// SPDX-License-Identifier: GPL-2.0-only

  /*

   * Copyright (c) 2009, Microsoft Corporation.
   *

   * Authors:
   *   Haiyang Zhang <haiyangz@microsoft.com>
   *   Hank Janssen  <hjanssen@microsoft.com>

   *   K. Y. Srinivasan <kys@microsoft.com>

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/device.h>

  #include <linux/interrupt.h>
  #include <linux/sysctl.h>

  #include <linux/slab.h>

  #include <linux/acpi.h>

  #include <linux/completion.h>

  #include <linux/hyperv.h>

  #include <linux/kernel_stat.h>

  #include <linux/clockchips.h>

  #include <linux/cpu.h>

  #include <linux/sched/task_stack.h>

  #include <asm/mshyperv.h>

  #include <linux/delay.h>

  #include <linux/notifier.h>
  #include <linux/ptrace.h>

  #include <linux/screen_info.h>

  #include <linux/kdebug.h>

  #include <linux/efi.h>

  #include <linux/random.h>

  #include <linux/syscore_ops.h>

  #include <clocksource/hyperv_timer.h>

  #include "hyperv_vmbus.h"

  struct vmbus_dynid {
  	struct list_head node;
  	struct hv_vmbus_device_id id;
  };

  static struct acpi_device  *hv_acpi_dev;

  static struct completion probe_event;

  static int hyperv_cpuhp_online;

  static void *hv_panic_page;

  static int hyperv_panic_event(struct notifier_block *nb, unsigned long val,
  			      void *args)
  {
  	struct pt_regs *regs;
  
  	regs = current_pt_regs();

  	hyperv_report_panic(regs, val);

  	return NOTIFY_DONE;
  }

  static int hyperv_die_event(struct notifier_block *nb, unsigned long val,
  			    void *args)
  {
  	struct die_args *die = (struct die_args *)args;
  	struct pt_regs *regs = die->regs;

  	hyperv_report_panic(regs, val);

  	return NOTIFY_DONE;
  }
  
  static struct notifier_block hyperv_die_block = {
  	.notifier_call = hyperv_die_event,
  };

  static struct notifier_block hyperv_panic_block = {
  	.notifier_call = hyperv_panic_event,
  };

  static const char *fb_mmio_name = "fb_range";
  static struct resource *fb_mmio;

  static struct resource *hyperv_mmio;
  static DEFINE_SEMAPHORE(hyperv_mmio_lock);

  static int vmbus_exists(void)
  {
  	if (hv_acpi_dev == NULL)
  		return -ENODEV;
  
  	return 0;
  }

  #define VMBUS_ALIAS_LEN ((sizeof((struct hv_vmbus_device_id *)0)->guid) * 2)
  static void print_alias_name(struct hv_device *hv_dev, char *alias_name)
  {
  	int i;
  	for (i = 0; i < VMBUS_ALIAS_LEN; i += 2)
  		sprintf(&alias_name[i], "%02x", hv_dev->dev_type.b[i/2]);
  }

  static u8 channel_monitor_group(const struct vmbus_channel *channel)

  {
  	return (u8)channel->offermsg.monitorid / 32;
  }

  static u8 channel_monitor_offset(const struct vmbus_channel *channel)

  {
  	return (u8)channel->offermsg.monitorid % 32;
  }

  static u32 channel_pending(const struct vmbus_channel *channel,
  			   const struct hv_monitor_page *monitor_page)

  {
  	u8 monitor_group = channel_monitor_group(channel);

  	return monitor_page->trigger_group[monitor_group].pending;
  }

  static u32 channel_latency(const struct vmbus_channel *channel,
  			   const struct hv_monitor_page *monitor_page)

  {
  	u8 monitor_group = channel_monitor_group(channel);
  	u8 monitor_offset = channel_monitor_offset(channel);

  	return monitor_page->latency[monitor_group][monitor_offset];
  }

  static u32 channel_conn_id(struct vmbus_channel *channel,
  			   struct hv_monitor_page *monitor_page)
  {
  	u8 monitor_group = channel_monitor_group(channel);
  	u8 monitor_offset = channel_monitor_offset(channel);
  	return monitor_page->parameter[monitor_group][monitor_offset].connectionid.u.id;
  }

  static ssize_t id_show(struct device *dev, struct device_attribute *dev_attr,
  		       char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  	return sprintf(buf, "%d
  ", hv_dev->channel->offermsg.child_relid);
  }
  static DEVICE_ATTR_RO(id);

  static ssize_t state_show(struct device *dev, struct device_attribute *dev_attr,
  			  char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  	return sprintf(buf, "%d
  ", hv_dev->channel->state);
  }
  static DEVICE_ATTR_RO(state);

  static ssize_t monitor_id_show(struct device *dev,
  			       struct device_attribute *dev_attr, char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  	return sprintf(buf, "%d
  ", hv_dev->channel->offermsg.monitorid);
  }
  static DEVICE_ATTR_RO(monitor_id);

  static ssize_t class_id_show(struct device *dev,
  			       struct device_attribute *dev_attr, char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  	return sprintf(buf, "{%pUl}
  ",
  		       hv_dev->channel->offermsg.offer.if_type.b);
  }
  static DEVICE_ATTR_RO(class_id);

  static ssize_t device_id_show(struct device *dev,
  			      struct device_attribute *dev_attr, char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  	return sprintf(buf, "{%pUl}
  ",
  		       hv_dev->channel->offermsg.offer.if_instance.b);
  }
  static DEVICE_ATTR_RO(device_id);

  static ssize_t modalias_show(struct device *dev,
  			     struct device_attribute *dev_attr, char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	char alias_name[VMBUS_ALIAS_LEN + 1];
  
  	print_alias_name(hv_dev, alias_name);
  	return sprintf(buf, "vmbus:%s
  ", alias_name);
  }
  static DEVICE_ATTR_RO(modalias);

  #ifdef CONFIG_NUMA
  static ssize_t numa_node_show(struct device *dev,
  			      struct device_attribute *attr, char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  
  	return sprintf(buf, "%d
  ", hv_dev->channel->numa_node);
  }
  static DEVICE_ATTR_RO(numa_node);
  #endif

  static ssize_t server_monitor_pending_show(struct device *dev,
  					   struct device_attribute *dev_attr,
  					   char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  	return sprintf(buf, "%d
  ",
  		       channel_pending(hv_dev->channel,

  				       vmbus_connection.monitor_pages[0]));

  }
  static DEVICE_ATTR_RO(server_monitor_pending);
  
  static ssize_t client_monitor_pending_show(struct device *dev,
  					   struct device_attribute *dev_attr,
  					   char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  	return sprintf(buf, "%d
  ",
  		       channel_pending(hv_dev->channel,
  				       vmbus_connection.monitor_pages[1]));
  }
  static DEVICE_ATTR_RO(client_monitor_pending);

  static ssize_t server_monitor_latency_show(struct device *dev,
  					   struct device_attribute *dev_attr,
  					   char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  	return sprintf(buf, "%d
  ",
  		       channel_latency(hv_dev->channel,
  				       vmbus_connection.monitor_pages[0]));
  }
  static DEVICE_ATTR_RO(server_monitor_latency);
  
  static ssize_t client_monitor_latency_show(struct device *dev,
  					   struct device_attribute *dev_attr,
  					   char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  	return sprintf(buf, "%d
  ",
  		       channel_latency(hv_dev->channel,
  				       vmbus_connection.monitor_pages[1]));
  }
  static DEVICE_ATTR_RO(client_monitor_latency);

  static ssize_t server_monitor_conn_id_show(struct device *dev,
  					   struct device_attribute *dev_attr,
  					   char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  	return sprintf(buf, "%d
  ",
  		       channel_conn_id(hv_dev->channel,
  				       vmbus_connection.monitor_pages[0]));
  }
  static DEVICE_ATTR_RO(server_monitor_conn_id);
  
  static ssize_t client_monitor_conn_id_show(struct device *dev,
  					   struct device_attribute *dev_attr,
  					   char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	if (!hv_dev->channel)
  		return -ENODEV;
  	return sprintf(buf, "%d
  ",
  		       channel_conn_id(hv_dev->channel,
  				       vmbus_connection.monitor_pages[1]));
  }
  static DEVICE_ATTR_RO(client_monitor_conn_id);

  static ssize_t out_intr_mask_show(struct device *dev,
  				  struct device_attribute *dev_attr, char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	struct hv_ring_buffer_debug_info outbound;

  	int ret;

  
  	if (!hv_dev->channel)
  		return -ENODEV;

  
  	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
  					  &outbound);
  	if (ret < 0)
  		return ret;

  	return sprintf(buf, "%d
  ", outbound.current_interrupt_mask);
  }
  static DEVICE_ATTR_RO(out_intr_mask);
  
  static ssize_t out_read_index_show(struct device *dev,
  				   struct device_attribute *dev_attr, char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	struct hv_ring_buffer_debug_info outbound;

  	int ret;

  
  	if (!hv_dev->channel)
  		return -ENODEV;

