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Subject[PATCH v3 08/10] clocksource/drivers/hyper-v: Handle sched_clock differences inline
Date
While the Hyper-V Reference TSC code is architecture neutral, the
pv_ops.time.sched_clock() function is implemented for x86/x64, but not
for ARM64. Current code calls a utility function under arch/x86 (and
coming, under arch/arm64) to handle the difference.

Change this approach to handle the difference inline based on whether
GENERIC_SCHED_CLOCK 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>
---
arch/x86/include/asm/mshyperv.h | 11 -----------
drivers/clocksource/hyperv_timer.c | 24 ++++++++++++++++++++++++
2 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 4f566db..5433312 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -29,17 +29,6 @@ static inline u64 hv_get_register(unsigned int reg)

#define hv_get_raw_timer() rdtsc_ordered()

-/*
- * Reference to pv_ops must be inline so objtool
- * detection of noinstr violations can work correctly.
- */
-static __always_inline void hv_setup_sched_clock(void *sched_clock)
-{
-#ifdef CONFIG_PARAVIRT
- pv_ops.time.sched_clock = sched_clock;
-#endif
-}
-
void hyperv_vector_handler(struct pt_regs *regs);

static inline void hv_enable_stimer0_percpu_irq(int irq) {}
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 06984fa..10eb5c6 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -423,6 +423,30 @@ static u64 notrace read_hv_sched_clock_msr(void)
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};

+/*
+ * Reference to pv_ops must be inline so objtool
+ * detection of noinstr violations can work correctly.
+ */
+#ifdef CONFIG_GENERIC_SCHED_CLOCK
+static __always_inline void hv_setup_sched_clock(void *sched_clock)
+{
+ /*
+ * We're on an architecture with generic sched clock (not x86/x64).
+ * The Hyper-V sched clock read function returns nanoseconds, not
+ * the normal 100ns units of the Hyper-V synthetic clock.
+ */
+ sched_clock_register(sched_clock, 64, NSEC_PER_SEC);
+}
+#elif defined CONFIG_PARAVIRT
+static __always_inline void hv_setup_sched_clock(void *sched_clock)
+{
+ /* We're on x86/x64 *and* using PV ops */
+ pv_ops.time.sched_clock = sched_clock;
+}
+#else /* !CONFIG_GENERIC_SCHED_CLOCK && !CONFIG_PARAVIRT */
+static __always_inline void hv_setup_sched_clock(void *sched_clock) {}
+#endif /* CONFIG_GENERIC_SCHED_CLOCK */
+
static bool __init hv_init_tsc_clocksource(void)
{
u64 tsc_msr;
--
1.8.3.1
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