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 <vkuznets@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lkml.kernel.org/r/20190822083630.17059-1-vkuznets@redhat.com

diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
index ae91429129a6411b8cd324f911ec1b5b57085365..bcbf901befbe07dcc3867ab05a612b9410103f26 100644 (file)
--- 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
index c322ab4d3689ad365822d02f1dc6e5623fb236c8..2317d4e3daaffc2de01105f2b43cccc159ca5c20 100644 (file)
--- 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
index 9a59957922d41e82e763260a41e98c158e77cbea..79e5356a737a2ad6b9fb19a498613eba20aa9761 100644 (file)
--- 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
index a821deb8ecb28c6c09bb2b4e80ea785498b29e3e..422f5e5237be4f5bca2374bcdbf794a33cc6dd4a 100644 (file)
--- 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