  
  	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
  					  &outbound);
  	if (ret < 0)
  		return ret;

  	return sprintf(buf, "%d
  ", outbound.current_read_index);
  }
  static DEVICE_ATTR_RO(out_read_index);
  
  static ssize_t out_write_index_show(struct device *dev,
  				    struct device_attribute *dev_attr,
  				    char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	struct hv_ring_buffer_debug_info outbound;

  	int ret;

  
  	if (!hv_dev->channel)
  		return -ENODEV;

  
  	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
  					  &outbound);
  	if (ret < 0)
  		return ret;

  	return sprintf(buf, "%d
  ", outbound.current_write_index);
  }
  static DEVICE_ATTR_RO(out_write_index);
  
  static ssize_t out_read_bytes_avail_show(struct device *dev,
  					 struct device_attribute *dev_attr,
  					 char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	struct hv_ring_buffer_debug_info outbound;

  	int ret;

  
  	if (!hv_dev->channel)
  		return -ENODEV;

  
  	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
  					  &outbound);
  	if (ret < 0)
  		return ret;

  	return sprintf(buf, "%d
  ", outbound.bytes_avail_toread);
  }
  static DEVICE_ATTR_RO(out_read_bytes_avail);
  
  static ssize_t out_write_bytes_avail_show(struct device *dev,
  					  struct device_attribute *dev_attr,
  					  char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	struct hv_ring_buffer_debug_info outbound;

  	int ret;

  
  	if (!hv_dev->channel)
  		return -ENODEV;

  
  	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
  					  &outbound);
  	if (ret < 0)
  		return ret;

  	return sprintf(buf, "%d
  ", outbound.bytes_avail_towrite);
  }
  static DEVICE_ATTR_RO(out_write_bytes_avail);
  
  static ssize_t in_intr_mask_show(struct device *dev,
  				 struct device_attribute *dev_attr, char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	struct hv_ring_buffer_debug_info inbound;

  	int ret;

  
  	if (!hv_dev->channel)
  		return -ENODEV;

  
  	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
  	if (ret < 0)
  		return ret;

  	return sprintf(buf, "%d
  ", inbound.current_interrupt_mask);
  }
  static DEVICE_ATTR_RO(in_intr_mask);
  
  static ssize_t in_read_index_show(struct device *dev,
  				  struct device_attribute *dev_attr, char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	struct hv_ring_buffer_debug_info inbound;

  	int ret;

  
  	if (!hv_dev->channel)
  		return -ENODEV;

  
  	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
  	if (ret < 0)
  		return ret;

  	return sprintf(buf, "%d
  ", inbound.current_read_index);
  }
  static DEVICE_ATTR_RO(in_read_index);
  
  static ssize_t in_write_index_show(struct device *dev,
  				   struct device_attribute *dev_attr, char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	struct hv_ring_buffer_debug_info inbound;

  	int ret;

  
  	if (!hv_dev->channel)
  		return -ENODEV;

  
  	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
  	if (ret < 0)
  		return ret;

  	return sprintf(buf, "%d
  ", inbound.current_write_index);
  }
  static DEVICE_ATTR_RO(in_write_index);
  
  static ssize_t in_read_bytes_avail_show(struct device *dev,
  					struct device_attribute *dev_attr,
  					char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	struct hv_ring_buffer_debug_info inbound;

  	int ret;

  
  	if (!hv_dev->channel)
  		return -ENODEV;

  
  	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
  	if (ret < 0)
  		return ret;

  	return sprintf(buf, "%d
  ", inbound.bytes_avail_toread);
  }
  static DEVICE_ATTR_RO(in_read_bytes_avail);
  
  static ssize_t in_write_bytes_avail_show(struct device *dev,
  					 struct device_attribute *dev_attr,
  					 char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	struct hv_ring_buffer_debug_info inbound;

  	int ret;

  
  	if (!hv_dev->channel)
  		return -ENODEV;

  
  	ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
  	if (ret < 0)
  		return ret;

  	return sprintf(buf, "%d
  ", inbound.bytes_avail_towrite);
  }
  static DEVICE_ATTR_RO(in_write_bytes_avail);

  static ssize_t channel_vp_mapping_show(struct device *dev,
  				       struct device_attribute *dev_attr,
  				       char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	struct vmbus_channel *channel = hv_dev->channel, *cur_sc;
  	unsigned long flags;
  	int buf_size = PAGE_SIZE, n_written, tot_written;
  	struct list_head *cur;
  
  	if (!channel)
  		return -ENODEV;
  
  	tot_written = snprintf(buf, buf_size, "%u:%u
  ",
  		channel->offermsg.child_relid, channel->target_cpu);
  
  	spin_lock_irqsave(&channel->lock, flags);
  
  	list_for_each(cur, &channel->sc_list) {
  		if (tot_written >= buf_size - 1)
  			break;
  
  		cur_sc = list_entry(cur, struct vmbus_channel, sc_list);
  		n_written = scnprintf(buf + tot_written,
  				     buf_size - tot_written,
  				     "%u:%u
  ",
  				     cur_sc->offermsg.child_relid,
  				     cur_sc->target_cpu);
  		tot_written += n_written;
  	}
  
  	spin_unlock_irqrestore(&channel->lock, flags);
  
  	return tot_written;
  }
  static DEVICE_ATTR_RO(channel_vp_mapping);

  static ssize_t vendor_show(struct device *dev,
  			   struct device_attribute *dev_attr,
  			   char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	return sprintf(buf, "0x%x
  ", hv_dev->vendor_id);
  }
  static DEVICE_ATTR_RO(vendor);
  
  static ssize_t device_show(struct device *dev,
  			   struct device_attribute *dev_attr,
  			   char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	return sprintf(buf, "0x%x
  ", hv_dev->device_id);
  }
  static DEVICE_ATTR_RO(device);

  static ssize_t driver_override_store(struct device *dev,
  				     struct device_attribute *attr,
  				     const char *buf, size_t count)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	char *driver_override, *old, *cp;
  
  	/* We need to keep extra room for a newline */
  	if (count >= (PAGE_SIZE - 1))
  		return -EINVAL;
  
  	driver_override = kstrndup(buf, count, GFP_KERNEL);
  	if (!driver_override)
  		return -ENOMEM;
  
  	cp = strchr(driver_override, '
  ');
  	if (cp)
  		*cp = '\0';
  
  	device_lock(dev);
  	old = hv_dev->driver_override;
  	if (strlen(driver_override)) {
  		hv_dev->driver_override = driver_override;
  	} else {
  		kfree(driver_override);
  		hv_dev->driver_override = NULL;
  	}
  	device_unlock(dev);
  
  	kfree(old);
  
  	return count;
  }
  
  static ssize_t driver_override_show(struct device *dev,
  				    struct device_attribute *attr, char *buf)
  {
  	struct hv_device *hv_dev = device_to_hv_device(dev);
  	ssize_t len;
  
  	device_lock(dev);
  	len = snprintf(buf, PAGE_SIZE, "%s
  ", hv_dev->driver_override);
  	device_unlock(dev);
  
  	return len;
  }
  static DEVICE_ATTR_RW(driver_override);

  /* Set up per device attributes in /sys/bus/vmbus/devices/<bus device> */

  static struct attribute *vmbus_dev_attrs[] = {

  	&dev_attr_id.attr,

  	&dev_attr_state.attr,

  	&dev_attr_monitor_id.attr,

  	&dev_attr_class_id.attr,

  	&dev_attr_device_id.attr,

  	&dev_attr_modalias.attr,

  #ifdef CONFIG_NUMA
  	&dev_attr_numa_node.attr,
  #endif

  	&dev_attr_server_monitor_pending.attr,
  	&dev_attr_client_monitor_pending.attr,

  	&dev_attr_server_monitor_latency.attr,
  	&dev_attr_client_monitor_latency.attr,

  	&dev_attr_server_monitor_conn_id.attr,
  	&dev_attr_client_monitor_conn_id.attr,

  	&dev_attr_out_intr_mask.attr,
  	&dev_attr_out_read_index.attr,
  	&dev_attr_out_write_index.attr,
  	&dev_attr_out_read_bytes_avail.attr,
  	&dev_attr_out_write_bytes_avail.attr,
  	&dev_attr_in_intr_mask.attr,
  	&dev_attr_in_read_index.attr,
  	&dev_attr_in_write_index.attr,
  	&dev_attr_in_read_bytes_avail.attr,
  	&dev_attr_in_write_bytes_avail.attr,

  	&dev_attr_channel_vp_mapping.attr,

  	&dev_attr_vendor.attr,
  	&dev_attr_device.attr,

  	&dev_attr_driver_override.attr,

  	NULL,
  };

