misc: IBM Virtual Management Channel Driver (VMC)

This driver is a logical device which provides an
interface between the hypervisor and a management
partition. This interface is like a message
passing interface. This management partition
is intended to provide an alternative to HMC-based
system management.

VMC enables the Management LPAR to provide basic
logical partition functions:
- Logical Partition Configuration
- Boot, start, and stop actions for individual
partitions
- Display of partition status
- Management of virtual Ethernet
- Management of virtual Storage
- Basic system management

This driver is to be used for the POWER Virtual
Management Channel Virtual Adapter on the PowerPC
platform. It provides a character device which
allows for both request/response and async message
support through the /dev/ibmvmc node.

Signed-off-by: Bryant G. Ly <[e-mail]>
Reviewed-by: Steven Royer <[e-mail]>
Reviewed-by: Adam Reznechek <[e-mail]>
Reviewed-by: Randy Dunlap <[e-mail]>
Tested-by: Taylor Jakobson <[e-mail]>
Tested-by: Brad Warrum <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/ioctl/ioctl-number.txt

···
 0xCA	80-BF	uapi/scsi/cxlflash_ioctl.h
 0xCB	00-1F	CBM serial IEC bus	in development:
 					<mailto:[e-mail]>
+0xCC	00-0F	drivers/misc/ibmvmc.h    pseries VMC driver
 0xCD	01	linux/reiserfs_fs.h
 0xCF	02	fs/cifs/ioctl.c
 0xDB	00-0F	drivers/char/mwave/mwavepub.h

