[vmw_vmci RFC 01/11] Apply VMCI context code

["Andrew Stiegmann (stieg)" <astiegmann@vmware.com>]

Context code maintains state for vmci and allows the driver
to communicate with multiple VMs.

Signed-off-by: Andrew Stiegmann (stieg) <astiegmann@vmware.com>
---
 drivers/misc/vmw_vmci/vmci_context.c | 1743 ++++++++++++++++++++++++++++++++++
 drivers/misc/vmw_vmci/vmci_context.h |  150 +++
 2 files changed, 1893 insertions(+), 0 deletions(-)
 create mode 100644 drivers/misc/vmw_vmci/vmci_context.c
 create mode 100644 drivers/misc/vmw_vmci/vmci_context.h

diff --git a/drivers/misc/vmw_vmci/vmci_context.c b/drivers/misc/vmw_vmci/vmci_context.c
new file mode 100644
index 0000000..16b10b9
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_context.c
@@ -0,0 +1,1743 @@
+/*
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include <linux/highmem.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/vmw_vmci_api.h>
+#include <linux/vmw_vmci_defs.h>
+
+#include "vmci_common_int.h"
+#include "vmci_context.h"
+#include "vmci_datagram.h"
+#include "vmci_doorbell.h"
+#include "vmci_driver.h"
+#include "vmci_event.h"
+#include "vmci_queue_pair.h"
+
+/* List of current VMCI contexts. */
+static struct {
+	struct list_head head;
+	spinlock_t lock;
+	spinlock_t firingLock;
+} ctx_list;
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ctx_signal_notify --
+ *
+ *      Sets the notify flag to true.  Assumes that the context lock is
+ *      held.
+ *
+ * Results:
+ *      None.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void ctx_signal_notify(struct vmci_ctx *context)
+{
+	if (context->notify)
+		*context->notify = true;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ctx_clear_notify --
+ *
+ *      Sets the notify flag to false.  Assumes that the context lock is
+ *      held.
+ *
+ * Results:
+ *      None.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void ctx_clear_notify(struct vmci_ctx *context)
+{
+	if (context->notify)
+		*context->notify = false;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ctx_clear_notify_call --
+ *
+ *      If nothing requires the attention of the guest, clears both
+ *      notify flag and call.
+ *
+ * Results:
+ *      None.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void ctx_clear_notify_call(struct vmci_ctx *context)
+{
+	if (context->pendingDatagrams == 0 &&
+	    vmci_handle_arr_get_size(context->pendingDoorbellArray) == 0)
+		ctx_clear_notify(context);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_check_signal_notify --
+ *
+ *      Sets the context's notify flag iff datagrams are pending for this
+ *      context.  Called from vmci_setup_notify().
+ *
+ * Results:
+ *      None.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void vmci_ctx_check_signal_notify(struct vmci_ctx *context)
+{
+	ASSERT(context);
+
+	spin_lock(&ctx_list.lock);
+	if (context->pendingDatagrams)
+		ctx_signal_notify(context);
+	spin_unlock(&ctx_list.lock);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_init --
+ *
+ *      Initializes the VMCI context module.
+ *
+ * Results:
+ *      None.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int __init vmci_ctx_init(void)
+{
+	INIT_LIST_HEAD(&ctx_list.head);
+
+	spin_lock_init(&ctx_list.lock);
+	spin_lock_init(&ctx_list.firingLock);
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ctx_exists_locked --
+ *
+ *      Internal helper to check if a context with the specified context
+ *      ID exists. Assumes the ctx_list.lock is held.
+ *
+ * Results:
+ *      true if a context exists with the given cid.
+ *      false otherwise
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static bool ctx_exists_locked(uint32_t cid)	// IN
+{
+	struct vmci_ctx *context;
+
+	list_for_each_entry(context, &ctx_list.head, listItem) {
+		if (context->cid == cid)
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_init_ctx --
+ *
+ *      Allocates and initializes a VMCI context.
+ *
+ * Results:
+ *      Returns 0 on success, appropriate error code otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_init_ctx(uint32_t cid,
+		      uint32_t privFlags,
+		      uintptr_t eventHnd,
+		      int userVersion,
+		      uid_t * user, struct vmci_ctx **outContext)
+{
+	struct vmci_ctx *context;
+	int result;
+
+	if (privFlags & ~VMCI_PRIVILEGE_ALL_FLAGS) {
+		pr_devel("Invalid flag (flags=0x%x) for VMCI context.",
+			 privFlags);
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	if (userVersion == 0)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	context = kzalloc(sizeof *context, GFP_KERNEL);
+	if (context == NULL) {
+		pr_warn("Failed to allocate memory for VMCI context.");
+		return VMCI_ERROR_NO_MEM;
+	}
+
+	INIT_LIST_HEAD(&context->listItem);
+	INIT_LIST_HEAD(&context->datagramQueue);
+
+	context->userVersion = userVersion;
+
+	context->queuePairArray = vmci_handle_arr_create(0);
+	if (!context->queuePairArray) {
+		result = VMCI_ERROR_NO_MEM;
+		goto error;
+	}
+
+	context->doorbellArray = vmci_handle_arr_create(0);
+	if (!context->doorbellArray) {
+		result = VMCI_ERROR_NO_MEM;
+		goto error;
+	}
+
+	context->pendingDoorbellArray = vmci_handle_arr_create(0);
+	if (!context->pendingDoorbellArray) {
+		result = VMCI_ERROR_NO_MEM;
+		goto error;
+	}
+
+	context->notifierArray = vmci_handle_arr_create(0);
+	if (context->notifierArray == NULL) {
+		result = VMCI_ERROR_NO_MEM;
+		goto error;
+	}
+
+	spin_lock_init(&context->lock);
+
+	atomic_set(&context->refCount, 1);
+
+	/* Inititialize host-specific VMCI context. */
+	init_waitqueue_head(&context->hostContext.waitQueue);
+
+	context->privFlags = privFlags;
+
+	/*
+	 * 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);
+	ASSERT(cid != VMCI_INVALID_ID);
+	while (ctx_exists_locked(cid)) {
+
+		/*
+		 * If the cid is below our limit and we collide we are creating duplicate
+		 * contexts internally so we want to assert fail in that case.