  
  /*
   * Device-level attribute_group callback function. Returns the permission for
   * each attribute, and returns 0 if an attribute is not visible.
   */
  static umode_t vmbus_dev_attr_is_visible(struct kobject *kobj,
  					 struct attribute *attr, int idx)
  {
  	struct device *dev = kobj_to_dev(kobj);
  	const struct hv_device *hv_dev = device_to_hv_device(dev);
  
  	/* Hide the monitor attributes if the monitor mechanism is not used. */
  	if (!hv_dev->channel->offermsg.monitor_allocated &&
  	    (attr == &dev_attr_monitor_id.attr ||
  	     attr == &dev_attr_server_monitor_pending.attr ||
  	     attr == &dev_attr_client_monitor_pending.attr ||
  	     attr == &dev_attr_server_monitor_latency.attr ||
  	     attr == &dev_attr_client_monitor_latency.attr ||
  	     attr == &dev_attr_server_monitor_conn_id.attr ||
  	     attr == &dev_attr_client_monitor_conn_id.attr))
  		return 0;
  
  	return attr->mode;
  }
  
  static const struct attribute_group vmbus_dev_group = {
  	.attrs = vmbus_dev_attrs,
  	.is_visible = vmbus_dev_attr_is_visible
  };
  __ATTRIBUTE_GROUPS(vmbus_dev);

  /*
   * vmbus_uevent - add uevent for our device
   *
   * This routine is invoked when a device is added or removed on the vmbus to
   * generate a uevent to udev in the userspace. The udev will then look at its
   * rule and the uevent generated here to load the appropriate driver

   *
   * The alias string will be of the form vmbus:guid where guid is the string
   * representation of the device guid (each byte of the guid will be
   * represented with two hex characters.

   */
  static int vmbus_uevent(struct device *device, struct kobj_uevent_env *env)
  {
  	struct hv_device *dev = device_to_hv_device(device);

  	int ret;
  	char alias_name[VMBUS_ALIAS_LEN + 1];

  	print_alias_name(dev, alias_name);

  	ret = add_uevent_var(env, "MODALIAS=vmbus:%s", alias_name);
  	return ret;

  }

  static const struct hv_vmbus_device_id *

  hv_vmbus_dev_match(const struct hv_vmbus_device_id *id, const guid_t *guid)

  {
  	if (id == NULL)
  		return NULL; /* empty device table */

  	for (; !guid_is_null(&id->guid); id++)
  		if (guid_equal(&id->guid, guid))

  			return id;
  
  	return NULL;
  }
  
  static const struct hv_vmbus_device_id *

  hv_vmbus_dynid_match(struct hv_driver *drv, const guid_t *guid)

  {

  	const struct hv_vmbus_device_id *id = NULL;
  	struct vmbus_dynid *dynid;

  	spin_lock(&drv->dynids.lock);
  	list_for_each_entry(dynid, &drv->dynids.list, node) {

  		if (guid_equal(&dynid->id.guid, guid)) {

  			id = &dynid->id;
  			break;
  		}
  	}
  	spin_unlock(&drv->dynids.lock);

  	return id;
  }

  static const struct hv_vmbus_device_id vmbus_device_null;

  /*
   * Return a matching hv_vmbus_device_id pointer.
   * If there is no match, return NULL.
   */
  static const struct hv_vmbus_device_id *hv_vmbus_get_id(struct hv_driver *drv,
  							struct hv_device *dev)
  {

  	const guid_t *guid = &dev->dev_type;

  	const struct hv_vmbus_device_id *id;

  	/* When driver_override is set, only bind to the matching driver */
  	if (dev->driver_override && strcmp(dev->driver_override, drv->name))
  		return NULL;
  
  	/* Look at the dynamic ids first, before the static ones */
  	id = hv_vmbus_dynid_match(drv, guid);
  	if (!id)
  		id = hv_vmbus_dev_match(drv->id_table, guid);
  
  	/* driver_override will always match, send a dummy id */
  	if (!id && dev->driver_override)
  		id = &vmbus_device_null;
  
  	return id;

  }

  /* vmbus_add_dynid - add a new device ID to this driver and re-probe devices */

  static int vmbus_add_dynid(struct hv_driver *drv, guid_t *guid)

  {
  	struct vmbus_dynid *dynid;
  
  	dynid = kzalloc(sizeof(*dynid), GFP_KERNEL);
  	if (!dynid)
  		return -ENOMEM;
  
  	dynid->id.guid = *guid;
  
  	spin_lock(&drv->dynids.lock);
  	list_add_tail(&dynid->node, &drv->dynids.list);
  	spin_unlock(&drv->dynids.lock);
  
  	return driver_attach(&drv->driver);
  }
  
  static void vmbus_free_dynids(struct hv_driver *drv)
  {
  	struct vmbus_dynid *dynid, *n;
  
  	spin_lock(&drv->dynids.lock);
  	list_for_each_entry_safe(dynid, n, &drv->dynids.list, node) {
  		list_del(&dynid->node);
  		kfree(dynid);
  	}
  	spin_unlock(&drv->dynids.lock);
  }

  /*
   * store_new_id - sysfs frontend to vmbus_add_dynid()
   *
   * Allow GUIDs to be added to an existing driver via sysfs.
   */
  static ssize_t new_id_store(struct device_driver *driver, const char *buf,
  			    size_t count)
  {
  	struct hv_driver *drv = drv_to_hv_drv(driver);

  	guid_t guid;

  	ssize_t retval;

  	retval = guid_parse(buf, &guid);

  	if (retval)
  		return retval;

  	if (hv_vmbus_dynid_match(drv, &guid))

  		return -EEXIST;
  
  	retval = vmbus_add_dynid(drv, &guid);
  	if (retval)
  		return retval;
  	return count;
  }
  static DRIVER_ATTR_WO(new_id);
  
  /*
   * store_remove_id - remove a PCI device ID from this driver
   *
   * Removes a dynamic pci device ID to this driver.
   */
  static ssize_t remove_id_store(struct device_driver *driver, const char *buf,
  			       size_t count)
  {
  	struct hv_driver *drv = drv_to_hv_drv(driver);
  	struct vmbus_dynid *dynid, *n;

  	guid_t guid;

  	ssize_t retval;

  	retval = guid_parse(buf, &guid);

  	if (retval)
  		return retval;

  	retval = -ENODEV;

  	spin_lock(&drv->dynids.lock);
  	list_for_each_entry_safe(dynid, n, &drv->dynids.list, node) {
  		struct hv_vmbus_device_id *id = &dynid->id;

  		if (guid_equal(&id->guid, &guid)) {

  			list_del(&dynid->node);
  			kfree(dynid);
  			retval = count;
  			break;
  		}
  	}
  	spin_unlock(&drv->dynids.lock);
  
  	return retval;
  }
  static DRIVER_ATTR_WO(remove_id);
  
  static struct attribute *vmbus_drv_attrs[] = {
  	&driver_attr_new_id.attr,
  	&driver_attr_remove_id.attr,
  	NULL,
  };
  ATTRIBUTE_GROUPS(vmbus_drv);

  
  /*
   * vmbus_match - Attempt to match the specified device to the specified driver
   */
  static int vmbus_match(struct device *device, struct device_driver *driver)
  {

  	struct hv_driver *drv = drv_to_hv_drv(driver);

  	struct hv_device *hv_dev = device_to_hv_device(device);

  	/* The hv_sock driver handles all hv_sock offers. */
  	if (is_hvsock_channel(hv_dev->channel))
  		return drv->hvsock;

  	if (hv_vmbus_get_id(drv, hv_dev))

  		return 1;

  	return 0;

  }

  /*
   * vmbus_probe - Add the new vmbus's child device
   */
  static int vmbus_probe(struct device *child_device)
  {
  	int ret = 0;
  	struct hv_driver *drv =
  			drv_to_hv_drv(child_device->driver);

  	struct hv_device *dev = device_to_hv_device(child_device);

  	const struct hv_vmbus_device_id *dev_id;

  	dev_id = hv_vmbus_get_id(drv, dev);

  	if (drv->probe) {

  		ret = drv->probe(dev, dev_id);

  		if (ret != 0)

  			pr_err("probe failed for device %s (%d)
  ",
  			       dev_name(child_device), ret);

  	} else {

  		pr_err("probe not set for driver %s
  ",
  		       dev_name(child_device));

  		ret = -ENODEV;

  	}
  	return ret;
  }

  /*
   * vmbus_remove - Remove a vmbus device
   */
  static int vmbus_remove(struct device *child_device)
  {

  	struct hv_driver *drv;

  	struct hv_device *dev = device_to_hv_device(child_device);

  	if (child_device->driver) {
  		drv = drv_to_hv_drv(child_device->driver);
  		if (drv->remove)
  			drv->remove(dev);

  	}

  
  	return 0;
  }

  
  /*
   * vmbus_shutdown - Shutdown a vmbus device
   */
  static void vmbus_shutdown(struct device *child_device)
  {
  	struct hv_driver *drv;

  	struct hv_device *dev = device_to_hv_device(child_device);

