[PATCH v5 0/2] clocksource/drivers: Create new Hyper-V clocksource driver

[PATCH v5 0/2] clocksource/drivers: Create new Hyper-V clocksource driver

[Michael Kelley]

This patch series moves Hyper-V clock/timer code to a separate Hyper-V
clocksource driver. Previously, Hyper-V clock/timer code and data
structures were mixed in with other Hyper-V code in the ISA independent
drivers/hv code as well as in ISA dependent code. The new Hyper-V
clocksource driver is ISA agnostic, with a just few dependencies on
ISA specific functions. The patch series does not change any behavior
or functionality -- it only reorganizes the existing code and fixes up
the linkages. A few places outside of Hyper-V code are fixed up to use
the new #include file structure.

This restructuring is in response to Marc Zyngier's review comments
on supporting Hyper-V running on ARM64, and is a good idea in general.
It increases the amount of code shared between the x86 and ARM64
architectures, and reduces the size of the new code for supporting
Hyper-V on ARM64. A new version of the Hyper-V on ARM64 patches will
follow once this clocksource restructuring is accepted.

The code is diff'ed against the upstream tip tree:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/vdso

Changes in v5:
* Revised commit summaries [Thomas Gleixner]
* Removed call to clockevents_unbind_device() [Thomas Gleixner]
* Restructured hv_init_clocksource() [Thomas Gleixner]
* Various other small code cleanups [Thomas Gleixner]

Changes in v4:
* Revised commit messages
* Rebased to upstream tip tree

Changes in v3:
* Removed boolean argument to hv_init_clocksource(). Always call
sched_clock_register, which is needed on ARM64 but a no-op on x86.
* Removed separate cpuhp setup in hv_stimer_alloc() and instead
directly call hv_stimer_init() and hv_stimer_cleanup() from
corresponding VMbus functions.  This more closely matches original
code and avoids clocksource stop/restart problems on ARM64 when
VMbus code denies CPU offlining request.

Changes in v2:
* Revised commit short descriptions so the distinction between
the first and second patches is clearer [GregKH]
* Renamed new clocksource driver files and functions to use
existing "timer" and "stimer" names instead of introducing
"syntimer". [Vitaly Kuznetsov]
* Introduced CONFIG_HYPER_TIMER to fix build problem when
CONFIG_HYPERV=m [Vitaly Kuznetsov]
* Added "Suggested-by: Marc Zyngier"

Michael Kelley (2):
  clocksource/drivers: Make Hyper-V clocksource ISA agnostic
  clocksource/drivers: Continue making Hyper-V clocksource ISA agnostic

 MAINTAINERS                              |   2 +
 arch/x86/entry/vdso/vma.c                |   2 +-
 arch/x86/hyperv/hv_init.c                |  91 +--------
 arch/x86/include/asm/hyperv-tlfs.h       |   6 +
 arch/x86/include/asm/mshyperv.h          |  81 +-------
 arch/x86/include/asm/vdso/gettimeofday.h |   2 +-
 arch/x86/kernel/cpu/mshyperv.c           |   4 +-
 arch/x86/kvm/x86.c                       |   1 +
 drivers/clocksource/Makefile             |   1 +
 drivers/clocksource/hyperv_timer.c       | 339 +++++++++++++++++++++++++++++++
 drivers/hv/Kconfig                       |   3 +
 drivers/hv/hv.c                          | 156 +-------------
 drivers/hv/hv_util.c                     |   1 +
 drivers/hv/hyperv_vmbus.h                |   3 -
 drivers/hv/vmbus_drv.c                   |  42 ++--
 include/clocksource/hyperv_timer.h       | 105 ++++++++++
 16 files changed, 503 insertions(+), 336 deletions(-)
 create mode 100644 drivers/clocksource/hyperv_timer.c
 create mode 100644 include/clocksource/hyperv_timer.h

-- 
1.8.3.1

[PATCH v5 0/2] clocksource/drivers: Create new Hyper-V clocksource driver

[Michael Kelley]

This patch series moves Hyper-V clock/timer code to a separate Hyper-V
clocksource driver. Previously, Hyper-V clock/timer code and data
structures were mixed in with other Hyper-V code in the ISA independent
drivers/hv code as well as in ISA dependent code. The new Hyper-V
clocksource driver is ISA agnostic, with a just few dependencies on
ISA specific functions. The patch series does not change any behavior
or functionality -- it only reorganizes the existing code and fixes up
the linkages. A few places outside of Hyper-V code are fixed up to use
the new #include file structure.

This restructuring is in response to Marc Zyngier's review comments
on supporting Hyper-V running on ARM64, and is a good idea in general.
It increases the amount of code shared between the x86 and ARM64
architectures, and reduces the size of the new code for supporting
Hyper-V on ARM64. A new version of the Hyper-V on ARM64 patches will
follow once this clocksource restructuring is accepted.

The code is diff'ed against the upstream tip tree:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/vdso

Changes in v5:
* Revised commit summaries [Thomas Gleixner]
* Removed call to clockevents_unbind_device() [Thomas Gleixner]
* Restructured hv_init_clocksource() [Thomas Gleixner]
* Various other small code cleanups [Thomas Gleixner]

Changes in v4:
* Revised commit messages
* Rebased to upstream tip tree

Changes in v3:
* Removed boolean argument to hv_init_clocksource(). Always call
sched_clock_register, which is needed on ARM64 but a no-op on x86.
* Removed separate cpuhp setup in hv_stimer_alloc() and instead
directly call hv_stimer_init() and hv_stimer_cleanup() from
corresponding VMbus functions.  This more closely matches original
code and avoids clocksource stop/restart problems on ARM64 when
VMbus code denies CPU offlining request.

Changes in v2:
* Revised commit short descriptions so the distinction between
the first and second patches is clearer [GregKH]
* Renamed new clocksource driver files and functions to use
existing "timer" and "stimer" names instead of introducing
"syntimer". [Vitaly Kuznetsov]
* Introduced CONFIG_HYPER_TIMER to fix build problem when
CONFIG_HYPERV=m [Vitaly Kuznetsov]
* Added "Suggested-by: Marc Zyngier"

Michael Kelley (2):
  clocksource/drivers: Make Hyper-V clocksource ISA agnostic
  clocksource/drivers: Continue making Hyper-V clocksource ISA agnostic

 MAINTAINERS                              |   2 +
 arch/x86/entry/vdso/vma.c                |   2 +-
 arch/x86/hyperv/hv_init.c                |  91 +--------
 arch/x86/include/asm/hyperv-tlfs.h       |   6 +
 arch/x86/include/asm/mshyperv.h          |  81 +-------
 arch/x86/include/asm/vdso/gettimeofday.h |   2 +-
 arch/x86/kernel/cpu/mshyperv.c           |   4 +-
 arch/x86/kvm/x86.c                       |   1 +
 drivers/clocksource/Makefile             |   1 +
 drivers/clocksource/hyperv_timer.c       | 339 +++++++++++++++++++++++++++++++
 drivers/hv/Kconfig                       |   3 +
 drivers/hv/hv.c                          | 156 +-------------
 drivers/hv/hv_util.c                     |   1 +
 drivers/hv/hyperv_vmbus.h                |   3 -
 drivers/hv/vmbus_drv.c                   |  42 ++--
 include/clocksource/hyperv_timer.h       | 105 ++++++++++
 16 files changed, 503 insertions(+), 336 deletions(-)
 create mode 100644 drivers/clocksource/hyperv_timer.c
 create mode 100644 include/clocksource/hyperv_timer.h

-- 
1.8.3.1

[PATCH v5 1/2] clocksource/drivers: Make Hyper-V clocksource ISA agnostic

[Michael Kelley]

Hyper-V clock/timer code and data structures are currently mixed
in with other code in the ISA independent drivers/hv directory as
well as the ISA dependent Hyper-V code under arch/x86.  Consolidate
this code and data structures into a Hyper-V clocksource driver to
better follow the Linux model. In doing so, separate out the ISA
dependent portions so the new clocksource driver works for x86 and
for the in-process Hyper-V on ARM64 code.

To start, move the existing clockevents code to create the
new clocksource driver. Update the VMbus driver to call
initialization and cleanup routines since the Hyper-V
synthetic timers are not independently enumerated in ACPI.

No behavior is changed and no new functionality is added.

Suggested-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
---
 MAINTAINERS                        |   2 +
 arch/x86/include/asm/hyperv-tlfs.h |   6 ++
 arch/x86/kernel/cpu/mshyperv.c     |   4 +-
 drivers/clocksource/Makefile       |   1 +
 drivers/clocksource/hyperv_timer.c | 200 +++++++++++++++++++++++++++++++++++++
 drivers/hv/Kconfig                 |   3 +
 drivers/hv/hv.c                    | 156 +----------------------------
 drivers/hv/hyperv_vmbus.h          |   3 -
 drivers/hv/vmbus_drv.c             |  42 ++++----
 include/clocksource/hyperv_timer.h |  27 +++++
 10 files changed, 268 insertions(+), 176 deletions(-)
 create mode 100644 drivers/clocksource/hyperv_timer.c
 create mode 100644 include/clocksource/hyperv_timer.h

diff --git a/MAINTAINERS b/MAINTAINERS
index a281297..bfde42a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7313,6 +7313,7 @@ F:	arch/x86/include/asm/trace/hyperv.h
 F:	arch/x86/include/asm/hyperv-tlfs.h
 F:	arch/x86/kernel/cpu/mshyperv.c
 F:	arch/x86/hyperv
+F:	drivers/clocksource/hyperv_timer.c
 F:	drivers/hid/hid-hyperv.c
 F:	drivers/hv/
 F:	drivers/input/serio/hyperv-keyboard.c
@@ -7323,6 +7324,7 @@ F:	drivers/uio/uio_hv_generic.c
 F:	drivers/video/fbdev/hyperv_fb.c
 F:	drivers/iommu/hyperv_iommu.c
 F:	net/vmw_vsock/hyperv_transport.c
+F:	include/clocksource/hyperv_timer.h
 F:	include/linux/hyperv.h
 F:	include/uapi/linux/hyperv.h
 F:	tools/hv/
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index cdf44aa..af78cd7 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -401,6 +401,12 @@ enum HV_GENERIC_SET_FORMAT {
 #define HV_STATUS_INVALID_CONNECTION_ID		18
 #define HV_STATUS_INSUFFICIENT_BUFFERS		19
 
+/*
+ * The Hyper-V TimeRefCount register and the TSC
+ * page provide a guest VM clock with 100ns tick rate
+ */
+#define HV_CLOCK_HZ (NSEC_PER_SEC/100)
+
 typedef struct _HV_REFERENCE_TSC_PAGE {
 	__u32 tsc_sequence;
 	__u32 res1;
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 7df29f0..1e5f7a0 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -17,6 +17,7 @@
 #include <linux/irq.h>
 #include <linux/kexec.h>
 #include <linux/i8253.h>
+#include <linux/random.h>
 #include <asm/processor.h>
 #include <asm/hypervisor.h>
 #include <asm/hyperv-tlfs.h>
@@ -80,6 +81,7 @@ __visible void __irq_entry hv_stimer0_vector_handler(struct pt_regs *regs)
 	inc_irq_stat(hyperv_stimer0_count);
 	if (hv_stimer0_handler)
 		hv_stimer0_handler();
+	add_interrupt_randomness(HYPERV_STIMER0_VECTOR, 0);
 	ack_APIC_irq();
 
 	exiting_irq();
@@ -89,7 +91,7 @@ __visible void __irq_entry hv_stimer0_vector_handler(struct pt_regs *regs)
 int hv_setup_stimer0_irq(int *irq, int *vector, void (*handler)(void))
 {
 	*vector = HYPERV_STIMER0_VECTOR;
-	*irq = 0;   /* Unused on x86/x64 */
+	*irq = -1;   /* Unused on x86/x64 */
 	hv_stimer0_handler = handler;
 	return 0;
 }
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 236858f..2b65c5f 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -84,3 +84,4 @@ obj-$(CONFIG_ATCPIT100_TIMER)		+= timer-atcpit100.o
 obj-$(CONFIG_RISCV_TIMER)		+= timer-riscv.o
 obj-$(CONFIG_CSKY_MP_TIMER)		+= timer-mp-csky.o
 obj-$(CONFIG_GX6605S_TIMER)		+= timer-gx6605s.o
+obj-$(CONFIG_HYPERV_TIMER)		+= hyperv_timer.o
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
new file mode 100644
index 0000000..68a28af
--- /dev/null
+++ b/drivers/clocksource/hyperv_timer.c
@@ -0,0 +1,200 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Clocksource driver for the synthetic counter and timers
+ * provided by the Hyper-V hypervisor to guest VMs, as described
+ * in the Hyper-V Top Level Functional Spec (TLFS). This driver
+ * is instruction set architecture independent.
+ *
+ * Copyright (C) 2019, Microsoft, Inc.
+ *
+ * Author:  Michael Kelley <mikelley@microsoft.com>
+ */
+
+#include <linux/percpu.h>
+#include <linux/cpumask.h>
+#include <linux/clockchips.h>
+#include <linux/mm.h>
+#include <clocksource/hyperv_timer.h>
+#include <asm/hyperv-tlfs.h>
+#include <asm/mshyperv.h>
+
+static struct clock_event_device __percpu *hv_clock_event;
+
+/*
+ * If false, we're using the old mechanism for stimer0 interrupts
+ * where it sends a VMbus message when it expires. The old
+ * mechanism is used when running on older versions of Hyper-V
+ * that don't support Direct Mode. While Hyper-V provides
+ * four stimer's per CPU, Linux uses only stimer0.
+ */
+static bool direct_mode_enabled;
+
+static int stimer0_irq;
+static int stimer0_vector;
+static int stimer0_message_sint;
+
+/*
+ * ISR for when stimer0 is operating in Direct Mode.  Direct Mode
+ * does not use VMbus or any VMbus messages, so process here and not
+ * in the VMbus driver code.
+ */
+void hv_stimer0_isr(void)
+{
+	struct clock_event_device *ce;
+
+	ce = this_cpu_ptr(hv_clock_event);
+	ce->event_handler(ce);
+}
+EXPORT_SYMBOL_GPL(hv_stimer0_isr);
+
+static int hv_ce_set_next_event(unsigned long delta,
+				struct clock_event_device *evt)
+{
+	u64 current_tick;
+
+	current_tick = hyperv_cs->read(NULL);
+	current_tick += delta;
+	hv_init_timer(0, current_tick);
+	return 0;
+}
+
+static int hv_ce_shutdown(struct clock_event_device *evt)
+{
+	hv_init_timer(0, 0);
+	hv_init_timer_config(0, 0);
+	if (direct_mode_enabled)
+		hv_disable_stimer0_percpu_irq(stimer0_irq);
+
+	return 0;
+}
+
+static int hv_ce_set_oneshot(struct clock_event_device *evt)
+{
+	union hv_stimer_config timer_cfg;
+
+	timer_cfg.as_uint64 = 0;
+	timer_cfg.enable = 1;
+	timer_cfg.auto_enable = 1;
+	if (direct_mode_enabled) {
+		/*
+		 * When it expires, the timer will directly interrupt
+		 * on the specified hardware vector/IRQ.
+		 */
+		timer_cfg.direct_mode = 1;
+		timer_cfg.apic_vector = stimer0_vector;
+		hv_enable_stimer0_percpu_irq(stimer0_irq);
+	} else {
+		/*
+		 * When it expires, the timer will generate a VMbus message,
+		 * to be handled by the normal VMbus interrupt handler.
+		 */
+		timer_cfg.direct_mode = 0;
+		timer_cfg.sintx = stimer0_message_sint;
+	}
+	hv_init_timer_config(0, timer_cfg.as_uint64);
+	return 0;
+}
+
+/*
+ * hv_stimer_init - Per-cpu initialization of the clockevent
+ */
+void hv_stimer_init(unsigned int cpu)
+{
+	struct clock_event_device *ce;
+
+	/*
+	 * Synthetic timers are always available except on old versions of
+	 * Hyper-V on x86.  In that case, just return as Linux will use a
+	 * clocksource based on emulated PIT or LAPIC timer hardware.
+	 */
+	if (!(ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE))
+		return;
+
+	ce = per_cpu_ptr(hv_clock_event, cpu);
+	ce->name = "Hyper-V clockevent";
+	ce->features = CLOCK_EVT_FEAT_ONESHOT;
+	ce->cpumask = cpumask_of(cpu);
+	ce->rating = 1000;
+	ce->set_state_shutdown = hv_ce_shutdown;
+	ce->set_state_oneshot = hv_ce_set_oneshot;
+	ce->set_next_event = hv_ce_set_next_event;
+
+	clockevents_config_and_register(ce,
+					HV_CLOCK_HZ,
+					HV_MIN_DELTA_TICKS,
+					HV_MAX_MAX_DELTA_TICKS);
+}
+EXPORT_SYMBOL_GPL(hv_stimer_init);
+
+/*
+ * hv_stimer_cleanup - Per-cpu cleanup of the clockevent
+ */
+void hv_stimer_cleanup(unsigned int cpu)
+{
+	struct clock_event_device *ce;
+
+	/* Turn off clockevent device */
+	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
+		ce = per_cpu_ptr(hv_clock_event, cpu);
+		hv_ce_shutdown(ce);
+	}
+}
+EXPORT_SYMBOL_GPL(hv_stimer_cleanup);
+
+/* hv_stimer_alloc - Global initialization of the clockevent and stimer0 */
+int hv_stimer_alloc(int sint)
+{
+	int ret;
+
+	hv_clock_event = alloc_percpu(struct clock_event_device);
+	if (!hv_clock_event)
+		return -ENOMEM;
+
+	direct_mode_enabled = ms_hyperv.misc_features &
+			HV_STIMER_DIRECT_MODE_AVAILABLE;
+	if (direct_mode_enabled) {
+		ret = hv_setup_stimer0_irq(&stimer0_irq, &stimer0_vector,
+				hv_stimer0_isr);
+		if (ret) {
+			free_percpu(hv_clock_event);
+			hv_clock_event = NULL;
+			return ret;
+		}
+	}
+
+	stimer0_message_sint = sint;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hv_stimer_alloc);
+
+/* hv_stimer_free - Free global resources allocated by hv_stimer_alloc() */
+void hv_stimer_free(void)
+{
+	if (direct_mode_enabled && (stimer0_irq != 0)) {
+		hv_remove_stimer0_irq(stimer0_irq);
+		stimer0_irq = 0;
+	}
+	free_percpu(hv_clock_event);
+	hv_clock_event = NULL;
+}
+EXPORT_SYMBOL_GPL(hv_stimer_free);
+
+/*
+ * Do a global cleanup of clockevents for the cases of kexec and
+ * vmbus exit
+ */
+void hv_stimer_global_cleanup(void)
+{
+	int	cpu;
+	struct clock_event_device *ce;
+
+	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
+		for_each_present_cpu(cpu) {
+			ce = per_cpu_ptr(hv_clock_event, cpu);
+			clockevents_unbind_device(ce, cpu);
+		}
+	}
+	hv_stimer_free();
+}
+EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 1c1a251..c423e57 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -10,6 +10,9 @@ config HYPERV
 	  Select this option to run Linux as a Hyper-V client operating
 	  system.
 
+config HYPERV_TIMER
+	def_bool HYPERV
+
 config HYPERV_TSCPAGE
        def_bool HYPERV && X86_64
 
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index a1ea482..6188fb7 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -16,6 +16,7 @@
 #include <linux/version.h>
 #include <linux/random.h>
 #include <linux/clockchips.h>
+#include <clocksource/hyperv_timer.h>
 #include <asm/mshyperv.h>
 #include "hyperv_vmbus.h"
 
@@ -23,21 +24,6 @@
 struct hv_context hv_context;
 
 /*
- * If false, we're using the old mechanism for stimer0 interrupts
- * where it sends a VMbus message when it expires. The old
- * mechanism is used when running on older versions of Hyper-V
- * that don't support Direct Mode. While Hyper-V provides
- * four stimer's per CPU, Linux uses only stimer0.
- */
-static bool direct_mode_enabled;
-static int stimer0_irq;
-static int stimer0_vector;
-
-#define HV_TIMER_FREQUENCY (10 * 1000 * 1000) /* 100ns period */
-#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
-#define HV_MIN_DELTA_TICKS 1
-
-/*
  * hv_init - Main initialization routine.
  *
  * This routine must be called before any other routines in here are called
@@ -47,9 +33,6 @@ int hv_init(void)
 	hv_context.cpu_context = alloc_percpu(struct hv_per_cpu_context);
 	if (!hv_context.cpu_context)
 		return -ENOMEM;
-
-	direct_mode_enabled = ms_hyperv.misc_features &
-			HV_STIMER_DIRECT_MODE_AVAILABLE;
 	return 0;
 }
 
@@ -88,89 +71,6 @@ int hv_post_message(union hv_connection_id connection_id,
 	return status & 0xFFFF;
 }
 
-/*
- * ISR for when stimer0 is operating in Direct Mode.  Direct Mode
- * does not use VMbus or any VMbus messages, so process here and not
- * in the VMbus driver code.
- */
-
-static void hv_stimer0_isr(void)
-{
-	struct hv_per_cpu_context *hv_cpu;
-
-	hv_cpu = this_cpu_ptr(hv_context.cpu_context);
-	hv_cpu->clk_evt->event_handler(hv_cpu->clk_evt);
-	add_interrupt_randomness(stimer0_vector, 0);
-}
-
-static int hv_ce_set_next_event(unsigned long delta,
-				struct clock_event_device *evt)
-{
-	u64 current_tick;
-
-	WARN_ON(!clockevent_state_oneshot(evt));
-
-	current_tick = hyperv_cs->read(NULL);
-	current_tick += delta;
-	hv_init_timer(0, current_tick);
-	return 0;
-}
-
-static int hv_ce_shutdown(struct clock_event_device *evt)
-{
-	hv_init_timer(0, 0);
-	hv_init_timer_config(0, 0);
-	if (direct_mode_enabled)
-		hv_disable_stimer0_percpu_irq(stimer0_irq);
-
-	return 0;
-}
-
-static int hv_ce_set_oneshot(struct clock_event_device *evt)
-{
-	union hv_stimer_config timer_cfg;
-
-	timer_cfg.as_uint64 = 0;
-	timer_cfg.enable = 1;
-	timer_cfg.auto_enable = 1;
-	if (direct_mode_enabled) {
-		/*
-		 * When it expires, the timer will directly interrupt
-		 * on the specified hardware vector/IRQ.
-		 */
-		timer_cfg.direct_mode = 1;
-		timer_cfg.apic_vector = stimer0_vector;
-		hv_enable_stimer0_percpu_irq(stimer0_irq);
-	} else {
-		/*
-		 * When it expires, the timer will generate a VMbus message,
-		 * to be handled by the normal VMbus interrupt handler.
-		 */
-		timer_cfg.direct_mode = 0;
-		timer_cfg.sintx = VMBUS_MESSAGE_SINT;
-	}
-	hv_init_timer_config(0, timer_cfg.as_uint64);
-	return 0;
-}
-
-static void hv_init_clockevent_device(struct clock_event_device *dev, int cpu)
-{
-	dev->name = "Hyper-V clockevent";
-	dev->features = CLOCK_EVT_FEAT_ONESHOT;
-	dev->cpumask = cpumask_of(cpu);
-	dev->rating = 1000;
-	/*
-	 * Avoid settint dev->owner = THIS_MODULE deliberately as doing so will
-	 * result in clockevents_config_and_register() taking additional
-	 * references to the hv_vmbus module making it impossible to unload.
-	 */
-
-	dev->set_state_shutdown = hv_ce_shutdown;
-	dev->set_state_oneshot = hv_ce_set_oneshot;
-	dev->set_next_event = hv_ce_set_next_event;
-}
-
-
 int hv_synic_alloc(void)
 {
 	int cpu;
@@ -199,14 +99,6 @@ int hv_synic_alloc(void)
 		tasklet_init(&hv_cpu->msg_dpc,
 			     vmbus_on_msg_dpc, (unsigned long) hv_cpu);
 
-		hv_cpu->clk_evt = kzalloc(sizeof(struct clock_event_device),
-					  GFP_KERNEL);
-		if (hv_cpu->clk_evt == NULL) {
-			pr_err("Unable to allocate clock event device\n");
-			goto err;
-		}
-		hv_init_clockevent_device(hv_cpu->clk_evt, cpu);
-
 		hv_cpu->synic_message_page =
 			(void *)get_zeroed_page(GFP_ATOMIC);
 		if (hv_cpu->synic_message_page == NULL) {
@@ -229,11 +121,6 @@ int hv_synic_alloc(void)
 		INIT_LIST_HEAD(&hv_cpu->chan_list);
 	}
 
