diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index c255984..405e05a 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -909,6 +909,7 @@
 	CHANNEL_OFFER_STATE,
 	CHANNEL_OPENING_STATE,
 	CHANNEL_OPEN_STATE,
+	CHANNEL_OPENED_STATE,
 };
 
 struct vmbus_channel_debug_info {
@@ -1046,6 +1047,38 @@
 	 * preserve the earlier behavior.
 	 */
 	u32 target_vp;
+	/*
+	 * Support for sub-channels. For high performance devices,
+	 * it will be useful to have multiple sub-channels to support
+	 * a scalable communication infrastructure with the host.
+	 * The support for sub-channels is implemented as an extention
+	 * to the current infrastructure.
+	 * The initial offer is considered the primary channel and this
+	 * offer message will indicate if the host supports sub-channels.
+	 * The guest is free to ask for sub-channels to be offerred and can
+	 * open these sub-channels as a normal "primary" channel. However,
+	 * all sub-channels will have the same type and instance guids as the
+	 * primary channel. Requests sent on a given channel will result in a
+	 * response on the same channel.
+	 */
+
+	/*
+	 * Sub-channel creation callback. This callback will be called in
+	 * process context when a sub-channel offer is received from the host.
+	 * The guest can open the sub-channel in the context of this callback.
+	 */
+	void (*sc_creation_callback)(struct vmbus_channel *new_sc);
+
+	spinlock_t sc_lock;
+	/*
+	 * All Sub-channels of a primary channel are linked here.
+	 */
+	struct list_head sc_list;
+	/*
+	 * The primary channel this sub-channel belongs to.
+	 * This will be NULL for the primary channel.
+	 */
+	struct vmbus_channel *primary_channel;
 };
 
 static inline void set_channel_read_state(struct vmbus_channel *c, bool state)
@@ -1057,6 +1090,34 @@
 
 int vmbus_request_offers(void);
 
+/*
+ * APIs for managing sub-channels.
+ */
+
+void vmbus_set_sc_create_callback(struct vmbus_channel *primary_channel,
+			void (*sc_cr_cb)(struct vmbus_channel *new_sc));
+
+/*
+ * Retrieve the (sub) channel on which to send an outgoing request.
+ * When a primary channel has multiple sub-channels, we choose a
+ * channel whose VCPU binding is closest to the VCPU on which
+ * this call is being made.
+ */
+struct vmbus_channel *vmbus_get_outgoing_channel(struct vmbus_channel *primary);
+
+/*
+ * Check if sub-channels have already been offerred. This API will be useful
+ * when the driver is unloaded after establishing sub-channels. In this case,
+ * when the driver is re-loaded, the driver would have to check if the
+ * subchannels have already been established before attempting to request
+ * the creation of sub-channels.
+ * This function returns TRUE to indicate that subchannels have already been
+ * created.
+ * This function should be invoked after setting the callback function for
+ * sub-channel creation.
+ */
+bool vmbus_are_subchannels_present(struct vmbus_channel *primary);
+
 /* The format must be the same as struct vmdata_gpa_direct */
 struct vmbus_channel_packet_page_buffer {
 	u16 type;
@@ -1327,7 +1388,6 @@
 			0x8e, 0x77, 0x05, 0x58, 0xeb, 0x10, 0x73, 0xf8 \
 		}
 
-
 /*
  * Common header for Hyper-V ICs
  */