Adding upstream version 4.19.249.upstream/4.19.249

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

22 files changed, 9041 insertions, 0 deletions

diff --git a/drivers/misc/vmw_vmci/Kconfig b/drivers/misc/vmw_vmci/Kconfig
new file mode 100644
index 000000000..39c2ecadb
--- /dev/null
+++ b/drivers/misc/vmw_vmci/Kconfig
@@ -0,0 +1,16 @@
+#
+# VMware VMCI device
+#
+
+config VMWARE_VMCI
+	tristate "VMware VMCI Driver"
+	depends on X86 && PCI
+	help
+	  This is VMware's Virtual Machine Communication Interface.  It enables
+	  high-speed communication between host and guest in a virtual
+	  environment via the VMCI virtual device.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called vmw_vmci.
diff --git a/drivers/misc/vmw_vmci/Makefile b/drivers/misc/vmw_vmci/Makefile
new file mode 100644
index 000000000..4da9893c3
--- /dev/null
+++ b/drivers/misc/vmw_vmci/Makefile
@@ -0,0 +1,4 @@
+obj-$(CONFIG_VMWARE_VMCI) += vmw_vmci.o
+vmw_vmci-y += vmci_context.o vmci_datagram.o vmci_doorbell.o \
+	vmci_driver.o vmci_event.o vmci_guest.o vmci_handle_array.o \
+	vmci_host.o vmci_queue_pair.o vmci_resource.o vmci_route.o
diff --git a/drivers/misc/vmw_vmci/vmci_context.c b/drivers/misc/vmw_vmci/vmci_context.c
new file mode 100644
index 000000000..26e20b091
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_context.c
@@ -0,0 +1,1225 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+#include <linux/highmem.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/slab.h>
+
+#include "vmci_queue_pair.h"
+#include "vmci_datagram.h"
+#include "vmci_doorbell.h"
+#include "vmci_context.h"
+#include "vmci_driver.h"
+#include "vmci_event.h"
+
+/* Use a wide upper bound for the maximum contexts. */
+#define VMCI_MAX_CONTEXTS 2000
+
+/*
+ * List of current VMCI contexts.  Contexts can be added by
+ * vmci_ctx_create() and removed via vmci_ctx_destroy().
+ * These, along with context lookup, are protected by the
+ * list structure's lock.
+ */
+static struct {
+	struct list_head head;
+	spinlock_t lock; /* Spinlock for context list operations */
+} ctx_list = {
+	.head = LIST_HEAD_INIT(ctx_list.head),
+	.lock = __SPIN_LOCK_UNLOCKED(ctx_list.lock),
+};
+
+/* Used by contexts that did not set up notify flag pointers */
+static bool ctx_dummy_notify;
+
+static void ctx_signal_notify(struct vmci_ctx *context)
+{
+	*context->notify = true;
+}
+
+static void ctx_clear_notify(struct vmci_ctx *context)
+{
+	*context->notify = false;
+}
+
+/*
+ * If nothing requires the attention of the guest, clears both
+ * notify flag and call.
+ */
+static void ctx_clear_notify_call(struct vmci_ctx *context)
+{
+	if (context->pending_datagrams == 0 &&
+	    vmci_handle_arr_get_size(context->pending_doorbell_array) == 0)
+		ctx_clear_notify(context);
+}
+
+/*
+ * Sets the context's notify flag iff datagrams are pending for this
+ * context.  Called from vmci_setup_notify().
+ */
+void vmci_ctx_check_signal_notify(struct vmci_ctx *context)
+{
+	spin_lock(&context->lock);
+	if (context->pending_datagrams)
+		ctx_signal_notify(context);
+	spin_unlock(&context->lock);
+}
+
+/*
+ * Allocates and initializes a VMCI context.
+ */
+struct vmci_ctx *vmci_ctx_create(u32 cid, u32 priv_flags,
+				 uintptr_t event_hnd,
+				 int user_version,
+				 const struct cred *cred)
+{
+	struct vmci_ctx *context;
+	int error;
+
+	if (cid == VMCI_INVALID_ID) {
+		pr_devel("Invalid context ID for VMCI context\n");
+		error = -EINVAL;
+		goto err_out;
+	}
+
+	if (priv_flags & ~VMCI_PRIVILEGE_ALL_FLAGS) {
+		pr_devel("Invalid flag (flags=0x%x) for VMCI context\n",
+			 priv_flags);
+		error = -EINVAL;
+		goto err_out;
+	}
+
+	if (user_version == 0) {
+		pr_devel("Invalid suer_version %d\n", user_version);
+		error = -EINVAL;
+		goto err_out;
+	}
+
+	context = kzalloc(sizeof(*context), GFP_KERNEL);
+	if (!context) {
+		pr_warn("Failed to allocate memory for VMCI context\n");
+		error = -EINVAL;
+		goto err_out;
+	}
+
+	kref_init(&context->kref);
+	spin_lock_init(&context->lock);
+	INIT_LIST_HEAD(&context->list_item);
+	INIT_LIST_HEAD(&context->datagram_queue);
+	INIT_LIST_HEAD(&context->notifier_list);
+
+	/* Initialize host-specific VMCI context. */
+	init_waitqueue_head(&context->host_context.wait_queue);
+
+	context->queue_pair_array =
+		vmci_handle_arr_create(0, VMCI_MAX_GUEST_QP_COUNT);
+	if (!context->queue_pair_array) {
+		error = -ENOMEM;
+		goto err_free_ctx;
+	}
+
+	context->doorbell_array =
+		vmci_handle_arr_create(0, VMCI_MAX_GUEST_DOORBELL_COUNT);
+	if (!context->doorbell_array) {
+		error = -ENOMEM;
+		goto err_free_qp_array;
+	}
+
+	context->pending_doorbell_array =
+		vmci_handle_arr_create(0, VMCI_MAX_GUEST_DOORBELL_COUNT);
+	if (!context->pending_doorbell_array) {
+		error = -ENOMEM;
+		goto err_free_db_array;
+	}
+
+	context->user_version = user_version;
+
+	context->priv_flags = priv_flags;
+
+	if (cred)
+		context->cred = get_cred(cred);
+
+	context->notify = &ctx_dummy_notify;
+	context->notify_page = NULL;
+
+	/*
+	 * If we collide with an existing context we generate a new
+	 * and use it instead. The VMX will determine if regeneration
+	 * is okay. Since there isn't 4B - 16 VMs running on a given
+	 * host, the below loop will terminate.
+	 */
+	spin_lock(&ctx_list.lock);
+
+	while (vmci_ctx_exists(cid)) {
+		/* We reserve the lowest 16 ids for fixed contexts. */
+		cid = max(cid, VMCI_RESERVED_CID_LIMIT - 1) + 1;
+		if (cid == VMCI_INVALID_ID)
+			cid = VMCI_RESERVED_CID_LIMIT;
+	}
+	context->cid = cid;
+
+	list_add_tail_rcu(&context->list_item, &ctx_list.head);
+	spin_unlock(&ctx_list.lock);
+
+	return context;
+
+ err_free_db_array:
+	vmci_handle_arr_destroy(context->doorbell_array);
+ err_free_qp_array:
+	vmci_handle_arr_destroy(context->queue_pair_array);
+ err_free_ctx:
+	kfree(context);
+ err_out:
+	return ERR_PTR(error);
+}
+
+/*
+ * Destroy VMCI context.
+ */
+void vmci_ctx_destroy(struct vmci_ctx *context)
+{
+	spin_lock(&ctx_list.lock);
+	list_del_rcu(&context->list_item);
+	spin_unlock(&ctx_list.lock);
+	synchronize_rcu();
+
+	vmci_ctx_put(context);
+}
+
+/*
+ * Fire notification for all contexts interested in given cid.
+ */
+static int ctx_fire_notification(u32 context_id, u32 priv_flags)
+{
+	u32 i, array_size;
+	struct vmci_ctx *sub_ctx;
+	struct vmci_handle_arr *subscriber_array;
+	struct vmci_handle context_handle =
+		vmci_make_handle(context_id, VMCI_EVENT_HANDLER);
+
+	/*
+	 * We create an array to hold the subscribers we find when
+	 * scanning through all contexts.
+	 */
+	subscriber_array = vmci_handle_arr_create(0, VMCI_MAX_CONTEXTS);
+	if (subscriber_array == NULL)
+		return VMCI_ERROR_NO_MEM;
+
+	/*
+	 * Scan all contexts to find who is interested in being
+	 * notified about given contextID.
+	 */
+	rcu_read_lock();
+	list_for_each_entry_rcu(sub_ctx, &ctx_list.head, list_item) {
+		struct vmci_handle_list *node;
+
+		/*
+		 * We only deliver notifications of the removal of
+		 * contexts, if the two contexts are allowed to
+		 * interact.
+		 */
+		if (vmci_deny_interaction(priv_flags, sub_ctx->priv_flags))
+			continue;
+
+		list_for_each_entry_rcu(node, &sub_ctx->notifier_list, node) {
+			if (!vmci_handle_is_equal(node->handle, context_handle))
+				continue;
+
+			vmci_handle_arr_append_entry(&subscriber_array,
+					vmci_make_handle(sub_ctx->cid,
+							 VMCI_EVENT_HANDLER));
+		}
+	}
+	rcu_read_unlock();
+
+	/* Fire event to all subscribers. */
+	array_size = vmci_handle_arr_get_size(subscriber_array);
+	for (i = 0; i < array_size; i++) {
+		int result;
+		struct vmci_event_ctx ev;
+
+		ev.msg.hdr.dst = vmci_handle_arr_get_entry(subscriber_array, i);
+		ev.msg.hdr.src = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+						  VMCI_CONTEXT_RESOURCE_ID);
+		ev.msg.hdr.payload_size = sizeof(ev) - sizeof(ev.msg.hdr);
+		ev.msg.event_data.event = VMCI_EVENT_CTX_REMOVED;
+		ev.payload.context_id = context_id;
+
+		result = vmci_datagram_dispatch(VMCI_HYPERVISOR_CONTEXT_ID,
+						&ev.msg.hdr, false);
+		if (result < VMCI_SUCCESS) {
+			pr_devel("Failed to enqueue event datagram (type=%d) for context (ID=0x%x)\n",
+				 ev.msg.event_data.event,
+				 ev.msg.hdr.dst.context);
+			/* We continue to enqueue on next subscriber. */
+		}
+	}
+	vmci_handle_arr_destroy(subscriber_array);
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Returns the current number of pending datagrams. The call may
+ * also serve as a synchronization point for the datagram queue,
+ * as no enqueue operations can occur concurrently.
+ */
+int vmci_ctx_pending_datagrams(u32 cid, u32 *pending)
+{
+	struct vmci_ctx *context;
+
+	context = vmci_ctx_get(cid);
+	if (context == NULL)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	spin_lock(&context->lock);
+	if (pending)
+		*pending = context->pending_datagrams;
+	spin_unlock(&context->lock);
+	vmci_ctx_put(context);
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Queues a VMCI datagram for the appropriate target VM context.
+ */
+int vmci_ctx_enqueue_datagram(u32 cid, struct vmci_datagram *dg)
+{
+	struct vmci_datagram_queue_entry *dq_entry;
+	struct vmci_ctx *context;
+	struct vmci_handle dg_src;
+	size_t vmci_dg_size;
+
+	vmci_dg_size = VMCI_DG_SIZE(dg);
+	if (vmci_dg_size > VMCI_MAX_DG_SIZE) {
+		pr_devel("Datagram too large (bytes=%zu)\n", vmci_dg_size);
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	/* Get the target VM's VMCI context. */
+	context = vmci_ctx_get(cid);
+	if (!context) {
+		pr_devel("Invalid context (ID=0x%x)\n", cid);
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	/* Allocate guest call entry and add it to the target VM's queue. */
+	dq_entry = kmalloc(sizeof(*dq_entry), GFP_KERNEL);
+	if (dq_entry == NULL) {
+		pr_warn("Failed to allocate memory for datagram\n");
+		vmci_ctx_put(context);
+		return VMCI_ERROR_NO_MEM;
+	}
+	dq_entry->dg = dg;
+	dq_entry->dg_size = vmci_dg_size;
+	dg_src = dg->src;
+	INIT_LIST_HEAD(&dq_entry->list_item);
+
+	spin_lock(&context->lock);
+
+	/*
+	 * We put a higher limit on datagrams from the hypervisor.  If
+	 * the pending datagram is not from hypervisor, then we check
+	 * if enqueueing it would exceed the
+	 * VMCI_MAX_DATAGRAM_QUEUE_SIZE limit on the destination.  If
+	 * the pending datagram is from hypervisor, we allow it to be
+	 * queued at the destination side provided we don't reach the
+	 * VMCI_MAX_DATAGRAM_AND_EVENT_QUEUE_SIZE limit.
+	 */
+	if (context->datagram_queue_size + vmci_dg_size >=
+	    VMCI_MAX_DATAGRAM_QUEUE_SIZE &&
+	    (!vmci_handle_is_equal(dg_src,
+				vmci_make_handle
+				(VMCI_HYPERVISOR_CONTEXT_ID,
+				 VMCI_CONTEXT_RESOURCE_ID)) ||
+	     context->datagram_queue_size + vmci_dg_size >=
+	     VMCI_MAX_DATAGRAM_AND_EVENT_QUEUE_SIZE)) {
+		spin_unlock(&context->lock);
+		vmci_ctx_put(context);
+		kfree(dq_entry);
+		pr_devel("Context (ID=0x%x) receive queue is full\n", cid);
+		return VMCI_ERROR_NO_RESOURCES;
+	}
+
+	list_add(&dq_entry->list_item, &context->datagram_queue);
+	context->pending_datagrams++;
+	context->datagram_queue_size += vmci_dg_size;
+	ctx_signal_notify(context);
+	wake_up(&context->host_context.wait_queue);
+	spin_unlock(&context->lock);
+	vmci_ctx_put(context);
+
+	return vmci_dg_size;
+}
+
+/*
+ * Verifies whether a context with the specified context ID exists.
+ * FIXME: utility is dubious as no decisions can be reliably made
+ * using this data as context can appear and disappear at any time.
+ */
+bool vmci_ctx_exists(u32 cid)
+{
+	struct vmci_ctx *context;
+	bool exists = false;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(context, &ctx_list.head, list_item) {
+		if (context->cid == cid) {
+			exists = true;
+			break;
+		}
+	}
+
+	rcu_read_unlock();
+	return exists;
+}
+
+/*
+ * Retrieves VMCI context corresponding to the given cid.
+ */
+struct vmci_ctx *vmci_ctx_get(u32 cid)
+{
+	struct vmci_ctx *c, *context = NULL;
+
+	if (cid == VMCI_INVALID_ID)
+		return NULL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(c, &ctx_list.head, list_item) {
+		if (c->cid == cid) {
+			/*
+			 * The context owner drops its own reference to the
+			 * context only after removing it from the list and
+			 * waiting for RCU grace period to expire. This
+			 * means that we are not about to increase the
+			 * reference count of something that is in the
+			 * process of being destroyed.
+			 */
+			context = c;
+			kref_get(&context->kref);
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	return context;
+}
+
+/*
+ * Deallocates all parts of a context data structure. This
+ * function doesn't lock the context, because it assumes that
+ * the caller was holding the last reference to context.
+ */
+static void ctx_free_ctx(struct kref *kref)
+{
+	struct vmci_ctx *context = container_of(kref, struct vmci_ctx, kref);
+	struct vmci_datagram_queue_entry *dq_entry, *dq_entry_tmp;
+	struct vmci_handle temp_handle;
+	struct vmci_handle_list *notifier, *tmp;
+
+	/*
+	 * Fire event to all contexts interested in knowing this
+	 * context is dying.
+	 */
+	ctx_fire_notification(context->cid, context->priv_flags);
+
+	/*
+	 * Cleanup all queue pair resources attached to context.  If
+	 * the VM dies without cleaning up, this code will make sure
+	 * that no resources are leaked.
+	 */
+	temp_handle = vmci_handle_arr_get_entry(context->queue_pair_array, 0);
+	while (!vmci_handle_is_equal(temp_handle, VMCI_INVALID_HANDLE)) {
+		if (vmci_qp_broker_detach(temp_handle,
+					  context) < VMCI_SUCCESS) {
+			/*
+			 * When vmci_qp_broker_detach() succeeds it
+			 * removes the handle from the array.  If
+			 * detach fails, we must remove the handle
+			 * ourselves.
+			 */
+			vmci_handle_arr_remove_entry(context->queue_pair_array,
+						     temp_handle);
+		}
+		temp_handle =
+		    vmci_handle_arr_get_entry(context->queue_pair_array, 0);
+	}
+
+	/*
+	 * It is fine to destroy this without locking the callQueue, as
+	 * this is the only thread having a reference to the context.
+	 */
+	list_for_each_entry_safe(dq_entry, dq_entry_tmp,
+				 &context->datagram_queue, list_item) {
+		WARN_ON(dq_entry->dg_size != VMCI_DG_SIZE(dq_entry->dg));
+		list_del(&dq_entry->list_item);
+		kfree(dq_entry->dg);
+		kfree(dq_entry);
+	}
+
+	list_for_each_entry_safe(notifier, tmp,
+				 &context->notifier_list, node) {
+		list_del(&notifier->node);
+		kfree(notifier);
+	}
+
+	vmci_handle_arr_destroy(context->queue_pair_array);
+	vmci_handle_arr_destroy(context->doorbell_array);
+	vmci_handle_arr_destroy(context->pending_doorbell_array);
+	vmci_ctx_unset_notify(context);
+	if (context->cred)
+		put_cred(context->cred);
+	kfree(context);
+}
+
+/*
+ * Drops reference to VMCI context. If this is the last reference to
+ * the context it will be deallocated. A context is created with
+ * a reference count of one, and on destroy, it is removed from
+ * the context list before its reference count is decremented. Thus,
+ * if we reach zero, we are sure that nobody else are about to increment
+ * it (they need the entry in the context list for that), and so there
+ * is no need for locking.
+ */
+void vmci_ctx_put(struct vmci_ctx *context)
+{
+	kref_put(&context->kref, ctx_free_ctx);
+}
+
+/*
+ * Dequeues the next datagram and returns it to caller.
+ * The caller passes in a pointer to the max size datagram
+ * it can handle and the datagram is only unqueued if the
+ * size is less than max_size. If larger max_size is set to
+ * the size of the datagram to give the caller a chance to
+ * set up a larger buffer for the guestcall.
+ */
+int vmci_ctx_dequeue_datagram(struct vmci_ctx *context,
+			      size_t *max_size,
+			      struct vmci_datagram **dg)
+{
+	struct vmci_datagram_queue_entry *dq_entry;
+	struct list_head *list_item;
+	int rv;
+
+	/* Dequeue the next datagram entry. */
+	spin_lock(&context->lock);
+	if (context->pending_datagrams == 0) {
+		ctx_clear_notify_call(context);
+		spin_unlock(&context->lock);
+		pr_devel("No datagrams pending\n");
+		return VMCI_ERROR_NO_MORE_DATAGRAMS;
+	}
+
+	list_item = context->datagram_queue.next;
+
+	dq_entry =
+	    list_entry(list_item, struct vmci_datagram_queue_entry, list_item);
+
+	/* Check size of caller's buffer. */
+	if (*max_size < dq_entry->dg_size) {
+		*max_size = dq_entry->dg_size;
+		spin_unlock(&context->lock);
+		pr_devel("Caller's buffer should be at least (size=%u bytes)\n",
+			 (u32) *max_size);
+		return VMCI_ERROR_NO_MEM;
+	}
+
+	list_del(list_item);
+	context->pending_datagrams--;
+	context->datagram_queue_size -= dq_entry->dg_size;
+	if (context->pending_datagrams == 0) {
+		ctx_clear_notify_call(context);
+		rv = VMCI_SUCCESS;
+	} else {
+		/*
+		 * Return the size of the next datagram.
+		 */
+		struct vmci_datagram_queue_entry *next_entry;
+
+		list_item = context->datagram_queue.next;
+		next_entry =
+		    list_entry(list_item, struct vmci_datagram_queue_entry,
+			       list_item);
+
+		/*
+		 * The following size_t -> int truncation is fine as
+		 * the maximum size of a (routable) datagram is 68KB.
+		 */
+		rv = (int)next_entry->dg_size;
+	}
+	spin_unlock(&context->lock);
+
+	/* Caller must free datagram. */
+	*dg = dq_entry->dg;
+	dq_entry->dg = NULL;
+	kfree(dq_entry);
+
+	return rv;
+}
+
+/*
+ * Reverts actions set up by vmci_setup_notify().  Unmaps and unlocks the
+ * page mapped/locked by vmci_setup_notify().
+ */
+void vmci_ctx_unset_notify(struct vmci_ctx *context)
+{
+	struct page *notify_page;
+
+	spin_lock(&context->lock);
+
+	notify_page = context->notify_page;
+	context->notify = &ctx_dummy_notify;
+	context->notify_page = NULL;
+
+	spin_unlock(&context->lock);
+
+	if (notify_page) {
+		kunmap(notify_page);
+		put_page(notify_page);
+	}
+}
+
+/*
+ * Add remote_cid to list of contexts current contexts wants
+ * notifications from/about.
+ */
+int vmci_ctx_add_notification(u32 context_id, u32 remote_cid)
+{
+	struct vmci_ctx *context;
+	struct vmci_handle_list *notifier, *n;
+	int result;
+	bool exists = false;
+
+	context = vmci_ctx_get(context_id);
+	if (!context)
+		return VMCI_ERROR_NOT_FOUND;
+
+	if (VMCI_CONTEXT_IS_VM(context_id) && VMCI_CONTEXT_IS_VM(remote_cid)) {
+		pr_devel("Context removed notifications for other VMs not supported (src=0x%x, remote=0x%x)\n",
+			 context_id, remote_cid);
+		result = VMCI_ERROR_DST_UNREACHABLE;
+		goto out;
+	}
+
+	if (context->priv_flags & VMCI_PRIVILEGE_FLAG_RESTRICTED) {
+		result = VMCI_ERROR_NO_ACCESS;
+		goto out;
+	}
+
+	notifier = kmalloc(sizeof(struct vmci_handle_list), GFP_KERNEL);
+	if (!notifier) {
+		result = VMCI_ERROR_NO_MEM;
+		goto out;
+	}
+
+	INIT_LIST_HEAD(&notifier->node);
+	notifier->handle = vmci_make_handle(remote_cid, VMCI_EVENT_HANDLER);
+
+	spin_lock(&context->lock);
+
+	if (context->n_notifiers < VMCI_MAX_CONTEXTS) {
+		list_for_each_entry(n, &context->notifier_list, node) {
+			if (vmci_handle_is_equal(n->handle, notifier->handle)) {
+				exists = true;
+				break;
+			}
+		}
+
+		if (exists) {
+			kfree(notifier);
+			result = VMCI_ERROR_ALREADY_EXISTS;
+		} else {
+			list_add_tail_rcu(&notifier->node,
+					  &context->notifier_list);
+			context->n_notifiers++;
+			result = VMCI_SUCCESS;
+		}
+	} else {
+		kfree(notifier);
+		result = VMCI_ERROR_NO_MEM;
+	}
+
+	spin_unlock(&context->lock);
+
+ out:
+	vmci_ctx_put(context);
+	return result;
+}
+
+/*
+ * Remove remote_cid from current context's list of contexts it is
+ * interested in getting notifications from/about.
+ */
+int vmci_ctx_remove_notification(u32 context_id, u32 remote_cid)
+{
+	struct vmci_ctx *context;
+	struct vmci_handle_list *notifier, *tmp;
+	struct vmci_handle handle;
+	bool found = false;
+
+	context = vmci_ctx_get(context_id);
+	if (!context)
+		return VMCI_ERROR_NOT_FOUND;
+
+	handle = vmci_make_handle(remote_cid, VMCI_EVENT_HANDLER);
+
+	spin_lock(&context->lock);
+	list_for_each_entry_safe(notifier, tmp,
+				 &context->notifier_list, node) {
+		if (vmci_handle_is_equal(notifier->handle, handle)) {
+			list_del_rcu(&notifier->node);
+			context->n_notifiers--;
+			found = true;
+			break;
+		}
+	}
+	spin_unlock(&context->lock);
+
+	if (found) {
+		synchronize_rcu();
+		kfree(notifier);
+	}
+
+	vmci_ctx_put(context);
+
+	return found ? VMCI_SUCCESS : VMCI_ERROR_NOT_FOUND;
+}
+
+static int vmci_ctx_get_chkpt_notifiers(struct vmci_ctx *context,
+					u32 *buf_size, void **pbuf)
+{
+	u32 *notifiers;
+	size_t data_size;
+	struct vmci_handle_list *entry;
+	int i = 0;
+
+	if (context->n_notifiers == 0) {
+		*buf_size = 0;
+		*pbuf = NULL;
+		return VMCI_SUCCESS;
+	}
+
+	data_size = context->n_notifiers * sizeof(*notifiers);
+	if (*buf_size < data_size) {
+		*buf_size = data_size;
+		return VMCI_ERROR_MORE_DATA;
+	}
+
+	notifiers = kmalloc(data_size, GFP_ATOMIC); /* FIXME: want GFP_KERNEL */
+	if (!notifiers)
+		return VMCI_ERROR_NO_MEM;
+
+	list_for_each_entry(entry, &context->notifier_list, node)
+		notifiers[i++] = entry->handle.context;
+
+	*buf_size = data_size;
+	*pbuf = notifiers;
+	return VMCI_SUCCESS;
+}
+
+static int vmci_ctx_get_chkpt_doorbells(struct vmci_ctx *context,
+					u32 *buf_size, void **pbuf)
+{
+	struct dbell_cpt_state *dbells;
+	u32 i, n_doorbells;
+
+	n_doorbells = vmci_handle_arr_get_size(context->doorbell_array);
+	if (n_doorbells > 0) {
+		size_t data_size = n_doorbells * sizeof(*dbells);
+		if (*buf_size < data_size) {
+			*buf_size = data_size;
+			return VMCI_ERROR_MORE_DATA;
+		}
+
+		dbells = kzalloc(data_size, GFP_ATOMIC);
+		if (!dbells)
+			return VMCI_ERROR_NO_MEM;
+
+		for (i = 0; i < n_doorbells; i++)
+			dbells[i].handle = vmci_handle_arr_get_entry(
+						context->doorbell_array, i);
+
+		*buf_size = data_size;
+		*pbuf = dbells;
+	} else {
+		*buf_size = 0;
+		*pbuf = NULL;
+	}
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Get current context's checkpoint state of given type.
+ */
+int vmci_ctx_get_chkpt_state(u32 context_id,
+			     u32 cpt_type,
+			     u32 *buf_size,
+			     void **pbuf)
+{
+	struct vmci_ctx *context;
+	int result;
+
+	context = vmci_ctx_get(context_id);
+	if (!context)
+		return VMCI_ERROR_NOT_FOUND;
+
+	spin_lock(&context->lock);
+
+	switch (cpt_type) {
+	case VMCI_NOTIFICATION_CPT_STATE:
+		result = vmci_ctx_get_chkpt_notifiers(context, buf_size, pbuf);
+		break;
+
+	case VMCI_WELLKNOWN_CPT_STATE:
+		/*
+		 * For compatibility with VMX'en with VM to VM communication, we
+		 * always return zero wellknown handles.
+		 */
+
+		*buf_size = 0;
+		*pbuf = NULL;
+		result = VMCI_SUCCESS;
+		break;
+
+	case VMCI_DOORBELL_CPT_STATE:
+		result = vmci_ctx_get_chkpt_doorbells(context, buf_size, pbuf);
+		break;
+
+	default:
+		pr_devel("Invalid cpt state (type=%d)\n", cpt_type);
+		result = VMCI_ERROR_INVALID_ARGS;
+		break;
+	}
+
+	spin_unlock(&context->lock);
+	vmci_ctx_put(context);
+
+	return result;
+}
+
+/*
+ * Set current context's checkpoint state of given type.
+ */
+int vmci_ctx_set_chkpt_state(u32 context_id,
+			     u32 cpt_type,
+			     u32 buf_size,
+			     void *cpt_buf)
+{
+	u32 i;
+	u32 current_id;
+	int result = VMCI_SUCCESS;
+	u32 num_ids = buf_size / sizeof(u32);
+
+	if (cpt_type == VMCI_WELLKNOWN_CPT_STATE && num_ids > 0) {
+		/*
+		 * We would end up here if VMX with VM to VM communication
+		 * attempts to restore a checkpoint with wellknown handles.
+		 */
+		pr_warn("Attempt to restore checkpoint with obsolete wellknown handles\n");
+		return VMCI_ERROR_OBSOLETE;
+	}
+
+	if (cpt_type != VMCI_NOTIFICATION_CPT_STATE) {
+		pr_devel("Invalid cpt state (type=%d)\n", cpt_type);
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	for (i = 0; i < num_ids && result == VMCI_SUCCESS; i++) {
+		current_id = ((u32 *)cpt_buf)[i];
+		result = vmci_ctx_add_notification(context_id, current_id);
+		if (result != VMCI_SUCCESS)
+			break;
+	}
+	if (result != VMCI_SUCCESS)
+		pr_devel("Failed to set cpt state (type=%d) (error=%d)\n",
+			 cpt_type, result);
+
+	return result;
+}
+
+/*
+ * Retrieves the specified context's pending notifications in the
+ * form of a handle array. The handle arrays returned are the
+ * actual data - not a copy and should not be modified by the
+ * caller. They must be released using
+ * vmci_ctx_rcv_notifications_release.
+ */
+int vmci_ctx_rcv_notifications_get(u32 context_id,
+				   struct vmci_handle_arr **db_handle_array,
+				   struct vmci_handle_arr **qp_handle_array)
+{
+	struct vmci_ctx *context;
+	int result = VMCI_SUCCESS;
+
+	context = vmci_ctx_get(context_id);
+	if (context == NULL)
+		return VMCI_ERROR_NOT_FOUND;
+
+	spin_lock(&context->lock);
+
+	*db_handle_array = context->pending_doorbell_array;
+	context->pending_doorbell_array =
+		vmci_handle_arr_create(0, VMCI_MAX_GUEST_DOORBELL_COUNT);
+	if (!context->pending_doorbell_array) {
+		context->pending_doorbell_array = *db_handle_array;
+		*db_handle_array = NULL;
+		result = VMCI_ERROR_NO_MEM;
+	}
+	*qp_handle_array = NULL;
+
+	spin_unlock(&context->lock);
+	vmci_ctx_put(context);
+
+	return result;
+}
+
+/*
+ * Releases handle arrays with pending notifications previously
+ * retrieved using vmci_ctx_rcv_notifications_get. If the
+ * notifications were not successfully handed over to the guest,
+ * success must be false.
+ */
+void vmci_ctx_rcv_notifications_release(u32 context_id,
+					struct vmci_handle_arr *db_handle_array,
+					struct vmci_handle_arr *qp_handle_array,
+					bool success)
+{
+	struct vmci_ctx *context = vmci_ctx_get(context_id);
+
+	spin_lock(&context->lock);
+	if (!success) {
+		struct vmci_handle handle;
+
+		/*
+		 * New notifications may have been added while we were not
+		 * holding the context lock, so we transfer any new pending
+		 * doorbell notifications to the old array, and reinstate the
+		 * old array.
+		 */
+
+		handle = vmci_handle_arr_remove_tail(
+					context->pending_doorbell_array);
+		while (!vmci_handle_is_invalid(handle)) {
+			if (!vmci_handle_arr_has_entry(db_handle_array,
+						       handle)) {
+				vmci_handle_arr_append_entry(
+						&db_handle_array, handle);
+			}
+			handle = vmci_handle_arr_remove_tail(
+					context->pending_doorbell_array);
+		}
+		vmci_handle_arr_destroy(context->pending_doorbell_array);
+		context->pending_doorbell_array = db_handle_array;
+		db_handle_array = NULL;
+	} else {
+		ctx_clear_notify_call(context);
+	}
+	spin_unlock(&context->lock);
+	vmci_ctx_put(context);
+
+	if (db_handle_array)
+		vmci_handle_arr_destroy(db_handle_array);
+
+	if (qp_handle_array)
+		vmci_handle_arr_destroy(qp_handle_array);
+}
+
+/*
+ * Registers that a new doorbell handle has been allocated by the
+ * context. Only doorbell handles registered can be notified.
+ */
+int vmci_ctx_dbell_create(u32 context_id, struct vmci_handle handle)
+{
+	struct vmci_ctx *context;
+	int result;
+
+	if (context_id == VMCI_INVALID_ID || vmci_handle_is_invalid(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	context = vmci_ctx_get(context_id);
+	if (context == NULL)
+		return VMCI_ERROR_NOT_FOUND;
+
+	spin_lock(&context->lock);
+	if (!vmci_handle_arr_has_entry(context->doorbell_array, handle))
+		result = vmci_handle_arr_append_entry(&context->doorbell_array,
+						      handle);
+	else
+		result = VMCI_ERROR_DUPLICATE_ENTRY;
+
+	spin_unlock(&context->lock);
+	vmci_ctx_put(context);
+
+	return result;
+}
+
+/*
+ * Unregisters a doorbell handle that was previously registered
+ * with vmci_ctx_dbell_create.
+ */
+int vmci_ctx_dbell_destroy(u32 context_id, struct vmci_handle handle)
+{
+	struct vmci_ctx *context;
+	struct vmci_handle removed_handle;
+
+	if (context_id == VMCI_INVALID_ID || vmci_handle_is_invalid(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	context = vmci_ctx_get(context_id);
+	if (context == NULL)
+		return VMCI_ERROR_NOT_FOUND;
+
+	spin_lock(&context->lock);
+	removed_handle =
+	    vmci_handle_arr_remove_entry(context->doorbell_array, handle);
+	vmci_handle_arr_remove_entry(context->pending_doorbell_array, handle);
+	spin_unlock(&context->lock);
+
+	vmci_ctx_put(context);
+
+	return vmci_handle_is_invalid(removed_handle) ?
+	    VMCI_ERROR_NOT_FOUND : VMCI_SUCCESS;
+}
+
+/*
+ * Unregisters all doorbell handles that were previously
+ * registered with vmci_ctx_dbell_create.
+ */
+int vmci_ctx_dbell_destroy_all(u32 context_id)
+{
+	struct vmci_ctx *context;
+	struct vmci_handle handle;
+
+	if (context_id == VMCI_INVALID_ID)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	context = vmci_ctx_get(context_id);
+	if (context == NULL)
+		return VMCI_ERROR_NOT_FOUND;
+
+	spin_lock(&context->lock);
+	do {
+		struct vmci_handle_arr *arr = context->doorbell_array;
+		handle = vmci_handle_arr_remove_tail(arr);
+	} while (!vmci_handle_is_invalid(handle));
+	do {
+		struct vmci_handle_arr *arr = context->pending_doorbell_array;
+		handle = vmci_handle_arr_remove_tail(arr);
+	} while (!vmci_handle_is_invalid(handle));
+	spin_unlock(&context->lock);
+
+	vmci_ctx_put(context);
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Registers a notification of a doorbell handle initiated by the
+ * specified source context. The notification of doorbells are
+ * subject to the same isolation rules as datagram delivery. To
+ * allow host side senders of notifications a finer granularity
+ * of sender rights than those assigned to the sending context
+ * itself, the host context is required to specify a different
+ * set of privilege flags that will override the privileges of
+ * the source context.
+ */
+int vmci_ctx_notify_dbell(u32 src_cid,
+			  struct vmci_handle handle,
+			  u32 src_priv_flags)
+{
+	struct vmci_ctx *dst_context;
+	int result;
+
+	if (vmci_handle_is_invalid(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	/* Get the target VM's VMCI context. */
+	dst_context = vmci_ctx_get(handle.context);
+	if (!dst_context) {
+		pr_devel("Invalid context (ID=0x%x)\n", handle.context);
+		return VMCI_ERROR_NOT_FOUND;
+	}
+
+	if (src_cid != handle.context) {
+		u32 dst_priv_flags;
+
+		if (VMCI_CONTEXT_IS_VM(src_cid) &&
+		    VMCI_CONTEXT_IS_VM(handle.context)) {
+			pr_devel("Doorbell notification from VM to VM not supported (src=0x%x, dst=0x%x)\n",
+				 src_cid, handle.context);
+			result = VMCI_ERROR_DST_UNREACHABLE;
+			goto out;
+		}
+
+		result = vmci_dbell_get_priv_flags(handle, &dst_priv_flags);
+		if (result < VMCI_SUCCESS) {
+			pr_warn("Failed to get privilege flags for destination (handle=0x%x:0x%x)\n",
+				handle.context, handle.resource);
+			goto out;
+		}
+
+		if (src_cid != VMCI_HOST_CONTEXT_ID ||
+		    src_priv_flags == VMCI_NO_PRIVILEGE_FLAGS) {
+			src_priv_flags = vmci_context_get_priv_flags(src_cid);
+		}
+
+		if (vmci_deny_interaction(src_priv_flags, dst_priv_flags)) {
+			result = VMCI_ERROR_NO_ACCESS;
+			goto out;
+		}
+	}
+
+	if (handle.context == VMCI_HOST_CONTEXT_ID) {
+		result = vmci_dbell_host_context_notify(src_cid, handle);
+	} else {
+		spin_lock(&dst_context->lock);
+
+		if (!vmci_handle_arr_has_entry(dst_context->doorbell_array,
+					       handle)) {
+			result = VMCI_ERROR_NOT_FOUND;
+		} else {
+			if (!vmci_handle_arr_has_entry(
+					dst_context->pending_doorbell_array,
+					handle)) {
+				result = vmci_handle_arr_append_entry(
+					&dst_context->pending_doorbell_array,
+					handle);
+				if (result == VMCI_SUCCESS) {
+					ctx_signal_notify(dst_context);
+					wake_up(&dst_context->host_context.wait_queue);
+				}
+			} else {
+				result = VMCI_SUCCESS;
+			}
+		}
+		spin_unlock(&dst_context->lock);
+	}
+
+ out:
+	vmci_ctx_put(dst_context);
+
+	return result;
+}
+
+bool vmci_ctx_supports_host_qp(struct vmci_ctx *context)
+{
+	return context && context->user_version >= VMCI_VERSION_HOSTQP;
+}
+
+/*
+ * Registers that a new queue pair handle has been allocated by
+ * the context.