-	if (direct_mode_enabled &&
-	    hv_setup_stimer0_irq(&stimer0_irq, &stimer0_vector,
-				hv_stimer0_isr))
-		goto err;
-
 	return 0;
 err:
 	/*
@@ -252,7 +139,6 @@ void hv_synic_free(void)
 		struct hv_per_cpu_context *hv_cpu
 			= per_cpu_ptr(hv_context.cpu_context, cpu);
 
-		kfree(hv_cpu->clk_evt);
 		free_page((unsigned long)hv_cpu->synic_event_page);
 		free_page((unsigned long)hv_cpu->synic_message_page);
 		free_page((unsigned long)hv_cpu->post_msg_page);
@@ -311,36 +197,9 @@ int hv_synic_init(unsigned int cpu)
 
 	hv_set_synic_state(sctrl.as_uint64);
 
-	/*
-	 * Register the per-cpu clockevent source.
-	 */
-	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE)
-		clockevents_config_and_register(hv_cpu->clk_evt,
-						HV_TIMER_FREQUENCY,
-						HV_MIN_DELTA_TICKS,
-						HV_MAX_MAX_DELTA_TICKS);
-	return 0;
-}
-
-/*
- * hv_synic_clockevents_cleanup - Cleanup clockevent devices
- */
-void hv_synic_clockevents_cleanup(void)
-{
-	int cpu;
+	hv_stimer_init(cpu);
 
-	if (!(ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE))
-		return;
-
-	if (direct_mode_enabled)
-		hv_remove_stimer0_irq(stimer0_irq);
-
-	for_each_present_cpu(cpu) {
-		struct hv_per_cpu_context *hv_cpu
-			= per_cpu_ptr(hv_context.cpu_context, cpu);
-
-		clockevents_unbind_device(hv_cpu->clk_evt, cpu);
-	}
+	return 0;
 }
 
 /*
@@ -388,14 +247,7 @@ int hv_synic_cleanup(unsigned int cpu)
 	if (channel_found && vmbus_connection.conn_state == CONNECTED)
 		return -EBUSY;
 
-	/* Turn off clockevent device */
-	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
-		struct hv_per_cpu_context *hv_cpu
-			= this_cpu_ptr(hv_context.cpu_context);
-
-		clockevents_unbind_device(hv_cpu->clk_evt, cpu);
-		hv_ce_shutdown(hv_cpu->clk_evt);
-	}
+	hv_stimer_cleanup(cpu);
 
 	hv_get_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index b8e1ff0..362e70e 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -138,7 +138,6 @@ struct hv_per_cpu_context {
 	 * per-cpu list of the channels based on their CPU affinity.
 	 */
 	struct list_head chan_list;
-	struct clock_event_device *clk_evt;
 };
 
 struct hv_context {
@@ -176,8 +175,6 @@ extern int hv_post_message(union hv_connection_id connection_id,
 
 extern int hv_synic_cleanup(unsigned int cpu);
 
-extern void hv_synic_clockevents_cleanup(void);
-
 /* Interface */
 
 void hv_ringbuffer_pre_init(struct vmbus_channel *channel);
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 92b1874..72d5a7c 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -30,6 +30,7 @@
 #include <linux/kdebug.h>
 #include <linux/efi.h>
 #include <linux/random.h>
+#include <clocksource/hyperv_timer.h>
 #include "hyperv_vmbus.h"
 
 struct vmbus_dynid {
@@ -955,17 +956,6 @@ static void vmbus_onmessage_work(struct work_struct *work)
 	kfree(ctx);
 }
 
-static void hv_process_timer_expiration(struct hv_message *msg,
-					struct hv_per_cpu_context *hv_cpu)
-{
-	struct clock_event_device *dev = hv_cpu->clk_evt;
-
-	if (dev->event_handler)
-		dev->event_handler(dev);
-
-	vmbus_signal_eom(msg, HVMSG_TIMER_EXPIRED);
-}
-
 void vmbus_on_msg_dpc(unsigned long data)
 {
 	struct hv_per_cpu_context *hv_cpu = (void *)data;
@@ -1159,9 +1149,10 @@ static void vmbus_isr(void)
 
 	/* Check if there are actual msgs to be processed */
 	if (msg->header.message_type != HVMSG_NONE) {
-		if (msg->header.message_type == HVMSG_TIMER_EXPIRED)
-			hv_process_timer_expiration(msg, hv_cpu);
-		else
+		if (msg->header.message_type == HVMSG_TIMER_EXPIRED) {
+			hv_stimer0_isr();
+			vmbus_signal_eom(msg, HVMSG_TIMER_EXPIRED);
+		} else
 			tasklet_schedule(&hv_cpu->msg_dpc);
 	}
 
@@ -1263,14 +1254,19 @@ static int vmbus_bus_init(void)
 	ret = hv_synic_alloc();
 	if (ret)
 		goto err_alloc;
+
+	ret = hv_stimer_alloc(VMBUS_MESSAGE_SINT);
+	if (ret < 0)
+		goto err_alloc;
+
 	/*
-	 * Initialize the per-cpu interrupt state and
-	 * connect to the host.
+	 * Initialize the per-cpu interrupt state and stimer state.
+	 * Then connect to the host.
 	 */
 	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hyperv/vmbus:online",
 				hv_synic_init, hv_synic_cleanup);
 	if (ret < 0)
-		goto err_alloc;
+		goto err_cpuhp;
 	hyperv_cpuhp_online = ret;
 
 	ret = vmbus_connect();
@@ -1318,6 +1314,8 @@ static int vmbus_bus_init(void)
 
 err_connect:
 	cpuhp_remove_state(hyperv_cpuhp_online);
+err_cpuhp:
+	hv_stimer_free();
 err_alloc:
 	hv_synic_free();
 	hv_remove_vmbus_irq();
@@ -2064,7 +2062,7 @@ static int vmbus_acpi_add(struct acpi_device *device)
 
 static void hv_kexec_handler(void)
 {
-	hv_synic_clockevents_cleanup();
+	hv_stimer_global_cleanup();
 	vmbus_initiate_unload(false);
 	vmbus_connection.conn_state = DISCONNECTED;
 	/* Make sure conn_state is set as hv_synic_cleanup checks for it */
@@ -2075,6 +2073,8 @@ static void hv_kexec_handler(void)
 
 static void hv_crash_handler(struct pt_regs *regs)
 {
+	int cpu;
+
 	vmbus_initiate_unload(true);
 	/*
 	 * In crash handler we can't schedule synic cleanup for all CPUs,
@@ -2082,7 +2082,9 @@ static void hv_crash_handler(struct pt_regs *regs)
 	 * for kdump.
 	 */
 	vmbus_connection.conn_state = DISCONNECTED;
-	hv_synic_cleanup(smp_processor_id());
+	cpu = smp_processor_id();
+	hv_stimer_cleanup(cpu);
+	hv_synic_cleanup(cpu);
 	hyperv_cleanup();
 };
 
@@ -2131,7 +2133,7 @@ static void __exit vmbus_exit(void)
 	hv_remove_kexec_handler();
 	hv_remove_crash_handler();
 	vmbus_connection.conn_state = DISCONNECTED;
-	hv_synic_clockevents_cleanup();
+	hv_stimer_global_cleanup();
 	vmbus_disconnect();
 	hv_remove_vmbus_irq();
 	for_each_online_cpu(cpu) {
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
new file mode 100644
index 0000000..0cd73f7
--- /dev/null
+++ b/include/clocksource/hyperv_timer.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Definitions for the clocksource provided by the Hyper-V
+ * hypervisor to guest VMs, as described in the Hyper-V Top
+ * Level Functional Spec (TLFS).
+ *
+ * Copyright (C) 2019, Microsoft, Inc.
+ *
+ * Author:  Michael Kelley <mikelley@microsoft.com>
+ */
+
+#ifndef __CLKSOURCE_HYPERV_TIMER_H
+#define __CLKSOURCE_HYPERV_TIMER_H
+
+#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
+#define HV_MIN_DELTA_TICKS 1
+
+/* Routines called by the VMbus driver */
+extern int hv_stimer_alloc(int sint);
+extern void hv_stimer_free(void);
+extern void hv_stimer_init(unsigned int cpu);
+extern void hv_stimer_cleanup(unsigned int cpu);
+extern void hv_stimer_global_cleanup(void);
+extern void hv_stimer0_isr(void);
+
+#endif
-- 
1.8.3.1

[PATCH v5 1/2] clocksource/drivers: Make Hyper-V clocksource ISA agnostic

[Michael Kelley]

Hyper-V clock/timer code and data structures are currently mixed
in with other code in the ISA independent drivers/hv directory as
well as the ISA dependent Hyper-V code under arch/x86.  Consolidate
this code and data structures into a Hyper-V clocksource driver to
better follow the Linux model. In doing so, separate out the ISA
dependent portions so the new clocksource driver works for x86 and
for the in-process Hyper-V on ARM64 code.

To start, move the existing clockevents code to create the
new clocksource driver. Update the VMbus driver to call
initialization and cleanup routines since the Hyper-V
synthetic timers are not independently enumerated in ACPI.

No behavior is changed and no new functionality is added.

Suggested-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
---
 MAINTAINERS                        |   2 +
 arch/x86/include/asm/hyperv-tlfs.h |   6 ++
 arch/x86/kernel/cpu/mshyperv.c     |   4 +-
 drivers/clocksource/Makefile       |   1 +
 drivers/clocksource/hyperv_timer.c | 200 +++++++++++++++++++++++++++++++++++++
 drivers/hv/Kconfig                 |   3 +
 drivers/hv/hv.c                    | 156 +----------------------------
 drivers/hv/hyperv_vmbus.h          |   3 -
 drivers/hv/vmbus_drv.c             |  42 ++++----
 include/clocksource/hyperv_timer.h |  27 +++++
 10 files changed, 268 insertions(+), 176 deletions(-)
 create mode 100644 drivers/clocksource/hyperv_timer.c
 create mode 100644 include/clocksource/hyperv_timer.h

diff --git a/MAINTAINERS b/MAINTAINERS
index a281297..bfde42a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7313,6 +7313,7 @@ F:	arch/x86/include/asm/trace/hyperv.h
 F:	arch/x86/include/asm/hyperv-tlfs.h
 F:	arch/x86/kernel/cpu/mshyperv.c
 F:	arch/x86/hyperv
+F:	drivers/clocksource/hyperv_timer.c
 F:	drivers/hid/hid-hyperv.c
 F:	drivers/hv/
 F:	drivers/input/serio/hyperv-keyboard.c
@@ -7323,6 +7324,7 @@ F:	drivers/uio/uio_hv_generic.c
 F:	drivers/video/fbdev/hyperv_fb.c
 F:	drivers/iommu/hyperv_iommu.c
 F:	net/vmw_vsock/hyperv_transport.c
+F:	include/clocksource/hyperv_timer.h
 F:	include/linux/hyperv.h
 F:	include/uapi/linux/hyperv.h
 F:	tools/hv/
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index cdf44aa..af78cd7 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -401,6 +401,12 @@ enum HV_GENERIC_SET_FORMAT {
 #define HV_STATUS_INVALID_CONNECTION_ID		18
 #define HV_STATUS_INSUFFICIENT_BUFFERS		19
 
+/*
+ * The Hyper-V TimeRefCount register and the TSC
+ * page provide a guest VM clock with 100ns tick rate
+ */
+#define HV_CLOCK_HZ (NSEC_PER_SEC/100)
+
 typedef struct _HV_REFERENCE_TSC_PAGE {
 	__u32 tsc_sequence;
 	__u32 res1;
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 7df29f0..1e5f7a0 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -17,6 +17,7 @@
 #include <linux/irq.h>
 #include <linux/kexec.h>
 #include <linux/i8253.h>
+#include <linux/random.h>
 #include <asm/processor.h>
 #include <asm/hypervisor.h>
 #include <asm/hyperv-tlfs.h>
@@ -80,6 +81,7 @@ __visible void __irq_entry hv_stimer0_vector_handler(struct pt_regs *regs)
 	inc_irq_stat(hyperv_stimer0_count);
 	if (hv_stimer0_handler)
 		hv_stimer0_handler();
+	add_interrupt_randomness(HYPERV_STIMER0_VECTOR, 0);
 	ack_APIC_irq();
 
 	exiting_irq();
@@ -89,7 +91,7 @@ __visible void __irq_entry hv_stimer0_vector_handler(struct pt_regs *regs)
 int hv_setup_stimer0_irq(int *irq, int *vector, void (*handler)(void))
 {
 	*vector = HYPERV_STIMER0_VECTOR;
-	*irq = 0;   /* Unused on x86/x64 */
+	*irq = -1;   /* Unused on x86/x64 */
 	hv_stimer0_handler = handler;
 	return 0;
 }
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 236858f..2b65c5f 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -84,3 +84,4 @@ obj-$(CONFIG_ATCPIT100_TIMER)		+= timer-atcpit100.o
 obj-$(CONFIG_RISCV_TIMER)		+= timer-riscv.o
 obj-$(CONFIG_CSKY_MP_TIMER)		+= timer-mp-csky.o
 obj-$(CONFIG_GX6605S_TIMER)		+= timer-gx6605s.o
+obj-$(CONFIG_HYPERV_TIMER)		+= hyperv_timer.o
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
new file mode 100644
index 0000000..68a28af
--- /dev/null
+++ b/drivers/clocksource/hyperv_timer.c
@@ -0,0 +1,200 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Clocksource driver for the synthetic counter and timers
+ * provided by the Hyper-V hypervisor to guest VMs, as described
+ * in the Hyper-V Top Level Functional Spec (TLFS). This driver
+ * is instruction set architecture independent.
+ *
+ * Copyright (C) 2019, Microsoft, Inc.
+ *
+ * Author:  Michael Kelley <mikelley@microsoft.com>
+ */
+
+#include <linux/percpu.h>
+#include <linux/cpumask.h>
+#include <linux/clockchips.h>
+#include <linux/mm.h>
+#include <clocksource/hyperv_timer.h>
+#include <asm/hyperv-tlfs.h>
+#include <asm/mshyperv.h>
+
+static struct clock_event_device __percpu *hv_clock_event;
+
+/*
+ * If false, we're using the old mechanism for stimer0 interrupts
+ * where it sends a VMbus message when it expires. The old
+ * mechanism is used when running on older versions of Hyper-V
+ * that don't support Direct Mode. While Hyper-V provides
+ * four stimer's per CPU, Linux uses only stimer0.
+ */
+static bool direct_mode_enabled;
+
+static int stimer0_irq;
+static int stimer0_vector;
+static int stimer0_message_sint;
+
+/*
+ * ISR for when stimer0 is operating in Direct Mode.  Direct Mode
+ * does not use VMbus or any VMbus messages, so process here and not
+ * in the VMbus driver code.
+ */
+void hv_stimer0_isr(void)
+{
+	struct clock_event_device *ce;
+
+	ce = this_cpu_ptr(hv_clock_event);
+	ce->event_handler(ce);
+}
+EXPORT_SYMBOL_GPL(hv_stimer0_isr);
+
+static int hv_ce_set_next_event(unsigned long delta,
+				struct clock_event_device *evt)
+{
+	u64 current_tick;
+
+	current_tick = hyperv_cs->read(NULL);
+	current_tick += delta;
+	hv_init_timer(0, current_tick);
+	return 0;
+}
+
+static int hv_ce_shutdown(struct clock_event_device *evt)
+{
+	hv_init_timer(0, 0);
+	hv_init_timer_config(0, 0);
+	if (direct_mode_enabled)
+		hv_disable_stimer0_percpu_irq(stimer0_irq);
+
+	return 0;
+}
+
+static int hv_ce_set_oneshot(struct clock_event_device *evt)
+{
+	union hv_stimer_config timer_cfg;
+
+	timer_cfg.as_uint64 = 0;
+	timer_cfg.enable = 1;
+	timer_cfg.auto_enable = 1;
+	if (direct_mode_enabled) {
+		/*
+		 * When it expires, the timer will directly interrupt
+		 * on the specified hardware vector/IRQ.
+		 */
+		timer_cfg.direct_mode = 1;
+		timer_cfg.apic_vector = stimer0_vector;
+		hv_enable_stimer0_percpu_irq(stimer0_irq);
+	} else {
+		/*
+		 * When it expires, the timer will generate a VMbus message,
+		 * to be handled by the normal VMbus interrupt handler.
+		 */
+		timer_cfg.direct_mode = 0;
+		timer_cfg.sintx = stimer0_message_sint;
+	}
+	hv_init_timer_config(0, timer_cfg.as_uint64);
+	return 0;
+}
+
+/*
+ * hv_stimer_init - Per-cpu initialization of the clockevent
+ */
+void hv_stimer_init(unsigned int cpu)
+{
+	struct clock_event_device *ce;
+
+	/*
+	 * Synthetic timers are always available except on old versions of
+	 * Hyper-V on x86.  In that case, just return as Linux will use a
+	 * clocksource based on emulated PIT or LAPIC timer hardware.
+	 */
+	if (!(ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE))
+		return;
+
+	ce = per_cpu_ptr(hv_clock_event, cpu);
+	ce->name = "Hyper-V clockevent";
+	ce->features = CLOCK_EVT_FEAT_ONESHOT;
+	ce->cpumask = cpumask_of(cpu);
+	ce->rating = 1000;
+	ce->set_state_shutdown = hv_ce_shutdown;
+	ce->set_state_oneshot = hv_ce_set_oneshot;
+	ce->set_next_event = hv_ce_set_next_event;
+
+	clockevents_config_and_register(ce,
+					HV_CLOCK_HZ,
+					HV_MIN_DELTA_TICKS,
+					HV_MAX_MAX_DELTA_TICKS);
+}
+EXPORT_SYMBOL_GPL(hv_stimer_init);
+
+/*
+ * hv_stimer_cleanup - Per-cpu cleanup of the clockevent
+ */
+void hv_stimer_cleanup(unsigned int cpu)
+{
+	struct clock_event_device *ce;
+
+	/* Turn off clockevent device */
+	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
+		ce = per_cpu_ptr(hv_clock_event, cpu);
+		hv_ce_shutdown(ce);
+	}
+}
+EXPORT_SYMBOL_GPL(hv_stimer_cleanup);
+
+/* hv_stimer_alloc - Global initialization of the clockevent and stimer0 */
+int hv_stimer_alloc(int sint)
+{
+	int ret;
+
+	hv_clock_event = alloc_percpu(struct clock_event_device);
+	if (!hv_clock_event)
+		return -ENOMEM;
+
+	direct_mode_enabled = ms_hyperv.misc_features &
+			HV_STIMER_DIRECT_MODE_AVAILABLE;
+	if (direct_mode_enabled) {
+		ret = hv_setup_stimer0_irq(&stimer0_irq, &stimer0_vector,
+				hv_stimer0_isr);
+		if (ret) {
+			free_percpu(hv_clock_event);
+			hv_clock_event = NULL;
+			return ret;
+		}
+	}
+
+	stimer0_message_sint = sint;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hv_stimer_alloc);
+
+/* hv_stimer_free - Free global resources allocated by hv_stimer_alloc() */
+void hv_stimer_free(void)
+{
+	if (direct_mode_enabled && (stimer0_irq != 0)) {
+		hv_remove_stimer0_irq(stimer0_irq);
+		stimer0_irq = 0;
+	}
+	free_percpu(hv_clock_event);
+	hv_clock_event = NULL;
+}
+EXPORT_SYMBOL_GPL(hv_stimer_free);
+
+/*
+ * Do a global cleanup of clockevents for the cases of kexec and
+ * vmbus exit
+ */
+void hv_stimer_global_cleanup(void)
+{
+	int	cpu;
+	struct clock_event_device *ce;
+
+	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
+		for_each_present_cpu(cpu) {
+			ce = per_cpu_ptr(hv_clock_event, cpu);
+			clockevents_unbind_device(ce, cpu);
+		}
+	}
+	hv_stimer_free();
+}
+EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 1c1a251..c423e57 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -10,6 +10,9 @@ config HYPERV
 	  Select this option to run Linux as a Hyper-V client operating
 	  system.
 
+config HYPERV_TIMER
+	def_bool HYPERV
+
 config HYPERV_TSCPAGE
        def_bool HYPERV && X86_64
 
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index a1ea482..6188fb7 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -16,6 +16,7 @@
 #include <linux/version.h>
 #include <linux/random.h>
 #include <linux/clockchips.h>
+#include <clocksource/hyperv_timer.h>
 #include <asm/mshyperv.h>
 #include "hyperv_vmbus.h"
 
@@ -23,21 +24,6 @@
 struct hv_context hv_context;
 
 /*
- * If false, we're using the old mechanism for stimer0 interrupts
- * where it sends a VMbus message when it expires. The old
- * mechanism is used when running on older versions of Hyper-V
- * that don't support Direct Mode. While Hyper-V provides
- * four stimer's per CPU, Linux uses only stimer0.
- */
-static bool direct_mode_enabled;
-static int stimer0_irq;
-static int stimer0_vector;
-
-#define HV_TIMER_FREQUENCY (10 * 1000 * 1000) /* 100ns period */
-#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
-#define HV_MIN_DELTA_TICKS 1
-
-/*
  * hv_init - Main initialization routine.
  *
  * This routine must be called before any other routines in here are called
@@ -47,9 +33,6 @@ int hv_init(void)
 	hv_context.cpu_context = alloc_percpu(struct hv_per_cpu_context);
 	if (!hv_context.cpu_context)
 		return -ENOMEM;
-
-	direct_mode_enabled = ms_hyperv.misc_features &
-			HV_STIMER_DIRECT_MODE_AVAILABLE;
 	return 0;
 }
 
@@ -88,89 +71,6 @@ int hv_post_message(union hv_connection_id connection_id,
 	return status & 0xFFFF;
 }
 
-/*
- * ISR for when stimer0 is operating in Direct Mode.  Direct Mode
- * does not use VMbus or any VMbus messages, so process here and not
- * in the VMbus driver code.
- */
-
-static void hv_stimer0_isr(void)
-{
-	struct hv_per_cpu_context *hv_cpu;
-
-	hv_cpu = this_cpu_ptr(hv_context.cpu_context);
-	hv_cpu->clk_evt->event_handler(hv_cpu->clk_evt);
-	add_interrupt_randomness(stimer0_vector, 0);
-}
-
-static int hv_ce_set_next_event(unsigned long delta,
-				struct clock_event_device *evt)
-{
-	u64 current_tick;
-
-	WARN_ON(!clockevent_state_oneshot(evt));
-
-	current_tick = hyperv_cs->read(NULL);
-	current_tick += delta;
-	hv_init_timer(0, current_tick);
-	return 0;
-}
-
-static int hv_ce_shutdown(struct clock_event_device *evt)
-{
-	hv_init_timer(0, 0);
-	hv_init_timer_config(0, 0);
-	if (direct_mode_enabled)
-		hv_disable_stimer0_percpu_irq(stimer0_irq);
-
-	return 0;
-}
-
-static int hv_ce_set_oneshot(struct clock_event_device *evt)
-{
-	union hv_stimer_config timer_cfg;
-
-	timer_cfg.as_uint64 = 0;
-	timer_cfg.enable = 1;
-	timer_cfg.auto_enable = 1;
-	if (direct_mode_enabled) {
-		/*
-		 * When it expires, the timer will directly interrupt
-		 * on the specified hardware vector/IRQ.
-		 */
-		timer_cfg.direct_mode = 1;
-		timer_cfg.apic_vector = stimer0_vector;
-		hv_enable_stimer0_percpu_irq(stimer0_irq);
-	} else {
-		/*
-		 * When it expires, the timer will generate a VMbus message,
-		 * to be handled by the normal VMbus interrupt handler.
-		 */
-		timer_cfg.direct_mode = 0;
-		timer_cfg.sintx = VMBUS_MESSAGE_SINT;
-	}
-	hv_init_timer_config(0, timer_cfg.as_uint64);
-	return 0;
-}
-
-static void hv_init_clockevent_device(struct clock_event_device *dev, int cpu)
-{
-	dev->name = "Hyper-V clockevent";
-	dev->features = CLOCK_EVT_FEAT_ONESHOT;
-	dev->cpumask = cpumask_of(cpu);
-	dev->rating = 1000;
-	/*
-	 * Avoid settint dev->owner = THIS_MODULE deliberately as doing so will
-	 * result in clockevents_config_and_register() taking additional
-	 * references to the hv_vmbus module making it impossible to unload.
-	 */
-
-	dev->set_state_shutdown = hv_ce_shutdown;
-	dev->set_state_oneshot = hv_ce_set_oneshot;
-	dev->set_next_event = hv_ce_set_next_event;
-}
-
-
 int hv_synic_alloc(void)
 {
 	int cpu;
@@ -199,14 +99,6 @@ int hv_synic_alloc(void)
 		tasklet_init(&hv_cpu->msg_dpc,
 			     vmbus_on_msg_dpc, (unsigned long) hv_cpu);
 