  
  
  	/* The device may not be attached yet */
  	if (!child_device->driver)
  		return;
  
  	drv = drv_to_hv_drv(child_device->driver);

  	if (drv->shutdown)
  		drv->shutdown(dev);

  }

  #ifdef CONFIG_PM_SLEEP

  /*
   * vmbus_suspend - Suspend a vmbus device
   */
  static int vmbus_suspend(struct device *child_device)
  {
  	struct hv_driver *drv;
  	struct hv_device *dev = device_to_hv_device(child_device);
  
  	/* The device may not be attached yet */
  	if (!child_device->driver)
  		return 0;
  
  	drv = drv_to_hv_drv(child_device->driver);
  	if (!drv->suspend)
  		return -EOPNOTSUPP;
  
  	return drv->suspend(dev);
  }
  
  /*
   * vmbus_resume - Resume a vmbus device
   */
  static int vmbus_resume(struct device *child_device)
  {
  	struct hv_driver *drv;
  	struct hv_device *dev = device_to_hv_device(child_device);
  
  	/* The device may not be attached yet */
  	if (!child_device->driver)
  		return 0;
  
  	drv = drv_to_hv_drv(child_device->driver);
  	if (!drv->resume)
  		return -EOPNOTSUPP;
  
  	return drv->resume(dev);
  }

  #endif /* CONFIG_PM_SLEEP */

  
  /*
   * vmbus_device_release - Final callback release of the vmbus child device
   */
  static void vmbus_device_release(struct device *device)
  {

  	struct hv_device *hv_dev = device_to_hv_device(device);

  	struct vmbus_channel *channel = hv_dev->channel;

  	mutex_lock(&vmbus_connection.channel_mutex);

  	hv_process_channel_removal(channel);

  	mutex_unlock(&vmbus_connection.channel_mutex);

  	kfree(hv_dev);

  }

  /*
   * Note: we must use SET_NOIRQ_SYSTEM_SLEEP_PM_OPS rather than
   * SET_SYSTEM_SLEEP_PM_OPS: see the comment before vmbus_bus_pm.
   */
  static const struct dev_pm_ops vmbus_pm = {
  	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(vmbus_suspend, vmbus_resume)
  };

  /* The one and only one */

  static struct bus_type  hv_bus = {
  	.name =		"vmbus",
  	.match =		vmbus_match,
  	.shutdown =		vmbus_shutdown,
  	.remove =		vmbus_remove,
  	.probe =		vmbus_probe,
  	.uevent =		vmbus_uevent,

  	.dev_groups =		vmbus_dev_groups,
  	.drv_groups =		vmbus_drv_groups,

  	.pm =			&vmbus_pm,

  };

  struct onmessage_work_context {
  	struct work_struct work;
  	struct hv_message msg;
  };
  
  static void vmbus_onmessage_work(struct work_struct *work)
  {
  	struct onmessage_work_context *ctx;

  	/* Do not process messages if we're in DISCONNECTED state */
  	if (vmbus_connection.conn_state == DISCONNECTED)
  		return;

  	ctx = container_of(work, struct onmessage_work_context,
  			   work);
  	vmbus_onmessage(&ctx->msg);
  	kfree(ctx);
  }

  void vmbus_on_msg_dpc(unsigned long data)

  {

  	struct hv_per_cpu_context *hv_cpu = (void *)data;
  	void *page_addr = hv_cpu->synic_message_page;

  	struct hv_message *msg = (struct hv_message *)page_addr +
  				  VMBUS_MESSAGE_SINT;

  	struct vmbus_channel_message_header *hdr;

  	const struct vmbus_channel_message_table_entry *entry;

  	struct onmessage_work_context *ctx;

  	u32 message_type = msg->header.message_type;

  	if (message_type == HVMSG_NONE)

  		/* no msg */
  		return;

  	hdr = (struct vmbus_channel_message_header *)msg->u.payload;

  	trace_vmbus_on_msg_dpc(hdr);

  	if (hdr->msgtype >= CHANNELMSG_COUNT) {
  		WARN_ONCE(1, "unknown msgtype=%d
  ", hdr->msgtype);
  		goto msg_handled;
  	}

  	entry = &channel_message_table[hdr->msgtype];
  	if (entry->handler_type	== VMHT_BLOCKING) {
  		ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
  		if (ctx == NULL)
  			return;

  		INIT_WORK(&ctx->work, vmbus_onmessage_work);
  		memcpy(&ctx->msg, msg, sizeof(*msg));

  		/*
  		 * The host can generate a rescind message while we
  		 * may still be handling the original offer. We deal with
  		 * this condition by ensuring the processing is done on the
  		 * same CPU.
  		 */
  		switch (hdr->msgtype) {
  		case CHANNELMSG_RESCIND_CHANNELOFFER:
  			/*
  			 * If we are handling the rescind message;
  			 * schedule the work on the global work queue.
  			 */
  			schedule_work_on(vmbus_connection.connect_cpu,
  					 &ctx->work);
  			break;
  
  		case CHANNELMSG_OFFERCHANNEL:
  			atomic_inc(&vmbus_connection.offer_in_progress);
  			queue_work_on(vmbus_connection.connect_cpu,
  				      vmbus_connection.work_queue,
  				      &ctx->work);
  			break;
  
  		default:
  			queue_work(vmbus_connection.work_queue, &ctx->work);
  		}

  	} else
  		entry->message_handler(hdr);

  msg_handled:

  	vmbus_signal_eom(msg, message_type);

  }

  #ifdef CONFIG_PM_SLEEP

  /*
   * Fake RESCIND_CHANNEL messages to clean up hv_sock channels by force for
   * hibernation, because hv_sock connections can not persist across hibernation.
   */
  static void vmbus_force_channel_rescinded(struct vmbus_channel *channel)
  {
  	struct onmessage_work_context *ctx;
  	struct vmbus_channel_rescind_offer *rescind;
  
  	WARN_ON(!is_hvsock_channel(channel));
  
  	/*
  	 * sizeof(*ctx) is small and the allocation should really not fail,
  	 * otherwise the state of the hv_sock connections ends up in limbo.
  	 */
  	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL | __GFP_NOFAIL);
  
  	/*
  	 * So far, these are not really used by Linux. Just set them to the
  	 * reasonable values conforming to the definitions of the fields.
  	 */
  	ctx->msg.header.message_type = 1;
  	ctx->msg.header.payload_size = sizeof(*rescind);
  
  	/* These values are actually used by Linux. */
  	rescind = (struct vmbus_channel_rescind_offer *)ctx->msg.u.payload;
  	rescind->header.msgtype = CHANNELMSG_RESCIND_CHANNELOFFER;
  	rescind->child_relid = channel->offermsg.child_relid;
  
  	INIT_WORK(&ctx->work, vmbus_onmessage_work);
  
  	queue_work_on(vmbus_connection.connect_cpu,
  		      vmbus_connection.work_queue,
  		      &ctx->work);
  }

  #endif /* CONFIG_PM_SLEEP */

  
  /*

   * Direct callback for channels using other deferred processing
   */
  static void vmbus_channel_isr(struct vmbus_channel *channel)
  {
  	void (*callback_fn)(void *);
  
  	callback_fn = READ_ONCE(channel->onchannel_callback);
  	if (likely(callback_fn != NULL))
  		(*callback_fn)(channel->channel_callback_context);
  }
  
  /*

   * Schedule all channels with events pending
   */
  static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu)
  {
  	unsigned long *recv_int_page;
  	u32 maxbits, relid;
  
  	if (vmbus_proto_version < VERSION_WIN8) {
  		maxbits = MAX_NUM_CHANNELS_SUPPORTED;
  		recv_int_page = vmbus_connection.recv_int_page;
  	} else {
  		/*
  		 * When the host is win8 and beyond, the event page
  		 * can be directly checked to get the id of the channel
  		 * that has the interrupt pending.
  		 */
  		void *page_addr = hv_cpu->synic_event_page;
  		union hv_synic_event_flags *event
  			= (union hv_synic_event_flags *)page_addr +
  						 VMBUS_MESSAGE_SINT;
  
  		maxbits = HV_EVENT_FLAGS_COUNT;
  		recv_int_page = event->flags;
  	}
  
  	if (unlikely(!recv_int_page))
  		return;
  
  	for_each_set_bit(relid, recv_int_page, maxbits) {
  		struct vmbus_channel *channel;
  
  		if (!sync_test_and_clear_bit(relid, recv_int_page))
  			continue;
  
  		/* Special case - vmbus channel protocol msg */
  		if (relid == 0)
  			continue;

  		rcu_read_lock();

  		/* Find channel based on relid */

  		list_for_each_entry_rcu(channel, &hv_cpu->chan_list, percpu_list) {

  			if (channel->offermsg.child_relid != relid)
  				continue;

  			if (channel->rescind)
  				continue;

  			trace_vmbus_chan_sched(channel);

