drivers/hv/hv.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (c) 2009, Microsoft Corporation.
  *
  * Authors:
  *   Haiyang Zhang <haiyangz@microsoft.com>
  *   Hank Janssen  <hjanssen@microsoft.com>
  */
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/hyperv.h>
 #include <linux/version.h>
 #include <linux/random.h>
 #include <linux/clockchips.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.
  *
  * This routine must be called before any other routines in here are called
  */
 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;
 }

 /*
  * hv_post_message - Post a message using the hypervisor message IPC.
  *
  * This involves a hypercall.
  */
 int hv_post_message(union hv_connection_id connection_id,
 		  enum hv_message_type message_type,
 		  void *payload, size_t payload_size)
 {
 	struct hv_input_post_message *aligned_msg;
 	struct hv_per_cpu_context *hv_cpu;
 	u64 status;

 	if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
 		return -EMSGSIZE;

 	hv_cpu = get_cpu_ptr(hv_context.cpu_context);
 	aligned_msg = hv_cpu->post_msg_page;
 	aligned_msg->connectionid = connection_id;
 	aligned_msg->reserved = 0;
 	aligned_msg->message_type = message_type;
 	aligned_msg->payload_size = payload_size;
 	memcpy((void *)aligned_msg->payload, payload, payload_size);

 	status = hv_do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL);

 	/* Preemption must remain disabled until after the hypercall
 	 * so some other thread can't get scheduled onto this cpu and
 	 * corrupt the per-cpu post_msg_page
 	 */
 	put_cpu_ptr(hv_cpu);

 	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;
 	struct hv_per_cpu_context *hv_cpu;

 	/*
 	 * First, zero all per-cpu memory areas so hv_synic_free() can
 	 * detect what memory has been allocated and cleanup properly
 	 * after any failures.
 	 */
 	for_each_present_cpu(cpu) {
 		hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu);
 		memset(hv_cpu, 0, sizeof(*hv_cpu));
 	}

 	hv_context.hv_numa_map = kcalloc(nr_node_ids, sizeof(struct cpumask),
 					 GFP_KERNEL);
 	if (hv_context.hv_numa_map == NULL) {
 		pr_err("Unable to allocate NUMA map\n");
 		goto err;
 	}

 	for_each_present_cpu(cpu) {
 		hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu);

 		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) {
 			pr_err("Unable to allocate SYNIC message page\n");
 			goto err;
 		}

 		hv_cpu->synic_event_page = (void *)get_zeroed_page(GFP_ATOMIC);
 		if (hv_cpu->synic_event_page == NULL) {
 			pr_err("Unable to allocate SYNIC event page\n");
 			goto err;
 		}

 		hv_cpu->post_msg_page = (void *)get_zeroed_page(GFP_ATOMIC);
 		if (hv_cpu->post_msg_page == NULL) {
 			pr_err("Unable to allocate post msg page\n");
 			goto err;
 		}

 		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:
 	/*
 	 * Any memory allocations that succeeded will be freed when
 	 * the caller cleans up by calling hv_synic_free()
 	 */
 	return -ENOMEM;
 }


 void hv_synic_free(void)
 {
 	int cpu;

 	for_each_present_cpu(cpu) {
 		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);
 	}

 	kfree(hv_context.hv_numa_map);
 }

 /*
  * hv_synic_init - Initialize the Synthetic Interrupt Controller.
  *
  * If it is already initialized by another entity (ie x2v shim), we need to
  * retrieve the initialized message and event pages.  Otherwise, we create and
  * initialize the message and event pages.
  */
 int hv_synic_init(unsigned int cpu)
 {
 	struct hv_per_cpu_context *hv_cpu
 		= per_cpu_ptr(hv_context.cpu_context, cpu);
 	union hv_synic_simp simp;
 	union hv_synic_siefp siefp;
 	union hv_synic_sint shared_sint;
 	union hv_synic_scontrol sctrl;

 	/* Setup the Synic's message page */
 	hv_get_simp(simp.as_uint64);
 	simp.simp_enabled = 1;
 	simp.base_simp_gpa = virt_to_phys(hv_cpu->synic_message_page)
 		>> PAGE_SHIFT;

 	hv_set_simp(simp.as_uint64);

 	/* Setup the Synic's event page */
 	hv_get_siefp(siefp.as_uint64);
 	siefp.siefp_enabled = 1;
 	siefp.base_siefp_gpa = virt_to_phys(hv_cpu->synic_event_page)
 		>> PAGE_SHIFT;

 	hv_set_siefp(siefp.as_uint64);