+		 */
+		ASSERT(cid >= VMCI_RESERVED_CID_LIMIT);
+
+		/* 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;
+	}
+	ASSERT(!ctx_exists_locked(cid));
+	context->cid = cid;
+	context->validUser = user != NULL;
+	if (context->validUser)
+		context->user = *user;
+	list_add(&context->listItem, &ctx_list.head);
+	spin_unlock(&ctx_list.lock);
+
+	context->notify = NULL;
+	context->notifyPage = NULL;
+
+	*outContext = context;
+	return VMCI_SUCCESS;
+
+error:
+	if (context->notifierArray)
+		vmci_handle_arr_destroy(context->notifierArray);
+	if (context->queuePairArray)
+		vmci_handle_arr_destroy(context->queuePairArray);
+	if (context->doorbellArray)
+		vmci_handle_arr_destroy(context->doorbellArray);
+	if (context->pendingDoorbellArray)
+		vmci_handle_arr_destroy(context->pendingDoorbellArray);
+	kfree(context);
+	return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_release_ctx --
+ *
+ *      Cleans up a VMCI context.
+ *
+ * Results:
+ *      None.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void vmci_ctx_release_ctx(struct vmci_ctx *context)	// IN
+{
+	/* Dequeue VMCI context. */
+
+	spin_lock(&ctx_list.lock);
+	list_del(&context->listItem);
+	spin_unlock(&ctx_list.lock);
+
+	vmci_ctx_release(context);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ctx_fire_notification --
+ *
+ *      Fire notification for all contexts interested in given cid.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, error code otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int ctx_fire_notification(uint32_t contextID,	// IN
+				 uint32_t privFlags)	// IN
+{
+	uint32_t i, arraySize;
+	struct vmci_ctx *subCtx;
+	struct vmci_handle_arr *subscriberArray;
+	struct vmci_handle contextHandle =
+		vmci_make_handle(contextID, VMCI_EVENT_HANDLER);
+
+	/*
+	 * We create an array to hold the subscribers we find when scanning through
+	 * all contexts.
+	 */
+	subscriberArray = vmci_handle_arr_create(0);
+	if (subscriberArray == NULL)
+		return VMCI_ERROR_NO_MEM;
+
+	/*
+	 * Scan all contexts to find who is interested in being notified about
+	 * given contextID. We have a special firingLock that we use to synchronize
+	 * across all notification operations. This avoids us having to take the
+	 * context lock for each HasEntry call and it solves a lock ranking issue.
+	 */
+	spin_lock(&ctx_list.firingLock);
+	spin_lock(&ctx_list.lock);
+	list_for_each_entry(subCtx, &ctx_list.head, listItem) {
+		/*
+		 * We only deliver notifications of the removal of contexts, if
+		 * the two contexts are allowed to interact.
+		 */
+		if (vmci_handle_arr_has_entry
+		    (subCtx->notifierArray, contextHandle)
+		    && !vmci_deny_interaction(privFlags, subCtx->privFlags)) {
+			vmci_handle_arr_append_entry(&subscriberArray,
+						     vmci_make_handle
+						     (subCtx->cid,
+						      VMCI_EVENT_HANDLER));
+		}
+	}
+	spin_unlock(&ctx_list.lock);
+	spin_unlock(&ctx_list.firingLock);
+
+	/* Fire event to all subscribers. */
+	arraySize = vmci_handle_arr_get_size(subscriberArray);
+	for (i = 0; i < arraySize; i++) {
+		int result;
+		struct vmci_event_msg *eMsg;
+		struct vmci_event_payld_ctx *evPayload;
+		char buf[sizeof *eMsg + sizeof *evPayload];
+
+		eMsg = (struct vmci_event_msg *)buf;
+
+		/* Clear out any garbage. */
+		memset(eMsg, 0, sizeof *eMsg + sizeof *evPayload);
+		eMsg->hdr.dst = vmci_handle_arr_get_entry(subscriberArray, i);
+		eMsg->hdr.src =
+			vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
+					 VMCI_CONTEXT_RESOURCE_ID);
+		eMsg->hdr.payloadSize =
+			sizeof *eMsg + sizeof *evPayload - sizeof eMsg->hdr;
+		eMsg->eventData.event = VMCI_EVENT_CTX_REMOVED;
+		evPayload = vmci_event_data_payload(&eMsg->eventData);
+		evPayload->contextID = contextID;
+
+		result = vmci_dg_dispatch(VMCI_HYPERVISOR_CONTEXT_ID,
+					  (struct vmci_dg *)
+					  eMsg, false);
+		if (result < VMCI_SUCCESS) {
+			pr_devel("Failed to enqueue event datagram "
+				 "(type=%d) for context (ID=0x%x).",
+				 eMsg->eventData.event, eMsg->hdr.dst.context);
+			/* We continue to enqueue on next subscriber. */
+		}
+	}
+	vmci_handle_arr_destroy(subscriberArray);
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ *-----------------------------------------------------------------------------
+ *
+ * ctx_free_ctx --
+ *
+ *      Deallocates all parts of a context datastructure. This
+ *      functions doesn't lock the context, because it assumes that
+ *      the caller is holding the last reference to context.
+ *
+ * Results:
+ *      None.
+ *
+ * Side effects:
+ *      Paged memory is freed.
+ *
+ *-----------------------------------------------------------------------------
+ */
+
+static void ctx_free_ctx(struct vmci_ctx *context)	// IN
+{
+	struct list_head *curr;
+	struct list_head *next;
+	struct vmci_dg_queue_entry *dqEntry;
+	struct vmci_handle tempHandle;
+
+	/* Fire event to all contexts interested in knowing this context is dying. */
+	ctx_fire_notification(context->cid, context->privFlags);
+
+	/*
+	 * 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.