-		hv_cpu->clk_evt = kzalloc(sizeof(struct clock_event_device),
-					  GFP_KERNEL);
-		if (hv_cpu->clk_evt == NULL) {
-			pr_err("Unable to allocate clock event device\n");
-			goto err;
-		}
-		hv_init_clockevent_device(hv_cpu->clk_evt, cpu);
-
 		hv_cpu->synic_message_page =
 			(void *)get_zeroed_page(GFP_ATOMIC);
 		if (hv_cpu->synic_message_page == NULL) {
@@ -229,11 +121,6 @@ int hv_synic_alloc(void)
 		INIT_LIST_HEAD(&hv_cpu->chan_list);
 	}
 
-	if (direct_mode_enabled &&
-	    hv_setup_stimer0_irq(&stimer0_irq, &stimer0_vector,
-				hv_stimer0_isr))
-		goto err;
-
 	return 0;
 err:
 	/*
@@ -252,7 +139,6 @@ void hv_synic_free(void)
 		struct hv_per_cpu_context *hv_cpu
 			= per_cpu_ptr(hv_context.cpu_context, cpu);
 
-		kfree(hv_cpu->clk_evt);
 		free_page((unsigned long)hv_cpu->synic_event_page);
 		free_page((unsigned long)hv_cpu->synic_message_page);
 		free_page((unsigned long)hv_cpu->post_msg_page);
@@ -311,36 +197,9 @@ int hv_synic_init(unsigned int cpu)
 
 	hv_set_synic_state(sctrl.as_uint64);
 
-	/*
-	 * Register the per-cpu clockevent source.
-	 */
-	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE)
-		clockevents_config_and_register(hv_cpu->clk_evt,
-						HV_TIMER_FREQUENCY,
-						HV_MIN_DELTA_TICKS,
-						HV_MAX_MAX_DELTA_TICKS);
-	return 0;
-}
-
-/*
- * hv_synic_clockevents_cleanup - Cleanup clockevent devices
- */
-void hv_synic_clockevents_cleanup(void)
-{
-	int cpu;
+	hv_stimer_init(cpu);
 
-	if (!(ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE))
-		return;
-
-	if (direct_mode_enabled)
-		hv_remove_stimer0_irq(stimer0_irq);
-
-	for_each_present_cpu(cpu) {
-		struct hv_per_cpu_context *hv_cpu
-			= per_cpu_ptr(hv_context.cpu_context, cpu);
-
-		clockevents_unbind_device(hv_cpu->clk_evt, cpu);
-	}
+	return 0;
 }
 
 /*
@@ -388,14 +247,7 @@ int hv_synic_cleanup(unsigned int cpu)
 	if (channel_found && vmbus_connection.conn_state == CONNECTED)
 		return -EBUSY;
 
-	/* Turn off clockevent device */
-	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
-		struct hv_per_cpu_context *hv_cpu
-			= this_cpu_ptr(hv_context.cpu_context);
-
-		clockevents_unbind_device(hv_cpu->clk_evt, cpu);
-		hv_ce_shutdown(hv_cpu->clk_evt);
-	}
+	hv_stimer_cleanup(cpu);
 
 	hv_get_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index b8e1ff0..362e70e 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -138,7 +138,6 @@ struct hv_per_cpu_context {
 	 * per-cpu list of the channels based on their CPU affinity.
 	 */
 	struct list_head chan_list;
-	struct clock_event_device *clk_evt;
 };
 
 struct hv_context {
@@ -176,8 +175,6 @@ extern int hv_post_message(union hv_connection_id connection_id,
 
 extern int hv_synic_cleanup(unsigned int cpu);
 
-extern void hv_synic_clockevents_cleanup(void);
-
 /* Interface */
 
 void hv_ringbuffer_pre_init(struct vmbus_channel *channel);
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 92b1874..72d5a7c 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -30,6 +30,7 @@
 #include <linux/kdebug.h>
 #include <linux/efi.h>
 #include <linux/random.h>
+#include <clocksource/hyperv_timer.h>
 #include "hyperv_vmbus.h"
 
 struct vmbus_dynid {
@@ -955,17 +956,6 @@ static void vmbus_onmessage_work(struct work_struct *work)
 	kfree(ctx);
 }
 
-static void hv_process_timer_expiration(struct hv_message *msg,
-					struct hv_per_cpu_context *hv_cpu)
-{
-	struct clock_event_device *dev = hv_cpu->clk_evt;
-
-	if (dev->event_handler)
-		dev->event_handler(dev);
-
-	vmbus_signal_eom(msg, HVMSG_TIMER_EXPIRED);
-}
-
 void vmbus_on_msg_dpc(unsigned long data)
 {
 	struct hv_per_cpu_context *hv_cpu = (void *)data;
@@ -1159,9 +1149,10 @@ static void vmbus_isr(void)
 
 	/* Check if there are actual msgs to be processed */
 	if (msg->header.message_type != HVMSG_NONE) {
-		if (msg->header.message_type == HVMSG_TIMER_EXPIRED)
-			hv_process_timer_expiration(msg, hv_cpu);
-		else
+		if (msg->header.message_type == HVMSG_TIMER_EXPIRED) {
+			hv_stimer0_isr();
+			vmbus_signal_eom(msg, HVMSG_TIMER_EXPIRED);
+		} else
 			tasklet_schedule(&hv_cpu->msg_dpc);
 	}
 
@@ -1263,14 +1254,19 @@ static int vmbus_bus_init(void)
 	ret = hv_synic_alloc();
 	if (ret)
 		goto err_alloc;
+
+	ret = hv_stimer_alloc(VMBUS_MESSAGE_SINT);
+	if (ret < 0)
+		goto err_alloc;
+
 	/*
-	 * Initialize the per-cpu interrupt state and
-	 * connect to the host.
+	 * Initialize the per-cpu interrupt state and stimer state.
+	 * Then connect to the host.
 	 */
 	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hyperv/vmbus:online",
 				hv_synic_init, hv_synic_cleanup);
 	if (ret < 0)
-		goto err_alloc;
+		goto err_cpuhp;
 	hyperv_cpuhp_online = ret;
 
 	ret = vmbus_connect();
@@ -1318,6 +1314,8 @@ static int vmbus_bus_init(void)
 
 err_connect:
 	cpuhp_remove_state(hyperv_cpuhp_online);
+err_cpuhp:
+	hv_stimer_free();
 err_alloc:
 	hv_synic_free();
 	hv_remove_vmbus_irq();
@@ -2064,7 +2062,7 @@ static int vmbus_acpi_add(struct acpi_device *device)
 
 static void hv_kexec_handler(void)
 {
-	hv_synic_clockevents_cleanup();
+	hv_stimer_global_cleanup();
 	vmbus_initiate_unload(false);
 	vmbus_connection.conn_state = DISCONNECTED;
 	/* Make sure conn_state is set as hv_synic_cleanup checks for it */
@@ -2075,6 +2073,8 @@ static void hv_kexec_handler(void)
 
 static void hv_crash_handler(struct pt_regs *regs)
 {
+	int cpu;
+
 	vmbus_initiate_unload(true);
 	/*
 	 * In crash handler we can't schedule synic cleanup for all CPUs,
@@ -2082,7 +2082,9 @@ static void hv_crash_handler(struct pt_regs *regs)
 	 * for kdump.
 	 */
 	vmbus_connection.conn_state = DISCONNECTED;
-	hv_synic_cleanup(smp_processor_id());
+	cpu = smp_processor_id();
+	hv_stimer_cleanup(cpu);
+	hv_synic_cleanup(cpu);
 	hyperv_cleanup();
 };
 
@@ -2131,7 +2133,7 @@ static void __exit vmbus_exit(void)
 	hv_remove_kexec_handler();
 	hv_remove_crash_handler();
 	vmbus_connection.conn_state = DISCONNECTED;
-	hv_synic_clockevents_cleanup();
+	hv_stimer_global_cleanup();
 	vmbus_disconnect();
 	hv_remove_vmbus_irq();
 	for_each_online_cpu(cpu) {
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
new file mode 100644
index 0000000..0cd73f7
--- /dev/null
+++ b/include/clocksource/hyperv_timer.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Definitions for the clocksource provided by the Hyper-V
+ * hypervisor to guest VMs, as described in the Hyper-V Top
+ * Level Functional Spec (TLFS).
+ *
+ * Copyright (C) 2019, Microsoft, Inc.
+ *
+ * Author:  Michael Kelley <mikelley@microsoft.com>
+ */
+
+#ifndef __CLKSOURCE_HYPERV_TIMER_H
+#define __CLKSOURCE_HYPERV_TIMER_H
+
+#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
+#define HV_MIN_DELTA_TICKS 1
+
+/* Routines called by the VMbus driver */
+extern int hv_stimer_alloc(int sint);
+extern void hv_stimer_free(void);
+extern void hv_stimer_init(unsigned int cpu);
+extern void hv_stimer_cleanup(unsigned int cpu);
+extern void hv_stimer_global_cleanup(void);
+extern void hv_stimer0_isr(void);
+
+#endif
-- 
1.8.3.1

[tip:timers/core] clocksource/drivers: Make Hyper-V clocksource ISA agnostic

[tip-bot for Michael Kelley]

Commit-ID:  fd1fea6834d0f9f93062ae6685862908a9baed39
Gitweb:     https://git.kernel.org/tip/fd1fea6834d0f9f93062ae6685862908a9baed39
Author:     Michael Kelley <mikelley@microsoft.com>
AuthorDate: Mon, 1 Jul 2019 04:25:56 +0000
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 3 Jul 2019 11:00:59 +0200

clocksource/drivers: Make Hyper-V clocksource ISA agnostic

Hyper-V clock/timer code and data structures are currently mixed
in with other code in the ISA independent drivers/hv directory as
well as the ISA dependent Hyper-V code under arch/x86.

Consolidate this code and data structures into a Hyper-V clocksource driver
to better follow the Linux model. In doing so, separate out the ISA
dependent portions so the new clocksource driver works for x86 and for the
in-process Hyper-V on ARM64 code.

To start, move the existing clockevents code to create the new clocksource
driver. Update the VMbus driver to call initialization and cleanup routines
since the Hyper-V synthetic timers are not independently enumerated in
ACPI.

No behavior is changed and no new functionality is added.

Suggested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: "bp@alien8.de" <bp@alien8.de>
Cc: "will.deacon@arm.com" <will.deacon@arm.com>
Cc: "catalin.marinas@arm.com" <catalin.marinas@arm.com>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>
Cc: "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Cc: "olaf@aepfle.de" <olaf@aepfle.de>
Cc: "apw@canonical.com" <apw@canonical.com>
Cc: "jasowang@redhat.com" <jasowang@redhat.com>
Cc: "marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>
Cc: Sunil Muthuswamy <sunilmut@microsoft.com>
Cc: KY Srinivasan <kys@microsoft.com>
Cc: "sashal@kernel.org" <sashal@kernel.org>
Cc: "vincenzo.frascino@arm.com" <vincenzo.frascino@arm.com>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Cc: "linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>
Cc: "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>
Cc: "arnd@arndb.de" <arnd@arndb.de>
Cc: "linux@armlinux.org.uk" <linux@armlinux.org.uk>
Cc: "ralf@linux-mips.org" <ralf@linux-mips.org>
Cc: "paul.burton@mips.com" <paul.burton@mips.com>
Cc: "daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>
Cc: "salyzyn@android.com" <salyzyn@android.com>
Cc: "pcc@google.com" <pcc@google.com>
Cc: "shuah@kernel.org" <shuah@kernel.org>
Cc: "0x7f454c46@gmail.com" <0x7f454c46@gmail.com>
Cc: "linux@rasmusvillemoes.dk" <linux@rasmusvillemoes.dk>
Cc: "huw@codeweavers.com" <huw@codeweavers.com>
Cc: "sfr@canb.auug.org.au" <sfr@canb.auug.org.au>
Cc: "pbonzini@redhat.com" <pbonzini@redhat.com>
Cc: "rkrcmar@redhat.com" <rkrcmar@redhat.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Link: https://lkml.kernel.org/r/1561955054-1838-2-git-send-email-mikelley@microsoft.com

---
 MAINTAINERS                        |   2 +
 arch/x86/include/asm/hyperv-tlfs.h |   6 ++
 arch/x86/kernel/cpu/mshyperv.c     |   4 +-
 drivers/clocksource/Makefile       |   1 +
 drivers/clocksource/hyperv_timer.c | 200 +++++++++++++++++++++++++++++++++++++
 drivers/hv/Kconfig                 |   3 +
 drivers/hv/hv.c                    | 156 +----------------------------
 drivers/hv/hyperv_vmbus.h          |   3 -
 drivers/hv/vmbus_drv.c             |  42 ++++----
 include/clocksource/hyperv_timer.h |  27 +++++
 10 files changed, 268 insertions(+), 176 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index a2812972b7b0..bfde42a76a95 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7313,6 +7313,7 @@ F:	arch/x86/include/asm/trace/hyperv.h
 F:	arch/x86/include/asm/hyperv-tlfs.h
 F:	arch/x86/kernel/cpu/mshyperv.c
 F:	arch/x86/hyperv
+F:	drivers/clocksource/hyperv_timer.c
 F:	drivers/hid/hid-hyperv.c
 F:	drivers/hv/
 F:	drivers/input/serio/hyperv-keyboard.c
@@ -7323,6 +7324,7 @@ F:	drivers/uio/uio_hv_generic.c
 F:	drivers/video/fbdev/hyperv_fb.c
 F:	drivers/iommu/hyperv_iommu.c
 F:	net/vmw_vsock/hyperv_transport.c
+F:	include/clocksource/hyperv_timer.h
 F:	include/linux/hyperv.h
 F:	include/uapi/linux/hyperv.h
 F:	tools/hv/
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index cdf44aa9a501..af78cd72b8f3 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -401,6 +401,12 @@ enum HV_GENERIC_SET_FORMAT {
 #define HV_STATUS_INVALID_CONNECTION_ID		18
 #define HV_STATUS_INSUFFICIENT_BUFFERS		19
 
+/*
+ * The Hyper-V TimeRefCount register and the TSC
+ * page provide a guest VM clock with 100ns tick rate
+ */
+#define HV_CLOCK_HZ (NSEC_PER_SEC/100)
+
 typedef struct _HV_REFERENCE_TSC_PAGE {
 	__u32 tsc_sequence;
 	__u32 res1;
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 7df29f08871b..1e5f7a03ddf5 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -17,6 +17,7 @@
 #include <linux/irq.h>
 #include <linux/kexec.h>
 #include <linux/i8253.h>
+#include <linux/random.h>
 #include <asm/processor.h>
 #include <asm/hypervisor.h>
 #include <asm/hyperv-tlfs.h>
@@ -80,6 +81,7 @@ __visible void __irq_entry hv_stimer0_vector_handler(struct pt_regs *regs)
 	inc_irq_stat(hyperv_stimer0_count);
 	if (hv_stimer0_handler)
 		hv_stimer0_handler();
+	add_interrupt_randomness(HYPERV_STIMER0_VECTOR, 0);
 	ack_APIC_irq();
 
 	exiting_irq();
@@ -89,7 +91,7 @@ __visible void __irq_entry hv_stimer0_vector_handler(struct pt_regs *regs)
 int hv_setup_stimer0_irq(int *irq, int *vector, void (*handler)(void))
 {
 	*vector = HYPERV_STIMER0_VECTOR;
-	*irq = 0;   /* Unused on x86/x64 */
+	*irq = -1;   /* Unused on x86/x64 */
 	hv_stimer0_handler = handler;
 	return 0;
 }
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 5582252efb31..2e7936e7833f 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -86,3 +86,4 @@ obj-$(CONFIG_ATCPIT100_TIMER)		+= timer-atcpit100.o
 obj-$(CONFIG_RISCV_TIMER)		+= timer-riscv.o
 obj-$(CONFIG_CSKY_MP_TIMER)		+= timer-mp-csky.o
 obj-$(CONFIG_GX6605S_TIMER)		+= timer-gx6605s.o
+obj-$(CONFIG_HYPERV_TIMER)		+= hyperv_timer.o
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
new file mode 100644
index 000000000000..68a28af31561
--- /dev/null
+++ b/drivers/clocksource/hyperv_timer.c
@@ -0,0 +1,200 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Clocksource driver for the synthetic counter and timers
+ * provided by the Hyper-V hypervisor to guest VMs, as described
+ * in the Hyper-V Top Level Functional Spec (TLFS). This driver
+ * is instruction set architecture independent.
+ *
+ * Copyright (C) 2019, Microsoft, Inc.
+ *
+ * Author:  Michael Kelley <mikelley@microsoft.com>
+ */
+
+#include <linux/percpu.h>
+#include <linux/cpumask.h>
+#include <linux/clockchips.h>
+#include <linux/mm.h>
+#include <clocksource/hyperv_timer.h>
+#include <asm/hyperv-tlfs.h>
+#include <asm/mshyperv.h>
+
+static struct clock_event_device __percpu *hv_clock_event;
+
+/*
+ * If false, we're using the old mechanism for stimer0 interrupts
+ * where it sends a VMbus message when it expires. The old
+ * mechanism is used when running on older versions of Hyper-V
+ * that don't support Direct Mode. While Hyper-V provides
+ * four stimer's per CPU, Linux uses only stimer0.
+ */
+static bool direct_mode_enabled;
+
+static int stimer0_irq;
+static int stimer0_vector;
+static int stimer0_message_sint;
+
+/*
+ * ISR for when stimer0 is operating in Direct Mode.  Direct Mode
+ * does not use VMbus or any VMbus messages, so process here and not
+ * in the VMbus driver code.
+ */
+void hv_stimer0_isr(void)
+{
+	struct clock_event_device *ce;
+
+	ce = this_cpu_ptr(hv_clock_event);
+	ce->event_handler(ce);
+}
+EXPORT_SYMBOL_GPL(hv_stimer0_isr);
+
+static int hv_ce_set_next_event(unsigned long delta,
+				struct clock_event_device *evt)
+{
+	u64 current_tick;
+
+	current_tick = hyperv_cs->read(NULL);
+	current_tick += delta;
+	hv_init_timer(0, current_tick);
+	return 0;
+}
+
+static int hv_ce_shutdown(struct clock_event_device *evt)
+{
+	hv_init_timer(0, 0);
+	hv_init_timer_config(0, 0);
+	if (direct_mode_enabled)
+		hv_disable_stimer0_percpu_irq(stimer0_irq);
+
+	return 0;
+}
+
+static int hv_ce_set_oneshot(struct clock_event_device *evt)
+{
+	union hv_stimer_config timer_cfg;
+
+	timer_cfg.as_uint64 = 0;
+	timer_cfg.enable = 1;
+	timer_cfg.auto_enable = 1;
+	if (direct_mode_enabled) {
+		/*
+		 * When it expires, the timer will directly interrupt
+		 * on the specified hardware vector/IRQ.
+		 */
+		timer_cfg.direct_mode = 1;
+		timer_cfg.apic_vector = stimer0_vector;
+		hv_enable_stimer0_percpu_irq(stimer0_irq);
+	} else {
+		/*
+		 * When it expires, the timer will generate a VMbus message,
+		 * to be handled by the normal VMbus interrupt handler.
+		 */
+		timer_cfg.direct_mode = 0;
+		timer_cfg.sintx = stimer0_message_sint;
+	}
+	hv_init_timer_config(0, timer_cfg.as_uint64);
+	return 0;
+}
+
+/*
+ * hv_stimer_init - Per-cpu initialization of the clockevent
+ */
+void hv_stimer_init(unsigned int cpu)
+{
+	struct clock_event_device *ce;
+
+	/*
+	 * Synthetic timers are always available except on old versions of
+	 * Hyper-V on x86.  In that case, just return as Linux will use a
+	 * clocksource based on emulated PIT or LAPIC timer hardware.
+	 */
+	if (!(ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE))
+		return;
+
+	ce = per_cpu_ptr(hv_clock_event, cpu);
+	ce->name = "Hyper-V clockevent";
+	ce->features = CLOCK_EVT_FEAT_ONESHOT;
+	ce->cpumask = cpumask_of(cpu);
+	ce->rating = 1000;
+	ce->set_state_shutdown = hv_ce_shutdown;
+	ce->set_state_oneshot = hv_ce_set_oneshot;
+	ce->set_next_event = hv_ce_set_next_event;
+
+	clockevents_config_and_register(ce,
+					HV_CLOCK_HZ,
+					HV_MIN_DELTA_TICKS,
+					HV_MAX_MAX_DELTA_TICKS);
+}
+EXPORT_SYMBOL_GPL(hv_stimer_init);
+
+/*
+ * hv_stimer_cleanup - Per-cpu cleanup of the clockevent
+ */
+void hv_stimer_cleanup(unsigned int cpu)
+{
+	struct clock_event_device *ce;
+
+	/* Turn off clockevent device */
+	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
+		ce = per_cpu_ptr(hv_clock_event, cpu);
+		hv_ce_shutdown(ce);
+	}
+}
+EXPORT_SYMBOL_GPL(hv_stimer_cleanup);
+
+/* hv_stimer_alloc - Global initialization of the clockevent and stimer0 */
+int hv_stimer_alloc(int sint)
+{
+	int ret;
+
+	hv_clock_event = alloc_percpu(struct clock_event_device);
+	if (!hv_clock_event)
+		return -ENOMEM;
+
+	direct_mode_enabled = ms_hyperv.misc_features &
+			HV_STIMER_DIRECT_MODE_AVAILABLE;
+	if (direct_mode_enabled) {
+		ret = hv_setup_stimer0_irq(&stimer0_irq, &stimer0_vector,
+				hv_stimer0_isr);
+		if (ret) {
+			free_percpu(hv_clock_event);
+			hv_clock_event = NULL;
+			return ret;
+		}
+	}
+
+	stimer0_message_sint = sint;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hv_stimer_alloc);
+
+/* hv_stimer_free - Free global resources allocated by hv_stimer_alloc() */
+void hv_stimer_free(void)
+{
+	if (direct_mode_enabled && (stimer0_irq != 0)) {
+		hv_remove_stimer0_irq(stimer0_irq);
+		stimer0_irq = 0;
+	}
+	free_percpu(hv_clock_event);
+	hv_clock_event = NULL;
+}
+EXPORT_SYMBOL_GPL(hv_stimer_free);
+
+/*
+ * Do a global cleanup of clockevents for the cases of kexec and
+ * vmbus exit
+ */
+void hv_stimer_global_cleanup(void)
+{
+	int	cpu;
+	struct clock_event_device *ce;
+
+	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
+		for_each_present_cpu(cpu) {
+			ce = per_cpu_ptr(hv_clock_event, cpu);
+			clockevents_unbind_device(ce, cpu);
+		}
+	}
+	hv_stimer_free();
+}
+EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 1c1a2514d6f3..c423e57ae888 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -10,6 +10,9 @@ config HYPERV
 	  Select this option to run Linux as a Hyper-V client operating
 	  system.
 