 	/* Setup the shared SINT. */
 	hv_get_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

 	shared_sint.vector = HYPERVISOR_CALLBACK_VECTOR;
 	shared_sint.masked = false;
 	if (ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED)
 		shared_sint.auto_eoi = false;
 	else
 		shared_sint.auto_eoi = true;

 	hv_set_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

 	/* Enable the global synic bit */
 	hv_get_synic_state(sctrl.as_uint64);
 	sctrl.enable = 1;

 	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;

 	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);
 	}
 }

 /*
  * hv_synic_cleanup - Cleanup routine for hv_synic_init().
  */
 int hv_synic_cleanup(unsigned int cpu)
 {
 	union hv_synic_sint shared_sint;
 	union hv_synic_simp simp;
 	union hv_synic_siefp siefp;
 	union hv_synic_scontrol sctrl;
 	struct vmbus_channel *channel, *sc;
 	bool channel_found = false;
 	unsigned long flags;

 	hv_get_synic_state(sctrl.as_uint64);
 	if (sctrl.enable != 1)
 		return -EFAULT;

 	/*
 	 * Search for channels which are bound to the CPU we're about to
 	 * cleanup. In case we find one and vmbus is still connected we need to
 	 * fail, this will effectively prevent CPU offlining. There is no way
 	 * we can re-bind channels to different CPUs for now.
 	 */
 	mutex_lock(&vmbus_connection.channel_mutex);
 	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 		if (channel->target_cpu == cpu) {
 			channel_found = true;
 			break;
 		}
 		spin_lock_irqsave(&channel->lock, flags);
 		list_for_each_entry(sc, &channel->sc_list, sc_list) {
 			if (sc->target_cpu == cpu) {
 				channel_found = true;
 				break;
 			}
 		}
 		spin_unlock_irqrestore(&channel->lock, flags);
 		if (channel_found)
 			break;
 	}
 	mutex_unlock(&vmbus_connection.channel_mutex);

 	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_get_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

 	shared_sint.masked = 1;

 	/* Need to correctly cleanup in the case of SMP!!! */
 	/* Disable the interrupt */
 	hv_set_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

 	hv_get_simp(simp.as_uint64);
 	simp.simp_enabled = 0;
 	simp.base_simp_gpa = 0;

 	hv_set_simp(simp.as_uint64);

 	hv_get_siefp(siefp.as_uint64);
 	siefp.siefp_enabled = 0;
 	siefp.base_siefp_gpa = 0;

 	hv_set_siefp(siefp.as_uint64);

 	/* Disable the global synic bit */
 	sctrl.enable = 0;
 	hv_set_synic_state(sctrl.as_uint64);

 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (c) 2009, Microsoft Corporation.
	*
	* Authors:
	* Haiyang Zhang <haiyangz@microsoft.com>
	* Hank Janssen <hjanssen@microsoft.com>
	*/
	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/slab.h>
	#include <linux/vmalloc.h>
	#include <linux/hyperv.h>
	#include <linux/version.h>
	#include <linux/random.h>
	#include <linux/clockchips.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.
	*
	* This routine must be called before any other routines in here are called
	*/
	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;
	}

	/*
	* hv_post_message - Post a message using the hypervisor message IPC.
	*
	* This involves a hypercall.
	*/
	int hv_post_message(union hv_connection_id connection_id,
	enum hv_message_type message_type,
	void *payload, size_t payload_size)
	{
	struct hv_input_post_message *aligned_msg;
	struct hv_per_cpu_context *hv_cpu;
	u64 status;

	if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
	return -EMSGSIZE;

	hv_cpu = get_cpu_ptr(hv_context.cpu_context);
	aligned_msg = hv_cpu->post_msg_page;
	aligned_msg->connectionid = connection_id;
	aligned_msg->reserved = 0;
	aligned_msg->message_type = message_type;
	aligned_msg->payload_size = payload_size;
	memcpy((void *)aligned_msg->payload, payload, payload_size);

	status = hv_do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL);

	/* Preemption must remain disabled until after the hypercall
	* so some other thread can't get scheduled onto this cpu and
	* corrupt the per-cpu post_msg_page
	*/
	put_cpu_ptr(hv_cpu);

	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;
	struct hv_per_cpu_context *hv_cpu;

	/*
	* First, zero all per-cpu memory areas so hv_synic_free() can
	* detect what memory has been allocated and cleanup properly
	* after any failures.
	*/
	for_each_present_cpu(cpu) {
	hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu);
	memset(hv_cpu, 0, sizeof(*hv_cpu));
	}

	hv_context.hv_numa_map = kcalloc(nr_node_ids, sizeof(struct cpumask),
	GFP_KERNEL);
	if (hv_context.hv_numa_map == NULL) {
	pr_err("Unable to allocate NUMA map\n");
	goto err;
	}

	for_each_present_cpu(cpu) {
	hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu);