+	 */
+
+	tempHandle = vmci_handle_arr_get_entry(context->queuePairArray, 0);
+	while (!VMCI_HANDLE_EQUAL(tempHandle, VMCI_INVALID_HANDLE)) {
+		if (vmci_qp_broker_detach(tempHandle, 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->queuePairArray,
+						     tempHandle);
+		}
+		tempHandle =
+			vmci_handle_arr_get_entry(context->queuePairArray, 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_safe(curr, next, &context->datagramQueue) {
+		dqEntry =
+			list_entry(curr, struct vmci_dg_queue_entry, listItem);
+		list_del(curr);
+		ASSERT(dqEntry && dqEntry->dg);
+		ASSERT(dqEntry->dgSize == VMCI_DG_SIZE(dqEntry->dg));
+		kfree(dqEntry->dg);
+		kfree(dqEntry);
+	}
+
+	vmci_handle_arr_destroy(context->notifierArray);
+	vmci_handle_arr_destroy(context->queuePairArray);
+	vmci_handle_arr_destroy(context->doorbellArray);
+	vmci_handle_arr_destroy(context->pendingDoorbellArray);
+	vmci_ctx_unset_notify(context);
+	kfree(context);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_pending_dgs --
+ *
+ *      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.
+ *
+ * Results:
+ *      Length of datagram queue for the given context.
+ *
+ * Side effects:
+ *      Locks datagram queue.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_pending_dgs(uint32_t cid,	// IN
+			 uint32_t * pending)	// OUT
+{
+	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->pendingDatagrams;
+	spin_unlock(&context->lock);
+	vmci_ctx_release(context);
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_enqueue_dg --
+ *
+ *      Queues a VMCI datagram for the appropriate target VM
+ *      context.
+ *
+ * Results:
+ *      Size of enqueued data on success, appropriate error code otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_enqueue_dg(uint32_t cid,	// IN: Target VM
+			struct vmci_dg *dg)	// IN:
+{
+	struct vmci_dg_queue_entry *dqEntry;
+	struct vmci_ctx *context;
+	struct vmci_handle dgSrc;
+	size_t vmciDgSize;
+
+	ASSERT(dg);
+	vmciDgSize = VMCI_DG_SIZE(dg);
+	ASSERT(vmciDgSize <= VMCI_MAX_DG_SIZE);
+
+	/* Get the target VM's VMCI context. */
+	context = vmci_ctx_get(cid);
+	if (context == NULL) {
+		pr_devel("Invalid context (ID=0x%x).", cid);
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	/* Allocate guest call entry and add it to the target VM's queue. */
+	dqEntry = kmalloc(sizeof *dqEntry, GFP_KERNEL);
+	if (dqEntry == NULL) {
+		pr_warn("Failed to allocate memory for datagram.");
+		vmci_ctx_release(context);
+		return VMCI_ERROR_NO_MEM;
+	}
+	dqEntry->dg = dg;
+	dqEntry->dgSize = vmciDgSize;
+	dgSrc = dg->src;
+	INIT_LIST_HEAD(&dqEntry->listItem);
+
+	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->datagramQueueSize + vmciDgSize >=
+	    VMCI_MAX_DATAGRAM_QUEUE_SIZE &&
+	    (!VMCI_HANDLE_EQUAL(dgSrc,
+				vmci_make_handle
+				(VMCI_HYPERVISOR_CONTEXT_ID,
+				 VMCI_CONTEXT_RESOURCE_ID))
+	     || context->datagramQueueSize + vmciDgSize >=
+	     VMCI_MAX_DATAGRAM_AND_EVENT_QUEUE_SIZE)) {
+		spin_unlock(&context->lock);
+		vmci_ctx_release(context);
+		kfree(dqEntry);
+		pr_devel("Context (ID=0x%x) receive queue is full.",
+			 cid);
+		return VMCI_ERROR_NO_RESOURCES;
+	}
+
+	list_add(&dqEntry->listItem, &context->datagramQueue);
+	context->pendingDatagrams++;
+	context->datagramQueueSize += vmciDgSize;
+	ctx_signal_notify(context);
+	wake_up(&context->hostContext.waitQueue);
+	spin_unlock(&context->lock);
+	vmci_ctx_release(context);
+
+	return vmciDgSize;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_exists --
+ *
+ *      Verifies whether a context with the specified context ID exists.
+ *
+ * Results:
+ *      true if a context exists with the given cid.
+ *      false otherwise
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+bool vmci_ctx_exists(uint32_t cid)	// IN
+{
+	bool rv;
+
+	spin_lock(&ctx_list.lock);
+	rv = ctx_exists_locked(cid);
+	spin_unlock(&ctx_list.lock);
+	return rv;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_get --
+ *
+ *      Retrieves VMCI context corresponding to the given cid.
+ *
+ * Results:
+ *      VMCI context on success, NULL otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+struct vmci_ctx *vmci_ctx_get(uint32_t cid)	// IN
+{
+	struct vmci_ctx *context = NULL;
+
+	if (cid == VMCI_INVALID_ID)
+		return NULL;
+
+	spin_lock(&ctx_list.lock);
+	list_for_each_entry(context, &ctx_list.head, listItem) {
+		if (context->cid == cid) {
+			/*
+			 * At this point, we are sure that the reference count is
+			 * larger already than zero. When starting the destruction of
+			 * a context, we always remove it from the context list
+			 * before decreasing the reference count. As we found the
+			 * context here, it hasn't been destroyed yet. This means
+			 * that we are not about to increase the reference count of
+			 * something that is in the process of being destroyed.
+			 */
+
+			atomic_inc(&context->refCount);
+			break;
+		}
+	}
+	spin_unlock(&ctx_list.lock);
+
+	return (context && context->cid == cid) ? context : NULL;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_release --
+ *
+ *      Releases the 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). This function musn't be called with a
+ *      lock held.
+ *
+ * Results:
+ *      None.
+ *
+ * Side effects:
+ *      Paged memory may be deallocated.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void vmci_ctx_release(struct vmci_ctx *context)	// IN
+{
+	ASSERT(context);
+	if (atomic_dec_and_test(&context->refCount))
+		ctx_free_ctx(context);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_dequeue_dg --
+ *
+ *      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 maxSize. If larger maxSize is set to
+ *      the size of the datagram to give the caller a chance to
+ *      set up a larger buffer for the guestcall.
