Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2709 insertions, 0 deletions

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
new file mode 100644
index 000000000..e99400f3a
--- /dev/null
+++ b/drivers/hv/vmbus_drv.c
@@ -0,0 +1,2709 @@
+// 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 <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/kernel.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;
+
+/* Values parsed from ACPI DSDT */
+static int vmbus_irq;
+int vmbus_interrupt;
+
+/*
+ * 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;
+
+static int hyperv_report_reg(void)
+{
+	return !sysctl_record_panic_msg || !hv_panic_page;
+}
+
+static int hyperv_panic_event(struct notifier_block *nb, unsigned long val,
+			      void *args)
+{
+	struct pt_regs *regs;
+
+	vmbus_initiate_unload(true);
+
+	/*
+	 * Hyper-V should be notified only once about a panic.  If we will be
+	 * doing hyperv_report_panic_msg() later with kmsg data, don't do
+	 * the notification here.
+	 */
+	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE
+	    && hyperv_report_reg()) {
+		regs = current_pt_regs();
+		hyperv_report_panic(regs, val, false);
+	}
+	return NOTIFY_DONE;
+}
+
+static int hyperv_die_event(struct notifier_block *nb, unsigned long val,
+			    void *args)
+{
+	struct die_args *die = args;
+	struct pt_regs *regs = die->regs;
+
+	/* Don't notify Hyper-V if the die event is other than oops */
+	if (val != DIE_OOPS)
+		return NOTIFY_DONE;
+
+	/*
+	 * Hyper-V should be notified only once about a panic.  If we will be
+	 * doing hyperv_report_panic_msg() later with kmsg data, don't do
+	 * the notification here.
+	 */
+	if (hyperv_report_reg())
+		hyperv_report_panic(regs, val, true);
+	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_MUTEX(hyperv_mmio_lock);
+
+static int vmbus_exists(void)
+{
+	if (hv_acpi_dev == NULL)
+		return -ENODEV;
+
+	return 0;
+}
+
+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\n", 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\n", 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\n", 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}\n",
+		       &hv_dev->channel->offermsg.offer.if_type);
+}
+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}\n",
+		       &hv_dev->channel->offermsg.offer.if_instance);
+}
+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);
+
+	return sprintf(buf, "vmbus:%*phN\n", UUID_SIZE, &hv_dev->dev_type);
+}
+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\n", cpu_to_node(hv_dev->channel->target_cpu));
+}
+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\n",
+		       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\n",
+		       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\n",
+		       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\n",
+		       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\n",
+		       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\n",
+		       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\n", 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\n", 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\n", 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\n", 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\n", 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\n", 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\n", 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\n", 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\n", 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\n", 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;
+	int buf_size = PAGE_SIZE, n_written, tot_written;
+	struct list_head *cur;
+
+	if (!channel)
+		return -ENODEV;
+
+	mutex_lock(&vmbus_connection.channel_mutex);
+
+	tot_written = snprintf(buf, buf_size, "%u:%u\n",
+		channel->offermsg.child_relid, channel->target_cpu);
+
+	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\n",
+				     cur_sc->offermsg.child_relid,
+				     cur_sc->target_cpu);
+		tot_written += n_written;
+	}
+
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	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\n", 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\n", 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, '\n');
+	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\n", 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);
+	const char *format = "MODALIAS=vmbus:%*phN";
+
+	return add_uevent_var(env, format, UUID_SIZE, &dev->dev_type);
+}
+
+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)\n",
+			       dev_name(child_device), ret);
+
+	} else {
+		pr_err("probe not set for driver %s\n",
+		       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);
+}
+#else
+#define vmbus_suspend NULL
+#define vmbus_resume NULL
+#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;
+
+	hv_debug_rm_dev_dir(hv_dev);
+
+	mutex_lock(&vmbus_connection.channel_mutex);
+	hv_process_channel_removal(channel);
+	mutex_unlock(&vmbus_connection.channel_mutex);
+	kfree(hv_dev);
+}
+
+/*
+ * Note: we must use the "noirq" ops: see the comment before vmbus_bus_pm.