Documentation/misc-devices/ibmvmc.rst

···
+.. SPDX-License-Identifier: GPL-2.0+
+======================================================
+IBM Virtual Management Channel Kernel Driver (IBMVMC)
+======================================================
+
+:Authors:
+	Dave Engebretsen <[e-mail]>,
+	Adam Reznechek <[e-mail]>,
+	Steven Royer <[e-mail]>,
+	Bryant G. Ly <[e-mail]>,
+
+Introduction
+============
+
+Note: Knowledge of virtualization technology is required to understand
+this document.
+
+A good reference document would be:
+
+https://openpowerfoundation.org/wp-content/uploads/2016/05/LoPAPR_DRAFT_v11_24March2016_cmt1.pdf
+
+The Virtual Management Channel (VMC) is a logical device which provides an
+interface between the hypervisor and a management partition. This interface
+is like a message passing interface. This management partition is intended
+to provide an alternative to systems that use a Hardware Management
+Console (HMC) - based system management.
+
+The primary hardware management solution that is developed by IBM relies
+on an appliance server named the Hardware Management Console (HMC),
+packaged as an external tower or rack-mounted personal computer. In a
+Power Systems environment, a single HMC can manage multiple POWER
+processor-based systems.
+
+Management Application
+----------------------
+
+In the management partition, a management application exists which enables
+a system administrator to configure the system’s partitioning
+characteristics via a command line interface (CLI) or Representational
+State Transfer Application (REST API's).
+
+The management application runs on a Linux logical partition on a
+POWER8 or newer processor-based server that is virtualized by PowerVM.
+System configuration, maintenance, and control functions which
+traditionally require an HMC can be implemented in the management
+application using a combination of HMC to hypervisor interfaces and
+existing operating system methods. This tool provides a subset of the
+functions implemented by the HMC and enables basic partition configuration.
+The set of HMC to hypervisor messages supported by the management
+application component are passed to the hypervisor over a VMC interface,
+which is defined below.
+
+The VMC enables the management partition to provide basic partitioning
+functions:
+
+- Logical Partitioning Configuration
+- Start, and stop actions for individual partitions
+- Display of partition status
+- Management of virtual Ethernet
+- Management of virtual Storage
+- Basic system management
+
+Virtual Management Channel (VMC)
+--------------------------------
+
+A logical device, called the Virtual Management Channel (VMC), is defined
+for communicating between the management application and the hypervisor. It
+basically creates the pipes that enable virtualization management
+software. This device is presented to a designated management partition as
+a virtual device.
+
+This communication device uses Command/Response Queue (CRQ) and the
+Remote Direct Memory Access (RDMA) interfaces. A three-way handshake is
+defined that must take place to establish that both the hypervisor and
+management partition sides of the channel are running prior to
+sending/receiving any of the protocol messages.
+
+This driver also utilizes Transport Event CRQs. CRQ messages are sent
+when the hypervisor detects one of the peer partitions has abnormally
+terminated, or one side has called H_FREE_CRQ to close their CRQ.
+Two new classes of CRQ messages are introduced for the VMC device. VMC
+Administrative messages are used for each partition using the VMC to
+communicate capabilities to their partner. HMC Interface messages are used
+for the actual flow of HMC messages between the management partition and
+the hypervisor. As most HMC messages far exceed the size of a CRQ buffer,
+a virtual DMA (RMDA) of the HMC message data is done prior to each HMC
+Interface CRQ message. Only the management partition drives RDMA
+operations; hypervisors never directly cause the movement of message data.
+
+
+Terminology
+-----------
+RDMA
+        Remote Direct Memory Access is DMA transfer from the server to its
+        client or from the server to its partner partition. DMA refers
+        to both physical I/O to and from memory operations and to memory
+        to memory move operations.
+CRQ
+        Command/Response Queue a facility which is used to communicate
+        between partner partitions. Transport events which are signaled
+        from the hypervisor to partition are also reported in this queue.
+
+Example Management Partition VMC Driver Interface
+=================================================
+
+This section provides an example for the management application
+implementation where a device driver is used to interface to the VMC
+device. This driver consists of a new device, for example /dev/ibmvmc,
+which provides interfaces to open, close, read, write, and perform
+ioctl’s against the VMC device.
+
+VMC Interface Initialization
+----------------------------
+
+The device driver is responsible for initializing the VMC when the driver
+is loaded. It first creates and initializes the CRQ. Next, an exchange of
+VMC capabilities is performed to indicate the code version and number of
+resources available in both the management partition and the hypervisor.
+Finally, the hypervisor requests that the management partition create an
+initial pool of VMC buffers, one buffer for each possible HMC connection,
+which will be used for management application  session initialization.
+Prior to completion of this initialization sequence, the device returns
+EBUSY to open() calls. EIO is returned for all open() failures.
+
+::
+
+        Management Partition		Hypervisor
+                        CRQ INIT
+        ---------------------------------------->
+        	   CRQ INIT COMPLETE
+        <----------------------------------------
+        	      CAPABILITIES
+        ---------------------------------------->
+        	 CAPABILITIES RESPONSE
+        <----------------------------------------
+              ADD BUFFER (HMC IDX=0,1,..)         _
+        <----------------------------------------  |
+        	  ADD BUFFER RESPONSE              | - Perform # HMCs Iterations
+        ----------------------------------------> -
+
+VMC Interface Open
+------------------
+
+After the basic VMC channel has been initialized, an HMC session level
+connection can be established. The application layer performs an open() to
+the VMC device and executes an ioctl() against it, indicating the HMC ID
+(32 bytes of data) for this session. If the VMC device is in an invalid
+state, EIO will be returned for the ioctl(). The device driver creates a
+new HMC session value (ranging from 1 to 255) and HMC index value (starting
+at index 0 and ranging to 254) for this HMC ID. The driver then does an
+RDMA of the HMC ID to the hypervisor, and then sends an Interface Open
+message to the hypervisor to establish the session over the VMC. After the
+hypervisor receives this information, it sends Add Buffer messages to the
+management partition to seed an initial pool of buffers for the new HMC
+connection. Finally, the hypervisor sends an Interface Open Response
+message, to indicate that it is ready for normal runtime messaging. The
+following illustrates this VMC flow:
+
+::
+
+        Management Partition             Hypervisor
+        	      RDMA HMC ID
+        ---------------------------------------->
+        	    Interface Open
+        ---------------------------------------->
+        	      Add Buffer                  _
+        <----------------------------------------  |
+        	  Add Buffer Response              | - Perform N Iterations
+        ----------------------------------------> -
+        	Interface Open Response
+        <----------------------------------------
+
+VMC Interface Runtime
+---------------------
+
+During normal runtime, the management application and the hypervisor
+exchange HMC messages via the Signal VMC message and RDMA operations. When
+sending data to the hypervisor, the management application performs a
+write() to the VMC device, and the driver RDMA’s the data to the hypervisor
+and then sends a Signal Message. If a write() is attempted before VMC
+device buffers have been made available by the hypervisor, or no buffers
+are currently available, EBUSY is returned in response to the write(). A
+write() will return EIO for all other errors, such as an invalid device
+state. When the hypervisor sends a message to the management, the data is
+put into a VMC buffer and an Signal Message is sent to the VMC driver in
+the management partition. The driver RDMA’s the buffer into the partition
+and passes the data up to the appropriate management application via a
+read() to the VMC device. The read() request blocks if there is no buffer
+available to read. The management application may use select() to wait for
+the VMC device to become ready with data to read.
+
+::
+
+        Management Partition             Hypervisor
+        		MSG RDMA
+        ---------------------------------------->
+        		SIGNAL MSG
+        ---------------------------------------->
+        		SIGNAL MSG
+        <----------------------------------------
+        		MSG RDMA
+        <----------------------------------------
+
+VMC Interface Close
+-------------------
+
+HMC session level connections are closed by the management partition when
+the application layer performs a close() against the device. This action
+results in an Interface Close message flowing to the hypervisor, which
+causes the session to be terminated. The device driver must free any
+storage allocated for buffers for this HMC connection.
+
+::
+
+        Management Partition             Hypervisor
+        	     INTERFACE CLOSE
+        ---------------------------------------->
+                INTERFACE CLOSE RESPONSE
+        <----------------------------------------
+
+Additional Information
+======================
+
+For more information on the documentation for CRQ Messages, VMC Messages,
+HMC interface Buffers, and signal messages please refer to the Linux on
+Power Architecture Platform Reference. Section F.