+ *
+ * Results:
+ *      On success:  0 if no more pending datagrams, otherwise the size of
+ *                   the next pending datagram.
+ *      On failure:  appropriate error code.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_dequeue_dg(struct vmci_ctx *context,	// IN
+			size_t * maxSize,	// IN/OUT: max size of
+			//         datagram caller can handle.
+			struct vmci_dg **dg)	// OUT:
+{
+	struct vmci_dg_queue_entry *dqEntry;
+	struct list_head *listItem;
+	int rv;
+
+	ASSERT(context && dg);
+
+	/* Dequeue the next datagram entry. */
+	spin_lock(&context->lock);
+	if (context->pendingDatagrams == 0) {
+		ctx_clear_notify_call(context);
+		spin_unlock(&context->lock);
+		pr_devel("No datagrams pending.");
+		return VMCI_ERROR_NO_MORE_DATAGRAMS;
+	}
+
+	listItem = context->datagramQueue.next;
+	ASSERT(!list_empty(&context->datagramQueue));
+
+	dqEntry = list_entry(listItem, struct vmci_dg_queue_entry, listItem);
+	ASSERT(dqEntry->dg);
+
+	/* Check size of caller's buffer. */
+	if (*maxSize < dqEntry->dgSize) {
+		*maxSize = dqEntry->dgSize;
+		spin_unlock(&context->lock);
+		pr_devel("Caller's buffer should be at least "
+			 "(size=%u bytes).", (uint32_t) * maxSize);
+		return VMCI_ERROR_NO_MEM;
+	}
+
+	list_del(listItem);
+	context->pendingDatagrams--;
+	context->datagramQueueSize -= dqEntry->dgSize;
+	if (context->pendingDatagrams == 0) {
+		ctx_clear_notify_call(context);
+		rv = VMCI_SUCCESS;
+	} else {
+		/*
+		 * Return the size of the next datagram.
+		 */
+		struct vmci_dg_queue_entry *nextEntry;
+
+		listItem = context->datagramQueue.next;
+		ASSERT(!list_empty(&context->datagramQueue));
+		nextEntry =
+			list_entry(listItem, struct vmci_dg_queue_entry, listItem);
+		ASSERT(nextEntry && nextEntry->dg);
+		/*
+		 * The following size_t -> int truncation is fine as the maximum size of
+		 * a (routable) datagram is 68KB.
+		 */
+		rv = (int)nextEntry->dgSize;
+	}
+	spin_unlock(&context->lock);
+
+	/* Caller must free datagram. */
+	ASSERT(dqEntry->dgSize == VMCI_DG_SIZE(dqEntry->dg));
+	*dg = dqEntry->dg;
+	dqEntry->dg = NULL;
+	kfree(dqEntry);
+
+	return rv;
+}
+
+/*
+ *-----------------------------------------------------------------------------
+ *
+ * vmci_ctx_unset_notify --
+ *
+ *      Reverts actions set up by vmci_setup_notify().  Unmaps and unlocks the
+ *      page mapped/locked by vmci_setup_notify().
+ *
+ * Results:
+ *      None.
+ *
+ * Side effects:
+ *      None.
+ *
+ *-----------------------------------------------------------------------------
+ */
+
+void vmci_ctx_unset_notify(struct vmci_ctx *context)
+{
+	struct page *notifyPage = context->notifyPage;
+
+	if (!notifyPage)
+		return;
+
+	context->notify = NULL;
+	context->notifyPage = NULL;
+	kunmap(notifyPage);
+	put_page(notifyPage);
+
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_get_id --
+ *
+ *      Retrieves context id of given VMCI context.
+ *
+ * Results:
+ *      uint32_t of context on success, VMCI_INVALID_ID otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+uint32_t vmci_ctx_get_id(struct vmci_ctx * context)	// IN:
+{
+	if (!context)
+		return VMCI_INVALID_ID;
+
+	ASSERT(context->cid != VMCI_INVALID_ID);
+	return context->cid;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * VMCIContext_GetPrivFlags --
+ *
+ *      Retrieves the privilege flags of the given VMCI context ID.
+ *
+ * Results:
+ *     Context's privilege flags.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+uint32_t VMCIContext_GetPrivFlags(uint32_t contextID)	// IN
+{
+	if (vmci_host_code_active()) {
+		uint32_t flags;
+		struct vmci_ctx *context;
+
+		context = vmci_ctx_get(contextID);
+		if (!context)
+			return VMCI_LEAST_PRIVILEGE_FLAGS;
+
+		flags = context->privFlags;
+		vmci_ctx_release(context);
+		return flags;
+	}
+	return VMCI_NO_PRIVILEGE_FLAGS;
+}
+
+EXPORT_SYMBOL(VMCIContext_GetPrivFlags);
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_add_notification --
+ *
+ *      Add remoteCID to list of contexts current contexts wants
+ *      notifications from/about.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, error code otherwise.
+ *
+ * Side effects:
+ *      As in vmci_handle_arr_append_entry().