+ *
+ * suspend_noirq/resume_noirq are set to NULL to support Suspend-to-Idle: we
+ * shouldn't suspend the vmbus devices upon Suspend-to-Idle, otherwise there
+ * is no way to wake up a Generation-2 VM.
+ *
+ * The other 4 ops are for hibernation.
+ */
+
+static const struct dev_pm_ops vmbus_pm = {
+	.suspend_noirq	= NULL,
+	.resume_noirq	= NULL,
+	.freeze_noirq	= vmbus_suspend,
+	.thaw_noirq	= vmbus_resume,
+	.poweroff_noirq	= vmbus_suspend,
+	.restore_noirq	= 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 {
+		struct hv_message_header header;
+		u8 payload[];
+	} 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((struct vmbus_channel_message_header *)
+			&ctx->msg.payload);
+	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;
+
+	/*
+	 * 'enum vmbus_channel_message_type' is supposed to always be 'u32' as
+	 * it is being used in 'struct vmbus_channel_message_header' definition
+	 * which is supposed to match hypervisor ABI.
+	 */
+	BUILD_BUG_ON(sizeof(enum vmbus_channel_message_type) != sizeof(u32));
+
+	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\n", hdr->msgtype);
+		goto msg_handled;
+	}
+
+	if (msg->header.payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT) {
+		WARN_ONCE(1, "payload size is too large (%d)\n",
+			  msg->header.payload_size);
+		goto msg_handled;
+	}
+
+	entry = &channel_message_table[hdr->msgtype];
+
+	if (!entry->message_handler)
+		goto msg_handled;
+
+	if (msg->header.payload_size < entry->min_payload_len) {
+		WARN_ONCE(1, "message too short: msgtype=%d len=%d\n",
+			  hdr->msgtype, msg->header.payload_size);
+		goto msg_handled;
+	}
+
+	if (entry->handler_type	== VMHT_BLOCKING) {
+		ctx = kmalloc(sizeof(*ctx) + msg->header.payload_size,
+			      GFP_ATOMIC);
+		if (ctx == NULL)
+			return;
+
+		INIT_WORK(&ctx->work, vmbus_onmessage_work);
+		memcpy(&ctx->msg, msg, sizeof(msg->header) +
+		       msg->header.payload_size);
+
+		/*
+		 * The host can generate a rescind message while we
+		 * may still be handling the original offer. We deal with
+		 * this condition by relying on the synchronization provided
+		 * by offer_in_progress and by channel_mutex.  See also the
+		 * inline comments in vmbus_onoffer_rescind().
+		 */
+		switch (hdr->msgtype) {
+		case CHANNELMSG_RESCIND_CHANNELOFFER:
+			/*
+			 * If we are handling the rescind message;
+			 * schedule the work on the global work queue.
+			 *
+			 * The OFFER message and the RESCIND message should
+			 * not be handled by the same serialized work queue,
+			 * because the OFFER handler may call vmbus_open(),
+			 * which tries to open the channel by sending an
+			 * OPEN_CHANNEL message to the host and waits for
+			 * the host's response; however, if the host has
+			 * rescinded the channel before it receives the
+			 * OPEN_CHANNEL message, the host just silently
+			 * ignores the OPEN_CHANNEL message; as a result,
+			 * the guest's OFFER handler hangs for ever, if we
+			 * handle the RESCIND message in the same serialized
+			 * work queue: the RESCIND handler can not start to
+			 * run before the OFFER handler finishes.
+			 */
+			schedule_work(&ctx->work);
+			break;
+
+		case CHANNELMSG_OFFERCHANNEL:
+			/*
+			 * The host sends the offer message of a given channel
+			 * before sending the rescind message of the same
+			 * channel.  These messages are sent to the guest's
+			 * connect CPU; the guest then starts processing them
+			 * in the tasklet handler on this CPU:
+			 *
+			 * VMBUS_CONNECT_CPU
+			 *
+			 * [vmbus_on_msg_dpc()]
+			 * atomic_inc()  // CHANNELMSG_OFFERCHANNEL
+			 * queue_work()
+			 * ...