  			++channel->interrupts;

  			switch (channel->callback_mode) {
  			case HV_CALL_ISR:
  				vmbus_channel_isr(channel);

  				break;

  
  			case HV_CALL_BATCHED:
  				hv_begin_read(&channel->inbound);
  				/* fallthrough */
  			case HV_CALL_DIRECT:
  				tasklet_schedule(&channel->callback_event);

  			}
  		}

  
  		rcu_read_unlock();

  	}
  }

  static void vmbus_isr(void)

  {

  	struct hv_per_cpu_context *hv_cpu
  		= this_cpu_ptr(hv_context.cpu_context);
  	void *page_addr = hv_cpu->synic_event_page;

  	struct hv_message *msg;
  	union hv_synic_event_flags *event;

  	bool handled = false;

  	if (unlikely(page_addr == NULL))

  		return;

  
  	event = (union hv_synic_event_flags *)page_addr +
  					 VMBUS_MESSAGE_SINT;

  	/*
  	 * Check for events before checking for messages. This is the order
  	 * in which events and messages are checked in Windows guests on
  	 * Hyper-V, and the Windows team suggested we do the same.
  	 */

  	if ((vmbus_proto_version == VERSION_WS2008) ||
  		(vmbus_proto_version == VERSION_WIN7)) {

  		/* Since we are a child, we only need to check bit 0 */

  		if (sync_test_and_clear_bit(0, event->flags))

  			handled = true;

  	} else {
  		/*
  		 * Our host is win8 or above. The signaling mechanism
  		 * has changed and we can directly look at the event page.
  		 * If bit n is set then we have an interrup on the channel
  		 * whose id is n.
  		 */

  		handled = true;

  	}

  	if (handled)

  		vmbus_chan_sched(hv_cpu);

  	page_addr = hv_cpu->synic_message_page;

  	msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
  
  	/* 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_stimer0_isr();
  			vmbus_signal_eom(msg, HVMSG_TIMER_EXPIRED);
  		} else

  			tasklet_schedule(&hv_cpu->msg_dpc);

  	}

  
  	add_interrupt_randomness(HYPERVISOR_CALLBACK_VECTOR, 0);

  }

  /*
   * Boolean to control whether to report panic messages over Hyper-V.
   *
   * It can be set via /proc/sys/kernel/hyperv/record_panic_msg
   */
  static int sysctl_record_panic_msg = 1;
  
  /*
   * Callback from kmsg_dump. Grab as much as possible from the end of the kmsg
   * buffer and call into Hyper-V to transfer the data.
   */
  static void hv_kmsg_dump(struct kmsg_dumper *dumper,
  			 enum kmsg_dump_reason reason)
  {
  	size_t bytes_written;
  	phys_addr_t panic_pa;
  
  	/* We are only interested in panics. */
  	if ((reason != KMSG_DUMP_PANIC) || (!sysctl_record_panic_msg))
  		return;
  
  	panic_pa = virt_to_phys(hv_panic_page);
  
  	/*
  	 * Write dump contents to the page. No need to synchronize; panic should
  	 * be single-threaded.
  	 */

  	kmsg_dump_get_buffer(dumper, true, hv_panic_page, PAGE_SIZE,
  			     &bytes_written);
  	if (bytes_written)
  		hyperv_report_panic_msg(panic_pa, bytes_written);

  }
  
  static struct kmsg_dumper hv_kmsg_dumper = {
  	.dump = hv_kmsg_dump,
  };
  
  static struct ctl_table_header *hv_ctl_table_hdr;

  
  /*
   * sysctl option to allow the user to control whether kmsg data should be
   * reported to Hyper-V on panic.
   */
  static struct ctl_table hv_ctl_table[] = {
  	{
  		.procname       = "hyperv_record_panic_msg",
  		.data           = &sysctl_record_panic_msg,
  		.maxlen         = sizeof(int),
  		.mode           = 0644,
  		.proc_handler   = proc_dointvec_minmax,

  		.extra1		= SYSCTL_ZERO,
  		.extra2		= SYSCTL_ONE

  	},
  	{}
  };
  
  static struct ctl_table hv_root_table[] = {
  	{
  		.procname	= "kernel",
  		.mode		= 0555,
  		.child		= hv_ctl_table
  	},
  	{}
  };

  /*

   * vmbus_bus_init -Main vmbus driver initialization routine.
   *
   * Here, we

   *	- initialize the vmbus driver context

   *	- invoke the vmbus hv main init routine

   *	- retrieve the channel offers

   */

  static int vmbus_bus_init(void)

  {

  	int ret;

  	/* Hypervisor initialization...setup hypercall page..etc */
  	ret = hv_init();

  	if (ret != 0) {

  		pr_err("Unable to initialize the hypervisor - 0x%x
  ", ret);

  		return ret;

  	}

  	ret = bus_register(&hv_bus);

  	if (ret)

  		return ret;

  	hv_setup_vmbus_irq(vmbus_isr);

  	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 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_cpuhp;

  	hyperv_cpuhp_online = ret;

  	ret = vmbus_connect();

  	if (ret)

  		goto err_connect;

  	/*
  	 * Only register if the crash MSRs are available
  	 */

  	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {

  		u64 hyperv_crash_ctl;
  		/*
  		 * Sysctl registration is not fatal, since by default
  		 * reporting is enabled.
  		 */
  		hv_ctl_table_hdr = register_sysctl_table(hv_root_table);
  		if (!hv_ctl_table_hdr)
  			pr_err("Hyper-V: sysctl table register error");
  
  		/*
  		 * Register for panic kmsg callback only if the right
  		 * capability is supported by the hypervisor.
  		 */

  		hv_get_crash_ctl(hyperv_crash_ctl);

  		if (hyperv_crash_ctl & HV_CRASH_CTL_CRASH_NOTIFY_MSG) {
  			hv_panic_page = (void *)get_zeroed_page(GFP_KERNEL);
  			if (hv_panic_page) {
  				ret = kmsg_dump_register(&hv_kmsg_dumper);
  				if (ret)
  					pr_err("Hyper-V: kmsg dump register "
  						"error 0x%x
  ", ret);
  			} else
  				pr_err("Hyper-V: panic message page memory "
  					"allocation failed");
  		}

  		register_die_notifier(&hyperv_die_block);

  		atomic_notifier_chain_register(&panic_notifier_list,
  					       &hyperv_panic_block);
  	}

  	vmbus_request_offers();

  	return 0;

  err_connect:

  	cpuhp_remove_state(hyperv_cpuhp_online);

  err_cpuhp:
  	hv_stimer_free();

  err_alloc:
  	hv_synic_free();

  	hv_remove_vmbus_irq();

  	bus_unregister(&hv_bus);

  	free_page((unsigned long)hv_panic_page);

  	unregister_sysctl_table(hv_ctl_table_hdr);
  	hv_ctl_table_hdr = NULL;

  	return ret;

  }

  /**

   * __vmbus_child_driver_register() - Register a vmbus's driver
   * @hv_driver: Pointer to driver structure you want to register

   * @owner: owner module of the drv
   * @mod_name: module name string

   *
   * Registers the given driver with Linux through the 'driver_register()' call

   * and sets up the hyper-v vmbus handling for this driver.

   * It will return the state of the 'driver_register()' call.
   *

   */

  int __vmbus_driver_register(struct hv_driver *hv_driver, struct module *owner, const char *mod_name)

  {

  	int ret;

  	pr_info("registering driver %s
  ", hv_driver->name);

  	ret = vmbus_exists();
  	if (ret < 0)
  		return ret;

  	hv_driver->driver.name = hv_driver->name;
  	hv_driver->driver.owner = owner;
  	hv_driver->driver.mod_name = mod_name;
  	hv_driver->driver.bus = &hv_bus;

  	spin_lock_init(&hv_driver->dynids.lock);
  	INIT_LIST_HEAD(&hv_driver->dynids.list);

  	ret = driver_register(&hv_driver->driver);

  	return ret;

  }

  EXPORT_SYMBOL_GPL(__vmbus_driver_register);

  /**

   * vmbus_driver_unregister() - Unregister a vmbus's driver

   * @hv_driver: Pointer to driver structure you want to
   *             un-register

   *

   * Un-register the given driver that was previous registered with a call to
   * vmbus_driver_register()

   */

  void vmbus_driver_unregister(struct hv_driver *hv_driver)

  {

  	pr_info("unregistering driver %s
  ", hv_driver->name);

  	if (!vmbus_exists()) {

  		driver_unregister(&hv_driver->driver);

  		vmbus_free_dynids(hv_driver);
  	}

  }

  EXPORT_SYMBOL_GPL(vmbus_driver_unregister);