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_add_notification(uint32_t contextID,	// IN:
+			      uint32_t remoteCID)	// IN:
+{
+	int result = VMCI_ERROR_ALREADY_EXISTS;
+	struct vmci_handle notifierHandle;
+	struct vmci_ctx *context = vmci_ctx_get(contextID);
+	if (context == NULL)
+		return VMCI_ERROR_NOT_FOUND;
+
+	if (VMCI_CONTEXT_IS_VM(contextID) && VMCI_CONTEXT_IS_VM(remoteCID)) {
+		pr_devel("Context removed notifications for other VMs not "
+			 "supported (src=0x%x, remote=0x%x).",
+			 contextID, remoteCID);
+		result = VMCI_ERROR_DST_UNREACHABLE;
+		goto out;
+	}
+
+	if (context->privFlags & VMCI_PRIVILEGE_FLAG_RESTRICTED) {
+		result = VMCI_ERROR_NO_ACCESS;
+		goto out;
+	}
+
+	notifierHandle = vmci_make_handle(remoteCID, VMCI_EVENT_HANDLER);
+	spin_lock(&ctx_list.firingLock);
+	spin_lock(&context->lock);
+	if (!vmci_handle_arr_has_entry(context->notifierArray, notifierHandle)) {
+		vmci_handle_arr_append_entry(&context->notifierArray,
+					     notifierHandle);
+		result = VMCI_SUCCESS;
+	}
+	spin_unlock(&context->lock);
+	spin_unlock(&ctx_list.firingLock);
+out:
+	vmci_ctx_release(context);
+	return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_remove_notification --
+ *
+ *      Remove remoteCID from current context's list of contexts it is
+ *      interested in getting notifications from/about.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, error code otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_remove_notification(uint32_t contextID,	// IN:
+				 uint32_t remoteCID)	// IN:
+{
+	struct vmci_ctx *context = vmci_ctx_get(contextID);
+	struct vmci_handle tmpHandle;
+	if (context == NULL)
+		return VMCI_ERROR_NOT_FOUND;
+
+	spin_lock(&ctx_list.firingLock);
+	spin_lock(&context->lock);
+	tmpHandle =
+		vmci_handle_arr_remove_entry(context->notifierArray,
+					     vmci_make_handle(remoteCID,
+							      VMCI_EVENT_HANDLER));
+	spin_unlock(&context->lock);
+	spin_unlock(&ctx_list.firingLock);
+	vmci_ctx_release(context);
+
+	if (VMCI_HANDLE_EQUAL(tmpHandle, VMCI_INVALID_HANDLE))
+		return VMCI_ERROR_NOT_FOUND;
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_get_chkpt_state --
+ *
+ *      Get current context's checkpoint state of given type.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, error code otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_get_chkpt_state(uint32_t contextID,	// IN:
+			     uint32_t cptType,	// IN:
+			     uint32_t * bufSize,	// IN/OUT:
+			     char **cptBufPtr)	// OUT:
+{
+	int i, result;
+	uint32_t arraySize, cptDataSize;
+	struct vmci_handle_arr *array;
+	struct vmci_ctx *context;
+	char *cptBuf;
+	bool getContextID;
+
+	ASSERT(bufSize && cptBufPtr);
+
+	context = vmci_ctx_get(contextID);
+	if (context == NULL)
+		return VMCI_ERROR_NOT_FOUND;
+
+	spin_lock(&context->lock);
+	if (cptType == VMCI_NOTIFICATION_CPT_STATE) {
+		ASSERT(context->notifierArray);
+		array = context->notifierArray;
+		getContextID = true;
+	} else if (cptType == VMCI_WELLKNOWN_CPT_STATE) {
+		/*
+		 * For compatibility with VMX'en with VM to VM communication, we
+		 * always return zero wellknown handles.
+		 */
+
+		*bufSize = 0;
+		*cptBufPtr = NULL;
+		result = VMCI_SUCCESS;
+		goto release;
+	} else if (cptType == VMCI_DOORBELL_CPT_STATE) {
+		ASSERT(context->doorbellArray);
+		array = context->doorbellArray;
+		getContextID = false;
+	} else {
+		pr_devel("Invalid cpt state (type=%d).", cptType);
+		result = VMCI_ERROR_INVALID_ARGS;
+		goto release;
+	}
+
+	arraySize = vmci_handle_arr_get_size(array);
+	if (arraySize > 0) {
+		if (cptType == VMCI_DOORBELL_CPT_STATE) {
+			cptDataSize =
+				arraySize * sizeof(struct dbell_cpt_state);
+		} else {
+			cptDataSize = arraySize * sizeof(uint32_t);
+		}
+
+		if (*bufSize < cptDataSize) {
+			*bufSize = cptDataSize;
+			result = VMCI_ERROR_MORE_DATA;
+			goto release;
+		}
+
+		cptBuf = kmalloc(cptDataSize, GFP_ATOMIC);
+
+		if (cptBuf == NULL) {
+			result = VMCI_ERROR_NO_MEM;
+			goto release;
+		}
+
+		for (i = 0; i < arraySize; i++) {
+			struct vmci_handle tmpHandle =
+				vmci_handle_arr_get_entry(array, i);
+			if (cptType == VMCI_DOORBELL_CPT_STATE) {
+				((struct dbell_cpt_state *)cptBuf)[i].handle =
+					tmpHandle;
+			} else {
+				((uint32_t *) cptBuf)[i] =
+					getContextID ? tmpHandle.context :
+					tmpHandle.resource;
+			}
+		}
+		*bufSize = cptDataSize;
+		*cptBufPtr = cptBuf;
+	} else {
+		*bufSize = 0;
+		*cptBufPtr = NULL;
+	}
+	result = VMCI_SUCCESS;
+
+release:
+	spin_unlock(&context->lock);
+	vmci_ctx_release(context);
+
+	return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_set_chkpt_state --
+ *
+ *      Set current context's checkpoint state of given type.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, error code otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_set_chkpt_state(uint32_t contextID,	// IN:
+			     uint32_t cptType,	// IN:
+			     uint32_t bufSize,	// IN:
+			     char *cptBuf)	// IN:
+{
+	uint32_t i;
+	uint32_t currentID;
+	int result = VMCI_SUCCESS;
+	uint32_t numIDs = bufSize / sizeof(uint32_t);
+	ASSERT(cptBuf);
+
+	if (cptType == VMCI_WELLKNOWN_CPT_STATE && numIDs > 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.");
+		return VMCI_ERROR_OBSOLETE;
+	}
+
+	if (cptType != VMCI_NOTIFICATION_CPT_STATE) {
+		pr_devel("Invalid cpt state (type=%d).", cptType);
+		return VMCI_ERROR_INVALID_ARGS;
+	}
+
+	for (i = 0; i < numIDs && result == VMCI_SUCCESS; i++) {
+		currentID = ((uint32_t *) cptBuf)[i];
+		result = vmci_ctx_add_notification(contextID, currentID);
+		if (result != VMCI_SUCCESS)
+			break;
+	}
+	if (result != VMCI_SUCCESS)
+		pr_devel("Failed to set cpt state (type=%d) "
+			 "(error=%d).", cptType, result);
+
+	return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_rcv_notifications_get --
+ *
+ *      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.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, error code otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_rcv_notifications_get(uint32_t contextID,	// IN
+				   struct vmci_handle_arr **dbHandleArray,	// OUT
+				   struct vmci_handle_arr **qpHandleArray)	// OUT
+{
+	struct vmci_ctx *context;
+	int result = VMCI_SUCCESS;
+
+	ASSERT(dbHandleArray && qpHandleArray);
+
+	context = vmci_ctx_get(contextID);
+	if (context == NULL)
+		return VMCI_ERROR_NOT_FOUND;
+
+	spin_lock(&context->lock);
+
+	*dbHandleArray = context->pendingDoorbellArray;
+	context->pendingDoorbellArray = vmci_handle_arr_create(0);
+	if (!context->pendingDoorbellArray) {
+		context->pendingDoorbellArray = *dbHandleArray;
+		*dbHandleArray = NULL;
+		result = VMCI_ERROR_NO_MEM;
+	}
+	*qpHandleArray = NULL;
+
+	spin_unlock(&context->lock);
+	vmci_ctx_release(context);
+
+	return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_rcv_notifications_release --
+ *
+ *      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.
