differences inline

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@microsoft.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1614721102-2241-8-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
(cherry picked from commit e4ab465)
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

Author: kelleymh

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()
 
 /*

drivers/clocksource/hyperv_timer.c

@@ -370,11 +370,13 @@ static void resume_hv_clock_tsc(struct clocksource *arg)
 	hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr);
 }
 
+#ifdef VDSO_CLOCKMODE_HVCLOCK
 static int hv_cs_enable(struct clocksource *cs)
 {
-	hv_enable_vdso_clocksource();
+	vclocks_set_used(VDSO_CLOCKMODE_HVCLOCK);
 	return 0;
 }
+#endif
 
 static struct clocksource hyperv_cs_tsc = {
 	.name	= "hyperv_clocksource_tsc_page",
@@ -384,7 +386,12 @@ static struct clocksource hyperv_cs_tsc = {
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
 	.suspend= suspend_hv_clock_tsc,
 	.resume	= resume_hv_clock_tsc,
+#ifdef VDSO_CLOCKMODE_HVCLOCK
 	.enable = hv_cs_enable,
+	.vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK,
+#else
+	.vdso_clock_mode = VDSO_CLOCKMODE_NONE,
+#endif
 };
 
 static u64 notrace read_hv_clock_msr(void)
@@ -439,7 +446,6 @@ 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();