Adding upstream version 4.19.249.upstream/4.19.249

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

1 files changed, 900 insertions, 0 deletions

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
new file mode 100644
index 000000000..5e515533e
--- /dev/null
+++ b/drivers/hv/channel.c
@@ -0,0 +1,900 @@
+/*
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/hyperv.h>
+#include <linux/uio.h>
+#include <linux/interrupt.h>
+#include <asm/page.h>
+
+#include "hyperv_vmbus.h"
+
+#define NUM_PAGES_SPANNED(addr, len) \
+((PAGE_ALIGN(addr + len) >> PAGE_SHIFT) - (addr >> PAGE_SHIFT))
+
+static unsigned long virt_to_hvpfn(void *addr)
+{
+	phys_addr_t paddr;
+
+	if (is_vmalloc_addr(addr))
+		paddr = page_to_phys(vmalloc_to_page(addr)) +
+					 offset_in_page(addr);
+	else
+		paddr = __pa(addr);
+
+	return  paddr >> PAGE_SHIFT;
+}
+
+/*
+ * vmbus_setevent- Trigger an event notification on the specified
+ * channel.
+ */
+void vmbus_setevent(struct vmbus_channel *channel)
+{
+	struct hv_monitor_page *monitorpage;
+
+	trace_vmbus_setevent(channel);
+
+	/*
+	 * For channels marked as in "low latency" mode
+	 * bypass the monitor page mechanism.
+	 */
+	if (channel->offermsg.monitor_allocated && !channel->low_latency) {
+		vmbus_send_interrupt(channel->offermsg.child_relid);
+
+		/* Get the child to parent monitor page */
+		monitorpage = vmbus_connection.monitor_pages[1];
+
+		sync_set_bit(channel->monitor_bit,
+			(unsigned long *)&monitorpage->trigger_group
+					[channel->monitor_grp].pending);
+
+	} else {
+		vmbus_set_event(channel);
+	}
+}
+EXPORT_SYMBOL_GPL(vmbus_setevent);
+
+/*
+ * vmbus_open - Open the specified channel.
+ */
+int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size,
+		     u32 recv_ringbuffer_size, void *userdata, u32 userdatalen,
+		     void (*onchannelcallback)(void *context), void *context)
+{
+	struct vmbus_channel_open_channel *open_msg;
+	struct vmbus_channel_msginfo *open_info = NULL;
+	unsigned long flags;
+	int ret, err = 0;
+	struct page *page;
+	unsigned int order;
+
+	if (send_ringbuffer_size % PAGE_SIZE ||
+	    recv_ringbuffer_size % PAGE_SIZE)
+		return -EINVAL;
+
+	order = get_order(send_ringbuffer_size + recv_ringbuffer_size);
+
+	spin_lock_irqsave(&newchannel->lock, flags);
+	if (newchannel->state == CHANNEL_OPEN_STATE) {
+		newchannel->state = CHANNEL_OPENING_STATE;
+	} else {
+		spin_unlock_irqrestore(&newchannel->lock, flags);
+		return -EINVAL;
+	}
+	spin_unlock_irqrestore(&newchannel->lock, flags);
+
+	newchannel->onchannel_callback = onchannelcallback;
+	newchannel->channel_callback_context = context;
+
+	/* Allocate the ring buffer */
+	page = alloc_pages_node(cpu_to_node(newchannel->target_cpu),
+				GFP_KERNEL|__GFP_ZERO, order);
+
+	if (!page)
+		page = alloc_pages(GFP_KERNEL|__GFP_ZERO, order);
+
+	if (!page) {
+		err = -ENOMEM;
+		goto error_set_chnstate;
+	}
+
+	newchannel->ringbuffer_page = page;
+	newchannel->ringbuffer_pagecount = (send_ringbuffer_size +
+					   recv_ringbuffer_size) >> PAGE_SHIFT;
+
+	ret = hv_ringbuffer_init(&newchannel->outbound, page,
+				 send_ringbuffer_size >> PAGE_SHIFT);
+
+	if (ret != 0) {