+ */
+int vmci_ctx_qp_create(struct vmci_ctx *context, struct vmci_handle handle)
+{
+	int result;
+
+	if (context == NULL || vmci_handle_is_invalid(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	if (!vmci_handle_arr_has_entry(context->queue_pair_array, handle))
+		result = vmci_handle_arr_append_entry(
+			&context->queue_pair_array, handle);
+	else
+		result = VMCI_ERROR_DUPLICATE_ENTRY;
+
+	return result;
+}
+
+/*
+ * Unregisters a queue pair handle that was previously registered
+ * with vmci_ctx_qp_create.
+ */
+int vmci_ctx_qp_destroy(struct vmci_ctx *context, struct vmci_handle handle)
+{
+	struct vmci_handle hndl;
+
+	if (context == NULL || vmci_handle_is_invalid(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	hndl = vmci_handle_arr_remove_entry(context->queue_pair_array, handle);
+
+	return vmci_handle_is_invalid(hndl) ?
+		VMCI_ERROR_NOT_FOUND : VMCI_SUCCESS;
+}
+
+/*
+ * Determines whether a given queue pair handle is registered
+ * with the given context.
+ */
+bool vmci_ctx_qp_exists(struct vmci_ctx *context, struct vmci_handle handle)
+{
+	if (context == NULL || vmci_handle_is_invalid(handle))
+		return false;
+
+	return vmci_handle_arr_has_entry(context->queue_pair_array, handle);
+}
+
+/*
+ * vmci_context_get_priv_flags() - Retrieve privilege flags.
+ * @context_id: The context ID of the VMCI context.
+ *
+ * Retrieves privilege flags of the given VMCI context ID.
+ */
+u32 vmci_context_get_priv_flags(u32 context_id)
+{
+	if (vmci_host_code_active()) {
+		u32 flags;
+		struct vmci_ctx *context;
+
+		context = vmci_ctx_get(context_id);
+		if (!context)
+			return VMCI_LEAST_PRIVILEGE_FLAGS;
+
+		flags = context->priv_flags;
+		vmci_ctx_put(context);
+		return flags;
+	}
+	return VMCI_NO_PRIVILEGE_FLAGS;
+}
+EXPORT_SYMBOL_GPL(vmci_context_get_priv_flags);
+
+/*
+ * vmci_is_context_owner() - Determimnes if user is the context owner
+ * @context_id: The context ID of the VMCI context.
+ * @uid:        The host user id (real kernel value).
+ *
+ * Determines whether a given UID is the owner of given VMCI context.
+ */
+bool vmci_is_context_owner(u32 context_id, kuid_t uid)
+{
+	bool is_owner = false;
+
+	if (vmci_host_code_active()) {
+		struct vmci_ctx *context = vmci_ctx_get(context_id);
+		if (context) {
+			if (context->cred)
+				is_owner = uid_eq(context->cred->uid, uid);
+			vmci_ctx_put(context);
+		}
+	}
+
+	return is_owner;
+}
+EXPORT_SYMBOL_GPL(vmci_is_context_owner);
diff --git a/drivers/misc/vmw_vmci/vmci_context.h b/drivers/misc/vmw_vmci/vmci_context.h
new file mode 100644
index 000000000..24a88e68a
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_context.h
@@ -0,0 +1,182 @@
+/*
+ * VMware VMCI driver (vmciContext.h)
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#ifndef _VMCI_CONTEXT_H_
+#define _VMCI_CONTEXT_H_
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/atomic.h>
+#include <linux/kref.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+#include "vmci_handle_array.h"
+#include "vmci_datagram.h"
+
+/* Used to determine what checkpoint state to get and set. */
+enum {
+	VMCI_NOTIFICATION_CPT_STATE = 1,
+	VMCI_WELLKNOWN_CPT_STATE    = 2,
+	VMCI_DG_OUT_STATE           = 3,
+	VMCI_DG_IN_STATE            = 4,
+	VMCI_DG_IN_SIZE_STATE       = 5,
+	VMCI_DOORBELL_CPT_STATE     = 6,
+};
+
+/* Host specific struct used for signalling */
+struct vmci_host {
+	wait_queue_head_t wait_queue;
+};
+
+struct vmci_handle_list {
+	struct list_head node;
+	struct vmci_handle handle;
+};
+
+struct vmci_ctx {
+	struct list_head list_item;       /* For global VMCI list. */
+	u32 cid;
+	struct kref kref;
+	struct list_head datagram_queue;  /* Head of per VM queue. */
+	u32 pending_datagrams;
+	size_t datagram_queue_size;	  /* Size of datagram queue in bytes. */
+
+	/*
+	 * Version of the code that created
+	 * this context; e.g., VMX.
+	 */
+	int user_version;
+	spinlock_t lock;  /* Locks callQueue and handle_arrays. */
+
+	/*
+	 * queue_pairs attached to.  The array of
+	 * handles for queue pairs is accessed
+	 * from the code for QP API, and there
+	 * it is protected by the QP lock.  It
+	 * is also accessed from the context
+	 * clean up path, which does not
+	 * require a lock.  VMCILock is not
+	 * used to protect the QP array field.
+	 */
+	struct vmci_handle_arr *queue_pair_array;
+
+	/* Doorbells created by context. */
+	struct vmci_handle_arr *doorbell_array;
+
+	/* Doorbells pending for context. */
+	struct vmci_handle_arr *pending_doorbell_array;
+
+	/* Contexts current context is subscribing to. */
+	struct list_head notifier_list;
+	unsigned int n_notifiers;
+
+	struct vmci_host host_context;
+	u32 priv_flags;
+
+	const struct cred *cred;
+	bool *notify;		/* Notify flag pointer - hosted only. */
+	struct page *notify_page;	/* Page backing the notify UVA. */
+};
+
+/* VMCINotifyAddRemoveInfo: Used to add/remove remote context notifications. */
+struct vmci_ctx_info {
+	u32 remote_cid;
+	int result;
+};
+
+/* VMCICptBufInfo: Used to set/get current context's checkpoint state. */
+struct vmci_ctx_chkpt_buf_info {
+	u64 cpt_buf;
+	u32 cpt_type;
+	u32 buf_size;
+	s32 result;
+	u32 _pad;
+};
+
+/*
+ * VMCINotificationReceiveInfo: Used to recieve pending notifications
+ * for doorbells and queue pairs.
+ */
+struct vmci_ctx_notify_recv_info {
+	u64 db_handle_buf_uva;
+	u64 db_handle_buf_size;
+	u64 qp_handle_buf_uva;
+	u64 qp_handle_buf_size;
+	s32 result;
+	u32 _pad;
+};
+
+/*
+ * Utilility function that checks whether two entities are allowed
+ * to interact. If one of them is restricted, the other one must
+ * be trusted.
+ */
+static inline bool vmci_deny_interaction(u32 part_one, u32 part_two)
+{
+	return ((part_one & VMCI_PRIVILEGE_FLAG_RESTRICTED) &&
+		!(part_two & VMCI_PRIVILEGE_FLAG_TRUSTED)) ||
+	       ((part_two & VMCI_PRIVILEGE_FLAG_RESTRICTED) &&
+		!(part_one & VMCI_PRIVILEGE_FLAG_TRUSTED));
+}
+
+struct vmci_ctx *vmci_ctx_create(u32 cid, u32 flags,
+				 uintptr_t event_hnd, int version,
+				 const struct cred *cred);
+void vmci_ctx_destroy(struct vmci_ctx *context);
+
+bool vmci_ctx_supports_host_qp(struct vmci_ctx *context);
+int vmci_ctx_enqueue_datagram(u32 cid, struct vmci_datagram *dg);
+int vmci_ctx_dequeue_datagram(struct vmci_ctx *context,
+			      size_t *max_size, struct vmci_datagram **dg);
+int vmci_ctx_pending_datagrams(u32 cid, u32 *pending);
+struct vmci_ctx *vmci_ctx_get(u32 cid);
+void vmci_ctx_put(struct vmci_ctx *context);
+bool vmci_ctx_exists(u32 cid);
+
+int vmci_ctx_add_notification(u32 context_id, u32 remote_cid);
+int vmci_ctx_remove_notification(u32 context_id, u32 remote_cid);
+int vmci_ctx_get_chkpt_state(u32 context_id, u32 cpt_type,
+			     u32 *num_cids, void **cpt_buf_ptr);
+int vmci_ctx_set_chkpt_state(u32 context_id, u32 cpt_type,
+			     u32 num_cids, void *cpt_buf);
+
+int vmci_ctx_qp_create(struct vmci_ctx *context, struct vmci_handle handle);
+int vmci_ctx_qp_destroy(struct vmci_ctx *context, struct vmci_handle handle);
+bool vmci_ctx_qp_exists(struct vmci_ctx *context, struct vmci_handle handle);
+
+void vmci_ctx_check_signal_notify(struct vmci_ctx *context);
+void vmci_ctx_unset_notify(struct vmci_ctx *context);
+
+int vmci_ctx_dbell_create(u32 context_id, struct vmci_handle handle);
+int vmci_ctx_dbell_destroy(u32 context_id, struct vmci_handle handle);
+int vmci_ctx_dbell_destroy_all(u32 context_id);
+int vmci_ctx_notify_dbell(u32 cid, struct vmci_handle handle,
+			  u32 src_priv_flags);
+
+int vmci_ctx_rcv_notifications_get(u32 context_id, struct vmci_handle_arr
+				   **db_handle_array, struct vmci_handle_arr
+				   **qp_handle_array);
+void vmci_ctx_rcv_notifications_release(u32 context_id, struct vmci_handle_arr
+					*db_handle_array, struct vmci_handle_arr
+					*qp_handle_array, bool success);
+
+static inline u32 vmci_ctx_get_id(struct vmci_ctx *context)
+{
+	if (!context)
+		return VMCI_INVALID_ID;
+	return context->cid;
+}
+
+#endif /* _VMCI_CONTEXT_H_ */
diff --git a/drivers/misc/vmw_vmci/vmci_datagram.c b/drivers/misc/vmw_vmci/vmci_datagram.c
new file mode 100644
index 000000000..8a4b6bbe1
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_datagram.c
@@ -0,0 +1,502 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/bug.h>
+
+#include "vmci_datagram.h"
+#include "vmci_resource.h"
+#include "vmci_context.h"
+#include "vmci_driver.h"
+#include "vmci_event.h"
+#include "vmci_route.h"
+
+/*
+ * struct datagram_entry describes the datagram entity. It is used for datagram
+ * entities created only on the host.
+ */
+struct datagram_entry {
+	struct vmci_resource resource;
+	u32 flags;
+	bool run_delayed;
+	vmci_datagram_recv_cb recv_cb;
+	void *client_data;
+	u32 priv_flags;
+};
+
+struct delayed_datagram_info {
+	struct datagram_entry *entry;
+	struct work_struct work;
+	bool in_dg_host_queue;
+	/* msg and msg_payload must be together. */
+	struct vmci_datagram msg;
+	u8 msg_payload[];
+};
+
+/* Number of in-flight host->host datagrams */
+static atomic_t delayed_dg_host_queue_size = ATOMIC_INIT(0);
+
+/*
+ * Create a datagram entry given a handle pointer.
+ */
+static int dg_create_handle(u32 resource_id,
+			    u32 flags,
+			    u32 priv_flags,
+			    vmci_datagram_recv_cb recv_cb,
+			    void *client_data, struct vmci_handle *out_handle)
+{
+	int result;
+	u32 context_id;
+	struct vmci_handle handle;
+	struct datagram_entry *entry;
+
+	if ((flags & VMCI_FLAG_WELLKNOWN_DG_HND) != 0)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	if ((flags & VMCI_FLAG_ANYCID_DG_HND) != 0) {
+		context_id = VMCI_INVALID_ID;
+	} else {
+		context_id = vmci_get_context_id();
+		if (context_id == VMCI_INVALID_ID)
+			return VMCI_ERROR_NO_RESOURCES;
+	}
+
+	handle = vmci_make_handle(context_id, resource_id);
+
+	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry) {
+		pr_warn("Failed allocating memory for datagram entry\n");
+		return VMCI_ERROR_NO_MEM;
+	}
+
+	entry->run_delayed = (flags & VMCI_FLAG_DG_DELAYED_CB) ? true : false;
+	entry->flags = flags;
+	entry->recv_cb = recv_cb;
+	entry->client_data = client_data;
+	entry->priv_flags = priv_flags;
+
+	/* Make datagram resource live. */
+	result = vmci_resource_add(&entry->resource,
+				   VMCI_RESOURCE_TYPE_DATAGRAM,
+				   handle);
+	if (result != VMCI_SUCCESS) {
+		pr_warn("Failed to add new resource (handle=0x%x:0x%x), error: %d\n",
+			handle.context, handle.resource, result);
+		kfree(entry);
+		return result;
+	}
+
+	*out_handle = vmci_resource_handle(&entry->resource);
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Internal utility function with the same purpose as
+ * vmci_datagram_get_priv_flags that also takes a context_id.
+ */
+static int vmci_datagram_get_priv_flags(u32 context_id,
+					struct vmci_handle handle,
+					u32 *priv_flags)
+{
+	if (context_id == VMCI_INVALID_ID)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	if (context_id == VMCI_HOST_CONTEXT_ID) {
+		struct datagram_entry *src_entry;
+		struct vmci_resource *resource;
+
+		resource = vmci_resource_by_handle(handle,
+						   VMCI_RESOURCE_TYPE_DATAGRAM);
+		if (!resource)
+			return VMCI_ERROR_INVALID_ARGS;
+
+		src_entry = container_of(resource, struct datagram_entry,
+					 resource);
+		*priv_flags = src_entry->priv_flags;
+		vmci_resource_put(resource);
+	} else if (context_id == VMCI_HYPERVISOR_CONTEXT_ID)
+		*priv_flags = VMCI_MAX_PRIVILEGE_FLAGS;
+	else
+		*priv_flags = vmci_context_get_priv_flags(context_id);
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Calls the specified callback in a delayed context.
+ */
+static void dg_delayed_dispatch(struct work_struct *work)
+{
+	struct delayed_datagram_info *dg_info =
+			container_of(work, struct delayed_datagram_info, work);
+
+	dg_info->entry->recv_cb(dg_info->entry->client_data, &dg_info->msg);
+
+	vmci_resource_put(&dg_info->entry->resource);
+
+	if (dg_info->in_dg_host_queue)
+		atomic_dec(&delayed_dg_host_queue_size);
+
+	kfree(dg_info);
+}
+
+/*
+ * Dispatch datagram as a host, to the host, or other vm context. This
+ * function cannot dispatch to hypervisor context handlers. This should
+ * have been handled before we get here by vmci_datagram_dispatch.
+ * Returns number of bytes sent on success, error code otherwise.
+ */
+static int dg_dispatch_as_host(u32 context_id, struct vmci_datagram *dg)
+{
+	int retval;
+	size_t dg_size;
+	u32 src_priv_flags;
+
+	dg_size = VMCI_DG_SIZE(dg);
+
+	/* Host cannot send to the hypervisor. */
+	if (dg->dst.context == VMCI_HYPERVISOR_CONTEXT_ID)
+		return VMCI_ERROR_DST_UNREACHABLE;
+
+	/* Check that source handle matches sending context. */
+	if (dg->src.context != context_id) {
+		pr_devel("Sender context (ID=0x%x) is not owner of src datagram entry (handle=0x%x:0x%x)\n",
+			 context_id, dg->src.context, dg->src.resource);
+		return VMCI_ERROR_NO_ACCESS;
+	}
+
+	/* Get hold of privileges of sending endpoint. */
+	retval = vmci_datagram_get_priv_flags(context_id, dg->src,
+					      &src_priv_flags);
+	if (retval != VMCI_SUCCESS) {
+		pr_warn("Couldn't get privileges (handle=0x%x:0x%x)\n",
+			dg->src.context, dg->src.resource);
+		return retval;
+	}
+
+	/* Determine if we should route to host or guest destination. */
+	if (dg->dst.context == VMCI_HOST_CONTEXT_ID) {
+		/* Route to host datagram entry. */
+		struct datagram_entry *dst_entry;
+		struct vmci_resource *resource;
+
+		if (dg->src.context == VMCI_HYPERVISOR_CONTEXT_ID &&
+		    dg->dst.resource == VMCI_EVENT_HANDLER) {
+			return vmci_event_dispatch(dg);
+		}
+
+		resource = vmci_resource_by_handle(dg->dst,
+						   VMCI_RESOURCE_TYPE_DATAGRAM);
+		if (!resource) {
+			pr_devel("Sending to invalid destination (handle=0x%x:0x%x)\n",
+				 dg->dst.context, dg->dst.resource);
+			return VMCI_ERROR_INVALID_RESOURCE;
+		}
+		dst_entry = container_of(resource, struct datagram_entry,
+					 resource);
+		if (vmci_deny_interaction(src_priv_flags,
+					  dst_entry->priv_flags)) {
+			vmci_resource_put(resource);
+			return VMCI_ERROR_NO_ACCESS;
+		}
+
+		/*
+		 * If a VMCI datagram destined for the host is also sent by the
+		 * host, we always run it delayed. This ensures that no locks
+		 * are held when the datagram callback runs.
+		 */
+		if (dst_entry->run_delayed ||
+		    dg->src.context == VMCI_HOST_CONTEXT_ID) {
+			struct delayed_datagram_info *dg_info;
+
+			if (atomic_add_return(1, &delayed_dg_host_queue_size)
+			    == VMCI_MAX_DELAYED_DG_HOST_QUEUE_SIZE) {
+				atomic_dec(&delayed_dg_host_queue_size);
+				vmci_resource_put(resource);
+				return VMCI_ERROR_NO_MEM;
+			}
+
+			dg_info = kmalloc(sizeof(*dg_info) +
+				    (size_t) dg->payload_size, GFP_ATOMIC);
+			if (!dg_info) {
+				atomic_dec(&delayed_dg_host_queue_size);
+				vmci_resource_put(resource);
+				return VMCI_ERROR_NO_MEM;
+			}
+
+			dg_info->in_dg_host_queue = true;
+			dg_info->entry = dst_entry;
+			memcpy(&dg_info->msg, dg, dg_size);
+
+			INIT_WORK(&dg_info->work, dg_delayed_dispatch);
+			schedule_work(&dg_info->work);
+			retval = VMCI_SUCCESS;
+
+		} else {
+			retval = dst_entry->recv_cb(dst_entry->client_data, dg);
+			vmci_resource_put(resource);
+			if (retval < VMCI_SUCCESS)
+				return retval;
+		}
+	} else {
+		/* Route to destination VM context. */
+		struct vmci_datagram *new_dg;
+
+		if (context_id != dg->dst.context) {
+			if (vmci_deny_interaction(src_priv_flags,
+						  vmci_context_get_priv_flags
+						  (dg->dst.context))) {
+				return VMCI_ERROR_NO_ACCESS;
+			} else if (VMCI_CONTEXT_IS_VM(context_id)) {
+				/*
+				 * If the sending context is a VM, it
+				 * cannot reach another VM.
+				 */
+
+				pr_devel("Datagram communication between VMs not supported (src=0x%x, dst=0x%x)\n",
+					 context_id, dg->dst.context);
+				return VMCI_ERROR_DST_UNREACHABLE;
+			}
+		}
+
+		/* We make a copy to enqueue. */
+		new_dg = kmemdup(dg, dg_size, GFP_KERNEL);
+		if (new_dg == NULL)
+			return VMCI_ERROR_NO_MEM;
+
+		retval = vmci_ctx_enqueue_datagram(dg->dst.context, new_dg);
+		if (retval < VMCI_SUCCESS) {
+			kfree(new_dg);
+			return retval;
+		}
+	}
+
+	/*
+	 * We currently truncate the size to signed 32 bits. This doesn't
+	 * matter for this handler as it only support 4Kb messages.
+	 */
+	return (int)dg_size;
+}
+
+/*
+ * Dispatch datagram as a guest, down through the VMX and potentially to
+ * the host.
+ * Returns number of bytes sent on success, error code otherwise.
+ */
+static int dg_dispatch_as_guest(struct vmci_datagram *dg)
+{
+	int retval;
+	struct vmci_resource *resource;
+
+	resource = vmci_resource_by_handle(dg->src,
+					   VMCI_RESOURCE_TYPE_DATAGRAM);
+	if (!resource)
+		return VMCI_ERROR_NO_HANDLE;
+
+	retval = vmci_send_datagram(dg);
+	vmci_resource_put(resource);
+	return retval;
+}
+
+/*
+ * Dispatch datagram.  This will determine the routing for the datagram
+ * and dispatch it accordingly.
+ * Returns number of bytes sent on success, error code otherwise.
+ */
+int vmci_datagram_dispatch(u32 context_id,
+			   struct vmci_datagram *dg, bool from_guest)
+{
+	int retval;
+	enum vmci_route route;
+
+	BUILD_BUG_ON(sizeof(struct vmci_datagram) != 24);
+
+	if (dg->payload_size > VMCI_MAX_DG_SIZE ||
+	    VMCI_DG_SIZE(dg) > VMCI_MAX_DG_SIZE) {
+		pr_devel("Payload (size=%llu bytes) too big to send\n",
+			 (unsigned long long)dg->payload_size);
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	retval = vmci_route(&dg->src, &dg->dst, from_guest, &route);
+	if (retval < VMCI_SUCCESS) {
+		pr_devel("Failed to route datagram (src=0x%x, dst=0x%x, err=%d)\n",
+			 dg->src.context, dg->dst.context, retval);
+		return retval;
+	}
+
+	if (VMCI_ROUTE_AS_HOST == route) {
+		if (VMCI_INVALID_ID == context_id)
+			context_id = VMCI_HOST_CONTEXT_ID;
+		return dg_dispatch_as_host(context_id, dg);
+	}
+
+	if (VMCI_ROUTE_AS_GUEST == route)
+		return dg_dispatch_as_guest(dg);
+
+	pr_warn("Unknown route (%d) for datagram\n", route);
+	return VMCI_ERROR_DST_UNREACHABLE;
+}
+
+/*
+ * Invoke the handler for the given datagram.  This is intended to be
+ * called only when acting as a guest and receiving a datagram from the
+ * virtual device.
+ */
+int vmci_datagram_invoke_guest_handler(struct vmci_datagram *dg)
+{
+	struct vmci_resource *resource;
+	struct datagram_entry *dst_entry;
+
+	resource = vmci_resource_by_handle(dg->dst,
+					   VMCI_RESOURCE_TYPE_DATAGRAM);
+	if (!resource) {
+		pr_devel("destination (handle=0x%x:0x%x) doesn't exist\n",
+			 dg->dst.context, dg->dst.resource);
+		return VMCI_ERROR_NO_HANDLE;
+	}
+
+	dst_entry = container_of(resource, struct datagram_entry, resource);
+	if (dst_entry->run_delayed) {
+		struct delayed_datagram_info *dg_info;
+
+		dg_info = kmalloc(sizeof(*dg_info) + (size_t)dg->payload_size,
+				  GFP_ATOMIC);
+		if (!dg_info) {
+			vmci_resource_put(resource);
+			return VMCI_ERROR_NO_MEM;
+		}
+
+		dg_info->in_dg_host_queue = false;
+		dg_info->entry = dst_entry;
+		memcpy(&dg_info->msg, dg, VMCI_DG_SIZE(dg));
+
+		INIT_WORK(&dg_info->work, dg_delayed_dispatch);
+		schedule_work(&dg_info->work);
+	} else {
+		dst_entry->recv_cb(dst_entry->client_data, dg);
+		vmci_resource_put(resource);
+	}
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * vmci_datagram_create_handle_priv() - Create host context datagram endpoint
+ * @resource_id:        The resource ID.
+ * @flags:      Datagram Flags.
+ * @priv_flags: Privilege Flags.
+ * @recv_cb:    Callback when receiving datagrams.
+ * @client_data:        Pointer for a datagram_entry struct
+ * @out_handle: vmci_handle that is populated as a result of this function.
+ *
+ * Creates a host context datagram endpoint and returns a handle to it.
+ */
+int vmci_datagram_create_handle_priv(u32 resource_id,
+				     u32 flags,
+				     u32 priv_flags,
+				     vmci_datagram_recv_cb recv_cb,
+				     void *client_data,
+				     struct vmci_handle *out_handle)
+{
+	if (out_handle == NULL)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	if (recv_cb == NULL) {
+		pr_devel("Client callback needed when creating datagram\n");
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	if (priv_flags & ~VMCI_PRIVILEGE_ALL_FLAGS)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	return dg_create_handle(resource_id, flags, priv_flags, recv_cb,
+				client_data, out_handle);
+}
+EXPORT_SYMBOL_GPL(vmci_datagram_create_handle_priv);
+
+/*
+ * vmci_datagram_create_handle() - Create host context datagram endpoint
+ * @resource_id:        Resource ID.
+ * @flags:      Datagram Flags.
+ * @recv_cb:    Callback when receiving datagrams.
+ * @client_ata: Pointer for a datagram_entry struct
+ * @out_handle: vmci_handle that is populated as a result of this function.
+ *
+ * Creates a host context datagram endpoint and returns a handle to
+ * it.  Same as vmci_datagram_create_handle_priv without the priviledge
+ * flags argument.
+ */
+int vmci_datagram_create_handle(u32 resource_id,
+				u32 flags,
+				vmci_datagram_recv_cb recv_cb,
+				void *client_data,
+				struct vmci_handle *out_handle)
+{
+	return vmci_datagram_create_handle_priv(
+		resource_id, flags,
+		VMCI_DEFAULT_PROC_PRIVILEGE_FLAGS,
+		recv_cb, client_data,
+		out_handle);
+}
+EXPORT_SYMBOL_GPL(vmci_datagram_create_handle);
+
+/*
+ * vmci_datagram_destroy_handle() - Destroys datagram handle
+ * @handle:     vmci_handle to be destroyed and reaped.
+ *
+ * Use this function to destroy any datagram handles created by
+ * vmci_datagram_create_handle{,Priv} functions.
+ */
+int vmci_datagram_destroy_handle(struct vmci_handle handle)
+{
+	struct datagram_entry *entry;
+	struct vmci_resource *resource;
+
+	resource = vmci_resource_by_handle(handle, VMCI_RESOURCE_TYPE_DATAGRAM);
+	if (!resource) {
+		pr_devel("Failed to destroy datagram (handle=0x%x:0x%x)\n",
+			 handle.context, handle.resource);
+		return VMCI_ERROR_NOT_FOUND;
+	}
+
+	entry = container_of(resource, struct datagram_entry, resource);
+
+	vmci_resource_put(&entry->resource);
+	vmci_resource_remove(&entry->resource);
+	kfree(entry);
+
+	return VMCI_SUCCESS;
+}
+EXPORT_SYMBOL_GPL(vmci_datagram_destroy_handle);
+
+/*
+ * vmci_datagram_send() - Send a datagram
+ * @msg:        The datagram to send.
+ *
+ * Sends the provided datagram on its merry way.
+ */
+int vmci_datagram_send(struct vmci_datagram *msg)
+{
+	if (msg == NULL)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	return vmci_datagram_dispatch(VMCI_INVALID_ID, msg, false);
+}
+EXPORT_SYMBOL_GPL(vmci_datagram_send);
diff --git a/drivers/misc/vmw_vmci/vmci_datagram.h b/drivers/misc/vmw_vmci/vmci_datagram.h
new file mode 100644
index 000000000..eb4aab7f6
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_datagram.h
@@ -0,0 +1,52 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#ifndef _VMCI_DATAGRAM_H_
+#define _VMCI_DATAGRAM_H_
+
+#include <linux/types.h>
+#include <linux/list.h>
+
+#include "vmci_context.h"
+
+#define VMCI_MAX_DELAYED_DG_HOST_QUEUE_SIZE 256
+
+/*
+ * The struct vmci_datagram_queue_entry is a queue header for the in-kernel VMCI
+ * datagram queues. It is allocated in non-paged memory, as the
+ * content is accessed while holding a spinlock. The pending datagram
+ * itself may be allocated from paged memory. We shadow the size of
+ * the datagram in the non-paged queue entry as this size is used
+ * while holding the same spinlock as above.
+ */
+struct vmci_datagram_queue_entry {
+	struct list_head list_item;	/* For queuing. */
+	size_t dg_size;		/* Size of datagram. */
+	struct vmci_datagram *dg;	/* Pending datagram. */
+};
+
+/* VMCIDatagramSendRecvInfo */
+struct vmci_datagram_snd_rcv_info {
+	u64 addr;
+	u32 len;
+	s32 result;
+};
+
+/* Datagram API for non-public use. */
+int vmci_datagram_dispatch(u32 context_id, struct vmci_datagram *dg,
+			   bool from_guest);
+int vmci_datagram_invoke_guest_handler(struct vmci_datagram *dg);
+
+#endif /* _VMCI_DATAGRAM_H_ */
diff --git a/drivers/misc/vmw_vmci/vmci_doorbell.c b/drivers/misc/vmw_vmci/vmci_doorbell.c
new file mode 100644
index 000000000..458121034
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_doorbell.c
@@ -0,0 +1,609 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+#include <linux/completion.h>
+#include <linux/hash.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include "vmci_datagram.h"
+#include "vmci_doorbell.h"
+#include "vmci_resource.h"
+#include "vmci_driver.h"
+#include "vmci_route.h"
+
+
+#define VMCI_DOORBELL_INDEX_BITS	6
+#define VMCI_DOORBELL_INDEX_TABLE_SIZE	(1 << VMCI_DOORBELL_INDEX_BITS)
+#define VMCI_DOORBELL_HASH(_idx)	hash_32(_idx, VMCI_DOORBELL_INDEX_BITS)
+
+/*
+ * DoorbellEntry describes the a doorbell notification handle allocated by the
+ * host.
+ */
+struct dbell_entry {
+	struct vmci_resource resource;
+	struct hlist_node node;
+	struct work_struct work;
+	vmci_callback notify_cb;
+	void *client_data;
+	u32 idx;
+	u32 priv_flags;
+	bool run_delayed;
+	atomic_t active;	/* Only used by guest personality */
+};
+
+/* The VMCI index table keeps track of currently registered doorbells. */
+struct dbell_index_table {
+	spinlock_t lock;	/* Index table lock */
+	struct hlist_head entries[VMCI_DOORBELL_INDEX_TABLE_SIZE];
+};
+
+static struct dbell_index_table vmci_doorbell_it = {
+	.lock = __SPIN_LOCK_UNLOCKED(vmci_doorbell_it.lock),
+};
+
+/*
+ * The max_notify_idx is one larger than the currently known bitmap index in
+ * use, and is used to determine how much of the bitmap needs to be scanned.
+ */
+static u32 max_notify_idx;
+
+/*
+ * The notify_idx_count is used for determining whether there are free entries
+ * within the bitmap (if notify_idx_count + 1 < max_notify_idx).
+ */
+static u32 notify_idx_count;
+
+/*
+ * The last_notify_idx_reserved is used to track the last index handed out - in
+ * the case where multiple handles share a notification index, we hand out
+ * indexes round robin based on last_notify_idx_reserved.
+ */
+static u32 last_notify_idx_reserved;
+
+/* This is a one entry cache used to by the index allocation. */
+static u32 last_notify_idx_released = PAGE_SIZE;
+
+
+/*
+ * Utility function that retrieves the privilege flags associated
+ * with a given doorbell handle. For guest endpoints, the
+ * privileges are determined by the context ID, but for host
+ * endpoints privileges are associated with the complete
+ * handle. Hypervisor endpoints are not yet supported.
+ */
+int vmci_dbell_get_priv_flags(struct vmci_handle handle, u32 *priv_flags)
+{
+	if (priv_flags == NULL || handle.context == VMCI_INVALID_ID)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	if (handle.context == VMCI_HOST_CONTEXT_ID) {
+		struct dbell_entry *entry;
+		struct vmci_resource *resource;
+
+		resource = vmci_resource_by_handle(handle,
+						   VMCI_RESOURCE_TYPE_DOORBELL);
+		if (!resource)
+			return VMCI_ERROR_NOT_FOUND;
+
+		entry = container_of(resource, struct dbell_entry, resource);
+		*priv_flags = entry->priv_flags;
+		vmci_resource_put(resource);
+	} else if (handle.context == VMCI_HYPERVISOR_CONTEXT_ID) {
+		/*
+		 * Hypervisor endpoints for notifications are not
+		 * supported (yet).
+		 */
+		return VMCI_ERROR_INVALID_ARGS;
+	} else {
+		*priv_flags = vmci_context_get_priv_flags(handle.context);
+	}
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Find doorbell entry by bitmap index.
+ */
+static struct dbell_entry *dbell_index_table_find(u32 idx)
+{
+	u32 bucket = VMCI_DOORBELL_HASH(idx);
+	struct dbell_entry *dbell;
+
+	hlist_for_each_entry(dbell, &vmci_doorbell_it.entries[bucket],
+			     node) {
+		if (idx == dbell->idx)
+			return dbell;
+	}
+
+	return NULL;
+}
+
+/*
+ * Add the given entry to the index table.  This willi take a reference to the
+ * entry's resource so that the entry is not deleted before it is removed from
+ * the * table.
+ */
+static void dbell_index_table_add(struct dbell_entry *entry)
+{
+	u32 bucket;
+	u32 new_notify_idx;
+
+	vmci_resource_get(&entry->resource);
+
+	spin_lock_bh(&vmci_doorbell_it.lock);
+
+	/*
+	 * Below we try to allocate an index in the notification
+	 * bitmap with "not too much" sharing between resources. If we
+	 * use less that the full bitmap, we either add to the end if
+	 * there are no unused flags within the currently used area,
+	 * or we search for unused ones. If we use the full bitmap, we
+	 * allocate the index round robin.
+	 */
+	if (max_notify_idx < PAGE_SIZE || notify_idx_count < PAGE_SIZE) {
+		if (last_notify_idx_released < max_notify_idx &&
+		    !dbell_index_table_find(last_notify_idx_released)) {
+			new_notify_idx = last_notify_idx_released;
+			last_notify_idx_released = PAGE_SIZE;
+		} else {
+			bool reused = false;
+			new_notify_idx = last_notify_idx_reserved;
+			if (notify_idx_count + 1 < max_notify_idx) {
+				do {
+					if (!dbell_index_table_find
+					    (new_notify_idx)) {
+						reused = true;
+						break;
+					}
+					new_notify_idx = (new_notify_idx + 1) %
+					    max_notify_idx;
+				} while (new_notify_idx !=
+					 last_notify_idx_released);
+			}
+			if (!reused) {
+				new_notify_idx = max_notify_idx;
+				max_notify_idx++;
+			}
+		}
+	} else {
+		new_notify_idx = (last_notify_idx_reserved + 1) % PAGE_SIZE;
+	}
+
+	last_notify_idx_reserved = new_notify_idx;
+	notify_idx_count++;
+
+	entry->idx = new_notify_idx;
+	bucket = VMCI_DOORBELL_HASH(entry->idx);
+	hlist_add_head(&entry->node, &vmci_doorbell_it.entries[bucket]);
+
+	spin_unlock_bh(&vmci_doorbell_it.lock);
+}
+
+/*
+ * Remove the given entry from the index table.  This will release() the
+ * entry's resource.
+ */
+static void dbell_index_table_remove(struct dbell_entry *entry)
+{
+	spin_lock_bh(&vmci_doorbell_it.lock);
+
+	hlist_del_init(&entry->node);
+
+	notify_idx_count--;
+	if (entry->idx == max_notify_idx - 1) {
+		/*
+		 * If we delete an entry with the maximum known
+		 * notification index, we take the opportunity to
+		 * prune the current max. As there might be other
+		 * unused indices immediately below, we lower the
+		 * maximum until we hit an index in use.
+		 */
+		while (max_notify_idx > 0 &&
+		       !dbell_index_table_find(max_notify_idx - 1))
+			max_notify_idx--;
+	}
+
+	last_notify_idx_released = entry->idx;
+
+	spin_unlock_bh(&vmci_doorbell_it.lock);
+
+	vmci_resource_put(&entry->resource);
+}
+
+/*
+ * Creates a link between the given doorbell handle and the given
+ * index in the bitmap in the device backend. A notification state
+ * is created in hypervisor.
+ */
+static int dbell_link(struct vmci_handle handle, u32 notify_idx)
+{
+	struct vmci_doorbell_link_msg link_msg;
+
+	link_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+					    VMCI_DOORBELL_LINK);
+	link_msg.hdr.src = VMCI_ANON_SRC_HANDLE;
+	link_msg.hdr.payload_size = sizeof(link_msg) - VMCI_DG_HEADERSIZE;
+	link_msg.handle = handle;
+	link_msg.notify_idx = notify_idx;
+
+	return vmci_send_datagram(&link_msg.hdr);
+}
+
+/*
+ * Unlinks the given doorbell handle from an index in the bitmap in
+ * the device backend. The notification state is destroyed in hypervisor.
+ */
+static int dbell_unlink(struct vmci_handle handle)
+{
+	struct vmci_doorbell_unlink_msg unlink_msg;
+
+	unlink_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+					      VMCI_DOORBELL_UNLINK);
+	unlink_msg.hdr.src = VMCI_ANON_SRC_HANDLE;
+	unlink_msg.hdr.payload_size = sizeof(unlink_msg) - VMCI_DG_HEADERSIZE;
+	unlink_msg.handle = handle;
+
+	return vmci_send_datagram(&unlink_msg.hdr);
+}
+
+/*
+ * Notify another guest or the host.  We send a datagram down to the
+ * host via the hypervisor with the notification info.
+ */
+static int dbell_notify_as_guest(struct vmci_handle handle, u32 priv_flags)
+{
+	struct vmci_doorbell_notify_msg notify_msg;
+
+	notify_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+					      VMCI_DOORBELL_NOTIFY);
+	notify_msg.hdr.src = VMCI_ANON_SRC_HANDLE;
+	notify_msg.hdr.payload_size = sizeof(notify_msg) - VMCI_DG_HEADERSIZE;
+	notify_msg.handle = handle;
+
+	return vmci_send_datagram(&notify_msg.hdr);
+}
+
+/*
+ * Calls the specified callback in a delayed context.
+ */
+static void dbell_delayed_dispatch(struct work_struct *work)
+{
+	struct dbell_entry *entry = container_of(work,
+						 struct dbell_entry, work);
+
+	entry->notify_cb(entry->client_data);
+	vmci_resource_put(&entry->resource);
+}
+
+/*
+ * Dispatches a doorbell notification to the host context.