MAINTAINERS

···
 S:	Supported
 F:	drivers/scsi/ibmvscsi/ibmvfc*
 
+IBM Power Virtual Management Channel Driver
+M:	Bryant G. Ly <[e-mail]>
+M:	Steven Royer <[e-mail]>
+S:	Supported
+F:	drivers/misc/ibmvmc.*
+
 IBM Power Virtual SCSI Device Drivers
 M:	Tyrel Datwyler <[e-mail]>
 L:	[e-mail]

arch/powerpc/include/asm/hvcall.h

···
 #define H_GET_MPP_X		0x314
 #define H_SET_MODE		0x31C
 #define H_CLEAR_HPT		0x358
+#define H_REQUEST_VMC		0x360
 #define H_RESIZE_HPT_PREPARE	0x36C
 #define H_RESIZE_HPT_COMMIT	0x370
 #define H_REGISTER_PROC_TBL	0x37C

drivers/misc/Kconfig

···
 	  for information on the specific driver level and support statement
 	  for your IBM server.
 
+config IBMVMC
+	tristate "IBM Virtual Management Channel support"
+	depends on PPC_PSERIES
+	help
+	  This is the IBM POWER Virtual Management Channel
+
+	  This driver is to be used for the POWER Virtual
+	  Management Channel virtual adapter on the PowerVM
+	  platform. It provides both request/response and
+	  async message support through the /dev/ibmvmc node.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ibmvmc.
+
 config PHANTOM
 	tristate "Sensable PHANToM (PCI)"
 	depends on PCI

drivers/misc/Makefile

···
 #
 
 obj-$(CONFIG_IBM_ASM)		+= ibmasm/
+obj-$(CONFIG_IBMVMC)		+= ibmvmc.o
 obj-$(CONFIG_AD525X_DPOT)	+= ad525x_dpot.o
 obj-$(CONFIG_AD525X_DPOT_I2C)	+= ad525x_dpot-i2c.o
 obj-$(CONFIG_AD525X_DPOT_SPI)	+= ad525x_dpot-spi.o