+config HYPERV_TIMER
+	def_bool HYPERV
+
 config HYPERV_TSCPAGE
        def_bool HYPERV && X86_64
 
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index a1ea482183e8..6188fb7dda42 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -16,27 +16,13 @@
 #include <linux/version.h>
 #include <linux/random.h>
 #include <linux/clockchips.h>
+#include <clocksource/hyperv_timer.h>
 #include <asm/mshyperv.h>
 #include "hyperv_vmbus.h"
 
 /* The one and only */
 struct hv_context hv_context;
 
-/*
- * If false, we're using the old mechanism for stimer0 interrupts
- * where it sends a VMbus message when it expires. The old
- * mechanism is used when running on older versions of Hyper-V
- * that don't support Direct Mode. While Hyper-V provides
- * four stimer's per CPU, Linux uses only stimer0.
- */
-static bool direct_mode_enabled;
-static int stimer0_irq;
-static int stimer0_vector;
-
-#define HV_TIMER_FREQUENCY (10 * 1000 * 1000) /* 100ns period */
-#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
-#define HV_MIN_DELTA_TICKS 1
-
 /*
  * hv_init - Main initialization routine.
  *
@@ -47,9 +33,6 @@ int hv_init(void)
 	hv_context.cpu_context = alloc_percpu(struct hv_per_cpu_context);
 	if (!hv_context.cpu_context)
 		return -ENOMEM;
-
-	direct_mode_enabled = ms_hyperv.misc_features &
-			HV_STIMER_DIRECT_MODE_AVAILABLE;
 	return 0;
 }
 
@@ -88,89 +71,6 @@ int hv_post_message(union hv_connection_id connection_id,
 	return status & 0xFFFF;
 }
 
-/*
- * ISR for when stimer0 is operating in Direct Mode.  Direct Mode
- * does not use VMbus or any VMbus messages, so process here and not
- * in the VMbus driver code.
- */
-
-static void hv_stimer0_isr(void)
-{
-	struct hv_per_cpu_context *hv_cpu;
-
-	hv_cpu = this_cpu_ptr(hv_context.cpu_context);
-	hv_cpu->clk_evt->event_handler(hv_cpu->clk_evt);
-	add_interrupt_randomness(stimer0_vector, 0);
-}
-
-static int hv_ce_set_next_event(unsigned long delta,
-				struct clock_event_device *evt)
-{
-	u64 current_tick;
-
-	WARN_ON(!clockevent_state_oneshot(evt));
-
-	current_tick = hyperv_cs->read(NULL);
-	current_tick += delta;
-	hv_init_timer(0, current_tick);
-	return 0;
-}
-
-static int hv_ce_shutdown(struct clock_event_device *evt)
-{
-	hv_init_timer(0, 0);
-	hv_init_timer_config(0, 0);
-	if (direct_mode_enabled)
-		hv_disable_stimer0_percpu_irq(stimer0_irq);
-
-	return 0;
-}
-
-static int hv_ce_set_oneshot(struct clock_event_device *evt)
-{
-	union hv_stimer_config timer_cfg;
-
-	timer_cfg.as_uint64 = 0;
-	timer_cfg.enable = 1;
-	timer_cfg.auto_enable = 1;
-	if (direct_mode_enabled) {
-		/*
-		 * When it expires, the timer will directly interrupt
-		 * on the specified hardware vector/IRQ.
-		 */
-		timer_cfg.direct_mode = 1;
-		timer_cfg.apic_vector = stimer0_vector;
-		hv_enable_stimer0_percpu_irq(stimer0_irq);
-	} else {
-		/*
-		 * When it expires, the timer will generate a VMbus message,
-		 * to be handled by the normal VMbus interrupt handler.
-		 */
-		timer_cfg.direct_mode = 0;
-		timer_cfg.sintx = VMBUS_MESSAGE_SINT;
-	}
-	hv_init_timer_config(0, timer_cfg.as_uint64);
-	return 0;
-}
-
-static void hv_init_clockevent_device(struct clock_event_device *dev, int cpu)
-{
-	dev->name = "Hyper-V clockevent";
-	dev->features = CLOCK_EVT_FEAT_ONESHOT;
-	dev->cpumask = cpumask_of(cpu);
-	dev->rating = 1000;
-	/*
-	 * Avoid settint dev->owner = THIS_MODULE deliberately as doing so will
-	 * result in clockevents_config_and_register() taking additional
-	 * references to the hv_vmbus module making it impossible to unload.
-	 */
-
-	dev->set_state_shutdown = hv_ce_shutdown;
-	dev->set_state_oneshot = hv_ce_set_oneshot;
-	dev->set_next_event = hv_ce_set_next_event;
-}
-
-
 int hv_synic_alloc(void)
 {
 	int cpu;
@@ -199,14 +99,6 @@ int hv_synic_alloc(void)
 		tasklet_init(&hv_cpu->msg_dpc,
 			     vmbus_on_msg_dpc, (unsigned long) hv_cpu);
 
-		hv_cpu->clk_evt = kzalloc(sizeof(struct clock_event_device),
-					  GFP_KERNEL);
-		if (hv_cpu->clk_evt == NULL) {
-			pr_err("Unable to allocate clock event device\n");
-			goto err;
-		}
-		hv_init_clockevent_device(hv_cpu->clk_evt, cpu);
-
 		hv_cpu->synic_message_page =
 			(void *)get_zeroed_page(GFP_ATOMIC);
 		if (hv_cpu->synic_message_page == NULL) {
@@ -229,11 +121,6 @@ int hv_synic_alloc(void)
 		INIT_LIST_HEAD(&hv_cpu->chan_list);
 	}
 
-	if (direct_mode_enabled &&
-	    hv_setup_stimer0_irq(&stimer0_irq, &stimer0_vector,
-				hv_stimer0_isr))
-		goto err;
-
 	return 0;
 err:
 	/*
@@ -252,7 +139,6 @@ void hv_synic_free(void)
 		struct hv_per_cpu_context *hv_cpu
 			= per_cpu_ptr(hv_context.cpu_context, cpu);
 
-		kfree(hv_cpu->clk_evt);
 		free_page((unsigned long)hv_cpu->synic_event_page);
 		free_page((unsigned long)hv_cpu->synic_message_page);
 		free_page((unsigned long)hv_cpu->post_msg_page);
@@ -311,36 +197,9 @@ int hv_synic_init(unsigned int cpu)
 
 	hv_set_synic_state(sctrl.as_uint64);
 
-	/*
-	 * Register the per-cpu clockevent source.
-	 */
-	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE)
-		clockevents_config_and_register(hv_cpu->clk_evt,
-						HV_TIMER_FREQUENCY,
-						HV_MIN_DELTA_TICKS,
-						HV_MAX_MAX_DELTA_TICKS);
-	return 0;
-}
-
-/*
- * hv_synic_clockevents_cleanup - Cleanup clockevent devices
- */
-void hv_synic_clockevents_cleanup(void)
-{
-	int cpu;
+	hv_stimer_init(cpu);
 
-	if (!(ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE))
-		return;
-
-	if (direct_mode_enabled)
-		hv_remove_stimer0_irq(stimer0_irq);
-
-	for_each_present_cpu(cpu) {
-		struct hv_per_cpu_context *hv_cpu
-			= per_cpu_ptr(hv_context.cpu_context, cpu);
-
-		clockevents_unbind_device(hv_cpu->clk_evt, cpu);
-	}
+	return 0;
 }
 
 /*
@@ -388,14 +247,7 @@ int hv_synic_cleanup(unsigned int cpu)
 	if (channel_found && vmbus_connection.conn_state == CONNECTED)
 		return -EBUSY;
 
-	/* Turn off clockevent device */
-	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
-		struct hv_per_cpu_context *hv_cpu
-			= this_cpu_ptr(hv_context.cpu_context);
-
-		clockevents_unbind_device(hv_cpu->clk_evt, cpu);
-		hv_ce_shutdown(hv_cpu->clk_evt);
-	}
+	hv_stimer_cleanup(cpu);
 
 	hv_get_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index b8e1ff05f110..362e70e9d145 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -138,7 +138,6 @@ struct hv_per_cpu_context {
 	 * per-cpu list of the channels based on their CPU affinity.
 	 */
 	struct list_head chan_list;
-	struct clock_event_device *clk_evt;
 };
 
 struct hv_context {
@@ -176,8 +175,6 @@ extern int hv_synic_init(unsigned int cpu);
 
 extern int hv_synic_cleanup(unsigned int cpu);
 
-extern void hv_synic_clockevents_cleanup(void);
-
 /* Interface */
 
 void hv_ringbuffer_pre_init(struct vmbus_channel *channel);
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 92b1874b3eb3..72d5a7cde7ea 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -30,6 +30,7 @@
 #include <linux/kdebug.h>
 #include <linux/efi.h>
 #include <linux/random.h>
+#include <clocksource/hyperv_timer.h>
 #include "hyperv_vmbus.h"
 
 struct vmbus_dynid {
@@ -955,17 +956,6 @@ static void vmbus_onmessage_work(struct work_struct *work)
 	kfree(ctx);
 }
 
-static void hv_process_timer_expiration(struct hv_message *msg,
-					struct hv_per_cpu_context *hv_cpu)
-{
-	struct clock_event_device *dev = hv_cpu->clk_evt;
-
-	if (dev->event_handler)
-		dev->event_handler(dev);
-
-	vmbus_signal_eom(msg, HVMSG_TIMER_EXPIRED);
-}
-
 void vmbus_on_msg_dpc(unsigned long data)
 {
 	struct hv_per_cpu_context *hv_cpu = (void *)data;
@@ -1159,9 +1149,10 @@ static void vmbus_isr(void)
 
 	/* Check if there are actual msgs to be processed */
 	if (msg->header.message_type != HVMSG_NONE) {
-		if (msg->header.message_type == HVMSG_TIMER_EXPIRED)
-			hv_process_timer_expiration(msg, hv_cpu);
-		else
+		if (msg->header.message_type == HVMSG_TIMER_EXPIRED) {
+			hv_stimer0_isr();
+			vmbus_signal_eom(msg, HVMSG_TIMER_EXPIRED);
+		} else
 			tasklet_schedule(&hv_cpu->msg_dpc);
 	}
 
@@ -1263,14 +1254,19 @@ static int vmbus_bus_init(void)
 	ret = hv_synic_alloc();
 	if (ret)
 		goto err_alloc;
+
+	ret = hv_stimer_alloc(VMBUS_MESSAGE_SINT);
+	if (ret < 0)
+		goto err_alloc;
+
 	/*
-	 * Initialize the per-cpu interrupt state and
-	 * connect to the host.
+	 * Initialize the per-cpu interrupt state and stimer state.
+	 * Then connect to the host.
 	 */
 	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hyperv/vmbus:online",
 				hv_synic_init, hv_synic_cleanup);
 	if (ret < 0)
-		goto err_alloc;
+		goto err_cpuhp;
 	hyperv_cpuhp_online = ret;
 
 	ret = vmbus_connect();
@@ -1318,6 +1314,8 @@ static int vmbus_bus_init(void)
 
 err_connect:
 	cpuhp_remove_state(hyperv_cpuhp_online);
+err_cpuhp:
+	hv_stimer_free();
 err_alloc:
 	hv_synic_free();
 	hv_remove_vmbus_irq();
@@ -2064,7 +2062,7 @@ static struct acpi_driver vmbus_acpi_driver = {
 
 static void hv_kexec_handler(void)
 {
-	hv_synic_clockevents_cleanup();
+	hv_stimer_global_cleanup();
 	vmbus_initiate_unload(false);
 	vmbus_connection.conn_state = DISCONNECTED;
 	/* Make sure conn_state is set as hv_synic_cleanup checks for it */
@@ -2075,6 +2073,8 @@ static void hv_kexec_handler(void)
 
 static void hv_crash_handler(struct pt_regs *regs)
 {
+	int cpu;
+
 	vmbus_initiate_unload(true);
 	/*
 	 * In crash handler we can't schedule synic cleanup for all CPUs,
@@ -2082,7 +2082,9 @@ static void hv_crash_handler(struct pt_regs *regs)
 	 * for kdump.
 	 */
 	vmbus_connection.conn_state = DISCONNECTED;
-	hv_synic_cleanup(smp_processor_id());
+	cpu = smp_processor_id();
+	hv_stimer_cleanup(cpu);
+	hv_synic_cleanup(cpu);
 	hyperv_cleanup();
 };
 
@@ -2131,7 +2133,7 @@ static void __exit vmbus_exit(void)
 	hv_remove_kexec_handler();
 	hv_remove_crash_handler();
 	vmbus_connection.conn_state = DISCONNECTED;
-	hv_synic_clockevents_cleanup();
+	hv_stimer_global_cleanup();
 	vmbus_disconnect();
 	hv_remove_vmbus_irq();
 	for_each_online_cpu(cpu) {
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
new file mode 100644
index 000000000000..0cd73f7bc992
--- /dev/null
+++ b/include/clocksource/hyperv_timer.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Definitions for the clocksource provided by the Hyper-V
+ * hypervisor to guest VMs, as described in the Hyper-V Top
+ * Level Functional Spec (TLFS).
+ *
+ * Copyright (C) 2019, Microsoft, Inc.
+ *
+ * Author:  Michael Kelley <mikelley@microsoft.com>
+ */
+
+#ifndef __CLKSOURCE_HYPERV_TIMER_H
+#define __CLKSOURCE_HYPERV_TIMER_H
+
+#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
+#define HV_MIN_DELTA_TICKS 1
+
+/* Routines called by the VMbus driver */
+extern int hv_stimer_alloc(int sint);
+extern void hv_stimer_free(void);
+extern void hv_stimer_init(unsigned int cpu);
+extern void hv_stimer_cleanup(unsigned int cpu);
+extern void hv_stimer_global_cleanup(void);
+extern void hv_stimer0_isr(void);
+
+#endif

[tip:timers/core] clocksource/drivers: Make Hyper-V clocksource ISA agnostic

[tip-bot for Michael Kelley]

Commit-ID:  fd1fea6834d0f9f93062ae6685862908a9baed39
Gitweb:     https://git.kernel.org/tip/fd1fea6834d0f9f93062ae6685862908a9baed39
Author:     Michael Kelley <mikelley@microsoft.com>
AuthorDate: Mon, 1 Jul 2019 04:25:56 +0000
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 3 Jul 2019 11:00:59 +0200

clocksource/drivers: Make Hyper-V clocksource ISA agnostic

Hyper-V clock/timer code and data structures are currently mixed
in with other code in the ISA independent drivers/hv directory as
well as the ISA dependent Hyper-V code under arch/x86.

Consolidate this code and data structures into a Hyper-V clocksource driver
to better follow the Linux model. In doing so, separate out the ISA
dependent portions so the new clocksource driver works for x86 and for the
in-process Hyper-V on ARM64 code.

To start, move the existing clockevents code to create the new clocksource
driver. Update the VMbus driver to call initialization and cleanup routines
since the Hyper-V synthetic timers are not independently enumerated in
ACPI.

No behavior is changed and no new functionality is added.

Suggested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: "bp@alien8.de" <bp@alien8.de>
Cc: "will.deacon@arm.com" <will.deacon@arm.com>
Cc: "catalin.marinas@arm.com" <catalin.marinas@arm.com>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>
Cc: "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Cc: "olaf@aepfle.de" <olaf@aepfle.de>
Cc: "apw@canonical.com" <apw@canonical.com>
Cc: "jasowang@redhat.com" <jasowang@redhat.com>
Cc: "marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>
Cc: Sunil Muthuswamy <sunilmut@microsoft.com>
Cc: KY Srinivasan <kys@microsoft.com>
Cc: "sashal@kernel.org" <sashal@kernel.org>
Cc: "vincenzo.frascino@arm.com" <vincenzo.frascino@arm.com>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Cc: "linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>
Cc: "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>
Cc: "arnd@arndb.de" <arnd@arndb.de>
Cc: "linux@armlinux.org.uk" <linux@armlinux.org.uk>
Cc: "ralf@linux-mips.org" <ralf@linux-mips.org>
Cc: "paul.burton@mips.com" <paul.burton@mips.com>
Cc: "daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>
Cc: "salyzyn@android.com" <salyzyn@android.com>
Cc: "pcc@google.com" <pcc@google.com>
Cc: "shuah@kernel.org" <shuah@kernel.org>
Cc: "0x7f454c46@gmail.com" <0x7f454c46@gmail.com>
Cc: "linux@rasmusvillemoes.dk" <linux@rasmusvillemoes.dk>
Cc: "huw@codeweavers.com" <huw@codeweavers.com>
Cc: "sfr@canb.auug.org.au" <sfr@canb.auug.org.au>
Cc: "pbonzini@redhat.com" <pbonzini@redhat.com>
Cc: "rkrcmar@redhat.com" <rkrcmar@redhat.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Link: https://lkml.kernel.org/r/1561955054-1838-2-git-send-email-mikelley@microsoft.com

---
 MAINTAINERS                        |   2 +
 arch/x86/include/asm/hyperv-tlfs.h |   6 ++
 arch/x86/kernel/cpu/mshyperv.c     |   4 +-
 drivers/clocksource/Makefile       |   1 +
 drivers/clocksource/hyperv_timer.c | 200 +++++++++++++++++++++++++++++++++++++
 drivers/hv/Kconfig                 |   3 +
 drivers/hv/hv.c                    | 156 +----------------------------
 drivers/hv/hyperv_vmbus.h          |   3 -
 drivers/hv/vmbus_drv.c             |  42 ++++----
 include/clocksource/hyperv_timer.h |  27 +++++
 10 files changed, 268 insertions(+), 176 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index a2812972b7b0..bfde42a76a95 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7313,6 +7313,7 @@ F:	arch/x86/include/asm/trace/hyperv.h
 F:	arch/x86/include/asm/hyperv-tlfs.h
 F:	arch/x86/kernel/cpu/mshyperv.c
 F:	arch/x86/hyperv
+F:	drivers/clocksource/hyperv_timer.c
 F:	drivers/hid/hid-hyperv.c
 F:	drivers/hv/
 F:	drivers/input/serio/hyperv-keyboard.c
@@ -7323,6 +7324,7 @@ F:	drivers/uio/uio_hv_generic.c
 F:	drivers/video/fbdev/hyperv_fb.c
 F:	drivers/iommu/hyperv_iommu.c
 F:	net/vmw_vsock/hyperv_transport.c
+F:	include/clocksource/hyperv_timer.h
 F:	include/linux/hyperv.h
 F:	include/uapi/linux/hyperv.h
 F:	tools/hv/
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index cdf44aa9a501..af78cd72b8f3 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -401,6 +401,12 @@ enum HV_GENERIC_SET_FORMAT {
 #define HV_STATUS_INVALID_CONNECTION_ID		18
 #define HV_STATUS_INSUFFICIENT_BUFFERS		19
 
+/*
+ * The Hyper-V TimeRefCount register and the TSC
+ * page provide a guest VM clock with 100ns tick rate
+ */
+#define HV_CLOCK_HZ (NSEC_PER_SEC/100)
+
 typedef struct _HV_REFERENCE_TSC_PAGE {
 	__u32 tsc_sequence;
 	__u32 res1;
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 7df29f08871b..1e5f7a03ddf5 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -17,6 +17,7 @@
 #include <linux/irq.h>
 #include <linux/kexec.h>
 #include <linux/i8253.h>
+#include <linux/random.h>
 #include <asm/processor.h>
 #include <asm/hypervisor.h>
 #include <asm/hyperv-tlfs.h>
@@ -80,6 +81,7 @@ __visible void __irq_entry hv_stimer0_vector_handler(struct pt_regs *regs)
 	inc_irq_stat(hyperv_stimer0_count);
 	if (hv_stimer0_handler)
 		hv_stimer0_handler();
+	add_interrupt_randomness(HYPERV_STIMER0_VECTOR, 0);
 	ack_APIC_irq();
 
 	exiting_irq();
@@ -89,7 +91,7 @@ __visible void __irq_entry hv_stimer0_vector_handler(struct pt_regs *regs)
 int hv_setup_stimer0_irq(int *irq, int *vector, void (*handler)(void))
 {
 	*vector = HYPERV_STIMER0_VECTOR;
-	*irq = 0;   /* Unused on x86/x64 */
+	*irq = -1;   /* Unused on x86/x64 */
 	hv_stimer0_handler = handler;
 	return 0;
 }
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 5582252efb31..2e7936e7833f 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -86,3 +86,4 @@ obj-$(CONFIG_ATCPIT100_TIMER)		+= timer-atcpit100.o
 obj-$(CONFIG_RISCV_TIMER)		+= timer-riscv.o
 obj-$(CONFIG_CSKY_MP_TIMER)		+= timer-mp-csky.o
 obj-$(CONFIG_GX6605S_TIMER)		+= timer-gx6605s.o
+obj-$(CONFIG_HYPERV_TIMER)		+= hyperv_timer.o
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
new file mode 100644
index 000000000000..68a28af31561
--- /dev/null
+++ b/drivers/clocksource/hyperv_timer.c
@@ -0,0 +1,200 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Clocksource driver for the synthetic counter and timers
+ * provided by the Hyper-V hypervisor to guest VMs, as described
+ * in the Hyper-V Top Level Functional Spec (TLFS). This driver
+ * is instruction set architecture independent.
+ *
+ * Copyright (C) 2019, Microsoft, Inc.
+ *
+ * Author:  Michael Kelley <mikelley@microsoft.com>
+ */
+
+#include <linux/percpu.h>
+#include <linux/cpumask.h>
+#include <linux/clockchips.h>
+#include <linux/mm.h>
+#include <clocksource/hyperv_timer.h>
+#include <asm/hyperv-tlfs.h>
+#include <asm/mshyperv.h>
+
+static struct clock_event_device __percpu *hv_clock_event;
+
+/*
+ * If false, we're using the old mechanism for stimer0 interrupts
+ * where it sends a VMbus message when it expires. The old
+ * mechanism is used when running on older versions of Hyper-V
+ * that don't support Direct Mode. While Hyper-V provides
+ * four stimer's per CPU, Linux uses only stimer0.
+ */
+static bool direct_mode_enabled;
+
+static int stimer0_irq;
+static int stimer0_vector;
+static int stimer0_message_sint;
+
+/*
+ * ISR for when stimer0 is operating in Direct Mode.  Direct Mode
+ * does not use VMbus or any VMbus messages, so process here and not
+ * in the VMbus driver code.
+ */
+void hv_stimer0_isr(void)
+{
+	struct clock_event_device *ce;
+
+	ce = this_cpu_ptr(hv_clock_event);
+	ce->event_handler(ce);
+}
+EXPORT_SYMBOL_GPL(hv_stimer0_isr);
+
+static int hv_ce_set_next_event(unsigned long delta,
+				struct clock_event_device *evt)
+{
+	u64 current_tick;
+
+	current_tick = hyperv_cs->read(NULL);
+	current_tick += delta;
+	hv_init_timer(0, current_tick);
+	return 0;
+}
+
+static int hv_ce_shutdown(struct clock_event_device *evt)
+{
+	hv_init_timer(0, 0);
+	hv_init_timer_config(0, 0);
+	if (direct_mode_enabled)
+		hv_disable_stimer0_percpu_irq(stimer0_irq);
+
+	return 0;
+}
+
+static int hv_ce_set_oneshot(struct clock_event_device *evt)
+{
+	union hv_stimer_config timer_cfg;
+
+	timer_cfg.as_uint64 = 0;
+	timer_cfg.enable = 1;
+	timer_cfg.auto_enable = 1;
+	if (direct_mode_enabled) {
+		/*
+		 * When it expires, the timer will directly interrupt
+		 * on the specified hardware vector/IRQ.
+		 */
+		timer_cfg.direct_mode = 1;
+		timer_cfg.apic_vector = stimer0_vector;
+		hv_enable_stimer0_percpu_irq(stimer0_irq);
+	} else {
+		/*
+		 * When it expires, the timer will generate a VMbus message,
+		 * to be handled by the normal VMbus interrupt handler.
+		 */
+		timer_cfg.direct_mode = 0;
+		timer_cfg.sintx = stimer0_message_sint;
+	}
+	hv_init_timer_config(0, timer_cfg.as_uint64);
+	return 0;
+}
+
+/*
+ * hv_stimer_init - Per-cpu initialization of the clockevent
+ */
+void hv_stimer_init(unsigned int cpu)
+{
+	struct clock_event_device *ce;
+
+	/*
+	 * Synthetic timers are always available except on old versions of
+	 * Hyper-V on x86.  In that case, just return as Linux will use a
+	 * clocksource based on emulated PIT or LAPIC timer hardware.
+	 */
+	if (!(ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE))
+		return;
+
+	ce = per_cpu_ptr(hv_clock_event, cpu);
+	ce->name = "Hyper-V clockevent";
+	ce->features = CLOCK_EVT_FEAT_ONESHOT;
+	ce->cpumask = cpumask_of(cpu);
+	ce->rating = 1000;
+	ce->set_state_shutdown = hv_ce_shutdown;
+	ce->set_state_oneshot = hv_ce_set_oneshot;
+	ce->set_next_event = hv_ce_set_next_event;
+
+	clockevents_config_and_register(ce,
+					HV_CLOCK_HZ,
+					HV_MIN_DELTA_TICKS,
+					HV_MAX_MAX_DELTA_TICKS);
+}
+EXPORT_SYMBOL_GPL(hv_stimer_init);
+
+/*
+ * hv_stimer_cleanup - Per-cpu cleanup of the clockevent
+ */
+void hv_stimer_cleanup(unsigned int cpu)
+{
+	struct clock_event_device *ce;
+
+	/* Turn off clockevent device */
+	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
+		ce = per_cpu_ptr(hv_clock_event, cpu);
+		hv_ce_shutdown(ce);
+	}
+}
+EXPORT_SYMBOL_GPL(hv_stimer_cleanup);
+
+/* hv_stimer_alloc - Global initialization of the clockevent and stimer0 */
+int hv_stimer_alloc(int sint)
+{
+	int ret;
+
+	hv_clock_event = alloc_percpu(struct clock_event_device);
+	if (!hv_clock_event)
+		return -ENOMEM;
+
+	direct_mode_enabled = ms_hyperv.misc_features &
+			HV_STIMER_DIRECT_MODE_AVAILABLE;
+	if (direct_mode_enabled) {
+		ret = hv_setup_stimer0_irq(&stimer0_irq, &stimer0_vector,
+				hv_stimer0_isr);
+		if (ret) {
+			free_percpu(hv_clock_event);
+			hv_clock_event = NULL;
+			return ret;
+		}
+	}
+
+	stimer0_message_sint = sint;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hv_stimer_alloc);
+
+/* hv_stimer_free - Free global resources allocated by hv_stimer_alloc() */
+void hv_stimer_free(void)
+{
+	if (direct_mode_enabled && (stimer0_irq != 0)) {
+		hv_remove_stimer0_irq(stimer0_irq);
+		stimer0_irq = 0;
+	}
+	free_percpu(hv_clock_event);
+	hv_clock_event = NULL;
+}
+EXPORT_SYMBOL_GPL(hv_stimer_free);
+
+/*
+ * Do a global cleanup of clockevents for the cases of kexec and
+ * vmbus exit
+ */
+void hv_stimer_global_cleanup(void)
+{
+	int	cpu;
+	struct clock_event_device *ce;
+
+	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
+		for_each_present_cpu(cpu) {
+			ce = per_cpu_ptr(hv_clock_event, cpu);
+			clockevents_unbind_device(ce, cpu);
+		}
+	}
+	hv_stimer_free();
+}
+EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 1c1a2514d6f3..c423e57ae888 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -10,6 +10,9 @@ config HYPERV
 	  Select this option to run Linux as a Hyper-V client operating
 	  system.
 