+		err = ret;
+		goto error_free_pages;
+	}
+
+	ret = hv_ringbuffer_init(&newchannel->inbound,
+				 &page[send_ringbuffer_size >> PAGE_SHIFT],
+				 recv_ringbuffer_size >> PAGE_SHIFT);
+	if (ret != 0) {
+		err = ret;
+		goto error_free_pages;
+	}
+
+
+	/* Establish the gpadl for the ring buffer */
+	newchannel->ringbuffer_gpadlhandle = 0;
+
+	ret = vmbus_establish_gpadl(newchannel,
+				    page_address(page),
+				    send_ringbuffer_size +
+				    recv_ringbuffer_size,
+				    &newchannel->ringbuffer_gpadlhandle);
+
+	if (ret != 0) {
+		err = ret;
+		goto error_free_pages;
+	}
+
+	/* Create and init the channel open message */
+	open_info = kmalloc(sizeof(*open_info) +
+			   sizeof(struct vmbus_channel_open_channel),
+			   GFP_KERNEL);
+	if (!open_info) {
+		err = -ENOMEM;
+		goto error_free_gpadl;
+	}
+
+	init_completion(&open_info->waitevent);
+	open_info->waiting_channel = newchannel;
+
+	open_msg = (struct vmbus_channel_open_channel *)open_info->msg;
+	open_msg->header.msgtype = CHANNELMSG_OPENCHANNEL;
+	open_msg->openid = newchannel->offermsg.child_relid;
+	open_msg->child_relid = newchannel->offermsg.child_relid;
+	open_msg->ringbuffer_gpadlhandle = newchannel->ringbuffer_gpadlhandle;
+	open_msg->downstream_ringbuffer_pageoffset = send_ringbuffer_size >>
+						  PAGE_SHIFT;
+	open_msg->target_vp = newchannel->target_vp;
+
+	if (userdatalen > MAX_USER_DEFINED_BYTES) {
+		err = -EINVAL;
+		goto error_free_gpadl;
+	}
+
+	if (userdatalen)
+		memcpy(open_msg->userdata, userdata, userdatalen);
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&open_info->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (newchannel->rescind) {
+		err = -ENODEV;
+		goto error_free_gpadl;
+	}
+
+	ret = vmbus_post_msg(open_msg,
+			     sizeof(struct vmbus_channel_open_channel), true);
+
+	trace_vmbus_open(open_msg, ret);
+
+	if (ret != 0) {
+		err = ret;
+		goto error_clean_msglist;
+	}
+
+	wait_for_completion(&open_info->waitevent);
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&open_info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (newchannel->rescind) {
+		err = -ENODEV;
+		goto error_free_gpadl;
+	}
+
+	if (open_info->response.open_result.status) {
+		err = -EAGAIN;
+		goto error_free_gpadl;
+	}
+
+	newchannel->state = CHANNEL_OPENED_STATE;
+	kfree(open_info);
+	return 0;
+
+error_clean_msglist:
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&open_info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+error_free_gpadl:
+	vmbus_teardown_gpadl(newchannel, newchannel->ringbuffer_gpadlhandle);
+	kfree(open_info);
+error_free_pages:
+	hv_ringbuffer_cleanup(&newchannel->outbound);
+	hv_ringbuffer_cleanup(&newchannel->inbound);
+	__free_pages(page, order);
+error_set_chnstate:
+	newchannel->state = CHANNEL_OPEN_STATE;
+	return err;
+}
+EXPORT_SYMBOL_GPL(vmbus_open);
+
+/* Used for Hyper-V Socket: a guest client's connect() to the host */
+int vmbus_send_tl_connect_request(const uuid_le *shv_guest_servie_id,
+				  const uuid_le *shv_host_servie_id)
+{
+	struct vmbus_channel_tl_connect_request conn_msg;
+	int ret;
+
+	memset(&conn_msg, 0, sizeof(conn_msg));