+ */
+int vmci_dbell_host_context_notify(u32 src_cid, struct vmci_handle handle)
+{
+	struct dbell_entry *entry;
+	struct vmci_resource *resource;
+
+	if (vmci_handle_is_invalid(handle)) {
+		pr_devel("Notifying an invalid doorbell (handle=0x%x:0x%x)\n",
+			 handle.context, handle.resource);
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	resource = vmci_resource_by_handle(handle,
+					   VMCI_RESOURCE_TYPE_DOORBELL);
+	if (!resource) {
+		pr_devel("Notifying an unknown doorbell (handle=0x%x:0x%x)\n",
+			 handle.context, handle.resource);
+		return VMCI_ERROR_NOT_FOUND;
+	}
+
+	entry = container_of(resource, struct dbell_entry, resource);
+	if (entry->run_delayed) {
+		if (!schedule_work(&entry->work))
+			vmci_resource_put(resource);
+	} else {
+		entry->notify_cb(entry->client_data);
+		vmci_resource_put(resource);
+	}
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Register the notification bitmap with the host.
+ */
+bool vmci_dbell_register_notification_bitmap(u32 bitmap_ppn)
+{
+	int result;
+	struct vmci_notify_bm_set_msg bitmap_set_msg = { };
+
+	bitmap_set_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+						  VMCI_SET_NOTIFY_BITMAP);
+	bitmap_set_msg.hdr.src = VMCI_ANON_SRC_HANDLE;
+	bitmap_set_msg.hdr.payload_size = sizeof(bitmap_set_msg) -
+	    VMCI_DG_HEADERSIZE;
+	bitmap_set_msg.bitmap_ppn = bitmap_ppn;
+
+	result = vmci_send_datagram(&bitmap_set_msg.hdr);
+	if (result != VMCI_SUCCESS) {
+		pr_devel("Failed to register (PPN=%u) as notification bitmap (error=%d)\n",
+			 bitmap_ppn, result);
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Executes or schedules the handlers for a given notify index.
+ */
+static void dbell_fire_entries(u32 notify_idx)
+{
+	u32 bucket = VMCI_DOORBELL_HASH(notify_idx);
+	struct dbell_entry *dbell;
+
+	spin_lock_bh(&vmci_doorbell_it.lock);
+
+	hlist_for_each_entry(dbell, &vmci_doorbell_it.entries[bucket], node) {
+		if (dbell->idx == notify_idx &&
+		    atomic_read(&dbell->active) == 1) {
+			if (dbell->run_delayed) {
+				vmci_resource_get(&dbell->resource);
+				if (!schedule_work(&dbell->work))
+					vmci_resource_put(&dbell->resource);
+			} else {
+				dbell->notify_cb(dbell->client_data);
+			}
+		}
+	}
+
+	spin_unlock_bh(&vmci_doorbell_it.lock);
+}
+
+/*
+ * Scans the notification bitmap, collects pending notifications,
+ * resets the bitmap and invokes appropriate callbacks.
+ */
+void vmci_dbell_scan_notification_entries(u8 *bitmap)
+{
+	u32 idx;
+
+	for (idx = 0; idx < max_notify_idx; idx++) {
+		if (bitmap[idx] & 0x1) {
+			bitmap[idx] &= ~1;
+			dbell_fire_entries(idx);
+		}
+	}
+}
+
+/*
+ * vmci_doorbell_create() - Creates a doorbell
+ * @handle:     A handle used to track the resource.  Can be invalid.
+ * @flags:      Flag that determines context of callback.
+ * @priv_flags: Privileges flags.
+ * @notify_cb:  The callback to be ivoked when the doorbell fires.
+ * @client_data:        A parameter to be passed to the callback.
+ *
+ * Creates a doorbell with the given callback. If the handle is
+ * VMCI_INVALID_HANDLE, a free handle will be assigned, if
+ * possible. The callback can be run immediately (potentially with
+ * locks held - the default) or delayed (in a kernel thread) by
+ * specifying the flag VMCI_FLAG_DELAYED_CB. If delayed execution
+ * is selected, a given callback may not be run if the kernel is
+ * unable to allocate memory for the delayed execution (highly
+ * unlikely).
+ */
+int vmci_doorbell_create(struct vmci_handle *handle,
+			 u32 flags,
+			 u32 priv_flags,
+			 vmci_callback notify_cb, void *client_data)
+{
+	struct dbell_entry *entry;
+	struct vmci_handle new_handle;
+	int result;
+
+	if (!handle || !notify_cb || flags & ~VMCI_FLAG_DELAYED_CB ||
+	    priv_flags & ~VMCI_PRIVILEGE_ALL_FLAGS)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	if (entry == NULL) {
+		pr_warn("Failed allocating memory for datagram entry\n");
+		return VMCI_ERROR_NO_MEM;
+	}
+
+	if (vmci_handle_is_invalid(*handle)) {
+		u32 context_id = vmci_get_context_id();
+
+		if (context_id == VMCI_INVALID_ID) {
+			pr_warn("Failed to get context ID\n");
+			result = VMCI_ERROR_NO_RESOURCES;
+			goto free_mem;
+		}
+
+		/* Let resource code allocate a free ID for us */
+		new_handle = vmci_make_handle(context_id, VMCI_INVALID_ID);
+	} else {
+		bool valid_context = false;
+
+		/*
+		 * Validate the handle.  We must do both of the checks below
+		 * because we can be acting as both a host and a guest at the
+		 * same time. We always allow the host context ID, since the
+		 * host functionality is in practice always there with the
+		 * unified driver.
+		 */
+		if (handle->context == VMCI_HOST_CONTEXT_ID ||
+		    (vmci_guest_code_active() &&
+		     vmci_get_context_id() == handle->context)) {
+			valid_context = true;
+		}
+
+		if (!valid_context || handle->resource == VMCI_INVALID_ID) {
+			pr_devel("Invalid argument (handle=0x%x:0x%x)\n",
+				 handle->context, handle->resource);
+			result = VMCI_ERROR_INVALID_ARGS;
+			goto free_mem;
+		}
+
+		new_handle = *handle;
+	}
+
+	entry->idx = 0;
+	INIT_HLIST_NODE(&entry->node);
+	entry->priv_flags = priv_flags;
+	INIT_WORK(&entry->work, dbell_delayed_dispatch);
+	entry->run_delayed = flags & VMCI_FLAG_DELAYED_CB;
+	entry->notify_cb = notify_cb;
+	entry->client_data = client_data;
+	atomic_set(&entry->active, 0);
+
+	result = vmci_resource_add(&entry->resource,
+				   VMCI_RESOURCE_TYPE_DOORBELL,
+				   new_handle);
+	if (result != VMCI_SUCCESS) {
+		pr_warn("Failed to add new resource (handle=0x%x:0x%x), error: %d\n",
+			new_handle.context, new_handle.resource, result);
+		goto free_mem;
+	}
+
+	new_handle = vmci_resource_handle(&entry->resource);
+	if (vmci_guest_code_active()) {
+		dbell_index_table_add(entry);
+		result = dbell_link(new_handle, entry->idx);
+		if (VMCI_SUCCESS != result)
+			goto destroy_resource;
+
+		atomic_set(&entry->active, 1);
+	}
+
+	*handle = new_handle;
+
+	return result;
+
+ destroy_resource:
+	dbell_index_table_remove(entry);
+	vmci_resource_remove(&entry->resource);
+ free_mem:
+	kfree(entry);
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_doorbell_create);
+
+/*
+ * vmci_doorbell_destroy() - Destroy a doorbell.
+ * @handle:     The handle tracking the resource.
+ *
+ * Destroys a doorbell previously created with vmcii_doorbell_create. This
+ * operation may block waiting for a callback to finish.
+ */
+int vmci_doorbell_destroy(struct vmci_handle handle)
+{
+	struct dbell_entry *entry;
+	struct vmci_resource *resource;
+
+	if (vmci_handle_is_invalid(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	resource = vmci_resource_by_handle(handle,
+					   VMCI_RESOURCE_TYPE_DOORBELL);
+	if (!resource) {
+		pr_devel("Failed to destroy doorbell (handle=0x%x:0x%x)\n",
+			 handle.context, handle.resource);
+		return VMCI_ERROR_NOT_FOUND;
+	}
+
+	entry = container_of(resource, struct dbell_entry, resource);
+
+	if (!hlist_unhashed(&entry->node)) {
+		int result;
+
+		dbell_index_table_remove(entry);
+
+		result = dbell_unlink(handle);
+		if (VMCI_SUCCESS != result) {
+
+			/*
+			 * The only reason this should fail would be
+			 * an inconsistency between guest and
+			 * hypervisor state, where the guest believes
+			 * it has an active registration whereas the
+			 * hypervisor doesn't. One case where this may
+			 * happen is if a doorbell is unregistered
+			 * following a hibernation at a time where the
+			 * doorbell state hasn't been restored on the
+			 * hypervisor side yet. Since the handle has
+			 * now been removed in the guest, we just
+			 * print a warning and return success.
+			 */
+			pr_devel("Unlink of doorbell (handle=0x%x:0x%x) unknown by hypervisor (error=%d)\n",
+				 handle.context, handle.resource, result);
+		}
+	}
+
+	/*
+	 * Now remove the resource from the table.  It might still be in use
+	 * after this, in a callback or still on the delayed work queue.
+	 */
+	vmci_resource_put(&entry->resource);
+	vmci_resource_remove(&entry->resource);
+
+	kfree(entry);
+
+	return VMCI_SUCCESS;
+}
+EXPORT_SYMBOL_GPL(vmci_doorbell_destroy);
+
+/*
+ * vmci_doorbell_notify() - Ring the doorbell (and hide in the bushes).
+ * @dst:        The handlle identifying the doorbell resource
+ * @priv_flags: Priviledge flags.
+ *
+ * Generates a notification on the doorbell identified by the
+ * handle. For host side generation of notifications, the caller
+ * can specify what the privilege of the calling side is.
+ */
+int vmci_doorbell_notify(struct vmci_handle dst, u32 priv_flags)
+{
+	int retval;
+	enum vmci_route route;
+	struct vmci_handle src;
+
+	if (vmci_handle_is_invalid(dst) ||
+	    (priv_flags & ~VMCI_PRIVILEGE_ALL_FLAGS))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	src = VMCI_INVALID_HANDLE;
+	retval = vmci_route(&src, &dst, false, &route);
+	if (retval < VMCI_SUCCESS)
+		return retval;
+
+	if (VMCI_ROUTE_AS_HOST == route)
+		return vmci_ctx_notify_dbell(VMCI_HOST_CONTEXT_ID,
+					     dst, priv_flags);
+
+	if (VMCI_ROUTE_AS_GUEST == route)
+		return dbell_notify_as_guest(dst, priv_flags);
+
+	pr_warn("Unknown route (%d) for doorbell\n", route);
+	return VMCI_ERROR_DST_UNREACHABLE;
+}
+EXPORT_SYMBOL_GPL(vmci_doorbell_notify);
diff --git a/drivers/misc/vmw_vmci/vmci_doorbell.h b/drivers/misc/vmw_vmci/vmci_doorbell.h
new file mode 100644
index 000000000..e4c0b1748
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_doorbell.h
@@ -0,0 +1,51 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#ifndef VMCI_DOORBELL_H
+#define VMCI_DOORBELL_H
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/types.h>
+
+#include "vmci_driver.h"
+
+/*
+ * VMCINotifyResourceInfo: Used to create and destroy doorbells, and
+ * generate a notification for a doorbell or queue pair.
+ */
+struct vmci_dbell_notify_resource_info {
+	struct vmci_handle handle;
+	u16 resource;
+	u16 action;
+	s32 result;
+};
+
+/*
+ * Structure used for checkpointing the doorbell mappings. It is
+ * written to the checkpoint as is, so changing this structure will
+ * break checkpoint compatibility.
+ */
+struct dbell_cpt_state {
+	struct vmci_handle handle;
+	u64 bitmap_idx;
+};
+
+int vmci_dbell_host_context_notify(u32 src_cid, struct vmci_handle handle);
+int vmci_dbell_get_priv_flags(struct vmci_handle handle, u32 *priv_flags);
+
+bool vmci_dbell_register_notification_bitmap(u32 bitmap_ppn);
+void vmci_dbell_scan_notification_entries(u8 *bitmap);
+
+#endif /* VMCI_DOORBELL_H */
diff --git a/drivers/misc/vmw_vmci/vmci_driver.c b/drivers/misc/vmw_vmci/vmci_driver.c
new file mode 100644
index 000000000..003bfba40
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_driver.c
@@ -0,0 +1,117 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+#include <linux/atomic.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+#include "vmci_driver.h"
+#include "vmci_event.h"
+
+static bool vmci_disable_host;
+module_param_named(disable_host, vmci_disable_host, bool, 0);
+MODULE_PARM_DESC(disable_host,
+		 "Disable driver host personality (default=enabled)");
+
+static bool vmci_disable_guest;
+module_param_named(disable_guest, vmci_disable_guest, bool, 0);
+MODULE_PARM_DESC(disable_guest,
+		 "Disable driver guest personality (default=enabled)");
+
+static bool vmci_guest_personality_initialized;
+static bool vmci_host_personality_initialized;
+
+/*
+ * vmci_get_context_id() - Gets the current context ID.
+ *
+ * Returns the current context ID.  Note that since this is accessed only
+ * from code running in the host, this always returns the host context ID.
+ */
+u32 vmci_get_context_id(void)
+{
+	if (vmci_guest_code_active())
+		return vmci_get_vm_context_id();
+	else if (vmci_host_code_active())
+		return VMCI_HOST_CONTEXT_ID;
+
+	return VMCI_INVALID_ID;
+}
+EXPORT_SYMBOL_GPL(vmci_get_context_id);
+
+static int __init vmci_drv_init(void)
+{
+	int vmci_err;
+	int error;
+
+	vmci_err = vmci_event_init();
+	if (vmci_err < VMCI_SUCCESS) {
+		pr_err("Failed to initialize VMCIEvent (result=%d)\n",
+		       vmci_err);
+		return -EINVAL;
+	}
+
+	if (!vmci_disable_guest) {
+		error = vmci_guest_init();
+		if (error) {
+			pr_warn("Failed to initialize guest personality (err=%d)\n",
+				error);
+		} else {
+			vmci_guest_personality_initialized = true;
+			pr_info("Guest personality initialized and is %s\n",
+				vmci_guest_code_active() ?
+				"active" : "inactive");
+		}
+	}
+
+	if (!vmci_disable_host) {
+		error = vmci_host_init();
+		if (error) {
+			pr_warn("Unable to initialize host personality (err=%d)\n",
+				error);
+		} else {
+			vmci_host_personality_initialized = true;
+			pr_info("Initialized host personality\n");
+		}
+	}
+
+	if (!vmci_guest_personality_initialized &&
+	    !vmci_host_personality_initialized) {
+		vmci_event_exit();
+		return -ENODEV;
+	}
+
+	return 0;
+}
+module_init(vmci_drv_init);
+
+static void __exit vmci_drv_exit(void)
+{
+	if (vmci_guest_personality_initialized)
+		vmci_guest_exit();
+
+	if (vmci_host_personality_initialized)
+		vmci_host_exit();
+
+	vmci_event_exit();
+}
+module_exit(vmci_drv_exit);
+
+MODULE_AUTHOR("VMware, Inc.");
+MODULE_DESCRIPTION("VMware Virtual Machine Communication Interface.");
+MODULE_VERSION("1.1.6.0-k");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/misc/vmw_vmci/vmci_driver.h b/drivers/misc/vmw_vmci/vmci_driver.h
new file mode 100644
index 000000000..cee9e977d
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_driver.h
@@ -0,0 +1,57 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#ifndef _VMCI_DRIVER_H_
+#define _VMCI_DRIVER_H_
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/wait.h>
+
+#include "vmci_queue_pair.h"
+#include "vmci_context.h"
+
+enum vmci_obj_type {
+	VMCIOBJ_VMX_VM = 10,
+	VMCIOBJ_CONTEXT,
+	VMCIOBJ_SOCKET,
+	VMCIOBJ_NOT_SET,
+};
+
+/* For storing VMCI structures in file handles. */
+struct vmci_obj {
+	void *ptr;
+	enum vmci_obj_type type;
+};
+
+/*
+ * Needed by other components of this module.  It's okay to have one global
+ * instance of this because there can only ever be one VMCI device.  Our
+ * virtual hardware enforces this.
+ */
+extern struct pci_dev *vmci_pdev;
+
+u32 vmci_get_context_id(void);
+int vmci_send_datagram(struct vmci_datagram *dg);
+
+int vmci_host_init(void);
+void vmci_host_exit(void);
+bool vmci_host_code_active(void);
+
+int vmci_guest_init(void);
+void vmci_guest_exit(void);
+bool vmci_guest_code_active(void);
+u32 vmci_get_vm_context_id(void);
+
+#endif /* _VMCI_DRIVER_H_ */
diff --git a/drivers/misc/vmw_vmci/vmci_event.c b/drivers/misc/vmw_vmci/vmci_event.c
new file mode 100644
index 000000000..84258a480
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_event.c
@@ -0,0 +1,225 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/rculist.h>
+
+#include "vmci_driver.h"
+#include "vmci_event.h"
+
+#define EVENT_MAGIC 0xEABE0000
+#define VMCI_EVENT_MAX_ATTEMPTS 10
+
+struct vmci_subscription {
+	u32 id;
+	u32 event;
+	vmci_event_cb callback;
+	void *callback_data;
+	struct list_head node;	/* on one of subscriber lists */
+};
+
+static struct list_head subscriber_array[VMCI_EVENT_MAX];
+static DEFINE_MUTEX(subscriber_mutex);
+
+int __init vmci_event_init(void)
+{
+	int i;
+
+	for (i = 0; i < VMCI_EVENT_MAX; i++)
+		INIT_LIST_HEAD(&subscriber_array[i]);
+
+	return VMCI_SUCCESS;
+}
+
+void vmci_event_exit(void)
+{
+	int e;
+
+	/* We free all memory at exit. */
+	for (e = 0; e < VMCI_EVENT_MAX; e++) {
+		struct vmci_subscription *cur, *p2;
+		list_for_each_entry_safe(cur, p2, &subscriber_array[e], node) {
+
+			/*
+			 * We should never get here because all events
+			 * should have been unregistered before we try
+			 * to unload the driver module.
+			 */
+			pr_warn("Unexpected free events occurring\n");
+			list_del(&cur->node);
+			kfree(cur);
+		}
+	}
+}
+
+/*
+ * Find entry. Assumes subscriber_mutex is held.
+ */
+static struct vmci_subscription *event_find(u32 sub_id)
+{
+	int e;
+
+	for (e = 0; e < VMCI_EVENT_MAX; e++) {
+		struct vmci_subscription *cur;
+		list_for_each_entry(cur, &subscriber_array[e], node) {
+			if (cur->id == sub_id)
+				return cur;
+		}
+	}
+	return NULL;
+}
+
+/*
+ * Actually delivers the events to the subscribers.
+ * The callback function for each subscriber is invoked.
+ */
+static void event_deliver(struct vmci_event_msg *event_msg)
+{
+	struct vmci_subscription *cur;
+	struct list_head *subscriber_list;
+
+	rcu_read_lock();
+	subscriber_list = &subscriber_array[event_msg->event_data.event];
+	list_for_each_entry_rcu(cur, subscriber_list, node) {
+		cur->callback(cur->id, &event_msg->event_data,
+			      cur->callback_data);
+	}
+	rcu_read_unlock();
+}
+
+/*
+ * Dispatcher for the VMCI_EVENT_RECEIVE datagrams. Calls all
+ * subscribers for given event.
+ */
+int vmci_event_dispatch(struct vmci_datagram *msg)
+{
+	struct vmci_event_msg *event_msg = (struct vmci_event_msg *)msg;
+
+	if (msg->payload_size < sizeof(u32) ||
+	    msg->payload_size > sizeof(struct vmci_event_data_max))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	if (!VMCI_EVENT_VALID(event_msg->event_data.event))
+		return VMCI_ERROR_EVENT_UNKNOWN;
+
+	event_deliver(event_msg);
+	return VMCI_SUCCESS;
+}
+
+/*
+ * vmci_event_subscribe() - Subscribe to a given event.
+ * @event:      The event to subscribe to.
+ * @callback:   The callback to invoke upon the event.
+ * @callback_data:      Data to pass to the callback.
+ * @subscription_id:    ID used to track subscription.  Used with
+ *              vmci_event_unsubscribe()
+ *
+ * Subscribes to the provided event. The callback specified will be
+ * fired from RCU critical section and therefore must not sleep.
+ */
+int vmci_event_subscribe(u32 event,
+			 vmci_event_cb callback,
+			 void *callback_data,
+			 u32 *new_subscription_id)
+{
+	struct vmci_subscription *sub;
+	int attempts;
+	int retval;
+	bool have_new_id = false;
+
+	if (!new_subscription_id) {
+		pr_devel("%s: Invalid subscription (NULL)\n", __func__);
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	if (!VMCI_EVENT_VALID(event) || !callback) {
+		pr_devel("%s: Failed to subscribe to event (type=%d) (callback=%p) (data=%p)\n",
+			 __func__, event, callback, callback_data);
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	sub = kzalloc(sizeof(*sub), GFP_KERNEL);
+	if (!sub)
+		return VMCI_ERROR_NO_MEM;
+
+	sub->id = VMCI_EVENT_MAX;
+	sub->event = event;
+	sub->callback = callback;
+	sub->callback_data = callback_data;
+	INIT_LIST_HEAD(&sub->node);
+
+	mutex_lock(&subscriber_mutex);
+
+	/* Creation of a new event is always allowed. */
+	for (attempts = 0; attempts < VMCI_EVENT_MAX_ATTEMPTS; attempts++) {
+		static u32 subscription_id;
+		/*
+		 * We try to get an id a couple of time before
+		 * claiming we are out of resources.
+		 */
+
+		/* Test for duplicate id. */
+		if (!event_find(++subscription_id)) {
+			sub->id = subscription_id;
+			have_new_id = true;
+			break;
+		}
+	}
+
+	if (have_new_id) {
+		list_add_rcu(&sub->node, &subscriber_array[event]);
+		retval = VMCI_SUCCESS;
+	} else {
+		retval = VMCI_ERROR_NO_RESOURCES;
+	}
+
+	mutex_unlock(&subscriber_mutex);
+
+	*new_subscription_id = sub->id;
+	return retval;
+}
+EXPORT_SYMBOL_GPL(vmci_event_subscribe);
+
+/*
+ * vmci_event_unsubscribe() - unsubscribe from an event.
+ * @sub_id:     A subscription ID as provided by vmci_event_subscribe()
+ *
+ * Unsubscribe from given event. Removes it from list and frees it.
+ * Will return callback_data if requested by caller.
+ */
+int vmci_event_unsubscribe(u32 sub_id)
+{
+	struct vmci_subscription *s;
+
+	mutex_lock(&subscriber_mutex);
+	s = event_find(sub_id);
+	if (s)
+		list_del_rcu(&s->node);
+	mutex_unlock(&subscriber_mutex);
+
+	if (!s)
+		return VMCI_ERROR_NOT_FOUND;
+
+	synchronize_rcu();
+	kfree(s);
+
+	return VMCI_SUCCESS;
+}
+EXPORT_SYMBOL_GPL(vmci_event_unsubscribe);
diff --git a/drivers/misc/vmw_vmci/vmci_event.h b/drivers/misc/vmw_vmci/vmci_event.h
new file mode 100644
index 000000000..7df9b1c0a
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_event.h
@@ -0,0 +1,25 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#ifndef __VMCI_EVENT_H__
+#define __VMCI_EVENT_H__
+
+#include <linux/vmw_vmci_api.h>
+
+int vmci_event_init(void);
+void vmci_event_exit(void);
+int vmci_event_dispatch(struct vmci_datagram *msg);
+
+#endif /*__VMCI_EVENT_H__ */
diff --git a/drivers/misc/vmw_vmci/vmci_guest.c b/drivers/misc/vmw_vmci/vmci_guest.c
new file mode 100644
index 000000000..dd20ea4ad
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_guest.c
@@ -0,0 +1,736 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+#include <linux/moduleparam.h>
+#include <linux/interrupt.h>
+#include <linux/highmem.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <linux/smp.h>
+#include <linux/io.h>
+#include <linux/vmalloc.h>
+
+#include "vmci_datagram.h"
+#include "vmci_doorbell.h"
+#include "vmci_context.h"
+#include "vmci_driver.h"
+#include "vmci_event.h"
+
+#define PCI_DEVICE_ID_VMWARE_VMCI	0x0740
+
+#define VMCI_UTIL_NUM_RESOURCES 1
+
+static bool vmci_disable_msi;
+module_param_named(disable_msi, vmci_disable_msi, bool, 0);
+MODULE_PARM_DESC(disable_msi, "Disable MSI use in driver - (default=0)");
+
+static bool vmci_disable_msix;
+module_param_named(disable_msix, vmci_disable_msix, bool, 0);
+MODULE_PARM_DESC(disable_msix, "Disable MSI-X use in driver - (default=0)");
+
+static u32 ctx_update_sub_id = VMCI_INVALID_ID;
+static u32 vm_context_id = VMCI_INVALID_ID;
+
+struct vmci_guest_device {
+	struct device *dev;	/* PCI device we are attached to */
+	void __iomem *iobase;
+
+	bool exclusive_vectors;
+
+	struct tasklet_struct datagram_tasklet;
+	struct tasklet_struct bm_tasklet;
+
+	void *data_buffer;
+	void *notification_bitmap;
+	dma_addr_t notification_base;
+};
+
+/* vmci_dev singleton device and supporting data*/
+struct pci_dev *vmci_pdev;
+static struct vmci_guest_device *vmci_dev_g;
+static DEFINE_SPINLOCK(vmci_dev_spinlock);
+
+static atomic_t vmci_num_guest_devices = ATOMIC_INIT(0);
+
+bool vmci_guest_code_active(void)
+{
+	return atomic_read(&vmci_num_guest_devices) != 0;
+}
+
+u32 vmci_get_vm_context_id(void)
+{
+	if (vm_context_id == VMCI_INVALID_ID) {
+		struct vmci_datagram get_cid_msg;
+		get_cid_msg.dst =
+		    vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+				     VMCI_GET_CONTEXT_ID);
+		get_cid_msg.src = VMCI_ANON_SRC_HANDLE;
+		get_cid_msg.payload_size = 0;
+		vm_context_id = vmci_send_datagram(&get_cid_msg);
+	}
+	return vm_context_id;
+}
+
+/*
+ * VM to hypervisor call mechanism. We use the standard VMware naming
+ * convention since shared code is calling this function as well.
+ */
+int vmci_send_datagram(struct vmci_datagram *dg)
+{
+	unsigned long flags;
+	int result;
+
+	/* Check args. */
+	if (dg == NULL)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	/*
+	 * Need to acquire spinlock on the device because the datagram
+	 * data may be spread over multiple pages and the monitor may
+	 * interleave device user rpc calls from multiple
+	 * VCPUs. Acquiring the spinlock precludes that
+	 * possibility. Disabling interrupts to avoid incoming
+	 * datagrams during a "rep out" and possibly landing up in
+	 * this function.
+	 */
+	spin_lock_irqsave(&vmci_dev_spinlock, flags);
+
+	if (vmci_dev_g) {
+		iowrite8_rep(vmci_dev_g->iobase + VMCI_DATA_OUT_ADDR,
+			     dg, VMCI_DG_SIZE(dg));
+		result = ioread32(vmci_dev_g->iobase + VMCI_RESULT_LOW_ADDR);
+	} else {
+		result = VMCI_ERROR_UNAVAILABLE;
+	}
+
+	spin_unlock_irqrestore(&vmci_dev_spinlock, flags);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_send_datagram);
+
+/*
+ * Gets called with the new context id if updated or resumed.
+ * Context id.
+ */
+static void vmci_guest_cid_update(u32 sub_id,
+				  const struct vmci_event_data *event_data,
+				  void *client_data)
+{
+	const struct vmci_event_payld_ctx *ev_payload =
+				vmci_event_data_const_payload(event_data);
+
+	if (sub_id != ctx_update_sub_id) {
+		pr_devel("Invalid subscriber (ID=0x%x)\n", sub_id);
+		return;
+	}
+
+	if (!event_data || ev_payload->context_id == VMCI_INVALID_ID) {
+		pr_devel("Invalid event data\n");
+		return;
+	}
+
+	pr_devel("Updating context from (ID=0x%x) to (ID=0x%x) on event (type=%d)\n",
+		 vm_context_id, ev_payload->context_id, event_data->event);
+
+	vm_context_id = ev_payload->context_id;
+}
+
+/*
+ * Verify that the host supports the hypercalls we need. If it does not,
+ * try to find fallback hypercalls and use those instead.  Returns
+ * true if required hypercalls (or fallback hypercalls) are
+ * supported by the host, false otherwise.
+ */
+static int vmci_check_host_caps(struct pci_dev *pdev)
+{
+	bool result;
+	struct vmci_resource_query_msg *msg;
+	u32 msg_size = sizeof(struct vmci_resource_query_hdr) +
+				VMCI_UTIL_NUM_RESOURCES * sizeof(u32);
+	struct vmci_datagram *check_msg;
+
+	check_msg = kzalloc(msg_size, GFP_KERNEL);
+	if (!check_msg) {
+		dev_err(&pdev->dev, "%s: Insufficient memory\n", __func__);
+		return -ENOMEM;
+	}
+
+	check_msg->dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+					  VMCI_RESOURCES_QUERY);
+	check_msg->src = VMCI_ANON_SRC_HANDLE;
+	check_msg->payload_size = msg_size - VMCI_DG_HEADERSIZE;
+	msg = (struct vmci_resource_query_msg *)VMCI_DG_PAYLOAD(check_msg);
+
+	msg->num_resources = VMCI_UTIL_NUM_RESOURCES;
+	msg->resources[0] = VMCI_GET_CONTEXT_ID;
+
+	/* Checks that hyper calls are supported */
+	result = vmci_send_datagram(check_msg) == 0x01;
+	kfree(check_msg);
+
+	dev_dbg(&pdev->dev, "%s: Host capability check: %s\n",
+		__func__, result ? "PASSED" : "FAILED");
+
+	/* We need the vector. There are no fallbacks. */
+	return result ? 0 : -ENXIO;
+}
+
+/*
+ * Reads datagrams from the data in port and dispatches them. We
+ * always start reading datagrams into only the first page of the
+ * datagram buffer. If the datagrams don't fit into one page, we
+ * use the maximum datagram buffer size for the remainder of the
+ * invocation. This is a simple heuristic for not penalizing
+ * small datagrams.
+ *
+ * This function assumes that it has exclusive access to the data
+ * in port for the duration of the call.
+ */
+static void vmci_dispatch_dgs(unsigned long data)
+{
+	struct vmci_guest_device *vmci_dev = (struct vmci_guest_device *)data;
+	u8 *dg_in_buffer = vmci_dev->data_buffer;
+	struct vmci_datagram *dg;
+	size_t dg_in_buffer_size = VMCI_MAX_DG_SIZE;
+	size_t current_dg_in_buffer_size = PAGE_SIZE;
+	size_t remaining_bytes;
+
+	BUILD_BUG_ON(VMCI_MAX_DG_SIZE < PAGE_SIZE);
+
+	ioread8_rep(vmci_dev->iobase + VMCI_DATA_IN_ADDR,
+		    vmci_dev->data_buffer, current_dg_in_buffer_size);
+	dg = (struct vmci_datagram *)dg_in_buffer;
+	remaining_bytes = current_dg_in_buffer_size;
+
+	while (dg->dst.resource != VMCI_INVALID_ID ||
+	       remaining_bytes > PAGE_SIZE) {
+		unsigned dg_in_size;
+
+		/*
+		 * When the input buffer spans multiple pages, a datagram can
+		 * start on any page boundary in the buffer.
+		 */
+		if (dg->dst.resource == VMCI_INVALID_ID) {
+			dg = (struct vmci_datagram *)roundup(
+				(uintptr_t)dg + 1, PAGE_SIZE);
+			remaining_bytes =
+				(size_t)(dg_in_buffer +
+					 current_dg_in_buffer_size -
+					 (u8 *)dg);
+			continue;
+		}
+
+		dg_in_size = VMCI_DG_SIZE_ALIGNED(dg);
+
+		if (dg_in_size <= dg_in_buffer_size) {
+			int result;
+
+			/*
+			 * If the remaining bytes in the datagram
+			 * buffer doesn't contain the complete
+			 * datagram, we first make sure we have enough
+			 * room for it and then we read the reminder
+			 * of the datagram and possibly any following
+			 * datagrams.
+			 */
+			if (dg_in_size > remaining_bytes) {
+				if (remaining_bytes !=
+				    current_dg_in_buffer_size) {
+
+					/*
+					 * We move the partial
+					 * datagram to the front and
+					 * read the reminder of the
+					 * datagram and possibly
+					 * following calls into the
+					 * following bytes.
+					 */
+					memmove(dg_in_buffer, dg_in_buffer +
+						current_dg_in_buffer_size -
+						remaining_bytes,
+						remaining_bytes);
+					dg = (struct vmci_datagram *)
+					    dg_in_buffer;
+				}
+
+				if (current_dg_in_buffer_size !=
+				    dg_in_buffer_size)
+					current_dg_in_buffer_size =
+					    dg_in_buffer_size;
+
+				ioread8_rep(vmci_dev->iobase +
+						VMCI_DATA_IN_ADDR,
+					vmci_dev->data_buffer +
+						remaining_bytes,
+					current_dg_in_buffer_size -
+						remaining_bytes);
+			}
+
+			/*
+			 * We special case event datagrams from the
+			 * hypervisor.
+			 */
+			if (dg->src.context == VMCI_HYPERVISOR_CONTEXT_ID &&
+			    dg->dst.resource == VMCI_EVENT_HANDLER) {
+				result = vmci_event_dispatch(dg);
+			} else {
+				result = vmci_datagram_invoke_guest_handler(dg);
+			}
+			if (result < VMCI_SUCCESS)
+				dev_dbg(vmci_dev->dev,
+					"Datagram with resource (ID=0x%x) failed (err=%d)\n",
+					 dg->dst.resource, result);
+
+			/* On to the next datagram. */
+			dg = (struct vmci_datagram *)((u8 *)dg +
+						      dg_in_size);
+		} else {
+			size_t bytes_to_skip;
+
+			/*
+			 * Datagram doesn't fit in datagram buffer of maximal
+			 * size. We drop it.
+			 */
+			dev_dbg(vmci_dev->dev,
+				"Failed to receive datagram (size=%u bytes)\n",
+				 dg_in_size);
+
+			bytes_to_skip = dg_in_size - remaining_bytes;
+			if (current_dg_in_buffer_size != dg_in_buffer_size)
+				current_dg_in_buffer_size = dg_in_buffer_size;
+
+			for (;;) {
+				ioread8_rep(vmci_dev->iobase +
+						VMCI_DATA_IN_ADDR,
+					vmci_dev->data_buffer,
+					current_dg_in_buffer_size);
+				if (bytes_to_skip <= current_dg_in_buffer_size)
+					break;
+
+				bytes_to_skip -= current_dg_in_buffer_size;
+			}
+			dg = (struct vmci_datagram *)(dg_in_buffer +
+						      bytes_to_skip);
+		}
+
+		remaining_bytes =
+		    (size_t) (dg_in_buffer + current_dg_in_buffer_size -
+			      (u8 *)dg);
+
+		if (remaining_bytes < VMCI_DG_HEADERSIZE) {
+			/* Get the next batch of datagrams. */
+
+			ioread8_rep(vmci_dev->iobase + VMCI_DATA_IN_ADDR,
+				    vmci_dev->data_buffer,
+				    current_dg_in_buffer_size);
+			dg = (struct vmci_datagram *)dg_in_buffer;
+			remaining_bytes = current_dg_in_buffer_size;
+		}
+	}
+}
+
+/*
+ * Scans the notification bitmap for raised flags, clears them
+ * and handles the notifications.
+ */
+static void vmci_process_bitmap(unsigned long data)
+{
+	struct vmci_guest_device *dev = (struct vmci_guest_device *)data;
+
+	if (!dev->notification_bitmap) {
+		dev_dbg(dev->dev, "No bitmap present in %s\n", __func__);
+		return;
+	}
+
+	vmci_dbell_scan_notification_entries(dev->notification_bitmap);
+}
+
+/*
+ * Interrupt handler for legacy or MSI interrupt, or for first MSI-X
+ * interrupt (vector VMCI_INTR_DATAGRAM).
+ */
+static irqreturn_t vmci_interrupt(int irq, void *_dev)
+{
+	struct vmci_guest_device *dev = _dev;
+
+	/*
+	 * If we are using MSI-X with exclusive vectors then we simply schedule
+	 * the datagram tasklet, since we know the interrupt was meant for us.
+	 * Otherwise we must read the ICR to determine what to do.
+	 */
+
+	if (dev->exclusive_vectors) {
+		tasklet_schedule(&dev->datagram_tasklet);
+	} else {
+		unsigned int icr;
+
+		/* Acknowledge interrupt and determine what needs doing. */
+		icr = ioread32(dev->iobase + VMCI_ICR_ADDR);
+		if (icr == 0 || icr == ~0)
+			return IRQ_NONE;
+
+		if (icr & VMCI_ICR_DATAGRAM) {
+			tasklet_schedule(&dev->datagram_tasklet);
+			icr &= ~VMCI_ICR_DATAGRAM;
+		}
+
+		if (icr & VMCI_ICR_NOTIFICATION) {
+			tasklet_schedule(&dev->bm_tasklet);
+			icr &= ~VMCI_ICR_NOTIFICATION;
+		}
+
+		if (icr != 0)
+			dev_warn(dev->dev,
+				 "Ignoring unknown interrupt cause (%d)\n",
+				 icr);
+	}
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Interrupt handler for MSI-X interrupt vector VMCI_INTR_NOTIFICATION,
+ * which is for the notification bitmap.  Will only get called if we are
+ * using MSI-X with exclusive vectors.
+ */
+static irqreturn_t vmci_interrupt_bm(int irq, void *_dev)
+{
+	struct vmci_guest_device *dev = _dev;
+
+	/* For MSI-X we can just assume it was meant for us. */
+	tasklet_schedule(&dev->bm_tasklet);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Most of the initialization at module load time is done here.