drivers/misc/ibmvmc.c

···
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * IBM Power Systems Virtual Management Channel Support.
+ *
+ * Copyright (c) 2004, 2018 IBM Corp.
+ *   Dave Engebretsen [e-mail]
+ *   Steven Royer [e-mail]
+ *   Adam Reznechek [e-mail]
+ *   Bryant G. Ly <[e-mail]>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/major.h>
+#include <linux/string.h>
+#include <linux/fcntl.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/percpu.h>
+#include <linux/delay.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
+#include <linux/miscdevice.h>
+#include <linux/sched/signal.h>
+
+#include <asm/byteorder.h>
+#include <asm/irq.h>
+#include <asm/vio.h>
+
+#include "ibmvmc.h"
+
+#define IBMVMC_DRIVER_VERSION "1.0"
+
+/*
+ * Static global variables
+ */
+static DECLARE_WAIT_QUEUE_HEAD(ibmvmc_read_wait);
+
+static const char ibmvmc_driver_name[] = "ibmvmc";
+
+static struct ibmvmc_struct ibmvmc;
+static struct ibmvmc_hmc hmcs[MAX_HMCS];
+static struct crq_server_adapter ibmvmc_adapter;
+
+static int ibmvmc_max_buf_pool_size = DEFAULT_BUF_POOL_SIZE;
+static int ibmvmc_max_hmcs = DEFAULT_HMCS;
+static int ibmvmc_max_mtu = DEFAULT_MTU;
+
+static inline long h_copy_rdma(s64 length, u64 sliobn, u64 slioba,
+			       u64 dliobn, u64 dlioba)
+{
+	long rc = 0;
+
+	/* Ensure all writes to source memory are visible before hcall */
+	dma_wmb();
+	pr_debug("ibmvmc: h_copy_rdma(0x%llx, 0x%llx, 0x%llx, 0x%llx, 0x%llx\n",
+		 length, sliobn, slioba, dliobn, dlioba);
+	rc = plpar_hcall_norets(H_COPY_RDMA, length, sliobn, slioba,
+				dliobn, dlioba);
+	pr_debug("ibmvmc: h_copy_rdma rc = 0x%lx\n", rc);
+
+	return rc;
+}
+
+static inline void h_free_crq(uint32_t unit_address)
+{
+	long rc = 0;
+
+	do {
+		if (H_IS_LONG_BUSY(rc))
+			msleep(get_longbusy_msecs(rc));
+
+		rc = plpar_hcall_norets(H_FREE_CRQ, unit_address);
+	} while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
+}
+
+/**
+ * h_request_vmc: - request a hypervisor virtual management channel device
+ * @vmc_index: drc index of the vmc device created
+ *
+ * Requests the hypervisor create a new virtual management channel device,
+ * allowing this partition to send hypervisor virtualization control
+ * commands.
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static inline long h_request_vmc(u32 *vmc_index)
+{
+	long rc = 0;
+	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
+
+	do {
+		if (H_IS_LONG_BUSY(rc))
+			msleep(get_longbusy_msecs(rc));
+
+		/* Call to request the VMC device from phyp */
+		rc = plpar_hcall(H_REQUEST_VMC, retbuf);
+		pr_debug("ibmvmc: %s rc = 0x%lx\n", __func__, rc);
+		*vmc_index = retbuf[0];
+	} while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
+
+	return rc;
+}
+
+/* routines for managing a command/response queue */
+/**
+ * ibmvmc_handle_event: - Interrupt handler for crq events
+ * @irq:        number of irq to handle, not used
+ * @dev_instance: crq_server_adapter that received interrupt
+ *
+ * Disables interrupts and schedules ibmvmc_task
+ *
+ * Always returns IRQ_HANDLED
+ */
+static irqreturn_t ibmvmc_handle_event(int irq, void *dev_instance)