+	conn_msg.header.msgtype = CHANNELMSG_TL_CONNECT_REQUEST;
+	conn_msg.guest_endpoint_id = *shv_guest_servie_id;
+	conn_msg.host_service_id = *shv_host_servie_id;
+
+	ret = vmbus_post_msg(&conn_msg, sizeof(conn_msg), true);
+
+	trace_vmbus_send_tl_connect_request(&conn_msg, ret);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_send_tl_connect_request);
+
+/*
+ * create_gpadl_header - Creates a gpadl for the specified buffer
+ */
+static int create_gpadl_header(void *kbuffer, u32 size,
+			       struct vmbus_channel_msginfo **msginfo)
+{
+	int i;
+	int pagecount;
+	struct vmbus_channel_gpadl_header *gpadl_header;
+	struct vmbus_channel_gpadl_body *gpadl_body;
+	struct vmbus_channel_msginfo *msgheader;
+	struct vmbus_channel_msginfo *msgbody = NULL;
+	u32 msgsize;
+
+	int pfnsum, pfncount, pfnleft, pfncurr, pfnsize;
+
+	pagecount = size >> PAGE_SHIFT;
+
+	/* do we need a gpadl body msg */
+	pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
+		  sizeof(struct vmbus_channel_gpadl_header) -
+		  sizeof(struct gpa_range);
+	pfncount = pfnsize / sizeof(u64);
+
+	if (pagecount > pfncount) {
+		/* we need a gpadl body */
+		/* fill in the header */
+		msgsize = sizeof(struct vmbus_channel_msginfo) +
+			  sizeof(struct vmbus_channel_gpadl_header) +
+			  sizeof(struct gpa_range) + pfncount * sizeof(u64);
+		msgheader =  kzalloc(msgsize, GFP_KERNEL);
+		if (!msgheader)
+			goto nomem;
+
+		INIT_LIST_HEAD(&msgheader->submsglist);
+		msgheader->msgsize = msgsize;
+
+		gpadl_header = (struct vmbus_channel_gpadl_header *)
+			msgheader->msg;
+		gpadl_header->rangecount = 1;
+		gpadl_header->range_buflen = sizeof(struct gpa_range) +
+					 pagecount * sizeof(u64);
+		gpadl_header->range[0].byte_offset = 0;
+		gpadl_header->range[0].byte_count = size;
+		for (i = 0; i < pfncount; i++)
+			gpadl_header->range[0].pfn_array[i] = virt_to_hvpfn(
+				kbuffer + PAGE_SIZE * i);
+		*msginfo = msgheader;
+
+		pfnsum = pfncount;
+		pfnleft = pagecount - pfncount;
+
+		/* how many pfns can we fit */
+		pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
+			  sizeof(struct vmbus_channel_gpadl_body);
+		pfncount = pfnsize / sizeof(u64);
+
+		/* fill in the body */
+		while (pfnleft) {
+			if (pfnleft > pfncount)
+				pfncurr = pfncount;
+			else
+				pfncurr = pfnleft;
+
+			msgsize = sizeof(struct vmbus_channel_msginfo) +
+				  sizeof(struct vmbus_channel_gpadl_body) +
+				  pfncurr * sizeof(u64);
+			msgbody = kzalloc(msgsize, GFP_KERNEL);
+
+			if (!msgbody) {
+				struct vmbus_channel_msginfo *pos = NULL;
+				struct vmbus_channel_msginfo *tmp = NULL;
+				/*
+				 * Free up all the allocated messages.
+				 */
+				list_for_each_entry_safe(pos, tmp,
+					&msgheader->submsglist,
+					msglistentry) {
+
+					list_del(&pos->msglistentry);
+					kfree(pos);
+				}
+
+				goto nomem;
+			}
+
+			msgbody->msgsize = msgsize;
+			gpadl_body =
+				(struct vmbus_channel_gpadl_body *)msgbody->msg;
+
+			/*
+			 * Gpadl is u32 and we are using a pointer which could
+			 * be 64-bit
+			 * This is governed by the guest/host protocol and
+			 * so the hypervisor guarantees that this is ok.