+			 * [vmbus_on_msg_dpc()]
+			 * schedule_work()  // CHANNELMSG_RESCIND_CHANNELOFFER
+			 *
+			 * We rely on the memory-ordering properties of the
+			 * queue_work() and schedule_work() primitives, which
+			 * guarantee that the atomic increment will be visible
+			 * to the CPUs which will execute the offer & rescind
+			 * works by the time these works will start execution.
+			 */
+			atomic_inc(&vmbus_connection.offer_in_progress);
+			fallthrough;
+
+		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));
+
+	/*
+	 * Allocation size 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) + sizeof(*rescind),
+		      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.payload;
+	rescind->header.msgtype = CHANNELMSG_RESCIND_CHANNELOFFER;
+	rescind->child_relid = channel->offermsg.child_relid;
+
+	INIT_WORK(&ctx->work, vmbus_onmessage_work);
+
+	queue_work(vmbus_connection.work_queue, &ctx->work);
+}
+#endif /* CONFIG_PM_SLEEP */
+
+/*
+ * 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) {
+		void (*callback_fn)(void *context);
+		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;
+
+		/*
+		 * Pairs with the kfree_rcu() in vmbus_chan_release().
+		 * Guarantees that the channel data structure doesn't
+		 * get freed while the channel pointer below is being
+		 * dereferenced.
+		 */
+		rcu_read_lock();
+
+		/* Find channel based on relid */
+		channel = relid2channel(relid);
+		if (channel == NULL)
+			goto sched_unlock_rcu;
+
+		if (channel->rescind)
+			goto sched_unlock_rcu;
+
+		/*
+		 * Make sure that the ring buffer data structure doesn't get
+		 * freed while we dereference the ring buffer pointer.  Test
+		 * for the channel's onchannel_callback being NULL within a
+		 * sched_lock critical section.  See also the inline comments
+		 * in vmbus_reset_channel_cb().
+		 */
+		spin_lock(&channel->sched_lock);
+
+		callback_fn = channel->onchannel_callback;
+		if (unlikely(callback_fn == NULL))
+			goto sched_unlock;
+
+		trace_vmbus_chan_sched(channel);
+
+		++channel->interrupts;
+
+		switch (channel->callback_mode) {
+		case HV_CALL_ISR:
+			(*callback_fn)(channel->channel_callback_context);
+			break;
+
+		case HV_CALL_BATCHED:
+			hv_begin_read(&channel->inbound);
+			fallthrough;
+		case HV_CALL_DIRECT:
+			tasklet_schedule(&channel->callback_event);
+		}
+
+sched_unlock:
+		spin_unlock(&channel->sched_lock);
+sched_unlock_rcu:
+		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(hv_get_vector());
+}
+
+/*
+ * 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, false, hv_panic_page, HV_HYP_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;
+
+	ret = hv_init();
+	if (ret != 0) {
+		pr_err("Unable to initialize the hypervisor - 0x%x\n", ret);
+		return ret;
+	}
+
+	ret = bus_register(&hv_bus);
+	if (ret)
+		return ret;
+
+	ret = hv_setup_vmbus_irq(vmbus_irq, vmbus_isr);
+	if (ret)
+		goto err_setup;
+
+	ret = hv_synic_alloc();
+	if (ret)
+		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 *)hv_alloc_hyperv_zeroed_page();
+			if (hv_panic_page) {
+				ret = kmsg_dump_register(&hv_kmsg_dumper);
+				if (ret) {
+					pr_err("Hyper-V: kmsg dump register "
+						"error 0x%x\n", ret);
+					hv_free_hyperv_page(
+					    (unsigned long)hv_panic_page);
+					hv_panic_page = NULL;
+				}
+			} else
+				pr_err("Hyper-V: panic message page memory "
+					"allocation failed");
+		}
+
+		register_die_notifier(&hyperv_die_block);
+	}
+
+	/*
+	 * Always register the panic notifier because we need to unload
+	 * the VMbus channel connection to prevent any VMbus
+	 * activity after the VM panics.