+{
+	struct crq_server_adapter *adapter =
+		(struct crq_server_adapter *)dev_instance;
+
+	vio_disable_interrupts(to_vio_dev(adapter->dev));
+	tasklet_schedule(&adapter->work_task);
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * ibmvmc_release_crq_queue - Release CRQ Queue
+ *
+ * @adapter:	crq_server_adapter struct
+ *
+ * Return:
+ *	0 - Success
+ *	Non-Zero - Failure
+ */
+static void ibmvmc_release_crq_queue(struct crq_server_adapter *adapter)
+{
+	struct vio_dev *vdev = to_vio_dev(adapter->dev);
+	struct crq_queue *queue = &adapter->queue;
+
+	free_irq(vdev->irq, (void *)adapter);
+	tasklet_kill(&adapter->work_task);
+
+	if (adapter->reset_task)
+		kthread_stop(adapter->reset_task);
+
+	h_free_crq(vdev->unit_address);
+	dma_unmap_single(adapter->dev,
+			 queue->msg_token,
+			 queue->size * sizeof(*queue->msgs), DMA_BIDIRECTIONAL);
+	free_page((unsigned long)queue->msgs);
+}
+
+/**
+ * ibmvmc_reset_crq_queue - Reset CRQ Queue
+ *
+ * @adapter:	crq_server_adapter struct
+ *
+ * This function calls h_free_crq and then calls H_REG_CRQ and does all the
+ * bookkeeping to get us back to where we can communicate.
+ *
+ * Return:
+ *	0 - Success
+ *	Non-Zero - Failure
+ */
+static int ibmvmc_reset_crq_queue(struct crq_server_adapter *adapter)
+{
+	struct vio_dev *vdev = to_vio_dev(adapter->dev);
+	struct crq_queue *queue = &adapter->queue;
+	int rc = 0;
+
+	/* Close the CRQ */
+	h_free_crq(vdev->unit_address);
+
+	/* Clean out the queue */
+	memset(queue->msgs, 0x00, PAGE_SIZE);
+	queue->cur = 0;
+
+	/* And re-open it again */
+	rc = plpar_hcall_norets(H_REG_CRQ,
+				vdev->unit_address,
+				queue->msg_token, PAGE_SIZE);
+	if (rc == 2)
+		/* Adapter is good, but other end is not ready */
+		dev_warn(adapter->dev, "Partner adapter not ready\n");
+	else if (rc != 0)
+		dev_err(adapter->dev, "couldn't register crq--rc 0x%x\n", rc);
+
+	return rc;
+}
+
+/**
+ * crq_queue_next_crq: - Returns the next entry in message queue
+ * @queue:      crq_queue to use
+ *
+ * Returns pointer to next entry in queue, or NULL if there are no new
+ * entried in the CRQ.
+ */
+static struct ibmvmc_crq_msg *crq_queue_next_crq(struct crq_queue *queue)
+{
+	struct ibmvmc_crq_msg *crq;
+	unsigned long flags;
+
+	spin_lock_irqsave(&queue->lock, flags);
+	crq = &queue->msgs[queue->cur];
+	if (crq->valid & 0x80) {
+		if (++queue->cur == queue->size)
+			queue->cur = 0;
+
+		/* Ensure the read of the valid bit occurs before reading any
+		 * other bits of the CRQ entry
+		 */
+		dma_rmb();
+	} else {
+		crq = NULL;
+	}
+
+	spin_unlock_irqrestore(&queue->lock, flags);
+
+	return crq;
+}
+
+/**
+ * ibmvmc_send_crq - Send CRQ
+ *
+ * @adapter:	crq_server_adapter struct
+ * @word1:	Word1 Data field
+ * @word2:	Word2 Data field
+ *
+ * Return:
+ *	0 - Success
+ *	Non-Zero - Failure
+ */
+static long ibmvmc_send_crq(struct crq_server_adapter *adapter,
+			    u64 word1, u64 word2)
+{
+	struct vio_dev *vdev = to_vio_dev(adapter->dev);
+	long rc = 0;
+
+	dev_dbg(adapter->dev, "(0x%x, 0x%016llx, 0x%016llx)\n",
+		vdev->unit_address, word1, word2);
+
+	/*
