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Subject[RFC 6/6] arm64: hyperv: Enable vDSO
Date
Similar to x86, add a new vclock_mode VCLOCK_HVCLOCK, and reuse the
hv_read_tsc_page() for userspace to read tsc page clocksource.

Signed-off-by: Boqun Feng (Microsoft) <boqun.feng@gmail.com>
---
arch/arm64/include/asm/clocksource.h | 3 ++-
arch/arm64/include/asm/mshyperv.h | 2 +-
arch/arm64/include/asm/vdso/gettimeofday.h | 19 +++++++++++++++++++
3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/clocksource.h b/arch/arm64/include/asm/clocksource.h
index fbe80057468c..c6acd45fe748 100644
--- a/arch/arm64/include/asm/clocksource.h
+++ b/arch/arm64/include/asm/clocksource.h
@@ -4,7 +4,8 @@

#define VCLOCK_NONE 0 /* No vDSO clock available. */
#define VCLOCK_CNTVCT 1 /* vDSO should use cntvcnt */
-#define VCLOCK_MAX 1
+#define VCLOCK_HVCLOCK 2 /* vDSO should use vread_hvclock() */
+#define VCLOCK_MAX 2

struct arch_clocksource_data {
int vclock_mode;
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index 0afb00e3501d..7c85dd816dca 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -90,7 +90,7 @@ extern void hv_get_vpreg_128(u32 reg, struct hv_get_vp_register_output *result);
#define hv_set_reference_tsc(val) \
hv_set_vpreg(HV_REGISTER_REFERENCE_TSC, val)
#define hv_set_clocksource_vdso(val) \
- ((val).archdata.vclock_mode = VCLOCK_NONE)
+ ((val).archdata.vclock_mode = VCLOCK_HVCLOCK)

#if IS_ENABLED(CONFIG_HYPERV)
#define hv_enable_stimer0_percpu_irq(irq) enable_percpu_irq(irq, 0)
diff --git a/arch/arm64/include/asm/vdso/gettimeofday.h b/arch/arm64/include/asm/vdso/gettimeofday.h
index e6e3fe0488c7..7e689b903f4d 100644
--- a/arch/arm64/include/asm/vdso/gettimeofday.h
+++ b/arch/arm64/include/asm/vdso/gettimeofday.h
@@ -67,6 +67,20 @@ int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
return ret;
}

+#ifdef CONFIG_HYPERV_TIMER
+/* This will override the default hv_get_raw_timer() */
+#define hv_get_raw_timer() __arch_counter_get_cntvct()
+#include <clocksource/hyperv_timer.h>
+
+extern struct ms_hyperv_tsc_page
+_hvclock_page __attribute__((visibility("hidden")));
+
+static u64 vread_hvclock(void)
+{
+ return hv_read_tsc_page(&_hvclock_page);
+}
+#endif
+
static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
{
u64 res;
@@ -78,6 +92,11 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
if (clock_mode == VCLOCK_NONE)
return __VDSO_USE_SYSCALL;

+#ifdef CONFIG_HYPERV_TIMER
+ if (likely(clock_mode == VCLOCK_HVCLOCK))
+ return vread_hvclock();
+#endif
+
/*
* This isb() is required to prevent that the counter value
* is speculated.
--
2.24.0
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