+ */
+static int vmci_guest_probe_device(struct pci_dev *pdev,
+				   const struct pci_device_id *id)
+{
+	struct vmci_guest_device *vmci_dev;
+	void __iomem *iobase;
+	unsigned int capabilities;
+	unsigned long cmd;
+	int vmci_err;
+	int error;
+
+	dev_dbg(&pdev->dev, "Probing for vmci/PCI guest device\n");
+
+	error = pcim_enable_device(pdev);
+	if (error) {
+		dev_err(&pdev->dev,
+			"Failed to enable VMCI device: %d\n", error);
+		return error;
+	}
+
+	error = pcim_iomap_regions(pdev, 1 << 0, KBUILD_MODNAME);
+	if (error) {
+		dev_err(&pdev->dev, "Failed to reserve/map IO regions\n");
+		return error;
+	}
+
+	iobase = pcim_iomap_table(pdev)[0];
+
+	dev_info(&pdev->dev, "Found VMCI PCI device at %#lx, irq %u\n",
+		 (unsigned long)iobase, pdev->irq);
+
+	vmci_dev = devm_kzalloc(&pdev->dev, sizeof(*vmci_dev), GFP_KERNEL);
+	if (!vmci_dev) {
+		dev_err(&pdev->dev,
+			"Can't allocate memory for VMCI device\n");
+		return -ENOMEM;
+	}
+
+	vmci_dev->dev = &pdev->dev;
+	vmci_dev->exclusive_vectors = false;
+	vmci_dev->iobase = iobase;
+
+	tasklet_init(&vmci_dev->datagram_tasklet,
+		     vmci_dispatch_dgs, (unsigned long)vmci_dev);
+	tasklet_init(&vmci_dev->bm_tasklet,
+		     vmci_process_bitmap, (unsigned long)vmci_dev);
+
+	vmci_dev->data_buffer = vmalloc(VMCI_MAX_DG_SIZE);
+	if (!vmci_dev->data_buffer) {
+		dev_err(&pdev->dev,
+			"Can't allocate memory for datagram buffer\n");
+		return -ENOMEM;
+	}
+
+	pci_set_master(pdev);	/* To enable queue_pair functionality. */
+
+	/*
+	 * Verify that the VMCI Device supports the capabilities that
+	 * we need. If the device is missing capabilities that we would
+	 * like to use, check for fallback capabilities and use those
+	 * instead (so we can run a new VM on old hosts). Fail the load if
+	 * a required capability is missing and there is no fallback.
+	 *
+	 * Right now, we need datagrams. There are no fallbacks.
+	 */
+	capabilities = ioread32(vmci_dev->iobase + VMCI_CAPS_ADDR);
+	if (!(capabilities & VMCI_CAPS_DATAGRAM)) {
+		dev_err(&pdev->dev, "Device does not support datagrams\n");
+		error = -ENXIO;
+		goto err_free_data_buffer;
+	}
+
+	/*
+	 * If the hardware supports notifications, we will use that as
+	 * well.
+	 */
+	if (capabilities & VMCI_CAPS_NOTIFICATIONS) {
+		vmci_dev->notification_bitmap = dma_alloc_coherent(
+			&pdev->dev, PAGE_SIZE, &vmci_dev->notification_base,
+			GFP_KERNEL);
+		if (!vmci_dev->notification_bitmap) {
+			dev_warn(&pdev->dev,
+				 "Unable to allocate notification bitmap\n");
+		} else {
+			memset(vmci_dev->notification_bitmap, 0, PAGE_SIZE);
+			capabilities |= VMCI_CAPS_NOTIFICATIONS;
+		}
+	}
+
+	dev_info(&pdev->dev, "Using capabilities 0x%x\n", capabilities);
+
+	/* Let the host know which capabilities we intend to use. */
+	iowrite32(capabilities, vmci_dev->iobase + VMCI_CAPS_ADDR);
+
+	/* Set up global device so that we can start sending datagrams */
+	spin_lock_irq(&vmci_dev_spinlock);
+	vmci_dev_g = vmci_dev;
+	vmci_pdev = pdev;
+	spin_unlock_irq(&vmci_dev_spinlock);
+
+	/*
+	 * Register notification bitmap with device if that capability is
+	 * used.
+	 */
+	if (capabilities & VMCI_CAPS_NOTIFICATIONS) {
+		unsigned long bitmap_ppn =
+			vmci_dev->notification_base >> PAGE_SHIFT;
+		if (!vmci_dbell_register_notification_bitmap(bitmap_ppn)) {
+			dev_warn(&pdev->dev,
+				 "VMCI device unable to register notification bitmap with PPN 0x%x\n",
+				 (u32) bitmap_ppn);
+			error = -ENXIO;
+			goto err_remove_vmci_dev_g;
+		}
+	}
+
+	/* Check host capabilities. */
+	error = vmci_check_host_caps(pdev);
+	if (error)
+		goto err_remove_bitmap;
+
+	/* Enable device. */
+
+	/*
+	 * We subscribe to the VMCI_EVENT_CTX_ID_UPDATE here so we can
+	 * update the internal context id when needed.
+	 */
+	vmci_err = vmci_event_subscribe(VMCI_EVENT_CTX_ID_UPDATE,
+					vmci_guest_cid_update, NULL,
+					&ctx_update_sub_id);
+	if (vmci_err < VMCI_SUCCESS)
+		dev_warn(&pdev->dev,
+			 "Failed to subscribe to event (type=%d): %d\n",
+			 VMCI_EVENT_CTX_ID_UPDATE, vmci_err);
+
+	/*
+	 * Enable interrupts.  Try MSI-X first, then MSI, and then fallback on
+	 * legacy interrupts.
+	 */
+	error = pci_alloc_irq_vectors(pdev, VMCI_MAX_INTRS, VMCI_MAX_INTRS,
+			PCI_IRQ_MSIX);
+	if (error < 0) {
+		error = pci_alloc_irq_vectors(pdev, 1, 1,
+				PCI_IRQ_MSIX | PCI_IRQ_MSI | PCI_IRQ_LEGACY);
+		if (error < 0)
+			goto err_remove_bitmap;
+	} else {
+		vmci_dev->exclusive_vectors = true;
+	}
+
+	/*
+	 * Request IRQ for legacy or MSI interrupts, or for first
+	 * MSI-X vector.
+	 */
+	error = request_irq(pci_irq_vector(pdev, 0), vmci_interrupt,
+			    IRQF_SHARED, KBUILD_MODNAME, vmci_dev);
+	if (error) {
+		dev_err(&pdev->dev, "Irq %u in use: %d\n",
+			pci_irq_vector(pdev, 0), error);
+		goto err_disable_msi;
+	}
+
+	/*
+	 * For MSI-X with exclusive vectors we need to request an
+	 * interrupt for each vector so that we get a separate
+	 * interrupt handler routine.  This allows us to distinguish
+	 * between the vectors.
+	 */
+	if (vmci_dev->exclusive_vectors) {
+		error = request_irq(pci_irq_vector(pdev, 1),
+				    vmci_interrupt_bm, 0, KBUILD_MODNAME,
+				    vmci_dev);
+		if (error) {
+			dev_err(&pdev->dev,
+				"Failed to allocate irq %u: %d\n",
+				pci_irq_vector(pdev, 1), error);
+			goto err_free_irq;
+		}
+	}
+
+	dev_dbg(&pdev->dev, "Registered device\n");
+
+	atomic_inc(&vmci_num_guest_devices);
+
+	/* Enable specific interrupt bits. */
+	cmd = VMCI_IMR_DATAGRAM;
+	if (capabilities & VMCI_CAPS_NOTIFICATIONS)
+		cmd |= VMCI_IMR_NOTIFICATION;
+	iowrite32(cmd, vmci_dev->iobase + VMCI_IMR_ADDR);
+
+	/* Enable interrupts. */
+	iowrite32(VMCI_CONTROL_INT_ENABLE,
+		  vmci_dev->iobase + VMCI_CONTROL_ADDR);
+
+	pci_set_drvdata(pdev, vmci_dev);
+	return 0;
+
+err_free_irq:
+	free_irq(pci_irq_vector(pdev, 0), vmci_dev);
+	tasklet_kill(&vmci_dev->datagram_tasklet);
+	tasklet_kill(&vmci_dev->bm_tasklet);
+
+err_disable_msi:
+	pci_free_irq_vectors(pdev);
+
+	vmci_err = vmci_event_unsubscribe(ctx_update_sub_id);
+	if (vmci_err < VMCI_SUCCESS)
+		dev_warn(&pdev->dev,
+			 "Failed to unsubscribe from event (type=%d) with subscriber (ID=0x%x): %d\n",
+			 VMCI_EVENT_CTX_ID_UPDATE, ctx_update_sub_id, vmci_err);
+
+err_remove_bitmap:
+	if (vmci_dev->notification_bitmap) {
+		iowrite32(VMCI_CONTROL_RESET,
+			  vmci_dev->iobase + VMCI_CONTROL_ADDR);
+		dma_free_coherent(&pdev->dev, PAGE_SIZE,
+				  vmci_dev->notification_bitmap,
+				  vmci_dev->notification_base);
+	}
+
+err_remove_vmci_dev_g:
+	spin_lock_irq(&vmci_dev_spinlock);
+	vmci_pdev = NULL;
+	vmci_dev_g = NULL;
+	spin_unlock_irq(&vmci_dev_spinlock);
+
+err_free_data_buffer:
+	vfree(vmci_dev->data_buffer);
+
+	/* The rest are managed resources and will be freed by PCI core */
+	return error;
+}
+
+static void vmci_guest_remove_device(struct pci_dev *pdev)
+{
+	struct vmci_guest_device *vmci_dev = pci_get_drvdata(pdev);
+	int vmci_err;
+
+	dev_dbg(&pdev->dev, "Removing device\n");
+
+	atomic_dec(&vmci_num_guest_devices);
+
+	vmci_qp_guest_endpoints_exit();
+
+	vmci_err = vmci_event_unsubscribe(ctx_update_sub_id);
+	if (vmci_err < VMCI_SUCCESS)
+		dev_warn(&pdev->dev,
+			 "Failed to unsubscribe from event (type=%d) with subscriber (ID=0x%x): %d\n",
+			 VMCI_EVENT_CTX_ID_UPDATE, ctx_update_sub_id, vmci_err);
+
+	spin_lock_irq(&vmci_dev_spinlock);
+	vmci_dev_g = NULL;
+	vmci_pdev = NULL;
+	spin_unlock_irq(&vmci_dev_spinlock);
+
+	dev_dbg(&pdev->dev, "Resetting vmci device\n");
+	iowrite32(VMCI_CONTROL_RESET, vmci_dev->iobase + VMCI_CONTROL_ADDR);
+
+	/*
+	 * Free IRQ and then disable MSI/MSI-X as appropriate.  For
+	 * MSI-X, we might have multiple vectors, each with their own
+	 * IRQ, which we must free too.
+	 */
+	if (vmci_dev->exclusive_vectors)
+		free_irq(pci_irq_vector(pdev, 1), vmci_dev);
+	free_irq(pci_irq_vector(pdev, 0), vmci_dev);
+	pci_free_irq_vectors(pdev);
+
+	tasklet_kill(&vmci_dev->datagram_tasklet);
+	tasklet_kill(&vmci_dev->bm_tasklet);
+
+	if (vmci_dev->notification_bitmap) {
+		/*
+		 * The device reset above cleared the bitmap state of the
+		 * device, so we can safely free it here.
+		 */
+
+		dma_free_coherent(&pdev->dev, PAGE_SIZE,
+				  vmci_dev->notification_bitmap,
+				  vmci_dev->notification_base);
+	}
+
+	vfree(vmci_dev->data_buffer);
+
+	/* The rest are managed resources and will be freed by PCI core */
+}
+
+static const struct pci_device_id vmci_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_VMWARE, PCI_DEVICE_ID_VMWARE_VMCI), },
+	{ 0 },
+};
+MODULE_DEVICE_TABLE(pci, vmci_ids);
+
+static struct pci_driver vmci_guest_driver = {
+	.name		= KBUILD_MODNAME,
+	.id_table	= vmci_ids,
+	.probe		= vmci_guest_probe_device,
+	.remove		= vmci_guest_remove_device,
+};
+
+int __init vmci_guest_init(void)
+{
+	return pci_register_driver(&vmci_guest_driver);
+}
+
+void __exit vmci_guest_exit(void)
+{
+	pci_unregister_driver(&vmci_guest_driver);
+}
diff --git a/drivers/misc/vmw_vmci/vmci_handle_array.c b/drivers/misc/vmw_vmci/vmci_handle_array.c
new file mode 100644
index 000000000..917e18a8a
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_handle_array.c
@@ -0,0 +1,154 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/slab.h>
+#include "vmci_handle_array.h"
+
+static size_t handle_arr_calc_size(u32 capacity)
+{
+	return VMCI_HANDLE_ARRAY_HEADER_SIZE +
+	    capacity * sizeof(struct vmci_handle);
+}
+
+struct vmci_handle_arr *vmci_handle_arr_create(u32 capacity, u32 max_capacity)
+{
+	struct vmci_handle_arr *array;
+
+	if (max_capacity == 0 || capacity > max_capacity)
+		return NULL;
+
+	if (capacity == 0)
+		capacity = min((u32)VMCI_HANDLE_ARRAY_DEFAULT_CAPACITY,
+			       max_capacity);
+
+	array = kmalloc(handle_arr_calc_size(capacity), GFP_ATOMIC);
+	if (!array)
+		return NULL;
+
+	array->capacity = capacity;
+	array->max_capacity = max_capacity;
+	array->size = 0;
+
+	return array;
+}
+
+void vmci_handle_arr_destroy(struct vmci_handle_arr *array)
+{
+	kfree(array);
+}
+
+int vmci_handle_arr_append_entry(struct vmci_handle_arr **array_ptr,
+				 struct vmci_handle handle)
+{
+	struct vmci_handle_arr *array = *array_ptr;
+
+	if (unlikely(array->size >= array->capacity)) {
+		/* reallocate. */
+		struct vmci_handle_arr *new_array;
+		u32 capacity_bump = min(array->max_capacity - array->capacity,
+					array->capacity);
+		size_t new_size = handle_arr_calc_size(array->capacity +
+						       capacity_bump);
+
+		if (array->size >= array->max_capacity)
+			return VMCI_ERROR_NO_MEM;
+
+		new_array = krealloc(array, new_size, GFP_ATOMIC);
+		if (!new_array)
+			return VMCI_ERROR_NO_MEM;
+
+		new_array->capacity += capacity_bump;
+		*array_ptr = array = new_array;
+	}
+
+	array->entries[array->size] = handle;
+	array->size++;
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Handle that was removed, VMCI_INVALID_HANDLE if entry not found.
+ */
+struct vmci_handle vmci_handle_arr_remove_entry(struct vmci_handle_arr *array,
+						struct vmci_handle entry_handle)
+{
+	struct vmci_handle handle = VMCI_INVALID_HANDLE;
+	u32 i;
+
+	for (i = 0; i < array->size; i++) {
+		if (vmci_handle_is_equal(array->entries[i], entry_handle)) {
+			handle = array->entries[i];
+			array->size--;
+			array->entries[i] = array->entries[array->size];
+			array->entries[array->size] = VMCI_INVALID_HANDLE;
+			break;
+		}
+	}
+
+	return handle;
+}
+
+/*
+ * Handle that was removed, VMCI_INVALID_HANDLE if array was empty.
+ */
+struct vmci_handle vmci_handle_arr_remove_tail(struct vmci_handle_arr *array)
+{
+	struct vmci_handle handle = VMCI_INVALID_HANDLE;
+
+	if (array->size) {
+		array->size--;
+		handle = array->entries[array->size];
+		array->entries[array->size] = VMCI_INVALID_HANDLE;
+	}
+
+	return handle;
+}
+
+/*
+ * Handle at given index, VMCI_INVALID_HANDLE if invalid index.
+ */
+struct vmci_handle
+vmci_handle_arr_get_entry(const struct vmci_handle_arr *array, u32 index)
+{
+	if (unlikely(index >= array->size))
+		return VMCI_INVALID_HANDLE;
+
+	return array->entries[index];
+}
+
+bool vmci_handle_arr_has_entry(const struct vmci_handle_arr *array,
+			       struct vmci_handle entry_handle)
+{
+	u32 i;
+
+	for (i = 0; i < array->size; i++)
+		if (vmci_handle_is_equal(array->entries[i], entry_handle))
+			return true;
+
+	return false;
+}
+
+/*
+ * NULL if the array is empty. Otherwise, a pointer to the array
+ * of VMCI handles in the handle array.
+ */
+struct vmci_handle *vmci_handle_arr_get_handles(struct vmci_handle_arr *array)
+{
+	if (array->size)
+		return array->entries;
+
+	return NULL;
+}
diff --git a/drivers/misc/vmw_vmci/vmci_handle_array.h b/drivers/misc/vmw_vmci/vmci_handle_array.h
new file mode 100644
index 000000000..0fc585978
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_handle_array.h
@@ -0,0 +1,61 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#ifndef _VMCI_HANDLE_ARRAY_H_
+#define _VMCI_HANDLE_ARRAY_H_
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/limits.h>
+#include <linux/types.h>
+
+struct vmci_handle_arr {
+	u32 capacity;
+	u32 max_capacity;
+	u32 size;
+	u32 pad;
+	struct vmci_handle entries[];
+};
+
+#define VMCI_HANDLE_ARRAY_HEADER_SIZE				\
+	offsetof(struct vmci_handle_arr, entries)
+/* Select a default capacity that results in a 64 byte sized array */
+#define VMCI_HANDLE_ARRAY_DEFAULT_CAPACITY			6
+/* Make sure that the max array size can be expressed by a u32 */
+#define VMCI_HANDLE_ARRAY_MAX_CAPACITY				\
+	((U32_MAX - VMCI_HANDLE_ARRAY_HEADER_SIZE - 1) /	\
+	sizeof(struct vmci_handle))
+
+struct vmci_handle_arr *vmci_handle_arr_create(u32 capacity, u32 max_capacity);
+void vmci_handle_arr_destroy(struct vmci_handle_arr *array);
+int vmci_handle_arr_append_entry(struct vmci_handle_arr **array_ptr,
+				 struct vmci_handle handle);
+struct vmci_handle vmci_handle_arr_remove_entry(struct vmci_handle_arr *array,
+						struct vmci_handle
+						entry_handle);
+struct vmci_handle vmci_handle_arr_remove_tail(struct vmci_handle_arr *array);
+struct vmci_handle
+vmci_handle_arr_get_entry(const struct vmci_handle_arr *array, u32 index);
+bool vmci_handle_arr_has_entry(const struct vmci_handle_arr *array,
+			       struct vmci_handle entry_handle);
+struct vmci_handle *vmci_handle_arr_get_handles(struct vmci_handle_arr *array);
+
+static inline u32 vmci_handle_arr_get_size(
+	const struct vmci_handle_arr *array)
+{
+	return array->size;
+}
+
+
+#endif /* _VMCI_HANDLE_ARRAY_H_ */
diff --git a/drivers/misc/vmw_vmci/vmci_host.c b/drivers/misc/vmw_vmci/vmci_host.c
new file mode 100644
index 000000000..83e0c95d2
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_host.c
@@ -0,0 +1,1036 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+#include <linux/moduleparam.h>
+#include <linux/miscdevice.h>
+#include <linux/interrupt.h>
+#include <linux/highmem.h>
+#include <linux/atomic.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/pci.h>
+#include <linux/smp.h>
+#include <linux/fs.h>
+#include <linux/io.h>
+
+#include "vmci_handle_array.h"
+#include "vmci_queue_pair.h"
+#include "vmci_datagram.h"
+#include "vmci_doorbell.h"
+#include "vmci_resource.h"
+#include "vmci_context.h"
+#include "vmci_driver.h"
+#include "vmci_event.h"
+
+#define VMCI_UTIL_NUM_RESOURCES 1
+
+enum {
+	VMCI_NOTIFY_RESOURCE_QUEUE_PAIR = 0,
+	VMCI_NOTIFY_RESOURCE_DOOR_BELL = 1,
+};
+
+enum {
+	VMCI_NOTIFY_RESOURCE_ACTION_NOTIFY = 0,
+	VMCI_NOTIFY_RESOURCE_ACTION_CREATE = 1,
+	VMCI_NOTIFY_RESOURCE_ACTION_DESTROY = 2,
+};
+
+/*
+ * VMCI driver initialization. This block can also be used to
+ * pass initial group membership etc.
+ */
+struct vmci_init_blk {
+	u32 cid;
+	u32 flags;
+};
+
+/* VMCIqueue_pairAllocInfo_VMToVM */
+struct vmci_qp_alloc_info_vmvm {
+	struct vmci_handle handle;
+	u32 peer;
+	u32 flags;
+	u64 produce_size;
+	u64 consume_size;
+	u64 produce_page_file;	  /* User VA. */
+	u64 consume_page_file;	  /* User VA. */
+	u64 produce_page_file_size;  /* Size of the file name array. */
+	u64 consume_page_file_size;  /* Size of the file name array. */
+	s32 result;
+	u32 _pad;
+};
+
+/* VMCISetNotifyInfo: Used to pass notify flag's address to the host driver. */
+struct vmci_set_notify_info {
+	u64 notify_uva;
+	s32 result;
+	u32 _pad;
+};
+
+/*
+ * Per-instance host state
+ */
+struct vmci_host_dev {
+	struct vmci_ctx *context;
+	int user_version;
+	enum vmci_obj_type ct_type;
+	struct mutex lock;  /* Mutex lock for vmci context access */
+};
+
+static struct vmci_ctx *host_context;
+static bool vmci_host_device_initialized;
+static atomic_t vmci_host_active_users = ATOMIC_INIT(0);
+
+/*
+ * Determines whether the VMCI host personality is
+ * available. Since the core functionality of the host driver is
+ * always present, all guests could possibly use the host
+ * personality. However, to minimize the deviation from the
+ * pre-unified driver state of affairs, we only consider the host
+ * device active if there is no active guest device or if there
+ * are VMX'en with active VMCI contexts using the host device.
+ */
+bool vmci_host_code_active(void)
+{
+	return vmci_host_device_initialized &&
+	    (!vmci_guest_code_active() ||
+	     atomic_read(&vmci_host_active_users) > 0);
+}
+
+/*
+ * Called on open of /dev/vmci.
+ */
+static int vmci_host_open(struct inode *inode, struct file *filp)
+{
+	struct vmci_host_dev *vmci_host_dev;
+
+	vmci_host_dev = kzalloc(sizeof(struct vmci_host_dev), GFP_KERNEL);
+	if (vmci_host_dev == NULL)
+		return -ENOMEM;
+
+	vmci_host_dev->ct_type = VMCIOBJ_NOT_SET;
+	mutex_init(&vmci_host_dev->lock);
+	filp->private_data = vmci_host_dev;
+
+	return 0;
+}
+
+/*
+ * Called on close of /dev/vmci, most often when the process
+ * exits.
+ */
+static int vmci_host_close(struct inode *inode, struct file *filp)
+{
+	struct vmci_host_dev *vmci_host_dev = filp->private_data;
+
+	if (vmci_host_dev->ct_type == VMCIOBJ_CONTEXT) {
+		vmci_ctx_destroy(vmci_host_dev->context);
+		vmci_host_dev->context = NULL;
+
+		/*
+		 * The number of active contexts is used to track whether any
+		 * VMX'en are using the host personality. It is incremented when
+		 * a context is created through the IOCTL_VMCI_INIT_CONTEXT
+		 * ioctl.
+		 */
+		atomic_dec(&vmci_host_active_users);
+	}
+	vmci_host_dev->ct_type = VMCIOBJ_NOT_SET;
+
+	kfree(vmci_host_dev);
+	filp->private_data = NULL;
+	return 0;
+}
+
+/*
+ * This is used to wake up the VMX when a VMCI call arrives, or
+ * to wake up select() or poll() at the next clock tick.
+ */
+static __poll_t vmci_host_poll(struct file *filp, poll_table *wait)
+{
+	struct vmci_host_dev *vmci_host_dev = filp->private_data;
+	struct vmci_ctx *context = vmci_host_dev->context;
+	__poll_t mask = 0;
+
+	if (vmci_host_dev->ct_type == VMCIOBJ_CONTEXT) {
+		/* Check for VMCI calls to this VM context. */
+		if (wait)
+			poll_wait(filp, &context->host_context.wait_queue,
+				  wait);
+
+		spin_lock(&context->lock);
+		if (context->pending_datagrams > 0 ||
+		    vmci_handle_arr_get_size(
+				context->pending_doorbell_array) > 0) {
+			mask = EPOLLIN;
+		}
+		spin_unlock(&context->lock);
+	}
+	return mask;
+}
+
+/*
+ * Copies the handles of a handle array into a user buffer, and
+ * returns the new length in userBufferSize. If the copy to the
+ * user buffer fails, the functions still returns VMCI_SUCCESS,
+ * but retval != 0.
+ */
+static int drv_cp_harray_to_user(void __user *user_buf_uva,
+				 u64 *user_buf_size,
+				 struct vmci_handle_arr *handle_array,
+				 int *retval)
+{
+	u32 array_size = 0;
+	struct vmci_handle *handles;
+
+	if (handle_array)
+		array_size = vmci_handle_arr_get_size(handle_array);
+
+	if (array_size * sizeof(*handles) > *user_buf_size)
+		return VMCI_ERROR_MORE_DATA;
+
+	*user_buf_size = array_size * sizeof(*handles);
+	if (*user_buf_size)
+		*retval = copy_to_user(user_buf_uva,
+				       vmci_handle_arr_get_handles
+				       (handle_array), *user_buf_size);
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Sets up a given context for notify to work. Maps the notify
+ * boolean in user VA into kernel space.
+ */
+static int vmci_host_setup_notify(struct vmci_ctx *context,
+				  unsigned long uva)
+{
+	int retval;
+
+	if (context->notify_page) {
+		pr_devel("%s: Notify mechanism is already set up\n", __func__);
+		return VMCI_ERROR_DUPLICATE_ENTRY;
+	}
+
+	/*
+	 * We are using 'bool' internally, but let's make sure we explicit
+	 * about the size.
+	 */
+	BUILD_BUG_ON(sizeof(bool) != sizeof(u8));
+	if (!access_ok(VERIFY_WRITE, (void __user *)uva, sizeof(u8)))
+		return VMCI_ERROR_GENERIC;
+
+	/*
+	 * Lock physical page backing a given user VA.
+	 */
+	retval = get_user_pages_fast(uva, 1, 1, &context->notify_page);
+	if (retval != 1) {
+		context->notify_page = NULL;
+		return VMCI_ERROR_GENERIC;
+	}
+
+	/*
+	 * Map the locked page and set up notify pointer.
+	 */
+	context->notify = kmap(context->notify_page) + (uva & (PAGE_SIZE - 1));
+	vmci_ctx_check_signal_notify(context);
+
+	return VMCI_SUCCESS;
+}
+
+static int vmci_host_get_version(struct vmci_host_dev *vmci_host_dev,
+				 unsigned int cmd, void __user *uptr)
+{
+	if (cmd == IOCTL_VMCI_VERSION2) {
+		int __user *vptr = uptr;
+		if (get_user(vmci_host_dev->user_version, vptr))
+			return -EFAULT;
+	}
+
+	/*
+	 * The basic logic here is:
+	 *
+	 * If the user sends in a version of 0 tell it our version.
+	 * If the user didn't send in a version, tell it our version.
+	 * If the user sent in an old version, tell it -its- version.
+	 * If the user sent in an newer version, tell it our version.
+	 *
+	 * The rationale behind telling the caller its version is that
+	 * Workstation 6.5 required that VMX and VMCI kernel module were
+	 * version sync'd.  All new VMX users will be programmed to
+	 * handle the VMCI kernel module version.
+	 */
+
+	if (vmci_host_dev->user_version > 0 &&
+	    vmci_host_dev->user_version < VMCI_VERSION_HOSTQP) {
+		return vmci_host_dev->user_version;
+	}
+
+	return VMCI_VERSION;
+}
+
+#define vmci_ioctl_err(fmt, ...)	\
+	pr_devel("%s: " fmt, ioctl_name, ##__VA_ARGS__)
+
+static int vmci_host_do_init_context(struct vmci_host_dev *vmci_host_dev,
+				     const char *ioctl_name,
+				     void __user *uptr)
+{
+	struct vmci_init_blk init_block;
+	const struct cred *cred;
+	int retval;
+
+	if (copy_from_user(&init_block, uptr, sizeof(init_block))) {
+		vmci_ioctl_err("error reading init block\n");
+		return -EFAULT;
+	}
+
+	mutex_lock(&vmci_host_dev->lock);
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_NOT_SET) {
+		vmci_ioctl_err("received VMCI init on initialized handle\n");
+		retval = -EINVAL;
+		goto out;
+	}
+
+	if (init_block.flags & ~VMCI_PRIVILEGE_FLAG_RESTRICTED) {
+		vmci_ioctl_err("unsupported VMCI restriction flag\n");
+		retval = -EINVAL;
+		goto out;
+	}
+
+	cred = get_current_cred();
+	vmci_host_dev->context = vmci_ctx_create(init_block.cid,
+						 init_block.flags, 0,
+						 vmci_host_dev->user_version,
+						 cred);
+	put_cred(cred);
+	if (IS_ERR(vmci_host_dev->context)) {
+		retval = PTR_ERR(vmci_host_dev->context);
+		vmci_ioctl_err("error initializing context\n");
+		goto out;
+	}
+
+	/*
+	 * Copy cid to userlevel, we do this to allow the VMX
+	 * to enforce its policy on cid generation.
+	 */
+	init_block.cid = vmci_ctx_get_id(vmci_host_dev->context);
+	if (copy_to_user(uptr, &init_block, sizeof(init_block))) {
+		vmci_ctx_destroy(vmci_host_dev->context);
+		vmci_host_dev->context = NULL;
+		vmci_ioctl_err("error writing init block\n");
+		retval = -EFAULT;
+		goto out;
+	}
+
+	vmci_host_dev->ct_type = VMCIOBJ_CONTEXT;
+	atomic_inc(&vmci_host_active_users);
+
+	retval = 0;
+
+out:
+	mutex_unlock(&vmci_host_dev->lock);
+	return retval;
+}
+
+static int vmci_host_do_send_datagram(struct vmci_host_dev *vmci_host_dev,
+				      const char *ioctl_name,
+				      void __user *uptr)
+{
+	struct vmci_datagram_snd_rcv_info send_info;
+	struct vmci_datagram *dg = NULL;
+	u32 cid;
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&send_info, uptr, sizeof(send_info)))
+		return -EFAULT;
+
+	if (send_info.len > VMCI_MAX_DG_SIZE) {
+		vmci_ioctl_err("datagram is too big (size=%d)\n",
+			       send_info.len);
+		return -EINVAL;
+	}
+
+	if (send_info.len < sizeof(*dg)) {
+		vmci_ioctl_err("datagram is too small (size=%d)\n",
+			       send_info.len);
+		return -EINVAL;
+	}
+
+	dg = memdup_user((void __user *)(uintptr_t)send_info.addr,
+			 send_info.len);
+	if (IS_ERR(dg)) {
+		vmci_ioctl_err(
+			"cannot allocate memory to dispatch datagram\n");
+		return PTR_ERR(dg);
+	}
+
+	if (VMCI_DG_SIZE(dg) != send_info.len) {
+		vmci_ioctl_err("datagram size mismatch\n");
+		kfree(dg);
+		return -EINVAL;
+	}
+
+	pr_devel("Datagram dst (handle=0x%x:0x%x) src (handle=0x%x:0x%x), payload (size=%llu bytes)\n",
+		 dg->dst.context, dg->dst.resource,
+		 dg->src.context, dg->src.resource,
+		 (unsigned long long)dg->payload_size);
+
+	/* Get source context id. */
+	cid = vmci_ctx_get_id(vmci_host_dev->context);
+	send_info.result = vmci_datagram_dispatch(cid, dg, true);
+	kfree(dg);
+
+	return copy_to_user(uptr, &send_info, sizeof(send_info)) ? -EFAULT : 0;
+}
+
+static int vmci_host_do_receive_datagram(struct vmci_host_dev *vmci_host_dev,
+					 const char *ioctl_name,
+					 void __user *uptr)
+{
+	struct vmci_datagram_snd_rcv_info recv_info;
+	struct vmci_datagram *dg = NULL;
+	int retval;
+	size_t size;
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&recv_info, uptr, sizeof(recv_info)))
+		return -EFAULT;
+
+	size = recv_info.len;
+	recv_info.result = vmci_ctx_dequeue_datagram(vmci_host_dev->context,
+						     &size, &dg);
+
+	if (recv_info.result >= VMCI_SUCCESS) {
+		void __user *ubuf = (void __user *)(uintptr_t)recv_info.addr;
+		retval = copy_to_user(ubuf, dg, VMCI_DG_SIZE(dg));
+		kfree(dg);
+		if (retval != 0)
+			return -EFAULT;
+	}
+
+	return copy_to_user(uptr, &recv_info, sizeof(recv_info)) ? -EFAULT : 0;
+}
+
+static int vmci_host_do_alloc_queuepair(struct vmci_host_dev *vmci_host_dev,
+					const char *ioctl_name,
+					void __user *uptr)
+{
+	struct vmci_handle handle;
+	int vmci_status;
+	int __user *retptr;
+	u32 cid;
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	cid = vmci_ctx_get_id(vmci_host_dev->context);
+
+	if (vmci_host_dev->user_version < VMCI_VERSION_NOVMVM) {
+		struct vmci_qp_alloc_info_vmvm alloc_info;
+		struct vmci_qp_alloc_info_vmvm __user *info = uptr;
+
+		if (copy_from_user(&alloc_info, uptr, sizeof(alloc_info)))
+			return -EFAULT;
+
+		handle = alloc_info.handle;
+		retptr = &info->result;
+
+		vmci_status = vmci_qp_broker_alloc(alloc_info.handle,
+						alloc_info.peer,
+						alloc_info.flags,
+						VMCI_NO_PRIVILEGE_FLAGS,
+						alloc_info.produce_size,
+						alloc_info.consume_size,
+						NULL,
+						vmci_host_dev->context);
+
+		if (vmci_status == VMCI_SUCCESS)
+			vmci_status = VMCI_SUCCESS_QUEUEPAIR_CREATE;
+	} else {
+		struct vmci_qp_alloc_info alloc_info;
+		struct vmci_qp_alloc_info __user *info = uptr;
+		struct vmci_qp_page_store page_store;
+
+		if (copy_from_user(&alloc_info, uptr, sizeof(alloc_info)))
+			return -EFAULT;
+
+		handle = alloc_info.handle;
+		retptr = &info->result;
+
+		page_store.pages = alloc_info.ppn_va;
+		page_store.len = alloc_info.num_ppns;
+
+		vmci_status = vmci_qp_broker_alloc(alloc_info.handle,
+						alloc_info.peer,
+						alloc_info.flags,
+						VMCI_NO_PRIVILEGE_FLAGS,
+						alloc_info.produce_size,
+						alloc_info.consume_size,
+						&page_store,
+						vmci_host_dev->context);
+	}
+
+	if (put_user(vmci_status, retptr)) {
+		if (vmci_status >= VMCI_SUCCESS) {
+			vmci_status = vmci_qp_broker_detach(handle,
+							vmci_host_dev->context);
+		}
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
+static int vmci_host_do_queuepair_setva(struct vmci_host_dev *vmci_host_dev,
+					const char *ioctl_name,
+					void __user *uptr)
+{
+	struct vmci_qp_set_va_info set_va_info;
+	struct vmci_qp_set_va_info __user *info = uptr;
+	s32 result;
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (vmci_host_dev->user_version < VMCI_VERSION_NOVMVM) {
+		vmci_ioctl_err("is not allowed\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&set_va_info, uptr, sizeof(set_va_info)))
+		return -EFAULT;
+
+	if (set_va_info.va) {
+		/*
+		 * VMX is passing down a new VA for the queue
+		 * pair mapping.
+		 */
+		result = vmci_qp_broker_map(set_va_info.handle,
+					    vmci_host_dev->context,
+					    set_va_info.va);
+	} else {
+		/*
+		 * The queue pair is about to be unmapped by
+		 * the VMX.
+		 */
+		result = vmci_qp_broker_unmap(set_va_info.handle,
+					 vmci_host_dev->context, 0);
+	}
+
+	return put_user(result, &info->result) ? -EFAULT : 0;
+}
+
+static int vmci_host_do_queuepair_setpf(struct vmci_host_dev *vmci_host_dev,
+					const char *ioctl_name,
+					void __user *uptr)
+{
+	struct vmci_qp_page_file_info page_file_info;
+	struct vmci_qp_page_file_info __user *info = uptr;
+	s32 result;
+
+	if (vmci_host_dev->user_version < VMCI_VERSION_HOSTQP ||
+	    vmci_host_dev->user_version >= VMCI_VERSION_NOVMVM) {
+		vmci_ioctl_err("not supported on this VMX (version=%d)\n",
+			       vmci_host_dev->user_version);
+		return -EINVAL;
+	}
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&page_file_info, uptr, sizeof(*info)))
+		return -EFAULT;
+
+	/*
+	 * Communicate success pre-emptively to the caller.  Note that the
+	 * basic premise is that it is incumbent upon the caller not to look at
+	 * the info.result field until after the ioctl() returns.  And then,
+	 * only if the ioctl() result indicates no error.  We send up the
+	 * SUCCESS status before calling SetPageStore() store because failing
+	 * to copy up the result code means unwinding the SetPageStore().
+	 *
+	 * It turns out the logic to unwind a SetPageStore() opens a can of
+	 * worms.  For example, if a host had created the queue_pair and a
+	 * guest attaches and SetPageStore() is successful but writing success
+	 * fails, then ... the host has to be stopped from writing (anymore)
+	 * data into the queue_pair.  That means an additional test in the
+	 * VMCI_Enqueue() code path.  Ugh.
+	 */
+
+	if (put_user(VMCI_SUCCESS, &info->result)) {
+		/*
+		 * In this case, we can't write a result field of the
+		 * caller's info block.  So, we don't even try to
+		 * SetPageStore().
+		 */
+		return -EFAULT;
+	}
+
+	result = vmci_qp_broker_set_page_store(page_file_info.handle,
+						page_file_info.produce_va,
+						page_file_info.consume_va,
+						vmci_host_dev->context);
+	if (result < VMCI_SUCCESS) {
+		if (put_user(result, &info->result)) {
+			/*
+			 * Note that in this case the SetPageStore()
+			 * call failed but we were unable to
+			 * communicate that to the caller (because the
+			 * copy_to_user() call failed).  So, if we
+			 * simply return an error (in this case
+			 * -EFAULT) then the caller will know that the
+			 *  SetPageStore failed even though we couldn't
+			 *  put the result code in the result field and
+			 *  indicate exactly why it failed.