	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) {
	pr_err("Unable to allocate SYNIC message page\n");
	goto err;
	}

	hv_cpu->synic_event_page = (void *)get_zeroed_page(GFP_ATOMIC);
	if (hv_cpu->synic_event_page == NULL) {
	pr_err("Unable to allocate SYNIC event page\n");
	goto err;
	}

	hv_cpu->post_msg_page = (void *)get_zeroed_page(GFP_ATOMIC);
	if (hv_cpu->post_msg_page == NULL) {
	pr_err("Unable to allocate post msg page\n");
	goto err;
	}

	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:
	/*
	* Any memory allocations that succeeded will be freed when
	* the caller cleans up by calling hv_synic_free()
	*/
	return -ENOMEM;
	}


	void hv_synic_free(void)
	{
	int cpu;

	for_each_present_cpu(cpu) {
	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);
	}

	kfree(hv_context.hv_numa_map);
	}

	/*
	* hv_synic_init - Initialize the Synthetic Interrupt Controller.
	*
	* If it is already initialized by another entity (ie x2v shim), we need to
	* retrieve the initialized message and event pages. Otherwise, we create and
	* initialize the message and event pages.
	*/
	int hv_synic_init(unsigned int cpu)
	{
	struct hv_per_cpu_context *hv_cpu
	= per_cpu_ptr(hv_context.cpu_context, cpu);
	union hv_synic_simp simp;
	union hv_synic_siefp siefp;
	union hv_synic_sint shared_sint;
	union hv_synic_scontrol sctrl;

	/* Setup the Synic's message page */
	hv_get_simp(simp.as_uint64);
	simp.simp_enabled = 1;
	simp.base_simp_gpa = virt_to_phys(hv_cpu->synic_message_page)
	>> PAGE_SHIFT;

	hv_set_simp(simp.as_uint64);

	/* Setup the Synic's event page */
	hv_get_siefp(siefp.as_uint64);
	siefp.siefp_enabled = 1;
	siefp.base_siefp_gpa = virt_to_phys(hv_cpu->synic_event_page)
	>> PAGE_SHIFT;

	hv_set_siefp(siefp.as_uint64);

	/* Setup the shared SINT. */
	hv_get_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

	shared_sint.vector = HYPERVISOR_CALLBACK_VECTOR;
	shared_sint.masked = false;
	if (ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED)
	shared_sint.auto_eoi = false;
	else
	shared_sint.auto_eoi = true;

	hv_set_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

	/* Enable the global synic bit */
	hv_get_synic_state(sctrl.as_uint64);
	sctrl.enable = 1;

	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;

	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);
	}
	}

	/*
	* hv_synic_cleanup - Cleanup routine for hv_synic_init().
	*/
	int hv_synic_cleanup(unsigned int cpu)
	{
	union hv_synic_sint shared_sint;
	union hv_synic_simp simp;
	union hv_synic_siefp siefp;
	union hv_synic_scontrol sctrl;
	struct vmbus_channel channel, sc;
	bool channel_found = false;
	unsigned long flags;

	hv_get_synic_state(sctrl.as_uint64);
	if (sctrl.enable != 1)
	return -EFAULT;

	/*
	* Search for channels which are bound to the CPU we're about to
	* cleanup. In case we find one and vmbus is still connected we need to
	* fail, this will effectively prevent CPU offlining. There is no way
	* we can re-bind channels to different CPUs for now.
	*/
	mutex_lock(&vmbus_connection.channel_mutex);
	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
	if (channel->target_cpu == cpu) {
	channel_found = true;
	break;
	}
	spin_lock_irqsave(&channel->lock, flags);
	list_for_each_entry(sc, &channel->sc_list, sc_list) {
	if (sc->target_cpu == cpu) {
	channel_found = true;
	break;
	}
	}
	spin_unlock_irqrestore(&channel->lock, flags);
	if (channel_found)
	break;
	}
	mutex_unlock(&vmbus_connection.channel_mutex);

	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_get_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

	shared_sint.masked = 1;

	/* Need to correctly cleanup in the case of SMP!!! */
	/* Disable the interrupt */
	hv_set_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

	hv_get_simp(simp.as_uint64);
	simp.simp_enabled = 0;
	simp.base_simp_gpa = 0;

	hv_set_simp(simp.as_uint64);

	hv_get_siefp(siefp.as_uint64);
	siefp.siefp_enabled = 0;
	siefp.base_siefp_gpa = 0;

	hv_set_siefp(siefp.as_uint64);

	/* Disable the global synic bit */
	sctrl.enable = 0;
	hv_set_synic_state(sctrl.as_uint64);

	return 0;
	}