+			 */
+			for (i = 0; i < pfncurr; i++)
+				gpadl_body->pfn[i] = virt_to_hvpfn(
+					kbuffer + PAGE_SIZE * (pfnsum + i));
+
+			/* add to msg header */
+			list_add_tail(&msgbody->msglistentry,
+				      &msgheader->submsglist);
+			pfnsum += pfncurr;
+			pfnleft -= pfncurr;
+		}
+	} else {
+		/* everything fits in a header */
+		msgsize = sizeof(struct vmbus_channel_msginfo) +
+			  sizeof(struct vmbus_channel_gpadl_header) +
+			  sizeof(struct gpa_range) + pagecount * sizeof(u64);
+		msgheader = kzalloc(msgsize, GFP_KERNEL);
+		if (msgheader == NULL)
+			goto nomem;
+
+		INIT_LIST_HEAD(&msgheader->submsglist);
+		msgheader->msgsize = msgsize;
+
+		gpadl_header = (struct vmbus_channel_gpadl_header *)
+			msgheader->msg;
+		gpadl_header->rangecount = 1;
+		gpadl_header->range_buflen = sizeof(struct gpa_range) +
+					 pagecount * sizeof(u64);
+		gpadl_header->range[0].byte_offset = 0;
+		gpadl_header->range[0].byte_count = size;
+		for (i = 0; i < pagecount; i++)
+			gpadl_header->range[0].pfn_array[i] = virt_to_hvpfn(
+				kbuffer + PAGE_SIZE * i);
+
+		*msginfo = msgheader;
+	}
+
+	return 0;
+nomem:
+	kfree(msgheader);
+	kfree(msgbody);
+	return -ENOMEM;
+}
+
+/*
+ * vmbus_establish_gpadl - Establish a GPADL for the specified buffer
+ *
+ * @channel: a channel
+ * @kbuffer: from kmalloc or vmalloc
+ * @size: page-size multiple
+ * @gpadl_handle: some funky thing
+ */
+int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
+			       u32 size, u32 *gpadl_handle)
+{
+	struct vmbus_channel_gpadl_header *gpadlmsg;
+	struct vmbus_channel_gpadl_body *gpadl_body;
+	struct vmbus_channel_msginfo *msginfo = NULL;
+	struct vmbus_channel_msginfo *submsginfo, *tmp;
+	struct list_head *curr;
+	u32 next_gpadl_handle;
+	unsigned long flags;
+	int ret = 0;
+
+	next_gpadl_handle =
+		(atomic_inc_return(&vmbus_connection.next_gpadl_handle) - 1);
+
+	ret = create_gpadl_header(kbuffer, size, &msginfo);
+	if (ret)
+		return ret;
+
+	init_completion(&msginfo->waitevent);
+	msginfo->waiting_channel = channel;
+
+	gpadlmsg = (struct vmbus_channel_gpadl_header *)msginfo->msg;
+	gpadlmsg->header.msgtype = CHANNELMSG_GPADL_HEADER;
+	gpadlmsg->child_relid = channel->offermsg.child_relid;
+	gpadlmsg->gpadl = next_gpadl_handle;
+
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&msginfo->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (channel->rescind) {
+		ret = -ENODEV;
+		goto cleanup;
+	}
+
+	ret = vmbus_post_msg(gpadlmsg, msginfo->msgsize -
+			     sizeof(*msginfo), true);
+
+	trace_vmbus_establish_gpadl_header(gpadlmsg, ret);
+
+	if (ret != 0)
+		goto cleanup;
+
+	list_for_each(curr, &msginfo->submsglist) {
+		submsginfo = (struct vmbus_channel_msginfo *)curr;
+		gpadl_body =
+			(struct vmbus_channel_gpadl_body *)submsginfo->msg;
+
+		gpadl_body->header.msgtype =
+			CHANNELMSG_GPADL_BODY;
+		gpadl_body->gpadl = next_gpadl_handle;
+
+		ret = vmbus_post_msg(gpadl_body,
+				     submsginfo->msgsize - sizeof(*submsginfo),
+				     true);
+
+		trace_vmbus_establish_gpadl_body(gpadl_body, ret);
+
+		if (ret != 0)
+			goto cleanup;
+
+	}
+	wait_for_completion(&msginfo->waitevent);
+
+	if (msginfo->response.gpadl_created.creation_status != 0) {
+		pr_err("Failed to establish GPADL: err = 0x%x\n",
+		       msginfo->response.gpadl_created.creation_status);
+
+		ret = -EDQUOT;
+		goto cleanup;
+	}
+
+	if (channel->rescind) {
+		ret = -ENODEV;
+		goto cleanup;
+	}
+
+	/* At this point, we received the gpadl created msg */
+	*gpadl_handle = gpadlmsg->gpadl;
+
+cleanup:
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&msginfo->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+	list_for_each_entry_safe(submsginfo, tmp, &msginfo->submsglist,
+				 msglistentry) {
+		kfree(submsginfo);
+	}
+
+	kfree(msginfo);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_establish_gpadl);
+
+/*
+ * vmbus_teardown_gpadl -Teardown the specified GPADL handle
+ */
+int vmbus_teardown_gpadl(struct vmbus_channel *channel, u32 gpadl_handle)
+{
+	struct vmbus_channel_gpadl_teardown *msg;
+	struct vmbus_channel_msginfo *info;
+	unsigned long flags;
+	int ret;
+
+	info = kmalloc(sizeof(*info) +
+		       sizeof(struct vmbus_channel_gpadl_teardown), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	init_completion(&info->waitevent);
+	info->waiting_channel = channel;
+
+	msg = (struct vmbus_channel_gpadl_teardown *)info->msg;
+
+	msg->header.msgtype = CHANNELMSG_GPADL_TEARDOWN;
+	msg->child_relid = channel->offermsg.child_relid;
+	msg->gpadl = gpadl_handle;
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&info->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (channel->rescind)
+		goto post_msg_err;
+
+	ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_gpadl_teardown),
+			     true);
+
+	trace_vmbus_teardown_gpadl(msg, ret);
+
+	if (ret)
+		goto post_msg_err;
+
+	wait_for_completion(&info->waitevent);
+
+post_msg_err:
+	/*
+	 * If the channel has been rescinded;
+	 * we will be awakened by the rescind
+	 * handler; set the error code to zero so we don't leak memory.