+			 *
+			 * That says nothing about the issue where we
+			 * were once able to write to the caller's info
+			 * memory and now can't.  Something more
+			 * serious is probably going on than the fact
+			 * that SetPageStore() didn't work.
+			 */
+			return -EFAULT;
+		}
+	}
+
+	return 0;
+}
+
+static int vmci_host_do_qp_detach(struct vmci_host_dev *vmci_host_dev,
+				  const char *ioctl_name,
+				  void __user *uptr)
+{
+	struct vmci_qp_dtch_info detach_info;
+	struct vmci_qp_dtch_info __user *info = uptr;
+	s32 result;
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&detach_info, uptr, sizeof(detach_info)))
+		return -EFAULT;
+
+	result = vmci_qp_broker_detach(detach_info.handle,
+				       vmci_host_dev->context);
+	if (result == VMCI_SUCCESS &&
+	    vmci_host_dev->user_version < VMCI_VERSION_NOVMVM) {
+		result = VMCI_SUCCESS_LAST_DETACH;
+	}
+
+	return put_user(result, &info->result) ? -EFAULT : 0;
+}
+
+static int vmci_host_do_ctx_add_notify(struct vmci_host_dev *vmci_host_dev,
+				       const char *ioctl_name,
+				       void __user *uptr)
+{
+	struct vmci_ctx_info ar_info;
+	struct vmci_ctx_info __user *info = uptr;
+	s32 result;
+	u32 cid;
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&ar_info, uptr, sizeof(ar_info)))
+		return -EFAULT;
+
+	cid = vmci_ctx_get_id(vmci_host_dev->context);
+	result = vmci_ctx_add_notification(cid, ar_info.remote_cid);
+
+	return put_user(result, &info->result) ? -EFAULT : 0;
+}
+
+static int vmci_host_do_ctx_remove_notify(struct vmci_host_dev *vmci_host_dev,
+					  const char *ioctl_name,
+					  void __user *uptr)
+{
+	struct vmci_ctx_info ar_info;
+	struct vmci_ctx_info __user *info = uptr;
+	u32 cid;
+	int result;
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&ar_info, uptr, sizeof(ar_info)))
+		return -EFAULT;
+
+	cid = vmci_ctx_get_id(vmci_host_dev->context);
+	result = vmci_ctx_remove_notification(cid,
+					      ar_info.remote_cid);
+
+	return put_user(result, &info->result) ? -EFAULT : 0;
+}
+
+static int vmci_host_do_ctx_get_cpt_state(struct vmci_host_dev *vmci_host_dev,
+					  const char *ioctl_name,
+					  void __user *uptr)
+{
+	struct vmci_ctx_chkpt_buf_info get_info;
+	u32 cid;
+	void *cpt_buf;
+	int retval;
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&get_info, uptr, sizeof(get_info)))
+		return -EFAULT;
+
+	cid = vmci_ctx_get_id(vmci_host_dev->context);
+	get_info.result = vmci_ctx_get_chkpt_state(cid, get_info.cpt_type,
+						&get_info.buf_size, &cpt_buf);
+	if (get_info.result == VMCI_SUCCESS && get_info.buf_size) {
+		void __user *ubuf = (void __user *)(uintptr_t)get_info.cpt_buf;
+		retval = copy_to_user(ubuf, cpt_buf, get_info.buf_size);
+		kfree(cpt_buf);
+
+		if (retval)
+			return -EFAULT;
+	}
+
+	return copy_to_user(uptr, &get_info, sizeof(get_info)) ? -EFAULT : 0;
+}
+
+static int vmci_host_do_ctx_set_cpt_state(struct vmci_host_dev *vmci_host_dev,
+					  const char *ioctl_name,
+					  void __user *uptr)
+{
+	struct vmci_ctx_chkpt_buf_info set_info;
+	u32 cid;
+	void *cpt_buf;
+	int retval;
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&set_info, uptr, sizeof(set_info)))
+		return -EFAULT;
+
+	cpt_buf = kmalloc(set_info.buf_size, GFP_KERNEL);
+	if (!cpt_buf) {
+		vmci_ioctl_err(
+			"cannot allocate memory to set cpt state (type=%d)\n",
+			set_info.cpt_type);
+		return -ENOMEM;
+	}
+
+	if (copy_from_user(cpt_buf, (void __user *)(uintptr_t)set_info.cpt_buf,
+			   set_info.buf_size)) {
+		retval = -EFAULT;
+		goto out;
+	}
+
+	cid = vmci_ctx_get_id(vmci_host_dev->context);
+	set_info.result = vmci_ctx_set_chkpt_state(cid, set_info.cpt_type,
+						   set_info.buf_size, cpt_buf);
+
+	retval = copy_to_user(uptr, &set_info, sizeof(set_info)) ? -EFAULT : 0;
+
+out:
+	kfree(cpt_buf);
+	return retval;
+}
+
+static int vmci_host_do_get_context_id(struct vmci_host_dev *vmci_host_dev,
+				       const char *ioctl_name,
+				       void __user *uptr)
+{
+	u32 __user *u32ptr = uptr;
+
+	return put_user(VMCI_HOST_CONTEXT_ID, u32ptr) ? -EFAULT : 0;
+}
+
+static int vmci_host_do_set_notify(struct vmci_host_dev *vmci_host_dev,
+				   const char *ioctl_name,
+				   void __user *uptr)
+{
+	struct vmci_set_notify_info notify_info;
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&notify_info, uptr, sizeof(notify_info)))
+		return -EFAULT;
+
+	if (notify_info.notify_uva) {
+		notify_info.result =
+			vmci_host_setup_notify(vmci_host_dev->context,
+					       notify_info.notify_uva);
+	} else {
+		vmci_ctx_unset_notify(vmci_host_dev->context);
+		notify_info.result = VMCI_SUCCESS;
+	}
+
+	return copy_to_user(uptr, &notify_info, sizeof(notify_info)) ?
+		-EFAULT : 0;
+}
+
+static int vmci_host_do_notify_resource(struct vmci_host_dev *vmci_host_dev,
+					const char *ioctl_name,
+					void __user *uptr)
+{
+	struct vmci_dbell_notify_resource_info info;
+	u32 cid;
+
+	if (vmci_host_dev->user_version < VMCI_VERSION_NOTIFY) {
+		vmci_ioctl_err("invalid for current VMX versions\n");
+		return -EINVAL;
+	}
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&info, uptr, sizeof(info)))
+		return -EFAULT;
+
+	cid = vmci_ctx_get_id(vmci_host_dev->context);
+
+	switch (info.action) {
+	case VMCI_NOTIFY_RESOURCE_ACTION_NOTIFY:
+		if (info.resource == VMCI_NOTIFY_RESOURCE_DOOR_BELL) {
+			u32 flags = VMCI_NO_PRIVILEGE_FLAGS;
+			info.result = vmci_ctx_notify_dbell(cid, info.handle,
+							    flags);
+		} else {
+			info.result = VMCI_ERROR_UNAVAILABLE;
+		}
+		break;
+
+	case VMCI_NOTIFY_RESOURCE_ACTION_CREATE:
+		info.result = vmci_ctx_dbell_create(cid, info.handle);
+		break;
+
+	case VMCI_NOTIFY_RESOURCE_ACTION_DESTROY:
+		info.result = vmci_ctx_dbell_destroy(cid, info.handle);
+		break;
+
+	default:
+		vmci_ioctl_err("got unknown action (action=%d)\n",
+			       info.action);
+		info.result = VMCI_ERROR_INVALID_ARGS;
+	}
+
+	return copy_to_user(uptr, &info, sizeof(info)) ? -EFAULT : 0;
+}
+
+static int vmci_host_do_recv_notifications(struct vmci_host_dev *vmci_host_dev,
+					   const char *ioctl_name,
+					   void __user *uptr)
+{
+	struct vmci_ctx_notify_recv_info info;
+	struct vmci_handle_arr *db_handle_array;
+	struct vmci_handle_arr *qp_handle_array;
+	void __user *ubuf;
+	u32 cid;
+	int retval = 0;
+
+	if (vmci_host_dev->ct_type != VMCIOBJ_CONTEXT) {
+		vmci_ioctl_err("only valid for contexts\n");
+		return -EINVAL;
+	}
+
+	if (vmci_host_dev->user_version < VMCI_VERSION_NOTIFY) {
+		vmci_ioctl_err("not supported for the current vmx version\n");
+		return -EINVAL;
+	}
+
+	if (copy_from_user(&info, uptr, sizeof(info)))
+		return -EFAULT;
+
+	if ((info.db_handle_buf_size && !info.db_handle_buf_uva) ||
+	    (info.qp_handle_buf_size && !info.qp_handle_buf_uva)) {
+		return -EINVAL;
+	}
+
+	cid = vmci_ctx_get_id(vmci_host_dev->context);
+
+	info.result = vmci_ctx_rcv_notifications_get(cid,
+				&db_handle_array, &qp_handle_array);
+	if (info.result != VMCI_SUCCESS)
+		return copy_to_user(uptr, &info, sizeof(info)) ? -EFAULT : 0;
+
+	ubuf = (void __user *)(uintptr_t)info.db_handle_buf_uva;
+	info.result = drv_cp_harray_to_user(ubuf, &info.db_handle_buf_size,
+					    db_handle_array, &retval);
+	if (info.result == VMCI_SUCCESS && !retval) {
+		ubuf = (void __user *)(uintptr_t)info.qp_handle_buf_uva;
+		info.result = drv_cp_harray_to_user(ubuf,
+						    &info.qp_handle_buf_size,
+						    qp_handle_array, &retval);
+	}
+
+	if (!retval && copy_to_user(uptr, &info, sizeof(info)))
+		retval = -EFAULT;
+
+	vmci_ctx_rcv_notifications_release(cid,
+				db_handle_array, qp_handle_array,
+				info.result == VMCI_SUCCESS && !retval);
+
+	return retval;
+}
+
+static long vmci_host_unlocked_ioctl(struct file *filp,
+				     unsigned int iocmd, unsigned long ioarg)
+{
+#define VMCI_DO_IOCTL(ioctl_name, ioctl_fn) do {			\
+		char *name = __stringify(IOCTL_VMCI_ ## ioctl_name);	\
+		return vmci_host_do_ ## ioctl_fn(			\
+			vmci_host_dev, name, uptr);			\
+	} while (0)
+
+	struct vmci_host_dev *vmci_host_dev = filp->private_data;
+	void __user *uptr = (void __user *)ioarg;
+
+	switch (iocmd) {
+	case IOCTL_VMCI_INIT_CONTEXT:
+		VMCI_DO_IOCTL(INIT_CONTEXT, init_context);
+	case IOCTL_VMCI_DATAGRAM_SEND:
+		VMCI_DO_IOCTL(DATAGRAM_SEND, send_datagram);
+	case IOCTL_VMCI_DATAGRAM_RECEIVE:
+		VMCI_DO_IOCTL(DATAGRAM_RECEIVE, receive_datagram);
+	case IOCTL_VMCI_QUEUEPAIR_ALLOC:
+		VMCI_DO_IOCTL(QUEUEPAIR_ALLOC, alloc_queuepair);
+	case IOCTL_VMCI_QUEUEPAIR_SETVA:
+		VMCI_DO_IOCTL(QUEUEPAIR_SETVA, queuepair_setva);
+	case IOCTL_VMCI_QUEUEPAIR_SETPAGEFILE:
+		VMCI_DO_IOCTL(QUEUEPAIR_SETPAGEFILE, queuepair_setpf);
+	case IOCTL_VMCI_QUEUEPAIR_DETACH:
+		VMCI_DO_IOCTL(QUEUEPAIR_DETACH, qp_detach);
+	case IOCTL_VMCI_CTX_ADD_NOTIFICATION:
+		VMCI_DO_IOCTL(CTX_ADD_NOTIFICATION, ctx_add_notify);
+	case IOCTL_VMCI_CTX_REMOVE_NOTIFICATION:
+		VMCI_DO_IOCTL(CTX_REMOVE_NOTIFICATION, ctx_remove_notify);
+	case IOCTL_VMCI_CTX_GET_CPT_STATE:
+		VMCI_DO_IOCTL(CTX_GET_CPT_STATE, ctx_get_cpt_state);
+	case IOCTL_VMCI_CTX_SET_CPT_STATE:
+		VMCI_DO_IOCTL(CTX_SET_CPT_STATE, ctx_set_cpt_state);
+	case IOCTL_VMCI_GET_CONTEXT_ID:
+		VMCI_DO_IOCTL(GET_CONTEXT_ID, get_context_id);
+	case IOCTL_VMCI_SET_NOTIFY:
+		VMCI_DO_IOCTL(SET_NOTIFY, set_notify);
+	case IOCTL_VMCI_NOTIFY_RESOURCE:
+		VMCI_DO_IOCTL(NOTIFY_RESOURCE, notify_resource);
+	case IOCTL_VMCI_NOTIFICATIONS_RECEIVE:
+		VMCI_DO_IOCTL(NOTIFICATIONS_RECEIVE, recv_notifications);
+
+	case IOCTL_VMCI_VERSION:
+	case IOCTL_VMCI_VERSION2:
+		return vmci_host_get_version(vmci_host_dev, iocmd, uptr);
+
+	default:
+		pr_devel("%s: Unknown ioctl (iocmd=%d)\n", __func__, iocmd);
+		return -EINVAL;
+	}
+
+#undef VMCI_DO_IOCTL
+}
+
+static const struct file_operations vmuser_fops = {
+	.owner		= THIS_MODULE,
+	.open		= vmci_host_open,
+	.release	= vmci_host_close,
+	.poll		= vmci_host_poll,
+	.unlocked_ioctl	= vmci_host_unlocked_ioctl,
+	.compat_ioctl	= vmci_host_unlocked_ioctl,
+};
+
+static struct miscdevice vmci_host_miscdev = {
+	 .name = "vmci",
+	 .minor = MISC_DYNAMIC_MINOR,
+	 .fops = &vmuser_fops,
+};
+
+int __init vmci_host_init(void)
+{
+	int error;
+
+	host_context = vmci_ctx_create(VMCI_HOST_CONTEXT_ID,
+					VMCI_DEFAULT_PROC_PRIVILEGE_FLAGS,
+					-1, VMCI_VERSION, NULL);
+	if (IS_ERR(host_context)) {
+		error = PTR_ERR(host_context);
+		pr_warn("Failed to initialize VMCIContext (error%d)\n",
+			error);
+		return error;
+	}
+
+	error = misc_register(&vmci_host_miscdev);
+	if (error) {
+		pr_warn("Module registration error (name=%s, major=%d, minor=%d, err=%d)\n",
+			vmci_host_miscdev.name,
+			MISC_MAJOR, vmci_host_miscdev.minor,
+			error);
+		pr_warn("Unable to initialize host personality\n");
+		vmci_ctx_destroy(host_context);
+		return error;
+	}
+
+	pr_info("VMCI host device registered (name=%s, major=%d, minor=%d)\n",
+		vmci_host_miscdev.name, MISC_MAJOR, vmci_host_miscdev.minor);
+
+	vmci_host_device_initialized = true;
+	return 0;
+}
+
+void __exit vmci_host_exit(void)
+{
+	vmci_host_device_initialized = false;
+
+	misc_deregister(&vmci_host_miscdev);
+	vmci_ctx_destroy(host_context);
+	vmci_qp_broker_exit();
+
+	pr_debug("VMCI host driver module unloaded\n");
+}
diff --git a/drivers/misc/vmw_vmci/vmci_queue_pair.c b/drivers/misc/vmw_vmci/vmci_queue_pair.c
new file mode 100644
index 000000000..db433d285
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_queue_pair.c
@@ -0,0 +1,3272 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+#include <linux/highmem.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/pagemap.h>
+#include <linux/pci.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/uio.h>
+#include <linux/wait.h>
+#include <linux/vmalloc.h>
+#include <linux/skbuff.h>
+
+#include "vmci_handle_array.h"
+#include "vmci_queue_pair.h"
+#include "vmci_datagram.h"
+#include "vmci_resource.h"
+#include "vmci_context.h"
+#include "vmci_driver.h"
+#include "vmci_event.h"
+#include "vmci_route.h"
+
+/*
+ * In the following, we will distinguish between two kinds of VMX processes -
+ * the ones with versions lower than VMCI_VERSION_NOVMVM that use specialized
+ * VMCI page files in the VMX and supporting VM to VM communication and the
+ * newer ones that use the guest memory directly. We will in the following
+ * refer to the older VMX versions as old-style VMX'en, and the newer ones as
+ * new-style VMX'en.
+ *
+ * The state transition datagram is as follows (the VMCIQPB_ prefix has been
+ * removed for readability) - see below for more details on the transtions:
+ *
+ *            --------------  NEW  -------------
+ *            |                                |
+ *           \_/                              \_/
+ *     CREATED_NO_MEM <-----------------> CREATED_MEM
+ *            |    |                           |
+ *            |    o-----------------------o   |
+ *            |                            |   |
+ *           \_/                          \_/ \_/
+ *     ATTACHED_NO_MEM <----------------> ATTACHED_MEM
+ *            |                            |   |
+ *            |     o----------------------o   |
+ *            |     |                          |
+ *           \_/   \_/                        \_/
+ *     SHUTDOWN_NO_MEM <----------------> SHUTDOWN_MEM
+ *            |                                |
+ *            |                                |
+ *            -------------> gone <-------------
+ *
+ * In more detail. When a VMCI queue pair is first created, it will be in the
+ * VMCIQPB_NEW state. It will then move into one of the following states:
+ *
+ * - VMCIQPB_CREATED_NO_MEM: this state indicates that either:
+ *
+ *     - the created was performed by a host endpoint, in which case there is
+ *       no backing memory yet.
+ *
+ *     - the create was initiated by an old-style VMX, that uses
+ *       vmci_qp_broker_set_page_store to specify the UVAs of the queue pair at
+ *       a later point in time. This state can be distinguished from the one
+ *       above by the context ID of the creator. A host side is not allowed to
+ *       attach until the page store has been set.
+ *
+ * - VMCIQPB_CREATED_MEM: this state is the result when the queue pair
+ *     is created by a VMX using the queue pair device backend that
+ *     sets the UVAs of the queue pair immediately and stores the
+ *     information for later attachers. At this point, it is ready for
+ *     the host side to attach to it.
+ *
+ * Once the queue pair is in one of the created states (with the exception of
+ * the case mentioned for older VMX'en above), it is possible to attach to the
+ * queue pair. Again we have two new states possible:
+ *
+ * - VMCIQPB_ATTACHED_MEM: this state can be reached through the following
+ *   paths:
+ *
+ *     - from VMCIQPB_CREATED_NO_MEM when a new-style VMX allocates a queue
+ *       pair, and attaches to a queue pair previously created by the host side.
+ *
+ *     - from VMCIQPB_CREATED_MEM when the host side attaches to a queue pair
+ *       already created by a guest.
+ *
+ *     - from VMCIQPB_ATTACHED_NO_MEM, when an old-style VMX calls
+ *       vmci_qp_broker_set_page_store (see below).
+ *
+ * - VMCIQPB_ATTACHED_NO_MEM: If the queue pair already was in the
+ *     VMCIQPB_CREATED_NO_MEM due to a host side create, an old-style VMX will
+ *     bring the queue pair into this state. Once vmci_qp_broker_set_page_store
+ *     is called to register the user memory, the VMCIQPB_ATTACH_MEM state
+ *     will be entered.
+ *
+ * From the attached queue pair, the queue pair can enter the shutdown states
+ * when either side of the queue pair detaches. If the guest side detaches
+ * first, the queue pair will enter the VMCIQPB_SHUTDOWN_NO_MEM state, where
+ * the content of the queue pair will no longer be available. If the host
+ * side detaches first, the queue pair will either enter the
+ * VMCIQPB_SHUTDOWN_MEM, if the guest memory is currently mapped, or
+ * VMCIQPB_SHUTDOWN_NO_MEM, if the guest memory is not mapped
+ * (e.g., the host detaches while a guest is stunned).
+ *
+ * New-style VMX'en will also unmap guest memory, if the guest is
+ * quiesced, e.g., during a snapshot operation. In that case, the guest
+ * memory will no longer be available, and the queue pair will transition from
+ * *_MEM state to a *_NO_MEM state. The VMX may later map the memory once more,
+ * in which case the queue pair will transition from the *_NO_MEM state at that
+ * point back to the *_MEM state. Note that the *_NO_MEM state may have changed,
+ * since the peer may have either attached or detached in the meantime. The
+ * values are laid out such that ++ on a state will move from a *_NO_MEM to a
+ * *_MEM state, and vice versa.
+ */
+
+/* The Kernel specific component of the struct vmci_queue structure. */
+struct vmci_queue_kern_if {
+	struct mutex __mutex;	/* Protects the queue. */
+	struct mutex *mutex;	/* Shared by producer and consumer queues. */
+	size_t num_pages;	/* Number of pages incl. header. */
+	bool host;		/* Host or guest? */
+	union {
+		struct {
+			dma_addr_t *pas;
+			void **vas;
+		} g;		/* Used by the guest. */
+		struct {
+			struct page **page;
+			struct page **header_page;
+		} h;		/* Used by the host. */
+	} u;
+};
+
+/*
+ * This structure is opaque to the clients.
+ */
+struct vmci_qp {
+	struct vmci_handle handle;
+	struct vmci_queue *produce_q;
+	struct vmci_queue *consume_q;
+	u64 produce_q_size;
+	u64 consume_q_size;
+	u32 peer;
+	u32 flags;
+	u32 priv_flags;
+	bool guest_endpoint;
+	unsigned int blocked;
+	unsigned int generation;
+	wait_queue_head_t event;
+};
+
+enum qp_broker_state {
+	VMCIQPB_NEW,
+	VMCIQPB_CREATED_NO_MEM,
+	VMCIQPB_CREATED_MEM,
+	VMCIQPB_ATTACHED_NO_MEM,
+	VMCIQPB_ATTACHED_MEM,
+	VMCIQPB_SHUTDOWN_NO_MEM,
+	VMCIQPB_SHUTDOWN_MEM,
+	VMCIQPB_GONE
+};
+
+#define QPBROKERSTATE_HAS_MEM(_qpb) (_qpb->state == VMCIQPB_CREATED_MEM || \
+				     _qpb->state == VMCIQPB_ATTACHED_MEM || \
+				     _qpb->state == VMCIQPB_SHUTDOWN_MEM)
+
+/*
+ * In the queue pair broker, we always use the guest point of view for
+ * the produce and consume queue values and references, e.g., the
+ * produce queue size stored is the guests produce queue size. The
+ * host endpoint will need to swap these around. The only exception is
+ * the local queue pairs on the host, in which case the host endpoint
+ * that creates the queue pair will have the right orientation, and
+ * the attaching host endpoint will need to swap.
+ */
+struct qp_entry {
+	struct list_head list_item;
+	struct vmci_handle handle;
+	u32 peer;
+	u32 flags;
+	u64 produce_size;
+	u64 consume_size;
+	u32 ref_count;
+};
+
+struct qp_broker_entry {
+	struct vmci_resource resource;
+	struct qp_entry qp;
+	u32 create_id;
+	u32 attach_id;
+	enum qp_broker_state state;
+	bool require_trusted_attach;
+	bool created_by_trusted;
+	bool vmci_page_files;	/* Created by VMX using VMCI page files */
+	struct vmci_queue *produce_q;
+	struct vmci_queue *consume_q;
+	struct vmci_queue_header saved_produce_q;
+	struct vmci_queue_header saved_consume_q;
+	vmci_event_release_cb wakeup_cb;
+	void *client_data;
+	void *local_mem;	/* Kernel memory for local queue pair */
+};
+
+struct qp_guest_endpoint {
+	struct vmci_resource resource;
+	struct qp_entry qp;
+	u64 num_ppns;
+	void *produce_q;
+	void *consume_q;
+	struct ppn_set ppn_set;
+};
+
+struct qp_list {
+	struct list_head head;
+	struct mutex mutex;	/* Protect queue list. */
+};
+
+static struct qp_list qp_broker_list = {
+	.head = LIST_HEAD_INIT(qp_broker_list.head),
+	.mutex = __MUTEX_INITIALIZER(qp_broker_list.mutex),
+};
+
+static struct qp_list qp_guest_endpoints = {
+	.head = LIST_HEAD_INIT(qp_guest_endpoints.head),
+	.mutex = __MUTEX_INITIALIZER(qp_guest_endpoints.mutex),
+};
+
+#define INVALID_VMCI_GUEST_MEM_ID  0
+#define QPE_NUM_PAGES(_QPE) ((u32) \
+			     (DIV_ROUND_UP(_QPE.produce_size, PAGE_SIZE) + \
+			      DIV_ROUND_UP(_QPE.consume_size, PAGE_SIZE) + 2))
+
+
+/*
+ * Frees kernel VA space for a given queue and its queue header, and
+ * frees physical data pages.
+ */
+static void qp_free_queue(void *q, u64 size)
+{
+	struct vmci_queue *queue = q;
+
+	if (queue) {
+		u64 i;
+
+		/* Given size does not include header, so add in a page here. */
+		for (i = 0; i < DIV_ROUND_UP(size, PAGE_SIZE) + 1; i++) {
+			dma_free_coherent(&vmci_pdev->dev, PAGE_SIZE,
+					  queue->kernel_if->u.g.vas[i],
+					  queue->kernel_if->u.g.pas[i]);
+		}
+
+		vfree(queue);
+	}
+}
+
+/*
+ * Allocates kernel queue pages of specified size with IOMMU mappings,
+ * plus space for the queue structure/kernel interface and the queue
+ * header.
+ */
+static void *qp_alloc_queue(u64 size, u32 flags)
+{
+	u64 i;
+	struct vmci_queue *queue;
+	size_t pas_size;
+	size_t vas_size;
+	size_t queue_size = sizeof(*queue) + sizeof(*queue->kernel_if);
+	u64 num_pages;
+
+	if (size > SIZE_MAX - PAGE_SIZE)
+		return NULL;
+	num_pages = DIV_ROUND_UP(size, PAGE_SIZE) + 1;
+	if (num_pages >
+		 (SIZE_MAX - queue_size) /
+		 (sizeof(*queue->kernel_if->u.g.pas) +
+		  sizeof(*queue->kernel_if->u.g.vas)))
+		return NULL;
+
+	pas_size = num_pages * sizeof(*queue->kernel_if->u.g.pas);
+	vas_size = num_pages * sizeof(*queue->kernel_if->u.g.vas);
+	queue_size += pas_size + vas_size;
+
+	queue = vmalloc(queue_size);
+	if (!queue)
+		return NULL;
+
+	queue->q_header = NULL;
+	queue->saved_header = NULL;
+	queue->kernel_if = (struct vmci_queue_kern_if *)(queue + 1);
+	queue->kernel_if->mutex = NULL;
+	queue->kernel_if->num_pages = num_pages;
+	queue->kernel_if->u.g.pas = (dma_addr_t *)(queue->kernel_if + 1);
+	queue->kernel_if->u.g.vas =
+		(void **)((u8 *)queue->kernel_if->u.g.pas + pas_size);
+	queue->kernel_if->host = false;
+
+	for (i = 0; i < num_pages; i++) {
+		queue->kernel_if->u.g.vas[i] =
+			dma_alloc_coherent(&vmci_pdev->dev, PAGE_SIZE,
+					   &queue->kernel_if->u.g.pas[i],
+					   GFP_KERNEL);
+		if (!queue->kernel_if->u.g.vas[i]) {
+			/* Size excl. the header. */
+			qp_free_queue(queue, i * PAGE_SIZE);
+			return NULL;
+		}
+	}
+
+	/* Queue header is the first page. */
+	queue->q_header = queue->kernel_if->u.g.vas[0];
+
+	return queue;
+}
+
+/*
+ * Copies from a given buffer or iovector to a VMCI Queue.  Uses
+ * kmap()/kunmap() to dynamically map/unmap required portions of the queue
+ * by traversing the offset -> page translation structure for the queue.
+ * Assumes that offset + size does not wrap around in the queue.
+ */
+static int qp_memcpy_to_queue_iter(struct vmci_queue *queue,
+				  u64 queue_offset,
+				  struct iov_iter *from,
+				  size_t size)
+{
+	struct vmci_queue_kern_if *kernel_if = queue->kernel_if;
+	size_t bytes_copied = 0;
+
+	while (bytes_copied < size) {
+		const u64 page_index =
+			(queue_offset + bytes_copied) / PAGE_SIZE;
+		const size_t page_offset =
+		    (queue_offset + bytes_copied) & (PAGE_SIZE - 1);
+		void *va;
+		size_t to_copy;
+
+		if (kernel_if->host)
+			va = kmap(kernel_if->u.h.page[page_index]);
+		else
+			va = kernel_if->u.g.vas[page_index + 1];
+			/* Skip header. */
+
+		if (size - bytes_copied > PAGE_SIZE - page_offset)
+			/* Enough payload to fill up from this page. */
+			to_copy = PAGE_SIZE - page_offset;
+		else
+			to_copy = size - bytes_copied;
+
+		if (!copy_from_iter_full((u8 *)va + page_offset, to_copy,
+					 from)) {
+			if (kernel_if->host)
+				kunmap(kernel_if->u.h.page[page_index]);
+			return VMCI_ERROR_INVALID_ARGS;
+		}
+		bytes_copied += to_copy;
+		if (kernel_if->host)
+			kunmap(kernel_if->u.h.page[page_index]);
+	}
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Copies to a given buffer or iovector from a VMCI Queue.  Uses
+ * kmap()/kunmap() to dynamically map/unmap required portions of the queue
+ * by traversing the offset -> page translation structure for the queue.
+ * Assumes that offset + size does not wrap around in the queue.
+ */
+static int qp_memcpy_from_queue_iter(struct iov_iter *to,
+				    const struct vmci_queue *queue,
+				    u64 queue_offset, size_t size)
+{
+	struct vmci_queue_kern_if *kernel_if = queue->kernel_if;
+	size_t bytes_copied = 0;
+
+	while (bytes_copied < size) {
+		const u64 page_index =
+			(queue_offset + bytes_copied) / PAGE_SIZE;
+		const size_t page_offset =
+		    (queue_offset + bytes_copied) & (PAGE_SIZE - 1);
+		void *va;
+		size_t to_copy;
+		int err;
+
+		if (kernel_if->host)
+			va = kmap(kernel_if->u.h.page[page_index]);
+		else
+			va = kernel_if->u.g.vas[page_index + 1];
+			/* Skip header. */
+
+		if (size - bytes_copied > PAGE_SIZE - page_offset)
+			/* Enough payload to fill up this page. */
+			to_copy = PAGE_SIZE - page_offset;
+		else
+			to_copy = size - bytes_copied;
+
+		err = copy_to_iter((u8 *)va + page_offset, to_copy, to);
+		if (err != to_copy) {
+			if (kernel_if->host)
+				kunmap(kernel_if->u.h.page[page_index]);
+			return VMCI_ERROR_INVALID_ARGS;
+		}
+		bytes_copied += to_copy;
+		if (kernel_if->host)
+			kunmap(kernel_if->u.h.page[page_index]);
+	}
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Allocates two list of PPNs --- one for the pages in the produce queue,
+ * and the other for the pages in the consume queue. Intializes the list
+ * of PPNs with the page frame numbers of the KVA for the two queues (and
+ * the queue headers).
+ */
+static int qp_alloc_ppn_set(void *prod_q,
+			    u64 num_produce_pages,
+			    void *cons_q,
+			    u64 num_consume_pages, struct ppn_set *ppn_set)
+{
+	u32 *produce_ppns;
+	u32 *consume_ppns;
+	struct vmci_queue *produce_q = prod_q;
+	struct vmci_queue *consume_q = cons_q;
+	u64 i;
+
+	if (!produce_q || !num_produce_pages || !consume_q ||
+	    !num_consume_pages || !ppn_set)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	if (ppn_set->initialized)
+		return VMCI_ERROR_ALREADY_EXISTS;
+
+	produce_ppns =
+	    kmalloc_array(num_produce_pages, sizeof(*produce_ppns),
+			  GFP_KERNEL);
+	if (!produce_ppns)
+		return VMCI_ERROR_NO_MEM;
+
+	consume_ppns =
+	    kmalloc_array(num_consume_pages, sizeof(*consume_ppns),
+			  GFP_KERNEL);
+	if (!consume_ppns) {
+		kfree(produce_ppns);
+		return VMCI_ERROR_NO_MEM;
+	}
+
+	for (i = 0; i < num_produce_pages; i++) {
+		unsigned long pfn;
+
+		produce_ppns[i] =
+			produce_q->kernel_if->u.g.pas[i] >> PAGE_SHIFT;
+		pfn = produce_ppns[i];
+
+		/* Fail allocation if PFN isn't supported by hypervisor. */
+		if (sizeof(pfn) > sizeof(*produce_ppns)
+		    && pfn != produce_ppns[i])
+			goto ppn_error;
+	}
+
+	for (i = 0; i < num_consume_pages; i++) {
+		unsigned long pfn;
+
+		consume_ppns[i] =
+			consume_q->kernel_if->u.g.pas[i] >> PAGE_SHIFT;
+		pfn = consume_ppns[i];
+
+		/* Fail allocation if PFN isn't supported by hypervisor. */
+		if (sizeof(pfn) > sizeof(*consume_ppns)
+		    && pfn != consume_ppns[i])
+			goto ppn_error;
+	}
+
+	ppn_set->num_produce_pages = num_produce_pages;
+	ppn_set->num_consume_pages = num_consume_pages;
+	ppn_set->produce_ppns = produce_ppns;
+	ppn_set->consume_ppns = consume_ppns;
+	ppn_set->initialized = true;
+	return VMCI_SUCCESS;
+
+ ppn_error:
+	kfree(produce_ppns);
+	kfree(consume_ppns);
+	return VMCI_ERROR_INVALID_ARGS;
+}
+
+/*
+ * Frees the two list of PPNs for a queue pair.
+ */
+static void qp_free_ppn_set(struct ppn_set *ppn_set)
+{
+	if (ppn_set->initialized) {
+		/* Do not call these functions on NULL inputs. */
+		kfree(ppn_set->produce_ppns);
+		kfree(ppn_set->consume_ppns);
+	}
+	memset(ppn_set, 0, sizeof(*ppn_set));
+}
+
+/*
+ * Populates the list of PPNs in the hypercall structure with the PPNS
+ * of the produce queue and the consume queue.
+ */
+static int qp_populate_ppn_set(u8 *call_buf, const struct ppn_set *ppn_set)
+{
+	memcpy(call_buf, ppn_set->produce_ppns,
+	       ppn_set->num_produce_pages * sizeof(*ppn_set->produce_ppns));
+	memcpy(call_buf +
+	       ppn_set->num_produce_pages * sizeof(*ppn_set->produce_ppns),
+	       ppn_set->consume_ppns,
+	       ppn_set->num_consume_pages * sizeof(*ppn_set->consume_ppns));
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Allocates kernel VA space of specified size plus space for the queue
+ * and kernel interface.  This is different from the guest queue allocator,
+ * because we do not allocate our own queue header/data pages here but
+ * share those of the guest.
+ */
+static struct vmci_queue *qp_host_alloc_queue(u64 size)
+{
+	struct vmci_queue *queue;
+	size_t queue_page_size;
+	u64 num_pages;
+	const size_t queue_size = sizeof(*queue) + sizeof(*(queue->kernel_if));
+
+	if (size > SIZE_MAX - PAGE_SIZE)
+		return NULL;
+	num_pages = DIV_ROUND_UP(size, PAGE_SIZE) + 1;
+	if (num_pages > (SIZE_MAX - queue_size) /
+		 sizeof(*queue->kernel_if->u.h.page))
+		return NULL;
+
+	queue_page_size = num_pages * sizeof(*queue->kernel_if->u.h.page);
+
+	if (queue_size + queue_page_size > KMALLOC_MAX_SIZE)
+		return NULL;
+
+	queue = kzalloc(queue_size + queue_page_size, GFP_KERNEL);
+	if (queue) {
+		queue->q_header = NULL;
+		queue->saved_header = NULL;
+		queue->kernel_if = (struct vmci_queue_kern_if *)(queue + 1);
+		queue->kernel_if->host = true;
+		queue->kernel_if->mutex = NULL;
+		queue->kernel_if->num_pages = num_pages;
+		queue->kernel_if->u.h.header_page =
+		    (struct page **)((u8 *)queue + queue_size);
+		queue->kernel_if->u.h.page =
+			&queue->kernel_if->u.h.header_page[1];
+	}
+
+	return queue;
+}
+
+/*
+ * Frees kernel memory for a given queue (header plus translation
+ * structure).
+ */
+static void qp_host_free_queue(struct vmci_queue *queue, u64 queue_size)
+{
+	kfree(queue);
+}
+
+/*
+ * Initialize the mutex for the pair of queues.  This mutex is used to
+ * protect the q_header and the buffer from changing out from under any
+ * users of either queue.  Of course, it's only any good if the mutexes
+ * are actually acquired.  Queue structure must lie on non-paged memory
+ * or we cannot guarantee access to the mutex.
+ */
+static void qp_init_queue_mutex(struct vmci_queue *produce_q,
+				struct vmci_queue *consume_q)
+{
+	/*
+	 * Only the host queue has shared state - the guest queues do not
+	 * need to synchronize access using a queue mutex.
+	 */
+
+	if (produce_q->kernel_if->host) {
+		produce_q->kernel_if->mutex = &produce_q->kernel_if->__mutex;
+		consume_q->kernel_if->mutex = &produce_q->kernel_if->__mutex;
+		mutex_init(produce_q->kernel_if->mutex);
+	}
+}
+
+/*
+ * Cleans up the mutex for the pair of queues.
+ */
+static void qp_cleanup_queue_mutex(struct vmci_queue *produce_q,
+				   struct vmci_queue *consume_q)
+{
+	if (produce_q->kernel_if->host) {
+		produce_q->kernel_if->mutex = NULL;
+		consume_q->kernel_if->mutex = NULL;
+	}
+}
+
+/*
+ * Acquire the mutex for the queue.  Note that the produce_q and
+ * the consume_q share a mutex.  So, only one of the two need to
+ * be passed in to this routine.  Either will work just fine.
+ */
+static void qp_acquire_queue_mutex(struct vmci_queue *queue)
+{
+	if (queue->kernel_if->host)
+		mutex_lock(queue->kernel_if->mutex);
+}
+
+/*
+ * Release the mutex for the queue.  Note that the produce_q and
+ * the consume_q share a mutex.  So, only one of the two need to
+ * be passed in to this routine.  Either will work just fine.