+config HYPERV_TIMER
+	def_bool HYPERV
+
 config HYPERV_TSCPAGE
        def_bool HYPERV && X86_64
 
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index a1ea482183e8..6188fb7dda42 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -16,27 +16,13 @@
 #include <linux/version.h>
 #include <linux/random.h>
 #include <linux/clockchips.h>
+#include <clocksource/hyperv_timer.h>
 #include <asm/mshyperv.h>
 #include "hyperv_vmbus.h"
 
 /* The one and only */
 struct hv_context hv_context;
 
-/*
- * If false, we're using the old mechanism for stimer0 interrupts
- * where it sends a VMbus message when it expires. The old
- * mechanism is used when running on older versions of Hyper-V
- * that don't support Direct Mode. While Hyper-V provides
- * four stimer's per CPU, Linux uses only stimer0.
- */
-static bool direct_mode_enabled;
-static int stimer0_irq;
-static int stimer0_vector;
-
-#define HV_TIMER_FREQUENCY (10 * 1000 * 1000) /* 100ns period */
-#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
-#define HV_MIN_DELTA_TICKS 1
-
 /*
  * hv_init - Main initialization routine.
  *
@@ -47,9 +33,6 @@ int hv_init(void)
 	hv_context.cpu_context = alloc_percpu(struct hv_per_cpu_context);
 	if (!hv_context.cpu_context)
 		return -ENOMEM;
-
-	direct_mode_enabled = ms_hyperv.misc_features &
-			HV_STIMER_DIRECT_MODE_AVAILABLE;
 	return 0;
 }
 
@@ -88,89 +71,6 @@ int hv_post_message(union hv_connection_id connection_id,
 	return status & 0xFFFF;
 }
 
-/*
- * ISR for when stimer0 is operating in Direct Mode.  Direct Mode
- * does not use VMbus or any VMbus messages, so process here and not
- * in the VMbus driver code.
- */
-
-static void hv_stimer0_isr(void)
-{
-	struct hv_per_cpu_context *hv_cpu;
-
-	hv_cpu = this_cpu_ptr(hv_context.cpu_context);
-	hv_cpu->clk_evt->event_handler(hv_cpu->clk_evt);
-	add_interrupt_randomness(stimer0_vector, 0);
-}
-
-static int hv_ce_set_next_event(unsigned long delta,
-				struct clock_event_device *evt)
-{
-	u64 current_tick;
-
-	WARN_ON(!clockevent_state_oneshot(evt));
-
-	current_tick = hyperv_cs->read(NULL);
-	current_tick += delta;
-	hv_init_timer(0, current_tick);
-	return 0;
-}
-
-static int hv_ce_shutdown(struct clock_event_device *evt)
-{
-	hv_init_timer(0, 0);
-	hv_init_timer_config(0, 0);
-	if (direct_mode_enabled)
-		hv_disable_stimer0_percpu_irq(stimer0_irq);
-
-	return 0;
-}
-
-static int hv_ce_set_oneshot(struct clock_event_device *evt)
-{
-	union hv_stimer_config timer_cfg;
-
-	timer_cfg.as_uint64 = 0;
-	timer_cfg.enable = 1;
-	timer_cfg.auto_enable = 1;
-	if (direct_mode_enabled) {
-		/*
-		 * When it expires, the timer will directly interrupt
-		 * on the specified hardware vector/IRQ.
-		 */
-		timer_cfg.direct_mode = 1;
-		timer_cfg.apic_vector = stimer0_vector;
-		hv_enable_stimer0_percpu_irq(stimer0_irq);
-	} else {
-		/*
-		 * When it expires, the timer will generate a VMbus message,
-		 * to be handled by the normal VMbus interrupt handler.
-		 */
-		timer_cfg.direct_mode = 0;
-		timer_cfg.sintx = VMBUS_MESSAGE_SINT;
-	}
-	hv_init_timer_config(0, timer_cfg.as_uint64);
-	return 0;
-}
-
-static void hv_init_clockevent_device(struct clock_event_device *dev, int cpu)
-{
-	dev->name = "Hyper-V clockevent";
-	dev->features = CLOCK_EVT_FEAT_ONESHOT;
-	dev->cpumask = cpumask_of(cpu);
-	dev->rating = 1000;
-	/*
-	 * Avoid settint dev->owner = THIS_MODULE deliberately as doing so will
-	 * result in clockevents_config_and_register() taking additional
-	 * references to the hv_vmbus module making it impossible to unload.
-	 */
-
-	dev->set_state_shutdown = hv_ce_shutdown;
-	dev->set_state_oneshot = hv_ce_set_oneshot;
-	dev->set_next_event = hv_ce_set_next_event;
-}
-
-
 int hv_synic_alloc(void)
 {
 	int cpu;
@@ -199,14 +99,6 @@ int hv_synic_alloc(void)
 		tasklet_init(&hv_cpu->msg_dpc,
 			     vmbus_on_msg_dpc, (unsigned long) hv_cpu);
 
-		hv_cpu->clk_evt = kzalloc(sizeof(struct clock_event_device),
-					  GFP_KERNEL);
-		if (hv_cpu->clk_evt == NULL) {
-			pr_err("Unable to allocate clock event device\n");
-			goto err;
-		}
-		hv_init_clockevent_device(hv_cpu->clk_evt, cpu);
-
 		hv_cpu->synic_message_page =
 			(void *)get_zeroed_page(GFP_ATOMIC);
 		if (hv_cpu->synic_message_page == NULL) {
@@ -229,11 +121,6 @@ int hv_synic_alloc(void)
 		INIT_LIST_HEAD(&hv_cpu->chan_list);
 	}
 
-	if (direct_mode_enabled &&
-	    hv_setup_stimer0_irq(&stimer0_irq, &stimer0_vector,
-				hv_stimer0_isr))
-		goto err;
-
 	return 0;
 err:
 	/*
@@ -252,7 +139,6 @@ void hv_synic_free(void)
 		struct hv_per_cpu_context *hv_cpu
 			= per_cpu_ptr(hv_context.cpu_context, cpu);
 
-		kfree(hv_cpu->clk_evt);
 		free_page((unsigned long)hv_cpu->synic_event_page);
 		free_page((unsigned long)hv_cpu->synic_message_page);
 		free_page((unsigned long)hv_cpu->post_msg_page);
@@ -311,36 +197,9 @@ int hv_synic_init(unsigned int cpu)
 
 	hv_set_synic_state(sctrl.as_uint64);
 
-	/*
-	 * Register the per-cpu clockevent source.
-	 */
-	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE)
-		clockevents_config_and_register(hv_cpu->clk_evt,
-						HV_TIMER_FREQUENCY,
-						HV_MIN_DELTA_TICKS,
-						HV_MAX_MAX_DELTA_TICKS);
-	return 0;
-}
-
-/*
- * hv_synic_clockevents_cleanup - Cleanup clockevent devices
- */
-void hv_synic_clockevents_cleanup(void)
-{
-	int cpu;
+	hv_stimer_init(cpu);
 
-	if (!(ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE))
-		return;
-
-	if (direct_mode_enabled)
-		hv_remove_stimer0_irq(stimer0_irq);
-
-	for_each_present_cpu(cpu) {
-		struct hv_per_cpu_context *hv_cpu
-			= per_cpu_ptr(hv_context.cpu_context, cpu);
-
-		clockevents_unbind_device(hv_cpu->clk_evt, cpu);
-	}
+	return 0;
 }
 
 /*
@@ -388,14 +247,7 @@ int hv_synic_cleanup(unsigned int cpu)
 	if (channel_found && vmbus_connection.conn_state == CONNECTED)
 		return -EBUSY;
 
-	/* Turn off clockevent device */
-	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
-		struct hv_per_cpu_context *hv_cpu
-			= this_cpu_ptr(hv_context.cpu_context);
-
-		clockevents_unbind_device(hv_cpu->clk_evt, cpu);
-		hv_ce_shutdown(hv_cpu->clk_evt);
-	}
+	hv_stimer_cleanup(cpu);
 
 	hv_get_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
 
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index b8e1ff05f110..362e70e9d145 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -138,7 +138,6 @@ struct hv_per_cpu_context {
 	 * per-cpu list of the channels based on their CPU affinity.
 	 */
 	struct list_head chan_list;
-	struct clock_event_device *clk_evt;
 };
 
 struct hv_context {
@@ -176,8 +175,6 @@ extern int hv_synic_init(unsigned int cpu);
 
 extern int hv_synic_cleanup(unsigned int cpu);
 
-extern void hv_synic_clockevents_cleanup(void);
-
 /* Interface */
 
 void hv_ringbuffer_pre_init(struct vmbus_channel *channel);
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 92b1874b3eb3..72d5a7cde7ea 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -30,6 +30,7 @@
 #include <linux/kdebug.h>
 #include <linux/efi.h>
 #include <linux/random.h>
+#include <clocksource/hyperv_timer.h>
 #include "hyperv_vmbus.h"
 
 struct vmbus_dynid {
@@ -955,17 +956,6 @@ static void vmbus_onmessage_work(struct work_struct *work)
 	kfree(ctx);
 }
 
-static void hv_process_timer_expiration(struct hv_message *msg,
-					struct hv_per_cpu_context *hv_cpu)
-{
-	struct clock_event_device *dev = hv_cpu->clk_evt;
-
-	if (dev->event_handler)
-		dev->event_handler(dev);
-
-	vmbus_signal_eom(msg, HVMSG_TIMER_EXPIRED);
-}
-
 void vmbus_on_msg_dpc(unsigned long data)
 {
 	struct hv_per_cpu_context *hv_cpu = (void *)data;
@@ -1159,9 +1149,10 @@ static void vmbus_isr(void)
 
 	/* Check if there are actual msgs to be processed */
 	if (msg->header.message_type != HVMSG_NONE) {
-		if (msg->header.message_type == HVMSG_TIMER_EXPIRED)
-			hv_process_timer_expiration(msg, hv_cpu);
-		else
+		if (msg->header.message_type == HVMSG_TIMER_EXPIRED) {
+			hv_stimer0_isr();
+			vmbus_signal_eom(msg, HVMSG_TIMER_EXPIRED);
+		} else
 			tasklet_schedule(&hv_cpu->msg_dpc);
 	}
 
@@ -1263,14 +1254,19 @@ static int vmbus_bus_init(void)
 	ret = hv_synic_alloc();
 	if (ret)
 		goto err_alloc;
+
+	ret = hv_stimer_alloc(VMBUS_MESSAGE_SINT);
+	if (ret < 0)
+		goto err_alloc;
+
 	/*
-	 * Initialize the per-cpu interrupt state and
-	 * connect to the host.
+	 * Initialize the per-cpu interrupt state and stimer state.
+	 * Then connect to the host.
 	 */
 	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hyperv/vmbus:online",
 				hv_synic_init, hv_synic_cleanup);
 	if (ret < 0)
-		goto err_alloc;
+		goto err_cpuhp;
 	hyperv_cpuhp_online = ret;
 
 	ret = vmbus_connect();
@@ -1318,6 +1314,8 @@ static int vmbus_bus_init(void)
 
 err_connect:
 	cpuhp_remove_state(hyperv_cpuhp_online);
+err_cpuhp:
+	hv_stimer_free();
 err_alloc:
 	hv_synic_free();
 	hv_remove_vmbus_irq();
@@ -2064,7 +2062,7 @@ static struct acpi_driver vmbus_acpi_driver = {
 
 static void hv_kexec_handler(void)
 {
-	hv_synic_clockevents_cleanup();
+	hv_stimer_global_cleanup();
 	vmbus_initiate_unload(false);
 	vmbus_connection.conn_state = DISCONNECTED;
 	/* Make sure conn_state is set as hv_synic_cleanup checks for it */
@@ -2075,6 +2073,8 @@ static void hv_kexec_handler(void)
 
 static void hv_crash_handler(struct pt_regs *regs)
 {
+	int cpu;
+
 	vmbus_initiate_unload(true);
 	/*
 	 * In crash handler we can't schedule synic cleanup for all CPUs,
@@ -2082,7 +2082,9 @@ static void hv_crash_handler(struct pt_regs *regs)
 	 * for kdump.
 	 */
 	vmbus_connection.conn_state = DISCONNECTED;
-	hv_synic_cleanup(smp_processor_id());
+	cpu = smp_processor_id();
+	hv_stimer_cleanup(cpu);
+	hv_synic_cleanup(cpu);
 	hyperv_cleanup();
 };
 
@@ -2131,7 +2133,7 @@ static void __exit vmbus_exit(void)
 	hv_remove_kexec_handler();
 	hv_remove_crash_handler();
 	vmbus_connection.conn_state = DISCONNECTED;
-	hv_synic_clockevents_cleanup();
+	hv_stimer_global_cleanup();
 	vmbus_disconnect();
 	hv_remove_vmbus_irq();
 	for_each_online_cpu(cpu) {
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
new file mode 100644
index 000000000000..0cd73f7bc992
--- /dev/null
+++ b/include/clocksource/hyperv_timer.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Definitions for the clocksource provided by the Hyper-V
+ * hypervisor to guest VMs, as described in the Hyper-V Top
+ * Level Functional Spec (TLFS).
+ *
+ * Copyright (C) 2019, Microsoft, Inc.
+ *
+ * Author:  Michael Kelley <mikelley@microsoft.com>
+ */
+
+#ifndef __CLKSOURCE_HYPERV_TIMER_H
+#define __CLKSOURCE_HYPERV_TIMER_H
+
+#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
+#define HV_MIN_DELTA_TICKS 1
+
+/* Routines called by the VMbus driver */
+extern int hv_stimer_alloc(int sint);
+extern void hv_stimer_free(void);
+extern void hv_stimer_init(unsigned int cpu);
+extern void hv_stimer_cleanup(unsigned int cpu);
+extern void hv_stimer_global_cleanup(void);
+extern void hv_stimer0_isr(void);
+
+#endif

RE: [tip:timers/core] clocksource/drivers: Make Hyper-V clocksource ISA agnostic

[Dexuan Cui]

> From: linux-hyperv-owner@vger.kernel.org
> <linux-hyperv-owner@vger.kernel.org> On Behalf Of tip-bot for Michael Kelley
> Sent: Wednesday, July 3, 2019 2:07 AM
> clocksource/drivers: Make Hyper-V clocksource ISA agnostic
> 
> Hyper-V clock/timer code and data structures are currently mixed
> in with other code in the ISA independent drivers/hv directory as
> well as the ISA dependent Hyper-V code under arch/x86.
> 
> Consolidate this code and data structures into a Hyper-V clocksource driver
> to better follow the Linux model. In doing so, separate out the ISA
> dependent portions so the new clocksource driver works for x86 and for the
> in-process Hyper-V on ARM64 code.
> 
> To start, move the existing clockevents code to create the new clocksource
> driver. Update the VMbus driver to call initialization and cleanup routines
> since the Hyper-V synthetic timers are not independently enumerated in
> ACPI.
> 
> No behavior is changed and no new functionality is added.
>... 
> +void hv_stimer_cleanup(unsigned int cpu)
> +{
> +	struct clock_event_device *ce;
> +
> +	/* Turn off clockevent device */
> +	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
> +		ce = per_cpu_ptr(hv_clock_event, cpu);
> +		hv_ce_shutdown(ce);
> +	}
> +}

Actually, there is a behavior change (see https://lkml.org/lkml/2019/7/1/9):
	Removed call to clockevents_unbind_device() [Thomas Gleixner]
and this breaks my ongoing work of Linux guest hibernation on Hyper-V. :-(

I guess Thomas suggested we remove the call because the clockevent device
can be automatically cleaned up in tick_cleanup_dead_cpu(), when a CPU is 
offlined? BTW, I didn't find Thomas's mail suggesting the change.

In the case of hibernation, this is not true for CPU0, because 
tick_cleanup_dead_cpu() is not called for CPU0. As a result, when the
system resumes from hibernation, we add the same clock_event_device
into the global list clockevent_devices twice in hv_stimer_init(0) ->
clockevents_config_and_register() for CPU0, causing unexpected
behaviors...

Should we call clockevents_unbind_device() or tick_cleanup_dead_cpu()
somewher for CPU0, in the case of hibernation? 

Or, in clockevents_config_and_register(), should we not add the event
device, if it's already in the global list?

Thanks,
-- Dexuan

RE: [tip:timers/core] clocksource/drivers: Make Hyper-V clocksource ISA agnostic

[Thomas Gleixner]

On Sat, 6 Jul 2019, Dexuan Cui wrote:
> > From: linux-hyperv-owner@vger.kernel.org
> > <linux-hyperv-owner@vger.kernel.org> On Behalf Of tip-bot for Michael Kelley
> > No behavior is changed and no new functionality is added.
> >... 
> > +void hv_stimer_cleanup(unsigned int cpu)
> > +{
> > +	struct clock_event_device *ce;
> > +
> > +	/* Turn off clockevent device */
> > +	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
> > +		ce = per_cpu_ptr(hv_clock_event, cpu);
> > +		hv_ce_shutdown(ce);
> > +	}
> > +}
> 
> Actually, there is a behavior change (see https://lkml.org/lkml/2019/7/1/9):
> 	Removed call to clockevents_unbind_device() [Thomas Gleixner]
> and this breaks my ongoing work of Linux guest hibernation on Hyper-V. :-(
> 
> I guess Thomas suggested we remove the call because the clockevent device
> can be automatically cleaned up in tick_cleanup_dead_cpu(), when a CPU is 
> offlined? BTW, I didn't find Thomas's mail suggesting the change.
> 
> In the case of hibernation, this is not true for CPU0, because 
> tick_cleanup_dead_cpu() is not called for CPU0. As a result, when the
> system resumes from hibernation, we add the same clock_event_device
> into the global list clockevent_devices twice in hv_stimer_init(0) ->
> clockevents_config_and_register() for CPU0, causing unexpected
> behaviors...

The way this is normally done is to suspend the clockevent device on
hibernation and resume it when coming back. From a kernel POV resume is
really different than boot.

But that needs probably more surgery. I'll add the unbind() call back for
now.

Thanks,

	tglx

RE: [tip:timers/core] clocksource/drivers: Make Hyper-V clocksource ISA agnostic

[Thomas Gleixner]

On Sat, 6 Jul 2019, Thomas Gleixner wrote:

> On Sat, 6 Jul 2019, Dexuan Cui wrote:
> > > From: linux-hyperv-owner@vger.kernel.org
> > > <linux-hyperv-owner@vger.kernel.org> On Behalf Of tip-bot for Michael Kelley
> > > No behavior is changed and no new functionality is added.
> > >... 
> > > +void hv_stimer_cleanup(unsigned int cpu)
> > > +{
> > > +	struct clock_event_device *ce;
> > > +
> > > +	/* Turn off clockevent device */
> > > +	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
> > > +		ce = per_cpu_ptr(hv_clock_event, cpu);
> > > +		hv_ce_shutdown(ce);
> > > +	}
> > > +}
> > 
> > Actually, there is a behavior change (see https://lkml.org/lkml/2019/7/1/9):
> > 	Removed call to clockevents_unbind_device() [Thomas Gleixner]
> > and this breaks my ongoing work of Linux guest hibernation on Hyper-V. :-(
> > 
> > I guess Thomas suggested we remove the call because the clockevent device
> > can be automatically cleaned up in tick_cleanup_dead_cpu(), when a CPU is 
> > offlined? BTW, I didn't find Thomas's mail suggesting the change.
> > 
> > In the case of hibernation, this is not true for CPU0, because 
> > tick_cleanup_dead_cpu() is not called for CPU0. As a result, when the
> > system resumes from hibernation, we add the same clock_event_device
> > into the global list clockevent_devices twice in hv_stimer_init(0) ->
> > clockevents_config_and_register() for CPU0, causing unexpected
> > behaviors...
> 
> The way this is normally done is to suspend the clockevent device on
> hibernation and resume it when coming back. From a kernel POV resume is
> really different than boot.
> 
> But that needs probably more surgery. I'll add the unbind() call back for
> now.

Second thoughts. As it was just on top of the branch, I dropped the two
patches and we can sort it out for 5.4 without a hurry.

Thanks,

	tglx

RE: [tip:timers/core] clocksource/drivers: Make Hyper-V clocksource ISA agnostic

[Dexuan Cui]

> From: Thomas Gleixner <tglx@linutronix.de>
> Sent: Saturday, July 6, 2019 1:34 AM
> 
> On Sat, 6 Jul 2019, Thomas Gleixner wrote:
> 
> > On Sat, 6 Jul 2019, Dexuan Cui wrote:
> > > > From: linux-hyperv-owner@vger.kernel.org
> > > > <linux-hyperv-owner@vger.kernel.org> On Behalf Of tip-bot for Michael
> Kelley
> > > > No behavior is changed and no new functionality is added.
> > > >...
> > > > +void hv_stimer_cleanup(unsigned int cpu)
> > > > +{
> > > > +	struct clock_event_device *ce;
> > > > +
> > > > +	/* Turn off clockevent device */
> > > > +	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
> > > > +		ce = per_cpu_ptr(hv_clock_event, cpu);
> > > > +		hv_ce_shutdown(ce);
> > > > +	}
> > > > +}
> > >
> > > Actually, there is a behavior change (see ...):
> > > 	Removed call to clockevents_unbind_device() [Thomas Gleixner]
> > > and this breaks my ongoing work of Linux guest hibernation on Hyper-V. :-(
> > >
> > > I guess Thomas suggested we remove the call because the clockevent
> device
> > > can be automatically cleaned up in tick_cleanup_dead_cpu(), when a CPU is
> > > offlined? BTW, I didn't find Thomas's mail suggesting the change.
> > >
> > > In the case of hibernation, this is not true for CPU0, because
> > > tick_cleanup_dead_cpu() is not called for CPU0. As a result, when the
> > > system resumes from hibernation, we add the same clock_event_device
> > > into the global list clockevent_devices twice in hv_stimer_init(0) ->
> > > clockevents_config_and_register() for CPU0, causing unexpected
> > > behaviors...
> >
> > The way this is normally done is to suspend the clockevent device on
> > hibernation and resume it when coming back. From a kernel POV resume is
> > really different than boot.