  
  /*
   * Called when last reference to channel is gone.
   */
  static void vmbus_chan_release(struct kobject *kobj)
  {
  	struct vmbus_channel *channel
  		= container_of(kobj, struct vmbus_channel, kobj);
  
  	kfree_rcu(channel, rcu);
  }
  
  struct vmbus_chan_attribute {
  	struct attribute attr;

  	ssize_t (*show)(struct vmbus_channel *chan, char *buf);

  	ssize_t (*store)(struct vmbus_channel *chan,
  			 const char *buf, size_t count);
  };
  #define VMBUS_CHAN_ATTR(_name, _mode, _show, _store) \
  	struct vmbus_chan_attribute chan_attr_##_name \
  		= __ATTR(_name, _mode, _show, _store)
  #define VMBUS_CHAN_ATTR_RW(_name) \
  	struct vmbus_chan_attribute chan_attr_##_name = __ATTR_RW(_name)
  #define VMBUS_CHAN_ATTR_RO(_name) \
  	struct vmbus_chan_attribute chan_attr_##_name = __ATTR_RO(_name)
  #define VMBUS_CHAN_ATTR_WO(_name) \
  	struct vmbus_chan_attribute chan_attr_##_name = __ATTR_WO(_name)
  
  static ssize_t vmbus_chan_attr_show(struct kobject *kobj,
  				    struct attribute *attr, char *buf)
  {
  	const struct vmbus_chan_attribute *attribute
  		= container_of(attr, struct vmbus_chan_attribute, attr);

  	struct vmbus_channel *chan

  		= container_of(kobj, struct vmbus_channel, kobj);
  
  	if (!attribute->show)
  		return -EIO;
  
  	return attribute->show(chan, buf);
  }
  
  static const struct sysfs_ops vmbus_chan_sysfs_ops = {
  	.show = vmbus_chan_attr_show,
  };

  static ssize_t out_mask_show(struct vmbus_channel *channel, char *buf)

  {

  	struct hv_ring_buffer_info *rbi = &channel->outbound;
  	ssize_t ret;

  	mutex_lock(&rbi->ring_buffer_mutex);
  	if (!rbi->ring_buffer) {
  		mutex_unlock(&rbi->ring_buffer_mutex);

  		return -EINVAL;

  	}

  	ret = sprintf(buf, "%u
  ", rbi->ring_buffer->interrupt_mask);
  	mutex_unlock(&rbi->ring_buffer_mutex);
  	return ret;

  }

  static VMBUS_CHAN_ATTR_RO(out_mask);

  static ssize_t in_mask_show(struct vmbus_channel *channel, char *buf)

  {

  	struct hv_ring_buffer_info *rbi = &channel->inbound;
  	ssize_t ret;

  	mutex_lock(&rbi->ring_buffer_mutex);
  	if (!rbi->ring_buffer) {
  		mutex_unlock(&rbi->ring_buffer_mutex);

  		return -EINVAL;

  	}

  	ret = sprintf(buf, "%u
  ", rbi->ring_buffer->interrupt_mask);
  	mutex_unlock(&rbi->ring_buffer_mutex);
  	return ret;

  }

  static VMBUS_CHAN_ATTR_RO(in_mask);

  static ssize_t read_avail_show(struct vmbus_channel *channel, char *buf)

  {

  	struct hv_ring_buffer_info *rbi = &channel->inbound;
  	ssize_t ret;

  	mutex_lock(&rbi->ring_buffer_mutex);
  	if (!rbi->ring_buffer) {
  		mutex_unlock(&rbi->ring_buffer_mutex);

  		return -EINVAL;

  	}

  	ret = sprintf(buf, "%u
  ", hv_get_bytes_to_read(rbi));
  	mutex_unlock(&rbi->ring_buffer_mutex);
  	return ret;

  }

  static VMBUS_CHAN_ATTR_RO(read_avail);

  static ssize_t write_avail_show(struct vmbus_channel *channel, char *buf)

  {

  	struct hv_ring_buffer_info *rbi = &channel->outbound;
  	ssize_t ret;

  	mutex_lock(&rbi->ring_buffer_mutex);
  	if (!rbi->ring_buffer) {
  		mutex_unlock(&rbi->ring_buffer_mutex);

  		return -EINVAL;

  	}

  	ret = sprintf(buf, "%u
  ", hv_get_bytes_to_write(rbi));
  	mutex_unlock(&rbi->ring_buffer_mutex);
  	return ret;

  }

  static VMBUS_CHAN_ATTR_RO(write_avail);

  static ssize_t show_target_cpu(struct vmbus_channel *channel, char *buf)

  {
  	return sprintf(buf, "%u
  ", channel->target_cpu);
  }

  static VMBUS_CHAN_ATTR(cpu, S_IRUGO, show_target_cpu, NULL);

  static ssize_t channel_pending_show(struct vmbus_channel *channel,

  				    char *buf)
  {
  	return sprintf(buf, "%d
  ",
  		       channel_pending(channel,
  				       vmbus_connection.monitor_pages[1]));
  }

  static VMBUS_CHAN_ATTR(pending, S_IRUGO, channel_pending_show, NULL);

  static ssize_t channel_latency_show(struct vmbus_channel *channel,

  				    char *buf)
  {
  	return sprintf(buf, "%d
  ",
  		       channel_latency(channel,
  				       vmbus_connection.monitor_pages[1]));
  }

  static VMBUS_CHAN_ATTR(latency, S_IRUGO, channel_latency_show, NULL);

  static ssize_t channel_interrupts_show(struct vmbus_channel *channel, char *buf)

  {
  	return sprintf(buf, "%llu
  ", channel->interrupts);
  }

  static VMBUS_CHAN_ATTR(interrupts, S_IRUGO, channel_interrupts_show, NULL);

  static ssize_t channel_events_show(struct vmbus_channel *channel, char *buf)

  {
  	return sprintf(buf, "%llu
  ", channel->sig_events);
  }

  static VMBUS_CHAN_ATTR(events, S_IRUGO, channel_events_show, NULL);

  static ssize_t channel_intr_in_full_show(struct vmbus_channel *channel,

  					 char *buf)
  {
  	return sprintf(buf, "%llu
  ",
  		       (unsigned long long)channel->intr_in_full);
  }
  static VMBUS_CHAN_ATTR(intr_in_full, 0444, channel_intr_in_full_show, NULL);

  static ssize_t channel_intr_out_empty_show(struct vmbus_channel *channel,

  					   char *buf)
  {
  	return sprintf(buf, "%llu
  ",
  		       (unsigned long long)channel->intr_out_empty);
  }
  static VMBUS_CHAN_ATTR(intr_out_empty, 0444, channel_intr_out_empty_show, NULL);

  static ssize_t channel_out_full_first_show(struct vmbus_channel *channel,

  					   char *buf)
  {
  	return sprintf(buf, "%llu
  ",
  		       (unsigned long long)channel->out_full_first);
  }
  static VMBUS_CHAN_ATTR(out_full_first, 0444, channel_out_full_first_show, NULL);

  static ssize_t channel_out_full_total_show(struct vmbus_channel *channel,

  					   char *buf)
  {
  	return sprintf(buf, "%llu
  ",
  		       (unsigned long long)channel->out_full_total);
  }
  static VMBUS_CHAN_ATTR(out_full_total, 0444, channel_out_full_total_show, NULL);

  static ssize_t subchannel_monitor_id_show(struct vmbus_channel *channel,

  					  char *buf)
  {
  	return sprintf(buf, "%u
  ", channel->offermsg.monitorid);
  }
  static VMBUS_CHAN_ATTR(monitor_id, S_IRUGO, subchannel_monitor_id_show, NULL);

  static ssize_t subchannel_id_show(struct vmbus_channel *channel,

  				  char *buf)
  {
  	return sprintf(buf, "%u
  ",
  		       channel->offermsg.offer.sub_channel_index);
  }
  static VMBUS_CHAN_ATTR_RO(subchannel_id);

  static struct attribute *vmbus_chan_attrs[] = {
  	&chan_attr_out_mask.attr,
  	&chan_attr_in_mask.attr,
  	&chan_attr_read_avail.attr,
  	&chan_attr_write_avail.attr,
  	&chan_attr_cpu.attr,
  	&chan_attr_pending.attr,
  	&chan_attr_latency.attr,

  	&chan_attr_interrupts.attr,
  	&chan_attr_events.attr,

  	&chan_attr_intr_in_full.attr,
  	&chan_attr_intr_out_empty.attr,
  	&chan_attr_out_full_first.attr,
  	&chan_attr_out_full_total.attr,

  	&chan_attr_monitor_id.attr,
  	&chan_attr_subchannel_id.attr,

  	NULL
  };

  /*
   * Channel-level attribute_group callback function. Returns the permission for
   * each attribute, and returns 0 if an attribute is not visible.
   */
  static umode_t vmbus_chan_attr_is_visible(struct kobject *kobj,
  					  struct attribute *attr, int idx)
  {
  	const struct vmbus_channel *channel =
  		container_of(kobj, struct vmbus_channel, kobj);
  