+ *
+ * Results:
+ *      None.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void vmci_ctx_rcv_notifications_release(uint32_t contextID,	// IN
+					struct vmci_handle_arr *dbHandleArray,	// IN
+					struct vmci_handle_arr *qpHandleArray,	// IN
+					bool success)	// IN
+{
+	struct vmci_ctx *context = vmci_ctx_get(contextID);
+
+	if (context) {
+		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->pendingDoorbellArray);
+			while (!VMCI_HANDLE_INVALID(handle)) {
+				ASSERT(vmci_handle_arr_has_entry
+				       (context->doorbellArray, handle));
+				if (!vmci_handle_arr_has_entry
+				    (dbHandleArray, handle)) {
+					vmci_handle_arr_append_entry
+						(&dbHandleArray, handle);
+				}
+				handle = vmci_handle_arr_remove_tail(
+					context->pendingDoorbellArray);
+			}
+			vmci_handle_arr_destroy(context->pendingDoorbellArray);
+			context->pendingDoorbellArray = dbHandleArray;
+			dbHandleArray = NULL;
+		} else {
+			ctx_clear_notify_call(context);
+		}
+		spin_unlock(&context->lock);
+		vmci_ctx_release(context);
+	} else {
+		/*
+		 * The OS driver part is holding on to the context for the
+		 * duration of the receive notification ioctl, so it should
+		 * still be here.
+		 */
+
+		ASSERT(false);
+	}
+
+	if (dbHandleArray)
+		vmci_handle_arr_destroy(dbHandleArray);
+
+	if (qpHandleArray)
+		vmci_handle_arr_destroy(qpHandleArray);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_dbell_create --
+ *
+ *      Registers that a new doorbell handle has been allocated by the
+ *      context. Only doorbell handles registered can be notified.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, appropriate error code otherewise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_dbell_create(uint32_t contextID,	// IN
+			  struct vmci_handle handle)	// IN
+{
+	struct vmci_ctx *context;
+	int result;
+
+	if (contextID == VMCI_INVALID_ID || VMCI_HANDLE_INVALID(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	context = vmci_ctx_get(contextID);
+	if (context == NULL)
+		return VMCI_ERROR_NOT_FOUND;
+
+	spin_lock(&context->lock);
+	if (!vmci_handle_arr_has_entry(context->doorbellArray, handle)) {
+		vmci_handle_arr_append_entry(&context->doorbellArray, handle);
+		result = VMCI_SUCCESS;
+	} else {
+		result = VMCI_ERROR_DUPLICATE_ENTRY;
+	}
+
+	spin_unlock(&context->lock);
+	vmci_ctx_release(context);
+
+	return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_dbell_destroy --
+ *
+ *      Unregisters a doorbell handle that was previously registered
+ *      with vmci_ctx_dbell_create.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, appropriate error code otherewise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_dbell_destroy(uint32_t contextID,	// IN
+			   struct vmci_handle handle)	// IN
+{
+	struct vmci_ctx *context;
+	struct vmci_handle removedHandle;
+
+	if (contextID == VMCI_INVALID_ID || VMCI_HANDLE_INVALID(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	context = vmci_ctx_get(contextID);
+	if (context == NULL)
+		return VMCI_ERROR_NOT_FOUND;
+
+	spin_lock(&context->lock);
+	removedHandle =
+		vmci_handle_arr_remove_entry(context->doorbellArray, handle);
+	vmci_handle_arr_remove_entry(context->pendingDoorbellArray, handle);
+	spin_unlock(&context->lock);
+
+	vmci_ctx_release(context);
+
+	return VMCI_HANDLE_INVALID(removedHandle) ?