+	 */
+	if (channel->rescind)
+		ret = 0;
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	kfree(info);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_teardown_gpadl);
+
+static void reset_channel_cb(void *arg)
+{
+	struct vmbus_channel *channel = arg;
+
+	channel->onchannel_callback = NULL;
+}
+
+void vmbus_reset_channel_cb(struct vmbus_channel *channel)
+{
+	/*
+	 * vmbus_on_event(), running in the per-channel tasklet, can race
+	 * with vmbus_close_internal() in the case of SMP guest, e.g., when
+	 * the former is accessing channel->inbound.ring_buffer, the latter
+	 * could be freeing the ring_buffer pages, so here we must stop it
+	 * first.
+	 */
+	tasklet_disable(&channel->callback_event);
+
+	channel->sc_creation_callback = NULL;
+
+	/* Stop the callback asap */
+	if (channel->target_cpu != get_cpu()) {
+		put_cpu();
+		smp_call_function_single(channel->target_cpu, reset_channel_cb,
+					 channel, true);
+	} else {
+		reset_channel_cb(channel);
+		put_cpu();
+	}
+
+	/* Re-enable tasklet for use on re-open */
+	tasklet_enable(&channel->callback_event);
+}
+
+static int vmbus_close_internal(struct vmbus_channel *channel)
+{
+	struct vmbus_channel_close_channel *msg;
+	int ret;
+
+	vmbus_reset_channel_cb(channel);
+
+	/*
+	 * In case a device driver's probe() fails (e.g.,
+	 * util_probe() -> vmbus_open() returns -ENOMEM) and the device is
+	 * rescinded later (e.g., we dynamically disable an Integrated Service
+	 * in Hyper-V Manager), the driver's remove() invokes vmbus_close():
+	 * here we should skip most of the below cleanup work.
+	 */
+	if (channel->state != CHANNEL_OPENED_STATE) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	channel->state = CHANNEL_OPEN_STATE;
+
+	/* Send a closing message */
+
+	msg = &channel->close_msg.msg;
+
+	msg->header.msgtype = CHANNELMSG_CLOSECHANNEL;
+	msg->child_relid = channel->offermsg.child_relid;
+
+	ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_close_channel),
+			     true);
+
+	trace_vmbus_close_internal(msg, ret);
+
+	if (ret) {
+		pr_err("Close failed: close post msg return is %d\n", ret);
+		/*
+		 * If we failed to post the close msg,
+		 * it is perhaps better to leak memory.
+		 */
+		goto out;
+	}
+
+	/* Tear down the gpadl for the channel's ring buffer */
+	if (channel->ringbuffer_gpadlhandle) {
+		ret = vmbus_teardown_gpadl(channel,
+					   channel->ringbuffer_gpadlhandle);
+		if (ret) {
+			pr_err("Close failed: teardown gpadl return %d\n", ret);
+			/*
+			 * If we failed to teardown gpadl,
+			 * it is perhaps better to leak memory.
+			 */
+			goto out;
+		}
+	}
+
+	/* Cleanup the ring buffers for this channel */
+	hv_ringbuffer_cleanup(&channel->outbound);
+	hv_ringbuffer_cleanup(&channel->inbound);
+
+	__free_pages(channel->ringbuffer_page,
+		     get_order(channel->ringbuffer_pagecount << PAGE_SHIFT));
+
+out:
+	return ret;
+}
+
+/*
+ * vmbus_close - Close the specified channel
+ */
+void vmbus_close(struct vmbus_channel *channel)
+{
+	struct list_head *cur, *tmp;
+	struct vmbus_channel *cur_channel;
+
+	if (channel->primary_channel != NULL) {
+		/*
+		 * We will only close sub-channels when
+		 * the primary is closed.