+	 */
+	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_synic_free();
+err_alloc:
+	hv_remove_vmbus_irq();
+err_setup:
+	bus_unregister(&hv_bus);
+	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\n", 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\n", 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 ssize_t vmbus_chan_attr_store(struct kobject *kobj,
+				     struct attribute *attr, const char *buf,
+				     size_t count)
+{
+	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->store)
+		return -EIO;
+
+	return attribute->store(chan, buf, count);
+}
+
+static const struct sysfs_ops vmbus_chan_sysfs_ops = {
+	.show = vmbus_chan_attr_show,
+	.store = vmbus_chan_attr_store,
+};
+
+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\n", 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\n", 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\n", 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\n", hv_get_bytes_to_write(rbi));
+	mutex_unlock(&rbi->ring_buffer_mutex);
+	return ret;
+}
+static VMBUS_CHAN_ATTR_RO(write_avail);
+
+static ssize_t target_cpu_show(struct vmbus_channel *channel, char *buf)
+{
+	return sprintf(buf, "%u\n", channel->target_cpu);
+}
+static ssize_t target_cpu_store(struct vmbus_channel *channel,
+				const char *buf, size_t count)
+{
+	u32 target_cpu, origin_cpu;
+	ssize_t ret = count;
+
+	if (vmbus_proto_version < VERSION_WIN10_V4_1)
+		return -EIO;
+
+	if (sscanf(buf, "%uu", &target_cpu) != 1)
+		return -EIO;
+
+	/* Validate target_cpu for the cpumask_test_cpu() operation below. */
+	if (target_cpu >= nr_cpumask_bits)
+		return -EINVAL;
+
+	/* No CPUs should come up or down during this. */
+	cpus_read_lock();
+
+	if (!cpu_online(target_cpu)) {
+		cpus_read_unlock();
+		return -EINVAL;
+	}
+
+	/*
+	 * Synchronizes target_cpu_store() and channel closure:
+	 *
+	 * { Initially: state = CHANNEL_OPENED }
+	 *
+	 * CPU1				CPU2
+	 *
+	 * [target_cpu_store()]		[vmbus_disconnect_ring()]
+	 *
+	 * LOCK channel_mutex		LOCK channel_mutex
+	 * LOAD r1 = state		LOAD r2 = state
+	 * IF (r1 == CHANNEL_OPENED)	IF (r2 == CHANNEL_OPENED)
+	 *   SEND MODIFYCHANNEL		  STORE state = CHANNEL_OPEN
+	 *   [...]			  SEND CLOSECHANNEL
+	 * UNLOCK channel_mutex		UNLOCK channel_mutex
+	 *
+	 * Forbids: r1 == r2 == CHANNEL_OPENED (i.e., CPU1's LOCK precedes
+	 * 		CPU2's LOCK) && CPU2's SEND precedes CPU1's SEND
+	 *
+	 * Note.  The host processes the channel messages "sequentially", in
+	 * the order in which they are received on a per-partition basis.
+	 */
+	mutex_lock(&vmbus_connection.channel_mutex);
+
+	/*
+	 * Hyper-V will ignore MODIFYCHANNEL messages for "non-open" channels;
+	 * avoid sending the message and fail here for such channels.
+	 */
+	if (channel->state != CHANNEL_OPENED_STATE) {
+		ret = -EIO;
+		goto cpu_store_unlock;
+	}
+
+	origin_cpu = channel->target_cpu;
+	if (target_cpu == origin_cpu)
+		goto cpu_store_unlock;
+
+	if (vmbus_send_modifychannel(channel->offermsg.child_relid,
+				     hv_cpu_number_to_vp_number(target_cpu))) {
+		ret = -EIO;
+		goto cpu_store_unlock;
+	}
+
+	/*
+	 * Warning.  At this point, there is *no* guarantee that the host will
+	 * have successfully processed the vmbus_send_modifychannel() request.
+	 * See the header comment of vmbus_send_modifychannel() for more info.