Hi Thomas,
Thanks for the important reminder! I realized actually Michael's patches are
good, and hibernation can not work because my own hibernation code is buggy:
in the resume path, on CPU0, I should NOT call hv_stimer_init() -> 
clockevents_config_and_register(): instead, I should use the event device's 
suspend/resume callbacks to save/restore the device's state.

With this kept in mind, I made some small changes to my code and hibernation
can work fine for me now!

> > But that needs probably more surgery. I'll add the unbind() call back for
> > now.

Can you please drop the unbind() call again? :-)

I realized we don't really need it, and hibernation can work for me without it.
I checked the related functions in detail: tick_cleanup_dead_cpu(), 
timekeeping_suspend() and timekeeping_resume(), and I think the unbind()
call is indeed unnecessary.

I also checked the CPU offlining scenario, and I think the unbind() call is
also unnecessary.
 
> Second thoughts. As it was just on top of the branch, I dropped the two
> patches and we can sort it out for 5.4 without a hurry.
> 
> 	tglx

Hmm, I'm sorry for providing misleading info in my previous mail.
IMHO I really think the 2 patches are good. They have been there quite
a while and it's already the 5th version. I hope they can be in 5.3-rc1 so
life would be a lot easier for everyone. :-) Especially, my hiberation work
has been rebased onto the 2 patches; if they can not be in 5.3, I'll have
to rebase my code again and once my code is accepted, it would make
it harder to rebase the 2 patches.

May I know if there is any concern about the 2 patches? If yes, I 
definitely want to help sort it out now.

Thanks,
-- Dexuan

RE: [tip:timers/core] clocksource/drivers: Make Hyper-V clocksource ISA agnostic

[Thomas Gleixner]

On Sat, 6 Jul 2019, Dexuan Cui wrote:
> > On Sat, 6 Jul 2019, Thomas Gleixner wrote:
> Hi Thomas,
> Thanks for the important reminder! I realized actually Michael's patches are
> good, and hibernation can not work because my own hibernation code is buggy:
> in the resume path, on CPU0, I should NOT call hv_stimer_init() -> 
> clockevents_config_and_register(): instead, I should use the event device's 
> suspend/resume callbacks to save/restore the device's state.
> 
> With this kept in mind, I made some small changes to my code and hibernation
> can work fine for me now!
> 
> > > But that needs probably more surgery. I'll add the unbind() call back for
> > > now.
> 
> Can you please drop the unbind() call again? :-)

I restored the original commits without the unbind. All good now :)

[PATCH v5 2/2] clocksource/drivers: Continue making Hyper-V clocksource ISA agnostic

[Michael Kelley]

Continue consolidating Hyper-V clock and timer code into an ISA
independent Hyper-V clocksource driver. Move the existing clocksource
code under drivers/hv and arch/x86 to the new clocksource driver
while separating out the ISA dependencies. Update Hyper-V
initialization to call initialization and cleanup routines since the
Hyper-V synthetic clock is not independently enumerated in ACPI.
Update Hyper-V clocksource users in KVM and VDSO to get definitions
from a new include file.

No behavior is changed and no new functionality is added.

Suggested-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
---
 arch/x86/entry/vdso/vma.c                |   2 +-
 arch/x86/hyperv/hv_init.c                |  91 +-------------------
 arch/x86/include/asm/mshyperv.h          |  81 +++---------------
 arch/x86/include/asm/vdso/gettimeofday.h |   2 +-
 arch/x86/kvm/x86.c                       |   1 +
 drivers/clocksource/hyperv_timer.c       | 139 +++++++++++++++++++++++++++++++
 drivers/hv/hv_util.c                     |   1 +
 include/clocksource/hyperv_timer.h       |  78 +++++++++++++++++
 8 files changed, 235 insertions(+), 160 deletions(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 8db1f59..349a61d 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -22,7 +22,7 @@
 #include <asm/page.h>
 #include <asm/desc.h>
 #include <asm/cpufeature.h>
-#include <asm/mshyperv.h>
+#include <clocksource/hyperv_timer.h>
 
 #if defined(CONFIG_X86_64)
 unsigned int __read_mostly vdso64_enabled = 1;
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 1608050..0e033ef 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -17,64 +17,13 @@
 #include <linux/version.h>
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
-#include <linux/clockchips.h>
 #include <linux/hyperv.h>
 #include <linux/slab.h>
 #include <linux/cpuhotplug.h>
-
-#ifdef CONFIG_HYPERV_TSCPAGE
-
-static struct ms_hyperv_tsc_page *tsc_pg;
-
-struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
-{
-	return tsc_pg;
-}
-EXPORT_SYMBOL_GPL(hv_get_tsc_page);
-
-static u64 read_hv_clock_tsc(struct clocksource *arg)
-{
-	u64 current_tick = hv_read_tsc_page(tsc_pg);
-
-	if (current_tick == U64_MAX)
-		rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
-
-	return current_tick;
-}
-
-static struct clocksource hyperv_cs_tsc = {
-		.name		= "hyperv_clocksource_tsc_page",
-		.rating		= 400,
-		.read		= read_hv_clock_tsc,
-		.mask		= CLOCKSOURCE_MASK(64),
-		.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
-};
-#endif
-
-static u64 read_hv_clock_msr(struct clocksource *arg)
-{
-	u64 current_tick;
-	/*
-	 * Read the partition counter to get the current tick count. This count
-	 * is set to 0 when the partition is created and is incremented in
-	 * 100 nanosecond units.
-	 */
-	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
-	return current_tick;
-}
-
-static struct clocksource hyperv_cs_msr = {
-	.name		= "hyperv_clocksource_msr",
-	.rating		= 400,
-	.read		= read_hv_clock_msr,
-	.mask		= CLOCKSOURCE_MASK(64),
-	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
-};
+#include <clocksource/hyperv_timer.h>
 
 void *hv_hypercall_pg;
 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
-struct clocksource *hyperv_cs;
-EXPORT_SYMBOL_GPL(hyperv_cs);
 
 u32 *hv_vp_index;
 EXPORT_SYMBOL_GPL(hv_vp_index);
@@ -343,42 +292,8 @@ void __init hyperv_init(void)
 
 	x86_init.pci.arch_init = hv_pci_init;
 
-	/*
-	 * Register Hyper-V specific clocksource.
-	 */
-#ifdef CONFIG_HYPERV_TSCPAGE
-	if (ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE) {
-		union hv_x64_msr_hypercall_contents tsc_msr;
-
-		tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
-		if (!tsc_pg)
-			goto register_msr_cs;
-
-		hyperv_cs = &hyperv_cs_tsc;
-
-		rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
-
-		tsc_msr.enable = 1;
-		tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
-
-		wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
-
-		hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
-
-		clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
-		return;
-	}
-register_msr_cs:
-#endif
-	/*
-	 * For 32 bit guests just use the MSR based mechanism for reading
-	 * the partition counter.
-	 */
-
-	hyperv_cs = &hyperv_cs_msr;
-	if (ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE)
-		clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
-
+	/* Register Hyper-V specific clocksource */
+	hv_init_clocksource();
 	return;
 
 remove_cpuhp_state:
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index cc60e61..f4fa8a9 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -105,6 +105,17 @@ static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
 #define hv_get_crash_ctl(val) \
 	rdmsrl(HV_X64_MSR_CRASH_CTL, val)
 
+#define hv_get_time_ref_count(val) \
+	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, val)
+
+#define hv_get_reference_tsc(val) \
+	rdmsrl(HV_X64_MSR_REFERENCE_TSC, val)
+#define hv_set_reference_tsc(val) \
+	wrmsrl(HV_X64_MSR_REFERENCE_TSC, val)
+#define hv_set_clocksource_vdso(val) \
+	((val).archdata.vclock_mode = VCLOCK_HVCLOCK)
+#define hv_get_raw_timer() rdtsc_ordered()
+
 void hyperv_callback_vector(void);
 void hyperv_reenlightenment_vector(void);
 #ifdef CONFIG_TRACING
@@ -133,7 +144,6 @@ static inline void hv_disable_stimer0_percpu_irq(int irq) {}
 
 
 #if IS_ENABLED(CONFIG_HYPERV)
-extern struct clocksource *hyperv_cs;
 extern void *hv_hypercall_pg;
 extern void  __percpu  **hyperv_pcpu_input_arg;
 
@@ -387,73 +397,4 @@ static inline int hyperv_flush_guest_mapping_range(u64 as,
 }
 #endif /* CONFIG_HYPERV */
 
-#ifdef CONFIG_HYPERV_TSCPAGE
-struct ms_hyperv_tsc_page *hv_get_tsc_page(void);
-static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
-				       u64 *cur_tsc)
-{
-	u64 scale, offset;
-	u32 sequence;
-
-	/*
-	 * The protocol for reading Hyper-V TSC page is specified in Hypervisor
-	 * Top-Level Functional Specification ver. 3.0 and above. To get the
-	 * reference time we must do the following:
-	 * - READ ReferenceTscSequence
-	 *   A special '0' value indicates the time source is unreliable and we
-	 *   need to use something else. The currently published specification
-	 *   versions (up to 4.0b) contain a mistake and wrongly claim '-1'
-	 *   instead of '0' as the special value, see commit c35b82ef0294.
-	 * - ReferenceTime =
-	 *        ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset
-	 * - READ ReferenceTscSequence again. In case its value has changed
-	 *   since our first reading we need to discard ReferenceTime and repeat
-	 *   the whole sequence as the hypervisor was updating the page in
-	 *   between.
-	 */
-	do {
-		sequence = READ_ONCE(tsc_pg->tsc_sequence);
-		if (!sequence)
-			return U64_MAX;
-		/*
-		 * Make sure we read sequence before we read other values from
-		 * TSC page.
-		 */
-		smp_rmb();
-
-		scale = READ_ONCE(tsc_pg->tsc_scale);
-		offset = READ_ONCE(tsc_pg->tsc_offset);
-		*cur_tsc = rdtsc_ordered();
-
-		/*
-		 * Make sure we read sequence after we read all other values
-		 * from TSC page.
-		 */
-		smp_rmb();
-
-	} while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);
-
-	return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
-}
-
-static inline u64 hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
-{
-	u64 cur_tsc;
-
-	return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
-}
-
-#else
-static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
-{
-	return NULL;
-}
-
-static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
-				       u64 *cur_tsc)
-{
-	BUG();
-	return U64_MAX;
-}
-#endif
 #endif
diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
index a14039a..ae91429 100644
--- a/arch/x86/include/asm/vdso/gettimeofday.h
+++ b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -18,7 +18,7 @@
 #include <asm/unistd.h>
 #include <asm/msr.h>
 #include <asm/pvclock.h>
-#include <asm/mshyperv.h>
+#include <clocksource/hyperv_timer.h>
 
 #define __vdso_data (VVAR(_vdso_data))
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9857992..07ddb1e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -67,6 +67,7 @@
 #include <asm/mshyperv.h>
 #include <asm/hypervisor.h>
 #include <asm/intel_pt.h>
+#include <clocksource/hyperv_timer.h>
 
 #define CREATE_TRACE_POINTS
 #include "trace.h"
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 68a28af..ba2c79e 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -14,6 +14,8 @@
 #include <linux/percpu.h>
 #include <linux/cpumask.h>
 #include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/sched_clock.h>
 #include <linux/mm.h>
 #include <clocksource/hyperv_timer.h>
 #include <asm/hyperv-tlfs.h>
@@ -198,3 +200,140 @@ void hv_stimer_global_cleanup(void)
 	hv_stimer_free();
 }
 EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
+
+/*
+ * Code and definitions for the Hyper-V clocksources.  Two
+ * clocksources are defined: one that reads the Hyper-V defined MSR, and
+ * the other that uses the TSC reference page feature as defined in the
+ * TLFS.  The MSR version is for compatibility with old versions of
+ * Hyper-V and 32-bit x86.  The TSC reference page version is preferred.
+ */
+
+struct clocksource *hyperv_cs;
+EXPORT_SYMBOL_GPL(hyperv_cs);
+
+#ifdef CONFIG_HYPERV_TSCPAGE
+
+static struct ms_hyperv_tsc_page *tsc_pg;
+
+struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
+{
+	return tsc_pg;
+}
+EXPORT_SYMBOL_GPL(hv_get_tsc_page);
+
+static u64 notrace read_hv_sched_clock_tsc(void)
+{
+	u64 current_tick = hv_read_tsc_page(tsc_pg);
+
+	if (current_tick == U64_MAX)
+		hv_get_time_ref_count(current_tick);
+
+	return current_tick;
+}
+
+static u64 read_hv_clock_tsc(struct clocksource *arg)
+{
+	return read_hv_sched_clock_tsc();
+}
+
+static struct clocksource hyperv_cs_tsc = {
+	.name	= "hyperv_clocksource_tsc_page",
+	.rating	= 400,
+	.read	= read_hv_clock_tsc,
+	.mask	= CLOCKSOURCE_MASK(64),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+#endif
+
+static u64 notrace read_hv_sched_clock_msr(void)
+{
+	u64 current_tick;
+	/*
+	 * Read the partition counter to get the current tick count. This count
+	 * is set to 0 when the partition is created and is incremented in
+	 * 100 nanosecond units.
+	 */
+	hv_get_time_ref_count(current_tick);
+	return current_tick;
+}
+
+static u64 read_hv_clock_msr(struct clocksource *arg)
+{
+	return read_hv_sched_clock_msr();
+}
+
+static struct clocksource hyperv_cs_msr = {
+	.name	= "hyperv_clocksource_msr",
+	.rating	= 400,
+	.read	= read_hv_clock_msr,
+	.mask	= CLOCKSOURCE_MASK(64),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#ifdef CONFIG_HYPERV_TSCPAGE
+static bool __init hv_init_tsc_clocksource(void)
+{
+	u64		tsc_msr;
+	phys_addr_t	phys_addr;
+
+	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
+		return false;
+
+	tsc_pg = vmalloc(PAGE_SIZE);
+	if (!tsc_pg)
+		return false;
+
+	hyperv_cs = &hyperv_cs_tsc;
+	phys_addr = page_to_phys(vmalloc_to_page(tsc_pg));
+
+	/*
+	 * The Hyper-V TLFS specifies to preserve the value of reserved
+	 * bits in registers. So read the existing value, preserve the
+	 * low order 12 bits, and add in the guest physical address
+	 * (which already has at least the low 12 bits set to zero since
+	 * it is page aligned). Also set the "enable" bit, which is bit 0.
+	 */
+	hv_get_reference_tsc(tsc_msr);
+	tsc_msr &= GENMASK_ULL(11, 0);
+	tsc_msr = tsc_msr | 0x1 | (u64)phys_addr;
+	hv_set_reference_tsc(tsc_msr);
+
+	hv_set_clocksource_vdso(hyperv_cs_tsc);
+	clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
+
+	/* sched_clock_register is needed on ARM64 but is a no-op on x86 */
+	sched_clock_register(read_hv_sched_clock_tsc, 64, HV_CLOCK_HZ);
+	return true;
+}
+#else
+static bool __init hv_init_tsc_clocksource(void)
+{
+	return false;
+}
+#endif
+
+
+void __init hv_init_clocksource(void)
+{
+	/*
+	 * Try to set up the TSC page clocksource. If it succeeds, we're
+	 * done. Otherwise, set up the MSR clocksoruce.  At least one of
+	 * these will always be available except on very old versions of
+	 * Hyper-V on x86.  In that case we won't have a Hyper-V
+	 * clocksource, but Linux will still run with a clocksource based
+	 * on the emulated PIT or LAPIC timer.
+	 */
+	if (hv_init_tsc_clocksource())
+		return;
+
+	if (!(ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE))
+		return;
+
+	hyperv_cs = &hyperv_cs_msr;
+	clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
+
+	/* sched_clock_register is needed on ARM64 but is a no-op on x86 */
+	sched_clock_register(read_hv_sched_clock_msr, 64, HV_CLOCK_HZ);
+}
+EXPORT_SYMBOL_GPL(hv_init_clocksource);
diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index 7d3d31f..e32681e 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -17,6 +17,7 @@
 #include <linux/hyperv.h>
 #include <linux/clockchips.h>
 #include <linux/ptp_clock_kernel.h>
+#include <clocksource/hyperv_timer.h>
 #include <asm/mshyperv.h>
 
 #include "hyperv_vmbus.h"
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
index 0cd73f7..ecc044d 100644
--- a/include/clocksource/hyperv_timer.h
+++ b/include/clocksource/hyperv_timer.h
@@ -13,6 +13,10 @@
 #ifndef __CLKSOURCE_HYPERV_TIMER_H
 #define __CLKSOURCE_HYPERV_TIMER_H
 
+#include <linux/clocksource.h>
+#include <linux/math64.h>
+#include <asm/mshyperv.h>
+
 #define HV_MAX_MAX_DELTA_TICKS 0xffffffff
 #define HV_MIN_DELTA_TICKS 1
 
@@ -24,4 +28,78 @@
 extern void hv_stimer_global_cleanup(void);
 extern void hv_stimer0_isr(void);
 
+#if IS_ENABLED(CONFIG_HYPERV)
+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 u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
+				       u64 *cur_tsc)
+{
+	u64 scale, offset;
+	u32 sequence;
+
+	/*
+	 * The protocol for reading Hyper-V TSC page is specified in Hypervisor
+	 * Top-Level Functional Specification ver. 3.0 and above. To get the
+	 * reference time we must do the following:
+	 * - READ ReferenceTscSequence
+	 *   A special '0' value indicates the time source is unreliable and we
+	 *   need to use something else. The currently published specification
+	 *   versions (up to 4.0b) contain a mistake and wrongly claim '-1'
+	 *   instead of '0' as the special value, see commit c35b82ef0294.
+	 * - ReferenceTime =
+	 *        ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset
+	 * - READ ReferenceTscSequence again. In case its value has changed
+	 *   since our first reading we need to discard ReferenceTime and repeat
+	 *   the whole sequence as the hypervisor was updating the page in
+	 *   between.
+	 */
+	do {
+		sequence = READ_ONCE(tsc_pg->tsc_sequence);
+		if (!sequence)
+			return U64_MAX;
+		/*
+		 * Make sure we read sequence before we read other values from
+		 * TSC page.
+		 */
+		smp_rmb();
+
+		scale = READ_ONCE(tsc_pg->tsc_scale);
+		offset = READ_ONCE(tsc_pg->tsc_offset);
+		*cur_tsc = hv_get_raw_timer();
+
+		/*
+		 * Make sure we read sequence after we read all other values
+		 * from TSC page.
+		 */
+		smp_rmb();
+
+	} while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);
+
+	return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
+}
+
+static inline u64 hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
+{
+	u64 cur_tsc;
+
+	return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
+}
+
+#else /* CONFIG_HYPERV_TSC_PAGE */
+static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
+{
+	return NULL;
+}
+
+static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
+				       u64 *cur_tsc)
+{
+	return U64_MAX;
+}
+#endif /* CONFIG_HYPERV_TSCPAGE */
+
 #endif
-- 
1.8.3.1

[PATCH v5 2/2] clocksource/drivers: Continue making Hyper-V clocksource ISA agnostic

[Michael Kelley]

Continue consolidating Hyper-V clock and timer code into an ISA
independent Hyper-V clocksource driver. Move the existing clocksource
code under drivers/hv and arch/x86 to the new clocksource driver
while separating out the ISA dependencies. Update Hyper-V
initialization to call initialization and cleanup routines since the
Hyper-V synthetic clock is not independently enumerated in ACPI.
Update Hyper-V clocksource users in KVM and VDSO to get definitions
from a new include file.

No behavior is changed and no new functionality is added.

Suggested-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
---
 arch/x86/entry/vdso/vma.c                |   2 +-
 arch/x86/hyperv/hv_init.c                |  91 +-------------------
 arch/x86/include/asm/mshyperv.h          |  81 +++---------------
 arch/x86/include/asm/vdso/gettimeofday.h |   2 +-
 arch/x86/kvm/x86.c                       |   1 +
 drivers/clocksource/hyperv_timer.c       | 139 +++++++++++++++++++++++++++++++
 drivers/hv/hv_util.c                     |   1 +
 include/clocksource/hyperv_timer.h       |  78 +++++++++++++++++
 8 files changed, 235 insertions(+), 160 deletions(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 8db1f59..349a61d 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -22,7 +22,7 @@
 #include <asm/page.h>
 #include <asm/desc.h>
 #include <asm/cpufeature.h>
-#include <asm/mshyperv.h>
+#include <clocksource/hyperv_timer.h>
 
 #if defined(CONFIG_X86_64)
 unsigned int __read_mostly vdso64_enabled = 1;
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 1608050..0e033ef 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -17,64 +17,13 @@
 #include <linux/version.h>
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
-#include <linux/clockchips.h>
 #include <linux/hyperv.h>
 #include <linux/slab.h>
 #include <linux/cpuhotplug.h>
-
-#ifdef CONFIG_HYPERV_TSCPAGE
-
-static struct ms_hyperv_tsc_page *tsc_pg;
-
-struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
-{
-	return tsc_pg;
-}
-EXPORT_SYMBOL_GPL(hv_get_tsc_page);
-
-static u64 read_hv_clock_tsc(struct clocksource *arg)
-{
-	u64 current_tick = hv_read_tsc_page(tsc_pg);
-
-	if (current_tick == U64_MAX)
-		rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
-
-	return current_tick;
-}
-
-static struct clocksource hyperv_cs_tsc = {
-		.name		= "hyperv_clocksource_tsc_page",
-		.rating		= 400,
-		.read		= read_hv_clock_tsc,
-		.mask		= CLOCKSOURCE_MASK(64),
-		.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
-};
-#endif
-
-static u64 read_hv_clock_msr(struct clocksource *arg)
-{
-	u64 current_tick;
-	/*
-	 * Read the partition counter to get the current tick count. This count
-	 * is set to 0 when the partition is created and is incremented in
-	 * 100 nanosecond units.
-	 */
-	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
-	return current_tick;
-}
-
-static struct clocksource hyperv_cs_msr = {
-	.name		= "hyperv_clocksource_msr",
-	.rating		= 400,
-	.read		= read_hv_clock_msr,
-	.mask		= CLOCKSOURCE_MASK(64),
-	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
-};
+#include <clocksource/hyperv_timer.h>
 
 void *hv_hypercall_pg;
 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
-struct clocksource *hyperv_cs;
-EXPORT_SYMBOL_GPL(hyperv_cs);
 
 u32 *hv_vp_index;
 EXPORT_SYMBOL_GPL(hv_vp_index);
@@ -343,42 +292,8 @@ void __init hyperv_init(void)
 
 	x86_init.pci.arch_init = hv_pci_init;
 
-	/*
-	 * Register Hyper-V specific clocksource.
-	 */
-#ifdef CONFIG_HYPERV_TSCPAGE
-	if (ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE) {
-		union hv_x64_msr_hypercall_contents tsc_msr;
-
-		tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
-		if (!tsc_pg)
-			goto register_msr_cs;
-
-		hyperv_cs = &hyperv_cs_tsc;
-
-		rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
-
-		tsc_msr.enable = 1;
-		tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
-
-		wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
-
-		hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
-
-		clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
-		return;
-	}
-register_msr_cs:
-#endif
-	/*
-	 * For 32 bit guests just use the MSR based mechanism for reading
-	 * the partition counter.
-	 */
-
-	hyperv_cs = &hyperv_cs_msr;
-	if (ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE)
-		clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
-
+	/* Register Hyper-V specific clocksource */
+	hv_init_clocksource();
 	return;
 
 remove_cpuhp_state:
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index cc60e61..f4fa8a9 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -105,6 +105,17 @@ static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
 #define hv_get_crash_ctl(val) \
 	rdmsrl(HV_X64_MSR_CRASH_CTL, val)
 
+#define hv_get_time_ref_count(val) \
+	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, val)
+
+#define hv_get_reference_tsc(val) \
+	rdmsrl(HV_X64_MSR_REFERENCE_TSC, val)
+#define hv_set_reference_tsc(val) \
+	wrmsrl(HV_X64_MSR_REFERENCE_TSC, val)
+#define hv_set_clocksource_vdso(val) \
+	((val).archdata.vclock_mode = VCLOCK_HVCLOCK)
+#define hv_get_raw_timer() rdtsc_ordered()
+
 void hyperv_callback_vector(void);
 void hyperv_reenlightenment_vector(void);
 #ifdef CONFIG_TRACING
@@ -133,7 +144,6 @@ static inline void hv_disable_stimer0_percpu_irq(int irq) {}
 
