clocksource/drivers/hyperv: Enable TSC page clocksource on 32bit

There is no particular reason to not enable TSC page clocksource on 32-bit. mul_u64_u64_shr() is available and despite the increased computational complexity (compared to 64bit) TSC page is still a huge win compared to MSR-based clocksource. In-kernel reads: MSR based clocksource: 3361 cycles TSC page clocksource: 49 cycles Reads from userspace (utilizing vDSO in case of TSC page): MSR based clocksource: 5664 cycles TSC page clocksource: 131 cycles Enabling TSC page on 32bits allows to get rid of CONFIG_HYPERV_TSCPAGE as it is now not any different from CONFIG_HYPERV_TIMER. Signed-off-by: Vitaly Kuznetsov <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Michael Kelley <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
kawasaki · Aug 23, 2019 · 3e2d945 · 3e2d945
1 parent bd00cd5
commit 3e2d945
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Showing 4 changed files with 6 additions and 22 deletions.
diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -51,7 +51,7 @@ extern struct pvclock_vsyscall_time_info pvclock_page
 	__attribute__((visibility("hidden")));
 #endif
 
-#ifdef CONFIG_HYPERV_TSCPAGE
+#ifdef CONFIG_HYPERV_TIMER
 extern struct ms_hyperv_tsc_page hvclock_page
 	__attribute__((visibility("hidden")));
 #endif
@@ -192,7 +192,7 @@ static u64 vread_pvclock(void)
 }
 #endif
 
-#ifdef CONFIG_HYPERV_TSCPAGE
+#ifdef CONFIG_HYPERV_TIMER
 static u64 vread_hvclock(void)
 {
 	return hv_read_tsc_page(&hvclock_page);
@@ -215,7 +215,7 @@ static inline u64 __arch_get_hw_counter(s32 clock_mode)
 		return vread_pvclock();
 	}
 #endif
-#ifdef CONFIG_HYPERV_TSCPAGE
+#ifdef CONFIG_HYPERV_TIMER
 	if (clock_mode == VCLOCK_HVCLOCK) {
 		barrier();
 		return vread_hvclock();

diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
@@ -213,8 +213,6 @@ EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
 struct clocksource *hyperv_cs;
 EXPORT_SYMBOL_GPL(hyperv_cs);
 
-#ifdef CONFIG_HYPERV_TSCPAGE
-
 static struct ms_hyperv_tsc_page tsc_pg __aligned(PAGE_SIZE);
 
 struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
@@ -245,7 +243,6 @@ static struct clocksource hyperv_cs_tsc = {
 	.mask	= CLOCKSOURCE_MASK(64),
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
 };
-#endif
 
 static u64 notrace read_hv_clock_msr(struct clocksource *arg)
 {
@@ -272,7 +269,6 @@ static struct clocksource hyperv_cs_msr = {
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
-#ifdef CONFIG_HYPERV_TSCPAGE
 static bool __init hv_init_tsc_clocksource(void)
 {
 	u64		tsc_msr;
@@ -304,13 +300,6 @@ static bool __init hv_init_tsc_clocksource(void)
 
 	return true;
 }
-#else
-static bool __init hv_init_tsc_clocksource(void)
-{
-	return false;
-}
-#endif
-
 
 void __init hv_init_clocksource(void)
 {

diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
@@ -14,9 +14,6 @@ config HYPERV
 config HYPERV_TIMER
 	def_bool HYPERV
 
-config HYPERV_TSCPAGE
-       def_bool HYPERV && X86_64
-
 config HYPERV_UTILS
 	tristate "Microsoft Hyper-V Utilities driver"
 	depends on HYPERV && CONNECTOR && NLS

diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
@@ -28,12 +28,10 @@ extern void hv_stimer_cleanup(unsigned int cpu);
 extern void hv_stimer_global_cleanup(void);
 extern void hv_stimer0_isr(void);
 
-#if IS_ENABLED(CONFIG_HYPERV)
+#ifdef CONFIG_HYPERV_TIMER
 extern struct clocksource *hyperv_cs;
 extern void hv_init_clocksource(void);
-#endif /* CONFIG_HYPERV */
 
-#ifdef CONFIG_HYPERV_TSCPAGE
 extern struct ms_hyperv_tsc_page *hv_get_tsc_page(void);
 
 static inline notrace u64
@@ -91,7 +89,7 @@ hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
 	return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
 }
 
-#else /* CONFIG_HYPERV_TSC_PAGE */
+#else /* CONFIG_HYPERV_TIMER */
 static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
 {
 	return NULL;
@@ -102,6 +100,6 @@ static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
 {
 	return U64_MAX;
 }
-#endif /* CONFIG_HYPERV_TSCPAGE */
+#endif /* CONFIG_HYPERV_TIMER */
 
 #endif