+	 * Ensure the command buffer is flushed to memory before handing it
+	 * over to the other side to prevent it from fetching any stale data.
+	 */
+	dma_wmb();
+	rc = plpar_hcall_norets(H_SEND_CRQ, vdev->unit_address, word1, word2);
+	dev_dbg(adapter->dev, "rc = 0x%lx\n", rc);
+
+	return rc;
+}
+
+/**
+ * alloc_dma_buffer - Create DMA Buffer
+ *
+ * @vdev:	vio_dev struct
+ * @size:	Size field
+ * @dma_handle:	DMA address field
+ *
+ * Allocates memory for the command queue and maps remote memory into an
+ * ioba.
+ *
+ * Returns a pointer to the buffer
+ */
+static void *alloc_dma_buffer(struct vio_dev *vdev, size_t size,
+			      dma_addr_t *dma_handle)
+{
+	/* allocate memory */
+	void *buffer = kzalloc(size, GFP_KERNEL);
+
+	if (!buffer) {
+		*dma_handle = 0;
+		return NULL;
+	}
+
+	/* DMA map */
+	*dma_handle = dma_map_single(&vdev->dev, buffer, size,
+				     DMA_BIDIRECTIONAL);
+
+	if (dma_mapping_error(&vdev->dev, *dma_handle)) {
+		*dma_handle = 0;
+		kzfree(buffer);
+		return NULL;
+	}
+
+	return buffer;
+}
+
+/**
+ * free_dma_buffer - Free DMA Buffer
+ *
+ * @vdev:	vio_dev struct
+ * @size:	Size field
+ * @vaddr:	Address field
+ * @dma_handle:	DMA address field
+ *
+ * Releases memory for a command queue and unmaps mapped remote memory.
+ */
+static void free_dma_buffer(struct vio_dev *vdev, size_t size, void *vaddr,
+			    dma_addr_t dma_handle)
+{
+	/* DMA unmap */
+	dma_unmap_single(&vdev->dev, dma_handle, size, DMA_BIDIRECTIONAL);
+
+	/* deallocate memory */
+	kzfree(vaddr);
+}
+
+/**
+ * ibmvmc_get_valid_hmc_buffer - Retrieve Valid HMC Buffer
+ *
+ * @hmc_index:	HMC Index Field
+ *
+ * Return:
+ *	Pointer to ibmvmc_buffer
+ */
+static struct ibmvmc_buffer *ibmvmc_get_valid_hmc_buffer(u8 hmc_index)
+{
+	struct ibmvmc_buffer *buffer;
+	struct ibmvmc_buffer *ret_buf = NULL;
+	unsigned long i;
+
+	if (hmc_index > ibmvmc.max_hmc_index)
+		return NULL;
+
+	buffer = hmcs[hmc_index].buffer;
+
+	for (i = 0; i < ibmvmc_max_buf_pool_size; i++) {
+		if (buffer[i].valid && buffer[i].free &&
+		    buffer[i].owner == VMC_BUF_OWNER_ALPHA) {
+			buffer[i].free = 0;
+			ret_buf = &buffer[i];
+			break;
+		}
+	}
+
+	return ret_buf;
+}
+
+/**
+ * ibmvmc_get_free_hmc_buffer - Get Free HMC Buffer
+ *
+ * @adapter:	crq_server_adapter struct
+ * @hmc_index:	Hmc Index field
+ *
+ * Return:
+ *	Pointer to ibmvmc_buffer
+ */
+static struct ibmvmc_buffer *ibmvmc_get_free_hmc_buffer(struct crq_server_adapter *adapter,
+							u8 hmc_index)
+{
+	struct ibmvmc_buffer *buffer;
+	struct ibmvmc_buffer *ret_buf = NULL;
+	unsigned long i;
+
+	if (hmc_index > ibmvmc.max_hmc_index) {
+		dev_info(adapter->dev, "get_free_hmc_buffer: invalid hmc_index=0x%x\n",
+			 hmc_index);
+		return NULL;
+	}
+
+	buffer = hmcs[hmc_index].buffer;
+
+	for (i = 0; i < ibmvmc_max_buf_pool_size; i++) {
+		if (buffer[i].free &&
+		    buffer[i].owner == VMC_BUF_OWNER_ALPHA) {
+			buffer[i].free = 0;
+			ret_buf = &buffer[i];
+			break;
+		}
+	}
+
+	return ret_buf;
+}
+
+/**
+ * ibmvmc_free_hmc_buffer - Free an HMC Buffer
+ *
+ * @hmc:	ibmvmc_hmc struct
+ * @buffer:	ibmvmc_buffer struct
+ *