+		 */
+		return;
+	}
+	/*
+	 * Close all the sub-channels first and then close the
+	 * primary channel.
+	 */
+	list_for_each_safe(cur, tmp, &channel->sc_list) {
+		cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
+		if (cur_channel->rescind) {
+			wait_for_completion(&cur_channel->rescind_event);
+			mutex_lock(&vmbus_connection.channel_mutex);
+			vmbus_close_internal(cur_channel);
+			hv_process_channel_removal(
+					   cur_channel->offermsg.child_relid);
+		} else {
+			mutex_lock(&vmbus_connection.channel_mutex);
+			vmbus_close_internal(cur_channel);
+		}
+		mutex_unlock(&vmbus_connection.channel_mutex);
+	}
+	/*
+	 * Now close the primary.
+	 */
+	mutex_lock(&vmbus_connection.channel_mutex);
+	vmbus_close_internal(channel);
+	mutex_unlock(&vmbus_connection.channel_mutex);
+}
+EXPORT_SYMBOL_GPL(vmbus_close);
+
+/**
+ * vmbus_sendpacket() - Send the specified buffer on the given channel
+ * @channel: Pointer to vmbus_channel structure.
+ * @buffer: Pointer to the buffer you want to receive the data into.
+ * @bufferlen: Maximum size of what the the buffer will hold
+ * @requestid: Identifier of the request
+ * @type: Type of packet that is being send e.g. negotiate, time
+ * packet etc.
+ *
+ * Sends data in @buffer directly to hyper-v via the vmbus
+ * This will send the data unparsed to hyper-v.
+ *
+ * Mainly used by Hyper-V drivers.
+ */
+int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
+			   u32 bufferlen, u64 requestid,
+			   enum vmbus_packet_type type, u32 flags)
+{
+	struct vmpacket_descriptor desc;
+	u32 packetlen = sizeof(struct vmpacket_descriptor) + bufferlen;
+	u32 packetlen_aligned = ALIGN(packetlen, sizeof(u64));
+	struct kvec bufferlist[3];
+	u64 aligned_data = 0;
+	int num_vecs = ((bufferlen != 0) ? 3 : 1);
+
+
+	/* Setup the descriptor */
+	desc.type = type; /* VmbusPacketTypeDataInBand; */
+	desc.flags = flags; /* VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED; */
+	/* in 8-bytes granularity */
+	desc.offset8 = sizeof(struct vmpacket_descriptor) >> 3;
+	desc.len8 = (u16)(packetlen_aligned >> 3);
+	desc.trans_id = requestid;
+
+	bufferlist[0].iov_base = &desc;
+	bufferlist[0].iov_len = sizeof(struct vmpacket_descriptor);
+	bufferlist[1].iov_base = buffer;
+	bufferlist[1].iov_len = bufferlen;
+	bufferlist[2].iov_base = &aligned_data;
+	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
+
+	return hv_ringbuffer_write(channel, bufferlist, num_vecs);
+}
+EXPORT_SYMBOL(vmbus_sendpacket);
+
+/*
+ * vmbus_sendpacket_pagebuffer - Send a range of single-page buffer
+ * packets using a GPADL Direct packet type. This interface allows you
+ * to control notifying the host. This will be useful for sending
+ * batched data. Also the sender can control the send flags
+ * explicitly.