+		VMCI_ERROR_NOT_FOUND : VMCI_SUCCESS;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_dbell_destroy_all --
+ *
+ *      Unregisters all doorbell handles that were previously
+ *      registered with vmci_ctx_dbell_create.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, appropriate error code otherewise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_dbell_destroy_all(uint32_t contextID)	// IN
+{
+	struct vmci_ctx *context;
+	struct vmci_handle removedHandle;
+
+	if (contextID == VMCI_INVALID_ID)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	context = vmci_ctx_get(contextID);
+	if (context == NULL)
+		return VMCI_ERROR_NOT_FOUND;
+
+	spin_lock(&context->lock);
+	do {
+		removedHandle =
+			vmci_handle_arr_remove_tail(context->doorbellArray);
+	} while (!VMCI_HANDLE_INVALID(removedHandle));
+	do {
+		removedHandle =
+			vmci_handle_arr_remove_tail(context->pendingDoorbellArray);
+	} while (!VMCI_HANDLE_INVALID(removedHandle));
+	spin_unlock(&context->lock);
+
+	vmci_ctx_release(context);
+
+	return VMCI_SUCCESS;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_notify_dbell --
+ *
+ *      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.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, appropriate error code otherewise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_notify_dbell(uint32_t srcCID,	// IN
+			  struct vmci_handle handle,	// IN
+			  uint32_t srcPrivFlags)	// IN
+{
+	struct vmci_ctx *dstContext;
+	int result;
+
+	if (VMCI_HANDLE_INVALID(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	/* Get the target VM's VMCI context. */
+	dstContext = vmci_ctx_get(handle.context);
+	if (dstContext == NULL) {
+		pr_devel("Invalid context (ID=0x%x).", handle.context);
+		return VMCI_ERROR_NOT_FOUND;
+	}
+
+	if (srcCID != handle.context) {
+		uint32_t dstPrivFlags;
+
+		if (VMCI_CONTEXT_IS_VM(srcCID)
+		    && VMCI_CONTEXT_IS_VM(handle.context)) {
+			pr_devel("Doorbell notification from VM to VM not "
+				 "supported (src=0x%x, dst=0x%x).", srcCID,
+				 handle.context);
+			result = VMCI_ERROR_DST_UNREACHABLE;
+			goto out;
+		}
+
+		result = vmci_dbell_get_priv_flags(handle, &dstPrivFlags);
+		if (result < VMCI_SUCCESS) {
+			pr_warn("Failed to get privilege flags for "
+				"destination (handle=0x%x:0x%x).",
+				handle.context, handle.resource);
+			goto out;
+		}
+
+		if (srcCID != VMCI_HOST_CONTEXT_ID ||
+		    srcPrivFlags == VMCI_NO_PRIVILEGE_FLAGS) {
+			srcPrivFlags = VMCIContext_GetPrivFlags(srcCID);
+		}
+
+		if (vmci_deny_interaction(srcPrivFlags, dstPrivFlags)) {
+			result = VMCI_ERROR_NO_ACCESS;
+			goto out;
+		}
+	}
+
+	if (handle.context == VMCI_HOST_CONTEXT_ID) {
+		result = vmci_dbell_host_context_notify(srcCID, handle);
+	} else {
+		spin_lock(&dstContext->lock);
+
+		if (!vmci_handle_arr_has_entry
+		    (dstContext->doorbellArray, handle)) {
+			result = VMCI_ERROR_NOT_FOUND;
+		} else {
+			if (!vmci_handle_arr_has_entry
+			    (dstContext->pendingDoorbellArray, handle)) {
+				vmci_handle_arr_append_entry
+					(&dstContext->pendingDoorbellArray, handle);
+
+				ctx_signal_notify(dstContext);
+				wake_up(&dstContext->hostContext.waitQueue);
+
+			}
+			result = VMCI_SUCCESS;
+		}
+		spin_unlock(&dstContext->lock);
+	}
+
+out:
+	vmci_ctx_release(dstContext);
+
+	return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * VMCI_ContextID2HostVmID --
+ *
+ *      Maps a context ID to the host specific (process/world) ID
+ *      of the VM/VMX.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, error code otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int VMCI_ContextID2HostVmID(uint32_t contextID,	// IN
+			    void *hostVmID,	// OUT
+			    size_t hostVmIDLen)	// IN
+{
+	return VMCI_ERROR_UNAVAILABLE;
+}
+
+EXPORT_SYMBOL(VMCI_ContextID2HostVmID);
+
+/*
+ *-----------------------------------------------------------------------------
+ *
+ * ctx_compare_user --
+ *
+ *      Determines whether the two users are the same.
+ *
+ * Results:
+ *      VMCI_SUCCESS if equal, error code otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *-----------------------------------------------------------------------------
+ */
+
+static int ctx_compare_user(uid_t * user1, uid_t * user2)
+{
+	if (!user1 || !user2)
+		return VMCI_ERROR_INVALID_ARGS;
+
+	return (*user1 == *user2) ? VMCI_SUCCESS : VMCI_ERROR_GENERIC;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * VMCI_IsContextOwner --
+ *
+ *      Determines whether a given host OS specific representation of
+ *      user is the owner of the VM/VMX.
+ *
+ * Results:
+ *      VMCI_SUCCESS if the hostUser is owner, error code otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int VMCI_IsContextOwner(uint32_t contextID,	// IN
+			void *hostUser)	// IN
+{
+	if (vmci_host_code_active()) {
+		struct vmci_ctx *context;
+		uid_t *user = (uid_t *) hostUser;
+		int retval;
+
+		if (!hostUser)
+			return VMCI_ERROR_INVALID_ARGS;
+
+		context = vmci_ctx_get(contextID);
+		if (!context)
+			return VMCI_ERROR_NOT_FOUND;
+
+		if (context->validUser)
+			retval = ctx_compare_user(user, &context->user);
+		else
+			retval = VMCI_ERROR_UNAVAILABLE;
+
+		vmci_ctx_release(context);
+		return retval;
+	}
+	return VMCI_ERROR_UNAVAILABLE;
+}
+
+EXPORT_SYMBOL(VMCI_IsContextOwner);
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_supports_host_qp --
+ *
+ *      Can host QPs be connected to this user process.  The answer is
+ *      false unless a sufficient version number has previously been set
+ *      by this caller.
+ *
+ * Results:
+ *      true if context supports host queue pairs, false otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+bool vmci_ctx_supports_host_qp(struct vmci_ctx * context)	// IN: Context structure
+{
+	return context && context->userVersion >= VMCI_VERSION_HOSTQP;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_qp_create --
+ *
+ *      Registers that a new queue pair handle has been allocated by
+ *      the context.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, appropriate error code otherewise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_qp_create(struct vmci_ctx *context,	// IN: Context structure
+		       struct vmci_handle handle)	// IN
+{
+	int result;
+
+	if (context == NULL || VMCI_HANDLE_INVALID(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	if (!vmci_handle_arr_has_entry(context->queuePairArray, handle)) {
+		vmci_handle_arr_append_entry(&context->queuePairArray, handle);
+		result = VMCI_SUCCESS;
+	} else {
+		result = VMCI_ERROR_DUPLICATE_ENTRY;
+	}
+
+	return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_qp_destroy --
+ *
+ *      Unregisters a queue pair handle that was previously registered
+ *      with vmci_ctx_qp_create.