+ */
+static void qp_release_queue_mutex(struct vmci_queue *queue)
+{
+	if (queue->kernel_if->host)
+		mutex_unlock(queue->kernel_if->mutex);
+}
+
+/*
+ * Helper function to release pages in the PageStoreAttachInfo
+ * previously obtained using get_user_pages.
+ */
+static void qp_release_pages(struct page **pages,
+			     u64 num_pages, bool dirty)
+{
+	int i;
+
+	for (i = 0; i < num_pages; i++) {
+		if (dirty)
+			set_page_dirty_lock(pages[i]);
+
+		put_page(pages[i]);
+		pages[i] = NULL;
+	}
+}
+
+/*
+ * Lock the user pages referenced by the {produce,consume}Buffer
+ * struct into memory and populate the {produce,consume}Pages
+ * arrays in the attach structure with them.
+ */
+static int qp_host_get_user_memory(u64 produce_uva,
+				   u64 consume_uva,
+				   struct vmci_queue *produce_q,
+				   struct vmci_queue *consume_q)
+{
+	int retval;
+	int err = VMCI_SUCCESS;
+
+	retval = get_user_pages_fast((uintptr_t) produce_uva,
+				     produce_q->kernel_if->num_pages, 1,
+				     produce_q->kernel_if->u.h.header_page);
+	if (retval < (int)produce_q->kernel_if->num_pages) {
+		pr_debug("get_user_pages_fast(produce) failed (retval=%d)",
+			retval);
+		if (retval > 0)
+			qp_release_pages(produce_q->kernel_if->u.h.header_page,
+					retval, false);
+		err = VMCI_ERROR_NO_MEM;
+		goto out;
+	}
+
+	retval = get_user_pages_fast((uintptr_t) consume_uva,
+				     consume_q->kernel_if->num_pages, 1,
+				     consume_q->kernel_if->u.h.header_page);
+	if (retval < (int)consume_q->kernel_if->num_pages) {
+		pr_debug("get_user_pages_fast(consume) failed (retval=%d)",
+			retval);
+		if (retval > 0)
+			qp_release_pages(consume_q->kernel_if->u.h.header_page,
+					retval, false);
+		qp_release_pages(produce_q->kernel_if->u.h.header_page,
+				 produce_q->kernel_if->num_pages, false);
+		err = VMCI_ERROR_NO_MEM;
+	}
+
+ out:
+	return err;
+}
+
+/*
+ * Registers the specification of the user pages used for backing a queue
+ * pair. Enough information to map in pages is stored in the OS specific
+ * part of the struct vmci_queue structure.
+ */
+static int qp_host_register_user_memory(struct vmci_qp_page_store *page_store,
+					struct vmci_queue *produce_q,
+					struct vmci_queue *consume_q)
+{
+	u64 produce_uva;
+	u64 consume_uva;
+
+	/*
+	 * The new style and the old style mapping only differs in
+	 * that we either get a single or two UVAs, so we split the
+	 * single UVA range at the appropriate spot.
+	 */
+	produce_uva = page_store->pages;
+	consume_uva = page_store->pages +
+	    produce_q->kernel_if->num_pages * PAGE_SIZE;
+	return qp_host_get_user_memory(produce_uva, consume_uva, produce_q,
+				       consume_q);
+}
+
+/*
+ * Releases and removes the references to user pages stored in the attach
+ * struct.  Pages are released from the page cache and may become
+ * swappable again.
+ */
+static void qp_host_unregister_user_memory(struct vmci_queue *produce_q,
+					   struct vmci_queue *consume_q)
+{
+	qp_release_pages(produce_q->kernel_if->u.h.header_page,
+			 produce_q->kernel_if->num_pages, true);
+	memset(produce_q->kernel_if->u.h.header_page, 0,
+	       sizeof(*produce_q->kernel_if->u.h.header_page) *
+	       produce_q->kernel_if->num_pages);
+	qp_release_pages(consume_q->kernel_if->u.h.header_page,
+			 consume_q->kernel_if->num_pages, true);
+	memset(consume_q->kernel_if->u.h.header_page, 0,
+	       sizeof(*consume_q->kernel_if->u.h.header_page) *
+	       consume_q->kernel_if->num_pages);
+}
+
+/*
+ * Once qp_host_register_user_memory has been performed on a
+ * queue, the queue pair headers can be mapped into the
+ * kernel. Once mapped, they must be unmapped with
+ * qp_host_unmap_queues prior to calling
+ * qp_host_unregister_user_memory.
+ * Pages are pinned.
+ */
+static int qp_host_map_queues(struct vmci_queue *produce_q,
+			      struct vmci_queue *consume_q)
+{
+	int result;
+
+	if (!produce_q->q_header || !consume_q->q_header) {
+		struct page *headers[2];
+
+		if (produce_q->q_header != consume_q->q_header)
+			return VMCI_ERROR_QUEUEPAIR_MISMATCH;
+
+		if (produce_q->kernel_if->u.h.header_page == NULL ||
+		    *produce_q->kernel_if->u.h.header_page == NULL)
+			return VMCI_ERROR_UNAVAILABLE;
+
+		headers[0] = *produce_q->kernel_if->u.h.header_page;
+		headers[1] = *consume_q->kernel_if->u.h.header_page;
+
+		produce_q->q_header = vmap(headers, 2, VM_MAP, PAGE_KERNEL);
+		if (produce_q->q_header != NULL) {
+			consume_q->q_header =
+			    (struct vmci_queue_header *)((u8 *)
+							 produce_q->q_header +
+							 PAGE_SIZE);
+			result = VMCI_SUCCESS;
+		} else {
+			pr_warn("vmap failed\n");
+			result = VMCI_ERROR_NO_MEM;
+		}
+	} else {
+		result = VMCI_SUCCESS;
+	}
+
+	return result;
+}
+
+/*
+ * Unmaps previously mapped queue pair headers from the kernel.
+ * Pages are unpinned.
+ */
+static int qp_host_unmap_queues(u32 gid,
+				struct vmci_queue *produce_q,
+				struct vmci_queue *consume_q)
+{
+	if (produce_q->q_header) {
+		if (produce_q->q_header < consume_q->q_header)
+			vunmap(produce_q->q_header);
+		else
+			vunmap(consume_q->q_header);
+
+		produce_q->q_header = NULL;
+		consume_q->q_header = NULL;
+	}
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Finds the entry in the list corresponding to a given handle. Assumes
+ * that the list is locked.
+ */
+static struct qp_entry *qp_list_find(struct qp_list *qp_list,
+				     struct vmci_handle handle)
+{
+	struct qp_entry *entry;
+
+	if (vmci_handle_is_invalid(handle))
+		return NULL;
+
+	list_for_each_entry(entry, &qp_list->head, list_item) {
+		if (vmci_handle_is_equal(entry->handle, handle))
+			return entry;
+	}
+
+	return NULL;
+}
+
+/*
+ * Finds the entry in the list corresponding to a given handle.
+ */
+static struct qp_guest_endpoint *
+qp_guest_handle_to_entry(struct vmci_handle handle)
+{
+	struct qp_guest_endpoint *entry;
+	struct qp_entry *qp = qp_list_find(&qp_guest_endpoints, handle);
+
+	entry = qp ? container_of(
+		qp, struct qp_guest_endpoint, qp) : NULL;
+	return entry;
+}
+
+/*
+ * Finds the entry in the list corresponding to a given handle.
+ */
+static struct qp_broker_entry *
+qp_broker_handle_to_entry(struct vmci_handle handle)
+{
+	struct qp_broker_entry *entry;
+	struct qp_entry *qp = qp_list_find(&qp_broker_list, handle);
+
+	entry = qp ? container_of(
+		qp, struct qp_broker_entry, qp) : NULL;
+	return entry;
+}
+
+/*
+ * Dispatches a queue pair event message directly into the local event
+ * queue.
+ */
+static int qp_notify_peer_local(bool attach, struct vmci_handle handle)
+{
+	u32 context_id = vmci_get_context_id();
+	struct vmci_event_qp ev;
+
+	ev.msg.hdr.dst = vmci_make_handle(context_id, VMCI_EVENT_HANDLER);
+	ev.msg.hdr.src = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+					  VMCI_CONTEXT_RESOURCE_ID);
+	ev.msg.hdr.payload_size = sizeof(ev) - sizeof(ev.msg.hdr);
+	ev.msg.event_data.event =
+	    attach ? VMCI_EVENT_QP_PEER_ATTACH : VMCI_EVENT_QP_PEER_DETACH;
+	ev.payload.peer_id = context_id;
+	ev.payload.handle = handle;
+
+	return vmci_event_dispatch(&ev.msg.hdr);
+}
+
+/*
+ * Allocates and initializes a qp_guest_endpoint structure.
+ * Allocates a queue_pair rid (and handle) iff the given entry has
+ * an invalid handle.  0 through VMCI_RESERVED_RESOURCE_ID_MAX
+ * are reserved handles.  Assumes that the QP list mutex is held
+ * by the caller.
+ */
+static struct qp_guest_endpoint *
+qp_guest_endpoint_create(struct vmci_handle handle,
+			 u32 peer,
+			 u32 flags,
+			 u64 produce_size,
+			 u64 consume_size,
+			 void *produce_q,
+			 void *consume_q)
+{
+	int result;
+	struct qp_guest_endpoint *entry;
+	/* One page each for the queue headers. */
+	const u64 num_ppns = DIV_ROUND_UP(produce_size, PAGE_SIZE) +
+	    DIV_ROUND_UP(consume_size, PAGE_SIZE) + 2;
+
+	if (vmci_handle_is_invalid(handle)) {
+		u32 context_id = vmci_get_context_id();
+
+		handle = vmci_make_handle(context_id, VMCI_INVALID_ID);
+	}
+
+	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+	if (entry) {
+		entry->qp.peer = peer;
+		entry->qp.flags = flags;
+		entry->qp.produce_size = produce_size;
+		entry->qp.consume_size = consume_size;
+		entry->qp.ref_count = 0;
+		entry->num_ppns = num_ppns;
+		entry->produce_q = produce_q;
+		entry->consume_q = consume_q;
+		INIT_LIST_HEAD(&entry->qp.list_item);
+
+		/* Add resource obj */
+		result = vmci_resource_add(&entry->resource,
+					   VMCI_RESOURCE_TYPE_QPAIR_GUEST,
+					   handle);
+		entry->qp.handle = vmci_resource_handle(&entry->resource);
+		if ((result != VMCI_SUCCESS) ||
+		    qp_list_find(&qp_guest_endpoints, entry->qp.handle)) {
+			pr_warn("Failed to add new resource (handle=0x%x:0x%x), error: %d",
+				handle.context, handle.resource, result);
+			kfree(entry);
+			entry = NULL;
+		}
+	}
+	return entry;
+}
+
+/*
+ * Frees a qp_guest_endpoint structure.
+ */
+static void qp_guest_endpoint_destroy(struct qp_guest_endpoint *entry)
+{
+	qp_free_ppn_set(&entry->ppn_set);
+	qp_cleanup_queue_mutex(entry->produce_q, entry->consume_q);
+	qp_free_queue(entry->produce_q, entry->qp.produce_size);
+	qp_free_queue(entry->consume_q, entry->qp.consume_size);
+	/* Unlink from resource hash table and free callback */
+	vmci_resource_remove(&entry->resource);
+
+	kfree(entry);
+}
+
+/*
+ * Helper to make a queue_pairAlloc hypercall when the driver is
+ * supporting a guest device.
+ */
+static int qp_alloc_hypercall(const struct qp_guest_endpoint *entry)
+{
+	struct vmci_qp_alloc_msg *alloc_msg;
+	size_t msg_size;
+	int result;
+
+	if (!entry || entry->num_ppns <= 2)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	msg_size = sizeof(*alloc_msg) +
+	    (size_t) entry->num_ppns * sizeof(u32);
+	alloc_msg = kmalloc(msg_size, GFP_KERNEL);
+	if (!alloc_msg)
+		return VMCI_ERROR_NO_MEM;
+
+	alloc_msg->hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+					      VMCI_QUEUEPAIR_ALLOC);
+	alloc_msg->hdr.src = VMCI_ANON_SRC_HANDLE;
+	alloc_msg->hdr.payload_size = msg_size - VMCI_DG_HEADERSIZE;
+	alloc_msg->handle = entry->qp.handle;
+	alloc_msg->peer = entry->qp.peer;
+	alloc_msg->flags = entry->qp.flags;
+	alloc_msg->produce_size = entry->qp.produce_size;
+	alloc_msg->consume_size = entry->qp.consume_size;
+	alloc_msg->num_ppns = entry->num_ppns;
+
+	result = qp_populate_ppn_set((u8 *)alloc_msg + sizeof(*alloc_msg),
+				     &entry->ppn_set);
+	if (result == VMCI_SUCCESS)
+		result = vmci_send_datagram(&alloc_msg->hdr);
+
+	kfree(alloc_msg);
+
+	return result;
+}
+
+/*
+ * Helper to make a queue_pairDetach hypercall when the driver is
+ * supporting a guest device.
+ */
+static int qp_detatch_hypercall(struct vmci_handle handle)
+{
+	struct vmci_qp_detach_msg detach_msg;
+
+	detach_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+					      VMCI_QUEUEPAIR_DETACH);
+	detach_msg.hdr.src = VMCI_ANON_SRC_HANDLE;
+	detach_msg.hdr.payload_size = sizeof(handle);
+	detach_msg.handle = handle;
+
+	return vmci_send_datagram(&detach_msg.hdr);
+}
+
+/*
+ * Adds the given entry to the list. Assumes that the list is locked.
+ */
+static void qp_list_add_entry(struct qp_list *qp_list, struct qp_entry *entry)
+{
+	if (entry)
+		list_add(&entry->list_item, &qp_list->head);
+}
+
+/*
+ * Removes the given entry from the list. Assumes that the list is locked.
+ */
+static void qp_list_remove_entry(struct qp_list *qp_list,
+				 struct qp_entry *entry)
+{
+	if (entry)
+		list_del(&entry->list_item);
+}
+
+/*
+ * Helper for VMCI queue_pair detach interface. Frees the physical
+ * pages for the queue pair.
+ */
+static int qp_detatch_guest_work(struct vmci_handle handle)
+{
+	int result;
+	struct qp_guest_endpoint *entry;
+	u32 ref_count = ~0;	/* To avoid compiler warning below */
+
+	mutex_lock(&qp_guest_endpoints.mutex);
+
+	entry = qp_guest_handle_to_entry(handle);
+	if (!entry) {
+		mutex_unlock(&qp_guest_endpoints.mutex);
+		return VMCI_ERROR_NOT_FOUND;
+	}
+
+	if (entry->qp.flags & VMCI_QPFLAG_LOCAL) {
+		result = VMCI_SUCCESS;
+
+		if (entry->qp.ref_count > 1) {
+			result = qp_notify_peer_local(false, handle);
+			/*
+			 * We can fail to notify a local queuepair
+			 * because we can't allocate.  We still want
+			 * to release the entry if that happens, so
+			 * don't bail out yet.
+			 */
+		}
+	} else {
+		result = qp_detatch_hypercall(handle);
+		if (result < VMCI_SUCCESS) {
+			/*
+			 * We failed to notify a non-local queuepair.
+			 * That other queuepair might still be
+			 * accessing the shared memory, so don't
+			 * release the entry yet.  It will get cleaned
+			 * up by VMCIqueue_pair_Exit() if necessary
+			 * (assuming we are going away, otherwise why
+			 * did this fail?).
+			 */
+
+			mutex_unlock(&qp_guest_endpoints.mutex);
+			return result;
+		}
+	}
+
+	/*
+	 * If we get here then we either failed to notify a local queuepair, or
+	 * we succeeded in all cases.  Release the entry if required.
+	 */
+
+	entry->qp.ref_count--;
+	if (entry->qp.ref_count == 0)
+		qp_list_remove_entry(&qp_guest_endpoints, &entry->qp);
+
+	/* If we didn't remove the entry, this could change once we unlock. */
+	if (entry)
+		ref_count = entry->qp.ref_count;
+
+	mutex_unlock(&qp_guest_endpoints.mutex);
+
+	if (ref_count == 0)
+		qp_guest_endpoint_destroy(entry);
+
+	return result;
+}
+
+/*
+ * This functions handles the actual allocation of a VMCI queue
+ * pair guest endpoint. Allocates physical pages for the queue
+ * pair. It makes OS dependent calls through generic wrappers.
+ */
+static int qp_alloc_guest_work(struct vmci_handle *handle,
+			       struct vmci_queue **produce_q,
+			       u64 produce_size,
+			       struct vmci_queue **consume_q,
+			       u64 consume_size,
+			       u32 peer,
+			       u32 flags,
+			       u32 priv_flags)
+{
+	const u64 num_produce_pages =
+	    DIV_ROUND_UP(produce_size, PAGE_SIZE) + 1;
+	const u64 num_consume_pages =
+	    DIV_ROUND_UP(consume_size, PAGE_SIZE) + 1;
+	void *my_produce_q = NULL;
+	void *my_consume_q = NULL;
+	int result;
+	struct qp_guest_endpoint *queue_pair_entry = NULL;
+
+	if (priv_flags != VMCI_NO_PRIVILEGE_FLAGS)
+		return VMCI_ERROR_NO_ACCESS;
+
+	mutex_lock(&qp_guest_endpoints.mutex);
+
+	queue_pair_entry = qp_guest_handle_to_entry(*handle);
+	if (queue_pair_entry) {
+		if (queue_pair_entry->qp.flags & VMCI_QPFLAG_LOCAL) {
+			/* Local attach case. */
+			if (queue_pair_entry->qp.ref_count > 1) {
+				pr_devel("Error attempting to attach more than once\n");
+				result = VMCI_ERROR_UNAVAILABLE;
+				goto error_keep_entry;
+			}
+
+			if (queue_pair_entry->qp.produce_size != consume_size ||
+			    queue_pair_entry->qp.consume_size !=
+			    produce_size ||
+			    queue_pair_entry->qp.flags !=
+			    (flags & ~VMCI_QPFLAG_ATTACH_ONLY)) {
+				pr_devel("Error mismatched queue pair in local attach\n");
+				result = VMCI_ERROR_QUEUEPAIR_MISMATCH;
+				goto error_keep_entry;
+			}
+
+			/*
+			 * Do a local attach.  We swap the consume and
+			 * produce queues for the attacher and deliver
+			 * an attach event.
+			 */
+			result = qp_notify_peer_local(true, *handle);
+			if (result < VMCI_SUCCESS)
+				goto error_keep_entry;
+
+			my_produce_q = queue_pair_entry->consume_q;
+			my_consume_q = queue_pair_entry->produce_q;
+			goto out;
+		}
+
+		result = VMCI_ERROR_ALREADY_EXISTS;
+		goto error_keep_entry;
+	}
+
+	my_produce_q = qp_alloc_queue(produce_size, flags);
+	if (!my_produce_q) {
+		pr_warn("Error allocating pages for produce queue\n");
+		result = VMCI_ERROR_NO_MEM;
+		goto error;
+	}
+
+	my_consume_q = qp_alloc_queue(consume_size, flags);
+	if (!my_consume_q) {
+		pr_warn("Error allocating pages for consume queue\n");
+		result = VMCI_ERROR_NO_MEM;
+		goto error;
+	}
+
+	queue_pair_entry = qp_guest_endpoint_create(*handle, peer, flags,
+						    produce_size, consume_size,
+						    my_produce_q, my_consume_q);
+	if (!queue_pair_entry) {
+		pr_warn("Error allocating memory in %s\n", __func__);
+		result = VMCI_ERROR_NO_MEM;
+		goto error;
+	}
+
+	result = qp_alloc_ppn_set(my_produce_q, num_produce_pages, my_consume_q,
+				  num_consume_pages,
+				  &queue_pair_entry->ppn_set);
+	if (result < VMCI_SUCCESS) {
+		pr_warn("qp_alloc_ppn_set failed\n");
+		goto error;
+	}
+
+	/*
+	 * It's only necessary to notify the host if this queue pair will be
+	 * attached to from another context.
+	 */
+	if (queue_pair_entry->qp.flags & VMCI_QPFLAG_LOCAL) {
+		/* Local create case. */
+		u32 context_id = vmci_get_context_id();
+
+		/*
+		 * Enforce similar checks on local queue pairs as we
+		 * do for regular ones.  The handle's context must
+		 * match the creator or attacher context id (here they
+		 * are both the current context id) and the
+		 * attach-only flag cannot exist during create.  We
+		 * also ensure specified peer is this context or an
+		 * invalid one.
+		 */
+		if (queue_pair_entry->qp.handle.context != context_id ||
+		    (queue_pair_entry->qp.peer != VMCI_INVALID_ID &&
+		     queue_pair_entry->qp.peer != context_id)) {
+			result = VMCI_ERROR_NO_ACCESS;
+			goto error;
+		}
+
+		if (queue_pair_entry->qp.flags & VMCI_QPFLAG_ATTACH_ONLY) {
+			result = VMCI_ERROR_NOT_FOUND;
+			goto error;
+		}
+	} else {
+		result = qp_alloc_hypercall(queue_pair_entry);
+		if (result < VMCI_SUCCESS) {
+			pr_warn("qp_alloc_hypercall result = %d\n", result);
+			goto error;
+		}
+	}
+
+	qp_init_queue_mutex((struct vmci_queue *)my_produce_q,
+			    (struct vmci_queue *)my_consume_q);
+
+	qp_list_add_entry(&qp_guest_endpoints, &queue_pair_entry->qp);
+
+ out:
+	queue_pair_entry->qp.ref_count++;
+	*handle = queue_pair_entry->qp.handle;
+	*produce_q = (struct vmci_queue *)my_produce_q;
+	*consume_q = (struct vmci_queue *)my_consume_q;
+
+	/*
+	 * We should initialize the queue pair header pages on a local
+	 * queue pair create.  For non-local queue pairs, the
+	 * hypervisor initializes the header pages in the create step.
+	 */
+	if ((queue_pair_entry->qp.flags & VMCI_QPFLAG_LOCAL) &&
+	    queue_pair_entry->qp.ref_count == 1) {
+		vmci_q_header_init((*produce_q)->q_header, *handle);
+		vmci_q_header_init((*consume_q)->q_header, *handle);
+	}
+
+	mutex_unlock(&qp_guest_endpoints.mutex);
+
+	return VMCI_SUCCESS;
+
+ error:
+	mutex_unlock(&qp_guest_endpoints.mutex);
+	if (queue_pair_entry) {
+		/* The queues will be freed inside the destroy routine. */
+		qp_guest_endpoint_destroy(queue_pair_entry);
+	} else {
+		qp_free_queue(my_produce_q, produce_size);
+		qp_free_queue(my_consume_q, consume_size);
+	}
+	return result;
+
+ error_keep_entry:
+	/* This path should only be used when an existing entry was found. */
+	mutex_unlock(&qp_guest_endpoints.mutex);
+	return result;
+}
+
+/*
+ * The first endpoint issuing a queue pair allocation will create the state
+ * of the queue pair in the queue pair broker.
+ *
+ * If the creator is a guest, it will associate a VMX virtual address range
+ * with the queue pair as specified by the page_store. For compatibility with
+ * older VMX'en, that would use a separate step to set the VMX virtual
+ * address range, the virtual address range can be registered later using
+ * vmci_qp_broker_set_page_store. In that case, a page_store of NULL should be
+ * used.
+ *
+ * If the creator is the host, a page_store of NULL should be used as well,
+ * since the host is not able to supply a page store for the queue pair.
+ *
+ * For older VMX and host callers, the queue pair will be created in the
+ * VMCIQPB_CREATED_NO_MEM state, and for current VMX callers, it will be
+ * created in VMCOQPB_CREATED_MEM state.
+ */
+static int qp_broker_create(struct vmci_handle handle,
+			    u32 peer,
+			    u32 flags,
+			    u32 priv_flags,
+			    u64 produce_size,
+			    u64 consume_size,
+			    struct vmci_qp_page_store *page_store,
+			    struct vmci_ctx *context,
+			    vmci_event_release_cb wakeup_cb,
+			    void *client_data, struct qp_broker_entry **ent)
+{
+	struct qp_broker_entry *entry = NULL;
+	const u32 context_id = vmci_ctx_get_id(context);
+	bool is_local = flags & VMCI_QPFLAG_LOCAL;
+	int result;
+	u64 guest_produce_size;
+	u64 guest_consume_size;
+
+	/* Do not create if the caller asked not to. */
+	if (flags & VMCI_QPFLAG_ATTACH_ONLY)
+		return VMCI_ERROR_NOT_FOUND;
+
+	/*
+	 * Creator's context ID should match handle's context ID or the creator
+	 * must allow the context in handle's context ID as the "peer".
+	 */
+	if (handle.context != context_id && handle.context != peer)
+		return VMCI_ERROR_NO_ACCESS;
+
+	if (VMCI_CONTEXT_IS_VM(context_id) && VMCI_CONTEXT_IS_VM(peer))
+		return VMCI_ERROR_DST_UNREACHABLE;
+
+	/*
+	 * Creator's context ID for local queue pairs should match the
+	 * peer, if a peer is specified.
+	 */
+	if (is_local && peer != VMCI_INVALID_ID && context_id != peer)
+		return VMCI_ERROR_NO_ACCESS;
+
+	entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
+	if (!entry)
+		return VMCI_ERROR_NO_MEM;
+
+	if (vmci_ctx_get_id(context) == VMCI_HOST_CONTEXT_ID && !is_local) {
+		/*
+		 * The queue pair broker entry stores values from the guest
+		 * point of view, so a creating host side endpoint should swap
+		 * produce and consume values -- unless it is a local queue
+		 * pair, in which case no swapping is necessary, since the local
+		 * attacher will swap queues.
+		 */
+
+		guest_produce_size = consume_size;
+		guest_consume_size = produce_size;
+	} else {
+		guest_produce_size = produce_size;
+		guest_consume_size = consume_size;
+	}
+
+	entry->qp.handle = handle;
+	entry->qp.peer = peer;
+	entry->qp.flags = flags;
+	entry->qp.produce_size = guest_produce_size;
+	entry->qp.consume_size = guest_consume_size;
+	entry->qp.ref_count = 1;
+	entry->create_id = context_id;
+	entry->attach_id = VMCI_INVALID_ID;
+	entry->state = VMCIQPB_NEW;
+	entry->require_trusted_attach =
+	    !!(context->priv_flags & VMCI_PRIVILEGE_FLAG_RESTRICTED);
+	entry->created_by_trusted =
+	    !!(priv_flags & VMCI_PRIVILEGE_FLAG_TRUSTED);
+	entry->vmci_page_files = false;
+	entry->wakeup_cb = wakeup_cb;
+	entry->client_data = client_data;
+	entry->produce_q = qp_host_alloc_queue(guest_produce_size);
+	if (entry->produce_q == NULL) {
+		result = VMCI_ERROR_NO_MEM;
+		goto error;
+	}
+	entry->consume_q = qp_host_alloc_queue(guest_consume_size);
+	if (entry->consume_q == NULL) {
+		result = VMCI_ERROR_NO_MEM;
+		goto error;
+	}
+
+	qp_init_queue_mutex(entry->produce_q, entry->consume_q);
+
+	INIT_LIST_HEAD(&entry->qp.list_item);
+
+	if (is_local) {
+		u8 *tmp;
+
+		entry->local_mem = kcalloc(QPE_NUM_PAGES(entry->qp),
+					   PAGE_SIZE, GFP_KERNEL);
+		if (entry->local_mem == NULL) {
+			result = VMCI_ERROR_NO_MEM;
+			goto error;
+		}
+		entry->state = VMCIQPB_CREATED_MEM;
+		entry->produce_q->q_header = entry->local_mem;
+		tmp = (u8 *)entry->local_mem + PAGE_SIZE *
+		    (DIV_ROUND_UP(entry->qp.produce_size, PAGE_SIZE) + 1);
+		entry->consume_q->q_header = (struct vmci_queue_header *)tmp;
+	} else if (page_store) {
+		/*
+		 * The VMX already initialized the queue pair headers, so no
+		 * need for the kernel side to do that.
+		 */
+		result = qp_host_register_user_memory(page_store,
+						      entry->produce_q,
+						      entry->consume_q);
+		if (result < VMCI_SUCCESS)
+			goto error;
+
+		entry->state = VMCIQPB_CREATED_MEM;
+	} else {
+		/*
+		 * A create without a page_store may be either a host
+		 * side create (in which case we are waiting for the
+		 * guest side to supply the memory) or an old style
+		 * queue pair create (in which case we will expect a
+		 * set page store call as the next step).
+		 */
+		entry->state = VMCIQPB_CREATED_NO_MEM;
+	}
+
+	qp_list_add_entry(&qp_broker_list, &entry->qp);
+	if (ent != NULL)
+		*ent = entry;
+
+	/* Add to resource obj */
+	result = vmci_resource_add(&entry->resource,
+				   VMCI_RESOURCE_TYPE_QPAIR_HOST,
+				   handle);
+	if (result != VMCI_SUCCESS) {
+		pr_warn("Failed to add new resource (handle=0x%x:0x%x), error: %d",
+			handle.context, handle.resource, result);
+		goto error;
+	}
+
+	entry->qp.handle = vmci_resource_handle(&entry->resource);
+	if (is_local) {
+		vmci_q_header_init(entry->produce_q->q_header,
+				   entry->qp.handle);
+		vmci_q_header_init(entry->consume_q->q_header,
+				   entry->qp.handle);
+	}
+
+	vmci_ctx_qp_create(context, entry->qp.handle);
+
+	return VMCI_SUCCESS;
+
+ error:
+	if (entry != NULL) {
+		qp_host_free_queue(entry->produce_q, guest_produce_size);
+		qp_host_free_queue(entry->consume_q, guest_consume_size);
+		kfree(entry);
+	}
+
+	return result;
+}
+
+/*
+ * Enqueues an event datagram to notify the peer VM attached to
+ * the given queue pair handle about attach/detach event by the
+ * given VM.  Returns Payload size of datagram enqueued on
+ * success, error code otherwise.
+ */
+static int qp_notify_peer(bool attach,
+			  struct vmci_handle handle,
+			  u32 my_id,
+			  u32 peer_id)
+{
+	int rv;
+	struct vmci_event_qp ev;
+
+	if (vmci_handle_is_invalid(handle) || my_id == VMCI_INVALID_ID ||
+	    peer_id == VMCI_INVALID_ID)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	/*
+	 * In vmci_ctx_enqueue_datagram() we enforce the upper limit on
+	 * number of pending events from the hypervisor to a given VM
+	 * otherwise a rogue VM could do an arbitrary number of attach
+	 * and detach operations causing memory pressure in the host
+	 * kernel.
+	 */
+
+	ev.msg.hdr.dst = vmci_make_handle(peer_id, VMCI_EVENT_HANDLER);
+	ev.msg.hdr.src = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+					  VMCI_CONTEXT_RESOURCE_ID);
+	ev.msg.hdr.payload_size = sizeof(ev) - sizeof(ev.msg.hdr);
+	ev.msg.event_data.event = attach ?
+	    VMCI_EVENT_QP_PEER_ATTACH : VMCI_EVENT_QP_PEER_DETACH;
+	ev.payload.handle = handle;
+	ev.payload.peer_id = my_id;
+
+	rv = vmci_datagram_dispatch(VMCI_HYPERVISOR_CONTEXT_ID,
+				    &ev.msg.hdr, false);
+	if (rv < VMCI_SUCCESS)
+		pr_warn("Failed to enqueue queue_pair %s event datagram for context (ID=0x%x)\n",
+			attach ? "ATTACH" : "DETACH", peer_id);
+
+	return rv;
+}
+
+/*
+ * The second endpoint issuing a queue pair allocation will attach to
+ * the queue pair registered with the queue pair broker.
+ *
+ * If the attacher is a guest, it will associate a VMX virtual address
+ * range with the queue pair as specified by the page_store. At this
+ * point, the already attach host endpoint may start using the queue
+ * pair, and an attach event is sent to it. For compatibility with
+ * older VMX'en, that used a separate step to set the VMX virtual
+ * address range, the virtual address range can be registered later
+ * using vmci_qp_broker_set_page_store. In that case, a page_store of
+ * NULL should be used, and the attach event will be generated once
+ * the actual page store has been set.
+ *
+ * If the attacher is the host, a page_store of NULL should be used as
+ * well, since the page store information is already set by the guest.
+ *
+ * For new VMX and host callers, the queue pair will be moved to the
+ * VMCIQPB_ATTACHED_MEM state, and for older VMX callers, it will be
+ * moved to the VMCOQPB_ATTACHED_NO_MEM state.
+ */
+static int qp_broker_attach(struct qp_broker_entry *entry,
+			    u32 peer,
+			    u32 flags,
+			    u32 priv_flags,
+			    u64 produce_size,
+			    u64 consume_size,
+			    struct vmci_qp_page_store *page_store,
+			    struct vmci_ctx *context,
+			    vmci_event_release_cb wakeup_cb,
+			    void *client_data,
+			    struct qp_broker_entry **ent)
+{
+	const u32 context_id = vmci_ctx_get_id(context);
+	bool is_local = flags & VMCI_QPFLAG_LOCAL;
+	int result;
+
+	if (entry->state != VMCIQPB_CREATED_NO_MEM &&
+	    entry->state != VMCIQPB_CREATED_MEM)
+		return VMCI_ERROR_UNAVAILABLE;
+
+	if (is_local) {
+		if (!(entry->qp.flags & VMCI_QPFLAG_LOCAL) ||
+		    context_id != entry->create_id) {
+			return VMCI_ERROR_INVALID_ARGS;
+		}
+	} else if (context_id == entry->create_id ||
+		   context_id == entry->attach_id) {
+		return VMCI_ERROR_ALREADY_EXISTS;
+	}
+
+	if (VMCI_CONTEXT_IS_VM(context_id) &&
+	    VMCI_CONTEXT_IS_VM(entry->create_id))
+		return VMCI_ERROR_DST_UNREACHABLE;
+
+	/*
+	 * If we are attaching from a restricted context then the queuepair
+	 * must have been created by a trusted endpoint.
+	 */
+	if ((context->priv_flags & VMCI_PRIVILEGE_FLAG_RESTRICTED) &&
+	    !entry->created_by_trusted)
+		return VMCI_ERROR_NO_ACCESS;
+
+	/*
+	 * If we are attaching to a queuepair that was created by a restricted
+	 * context then we must be trusted.
+	 */
+	if (entry->require_trusted_attach &&
+	    (!(priv_flags & VMCI_PRIVILEGE_FLAG_TRUSTED)))
+		return VMCI_ERROR_NO_ACCESS;
+
+	/*
+	 * If the creator specifies VMCI_INVALID_ID in "peer" field, access
+	 * control check is not performed.
+	 */
+	if (entry->qp.peer != VMCI_INVALID_ID && entry->qp.peer != context_id)
+		return VMCI_ERROR_NO_ACCESS;
+
+	if (entry->create_id == VMCI_HOST_CONTEXT_ID) {
+		/*
+		 * Do not attach if the caller doesn't support Host Queue Pairs
+		 * and a host created this queue pair.
+		 */
+
+		if (!vmci_ctx_supports_host_qp(context))
+			return VMCI_ERROR_INVALID_RESOURCE;
+
+	} else if (context_id == VMCI_HOST_CONTEXT_ID) {
+		struct vmci_ctx *create_context;
+		bool supports_host_qp;
+
+		/*
+		 * Do not attach a host to a user created queue pair if that
+		 * user doesn't support host queue pair end points.
+		 */
+
+		create_context = vmci_ctx_get(entry->create_id);
+		supports_host_qp = vmci_ctx_supports_host_qp(create_context);
+		vmci_ctx_put(create_context);
+
+		if (!supports_host_qp)
+			return VMCI_ERROR_INVALID_RESOURCE;
+	}
+
+	if ((entry->qp.flags & ~VMCI_QP_ASYMM) != (flags & ~VMCI_QP_ASYMM_PEER))
+		return VMCI_ERROR_QUEUEPAIR_MISMATCH;
+
+	if (context_id != VMCI_HOST_CONTEXT_ID) {
+		/*
+		 * The queue pair broker entry stores values from the guest
+		 * point of view, so an attaching guest should match the values
+		 * stored in the entry.
+		 */
+
+		if (entry->qp.produce_size != produce_size ||
+		    entry->qp.consume_size != consume_size) {
+			return VMCI_ERROR_QUEUEPAIR_MISMATCH;
+		}
+	} else if (entry->qp.produce_size != consume_size ||
+		   entry->qp.consume_size != produce_size) {
+		return VMCI_ERROR_QUEUEPAIR_MISMATCH;
+	}
+
+	if (context_id != VMCI_HOST_CONTEXT_ID) {
+		/*
+		 * If a guest attached to a queue pair, it will supply
+		 * the backing memory.  If this is a pre NOVMVM vmx,
+		 * the backing memory will be supplied by calling
+		 * vmci_qp_broker_set_page_store() following the
+		 * return of the vmci_qp_broker_alloc() call. If it is
+		 * a vmx of version NOVMVM or later, the page store
+		 * must be supplied as part of the
+		 * vmci_qp_broker_alloc call.  Under all circumstances
+		 * must the initially created queue pair not have any
+		 * memory associated with it already.
+		 */
+
+		if (entry->state != VMCIQPB_CREATED_NO_MEM)
+			return VMCI_ERROR_INVALID_ARGS;
+
+		if (page_store != NULL) {
+			/*
+			 * Patch up host state to point to guest
+			 * supplied memory. The VMX already
+			 * initialized the queue pair headers, so no
+			 * need for the kernel side to do that.
+			 */
+
+			result = qp_host_register_user_memory(page_store,
+							      entry->produce_q,
+							      entry->consume_q);
+			if (result < VMCI_SUCCESS)
+				return result;
+
+			entry->state = VMCIQPB_ATTACHED_MEM;
+		} else {
+			entry->state = VMCIQPB_ATTACHED_NO_MEM;
+		}
+	} else if (entry->state == VMCIQPB_CREATED_NO_MEM) {
+		/*
+		 * The host side is attempting to attach to a queue
+		 * pair that doesn't have any memory associated with
+		 * it. This must be a pre NOVMVM vmx that hasn't set
+		 * the page store information yet, or a quiesced VM.