+	 *
+	 * Lags in the processing of the above vmbus_send_modifychannel() can
+	 * result in missed interrupts if the "old" target CPU is taken offline
+	 * before Hyper-V starts sending interrupts to the "new" target CPU.
+	 * But apart from this offlining scenario, the code tolerates such
+	 * lags.  It will function correctly even if a channel interrupt comes
+	 * in on a CPU that is different from the channel target_cpu value.
+	 */
+
+	channel->target_cpu = target_cpu;
+
+	/* See init_vp_index(). */
+	if (hv_is_perf_channel(channel))
+		hv_update_alloced_cpus(origin_cpu, target_cpu);
+
+	/* Currently set only for storvsc channels. */
+	if (channel->change_target_cpu_callback) {
+		(*channel->change_target_cpu_callback)(channel,
+				origin_cpu, target_cpu);
+	}
+
+cpu_store_unlock:
+	mutex_unlock(&vmbus_connection.channel_mutex);
+	cpus_read_unlock();
+	return ret;
+}
+static VMBUS_CHAN_ATTR(cpu, 0644, target_cpu_show, target_cpu_store);
+
+static ssize_t channel_pending_show(struct vmbus_channel *channel,
+				    char *buf)
+{
+	return sprintf(buf, "%d\n",
+		       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\n",
+		       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\n", 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\n", 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\n",
+		       (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\n",
+		       (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\n",
+		       (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\n",
+		       (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\n", 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\n",
+		       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) {
+		kobject_put(kobj);
+		return ret;
+	}
+
+	ret = sysfs_create_group(kobj, &vmbus_chan_group);
+
+	if (ret) {
+		/*
+		 * The calling functions' error handling paths will cleanup the
+		 * empty channel directory.
+		 */
+		kobject_put(kobj);
+		dev_err(device, "Unable to set up channel sysfs files\n");
+		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\n");
+		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);
+
+	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\n");
+		put_device(&child_device_obj->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;
+	}
+	hv_debug_add_dev_dir(child_device_obj);
+
+	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\n",
+		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;
+	struct resource r;
+
+	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;
+
+	/*
+	 * The IRQ information is needed only on ARM64, which Hyper-V
+	 * sets up in the extended format. IRQ information is present
+	 * on x86/x64 in the non-extended format but it is not used by
+	 * Linux. So don't bother checking for the non-extended format.
+	 */
+	case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
+		if (!acpi_dev_resource_interrupt(res, 0, &r)) {
+			pr_err("Unable to parse Hyper-V ACPI interrupt\n");
+			return AE_ERROR;
+		}
+		/* ARM64 INTID for VMbus */
+		vmbus_interrupt = res->data.extended_irq.interrupts[0];
+		/* Linux IRQ number */
+		vmbus_irq = r.start;
+		return AE_OK;
+
+	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, end;
+	const char *dev_n = dev_name(&device_obj->device);
+	int retval;
+
+	retval = -ENXIO;
+	mutex_lock(&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) {
+			end = start + size - 1;
+
+			/* Skip the whole fb_mmio region if not fb_overlap_ok */
+			if (!fb_overlap_ok && fb_mmio &&
+			    (((start >= fb_mmio->start) && (start <= fb_mmio->end)) ||
+			     ((end >= fb_mmio->start) && (end <= fb_mmio->end))))
+				continue;
+
+			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:
+	mutex_unlock(&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;
+
+	mutex_lock(&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);
+	mutex_unlock(&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;
+
+	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);
+
+	if (atomic_read(&vmbus_connection.nr_chan_fixup_on_resume) != 0) {
+		pr_err("Can not suspend due to a previous failed resuming\n");
+		return -EBUSY;
+	}
+
+	mutex_lock(&vmbus_connection.channel_mutex);
+
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		/*
+		 * Remove the channel from the array of channels and invalidate
+		 * the channel's relid.  Upon resume, vmbus_onoffer() will fix
+		 * up the relid (and other fields, if necessary) and add the
+		 * channel back to the array.