+ *
+ * Results:
+ *      VMCI_SUCCESS on success, appropriate error code otherewise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_ctx_qp_destroy(struct vmci_ctx *context,	// IN: Context structure
+			struct vmci_handle handle)	// IN
+{
+	struct vmci_handle hndl;
+
+	if (context == NULL || VMCI_HANDLE_INVALID(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	hndl = vmci_handle_arr_remove_entry(context->queuePairArray, handle);
+
+	return VMCI_HANDLE_INVALID(hndl) ?
+		VMCI_ERROR_NOT_FOUND: VMCI_SUCCESS;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_ctx_qp_exists --
+ *
+ *      Determines whether a given queue pair handle is registered
+ *      with the given context.
+ *
+ * Results:
+ *      true, if queue pair is registered with context. false, otherwise.
+ *
+ * Side effects:
+ *      None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+bool vmci_ctx_qp_exists(struct vmci_ctx * context,	// IN: Context structure
+			struct vmci_handle handle)	// IN
+{
+	if (context == NULL || VMCI_HANDLE_INVALID(handle))
+		return VMCI_ERROR_INVALID_ARGS;
+
+	return vmci_handle_arr_has_entry(context->queuePairArray, handle);
+}
diff --git a/drivers/misc/vmw_vmci/vmci_context.h b/drivers/misc/vmw_vmci/vmci_context.h
new file mode 100644
index 0000000..2a576f9
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_context.h
@@ -0,0 +1,150 @@
+/*
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#ifndef _VMCI_CONTEXT_H_
+#define _VMCI_CONTEXT_H_
+
+#include <linux/vmw_vmci_defs.h>
+
+#include "vmci_datagram.h"
+#include "vmci_common_int.h"
+#include "vmci_handle_array.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 waitQueue;
+};
+
+struct vmci_ctx {
+	struct list_head listItem;	/* For global VMCI list. */
+	uint32_t cid;
+	atomic_t refCount;
+	struct list_head datagramQueue;	/* Head of per VM queue. */
+	uint32_t pendingDatagrams;
+	size_t datagramQueueSize;	/* Size of datagram queue in bytes. */
+	int userVersion;	/*
+				 * Version of the code that created
+				 * this context; e.g., VMX.
+				 */
+	spinlock_t lock;	/* Locks callQueue and handleArrays. */
+	struct vmci_handle_arr *queuePairArray;	/*
+						 * QueuePairs 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 *doorbellArray;	/* Doorbells created by context. */
+	struct vmci_handle_arr *pendingDoorbellArray;	/* Doorbells pending for context. */
+	struct vmci_handle_arr *notifierArray;	/* Contexts current context is subscribing to. */
+	struct vmci_host hostContext;
+	uint32_t privFlags;
+	uid_t user;
+	bool validUser;
+	bool *notify;		/* Notify flag pointer - hosted only. */
+	struct page *notifyPage;	/* Page backing the notify UVA. */
+};
+
+/* VMCINotifyAddRemoveInfo: Used to add/remove remote context notifications. */
+struct vmci_ctx_info {
+	uint32_t remoteCID;
+	int result;
+};
+
+/* VMCICptBufInfo: Used to set/get current context's checkpoint state. */
+struct vmci_ctx_chkpt_buf_info {
+	uint64_t cptBuf;
+	uint32_t cptType;
+	uint32_t bufSize;
+	int32_t result;
+	uint32_t _pad;
+};
+
+/*
+ * VMCINotificationReceiveInfo: Used to recieve pending notifications
+ * for doorbells and queue pairs.
+ */
+struct vmci_ctx_notify_recv_info {
+	uint64_t dbHandleBufUVA;
+	uint64_t dbHandleBufSize;
+	uint64_t qpHandleBufUVA;
+	uint64_t qpHandleBufSize;
+	int32_t result;
+	uint32_t _pad;
+};
+
+int vmci_ctx_init(void);
+int vmci_ctx_init_ctx(uint32_t cid, uint32_t flags,
+		      uintptr_t eventHnd, int version,
+		      uid_t * user, struct vmci_ctx **context);
+
+bool vmci_ctx_supports_host_qp(struct vmci_ctx *context);
+void vmci_ctx_release_ctx(struct vmci_ctx *context);
+int vmci_ctx_enqueue_dg(uint32_t cid, struct vmci_dg *dg);
+int vmci_ctx_dequeue_dg(struct vmci_ctx *context,
+			size_t * maxSize, struct vmci_dg **dg);
+int vmci_ctx_pending_dgs(uint32_t cid, uint32_t * pending);
+struct vmci_ctx *vmci_ctx_get(uint32_t cid);
+void vmci_ctx_release(struct vmci_ctx *context);
+bool vmci_ctx_exists(uint32_t cid);
+
+uint32_t vmci_ctx_get_id(struct vmci_ctx *context);
+int vmci_ctx_add_notification(uint32_t contextID, uint32_t remoteCID);
+int vmci_ctx_remove_notification(uint32_t contextID, uint32_t remoteCID);
+int vmci_ctx_get_chkpt_state(uint32_t contextID, uint32_t cptType,
+			     uint32_t * numCIDs, char **cptBufPtr);
+int vmci_ctx_set_chkpt_state(uint32_t contextID, uint32_t cptType,
+			     uint32_t numCIDs, char *cptBuf);
+
+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(uint32_t contextID, struct vmci_handle handle);
+int vmci_ctx_dbell_destroy(uint32_t contextID, struct vmci_handle handle);
+int vmci_ctx_dbell_destroy_all(uint32_t contextID);
+int vmci_ctx_notify_dbell(uint32_t cid, struct vmci_handle handle,
+			  uint32_t srcPrivFlags);
+
+int vmci_ctx_rcv_notifications_get(uint32_t contextID, struct vmci_handle_arr
+				   **dbHandleArray, struct vmci_handle_arr
+				   **qpHandleArray);
+void vmci_ctx_rcv_notifications_release(uint32_t contextID, struct vmci_handle_arr
+					*dbHandleArray, struct vmci_handle_arr
+					*qpHandleArray, bool success);
+#endif				// _VMCI_CONTEXT_H_
-- 
1.7.0.4