+ */
+static void ibmvmc_free_hmc_buffer(struct ibmvmc_hmc *hmc,
+				   struct ibmvmc_buffer *buffer)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&hmc->lock, flags);
+	buffer->free = 1;
+	spin_unlock_irqrestore(&hmc->lock, flags);
+}
+
+/**
+ * ibmvmc_count_hmc_buffers - Count HMC Buffers
+ *
+ * @hmc_index:	HMC Index field
+ * @valid:	Valid number of buffers field
+ * @free:	Free number of buffers field
+ *
+ */
+static void ibmvmc_count_hmc_buffers(u8 hmc_index, unsigned int *valid,
+				     unsigned int *free)
+{
+	struct ibmvmc_buffer *buffer;
+	unsigned long i;
+	unsigned long flags;
+
+	if (hmc_index > ibmvmc.max_hmc_index)
+		return;
+
+	if (!valid || !free)
+		return;
+
+	*valid = 0; *free = 0;
+
+	buffer = hmcs[hmc_index].buffer;
+	spin_lock_irqsave(&hmcs[hmc_index].lock, flags);
+
+	for (i = 0; i < ibmvmc_max_buf_pool_size; i++) {
+		if (buffer[i].valid) {
+			*valid = *valid + 1;
+			if (buffer[i].free)
+				*free = *free + 1;
+		}
+	}
+
+	spin_unlock_irqrestore(&hmcs[hmc_index].lock, flags);
+}
+
+/**
+ * ibmvmc_get_free_hmc - Get Free HMC
+ *
+ * Return:
+ *	Pointer to an available HMC Connection
+ *	Null otherwise
+ */
+static struct ibmvmc_hmc *ibmvmc_get_free_hmc(void)
+{
+	unsigned long i;
+	unsigned long flags;
+
+	/*
+	 * Find an available HMC connection.
+	 */
+	for (i = 0; i <= ibmvmc.max_hmc_index; i++) {
+		spin_lock_irqsave(&hmcs[i].lock, flags);
+		if (hmcs[i].state == ibmhmc_state_free) {
+			hmcs[i].index = i;
+			hmcs[i].state = ibmhmc_state_initial;
+			spin_unlock_irqrestore(&hmcs[i].lock, flags);
+			return &hmcs[i];
+		}
+		spin_unlock_irqrestore(&hmcs[i].lock, flags);
+	}
+
+	return NULL;
+}
+
+/**
+ * ibmvmc_return_hmc - Return an HMC Connection
+ *
+ * @hmc:		ibmvmc_hmc struct
+ * @release_readers:	Number of readers connected to session
+ *
+ * This function releases the HMC connections back into the pool.
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static int ibmvmc_return_hmc(struct ibmvmc_hmc *hmc, bool release_readers)
+{
+	struct ibmvmc_buffer *buffer;
+	struct crq_server_adapter *adapter;
+	struct vio_dev *vdev;
+	unsigned long i;
+	unsigned long flags;
+
+	if (!hmc || !hmc->adapter)
+		return -EIO;
+
+	if (release_readers) {
+		if (hmc->file_session) {
+			struct ibmvmc_file_session *session = hmc->file_session;
+
+			session->valid = 0;
+			wake_up_interruptible(&ibmvmc_read_wait);
+		}
+	}
+
+	adapter = hmc->adapter;
+	vdev = to_vio_dev(adapter->dev);
+
+	spin_lock_irqsave(&hmc->lock, flags);
+	hmc->index = 0;
+	hmc->state = ibmhmc_state_free;
+	hmc->queue_head = 0;
+	hmc->queue_tail = 0;
+	buffer = hmc->buffer;
+	for (i = 0; i < ibmvmc_max_buf_pool_size; i++) {
+		if (buffer[i].valid) {
+			free_dma_buffer(vdev,
+					ibmvmc.max_mtu,
+					buffer[i].real_addr_local,
+					buffer[i].dma_addr_local);
+			dev_dbg(adapter->dev, "Forgot buffer id 0x%lx\n", i);
+		}
+		memset(&buffer[i], 0, sizeof(struct ibmvmc_buffer));
+
+		hmc->queue_outbound_msgs[i] = VMC_INVALID_BUFFER_ID;
+	}
+
+	spin_unlock_irqrestore(&hmc->lock, flags);
+
+	return 0;
+}
+
+/**
+ * ibmvmc_send_open - Interface Open