 
 #if IS_ENABLED(CONFIG_HYPERV)
-extern struct clocksource *hyperv_cs;
 extern void *hv_hypercall_pg;
 extern void  __percpu  **hyperv_pcpu_input_arg;
 
@@ -387,73 +397,4 @@ static inline int hyperv_flush_guest_mapping_range(u64 as,
 }
 #endif /* CONFIG_HYPERV */
 
-#ifdef CONFIG_HYPERV_TSCPAGE
-struct ms_hyperv_tsc_page *hv_get_tsc_page(void);
-static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
-				       u64 *cur_tsc)
-{
-	u64 scale, offset;
-	u32 sequence;
-
-	/*
-	 * The protocol for reading Hyper-V TSC page is specified in Hypervisor
-	 * Top-Level Functional Specification ver. 3.0 and above. To get the
-	 * reference time we must do the following:
-	 * - READ ReferenceTscSequence
-	 *   A special '0' value indicates the time source is unreliable and we
-	 *   need to use something else. The currently published specification
-	 *   versions (up to 4.0b) contain a mistake and wrongly claim '-1'
-	 *   instead of '0' as the special value, see commit c35b82ef0294.
-	 * - ReferenceTime =
-	 *        ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset
-	 * - READ ReferenceTscSequence again. In case its value has changed
-	 *   since our first reading we need to discard ReferenceTime and repeat
-	 *   the whole sequence as the hypervisor was updating the page in
-	 *   between.
-	 */
-	do {
-		sequence = READ_ONCE(tsc_pg->tsc_sequence);
-		if (!sequence)
-			return U64_MAX;
-		/*
-		 * Make sure we read sequence before we read other values from
-		 * TSC page.
-		 */
-		smp_rmb();
-
-		scale = READ_ONCE(tsc_pg->tsc_scale);
-		offset = READ_ONCE(tsc_pg->tsc_offset);
-		*cur_tsc = rdtsc_ordered();
-
-		/*
-		 * Make sure we read sequence after we read all other values
-		 * from TSC page.
-		 */
-		smp_rmb();
-
-	} while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);
-
-	return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
-}
-
-static inline u64 hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
-{
-	u64 cur_tsc;
-
-	return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
-}
-
-#else
-static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
-{
-	return NULL;
-}
-
-static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
-				       u64 *cur_tsc)
-{
-	BUG();
-	return U64_MAX;
-}
-#endif
 #endif
diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
index a14039a..ae91429 100644
--- a/arch/x86/include/asm/vdso/gettimeofday.h
+++ b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -18,7 +18,7 @@
 #include <asm/unistd.h>
 #include <asm/msr.h>
 #include <asm/pvclock.h>
-#include <asm/mshyperv.h>
+#include <clocksource/hyperv_timer.h>
 
 #define __vdso_data (VVAR(_vdso_data))
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9857992..07ddb1e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -67,6 +67,7 @@
 #include <asm/mshyperv.h>
 #include <asm/hypervisor.h>
 #include <asm/intel_pt.h>
+#include <clocksource/hyperv_timer.h>
 
 #define CREATE_TRACE_POINTS
 #include "trace.h"
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 68a28af..ba2c79e 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -14,6 +14,8 @@
 #include <linux/percpu.h>
 #include <linux/cpumask.h>
 #include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/sched_clock.h>
 #include <linux/mm.h>
 #include <clocksource/hyperv_timer.h>
 #include <asm/hyperv-tlfs.h>
@@ -198,3 +200,140 @@ void hv_stimer_global_cleanup(void)
 	hv_stimer_free();
 }
 EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
+
+/*
+ * Code and definitions for the Hyper-V clocksources.  Two
+ * clocksources are defined: one that reads the Hyper-V defined MSR, and
+ * the other that uses the TSC reference page feature as defined in the
+ * TLFS.  The MSR version is for compatibility with old versions of
+ * Hyper-V and 32-bit x86.  The TSC reference page version is preferred.
+ */
+
+struct clocksource *hyperv_cs;
+EXPORT_SYMBOL_GPL(hyperv_cs);
+
+#ifdef CONFIG_HYPERV_TSCPAGE
+
+static struct ms_hyperv_tsc_page *tsc_pg;
+
+struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
+{
+	return tsc_pg;
+}
+EXPORT_SYMBOL_GPL(hv_get_tsc_page);
+
+static u64 notrace read_hv_sched_clock_tsc(void)
+{
+	u64 current_tick = hv_read_tsc_page(tsc_pg);
+
+	if (current_tick == U64_MAX)
+		hv_get_time_ref_count(current_tick);
+
+	return current_tick;
+}
+
+static u64 read_hv_clock_tsc(struct clocksource *arg)
+{
+	return read_hv_sched_clock_tsc();
+}
+
+static struct clocksource hyperv_cs_tsc = {
+	.name	= "hyperv_clocksource_tsc_page",
+	.rating	= 400,
+	.read	= read_hv_clock_tsc,
+	.mask	= CLOCKSOURCE_MASK(64),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+#endif
+
+static u64 notrace read_hv_sched_clock_msr(void)
+{
+	u64 current_tick;
+	/*
+	 * Read the partition counter to get the current tick count. This count
+	 * is set to 0 when the partition is created and is incremented in
+	 * 100 nanosecond units.
+	 */
+	hv_get_time_ref_count(current_tick);
+	return current_tick;
+}
+
+static u64 read_hv_clock_msr(struct clocksource *arg)
+{
+	return read_hv_sched_clock_msr();
+}
+
+static struct clocksource hyperv_cs_msr = {
+	.name	= "hyperv_clocksource_msr",
+	.rating	= 400,
+	.read	= read_hv_clock_msr,
+	.mask	= CLOCKSOURCE_MASK(64),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#ifdef CONFIG_HYPERV_TSCPAGE
+static bool __init hv_init_tsc_clocksource(void)
+{
+	u64		tsc_msr;
+	phys_addr_t	phys_addr;
+
+	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
+		return false;
+
+	tsc_pg = vmalloc(PAGE_SIZE);
+	if (!tsc_pg)
+		return false;
+
+	hyperv_cs = &hyperv_cs_tsc;
+	phys_addr = page_to_phys(vmalloc_to_page(tsc_pg));
+
+	/*
+	 * The Hyper-V TLFS specifies to preserve the value of reserved
+	 * bits in registers. So read the existing value, preserve the
+	 * low order 12 bits, and add in the guest physical address
+	 * (which already has at least the low 12 bits set to zero since
+	 * it is page aligned). Also set the "enable" bit, which is bit 0.
+	 */
+	hv_get_reference_tsc(tsc_msr);
+	tsc_msr &= GENMASK_ULL(11, 0);
+	tsc_msr = tsc_msr | 0x1 | (u64)phys_addr;
+	hv_set_reference_tsc(tsc_msr);
+
+	hv_set_clocksource_vdso(hyperv_cs_tsc);
+	clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
+
+	/* sched_clock_register is needed on ARM64 but is a no-op on x86 */
+	sched_clock_register(read_hv_sched_clock_tsc, 64, HV_CLOCK_HZ);
+	return true;
+}
+#else
+static bool __init hv_init_tsc_clocksource(void)
+{
+	return false;
+}
+#endif
+
+
+void __init hv_init_clocksource(void)
+{
+	/*
+	 * Try to set up the TSC page clocksource. If it succeeds, we're
+	 * done. Otherwise, set up the MSR clocksoruce.  At least one of
+	 * these will always be available except on very old versions of
+	 * Hyper-V on x86.  In that case we won't have a Hyper-V
+	 * clocksource, but Linux will still run with a clocksource based
+	 * on the emulated PIT or LAPIC timer.
+	 */
+	if (hv_init_tsc_clocksource())
+		return;
+
+	if (!(ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE))
+		return;
+
+	hyperv_cs = &hyperv_cs_msr;
+	clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
+
+	/* sched_clock_register is needed on ARM64 but is a no-op on x86 */
+	sched_clock_register(read_hv_sched_clock_msr, 64, HV_CLOCK_HZ);
+}
+EXPORT_SYMBOL_GPL(hv_init_clocksource);
diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index 7d3d31f..e32681e 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -17,6 +17,7 @@
 #include <linux/hyperv.h>
 #include <linux/clockchips.h>
 #include <linux/ptp_clock_kernel.h>
+#include <clocksource/hyperv_timer.h>
 #include <asm/mshyperv.h>
 
 #include "hyperv_vmbus.h"
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
index 0cd73f7..ecc044d 100644
--- a/include/clocksource/hyperv_timer.h
+++ b/include/clocksource/hyperv_timer.h
@@ -13,6 +13,10 @@
 #ifndef __CLKSOURCE_HYPERV_TIMER_H
 #define __CLKSOURCE_HYPERV_TIMER_H
 
+#include <linux/clocksource.h>
+#include <linux/math64.h>
+#include <asm/mshyperv.h>
+
 #define HV_MAX_MAX_DELTA_TICKS 0xffffffff
 #define HV_MIN_DELTA_TICKS 1
 
@@ -24,4 +28,78 @@
 extern void hv_stimer_global_cleanup(void);
 extern void hv_stimer0_isr(void);
 
+#if IS_ENABLED(CONFIG_HYPERV)
+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 u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
+				       u64 *cur_tsc)
+{
+	u64 scale, offset;
+	u32 sequence;
+
+	/*
+	 * The protocol for reading Hyper-V TSC page is specified in Hypervisor
+	 * Top-Level Functional Specification ver. 3.0 and above. To get the
+	 * reference time we must do the following:
+	 * - READ ReferenceTscSequence
+	 *   A special '0' value indicates the time source is unreliable and we
+	 *   need to use something else. The currently published specification
+	 *   versions (up to 4.0b) contain a mistake and wrongly claim '-1'
+	 *   instead of '0' as the special value, see commit c35b82ef0294.
+	 * - ReferenceTime =
+	 *        ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset
+	 * - READ ReferenceTscSequence again. In case its value has changed
+	 *   since our first reading we need to discard ReferenceTime and repeat
+	 *   the whole sequence as the hypervisor was updating the page in
+	 *   between.
+	 */
+	do {
+		sequence = READ_ONCE(tsc_pg->tsc_sequence);
+		if (!sequence)
+			return U64_MAX;
+		/*
+		 * Make sure we read sequence before we read other values from
+		 * TSC page.
+		 */
+		smp_rmb();
+
+		scale = READ_ONCE(tsc_pg->tsc_scale);
+		offset = READ_ONCE(tsc_pg->tsc_offset);
+		*cur_tsc = hv_get_raw_timer();
+
+		/*
+		 * Make sure we read sequence after we read all other values
+		 * from TSC page.
+		 */
+		smp_rmb();
+
+	} while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);
+
+	return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
+}
+
+static inline u64 hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
+{
+	u64 cur_tsc;
+
+	return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
+}
+
+#else /* CONFIG_HYPERV_TSC_PAGE */
+static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
+{
+	return NULL;
+}
+
+static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
+				       u64 *cur_tsc)
+{
+	return U64_MAX;
+}
+#endif /* CONFIG_HYPERV_TSCPAGE */
+
 #endif
-- 
1.8.3.1

[tip:timers/core] clocksource/drivers: Continue making Hyper-V clocksource ISA agnostic

[tip-bot for Michael Kelley]

Commit-ID:  dd2cb348613b44f9d948b068775e159aad298599
Gitweb:     https://git.kernel.org/tip/dd2cb348613b44f9d948b068775e159aad298599
Author:     Michael Kelley <mikelley@microsoft.com>
AuthorDate: Mon, 1 Jul 2019 04:26:06 +0000
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 3 Jul 2019 11:00:59 +0200

clocksource/drivers: Continue making Hyper-V clocksource ISA agnostic

Continue consolidating Hyper-V clock and timer code into an ISA
independent Hyper-V clocksource driver.

Move the existing clocksource code under drivers/hv and arch/x86 to the new
clocksource driver while separating out the ISA dependencies. Update
Hyper-V initialization to call initialization and cleanup routines since
the Hyper-V synthetic clock is not independently enumerated in ACPI.

Update Hyper-V clocksource users in KVM and VDSO to get definitions from
the new include file.

No behavior is changed and no new functionality is added.

Suggested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: "bp@alien8.de" <bp@alien8.de>
Cc: "will.deacon@arm.com" <will.deacon@arm.com>
Cc: "catalin.marinas@arm.com" <catalin.marinas@arm.com>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>
Cc: "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Cc: "olaf@aepfle.de" <olaf@aepfle.de>
Cc: "apw@canonical.com" <apw@canonical.com>
Cc: "jasowang@redhat.com" <jasowang@redhat.com>
Cc: "marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>
Cc: Sunil Muthuswamy <sunilmut@microsoft.com>
Cc: KY Srinivasan <kys@microsoft.com>
Cc: "sashal@kernel.org" <sashal@kernel.org>
Cc: "vincenzo.frascino@arm.com" <vincenzo.frascino@arm.com>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Cc: "linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>
Cc: "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>
Cc: "arnd@arndb.de" <arnd@arndb.de>
Cc: "linux@armlinux.org.uk" <linux@armlinux.org.uk>
Cc: "ralf@linux-mips.org" <ralf@linux-mips.org>
Cc: "paul.burton@mips.com" <paul.burton@mips.com>
Cc: "daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>
Cc: "salyzyn@android.com" <salyzyn@android.com>
Cc: "pcc@google.com" <pcc@google.com>
Cc: "shuah@kernel.org" <shuah@kernel.org>
Cc: "0x7f454c46@gmail.com" <0x7f454c46@gmail.com>
Cc: "linux@rasmusvillemoes.dk" <linux@rasmusvillemoes.dk>
Cc: "huw@codeweavers.com" <huw@codeweavers.com>
Cc: "sfr@canb.auug.org.au" <sfr@canb.auug.org.au>
Cc: "pbonzini@redhat.com" <pbonzini@redhat.com>
Cc: "rkrcmar@redhat.com" <rkrcmar@redhat.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Link: https://lkml.kernel.org/r/1561955054-1838-3-git-send-email-mikelley@microsoft.com

---
 arch/x86/entry/vdso/vma.c                |   2 +-
 arch/x86/hyperv/hv_init.c                |  91 +-------------------
 arch/x86/include/asm/mshyperv.h          |  81 +++---------------
 arch/x86/include/asm/vdso/gettimeofday.h |   2 +-
 arch/x86/kvm/x86.c                       |   1 +
 drivers/clocksource/hyperv_timer.c       | 139 +++++++++++++++++++++++++++++++
 drivers/hv/hv_util.c                     |   1 +
 include/clocksource/hyperv_timer.h       |  80 ++++++++++++++++++
 8 files changed, 237 insertions(+), 160 deletions(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 8db1f594e8b1..349a61d8bf34 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -22,7 +22,7 @@
 #include <asm/page.h>
 #include <asm/desc.h>
 #include <asm/cpufeature.h>
-#include <asm/mshyperv.h>
+#include <clocksource/hyperv_timer.h>
 
 #if defined(CONFIG_X86_64)
 unsigned int __read_mostly vdso64_enabled = 1;
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 1608050e9df9..0e033ef11a9f 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -17,64 +17,13 @@
 #include <linux/version.h>
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
-#include <linux/clockchips.h>
 #include <linux/hyperv.h>
 #include <linux/slab.h>
 #include <linux/cpuhotplug.h>
-
-#ifdef CONFIG_HYPERV_TSCPAGE
-
-static struct ms_hyperv_tsc_page *tsc_pg;
-
-struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
-{
-	return tsc_pg;
-}
-EXPORT_SYMBOL_GPL(hv_get_tsc_page);
-
-static u64 read_hv_clock_tsc(struct clocksource *arg)
-{
-	u64 current_tick = hv_read_tsc_page(tsc_pg);
-
-	if (current_tick == U64_MAX)
-		rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
-
-	return current_tick;
-}
-
-static struct clocksource hyperv_cs_tsc = {
-		.name		= "hyperv_clocksource_tsc_page",
-		.rating		= 400,
-		.read		= read_hv_clock_tsc,
-		.mask		= CLOCKSOURCE_MASK(64),
-		.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
-};
-#endif
-
-static u64 read_hv_clock_msr(struct clocksource *arg)
-{
-	u64 current_tick;
-	/*
-	 * Read the partition counter to get the current tick count. This count
-	 * is set to 0 when the partition is created and is incremented in
-	 * 100 nanosecond units.
-	 */
-	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
-	return current_tick;
-}
-
-static struct clocksource hyperv_cs_msr = {
-	.name		= "hyperv_clocksource_msr",
-	.rating		= 400,
-	.read		= read_hv_clock_msr,
-	.mask		= CLOCKSOURCE_MASK(64),
-	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
-};
+#include <clocksource/hyperv_timer.h>
 
 void *hv_hypercall_pg;
 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
-struct clocksource *hyperv_cs;
-EXPORT_SYMBOL_GPL(hyperv_cs);
 
 u32 *hv_vp_index;
 EXPORT_SYMBOL_GPL(hv_vp_index);
@@ -343,42 +292,8 @@ void __init hyperv_init(void)
 
 	x86_init.pci.arch_init = hv_pci_init;
 
-	/*
-	 * Register Hyper-V specific clocksource.
-	 */
-#ifdef CONFIG_HYPERV_TSCPAGE
-	if (ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE) {
-		union hv_x64_msr_hypercall_contents tsc_msr;
-
-		tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
-		if (!tsc_pg)
-			goto register_msr_cs;
-
-		hyperv_cs = &hyperv_cs_tsc;
-
-		rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
-
-		tsc_msr.enable = 1;
-		tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
-
-		wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
-
-		hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
-
-		clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
-		return;
-	}
-register_msr_cs:
-#endif
-	/*
-	 * For 32 bit guests just use the MSR based mechanism for reading
-	 * the partition counter.
-	 */
-
-	hyperv_cs = &hyperv_cs_msr;
-	if (ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE)
-		clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
-
+	/* Register Hyper-V specific clocksource */
+	hv_init_clocksource();
 	return;
 
 remove_cpuhp_state:
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index cc60e617931c..f4fa8a9d5d0b 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -105,6 +105,17 @@ static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
 #define hv_get_crash_ctl(val) \
 	rdmsrl(HV_X64_MSR_CRASH_CTL, val)
 
+#define hv_get_time_ref_count(val) \
+	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, val)
+
+#define hv_get_reference_tsc(val) \
+	rdmsrl(HV_X64_MSR_REFERENCE_TSC, val)
+#define hv_set_reference_tsc(val) \
+	wrmsrl(HV_X64_MSR_REFERENCE_TSC, val)
+#define hv_set_clocksource_vdso(val) \
+	((val).archdata.vclock_mode = VCLOCK_HVCLOCK)
+#define hv_get_raw_timer() rdtsc_ordered()
+
 void hyperv_callback_vector(void);
 void hyperv_reenlightenment_vector(void);
 #ifdef CONFIG_TRACING
@@ -133,7 +144,6 @@ static inline void hv_disable_stimer0_percpu_irq(int irq) {}
 
 
 #if IS_ENABLED(CONFIG_HYPERV)
-extern struct clocksource *hyperv_cs;
 extern void *hv_hypercall_pg;
 extern void  __percpu  **hyperv_pcpu_input_arg;
 
@@ -387,73 +397,4 @@ static inline int hyperv_flush_guest_mapping_range(u64 as,
 }
 #endif /* CONFIG_HYPERV */
 
-#ifdef CONFIG_HYPERV_TSCPAGE
-struct ms_hyperv_tsc_page *hv_get_tsc_page(void);
-static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
-				       u64 *cur_tsc)
-{
-	u64 scale, offset;
-	u32 sequence;
-
-	/*
-	 * The protocol for reading Hyper-V TSC page is specified in Hypervisor
-	 * Top-Level Functional Specification ver. 3.0 and above. To get the
-	 * reference time we must do the following:
-	 * - READ ReferenceTscSequence
-	 *   A special '0' value indicates the time source is unreliable and we
-	 *   need to use something else. The currently published specification
-	 *   versions (up to 4.0b) contain a mistake and wrongly claim '-1'
-	 *   instead of '0' as the special value, see commit c35b82ef0294.
-	 * - ReferenceTime =
-	 *        ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset
-	 * - READ ReferenceTscSequence again. In case its value has changed
-	 *   since our first reading we need to discard ReferenceTime and repeat
-	 *   the whole sequence as the hypervisor was updating the page in
-	 *   between.
-	 */
-	do {
-		sequence = READ_ONCE(tsc_pg->tsc_sequence);
-		if (!sequence)
-			return U64_MAX;
-		/*
-		 * Make sure we read sequence before we read other values from
-		 * TSC page.
-		 */
-		smp_rmb();
-
-		scale = READ_ONCE(tsc_pg->tsc_scale);
-		offset = READ_ONCE(tsc_pg->tsc_offset);
-		*cur_tsc = rdtsc_ordered();
-
-		/*
-		 * Make sure we read sequence after we read all other values
-		 * from TSC page.
-		 */
-		smp_rmb();
-
-	} while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);
-
-	return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
-}
-
-static inline u64 hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
-{
-	u64 cur_tsc;
-
-	return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
-}
-
-#else
-static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
-{
-	return NULL;
-}
-
-static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
-				       u64 *cur_tsc)
-{
-	BUG();
-	return U64_MAX;
-}
-#endif
 #endif
diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
index a14039a59abd..ae91429129a6 100644
--- a/arch/x86/include/asm/vdso/gettimeofday.h
+++ b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -18,7 +18,7 @@
 #include <asm/unistd.h>
 #include <asm/msr.h>
 #include <asm/pvclock.h>
-#include <asm/mshyperv.h>
+#include <clocksource/hyperv_timer.h>
 
 #define __vdso_data (VVAR(_vdso_data))
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8ec676029365..5e1db26b5e15 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -67,6 +67,7 @@
 #include <asm/mshyperv.h>
 #include <asm/hypervisor.h>
 #include <asm/intel_pt.h>
+#include <clocksource/hyperv_timer.h>
 