  	/* Hide the monitor attributes if the monitor mechanism is not used. */
  	if (!channel->offermsg.monitor_allocated &&
  	    (attr == &chan_attr_pending.attr ||
  	     attr == &chan_attr_latency.attr ||
  	     attr == &chan_attr_monitor_id.attr))
  		return 0;
  
  	return attr->mode;
  }
  
  static struct attribute_group vmbus_chan_group = {
  	.attrs = vmbus_chan_attrs,
  	.is_visible = vmbus_chan_attr_is_visible
  };

  static struct kobj_type vmbus_chan_ktype = {
  	.sysfs_ops = &vmbus_chan_sysfs_ops,
  	.release = vmbus_chan_release,

  };
  
  /*
   * vmbus_add_channel_kobj - setup a sub-directory under device/channels
   */
  int vmbus_add_channel_kobj(struct hv_device *dev, struct vmbus_channel *channel)
  {

  	const struct device *device = &dev->device;

  	struct kobject *kobj = &channel->kobj;
  	u32 relid = channel->offermsg.child_relid;
  	int ret;
  
  	kobj->kset = dev->channels_kset;
  	ret = kobject_init_and_add(kobj, &vmbus_chan_ktype, NULL,
  				   "%u", relid);
  	if (ret)
  		return ret;

  	ret = sysfs_create_group(kobj, &vmbus_chan_group);
  
  	if (ret) {
  		/*
  		 * The calling functions' error handling paths will cleanup the
  		 * empty channel directory.
  		 */
  		dev_err(device, "Unable to set up channel sysfs files
  ");
  		return ret;
  	}

  	kobject_uevent(kobj, KOBJ_ADD);
  
  	return 0;
  }

  /*

   * vmbus_remove_channel_attr_group - remove the channel's attribute group
   */
  void vmbus_remove_channel_attr_group(struct vmbus_channel *channel)
  {
  	sysfs_remove_group(&channel->kobj, &vmbus_chan_group);
  }
  
  /*

   * vmbus_device_create - Creates and registers a new child device

   * on the vmbus.

   */

  struct hv_device *vmbus_device_create(const guid_t *type,
  				      const guid_t *instance,

  				      struct vmbus_channel *channel)

  {

  	struct hv_device *child_device_obj;

  	child_device_obj = kzalloc(sizeof(struct hv_device), GFP_KERNEL);
  	if (!child_device_obj) {

  		pr_err("Unable to allocate device object for child device
  ");

  		return NULL;
  	}

  	child_device_obj->channel = channel;

  	guid_copy(&child_device_obj->dev_type, type);
  	guid_copy(&child_device_obj->dev_instance, instance);

  	child_device_obj->vendor_id = 0x1414; /* MSFT vendor ID */

  	return child_device_obj;
  }

  /*

   * vmbus_device_register - Register the child device

   */

  int vmbus_device_register(struct hv_device *child_device_obj)

  {

  	struct kobject *kobj = &child_device_obj->device.kobj;
  	int ret;

  	dev_set_name(&child_device_obj->device, "%pUl",

  		     child_device_obj->channel->offermsg.offer.if_instance.b);

  	child_device_obj->device.bus = &hv_bus;

  	child_device_obj->device.parent = &hv_acpi_dev->dev;

  	child_device_obj->device.release = vmbus_device_release;

  	/*
  	 * Register with the LDM. This will kick off the driver/device
  	 * binding...which will eventually call vmbus_match() and vmbus_probe()
  	 */

  	ret = device_register(&child_device_obj->device);

  	if (ret) {

  		pr_err("Unable to register child device
  ");

  		return ret;
  	}
  
  	child_device_obj->channels_kset = kset_create_and_add("channels",
  							      NULL, kobj);
  	if (!child_device_obj->channels_kset) {
  		ret = -ENOMEM;
  		goto err_dev_unregister;
  	}
  
  	ret = vmbus_add_channel_kobj(child_device_obj,
  				     child_device_obj->channel);
  	if (ret) {
  		pr_err("Unable to register primary channeln");
  		goto err_kset_unregister;
  	}
  
  	return 0;
  
  err_kset_unregister:
  	kset_unregister(child_device_obj->channels_kset);

  err_dev_unregister:
  	device_unregister(&child_device_obj->device);

  	return ret;
  }

  /*

   * vmbus_device_unregister - Remove the specified child device

   * from the vmbus.

   */

  void vmbus_device_unregister(struct hv_device *device_obj)

  {

  	pr_debug("child device %s unregistered
  ",
  		dev_name(&device_obj->device));

  	kset_unregister(device_obj->channels_kset);

  	/*
  	 * Kick off the process of unregistering the device.
  	 * This will call vmbus_remove() and eventually vmbus_device_release()
  	 */

  	device_unregister(&device_obj->device);

  }

  /*

   * VMBUS is an acpi enumerated device. Get the information we

   * need from DSDT.

   */

  #define VTPM_BASE_ADDRESS 0xfed40000

  static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)

  {

  	resource_size_t start = 0;
  	resource_size_t end = 0;
  	struct resource *new_res;
  	struct resource **old_res = &hyperv_mmio;
  	struct resource **prev_res = NULL;

  	switch (res->type) {

  
  	/*
  	 * "Address" descriptors are for bus windows. Ignore
  	 * "memory" descriptors, which are for registers on
  	 * devices.
  	 */
  	case ACPI_RESOURCE_TYPE_ADDRESS32:
  		start = res->data.address32.address.minimum;
  		end = res->data.address32.address.maximum;

  		break;

  	case ACPI_RESOURCE_TYPE_ADDRESS64:

  		start = res->data.address64.address.minimum;
  		end = res->data.address64.address.maximum;

  		break;

  
  	default:
  		/* Unused resource type */
  		return AE_OK;

  	}

  	/*
  	 * Ignore ranges that are below 1MB, as they're not
  	 * necessary or useful here.
  	 */
  	if (end < 0x100000)
  		return AE_OK;
  
  	new_res = kzalloc(sizeof(*new_res), GFP_ATOMIC);
  	if (!new_res)
  		return AE_NO_MEMORY;
  
  	/* If this range overlaps the virtual TPM, truncate it. */
  	if (end > VTPM_BASE_ADDRESS && start < VTPM_BASE_ADDRESS)
  		end = VTPM_BASE_ADDRESS;
  
  	new_res->name = "hyperv mmio";
  	new_res->flags = IORESOURCE_MEM;
  	new_res->start = start;
  	new_res->end = end;

  	/*

  	 * If two ranges are adjacent, merge them.
  	 */

  	do {
  		if (!*old_res) {
  			*old_res = new_res;
  			break;
  		}

  		if (((*old_res)->end + 1) == new_res->start) {
  			(*old_res)->end = new_res->end;
  			kfree(new_res);
  			break;
  		}
  
  		if ((*old_res)->start == new_res->end + 1) {
  			(*old_res)->start = new_res->start;
  			kfree(new_res);
  			break;
  		}

  		if ((*old_res)->start > new_res->end) {

  			new_res->sibling = *old_res;
  			if (prev_res)
  				(*prev_res)->sibling = new_res;
  			*old_res = new_res;
  			break;
  		}
  
  		prev_res = old_res;
  		old_res = &(*old_res)->sibling;
  
  	} while (1);

  
  	return AE_OK;
  }

  static int vmbus_acpi_remove(struct acpi_device *device)
  {
  	struct resource *cur_res;
  	struct resource *next_res;
  
  	if (hyperv_mmio) {

  		if (fb_mmio) {
  			__release_region(hyperv_mmio, fb_mmio->start,
  					 resource_size(fb_mmio));
  			fb_mmio = NULL;
  		}

  		for (cur_res = hyperv_mmio; cur_res; cur_res = next_res) {
  			next_res = cur_res->sibling;
  			kfree(cur_res);
  		}
  	}
  
  	return 0;
  }

  static void vmbus_reserve_fb(void)
  {
  	int size;
  	/*
  	 * Make a claim for the frame buffer in the resource tree under the
  	 * first node, which will be the one below 4GB.  The length seems to
  	 * be underreported, particularly in a Generation 1 VM.  So start out
  	 * reserving a larger area and make it smaller until it succeeds.
  	 */
  
  	if (screen_info.lfb_base) {
  		if (efi_enabled(EFI_BOOT))
  			size = max_t(__u32, screen_info.lfb_size, 0x800000);
  		else
  			size = max_t(__u32, screen_info.lfb_size, 0x4000000);
  
  		for (; !fb_mmio && (size >= 0x100000); size >>= 1) {
  			fb_mmio = __request_region(hyperv_mmio,
  						   screen_info.lfb_base, size,
  						   fb_mmio_name, 0);
  		}
  	}
  }