+		 */
+
+		return VMCI_ERROR_UNAVAILABLE;
+	} else {
+		/* The host side has successfully attached to a queue pair. */
+		entry->state = VMCIQPB_ATTACHED_MEM;
+	}
+
+	if (entry->state == VMCIQPB_ATTACHED_MEM) {
+		result =
+		    qp_notify_peer(true, entry->qp.handle, context_id,
+				   entry->create_id);
+		if (result < VMCI_SUCCESS)
+			pr_warn("Failed to notify peer (ID=0x%x) of attach to queue pair (handle=0x%x:0x%x)\n",
+				entry->create_id, entry->qp.handle.context,
+				entry->qp.handle.resource);
+	}
+
+	entry->attach_id = context_id;
+	entry->qp.ref_count++;
+	if (wakeup_cb) {
+		entry->wakeup_cb = wakeup_cb;
+		entry->client_data = client_data;
+	}
+
+	/*
+	 * When attaching to local queue pairs, the context already has
+	 * an entry tracking the queue pair, so don't add another one.
+	 */
+	if (!is_local)
+		vmci_ctx_qp_create(context, entry->qp.handle);
+
+	if (ent != NULL)
+		*ent = entry;
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * queue_pair_Alloc for use when setting up queue pair endpoints
+ * on the host.
+ */
+static int qp_broker_alloc(struct vmci_handle handle,
+			   u32 peer,
+			   u32 flags,
+			   u32 priv_flags,
+			   u64 produce_size,
+			   u64 consume_size,
+			   struct vmci_qp_page_store *page_store,
+			   struct vmci_ctx *context,
+			   vmci_event_release_cb wakeup_cb,
+			   void *client_data,
+			   struct qp_broker_entry **ent,
+			   bool *swap)
+{
+	const u32 context_id = vmci_ctx_get_id(context);
+	bool create;
+	struct qp_broker_entry *entry = NULL;
+	bool is_local = flags & VMCI_QPFLAG_LOCAL;
+	int result;
+
+	if (vmci_handle_is_invalid(handle) ||
+	    (flags & ~VMCI_QP_ALL_FLAGS) || is_local ||
+	    !(produce_size || consume_size) ||
+	    !context || context_id == VMCI_INVALID_ID ||
+	    handle.context == VMCI_INVALID_ID) {
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	if (page_store && !VMCI_QP_PAGESTORE_IS_WELLFORMED(page_store))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	/*
+	 * In the initial argument check, we ensure that non-vmkernel hosts
+	 * are not allowed to create local queue pairs.
+	 */
+
+	mutex_lock(&qp_broker_list.mutex);
+
+	if (!is_local && vmci_ctx_qp_exists(context, handle)) {
+		pr_devel("Context (ID=0x%x) already attached to queue pair (handle=0x%x:0x%x)\n",
+			 context_id, handle.context, handle.resource);
+		mutex_unlock(&qp_broker_list.mutex);
+		return VMCI_ERROR_ALREADY_EXISTS;
+	}
+
+	if (handle.resource != VMCI_INVALID_ID)
+		entry = qp_broker_handle_to_entry(handle);
+
+	if (!entry) {
+		create = true;
+		result =
+		    qp_broker_create(handle, peer, flags, priv_flags,
+				     produce_size, consume_size, page_store,
+				     context, wakeup_cb, client_data, ent);
+	} else {
+		create = false;
+		result =
+		    qp_broker_attach(entry, peer, flags, priv_flags,
+				     produce_size, consume_size, page_store,
+				     context, wakeup_cb, client_data, ent);
+	}
+
+	mutex_unlock(&qp_broker_list.mutex);
+
+	if (swap)
+		*swap = (context_id == VMCI_HOST_CONTEXT_ID) &&
+		    !(create && is_local);
+
+	return result;
+}
+
+/*
+ * This function implements the kernel API for allocating a queue
+ * pair.
+ */
+static int qp_alloc_host_work(struct vmci_handle *handle,
+			      struct vmci_queue **produce_q,
+			      u64 produce_size,
+			      struct vmci_queue **consume_q,
+			      u64 consume_size,
+			      u32 peer,
+			      u32 flags,
+			      u32 priv_flags,
+			      vmci_event_release_cb wakeup_cb,
+			      void *client_data)
+{
+	struct vmci_handle new_handle;
+	struct vmci_ctx *context;
+	struct qp_broker_entry *entry;
+	int result;
+	bool swap;
+
+	if (vmci_handle_is_invalid(*handle)) {
+		new_handle = vmci_make_handle(
+			VMCI_HOST_CONTEXT_ID, VMCI_INVALID_ID);
+	} else
+		new_handle = *handle;
+
+	context = vmci_ctx_get(VMCI_HOST_CONTEXT_ID);
+	entry = NULL;
+	result =
+	    qp_broker_alloc(new_handle, peer, flags, priv_flags,
+			    produce_size, consume_size, NULL, context,
+			    wakeup_cb, client_data, &entry, &swap);
+	if (result == VMCI_SUCCESS) {
+		if (swap) {
+			/*
+			 * If this is a local queue pair, the attacher
+			 * will swap around produce and consume
+			 * queues.
+			 */
+
+			*produce_q = entry->consume_q;
+			*consume_q = entry->produce_q;
+		} else {
+			*produce_q = entry->produce_q;
+			*consume_q = entry->consume_q;
+		}
+
+		*handle = vmci_resource_handle(&entry->resource);
+	} else {
+		*handle = VMCI_INVALID_HANDLE;
+		pr_devel("queue pair broker failed to alloc (result=%d)\n",
+			 result);
+	}
+	vmci_ctx_put(context);
+	return result;
+}
+
+/*
+ * Allocates a VMCI queue_pair. Only checks validity of input
+ * arguments. The real work is done in the host or guest
+ * specific function.
+ */
+int vmci_qp_alloc(struct vmci_handle *handle,
+		  struct vmci_queue **produce_q,
+		  u64 produce_size,
+		  struct vmci_queue **consume_q,
+		  u64 consume_size,
+		  u32 peer,
+		  u32 flags,
+		  u32 priv_flags,
+		  bool guest_endpoint,
+		  vmci_event_release_cb wakeup_cb,
+		  void *client_data)
+{
+	if (!handle || !produce_q || !consume_q ||
+	    (!produce_size && !consume_size) || (flags & ~VMCI_QP_ALL_FLAGS))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	if (guest_endpoint) {
+		return qp_alloc_guest_work(handle, produce_q,
+					   produce_size, consume_q,
+					   consume_size, peer,
+					   flags, priv_flags);
+	} else {
+		return qp_alloc_host_work(handle, produce_q,
+					  produce_size, consume_q,
+					  consume_size, peer, flags,
+					  priv_flags, wakeup_cb, client_data);
+	}
+}
+
+/*
+ * This function implements the host kernel API for detaching from
+ * a queue pair.
+ */
+static int qp_detatch_host_work(struct vmci_handle handle)
+{
+	int result;
+	struct vmci_ctx *context;
+
+	context = vmci_ctx_get(VMCI_HOST_CONTEXT_ID);
+
+	result = vmci_qp_broker_detach(handle, context);
+
+	vmci_ctx_put(context);
+	return result;
+}
+
+/*
+ * Detaches from a VMCI queue_pair. Only checks validity of input argument.
+ * Real work is done in the host or guest specific function.
+ */
+static int qp_detatch(struct vmci_handle handle, bool guest_endpoint)
+{
+	if (vmci_handle_is_invalid(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	if (guest_endpoint)
+		return qp_detatch_guest_work(handle);
+	else
+		return qp_detatch_host_work(handle);
+}
+
+/*
+ * Returns the entry from the head of the list. Assumes that the list is
+ * locked.
+ */
+static struct qp_entry *qp_list_get_head(struct qp_list *qp_list)
+{
+	if (!list_empty(&qp_list->head)) {
+		struct qp_entry *entry =
+		    list_first_entry(&qp_list->head, struct qp_entry,
+				     list_item);
+		return entry;
+	}
+
+	return NULL;
+}
+
+void vmci_qp_broker_exit(void)
+{
+	struct qp_entry *entry;
+	struct qp_broker_entry *be;
+
+	mutex_lock(&qp_broker_list.mutex);
+
+	while ((entry = qp_list_get_head(&qp_broker_list))) {
+		be = (struct qp_broker_entry *)entry;
+
+		qp_list_remove_entry(&qp_broker_list, entry);
+		kfree(be);
+	}
+
+	mutex_unlock(&qp_broker_list.mutex);
+}
+
+/*
+ * Requests that a queue pair be allocated with the VMCI queue
+ * pair broker. Allocates a queue pair entry if one does not
+ * exist. Attaches to one if it exists, and retrieves the page
+ * files backing that queue_pair.  Assumes that the queue pair
+ * broker lock is held.
+ */
+int vmci_qp_broker_alloc(struct vmci_handle handle,
+			 u32 peer,
+			 u32 flags,
+			 u32 priv_flags,
+			 u64 produce_size,
+			 u64 consume_size,
+			 struct vmci_qp_page_store *page_store,
+			 struct vmci_ctx *context)
+{
+	return qp_broker_alloc(handle, peer, flags, priv_flags,
+			       produce_size, consume_size,
+			       page_store, context, NULL, NULL, NULL, NULL);
+}
+
+/*
+ * VMX'en with versions lower than VMCI_VERSION_NOVMVM use a separate
+ * step to add the UVAs of the VMX mapping of the queue pair. This function
+ * provides backwards compatibility with such VMX'en, and takes care of
+ * registering the page store for a queue pair previously allocated by the
+ * VMX during create or attach. This function will move the queue pair state
+ * to either from VMCIQBP_CREATED_NO_MEM to VMCIQBP_CREATED_MEM or
+ * VMCIQBP_ATTACHED_NO_MEM to VMCIQBP_ATTACHED_MEM. If moving to the
+ * attached state with memory, the queue pair is ready to be used by the
+ * host peer, and an attached event will be generated.
+ *
+ * Assumes that the queue pair broker lock is held.
+ *
+ * This function is only used by the hosted platform, since there is no
+ * issue with backwards compatibility for vmkernel.
+ */
+int vmci_qp_broker_set_page_store(struct vmci_handle handle,
+				  u64 produce_uva,
+				  u64 consume_uva,
+				  struct vmci_ctx *context)
+{
+	struct qp_broker_entry *entry;
+	int result;
+	const u32 context_id = vmci_ctx_get_id(context);
+
+	if (vmci_handle_is_invalid(handle) || !context ||
+	    context_id == VMCI_INVALID_ID)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	/*
+	 * We only support guest to host queue pairs, so the VMX must
+	 * supply UVAs for the mapped page files.
+	 */
+
+	if (produce_uva == 0 || consume_uva == 0)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	mutex_lock(&qp_broker_list.mutex);
+
+	if (!vmci_ctx_qp_exists(context, handle)) {
+		pr_warn("Context (ID=0x%x) not attached to queue pair (handle=0x%x:0x%x)\n",
+			context_id, handle.context, handle.resource);
+		result = VMCI_ERROR_NOT_FOUND;
+		goto out;
+	}
+
+	entry = qp_broker_handle_to_entry(handle);
+	if (!entry) {
+		result = VMCI_ERROR_NOT_FOUND;
+		goto out;
+	}
+
+	/*
+	 * If I'm the owner then I can set the page store.
+	 *
+	 * Or, if a host created the queue_pair and I'm the attached peer
+	 * then I can set the page store.
+	 */
+	if (entry->create_id != context_id &&
+	    (entry->create_id != VMCI_HOST_CONTEXT_ID ||
+	     entry->attach_id != context_id)) {
+		result = VMCI_ERROR_QUEUEPAIR_NOTOWNER;
+		goto out;
+	}
+
+	if (entry->state != VMCIQPB_CREATED_NO_MEM &&
+	    entry->state != VMCIQPB_ATTACHED_NO_MEM) {
+		result = VMCI_ERROR_UNAVAILABLE;
+		goto out;
+	}
+
+	result = qp_host_get_user_memory(produce_uva, consume_uva,
+					 entry->produce_q, entry->consume_q);
+	if (result < VMCI_SUCCESS)
+		goto out;
+
+	result = qp_host_map_queues(entry->produce_q, entry->consume_q);
+	if (result < VMCI_SUCCESS) {
+		qp_host_unregister_user_memory(entry->produce_q,
+					       entry->consume_q);
+		goto out;
+	}
+
+	if (entry->state == VMCIQPB_CREATED_NO_MEM)
+		entry->state = VMCIQPB_CREATED_MEM;
+	else
+		entry->state = VMCIQPB_ATTACHED_MEM;
+
+	entry->vmci_page_files = true;
+
+	if (entry->state == VMCIQPB_ATTACHED_MEM) {
+		result =
+		    qp_notify_peer(true, handle, context_id, entry->create_id);
+		if (result < VMCI_SUCCESS) {
+			pr_warn("Failed to notify peer (ID=0x%x) of attach to queue pair (handle=0x%x:0x%x)\n",
+				entry->create_id, entry->qp.handle.context,
+				entry->qp.handle.resource);
+		}
+	}
+
+	result = VMCI_SUCCESS;
+ out:
+	mutex_unlock(&qp_broker_list.mutex);
+	return result;
+}
+
+/*
+ * Resets saved queue headers for the given QP broker
+ * entry. Should be used when guest memory becomes available
+ * again, or the guest detaches.
+ */
+static void qp_reset_saved_headers(struct qp_broker_entry *entry)
+{
+	entry->produce_q->saved_header = NULL;
+	entry->consume_q->saved_header = NULL;
+}
+
+/*
+ * The main entry point for detaching from a queue pair registered with the
+ * queue pair broker. If more than one endpoint is attached to the queue
+ * pair, the first endpoint will mainly decrement a reference count and
+ * generate a notification to its peer. The last endpoint will clean up
+ * the queue pair state registered with the broker.
+ *
+ * When a guest endpoint detaches, it will unmap and unregister the guest
+ * memory backing the queue pair. If the host is still attached, it will
+ * no longer be able to access the queue pair content.
+ *
+ * If the queue pair is already in a state where there is no memory
+ * registered for the queue pair (any *_NO_MEM state), it will transition to
+ * the VMCIQPB_SHUTDOWN_NO_MEM state. This will also happen, if a guest
+ * endpoint is the first of two endpoints to detach. If the host endpoint is
+ * the first out of two to detach, the queue pair will move to the
+ * VMCIQPB_SHUTDOWN_MEM state.
+ */
+int vmci_qp_broker_detach(struct vmci_handle handle, struct vmci_ctx *context)
+{
+	struct qp_broker_entry *entry;
+	const u32 context_id = vmci_ctx_get_id(context);
+	u32 peer_id;
+	bool is_local = false;
+	int result;
+
+	if (vmci_handle_is_invalid(handle) || !context ||
+	    context_id == VMCI_INVALID_ID) {
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	mutex_lock(&qp_broker_list.mutex);
+
+	if (!vmci_ctx_qp_exists(context, handle)) {
+		pr_devel("Context (ID=0x%x) not attached to queue pair (handle=0x%x:0x%x)\n",
+			 context_id, handle.context, handle.resource);
+		result = VMCI_ERROR_NOT_FOUND;
+		goto out;
+	}
+
+	entry = qp_broker_handle_to_entry(handle);
+	if (!entry) {
+		pr_devel("Context (ID=0x%x) reports being attached to queue pair(handle=0x%x:0x%x) that isn't present in broker\n",
+			 context_id, handle.context, handle.resource);
+		result = VMCI_ERROR_NOT_FOUND;
+		goto out;
+	}
+
+	if (context_id != entry->create_id && context_id != entry->attach_id) {
+		result = VMCI_ERROR_QUEUEPAIR_NOTATTACHED;
+		goto out;
+	}
+
+	if (context_id == entry->create_id) {
+		peer_id = entry->attach_id;
+		entry->create_id = VMCI_INVALID_ID;
+	} else {
+		peer_id = entry->create_id;
+		entry->attach_id = VMCI_INVALID_ID;
+	}
+	entry->qp.ref_count--;
+
+	is_local = entry->qp.flags & VMCI_QPFLAG_LOCAL;
+
+	if (context_id != VMCI_HOST_CONTEXT_ID) {
+		bool headers_mapped;
+
+		/*
+		 * Pre NOVMVM vmx'en may detach from a queue pair
+		 * before setting the page store, and in that case
+		 * there is no user memory to detach from. Also, more
+		 * recent VMX'en may detach from a queue pair in the
+		 * quiesced state.
+		 */
+
+		qp_acquire_queue_mutex(entry->produce_q);
+		headers_mapped = entry->produce_q->q_header ||
+		    entry->consume_q->q_header;
+		if (QPBROKERSTATE_HAS_MEM(entry)) {
+			result =
+			    qp_host_unmap_queues(INVALID_VMCI_GUEST_MEM_ID,
+						 entry->produce_q,
+						 entry->consume_q);
+			if (result < VMCI_SUCCESS)
+				pr_warn("Failed to unmap queue headers for queue pair (handle=0x%x:0x%x,result=%d)\n",
+					handle.context, handle.resource,
+					result);
+
+			qp_host_unregister_user_memory(entry->produce_q,
+						       entry->consume_q);
+
+		}
+
+		if (!headers_mapped)
+			qp_reset_saved_headers(entry);
+
+		qp_release_queue_mutex(entry->produce_q);
+
+		if (!headers_mapped && entry->wakeup_cb)
+			entry->wakeup_cb(entry->client_data);
+
+	} else {
+		if (entry->wakeup_cb) {
+			entry->wakeup_cb = NULL;
+			entry->client_data = NULL;
+		}
+	}
+
+	if (entry->qp.ref_count == 0) {
+		qp_list_remove_entry(&qp_broker_list, &entry->qp);
+
+		if (is_local)
+			kfree(entry->local_mem);
+
+		qp_cleanup_queue_mutex(entry->produce_q, entry->consume_q);
+		qp_host_free_queue(entry->produce_q, entry->qp.produce_size);
+		qp_host_free_queue(entry->consume_q, entry->qp.consume_size);
+		/* Unlink from resource hash table and free callback */
+		vmci_resource_remove(&entry->resource);
+
+		kfree(entry);
+
+		vmci_ctx_qp_destroy(context, handle);
+	} else {
+		qp_notify_peer(false, handle, context_id, peer_id);
+		if (context_id == VMCI_HOST_CONTEXT_ID &&
+		    QPBROKERSTATE_HAS_MEM(entry)) {
+			entry->state = VMCIQPB_SHUTDOWN_MEM;
+		} else {
+			entry->state = VMCIQPB_SHUTDOWN_NO_MEM;
+		}
+
+		if (!is_local)
+			vmci_ctx_qp_destroy(context, handle);
+
+	}
+	result = VMCI_SUCCESS;
+ out:
+	mutex_unlock(&qp_broker_list.mutex);
+	return result;
+}
+
+/*
+ * Establishes the necessary mappings for a queue pair given a
+ * reference to the queue pair guest memory. This is usually
+ * called when a guest is unquiesced and the VMX is allowed to
+ * map guest memory once again.
+ */
+int vmci_qp_broker_map(struct vmci_handle handle,
+		       struct vmci_ctx *context,
+		       u64 guest_mem)
+{
+	struct qp_broker_entry *entry;
+	const u32 context_id = vmci_ctx_get_id(context);
+	int result;
+
+	if (vmci_handle_is_invalid(handle) || !context ||
+	    context_id == VMCI_INVALID_ID)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	mutex_lock(&qp_broker_list.mutex);
+
+	if (!vmci_ctx_qp_exists(context, handle)) {
+		pr_devel("Context (ID=0x%x) not attached to queue pair (handle=0x%x:0x%x)\n",
+			 context_id, handle.context, handle.resource);
+		result = VMCI_ERROR_NOT_FOUND;
+		goto out;
+	}
+
+	entry = qp_broker_handle_to_entry(handle);
+	if (!entry) {
+		pr_devel("Context (ID=0x%x) reports being attached to queue pair (handle=0x%x:0x%x) that isn't present in broker\n",
+			 context_id, handle.context, handle.resource);
+		result = VMCI_ERROR_NOT_FOUND;
+		goto out;
+	}
+
+	if (context_id != entry->create_id && context_id != entry->attach_id) {
+		result = VMCI_ERROR_QUEUEPAIR_NOTATTACHED;
+		goto out;
+	}
+
+	result = VMCI_SUCCESS;
+
+	if (context_id != VMCI_HOST_CONTEXT_ID &&
+	    !QPBROKERSTATE_HAS_MEM(entry)) {
+		struct vmci_qp_page_store page_store;
+
+		page_store.pages = guest_mem;
+		page_store.len = QPE_NUM_PAGES(entry->qp);
+
+		qp_acquire_queue_mutex(entry->produce_q);
+		qp_reset_saved_headers(entry);
+		result =
+		    qp_host_register_user_memory(&page_store,
+						 entry->produce_q,
+						 entry->consume_q);
+		qp_release_queue_mutex(entry->produce_q);
+		if (result == VMCI_SUCCESS) {
+			/* Move state from *_NO_MEM to *_MEM */
+
+			entry->state++;
+
+			if (entry->wakeup_cb)
+				entry->wakeup_cb(entry->client_data);
+		}
+	}
+
+ out:
+	mutex_unlock(&qp_broker_list.mutex);
+	return result;
+}
+
+/*
+ * Saves a snapshot of the queue headers for the given QP broker
+ * entry. Should be used when guest memory is unmapped.
+ * Results:
+ * VMCI_SUCCESS on success, appropriate error code if guest memory
+ * can't be accessed..
+ */
+static int qp_save_headers(struct qp_broker_entry *entry)
+{
+	int result;
+
+	if (entry->produce_q->saved_header != NULL &&
+	    entry->consume_q->saved_header != NULL) {
+		/*
+		 *  If the headers have already been saved, we don't need to do
+		 *  it again, and we don't want to map in the headers
+		 *  unnecessarily.
+		 */
+
+		return VMCI_SUCCESS;
+	}
+
+	if (NULL == entry->produce_q->q_header ||
+	    NULL == entry->consume_q->q_header) {
+		result = qp_host_map_queues(entry->produce_q, entry->consume_q);
+		if (result < VMCI_SUCCESS)
+			return result;
+	}
+
+	memcpy(&entry->saved_produce_q, entry->produce_q->q_header,
+	       sizeof(entry->saved_produce_q));
+	entry->produce_q->saved_header = &entry->saved_produce_q;
+	memcpy(&entry->saved_consume_q, entry->consume_q->q_header,
+	       sizeof(entry->saved_consume_q));
+	entry->consume_q->saved_header = &entry->saved_consume_q;
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Removes all references to the guest memory of a given queue pair, and
+ * will move the queue pair from state *_MEM to *_NO_MEM. It is usually
+ * called when a VM is being quiesced where access to guest memory should
+ * avoided.
+ */
+int vmci_qp_broker_unmap(struct vmci_handle handle,
+			 struct vmci_ctx *context,
+			 u32 gid)
+{
+	struct qp_broker_entry *entry;
+	const u32 context_id = vmci_ctx_get_id(context);
+	int result;
+
+	if (vmci_handle_is_invalid(handle) || !context ||
+	    context_id == VMCI_INVALID_ID)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	mutex_lock(&qp_broker_list.mutex);
+
+	if (!vmci_ctx_qp_exists(context, handle)) {
+		pr_devel("Context (ID=0x%x) not attached to queue pair (handle=0x%x:0x%x)\n",
+			 context_id, handle.context, handle.resource);
+		result = VMCI_ERROR_NOT_FOUND;
+		goto out;
+	}
+
+	entry = qp_broker_handle_to_entry(handle);
+	if (!entry) {
+		pr_devel("Context (ID=0x%x) reports being attached to queue pair (handle=0x%x:0x%x) that isn't present in broker\n",
+			 context_id, handle.context, handle.resource);
+		result = VMCI_ERROR_NOT_FOUND;
+		goto out;
+	}
+
+	if (context_id != entry->create_id && context_id != entry->attach_id) {
+		result = VMCI_ERROR_QUEUEPAIR_NOTATTACHED;
+		goto out;
+	}
+
+	if (context_id != VMCI_HOST_CONTEXT_ID &&
+	    QPBROKERSTATE_HAS_MEM(entry)) {
+		qp_acquire_queue_mutex(entry->produce_q);
+		result = qp_save_headers(entry);
+		if (result < VMCI_SUCCESS)
+			pr_warn("Failed to save queue headers for queue pair (handle=0x%x:0x%x,result=%d)\n",
+				handle.context, handle.resource, result);
+
+		qp_host_unmap_queues(gid, entry->produce_q, entry->consume_q);
+
+		/*
+		 * On hosted, when we unmap queue pairs, the VMX will also
+		 * unmap the guest memory, so we invalidate the previously
+		 * registered memory. If the queue pair is mapped again at a
+		 * later point in time, we will need to reregister the user
+		 * memory with a possibly new user VA.
+		 */
+		qp_host_unregister_user_memory(entry->produce_q,
+					       entry->consume_q);
+
+		/*
+		 * Move state from *_MEM to *_NO_MEM.
+		 */
+		entry->state--;
+
+		qp_release_queue_mutex(entry->produce_q);
+	}
+
+	result = VMCI_SUCCESS;
+
+ out:
+	mutex_unlock(&qp_broker_list.mutex);
+	return result;
+}
+
+/*
+ * Destroys all guest queue pair endpoints. If active guest queue
+ * pairs still exist, hypercalls to attempt detach from these
+ * queue pairs will be made. Any failure to detach is silently
+ * ignored.
+ */
+void vmci_qp_guest_endpoints_exit(void)
+{
+	struct qp_entry *entry;
+	struct qp_guest_endpoint *ep;
+
+	mutex_lock(&qp_guest_endpoints.mutex);
+
+	while ((entry = qp_list_get_head(&qp_guest_endpoints))) {
+		ep = (struct qp_guest_endpoint *)entry;
+
+		/* Don't make a hypercall for local queue_pairs. */
+		if (!(entry->flags & VMCI_QPFLAG_LOCAL))
+			qp_detatch_hypercall(entry->handle);
+
+		/* We cannot fail the exit, so let's reset ref_count. */
+		entry->ref_count = 0;
+		qp_list_remove_entry(&qp_guest_endpoints, entry);
+
+		qp_guest_endpoint_destroy(ep);
+	}
+
+	mutex_unlock(&qp_guest_endpoints.mutex);
+}
+
+/*
+ * Helper routine that will lock the queue pair before subsequent
+ * operations.
+ * Note: Non-blocking on the host side is currently only implemented in ESX.
+ * Since non-blocking isn't yet implemented on the host personality we
+ * have no reason to acquire a spin lock.  So to avoid the use of an
+ * unnecessary lock only acquire the mutex if we can block.
+ */
+static void qp_lock(const struct vmci_qp *qpair)
+{
+	qp_acquire_queue_mutex(qpair->produce_q);
+}
+
+/*
+ * Helper routine that unlocks the queue pair after calling
+ * qp_lock.
+ */
+static void qp_unlock(const struct vmci_qp *qpair)
+{
+	qp_release_queue_mutex(qpair->produce_q);
+}
+
+/*
+ * The queue headers may not be mapped at all times. If a queue is
+ * currently not mapped, it will be attempted to do so.
+ */
+static int qp_map_queue_headers(struct vmci_queue *produce_q,
+				struct vmci_queue *consume_q)
+{
+	int result;
+
+	if (NULL == produce_q->q_header || NULL == consume_q->q_header) {
+		result = qp_host_map_queues(produce_q, consume_q);
+		if (result < VMCI_SUCCESS)
+			return (produce_q->saved_header &&
+				consume_q->saved_header) ?
+			    VMCI_ERROR_QUEUEPAIR_NOT_READY :
+			    VMCI_ERROR_QUEUEPAIR_NOTATTACHED;
+	}
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Helper routine that will retrieve the produce and consume
+ * headers of a given queue pair. If the guest memory of the
+ * queue pair is currently not available, the saved queue headers
+ * will be returned, if these are available.
+ */
+static int qp_get_queue_headers(const struct vmci_qp *qpair,
+				struct vmci_queue_header **produce_q_header,
+				struct vmci_queue_header **consume_q_header)
+{
+	int result;
+
+	result = qp_map_queue_headers(qpair->produce_q, qpair->consume_q);
+	if (result == VMCI_SUCCESS) {
+		*produce_q_header = qpair->produce_q->q_header;
+		*consume_q_header = qpair->consume_q->q_header;
+	} else if (qpair->produce_q->saved_header &&
+		   qpair->consume_q->saved_header) {
+		*produce_q_header = qpair->produce_q->saved_header;
+		*consume_q_header = qpair->consume_q->saved_header;
+		result = VMCI_SUCCESS;
+	}
+
+	return result;
+}
+
+/*
+ * Callback from VMCI queue pair broker indicating that a queue
+ * pair that was previously not ready, now either is ready or
+ * gone forever.
+ */
+static int qp_wakeup_cb(void *client_data)
+{
+	struct vmci_qp *qpair = (struct vmci_qp *)client_data;
+
+	qp_lock(qpair);
+	while (qpair->blocked > 0) {
+		qpair->blocked--;
+		qpair->generation++;
+		wake_up(&qpair->event);
+	}
+	qp_unlock(qpair);
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ * Makes the calling thread wait for the queue pair to become
+ * ready for host side access.  Returns true when thread is
+ * woken up after queue pair state change, false otherwise.
+ */
+static bool qp_wait_for_ready_queue(struct vmci_qp *qpair)
+{
+	unsigned int generation;
+
+	qpair->blocked++;
+	generation = qpair->generation;
+	qp_unlock(qpair);
+	wait_event(qpair->event, generation != qpair->generation);
+	qp_lock(qpair);
+
+	return true;
+}
+
+/*
+ * Enqueues a given buffer to the produce queue using the provided
+ * function. As many bytes as possible (space available in the queue)
+ * are enqueued.  Assumes the queue->mutex has been acquired.  Returns
+ * VMCI_ERROR_QUEUEPAIR_NOSPACE if no space was available to enqueue
+ * data, VMCI_ERROR_INVALID_SIZE, if any queue pointer is outside the
+ * queue (as defined by the queue size), VMCI_ERROR_INVALID_ARGS, if
+ * an error occured when accessing the buffer,
+ * VMCI_ERROR_QUEUEPAIR_NOTATTACHED, if the queue pair pages aren't
+ * available.  Otherwise, the number of bytes written to the queue is
+ * returned.  Updates the tail pointer of the produce queue.
+ */
+static ssize_t qp_enqueue_locked(struct vmci_queue *produce_q,
+				 struct vmci_queue *consume_q,
+				 const u64 produce_q_size,
+				 struct iov_iter *from)
+{
+	s64 free_space;
+	u64 tail;
+	size_t buf_size = iov_iter_count(from);
+	size_t written;
+	ssize_t result;
+
+	result = qp_map_queue_headers(produce_q, consume_q);
+	if (unlikely(result != VMCI_SUCCESS))
+		return result;
+
+	free_space = vmci_q_header_free_space(produce_q->q_header,
+					      consume_q->q_header,
+					      produce_q_size);
+	if (free_space == 0)
+		return VMCI_ERROR_QUEUEPAIR_NOSPACE;
+
+	if (free_space < VMCI_SUCCESS)
+		return (ssize_t) free_space;
+
+	written = (size_t) (free_space > buf_size ? buf_size : free_space);
+	tail = vmci_q_header_producer_tail(produce_q->q_header);
+	if (likely(tail + written < produce_q_size)) {
+		result = qp_memcpy_to_queue_iter(produce_q, tail, from, written);
+	} else {
+		/* Tail pointer wraps around. */
+
+		const size_t tmp = (size_t) (produce_q_size - tail);
+
+		result = qp_memcpy_to_queue_iter(produce_q, tail, from, tmp);
+		if (result >= VMCI_SUCCESS)
+			result = qp_memcpy_to_queue_iter(produce_q, 0, from,
+						 written - tmp);
+	}
+
+	if (result < VMCI_SUCCESS)
+		return result;
+
+	vmci_q_header_add_producer_tail(produce_q->q_header, written,
+					produce_q_size);
+	return written;
+}
+
+/*
+ * Dequeues data (if available) from the given consume queue. Writes data
+ * to the user provided buffer using the provided function.
+ * Assumes the queue->mutex has been acquired.
+ * Results:
+ * VMCI_ERROR_QUEUEPAIR_NODATA if no data was available to dequeue.
+ * VMCI_ERROR_INVALID_SIZE, if any queue pointer is outside the queue
+ * (as defined by the queue size).
+ * VMCI_ERROR_INVALID_ARGS, if an error occured when accessing the buffer.
+ * Otherwise the number of bytes dequeued is returned.
+ * Side effects:
+ * Updates the head pointer of the consume queue.
+ */
+static ssize_t qp_dequeue_locked(struct vmci_queue *produce_q,
+				 struct vmci_queue *consume_q,
+				 const u64 consume_q_size,
+				 struct iov_iter *to,
+				 bool update_consumer)
+{
+	size_t buf_size = iov_iter_count(to);
+	s64 buf_ready;
+	u64 head;
+	size_t read;
+	ssize_t result;
+
+	result = qp_map_queue_headers(produce_q, consume_q);
+	if (unlikely(result != VMCI_SUCCESS))
+		return result;
+
+	buf_ready = vmci_q_header_buf_ready(consume_q->q_header,
+					    produce_q->q_header,
+					    consume_q_size);
+	if (buf_ready == 0)
+		return VMCI_ERROR_QUEUEPAIR_NODATA;
+
+	if (buf_ready < VMCI_SUCCESS)
+		return (ssize_t) buf_ready;
+
+	read = (size_t) (buf_ready > buf_size ? buf_size : buf_ready);
+	head = vmci_q_header_consumer_head(produce_q->q_header);
+	if (likely(head + read < consume_q_size)) {
+		result = qp_memcpy_from_queue_iter(to, consume_q, head, read);
+	} else {
+		/* Head pointer wraps around. */
+
+		const size_t tmp = (size_t) (consume_q_size - head);
+
+		result = qp_memcpy_from_queue_iter(to, consume_q, head, tmp);
+		if (result >= VMCI_SUCCESS)
+			result = qp_memcpy_from_queue_iter(to, consume_q, 0,
+						   read - tmp);
+
+	}
+
+	if (result < VMCI_SUCCESS)
+		return result;
+
+	if (update_consumer)
+		vmci_q_header_add_consumer_head(produce_q->q_header,
+						read, consume_q_size);
+
+	return read;
+}
+
+/*
+ * vmci_qpair_alloc() - Allocates a queue pair.
+ * @qpair:      Pointer for the new vmci_qp struct.
+ * @handle:     Handle to track the resource.
+ * @produce_qsize:      Desired size of the producer queue.
+ * @consume_qsize:      Desired size of the consumer queue.
+ * @peer:       ContextID of the peer.
+ * @flags:      VMCI flags.
+ * @priv_flags: VMCI priviledge flags.
+ *
+ * This is the client interface for allocating the memory for a
+ * vmci_qp structure and then attaching to the underlying
+ * queue.  If an error occurs allocating the memory for the
+ * vmci_qp structure no attempt is made to attach.  If an
+ * error occurs attaching, then the structure is freed.
+ */
+int vmci_qpair_alloc(struct vmci_qp **qpair,
+		     struct vmci_handle *handle,
+		     u64 produce_qsize,
+		     u64 consume_qsize,
+		     u32 peer,
+		     u32 flags,
+		     u32 priv_flags)
+{
+	struct vmci_qp *my_qpair;
+	int retval;
+	struct vmci_handle src = VMCI_INVALID_HANDLE;
+	struct vmci_handle dst = vmci_make_handle(peer, VMCI_INVALID_ID);
+	enum vmci_route route;
+	vmci_event_release_cb wakeup_cb;
+	void *client_data;
+
+	/*
+	 * Restrict the size of a queuepair.  The device already
+	 * enforces a limit on the total amount of memory that can be
+	 * allocated to queuepairs for a guest.  However, we try to
+	 * allocate this memory before we make the queuepair
+	 * allocation hypercall.  On Linux, we allocate each page
+	 * separately, which means rather than fail, the guest will
+	 * thrash while it tries to allocate, and will become
+	 * increasingly unresponsive to the point where it appears to
+	 * be hung.  So we place a limit on the size of an individual
+	 * queuepair here, and leave the device to enforce the
+	 * restriction on total queuepair memory.  (Note that this
+	 * doesn't prevent all cases; a user with only this much
+	 * physical memory could still get into trouble.)  The error
+	 * used by the device is NO_RESOURCES, so use that here too.
+	 */
+
+	if (produce_qsize + consume_qsize < max(produce_qsize, consume_qsize) ||
+	    produce_qsize + consume_qsize > VMCI_MAX_GUEST_QP_MEMORY)
+		return VMCI_ERROR_NO_RESOURCES;
+
+	retval = vmci_route(&src, &dst, false, &route);
+	if (retval < VMCI_SUCCESS)
+		route = vmci_guest_code_active() ?
+		    VMCI_ROUTE_AS_GUEST : VMCI_ROUTE_AS_HOST;
+
+	if (flags & (VMCI_QPFLAG_NONBLOCK | VMCI_QPFLAG_PINNED)) {
+		pr_devel("NONBLOCK OR PINNED set");
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	my_qpair = kzalloc(sizeof(*my_qpair), GFP_KERNEL);
+	if (!my_qpair)
+		return VMCI_ERROR_NO_MEM;
+
+	my_qpair->produce_q_size = produce_qsize;
+	my_qpair->consume_q_size = consume_qsize;
+	my_qpair->peer = peer;
+	my_qpair->flags = flags;
+	my_qpair->priv_flags = priv_flags;
+
+	wakeup_cb = NULL;
+	client_data = NULL;
+
+	if (VMCI_ROUTE_AS_HOST == route) {
+		my_qpair->guest_endpoint = false;
+		if (!(flags & VMCI_QPFLAG_LOCAL)) {
+			my_qpair->blocked = 0;
+			my_qpair->generation = 0;
+			init_waitqueue_head(&my_qpair->event);
+			wakeup_cb = qp_wakeup_cb;
+			client_data = (void *)my_qpair;
+		}
+	} else {
+		my_qpair->guest_endpoint = true;
+	}
+
+	retval = vmci_qp_alloc(handle,
+			       &my_qpair->produce_q,
+			       my_qpair->produce_q_size,
+			       &my_qpair->consume_q,
+			       my_qpair->consume_q_size,
+			       my_qpair->peer,
+			       my_qpair->flags,
+			       my_qpair->priv_flags,
+			       my_qpair->guest_endpoint,
+			       wakeup_cb, client_data);
+
+	if (retval < VMCI_SUCCESS) {
+		kfree(my_qpair);
+		return retval;
+	}
+
+	*qpair = my_qpair;
+	my_qpair->handle = *handle;
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_alloc);
+
+/*
+ * vmci_qpair_detach() - Detatches the client from a queue pair.