+		 */
+		vmbus_channel_unmap_relid(channel);
+		channel->offermsg.child_relid = INVALID_RELID;
+
+		if (is_hvsock_channel(channel)) {
+			if (!channel->rescind) {
+				pr_err("hv_sock channel not rescinded!\n");
+				WARN_ON_ONCE(1);
+			}
+			continue;
+		}
+
+		list_for_each_entry(sc, &channel->sc_list, sc_list) {
+			pr_err("Sub-channel not deleted!\n");
+			WARN_ON_ONCE(1);
+		}
+
+		atomic_inc(&vmbus_connection.nr_chan_fixup_on_resume);
+	}
+
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
+	vmbus_initiate_unload(false);
+
+	/* 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) {
+		pr_err("Invalid proto version = 0x%x\n", 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();
+
+	if (wait_for_completion_timeout(
+		&vmbus_connection.ready_for_resume_event, 10 * HZ) == 0)
+		pr_err("Some vmbus device is missing after suspending?\n");
+
+	/* Reset the event for the next suspend. */
+	reinit_completion(&vmbus_connection.ready_for_suspend_event);
+
+	return 0;
+}
+#else
+#define vmbus_bus_suspend NULL
+#define vmbus_bus_resume NULL
+#endif /* CONFIG_PM_SLEEP */
+
+static const struct acpi_device_id vmbus_acpi_device_ids[] = {
+	{"VMBUS", 0},
+	{"VMBus", 0},
+	{"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, vmbus_acpi_device_ids);
+
+/*
+ * Note: we must use the "no_irq" ops, otherwise hibernation can not work with
+ * PCI device assignment, because "pci_dev_pm_ops" uses the "noirq" ops: in
+ * the resume path, the pci "noirq" restore op runs before "non-noirq" op (see
+ * resume_target_kernel() -> dpm_resume_start(), and hibernation_restore() ->
+ * dpm_resume_end()). This means vmbus_bus_resume() and the pci-hyperv's
+ * resume callback must also run via the "noirq" ops.
+ *
+ * Set suspend_noirq/resume_noirq to NULL for Suspend-to-Idle: see the comment
+ * earlier in this file before vmbus_pm.
+ */
+
+static const struct dev_pm_ops vmbus_bus_pm = {
+	.suspend_noirq	= NULL,
+	.resume_noirq	= NULL,
+	.freeze_noirq	= vmbus_bus_suspend,
+	.thaw_noirq	= vmbus_bus_resume,
+	.poweroff_noirq	= vmbus_bus_suspend,
+	.restore_noirq	= vmbus_bus_resume
+};
+
+static struct acpi_driver vmbus_acpi_driver = {
+	.name = "vmbus",
+	.ids = vmbus_acpi_device_ids,
+	.ops = {
+		.add = vmbus_acpi_add,
+		.remove = vmbus_acpi_remove,
+	},
+	.drv.pm = &vmbus_bus_pm,
+};
+
+static void hv_kexec_handler(void)
+{
+	hv_stimer_global_cleanup();
+	vmbus_initiate_unload(false);
+	/* Make sure conn_state is set as hv_synic_cleanup checks for it */
+	mb();
+	cpuhp_remove_state(hyperv_cpuhp_online);
+};
+
+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,
+	 * doing the cleanup for current CPU only. This should be sufficient
+	 * for kdump.
+	 */
+	cpu = smp_processor_id();
+	hv_stimer_cleanup(cpu);
+	hv_synic_disable_regs(cpu);
+};
+
+static int hv_synic_suspend(void)
+{
+	/*
+	 * When we reach here, all the non-boot CPUs have been offlined.
+	 * If we're in a legacy configuration where stimer Direct Mode is
+	 * not enabled, the stimers on the non-boot CPUs have been unbound
+	 * in hv_synic_cleanup() -> hv_stimer_legacy_cleanup() ->
+	 * hv_stimer_cleanup() -> clockevents_unbind_device().
+	 *
+	 * hv_synic_suspend() only runs on CPU0 with interrupts disabled.