  /**
   * vmbus_allocate_mmio() - Pick a memory-mapped I/O range.
   * @new:		If successful, supplied a pointer to the
   *			allocated MMIO space.
   * @device_obj:		Identifies the caller
   * @min:		Minimum guest physical address of the
   *			allocation
   * @max:		Maximum guest physical address
   * @size:		Size of the range to be allocated
   * @align:		Alignment of the range to be allocated
   * @fb_overlap_ok:	Whether this allocation can be allowed
   *			to overlap the video frame buffer.
   *
   * This function walks the resources granted to VMBus by the
   * _CRS object in the ACPI namespace underneath the parent
   * "bridge" whether that's a root PCI bus in the Generation 1
   * case or a Module Device in the Generation 2 case.  It then
   * attempts to allocate from the global MMIO pool in a way that
   * matches the constraints supplied in these parameters and by
   * that _CRS.
   *
   * Return: 0 on success, -errno on failure
   */
  int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
  			resource_size_t min, resource_size_t max,
  			resource_size_t size, resource_size_t align,
  			bool fb_overlap_ok)
  {

  	struct resource *iter, *shadow;

  	resource_size_t range_min, range_max, start;

  	const char *dev_n = dev_name(&device_obj->device);

  	int retval;

  
  	retval = -ENXIO;
  	down(&hyperv_mmio_lock);

  	/*
  	 * If overlaps with frame buffers are allowed, then first attempt to
  	 * make the allocation from within the reserved region.  Because it
  	 * is already reserved, no shadow allocation is necessary.
  	 */
  	if (fb_overlap_ok && fb_mmio && !(min > fb_mmio->end) &&
  	    !(max < fb_mmio->start)) {
  
  		range_min = fb_mmio->start;
  		range_max = fb_mmio->end;
  		start = (range_min + align - 1) & ~(align - 1);
  		for (; start + size - 1 <= range_max; start += align) {
  			*new = request_mem_region_exclusive(start, size, dev_n);
  			if (*new) {
  				retval = 0;
  				goto exit;
  			}
  		}
  	}

  	for (iter = hyperv_mmio; iter; iter = iter->sibling) {
  		if ((iter->start >= max) || (iter->end <= min))
  			continue;
  
  		range_min = iter->start;
  		range_max = iter->end;

  		start = (range_min + align - 1) & ~(align - 1);
  		for (; start + size - 1 <= range_max; start += align) {
  			shadow = __request_region(iter, start, size, NULL,
  						  IORESOURCE_BUSY);
  			if (!shadow)
  				continue;
  
  			*new = request_mem_region_exclusive(start, size, dev_n);
  			if (*new) {
  				shadow->name = (char *)*new;
  				retval = 0;
  				goto exit;

  			}

  			__release_region(iter, start, size);

  		}
  	}

  exit:
  	up(&hyperv_mmio_lock);
  	return retval;

  }
  EXPORT_SYMBOL_GPL(vmbus_allocate_mmio);

  /**

   * vmbus_free_mmio() - Free a memory-mapped I/O range.
   * @start:		Base address of region to release.
   * @size:		Size of the range to be allocated
   *
   * This function releases anything requested by
   * vmbus_mmio_allocate().
   */
  void vmbus_free_mmio(resource_size_t start, resource_size_t size)
  {

  	struct resource *iter;
  
  	down(&hyperv_mmio_lock);
  	for (iter = hyperv_mmio; iter; iter = iter->sibling) {
  		if ((iter->start >= start + size) || (iter->end <= start))
  			continue;
  
  		__release_region(iter, start, size);
  	}

  	release_mem_region(start, size);

  	up(&hyperv_mmio_lock);

  
  }
  EXPORT_SYMBOL_GPL(vmbus_free_mmio);

  static int vmbus_acpi_add(struct acpi_device *device)
  {
  	acpi_status result;

  	int ret_val = -ENODEV;

  	struct acpi_device *ancestor;

  	hv_acpi_dev = device;

  	result = acpi_walk_resources(device->handle, METHOD_NAME__CRS,

  					vmbus_walk_resources, NULL);

  	if (ACPI_FAILURE(result))
  		goto acpi_walk_err;
  	/*

  	 * Some ancestor of the vmbus acpi device (Gen1 or Gen2
  	 * firmware) is the VMOD that has the mmio ranges. Get that.

  	 */

  	for (ancestor = device->parent; ancestor; ancestor = ancestor->parent) {
  		result = acpi_walk_resources(ancestor->handle, METHOD_NAME__CRS,
  					     vmbus_walk_resources, NULL);

  
  		if (ACPI_FAILURE(result))

  			continue;

  		if (hyperv_mmio) {
  			vmbus_reserve_fb();

  			break;

  		}

  	}

  	ret_val = 0;
  
  acpi_walk_err:

  	complete(&probe_event);

  	if (ret_val)
  		vmbus_acpi_remove(device);

  	return ret_val;

  }

  #ifdef CONFIG_PM_SLEEP

  static int vmbus_bus_suspend(struct device *dev)
  {

  	struct vmbus_channel *channel, *sc;
  	unsigned long flags;

  
  	while (atomic_read(&vmbus_connection.offer_in_progress) != 0) {
  		/*
  		 * We wait here until the completion of any channel
  		 * offers that are currently in progress.
  		 */
  		msleep(1);
  	}
  
  	mutex_lock(&vmbus_connection.channel_mutex);
  	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
  		if (!is_hvsock_channel(channel))
  			continue;
  
  		vmbus_force_channel_rescinded(channel);
  	}
  	mutex_unlock(&vmbus_connection.channel_mutex);

  	/*
  	 * Wait until all the sub-channels and hv_sock channels have been
  	 * cleaned up. Sub-channels should be destroyed upon suspend, otherwise
  	 * they would conflict with the new sub-channels that will be created
  	 * in the resume path. hv_sock channels should also be destroyed, but
  	 * a hv_sock channel of an established hv_sock connection can not be
  	 * really destroyed since it may still be referenced by the userspace
  	 * application, so we just force the hv_sock channel to be rescinded
  	 * by vmbus_force_channel_rescinded(), and the userspace application
  	 * will thoroughly destroy the channel after hibernation.
  	 *
  	 * Note: the counter nr_chan_close_on_suspend may never go above 0 if
  	 * the VM has no sub-channel and hv_sock channel, e.g. a 1-vCPU VM.
  	 */
  	if (atomic_read(&vmbus_connection.nr_chan_close_on_suspend) > 0)
  		wait_for_completion(&vmbus_connection.ready_for_suspend_event);

  	WARN_ON(atomic_read(&vmbus_connection.nr_chan_fixup_on_resume) != 0);

  	mutex_lock(&vmbus_connection.channel_mutex);
  
  	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {

  		/*
  		 * Invalidate the field. Upon resume, vmbus_onoffer() will fix
  		 * up the field, and the other fields (if necessary).
  		 */
  		channel->offermsg.child_relid = INVALID_RELID;

  		if (is_hvsock_channel(channel)) {
  			if (!channel->rescind) {
  				pr_err("hv_sock channel not rescinded!
  ");
  				WARN_ON_ONCE(1);
  			}
  			continue;
  		}
  
  		spin_lock_irqsave(&channel->lock, flags);
  		list_for_each_entry(sc, &channel->sc_list, sc_list) {
  			pr_err("Sub-channel not deleted!
  ");
  			WARN_ON_ONCE(1);
  		}
  		spin_unlock_irqrestore(&channel->lock, flags);

  
  		atomic_inc(&vmbus_connection.nr_chan_fixup_on_resume);

  	}
  
  	mutex_unlock(&vmbus_connection.channel_mutex);

  	vmbus_initiate_unload(false);
  
  	vmbus_connection.conn_state = DISCONNECTED;

  	/* Reset the event for the next resume. */
  	reinit_completion(&vmbus_connection.ready_for_resume_event);

  	return 0;
  }
  
  static int vmbus_bus_resume(struct device *dev)
  {
  	struct vmbus_channel_msginfo *msginfo;
  	size_t msgsize;
  	int ret;
  
  	/*
  	 * We only use the 'vmbus_proto_version', which was in use before
  	 * hibernation, to re-negotiate with the host.
  	 */
  	if (vmbus_proto_version == VERSION_INVAL ||
  	    vmbus_proto_version == 0) {
  		pr_err("Invalid proto version = 0x%x
  ", vmbus_proto_version);
  		return -EINVAL;
  	}
  
  	msgsize = sizeof(*msginfo) +
  		  sizeof(struct vmbus_channel_initiate_contact);
  
  	msginfo = kzalloc(msgsize, GFP_KERNEL);
  
  	if (msginfo == NULL)
  		return -ENOMEM;
  
  	ret = vmbus_negotiate_version(msginfo, vmbus_proto_version);
  
  	kfree(msginfo);
  
  	if (ret != 0)
  		return ret;

  	WARN_ON(atomic_read(&vmbus_connection.nr_chan_fixup_on_resume) == 0);

  	vmbus_request_offers();

  	wait_for_completion(&vmbus_connection.ready_for_resume_event);