+ * @qpair:      Reference of a pointer to the qpair struct.
+ *
+ * This is the client interface for detaching from a VMCIQPair.
+ * Note that this routine will free the memory allocated for the
+ * vmci_qp structure too.
+ */
+int vmci_qpair_detach(struct vmci_qp **qpair)
+{
+	int result;
+	struct vmci_qp *old_qpair;
+
+	if (!qpair || !(*qpair))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	old_qpair = *qpair;
+	result = qp_detatch(old_qpair->handle, old_qpair->guest_endpoint);
+
+	/*
+	 * The guest can fail to detach for a number of reasons, and
+	 * if it does so, it will cleanup the entry (if there is one).
+	 * The host can fail too, but it won't cleanup the entry
+	 * immediately, it will do that later when the context is
+	 * freed.  Either way, we need to release the qpair struct
+	 * here; there isn't much the caller can do, and we don't want
+	 * to leak.
+	 */
+
+	memset(old_qpair, 0, sizeof(*old_qpair));
+	old_qpair->handle = VMCI_INVALID_HANDLE;
+	old_qpair->peer = VMCI_INVALID_ID;
+	kfree(old_qpair);
+	*qpair = NULL;
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_detach);
+
+/*
+ * vmci_qpair_get_produce_indexes() - Retrieves the indexes of the producer.
+ * @qpair:      Pointer to the queue pair struct.
+ * @producer_tail:      Reference used for storing producer tail index.
+ * @consumer_head:      Reference used for storing the consumer head index.
+ *
+ * This is the client interface for getting the current indexes of the
+ * QPair from the point of the view of the caller as the producer.
+ */
+int vmci_qpair_get_produce_indexes(const struct vmci_qp *qpair,
+				   u64 *producer_tail,
+				   u64 *consumer_head)
+{
+	struct vmci_queue_header *produce_q_header;
+	struct vmci_queue_header *consume_q_header;
+	int result;
+
+	if (!qpair)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	qp_lock(qpair);
+	result =
+	    qp_get_queue_headers(qpair, &produce_q_header, &consume_q_header);
+	if (result == VMCI_SUCCESS)
+		vmci_q_header_get_pointers(produce_q_header, consume_q_header,
+					   producer_tail, consumer_head);
+	qp_unlock(qpair);
+
+	if (result == VMCI_SUCCESS &&
+	    ((producer_tail && *producer_tail >= qpair->produce_q_size) ||
+	     (consumer_head && *consumer_head >= qpair->produce_q_size)))
+		return VMCI_ERROR_INVALID_SIZE;
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_get_produce_indexes);
+
+/*
+ * vmci_qpair_get_consume_indexes() - Retrieves the indexes of the consumer.
+ * @qpair:      Pointer to the queue pair struct.
+ * @consumer_tail:      Reference used for storing consumer tail index.
+ * @producer_head:      Reference used for storing the producer head index.
+ *
+ * This is the client interface for getting the current indexes of the
+ * QPair from the point of the view of the caller as the consumer.
+ */
+int vmci_qpair_get_consume_indexes(const struct vmci_qp *qpair,
+				   u64 *consumer_tail,
+				   u64 *producer_head)
+{
+	struct vmci_queue_header *produce_q_header;
+	struct vmci_queue_header *consume_q_header;
+	int result;
+
+	if (!qpair)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	qp_lock(qpair);
+	result =
+	    qp_get_queue_headers(qpair, &produce_q_header, &consume_q_header);
+	if (result == VMCI_SUCCESS)
+		vmci_q_header_get_pointers(consume_q_header, produce_q_header,
+					   consumer_tail, producer_head);
+	qp_unlock(qpair);
+
+	if (result == VMCI_SUCCESS &&
+	    ((consumer_tail && *consumer_tail >= qpair->consume_q_size) ||
+	     (producer_head && *producer_head >= qpair->consume_q_size)))
+		return VMCI_ERROR_INVALID_SIZE;
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_get_consume_indexes);
+
+/*
+ * vmci_qpair_produce_free_space() - Retrieves free space in producer queue.
+ * @qpair:      Pointer to the queue pair struct.
+ *
+ * This is the client interface for getting the amount of free
+ * space in the QPair from the point of the view of the caller as
+ * the producer which is the common case.  Returns < 0 if err, else
+ * available bytes into which data can be enqueued if > 0.
+ */
+s64 vmci_qpair_produce_free_space(const struct vmci_qp *qpair)
+{
+	struct vmci_queue_header *produce_q_header;
+	struct vmci_queue_header *consume_q_header;
+	s64 result;
+
+	if (!qpair)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	qp_lock(qpair);
+	result =
+	    qp_get_queue_headers(qpair, &produce_q_header, &consume_q_header);
+	if (result == VMCI_SUCCESS)
+		result = vmci_q_header_free_space(produce_q_header,
+						  consume_q_header,
+						  qpair->produce_q_size);
+	else
+		result = 0;
+
+	qp_unlock(qpair);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_produce_free_space);
+
+/*
+ * vmci_qpair_consume_free_space() - Retrieves free space in consumer queue.
+ * @qpair:      Pointer to the queue pair struct.
+ *
+ * This is the client interface for getting the amount of free
+ * space in the QPair from the point of the view of the caller as
+ * the consumer which is not the common case.  Returns < 0 if err, else
+ * available bytes into which data can be enqueued if > 0.
+ */
+s64 vmci_qpair_consume_free_space(const struct vmci_qp *qpair)
+{
+	struct vmci_queue_header *produce_q_header;
+	struct vmci_queue_header *consume_q_header;
+	s64 result;
+
+	if (!qpair)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	qp_lock(qpair);
+	result =
+	    qp_get_queue_headers(qpair, &produce_q_header, &consume_q_header);
+	if (result == VMCI_SUCCESS)
+		result = vmci_q_header_free_space(consume_q_header,
+						  produce_q_header,
+						  qpair->consume_q_size);
+	else
+		result = 0;
+
+	qp_unlock(qpair);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_consume_free_space);
+
+/*
+ * vmci_qpair_produce_buf_ready() - Gets bytes ready to read from
+ * producer queue.
+ * @qpair:      Pointer to the queue pair struct.
+ *
+ * This is the client interface for getting the amount of
+ * enqueued data in the QPair from the point of the view of the
+ * caller as the producer which is not the common case.  Returns < 0 if err,
+ * else available bytes that may be read.
+ */
+s64 vmci_qpair_produce_buf_ready(const struct vmci_qp *qpair)
+{
+	struct vmci_queue_header *produce_q_header;
+	struct vmci_queue_header *consume_q_header;
+	s64 result;
+
+	if (!qpair)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	qp_lock(qpair);
+	result =
+	    qp_get_queue_headers(qpair, &produce_q_header, &consume_q_header);
+	if (result == VMCI_SUCCESS)
+		result = vmci_q_header_buf_ready(produce_q_header,
+						 consume_q_header,
+						 qpair->produce_q_size);
+	else
+		result = 0;
+
+	qp_unlock(qpair);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_produce_buf_ready);
+
+/*
+ * vmci_qpair_consume_buf_ready() - Gets bytes ready to read from
+ * consumer queue.
+ * @qpair:      Pointer to the queue pair struct.
+ *
+ * This is the client interface for getting the amount of
+ * enqueued data in the QPair from the point of the view of the
+ * caller as the consumer which is the normal case.  Returns < 0 if err,
+ * else available bytes that may be read.
+ */
+s64 vmci_qpair_consume_buf_ready(const struct vmci_qp *qpair)
+{
+	struct vmci_queue_header *produce_q_header;
+	struct vmci_queue_header *consume_q_header;
+	s64 result;
+
+	if (!qpair)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	qp_lock(qpair);
+	result =
+	    qp_get_queue_headers(qpair, &produce_q_header, &consume_q_header);
+	if (result == VMCI_SUCCESS)
+		result = vmci_q_header_buf_ready(consume_q_header,
+						 produce_q_header,
+						 qpair->consume_q_size);
+	else
+		result = 0;
+
+	qp_unlock(qpair);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_consume_buf_ready);
+
+/*
+ * vmci_qpair_enqueue() - Throw data on the queue.
+ * @qpair:      Pointer to the queue pair struct.
+ * @buf:        Pointer to buffer containing data
+ * @buf_size:   Length of buffer.
+ * @buf_type:   Buffer type (Unused).
+ *
+ * This is the client interface for enqueueing data into the queue.
+ * Returns number of bytes enqueued or < 0 on error.
+ */
+ssize_t vmci_qpair_enqueue(struct vmci_qp *qpair,
+			   const void *buf,
+			   size_t buf_size,
+			   int buf_type)
+{
+	ssize_t result;
+	struct iov_iter from;
+	struct kvec v = {.iov_base = (void *)buf, .iov_len = buf_size};
+
+	if (!qpair || !buf)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	iov_iter_kvec(&from, WRITE | ITER_KVEC, &v, 1, buf_size);
+
+	qp_lock(qpair);
+
+	do {
+		result = qp_enqueue_locked(qpair->produce_q,
+					   qpair->consume_q,
+					   qpair->produce_q_size,
+					   &from);
+
+		if (result == VMCI_ERROR_QUEUEPAIR_NOT_READY &&
+		    !qp_wait_for_ready_queue(qpair))
+			result = VMCI_ERROR_WOULD_BLOCK;
+
+	} while (result == VMCI_ERROR_QUEUEPAIR_NOT_READY);
+
+	qp_unlock(qpair);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_enqueue);
+
+/*
+ * vmci_qpair_dequeue() - Get data from the queue.
+ * @qpair:      Pointer to the queue pair struct.
+ * @buf:        Pointer to buffer for the data
+ * @buf_size:   Length of buffer.
+ * @buf_type:   Buffer type (Unused).
+ *
+ * This is the client interface for dequeueing data from the queue.
+ * Returns number of bytes dequeued or < 0 on error.
+ */
+ssize_t vmci_qpair_dequeue(struct vmci_qp *qpair,
+			   void *buf,
+			   size_t buf_size,
+			   int buf_type)
+{
+	ssize_t result;
+	struct iov_iter to;
+	struct kvec v = {.iov_base = buf, .iov_len = buf_size};
+
+	if (!qpair || !buf)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	iov_iter_kvec(&to, READ | ITER_KVEC, &v, 1, buf_size);
+
+	qp_lock(qpair);
+
+	do {
+		result = qp_dequeue_locked(qpair->produce_q,
+					   qpair->consume_q,
+					   qpair->consume_q_size,
+					   &to, true);
+
+		if (result == VMCI_ERROR_QUEUEPAIR_NOT_READY &&
+		    !qp_wait_for_ready_queue(qpair))
+			result = VMCI_ERROR_WOULD_BLOCK;
+
+	} while (result == VMCI_ERROR_QUEUEPAIR_NOT_READY);
+
+	qp_unlock(qpair);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_dequeue);
+
+/*
+ * vmci_qpair_peek() - Peek at the data in the queue.
+ * @qpair:      Pointer to the queue pair struct.
+ * @buf:        Pointer to buffer for the data
+ * @buf_size:   Length of buffer.
+ * @buf_type:   Buffer type (Unused on Linux).
+ *
+ * This is the client interface for peeking into a queue.  (I.e.,
+ * copy data from the queue without updating the head pointer.)
+ * Returns number of bytes dequeued or < 0 on error.
+ */
+ssize_t vmci_qpair_peek(struct vmci_qp *qpair,
+			void *buf,
+			size_t buf_size,
+			int buf_type)
+{
+	struct iov_iter to;
+	struct kvec v = {.iov_base = buf, .iov_len = buf_size};
+	ssize_t result;
+
+	if (!qpair || !buf)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	iov_iter_kvec(&to, READ | ITER_KVEC, &v, 1, buf_size);
+
+	qp_lock(qpair);
+
+	do {
+		result = qp_dequeue_locked(qpair->produce_q,
+					   qpair->consume_q,
+					   qpair->consume_q_size,
+					   &to, false);
+
+		if (result == VMCI_ERROR_QUEUEPAIR_NOT_READY &&
+		    !qp_wait_for_ready_queue(qpair))
+			result = VMCI_ERROR_WOULD_BLOCK;
+
+	} while (result == VMCI_ERROR_QUEUEPAIR_NOT_READY);
+
+	qp_unlock(qpair);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_peek);
+
+/*
+ * vmci_qpair_enquev() - Throw data on the queue using iov.
+ * @qpair:      Pointer to the queue pair struct.
+ * @iov:        Pointer to buffer containing data
+ * @iov_size:   Length of buffer.
+ * @buf_type:   Buffer type (Unused).
+ *
+ * This is the client interface for enqueueing data into the queue.
+ * This function uses IO vectors to handle the work. Returns number
+ * of bytes enqueued or < 0 on error.
+ */
+ssize_t vmci_qpair_enquev(struct vmci_qp *qpair,
+			  struct msghdr *msg,
+			  size_t iov_size,
+			  int buf_type)
+{
+	ssize_t result;
+
+	if (!qpair)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	qp_lock(qpair);
+
+	do {
+		result = qp_enqueue_locked(qpair->produce_q,
+					   qpair->consume_q,
+					   qpair->produce_q_size,
+					   &msg->msg_iter);
+
+		if (result == VMCI_ERROR_QUEUEPAIR_NOT_READY &&
+		    !qp_wait_for_ready_queue(qpair))
+			result = VMCI_ERROR_WOULD_BLOCK;
+
+	} while (result == VMCI_ERROR_QUEUEPAIR_NOT_READY);
+
+	qp_unlock(qpair);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_enquev);
+
+/*
+ * vmci_qpair_dequev() - Get data from the queue using iov.
+ * @qpair:      Pointer to the queue pair struct.
+ * @iov:        Pointer to buffer for the data
+ * @iov_size:   Length of buffer.
+ * @buf_type:   Buffer type (Unused).
+ *
+ * This is the client interface for dequeueing data from the queue.
+ * This function uses IO vectors to handle the work. Returns number
+ * of bytes dequeued or < 0 on error.
+ */
+ssize_t vmci_qpair_dequev(struct vmci_qp *qpair,
+			  struct msghdr *msg,
+			  size_t iov_size,
+			  int buf_type)
+{
+	ssize_t result;
+
+	if (!qpair)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	qp_lock(qpair);
+
+	do {
+		result = qp_dequeue_locked(qpair->produce_q,
+					   qpair->consume_q,
+					   qpair->consume_q_size,
+					   &msg->msg_iter, true);
+
+		if (result == VMCI_ERROR_QUEUEPAIR_NOT_READY &&
+		    !qp_wait_for_ready_queue(qpair))
+			result = VMCI_ERROR_WOULD_BLOCK;
+
+	} while (result == VMCI_ERROR_QUEUEPAIR_NOT_READY);
+
+	qp_unlock(qpair);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_dequev);
+
+/*
+ * vmci_qpair_peekv() - Peek at the data in the queue using iov.
+ * @qpair:      Pointer to the queue pair struct.
+ * @iov:        Pointer to buffer for the data
+ * @iov_size:   Length of buffer.
+ * @buf_type:   Buffer type (Unused on Linux).
+ *
+ * This is the client interface for peeking into a queue.  (I.e.,
+ * copy data from the queue without updating the head pointer.)
+ * This function uses IO vectors to handle the work. Returns number
+ * of bytes peeked or < 0 on error.
+ */
+ssize_t vmci_qpair_peekv(struct vmci_qp *qpair,
+			 struct msghdr *msg,
+			 size_t iov_size,
+			 int buf_type)
+{
+	ssize_t result;
+
+	if (!qpair)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	qp_lock(qpair);
+
+	do {
+		result = qp_dequeue_locked(qpair->produce_q,
+					   qpair->consume_q,
+					   qpair->consume_q_size,
+					   &msg->msg_iter, false);
+
+		if (result == VMCI_ERROR_QUEUEPAIR_NOT_READY &&
+		    !qp_wait_for_ready_queue(qpair))
+			result = VMCI_ERROR_WOULD_BLOCK;
+
+	} while (result == VMCI_ERROR_QUEUEPAIR_NOT_READY);
+
+	qp_unlock(qpair);
+	return result;
+}
+EXPORT_SYMBOL_GPL(vmci_qpair_peekv);
diff --git a/drivers/misc/vmw_vmci/vmci_queue_pair.h b/drivers/misc/vmw_vmci/vmci_queue_pair.h
new file mode 100644
index 000000000..ed177f04e
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_queue_pair.h
@@ -0,0 +1,173 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#ifndef _VMCI_QUEUE_PAIR_H_
+#define _VMCI_QUEUE_PAIR_H_
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/types.h>
+
+#include "vmci_context.h"
+
+/* Callback needed for correctly waiting on events. */
+typedef int (*vmci_event_release_cb) (void *client_data);
+
+/* Guest device port I/O. */
+struct ppn_set {
+	u64 num_produce_pages;
+	u64 num_consume_pages;
+	u32 *produce_ppns;
+	u32 *consume_ppns;
+	bool initialized;
+};
+
+/* VMCIqueue_pairAllocInfo */
+struct vmci_qp_alloc_info {
+	struct vmci_handle handle;
+	u32 peer;
+	u32 flags;
+	u64 produce_size;
+	u64 consume_size;
+	u64 ppn_va;	/* Start VA of queue pair PPNs. */
+	u64 num_ppns;
+	s32 result;
+	u32 version;
+};
+
+/* VMCIqueue_pairSetVAInfo */
+struct vmci_qp_set_va_info {
+	struct vmci_handle handle;
+	u64 va;		/* Start VA of queue pair PPNs. */
+	u64 num_ppns;
+	u32 version;
+	s32 result;
+};
+
+/*
+ * For backwards compatibility, here is a version of the
+ * VMCIqueue_pairPageFileInfo before host support end-points was added.
+ * Note that the current version of that structure requires VMX to
+ * pass down the VA of the mapped file.  Before host support was added
+ * there was nothing of the sort.  So, when the driver sees the ioctl
+ * with a parameter that is the sizeof
+ * VMCIqueue_pairPageFileInfo_NoHostQP then it can infer that the version
+ * of VMX running can't attach to host end points because it doesn't
+ * provide the VA of the mapped files.
+ *
+ * The Linux driver doesn't get an indication of the size of the
+ * structure passed down from user space.  So, to fix a long standing
+ * but unfiled bug, the _pad field has been renamed to version.
+ * Existing versions of VMX always initialize the PageFileInfo
+ * structure so that _pad, er, version is set to 0.
+ *
+ * A version value of 1 indicates that the size of the structure has
+ * been increased to include two UVA's: produce_uva and consume_uva.
+ * These UVA's are of the mmap()'d queue contents backing files.
+ *
+ * In addition, if when VMX is sending down the
+ * VMCIqueue_pairPageFileInfo structure it gets an error then it will
+ * try again with the _NoHostQP version of the file to see if an older
+ * VMCI kernel module is running.
+ */
+
+/* VMCIqueue_pairPageFileInfo */
+struct vmci_qp_page_file_info {
+	struct vmci_handle handle;
+	u64 produce_page_file;	  /* User VA. */
+	u64 consume_page_file;	  /* User VA. */
+	u64 produce_page_file_size;  /* Size of the file name array. */
+	u64 consume_page_file_size;  /* Size of the file name array. */
+	s32 result;
+	u32 version;	/* Was _pad. */
+	u64 produce_va;	/* User VA of the mapped file. */
+	u64 consume_va;	/* User VA of the mapped file. */
+};
+
+/* vmci queuepair detach info */
+struct vmci_qp_dtch_info {
+	struct vmci_handle handle;
+	s32 result;
+	u32 _pad;
+};
+
+/*
+ * struct vmci_qp_page_store describes how the memory of a given queue pair
+ * is backed. When the queue pair is between the host and a guest, the
+ * page store consists of references to the guest pages. On vmkernel,
+ * this is a list of PPNs, and on hosted, it is a user VA where the
+ * queue pair is mapped into the VMX address space.
+ */
+struct vmci_qp_page_store {
+	/* Reference to pages backing the queue pair. */
+	u64 pages;
+	/* Length of pageList/virtual addres range (in pages). */
+	u32 len;
+};
+
+/*
+ * This data type contains the information about a queue.
+ * There are two queues (hence, queue pairs) per transaction model between a
+ * pair of end points, A & B.  One queue is used by end point A to transmit
+ * commands and responses to B.  The other queue is used by B to transmit
+ * commands and responses.
+ *
+ * struct vmci_queue_kern_if is a per-OS defined Queue structure.  It contains
+ * either a direct pointer to the linear address of the buffer contents or a
+ * pointer to structures which help the OS locate those data pages.  See
+ * vmciKernelIf.c for each platform for its definition.
+ */
+struct vmci_queue {
+	struct vmci_queue_header *q_header;
+	struct vmci_queue_header *saved_header;
+	struct vmci_queue_kern_if *kernel_if;
+};
+
+/*
+ * Utility function that checks whether the fields of the page
+ * store contain valid values.
+ * Result:
+ * true if the page store is wellformed. false otherwise.
+ */
+static inline bool
+VMCI_QP_PAGESTORE_IS_WELLFORMED(struct vmci_qp_page_store *page_store)
+{
+	return page_store->len >= 2;
+}
+
+void vmci_qp_broker_exit(void);
+int vmci_qp_broker_alloc(struct vmci_handle handle, u32 peer,
+			 u32 flags, u32 priv_flags,
+			 u64 produce_size, u64 consume_size,
+			 struct vmci_qp_page_store *page_store,
+			 struct vmci_ctx *context);
+int vmci_qp_broker_set_page_store(struct vmci_handle handle,
+				  u64 produce_uva, u64 consume_uva,
+				  struct vmci_ctx *context);
+int vmci_qp_broker_detach(struct vmci_handle handle, struct vmci_ctx *context);
+
+void vmci_qp_guest_endpoints_exit(void);
+
+int vmci_qp_alloc(struct vmci_handle *handle,
+		  struct vmci_queue **produce_q, u64 produce_size,
+		  struct vmci_queue **consume_q, u64 consume_size,
+		  u32 peer, u32 flags, u32 priv_flags,
+		  bool guest_endpoint, vmci_event_release_cb wakeup_cb,
+		  void *client_data);
+int vmci_qp_broker_map(struct vmci_handle handle,
+		       struct vmci_ctx *context, u64 guest_mem);
+int vmci_qp_broker_unmap(struct vmci_handle handle,
+			 struct vmci_ctx *context, u32 gid);
+
+#endif /* _VMCI_QUEUE_PAIR_H_ */
diff --git a/drivers/misc/vmw_vmci/vmci_resource.c b/drivers/misc/vmw_vmci/vmci_resource.c
new file mode 100644
index 000000000..da1ee2e1b
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_resource.c
@@ -0,0 +1,229 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/hash.h>
+#include <linux/types.h>
+#include <linux/rculist.h>
+#include <linux/completion.h>
+
+#include "vmci_resource.h"
+#include "vmci_driver.h"
+
+
+#define VMCI_RESOURCE_HASH_BITS         7
+#define VMCI_RESOURCE_HASH_BUCKETS      (1 << VMCI_RESOURCE_HASH_BITS)
+
+struct vmci_hash_table {
+	spinlock_t lock;
+	struct hlist_head entries[VMCI_RESOURCE_HASH_BUCKETS];
+};
+
+static struct vmci_hash_table vmci_resource_table = {
+	.lock = __SPIN_LOCK_UNLOCKED(vmci_resource_table.lock),
+};
+
+static unsigned int vmci_resource_hash(struct vmci_handle handle)
+{
+	return hash_32(handle.resource, VMCI_RESOURCE_HASH_BITS);
+}
+
+/*
+ * Gets a resource (if one exists) matching given handle from the hash table.
+ */
+static struct vmci_resource *vmci_resource_lookup(struct vmci_handle handle,
+						  enum vmci_resource_type type)
+{
+	struct vmci_resource *r, *resource = NULL;
+	unsigned int idx = vmci_resource_hash(handle);
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(r,
+				 &vmci_resource_table.entries[idx], node) {
+		u32 cid = r->handle.context;
+		u32 rid = r->handle.resource;
+
+		if (r->type == type &&
+		    rid == handle.resource &&
+		    (cid == handle.context || cid == VMCI_INVALID_ID ||
+		     handle.context == VMCI_INVALID_ID)) {
+			resource = r;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	return resource;
+}
+
+/*
+ * Find an unused resource ID and return it. The first
+ * VMCI_RESERVED_RESOURCE_ID_MAX are reserved so we start from
+ * its value + 1.
+ * Returns VMCI resource id on success, VMCI_INVALID_ID on failure.
+ */
+static u32 vmci_resource_find_id(u32 context_id,
+				 enum vmci_resource_type resource_type)
+{
+	static u32 resource_id = VMCI_RESERVED_RESOURCE_ID_MAX + 1;
+	u32 old_rid = resource_id;
+	u32 current_rid;
+
+	/*
+	 * Generate a unique resource ID.  Keep on trying until we wrap around
+	 * in the RID space.
+	 */
+	do {
+		struct vmci_handle handle;
+
+		current_rid = resource_id;
+		resource_id++;
+		if (unlikely(resource_id == VMCI_INVALID_ID)) {
+			/* Skip the reserved rids. */
+			resource_id = VMCI_RESERVED_RESOURCE_ID_MAX + 1;
+		}
+
+		handle = vmci_make_handle(context_id, current_rid);
+		if (!vmci_resource_lookup(handle, resource_type))
+			return current_rid;
+	} while (resource_id != old_rid);
+
+	return VMCI_INVALID_ID;
+}
+
+
+int vmci_resource_add(struct vmci_resource *resource,
+		      enum vmci_resource_type resource_type,
+		      struct vmci_handle handle)
+
+{
+	unsigned int idx;
+	int result;
+
+	spin_lock(&vmci_resource_table.lock);
+
+	if (handle.resource == VMCI_INVALID_ID) {
+		handle.resource = vmci_resource_find_id(handle.context,
+			resource_type);
+		if (handle.resource == VMCI_INVALID_ID) {
+			result = VMCI_ERROR_NO_HANDLE;
+			goto out;
+		}
+	} else if (vmci_resource_lookup(handle, resource_type)) {
+		result = VMCI_ERROR_ALREADY_EXISTS;
+		goto out;
+	}
+
+	resource->handle = handle;
+	resource->type = resource_type;
+	INIT_HLIST_NODE(&resource->node);
+	kref_init(&resource->kref);
+	init_completion(&resource->done);
+
+	idx = vmci_resource_hash(resource->handle);
+	hlist_add_head_rcu(&resource->node, &vmci_resource_table.entries[idx]);
+
+	result = VMCI_SUCCESS;
+
+out:
+	spin_unlock(&vmci_resource_table.lock);
+	return result;
+}
+
+void vmci_resource_remove(struct vmci_resource *resource)
+{
+	struct vmci_handle handle = resource->handle;
+	unsigned int idx = vmci_resource_hash(handle);
+	struct vmci_resource *r;
+
+	/* Remove resource from hash table. */
+	spin_lock(&vmci_resource_table.lock);
+
+	hlist_for_each_entry(r, &vmci_resource_table.entries[idx], node) {
+		if (vmci_handle_is_equal(r->handle, resource->handle)) {
+			hlist_del_init_rcu(&r->node);
+			break;
+		}
+	}
+
+	spin_unlock(&vmci_resource_table.lock);
+	synchronize_rcu();
+
+	vmci_resource_put(resource);
+	wait_for_completion(&resource->done);
+}
+
+struct vmci_resource *
+vmci_resource_by_handle(struct vmci_handle resource_handle,
+			enum vmci_resource_type resource_type)
+{
+	struct vmci_resource *r, *resource = NULL;
+
+	rcu_read_lock();
+
+	r = vmci_resource_lookup(resource_handle, resource_type);
+	if (r &&
+	    (resource_type == r->type ||
+	     resource_type == VMCI_RESOURCE_TYPE_ANY)) {
+		resource = vmci_resource_get(r);
+	}
+
+	rcu_read_unlock();
+
+	return resource;
+}
+
+/*
+ * Get a reference to given resource.
+ */
+struct vmci_resource *vmci_resource_get(struct vmci_resource *resource)
+{
+	kref_get(&resource->kref);
+
+	return resource;
+}
+
+static void vmci_release_resource(struct kref *kref)
+{
+	struct vmci_resource *resource =
+		container_of(kref, struct vmci_resource, kref);
+
+	/* Verify the resource has been unlinked from hash table */
+	WARN_ON(!hlist_unhashed(&resource->node));
+
+	/* Signal that container of this resource can now be destroyed */
+	complete(&resource->done);
+}
+
+/*
+ * Resource's release function will get called if last reference.
+ * If it is the last reference, then we are sure that nobody else
+ * can increment the count again (it's gone from the resource hash
+ * table), so there's no need for locking here.
+ */
+int vmci_resource_put(struct vmci_resource *resource)
+{
+	/*
+	 * We propagate the information back to caller in case it wants to know
+	 * whether entry was freed.
+	 */
+	return kref_put(&resource->kref, vmci_release_resource) ?
+		VMCI_SUCCESS_ENTRY_DEAD : VMCI_SUCCESS;
+}
+
+struct vmci_handle vmci_resource_handle(struct vmci_resource *resource)
+{
+	return resource->handle;
+}
diff --git a/drivers/misc/vmw_vmci/vmci_resource.h b/drivers/misc/vmw_vmci/vmci_resource.h
new file mode 100644
index 000000000..9190cd298
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_resource.h
@@ -0,0 +1,59 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#ifndef _VMCI_RESOURCE_H_
+#define _VMCI_RESOURCE_H_
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/types.h>
+
+#include "vmci_context.h"
+
+
+enum vmci_resource_type {
+	VMCI_RESOURCE_TYPE_ANY,
+	VMCI_RESOURCE_TYPE_API,
+	VMCI_RESOURCE_TYPE_GROUP,
+	VMCI_RESOURCE_TYPE_DATAGRAM,
+	VMCI_RESOURCE_TYPE_DOORBELL,
+	VMCI_RESOURCE_TYPE_QPAIR_GUEST,
+	VMCI_RESOURCE_TYPE_QPAIR_HOST
+};
+
+struct vmci_resource {
+	struct vmci_handle handle;
+	enum vmci_resource_type type;
+	struct hlist_node node;
+	struct kref kref;
+	struct completion done;
+};
+
+
+int vmci_resource_add(struct vmci_resource *resource,
+		      enum vmci_resource_type resource_type,
+		      struct vmci_handle handle);
+
+void vmci_resource_remove(struct vmci_resource *resource);
+
+struct vmci_resource *
+vmci_resource_by_handle(struct vmci_handle resource_handle,
+			enum vmci_resource_type resource_type);
+
+struct vmci_resource *vmci_resource_get(struct vmci_resource *resource);
+int vmci_resource_put(struct vmci_resource *resource);
+
+struct vmci_handle vmci_resource_handle(struct vmci_resource *resource);
+
+#endif /* _VMCI_RESOURCE_H_ */
diff --git a/drivers/misc/vmw_vmci/vmci_route.c b/drivers/misc/vmw_vmci/vmci_route.c
new file mode 100644
index 000000000..91090658b
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_route.c
@@ -0,0 +1,226 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+
+#include "vmci_context.h"
+#include "vmci_driver.h"
+#include "vmci_route.h"
+
+/*
+ * Make a routing decision for the given source and destination handles.
+ * This will try to determine the route using the handles and the available
+ * devices.  Will set the source context if it is invalid.
+ */
+int vmci_route(struct vmci_handle *src,
+	       const struct vmci_handle *dst,
+	       bool from_guest,
+	       enum vmci_route *route)
+{
+	bool has_host_device = vmci_host_code_active();
+	bool has_guest_device = vmci_guest_code_active();
+
+	*route = VMCI_ROUTE_NONE;
+
+	/*
+	 * "from_guest" is only ever set to true by
+	 * IOCTL_VMCI_DATAGRAM_SEND (or by the vmkernel equivalent),
+	 * which comes from the VMX, so we know it is coming from a
+	 * guest.
+	 *
+	 * To avoid inconsistencies, test these once.  We will test
+	 * them again when we do the actual send to ensure that we do
+	 * not touch a non-existent device.
+	 */
+
+	/* Must have a valid destination context. */
+	if (VMCI_INVALID_ID == dst->context)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	/* Anywhere to hypervisor. */
+	if (VMCI_HYPERVISOR_CONTEXT_ID == dst->context) {
+
+		/*
+		 * If this message already came from a guest then we
+		 * cannot send it to the hypervisor.  It must come
+		 * from a local client.
+		 */
+		if (from_guest)
+			return VMCI_ERROR_DST_UNREACHABLE;
+
+		/*
+		 * We must be acting as a guest in order to send to
+		 * the hypervisor.
+		 */
+		if (!has_guest_device)
+			return VMCI_ERROR_DEVICE_NOT_FOUND;
+
+		/* And we cannot send if the source is the host context. */
+		if (VMCI_HOST_CONTEXT_ID == src->context)
+			return VMCI_ERROR_INVALID_ARGS;
+
+		/*
+		 * If the client passed the ANON source handle then
+		 * respect it (both context and resource are invalid).
+		 * However, if they passed only an invalid context,
+		 * then they probably mean ANY, in which case we
+		 * should set the real context here before passing it
+		 * down.
+		 */
+		if (VMCI_INVALID_ID == src->context &&
+		    VMCI_INVALID_ID != src->resource)
+			src->context = vmci_get_context_id();
+
+		/* Send from local client down to the hypervisor. */
+		*route = VMCI_ROUTE_AS_GUEST;
+		return VMCI_SUCCESS;
+	}
+
+	/* Anywhere to local client on host. */
+	if (VMCI_HOST_CONTEXT_ID == dst->context) {
+		/*
+		 * If it is not from a guest but we are acting as a
+		 * guest, then we need to send it down to the host.
+		 * Note that if we are also acting as a host then this
+		 * will prevent us from sending from local client to
+		 * local client, but we accept that restriction as a
+		 * way to remove any ambiguity from the host context.
+		 */
+		if (src->context == VMCI_HYPERVISOR_CONTEXT_ID) {
+			/*
+			 * If the hypervisor is the source, this is
+			 * host local communication. The hypervisor
+			 * may send vmci event datagrams to the host
+			 * itself, but it will never send datagrams to
+			 * an "outer host" through the guest device.
+			 */
+
+			if (has_host_device) {
+				*route = VMCI_ROUTE_AS_HOST;
+				return VMCI_SUCCESS;
+			} else {
+				return VMCI_ERROR_DEVICE_NOT_FOUND;
+			}
+		}
+
+		if (!from_guest && has_guest_device) {
+			/* If no source context then use the current. */
+			if (VMCI_INVALID_ID == src->context)
+				src->context = vmci_get_context_id();
+
+			/* Send it from local client down to the host. */
+			*route = VMCI_ROUTE_AS_GUEST;
+			return VMCI_SUCCESS;
+		}
+
+		/*
+		 * Otherwise we already received it from a guest and
+		 * it is destined for a local client on this host, or
+		 * it is from another local client on this host.  We
+		 * must be acting as a host to service it.
+		 */
+		if (!has_host_device)
+			return VMCI_ERROR_DEVICE_NOT_FOUND;
+
+		if (VMCI_INVALID_ID == src->context) {
+			/*
+			 * If it came from a guest then it must have a
+			 * valid context.  Otherwise we can use the
+			 * host context.
+			 */
+			if (from_guest)
+				return VMCI_ERROR_INVALID_ARGS;
+
+			src->context = VMCI_HOST_CONTEXT_ID;
+		}
+
+		/* Route to local client. */
+		*route = VMCI_ROUTE_AS_HOST;
+		return VMCI_SUCCESS;
+	}
+
+	/*
+	 * If we are acting as a host then this might be destined for
+	 * a guest.
+	 */
+	if (has_host_device) {
+		/* It will have a context if it is meant for a guest. */
+		if (vmci_ctx_exists(dst->context)) {
+			if (VMCI_INVALID_ID == src->context) {
+				/*
+				 * If it came from a guest then it
+				 * must have a valid context.
+				 * Otherwise we can use the host
+				 * context.
+				 */
+
+				if (from_guest)
+					return VMCI_ERROR_INVALID_ARGS;
+
+				src->context = VMCI_HOST_CONTEXT_ID;
+			} else if (VMCI_CONTEXT_IS_VM(src->context) &&
+				   src->context != dst->context) {
+				/*
+				 * VM to VM communication is not
+				 * allowed. Since we catch all
+				 * communication destined for the host
+				 * above, this must be destined for a
+				 * VM since there is a valid context.
+				 */
+
+				return VMCI_ERROR_DST_UNREACHABLE;
+			}
+
+			/* Pass it up to the guest. */
+			*route = VMCI_ROUTE_AS_HOST;
+			return VMCI_SUCCESS;
+		} else if (!has_guest_device) {
+			/*
+			 * The host is attempting to reach a CID
+			 * without an active context, and we can't
+			 * send it down, since we have no guest
+			 * device.
+			 */
+
+			return VMCI_ERROR_DST_UNREACHABLE;
+		}
+	}
+
+	/*
+	 * We must be a guest trying to send to another guest, which means
+	 * we need to send it down to the host. We do not filter out VM to
+	 * VM communication here, since we want to be able to use the guest
+	 * driver on older versions that do support VM to VM communication.
+	 */
+	if (!has_guest_device) {
+		/*
+		 * Ending up here means we have neither guest nor host
+		 * device.
+		 */
+		return VMCI_ERROR_DEVICE_NOT_FOUND;
+	}
+
+	/* If no source context then use the current context. */
+	if (VMCI_INVALID_ID == src->context)
+		src->context = vmci_get_context_id();
+
+	/*
+	 * Send it from local client down to the host, which will
+	 * route it to the other guest for us.
+	 */
+	*route = VMCI_ROUTE_AS_GUEST;
+	return VMCI_SUCCESS;
+}
diff --git a/drivers/misc/vmw_vmci/vmci_route.h b/drivers/misc/vmw_vmci/vmci_route.h
new file mode 100644
index 000000000..3b30e8241
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_route.h
@@ -0,0 +1,30 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#ifndef _VMCI_ROUTE_H_
+#define _VMCI_ROUTE_H_
+
+#include <linux/vmw_vmci_defs.h>
+
+enum vmci_route {
+	VMCI_ROUTE_NONE,
+	VMCI_ROUTE_AS_HOST,
+	VMCI_ROUTE_AS_GUEST,
+};
+
+int vmci_route(struct vmci_handle *src, const struct vmci_handle *dst,
+	       bool from_guest, enum vmci_route *route);
+
+#endif /* _VMCI_ROUTE_H_ */