 #define CREATE_TRACE_POINTS
 #include "trace.h"
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 68a28af31561..ba2c79e6a0ee 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -14,6 +14,8 @@
 #include <linux/percpu.h>
 #include <linux/cpumask.h>
 #include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/sched_clock.h>
 #include <linux/mm.h>
 #include <clocksource/hyperv_timer.h>
 #include <asm/hyperv-tlfs.h>
@@ -198,3 +200,140 @@ void hv_stimer_global_cleanup(void)
 	hv_stimer_free();
 }
 EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
+
+/*
+ * Code and definitions for the Hyper-V clocksources.  Two
+ * clocksources are defined: one that reads the Hyper-V defined MSR, and
+ * the other that uses the TSC reference page feature as defined in the
+ * TLFS.  The MSR version is for compatibility with old versions of
+ * Hyper-V and 32-bit x86.  The TSC reference page version is preferred.
+ */
+
+struct clocksource *hyperv_cs;
+EXPORT_SYMBOL_GPL(hyperv_cs);
+
+#ifdef CONFIG_HYPERV_TSCPAGE
+
+static struct ms_hyperv_tsc_page *tsc_pg;
+
+struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
+{
+	return tsc_pg;
+}
+EXPORT_SYMBOL_GPL(hv_get_tsc_page);
+
+static u64 notrace read_hv_sched_clock_tsc(void)
+{
+	u64 current_tick = hv_read_tsc_page(tsc_pg);
+
+	if (current_tick == U64_MAX)
+		hv_get_time_ref_count(current_tick);
+
+	return current_tick;
+}
+
+static u64 read_hv_clock_tsc(struct clocksource *arg)
+{
+	return read_hv_sched_clock_tsc();
+}
+
+static struct clocksource hyperv_cs_tsc = {
+	.name	= "hyperv_clocksource_tsc_page",
+	.rating	= 400,
+	.read	= read_hv_clock_tsc,
+	.mask	= CLOCKSOURCE_MASK(64),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+#endif
+
+static u64 notrace read_hv_sched_clock_msr(void)
+{
+	u64 current_tick;
+	/*
+	 * Read the partition counter to get the current tick count. This count
+	 * is set to 0 when the partition is created and is incremented in
+	 * 100 nanosecond units.
+	 */
+	hv_get_time_ref_count(current_tick);
+	return current_tick;
+}
+
+static u64 read_hv_clock_msr(struct clocksource *arg)
+{
+	return read_hv_sched_clock_msr();
+}
+
+static struct clocksource hyperv_cs_msr = {
+	.name	= "hyperv_clocksource_msr",
+	.rating	= 400,
+	.read	= read_hv_clock_msr,
+	.mask	= CLOCKSOURCE_MASK(64),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#ifdef CONFIG_HYPERV_TSCPAGE
+static bool __init hv_init_tsc_clocksource(void)
+{
+	u64		tsc_msr;
+	phys_addr_t	phys_addr;
+
+	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
+		return false;
+
+	tsc_pg = vmalloc(PAGE_SIZE);
+	if (!tsc_pg)
+		return false;
+
+	hyperv_cs = &hyperv_cs_tsc;
+	phys_addr = page_to_phys(vmalloc_to_page(tsc_pg));
+
+	/*
+	 * The Hyper-V TLFS specifies to preserve the value of reserved
+	 * bits in registers. So read the existing value, preserve the
+	 * low order 12 bits, and add in the guest physical address
+	 * (which already has at least the low 12 bits set to zero since
+	 * it is page aligned). Also set the "enable" bit, which is bit 0.
+	 */
+	hv_get_reference_tsc(tsc_msr);
+	tsc_msr &= GENMASK_ULL(11, 0);
+	tsc_msr = tsc_msr | 0x1 | (u64)phys_addr;
+	hv_set_reference_tsc(tsc_msr);
+
+	hv_set_clocksource_vdso(hyperv_cs_tsc);
+	clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
+
+	/* sched_clock_register is needed on ARM64 but is a no-op on x86 */
+	sched_clock_register(read_hv_sched_clock_tsc, 64, HV_CLOCK_HZ);
+	return true;
+}
+#else
+static bool __init hv_init_tsc_clocksource(void)
+{
+	return false;
+}
+#endif
+
+
+void __init hv_init_clocksource(void)
+{
+	/*
+	 * Try to set up the TSC page clocksource. If it succeeds, we're
+	 * done. Otherwise, set up the MSR clocksoruce.  At least one of
+	 * these will always be available except on very old versions of
+	 * Hyper-V on x86.  In that case we won't have a Hyper-V
+	 * clocksource, but Linux will still run with a clocksource based
+	 * on the emulated PIT or LAPIC timer.
+	 */
+	if (hv_init_tsc_clocksource())
+		return;
+
+	if (!(ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE))
+		return;
+
+	hyperv_cs = &hyperv_cs_msr;
+	clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
+
+	/* sched_clock_register is needed on ARM64 but is a no-op on x86 */
+	sched_clock_register(read_hv_sched_clock_msr, 64, HV_CLOCK_HZ);
+}
+EXPORT_SYMBOL_GPL(hv_init_clocksource);
diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index 7d3d31f099ea..e32681ee7b9f 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -17,6 +17,7 @@
 #include <linux/hyperv.h>
 #include <linux/clockchips.h>
 #include <linux/ptp_clock_kernel.h>
+#include <clocksource/hyperv_timer.h>
 #include <asm/mshyperv.h>
 
 #include "hyperv_vmbus.h"
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
index 0cd73f7bc992..a821deb8ecb2 100644
--- a/include/clocksource/hyperv_timer.h
+++ b/include/clocksource/hyperv_timer.h
@@ -13,6 +13,10 @@
 #ifndef __CLKSOURCE_HYPERV_TIMER_H
 #define __CLKSOURCE_HYPERV_TIMER_H
 
+#include <linux/clocksource.h>
+#include <linux/math64.h>
+#include <asm/mshyperv.h>
+
 #define HV_MAX_MAX_DELTA_TICKS 0xffffffff
 #define HV_MIN_DELTA_TICKS 1
 
@@ -24,4 +28,80 @@ 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)
+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
+hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, u64 *cur_tsc)
+{
+	u64 scale, offset;
+	u32 sequence;
+
+	/*
+	 * The protocol for reading Hyper-V TSC page is specified in Hypervisor
+	 * Top-Level Functional Specification ver. 3.0 and above. To get the
+	 * reference time we must do the following:
+	 * - READ ReferenceTscSequence
+	 *   A special '0' value indicates the time source is unreliable and we
+	 *   need to use something else. The currently published specification
+	 *   versions (up to 4.0b) contain a mistake and wrongly claim '-1'
+	 *   instead of '0' as the special value, see commit c35b82ef0294.
+	 * - ReferenceTime =
+	 *        ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset
+	 * - READ ReferenceTscSequence again. In case its value has changed
+	 *   since our first reading we need to discard ReferenceTime and repeat
+	 *   the whole sequence as the hypervisor was updating the page in
+	 *   between.
+	 */
+	do {
+		sequence = READ_ONCE(tsc_pg->tsc_sequence);
+		if (!sequence)
+			return U64_MAX;
+		/*
+		 * Make sure we read sequence before we read other values from
+		 * TSC page.
+		 */
+		smp_rmb();
+
+		scale = READ_ONCE(tsc_pg->tsc_scale);
+		offset = READ_ONCE(tsc_pg->tsc_offset);
+		*cur_tsc = hv_get_raw_timer();
+
+		/*
+		 * Make sure we read sequence after we read all other values
+		 * from TSC page.
+		 */
+		smp_rmb();
+
+	} while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);
+
+	return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
+}
+
+static inline notrace u64
+hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
+{
+	u64 cur_tsc;
+
+	return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
+}
+
+#else /* CONFIG_HYPERV_TSC_PAGE */
+static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
+{
+	return NULL;
+}
+
+static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
+				       u64 *cur_tsc)
+{
+	return U64_MAX;
+}
+#endif /* CONFIG_HYPERV_TSCPAGE */
+
 #endif

[tip:timers/core] clocksource/drivers: Continue making Hyper-V clocksource ISA agnostic

[tip-bot for Michael Kelley]

Commit-ID:  dd2cb348613b44f9d948b068775e159aad298599
Gitweb:     https://git.kernel.org/tip/dd2cb348613b44f9d948b068775e159aad298599
Author:     Michael Kelley <mikelley@microsoft.com>
AuthorDate: Mon, 1 Jul 2019 04:26:06 +0000
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 3 Jul 2019 11:00:59 +0200

clocksource/drivers: Continue making Hyper-V clocksource ISA agnostic

Continue consolidating Hyper-V clock and timer code into an ISA
independent Hyper-V clocksource driver.

Move the existing clocksource code under drivers/hv and arch/x86 to the new
clocksource driver while separating out the ISA dependencies. Update
Hyper-V initialization to call initialization and cleanup routines since
the Hyper-V synthetic clock is not independently enumerated in ACPI.

Update Hyper-V clocksource users in KVM and VDSO to get definitions from
the new include file.

No behavior is changed and no new functionality is added.

Suggested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: "bp@alien8.de" <bp@alien8.de>
Cc: "will.deacon@arm.com" <will.deacon@arm.com>
Cc: "catalin.marinas@arm.com" <catalin.marinas@arm.com>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>
Cc: "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Cc: "olaf@aepfle.de" <olaf@aepfle.de>
Cc: "apw@canonical.com" <apw@canonical.com>
Cc: "jasowang@redhat.com" <jasowang@redhat.com>
Cc: "marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>
Cc: Sunil Muthuswamy <sunilmut@microsoft.com>
Cc: KY Srinivasan <kys@microsoft.com>
Cc: "sashal@kernel.org" <sashal@kernel.org>
Cc: "vincenzo.frascino@arm.com" <vincenzo.frascino@arm.com>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Cc: "linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>
Cc: "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>
Cc: "arnd@arndb.de" <arnd@arndb.de>
Cc: "linux@armlinux.org.uk" <linux@armlinux.org.uk>
Cc: "ralf@linux-mips.org" <ralf@linux-mips.org>
Cc: "paul.burton@mips.com" <paul.burton@mips.com>
Cc: "daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>
Cc: "salyzyn@android.com" <salyzyn@android.com>
Cc: "pcc@google.com" <pcc@google.com>
Cc: "shuah@kernel.org" <shuah@kernel.org>
Cc: "0x7f454c46@gmail.com" <0x7f454c46@gmail.com>
Cc: "linux@rasmusvillemoes.dk" <linux@rasmusvillemoes.dk>
Cc: "huw@codeweavers.com" <huw@codeweavers.com>
Cc: "sfr@canb.auug.org.au" <sfr@canb.auug.org.au>
Cc: "pbonzini@redhat.com" <pbonzini@redhat.com>
Cc: "rkrcmar@redhat.com" <rkrcmar@redhat.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Link: https://lkml.kernel.org/r/1561955054-1838-3-git-send-email-mikelley@microsoft.com

---
 arch/x86/entry/vdso/vma.c                |   2 +-
 arch/x86/hyperv/hv_init.c                |  91 +-------------------
 arch/x86/include/asm/mshyperv.h          |  81 +++---------------
 arch/x86/include/asm/vdso/gettimeofday.h |   2 +-
 arch/x86/kvm/x86.c                       |   1 +
 drivers/clocksource/hyperv_timer.c       | 139 +++++++++++++++++++++++++++++++
 drivers/hv/hv_util.c                     |   1 +
 include/clocksource/hyperv_timer.h       |  80 ++++++++++++++++++
 8 files changed, 237 insertions(+), 160 deletions(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 8db1f594e8b1..349a61d8bf34 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -22,7 +22,7 @@
 #include <asm/page.h>
 #include <asm/desc.h>
 #include <asm/cpufeature.h>
-#include <asm/mshyperv.h>
+#include <clocksource/hyperv_timer.h>
 
 #if defined(CONFIG_X86_64)
 unsigned int __read_mostly vdso64_enabled = 1;
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 1608050e9df9..0e033ef11a9f 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -17,64 +17,13 @@
 #include <linux/version.h>
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
-#include <linux/clockchips.h>
 #include <linux/hyperv.h>
 #include <linux/slab.h>
 #include <linux/cpuhotplug.h>
-
-#ifdef CONFIG_HYPERV_TSCPAGE
-
-static struct ms_hyperv_tsc_page *tsc_pg;
-
-struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
-{
-	return tsc_pg;
-}
-EXPORT_SYMBOL_GPL(hv_get_tsc_page);
-
-static u64 read_hv_clock_tsc(struct clocksource *arg)
-{
-	u64 current_tick = hv_read_tsc_page(tsc_pg);
-
-	if (current_tick == U64_MAX)
-		rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
-
-	return current_tick;
-}
-
-static struct clocksource hyperv_cs_tsc = {
-		.name		= "hyperv_clocksource_tsc_page",
-		.rating		= 400,
-		.read		= read_hv_clock_tsc,
-		.mask		= CLOCKSOURCE_MASK(64),
-		.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
-};
-#endif
-
-static u64 read_hv_clock_msr(struct clocksource *arg)
-{
-	u64 current_tick;
-	/*
-	 * Read the partition counter to get the current tick count. This count
-	 * is set to 0 when the partition is created and is incremented in
-	 * 100 nanosecond units.
-	 */
-	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
-	return current_tick;
-}
-
-static struct clocksource hyperv_cs_msr = {
-	.name		= "hyperv_clocksource_msr",
-	.rating		= 400,
-	.read		= read_hv_clock_msr,
-	.mask		= CLOCKSOURCE_MASK(64),
-	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
-};
+#include <clocksource/hyperv_timer.h>
 
 void *hv_hypercall_pg;
 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
-struct clocksource *hyperv_cs;
-EXPORT_SYMBOL_GPL(hyperv_cs);
 
 u32 *hv_vp_index;
 EXPORT_SYMBOL_GPL(hv_vp_index);
@@ -343,42 +292,8 @@ void __init hyperv_init(void)
 
 	x86_init.pci.arch_init = hv_pci_init;
 
-	/*
-	 * Register Hyper-V specific clocksource.
-	 */
-#ifdef CONFIG_HYPERV_TSCPAGE
-	if (ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE) {
-		union hv_x64_msr_hypercall_contents tsc_msr;
-
-		tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
-		if (!tsc_pg)
-			goto register_msr_cs;
-
-		hyperv_cs = &hyperv_cs_tsc;
-
-		rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
-
-		tsc_msr.enable = 1;
-		tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
-
-		wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
-
-		hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
-
-		clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
-		return;
-	}
-register_msr_cs:
-#endif
-	/*
-	 * For 32 bit guests just use the MSR based mechanism for reading
-	 * the partition counter.
-	 */
-
-	hyperv_cs = &hyperv_cs_msr;
-	if (ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE)
-		clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
-
+	/* Register Hyper-V specific clocksource */
+	hv_init_clocksource();
 	return;
 
 remove_cpuhp_state:
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index cc60e617931c..f4fa8a9d5d0b 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -105,6 +105,17 @@ static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
 #define hv_get_crash_ctl(val) \
 	rdmsrl(HV_X64_MSR_CRASH_CTL, val)
 
+#define hv_get_time_ref_count(val) \
+	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, val)
+
+#define hv_get_reference_tsc(val) \
+	rdmsrl(HV_X64_MSR_REFERENCE_TSC, val)
+#define hv_set_reference_tsc(val) \
+	wrmsrl(HV_X64_MSR_REFERENCE_TSC, val)
+#define hv_set_clocksource_vdso(val) \
+	((val).archdata.vclock_mode = VCLOCK_HVCLOCK)
+#define hv_get_raw_timer() rdtsc_ordered()
+
 void hyperv_callback_vector(void);
 void hyperv_reenlightenment_vector(void);
 #ifdef CONFIG_TRACING
@@ -133,7 +144,6 @@ static inline void hv_disable_stimer0_percpu_irq(int irq) {}
 
 
 #if IS_ENABLED(CONFIG_HYPERV)
-extern struct clocksource *hyperv_cs;
 extern void *hv_hypercall_pg;
 extern void  __percpu  **hyperv_pcpu_input_arg;
 
@@ -387,73 +397,4 @@ static inline int hyperv_flush_guest_mapping_range(u64 as,
 }
 #endif /* CONFIG_HYPERV */
 
-#ifdef CONFIG_HYPERV_TSCPAGE
-struct ms_hyperv_tsc_page *hv_get_tsc_page(void);
-static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
-				       u64 *cur_tsc)
-{
-	u64 scale, offset;
-	u32 sequence;
-
-	/*
-	 * The protocol for reading Hyper-V TSC page is specified in Hypervisor
-	 * Top-Level Functional Specification ver. 3.0 and above. To get the
-	 * reference time we must do the following:
-	 * - READ ReferenceTscSequence
-	 *   A special '0' value indicates the time source is unreliable and we
-	 *   need to use something else. The currently published specification
-	 *   versions (up to 4.0b) contain a mistake and wrongly claim '-1'
-	 *   instead of '0' as the special value, see commit c35b82ef0294.
-	 * - ReferenceTime =
-	 *        ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset
-	 * - READ ReferenceTscSequence again. In case its value has changed
-	 *   since our first reading we need to discard ReferenceTime and repeat
-	 *   the whole sequence as the hypervisor was updating the page in
-	 *   between.
-	 */
-	do {
-		sequence = READ_ONCE(tsc_pg->tsc_sequence);
-		if (!sequence)
-			return U64_MAX;
-		/*
-		 * Make sure we read sequence before we read other values from
-		 * TSC page.
-		 */
-		smp_rmb();
-
-		scale = READ_ONCE(tsc_pg->tsc_scale);
-		offset = READ_ONCE(tsc_pg->tsc_offset);
-		*cur_tsc = rdtsc_ordered();
-
-		/*
-		 * Make sure we read sequence after we read all other values
-		 * from TSC page.
-		 */
-		smp_rmb();
-
-	} while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);
-
-	return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
-}
-
-static inline u64 hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
-{
-	u64 cur_tsc;
-
-	return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
-}
-
-#else
-static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
-{
-	return NULL;
-}
-
-static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
-				       u64 *cur_tsc)
-{
-	BUG();
-	return U64_MAX;
-}
-#endif
 #endif
diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
index a14039a59abd..ae91429129a6 100644
--- a/arch/x86/include/asm/vdso/gettimeofday.h
+++ b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -18,7 +18,7 @@
 #include <asm/unistd.h>
 #include <asm/msr.h>
 #include <asm/pvclock.h>
-#include <asm/mshyperv.h>
+#include <clocksource/hyperv_timer.h>
 
 #define __vdso_data (VVAR(_vdso_data))
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8ec676029365..5e1db26b5e15 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -67,6 +67,7 @@
 #include <asm/mshyperv.h>
 #include <asm/hypervisor.h>
 #include <asm/intel_pt.h>
+#include <clocksource/hyperv_timer.h>
 
 #define CREATE_TRACE_POINTS
 #include "trace.h"
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 68a28af31561..ba2c79e6a0ee 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -14,6 +14,8 @@
 #include <linux/percpu.h>
 #include <linux/cpumask.h>
 #include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/sched_clock.h>
 #include <linux/mm.h>
 #include <clocksource/hyperv_timer.h>
 #include <asm/hyperv-tlfs.h>
@@ -198,3 +200,140 @@ void hv_stimer_global_cleanup(void)
 	hv_stimer_free();
 }
 EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
+
+/*
+ * Code and definitions for the Hyper-V clocksources.  Two
+ * clocksources are defined: one that reads the Hyper-V defined MSR, and
+ * the other that uses the TSC reference page feature as defined in the
+ * TLFS.  The MSR version is for compatibility with old versions of
+ * Hyper-V and 32-bit x86.  The TSC reference page version is preferred.
+ */
+
+struct clocksource *hyperv_cs;
+EXPORT_SYMBOL_GPL(hyperv_cs);
+
+#ifdef CONFIG_HYPERV_TSCPAGE
+
+static struct ms_hyperv_tsc_page *tsc_pg;
+
+struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
+{
+	return tsc_pg;
+}
+EXPORT_SYMBOL_GPL(hv_get_tsc_page);
+
+static u64 notrace read_hv_sched_clock_tsc(void)
+{
+	u64 current_tick = hv_read_tsc_page(tsc_pg);
+
+	if (current_tick == U64_MAX)
+		hv_get_time_ref_count(current_tick);
+
+	return current_tick;
+}
+
+static u64 read_hv_clock_tsc(struct clocksource *arg)
+{
+	return read_hv_sched_clock_tsc();
+}
+
+static struct clocksource hyperv_cs_tsc = {
+	.name	= "hyperv_clocksource_tsc_page",
+	.rating	= 400,
+	.read	= read_hv_clock_tsc,
+	.mask	= CLOCKSOURCE_MASK(64),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+#endif
+
+static u64 notrace read_hv_sched_clock_msr(void)
+{
+	u64 current_tick;
+	/*
+	 * Read the partition counter to get the current tick count. This count
+	 * is set to 0 when the partition is created and is incremented in
+	 * 100 nanosecond units.
+	 */
+	hv_get_time_ref_count(current_tick);
+	return current_tick;
+}
+
+static u64 read_hv_clock_msr(struct clocksource *arg)
+{
+	return read_hv_sched_clock_msr();
+}
+
+static struct clocksource hyperv_cs_msr = {
+	.name	= "hyperv_clocksource_msr",
+	.rating	= 400,
+	.read	= read_hv_clock_msr,
+	.mask	= CLOCKSOURCE_MASK(64),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#ifdef CONFIG_HYPERV_TSCPAGE
+static bool __init hv_init_tsc_clocksource(void)
+{
+	u64		tsc_msr;
+	phys_addr_t	phys_addr;
+
+	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
+		return false;
+
+	tsc_pg = vmalloc(PAGE_SIZE);
+	if (!tsc_pg)
+		return false;
+
+	hyperv_cs = &hyperv_cs_tsc;
+	phys_addr = page_to_phys(vmalloc_to_page(tsc_pg));
+
+	/*
+	 * The Hyper-V TLFS specifies to preserve the value of reserved
+	 * bits in registers. So read the existing value, preserve the
+	 * low order 12 bits, and add in the guest physical address
+	 * (which already has at least the low 12 bits set to zero since
+	 * it is page aligned). Also set the "enable" bit, which is bit 0.
+	 */
+	hv_get_reference_tsc(tsc_msr);
+	tsc_msr &= GENMASK_ULL(11, 0);
+	tsc_msr = tsc_msr | 0x1 | (u64)phys_addr;
+	hv_set_reference_tsc(tsc_msr);
+
+	hv_set_clocksource_vdso(hyperv_cs_tsc);
+	clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
+
+	/* sched_clock_register is needed on ARM64 but is a no-op on x86 */
+	sched_clock_register(read_hv_sched_clock_tsc, 64, HV_CLOCK_HZ);
+	return true;
+}
+#else
+static bool __init hv_init_tsc_clocksource(void)
+{
+	return false;
+}
+#endif
+
+
+void __init hv_init_clocksource(void)
+{
+	/*
+	 * Try to set up the TSC page clocksource. If it succeeds, we're
+	 * done. Otherwise, set up the MSR clocksoruce.  At least one of
+	 * these will always be available except on very old versions of
+	 * Hyper-V on x86.  In that case we won't have a Hyper-V
+	 * clocksource, but Linux will still run with a clocksource based
+	 * on the emulated PIT or LAPIC timer.
+	 */
+	if (hv_init_tsc_clocksource())
+		return;
+
+	if (!(ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE))
+		return;
+
+	hyperv_cs = &hyperv_cs_msr;
+	clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
+
+	/* sched_clock_register is needed on ARM64 but is a no-op on x86 */
+	sched_clock_register(read_hv_sched_clock_msr, 64, HV_CLOCK_HZ);
+}
+EXPORT_SYMBOL_GPL(hv_init_clocksource);
diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index 7d3d31f099ea..e32681ee7b9f 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -17,6 +17,7 @@
 #include <linux/hyperv.h>
 #include <linux/clockchips.h>
 #include <linux/ptp_clock_kernel.h>
+#include <clocksource/hyperv_timer.h>
 #include <asm/mshyperv.h>
 
 #include "hyperv_vmbus.h"
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
index 0cd73f7bc992..a821deb8ecb2 100644
--- a/include/clocksource/hyperv_timer.h
+++ b/include/clocksource/hyperv_timer.h
@@ -13,6 +13,10 @@
 #ifndef __CLKSOURCE_HYPERV_TIMER_H
 #define __CLKSOURCE_HYPERV_TIMER_H
 
+#include <linux/clocksource.h>
+#include <linux/math64.h>
+#include <asm/mshyperv.h>
+
 #define HV_MAX_MAX_DELTA_TICKS 0xffffffff
 #define HV_MIN_DELTA_TICKS 1
 
@@ -24,4 +28,80 @@ 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)
+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
+hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, u64 *cur_tsc)
+{
+	u64 scale, offset;
+	u32 sequence;
+
+	/*
+	 * The protocol for reading Hyper-V TSC page is specified in Hypervisor
+	 * Top-Level Functional Specification ver. 3.0 and above. To get the
+	 * reference time we must do the following:
+	 * - READ ReferenceTscSequence
+	 *   A special '0' value indicates the time source is unreliable and we
+	 *   need to use something else. The currently published specification
+	 *   versions (up to 4.0b) contain a mistake and wrongly claim '-1'
+	 *   instead of '0' as the special value, see commit c35b82ef0294.
+	 * - ReferenceTime =
+	 *        ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset
+	 * - READ ReferenceTscSequence again. In case its value has changed
+	 *   since our first reading we need to discard ReferenceTime and repeat
+	 *   the whole sequence as the hypervisor was updating the page in
+	 *   between.
+	 */
+	do {
+		sequence = READ_ONCE(tsc_pg->tsc_sequence);
+		if (!sequence)
+			return U64_MAX;
+		/*
+		 * Make sure we read sequence before we read other values from
+		 * TSC page.
+		 */
+		smp_rmb();
+
+		scale = READ_ONCE(tsc_pg->tsc_scale);
+		offset = READ_ONCE(tsc_pg->tsc_offset);
+		*cur_tsc = hv_get_raw_timer();
+
+		/*
+		 * Make sure we read sequence after we read all other values
+		 * from TSC page.
+		 */
+		smp_rmb();
+
+	} while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);
+
+	return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
+}
+
+static inline notrace u64
+hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
+{
+	u64 cur_tsc;
+
+	return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
+}
+
+#else /* CONFIG_HYPERV_TSC_PAGE */
+static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
+{
+	return NULL;
+}
+
+static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
+				       u64 *cur_tsc)
+{
+	return U64_MAX;
+}
+#endif /* CONFIG_HYPERV_TSCPAGE */
+
 #endif