+ */
+int vmbus_sendpacket_pagebuffer(struct vmbus_channel *channel,
+				struct hv_page_buffer pagebuffers[],
+				u32 pagecount, void *buffer, u32 bufferlen,
+				u64 requestid)
+{
+	int i;
+	struct vmbus_channel_packet_page_buffer desc;
+	u32 descsize;
+	u32 packetlen;
+	u32 packetlen_aligned;
+	struct kvec bufferlist[3];
+	u64 aligned_data = 0;
+
+	if (pagecount > MAX_PAGE_BUFFER_COUNT)
+		return -EINVAL;
+
+	/*
+	 * Adjust the size down since vmbus_channel_packet_page_buffer is the
+	 * largest size we support
+	 */
+	descsize = sizeof(struct vmbus_channel_packet_page_buffer) -
+			  ((MAX_PAGE_BUFFER_COUNT - pagecount) *
+			  sizeof(struct hv_page_buffer));
+	packetlen = descsize + bufferlen;
+	packetlen_aligned = ALIGN(packetlen, sizeof(u64));
+
+	/* Setup the descriptor */
+	desc.type = VM_PKT_DATA_USING_GPA_DIRECT;
+	desc.flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
+	desc.dataoffset8 = descsize >> 3; /* in 8-bytes granularity */
+	desc.length8 = (u16)(packetlen_aligned >> 3);
+	desc.transactionid = requestid;
+	desc.reserved = 0;
+	desc.rangecount = pagecount;
+
+	for (i = 0; i < pagecount; i++) {
+		desc.range[i].len = pagebuffers[i].len;
+		desc.range[i].offset = pagebuffers[i].offset;
+		desc.range[i].pfn	 = pagebuffers[i].pfn;
+	}
+
+	bufferlist[0].iov_base = &desc;
+	bufferlist[0].iov_len = descsize;
+	bufferlist[1].iov_base = buffer;
+	bufferlist[1].iov_len = bufferlen;
+	bufferlist[2].iov_base = &aligned_data;
+	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
+
+	return hv_ringbuffer_write(channel, bufferlist, 3);
+}
+EXPORT_SYMBOL_GPL(vmbus_sendpacket_pagebuffer);
+
+/*
+ * vmbus_sendpacket_multipagebuffer - Send a multi-page buffer packet
+ * using a GPADL Direct packet type.
+ * The buffer includes the vmbus descriptor.
+ */
+int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
+			      struct vmbus_packet_mpb_array *desc,
+			      u32 desc_size,
+			      void *buffer, u32 bufferlen, u64 requestid)
+{
+	u32 packetlen;
+	u32 packetlen_aligned;
+	struct kvec bufferlist[3];
+	u64 aligned_data = 0;
+
+	packetlen = desc_size + bufferlen;
+	packetlen_aligned = ALIGN(packetlen, sizeof(u64));
+
+	/* Setup the descriptor */
+	desc->type = VM_PKT_DATA_USING_GPA_DIRECT;
+	desc->flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
+	desc->dataoffset8 = desc_size >> 3; /* in 8-bytes granularity */
+	desc->length8 = (u16)(packetlen_aligned >> 3);
+	desc->transactionid = requestid;
+	desc->reserved = 0;
+	desc->rangecount = 1;
+
+	bufferlist[0].iov_base = desc;
+	bufferlist[0].iov_len = desc_size;
+	bufferlist[1].iov_base = buffer;
+	bufferlist[1].iov_len = bufferlen;
+	bufferlist[2].iov_base = &aligned_data;
+	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
+
+	return hv_ringbuffer_write(channel, bufferlist, 3);
+}
+EXPORT_SYMBOL_GPL(vmbus_sendpacket_mpb_desc);
+
+/**
+ * vmbus_recvpacket() - Retrieve the user packet on the specified channel
+ * @channel: Pointer to vmbus_channel structure.
+ * @buffer: Pointer to the buffer you want to receive the data into.
+ * @bufferlen: Maximum size of what the the buffer will hold
+ * @buffer_actual_len: The actual size of the data after it was received
+ * @requestid: Identifier of the request
+ *
+ * Receives directly from the hyper-v vmbus and puts the data it received
+ * into Buffer. This will receive the data unparsed from hyper-v.
+ *
+ * Mainly used by Hyper-V drivers.
+ */
+static inline int
+__vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
+		   u32 bufferlen, u32 *buffer_actual_len, u64 *requestid,
+		   bool raw)
+{
+	return hv_ringbuffer_read(channel, buffer, bufferlen,
+				  buffer_actual_len, requestid, raw);
+
+}
+
+int vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
+		     u32 bufferlen, u32 *buffer_actual_len,
+		     u64 *requestid)
+{
+	return __vmbus_recvpacket(channel, buffer, bufferlen,
+				  buffer_actual_len, requestid, false);
+}
+EXPORT_SYMBOL(vmbus_recvpacket);
+
+/*
+ * vmbus_recvpacket_raw - Retrieve the raw packet on the specified channel
+ */
+int vmbus_recvpacket_raw(struct vmbus_channel *channel, void *buffer,
+			      u32 bufferlen, u32 *buffer_actual_len,
+			      u64 *requestid)
+{
+	return __vmbus_recvpacket(channel, buffer, bufferlen,
+				  buffer_actual_len, requestid, true);
+}
+EXPORT_SYMBOL_GPL(vmbus_recvpacket_raw);