+	 * Here we do not call hv_stimer_legacy_cleanup() on CPU0 because:
+	 * 1) it's unnecessary as interrupts remain disabled between
+	 * syscore_suspend() and syscore_resume(): see create_image() and
+	 * resume_target_kernel()
+	 * 2) the stimer on CPU0 is automatically disabled later by
+	 * syscore_suspend() -> timekeeping_suspend() -> tick_suspend() -> ...
+	 * -> clockevents_shutdown() -> ... -> hv_ce_shutdown()
+	 * 3) a warning would be triggered if we call
+	 * clockevents_unbind_device(), which may sleep, in an
+	 * interrupts-disabled context.
+	 */
+
+	hv_synic_disable_regs(0);
+
+	return 0;
+}
+
+static void hv_synic_resume(void)
+{
+	hv_synic_enable_regs(0);
+
+	/*
+	 * Note: we don't need to call hv_stimer_init(0), because the timer
+	 * on CPU0 is not unbound in hv_synic_suspend(), and the timer is
+	 * automatically re-enabled in timekeeping_resume().
+	 */
+}
+
+/* The callbacks run only on CPU0, with irqs_disabled. */
+static struct syscore_ops hv_synic_syscore_ops = {
+	.suspend = hv_synic_suspend,
+	.resume = hv_synic_resume,
+};
+
+static int __init hv_acpi_init(void)
+{
+	int ret, t;
+
+	if (!hv_is_hyperv_initialized())
+		return -ENODEV;
+
+	init_completion(&probe_event);
+
+	/*
+	 * Get ACPI resources first.
+	 */
+	ret = acpi_bus_register_driver(&vmbus_acpi_driver);
+
+	if (ret)
+		return ret;
+
+	t = wait_for_completion_timeout(&probe_event, 5*HZ);
+	if (t == 0) {
+		ret = -ETIMEDOUT;
+		goto cleanup;
+	}
+	hv_debug_init();
+
+	ret = vmbus_bus_init();
+	if (ret)
+		goto cleanup;
+
+	hv_setup_kexec_handler(hv_kexec_handler);
+	hv_setup_crash_handler(hv_crash_handler);
+
+	register_syscore_ops(&hv_synic_syscore_ops);
+
+	return 0;
+
+cleanup:
+	acpi_bus_unregister_driver(&vmbus_acpi_driver);
+	hv_acpi_dev = NULL;
+	return ret;
+}
+
+static void __exit vmbus_exit(void)
+{
+	int cpu;
+
+	unregister_syscore_ops(&hv_synic_syscore_ops);
+
+	hv_remove_kexec_handler();
+	hv_remove_crash_handler();
+	vmbus_connection.conn_state = DISCONNECTED;
+	hv_stimer_global_cleanup();
+	vmbus_disconnect();
+	hv_remove_vmbus_irq();
+	for_each_online_cpu(cpu) {
+		struct hv_per_cpu_context *hv_cpu
+			= per_cpu_ptr(hv_context.cpu_context, cpu);
+
+		tasklet_kill(&hv_cpu->msg_dpc);
+	}
+	hv_debug_rm_all_dir();
+
+	vmbus_free_channels();
+	kfree(vmbus_connection.channels);
+
+	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
+		kmsg_dump_unregister(&hv_kmsg_dumper);
+		unregister_die_notifier(&hyperv_die_block);
+	}
+
+	/*
+	 * The panic notifier is always registered, hence we should
+	 * also unconditionally unregister it here as well.
+	 */
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &hyperv_panic_block);
+
+	free_page((unsigned long)hv_panic_page);
+	unregister_sysctl_table(hv_ctl_table_hdr);
+	hv_ctl_table_hdr = NULL;
+	bus_unregister(&hv_bus);
+
+	cpuhp_remove_state(hyperv_cpuhp_online);
+	hv_synic_free();
+	acpi_bus_unregister_driver(&vmbus_acpi_driver);
+}
+
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Microsoft Hyper-V VMBus Driver");
+
+subsys_initcall(hv_acpi_init);
+module_exit(vmbus_exit);