+ * @buffer: Pointer to ibmvmc_buffer struct
+ * @hmc: Pointer to ibmvmc_hmc struct
+ *
+ * This command is sent by the management partition as the result of a
+ * management partition device request. It causes the hypervisor to
+ * prepare a set of data buffers for the management application connection
+ * indicated HMC idx. A unique HMC Idx would be used if multiple management
+ * applications running concurrently were desired. Before responding to this
+ * command, the hypervisor must provide the management partition with at
+ * least one of these new buffers via the Add Buffer. This indicates whether
+ * the messages are inbound or outbound from the hypervisor.
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static int ibmvmc_send_open(struct ibmvmc_buffer *buffer,
+			    struct ibmvmc_hmc *hmc)
+{
+	struct ibmvmc_crq_msg crq_msg;
+	struct crq_server_adapter *adapter;
+	__be64 *crq_as_u64 = (__be64 *)&crq_msg;
+	int rc = 0;
+
+	if (!hmc || !hmc->adapter)
+		return -EIO;
+
+	adapter = hmc->adapter;
+
+	dev_dbg(adapter->dev, "send_open: 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
+		(unsigned long)buffer->size, (unsigned long)adapter->liobn,
+		(unsigned long)buffer->dma_addr_local,
+		(unsigned long)adapter->riobn,
+		(unsigned long)buffer->dma_addr_remote);
+
+	rc = h_copy_rdma(buffer->size,
+			 adapter->liobn,
+			 buffer->dma_addr_local,
+			 adapter->riobn,
+			 buffer->dma_addr_remote);
+	if (rc) {
+		dev_err(adapter->dev, "Error: In send_open, h_copy_rdma rc 0x%x\n",
+			rc);
+		return -EIO;
+	}
+
+	hmc->state = ibmhmc_state_opening;
+
+	crq_msg.valid = 0x80;
+	crq_msg.type = VMC_MSG_OPEN;
+	crq_msg.status = 0;
+	crq_msg.var1.rsvd = 0;
+	crq_msg.hmc_session = hmc->session;
+	crq_msg.hmc_index = hmc->index;
+	crq_msg.var2.buffer_id = cpu_to_be16(buffer->id);
+	crq_msg.rsvd = 0;
+	crq_msg.var3.rsvd = 0;
+
+	ibmvmc_send_crq(adapter, be64_to_cpu(crq_as_u64[0]),
+			be64_to_cpu(crq_as_u64[1]));
+
+	return rc;
+}
+
+/**
+ * ibmvmc_send_close - Interface Close
+ * @hmc: Pointer to ibmvmc_hmc struct
+ *
+ * This command is sent by the management partition to terminate a
+ * management application to hypervisor connection. When this command is
+ * sent, the management partition has quiesced all I/O operations to all
+ * buffers associated with this management application connection, and
+ * has freed any storage for these buffers.
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static int ibmvmc_send_close(struct ibmvmc_hmc *hmc)
+{
+	struct ibmvmc_crq_msg crq_msg;
+	struct crq_server_adapter *adapter;
+	__be64 *crq_as_u64 = (__be64 *)&crq_msg;
+	int rc = 0;
+
+	if (!hmc || !hmc->adapter)
+		return -EIO;
+
+	adapter = hmc->adapter;
+
+	dev_info(adapter->dev, "CRQ send: close\n");
+
+	crq_msg.valid = 0x80;
+	crq_msg.type = VMC_MSG_CLOSE;
+	crq_msg.status = 0;
+	crq_msg.var1.rsvd = 0;
+	crq_msg.hmc_session = hmc->session;
+	crq_msg.hmc_index = hmc->index;
+	crq_msg.var2.rsvd = 0;
+	crq_msg.rsvd = 0;
+	crq_msg.var3.rsvd = 0;
+
+	ibmvmc_send_crq(adapter, be64_to_cpu(crq_as_u64[0]),
+			be64_to_cpu(crq_as_u64[1]));
+
+	return rc;
+}
+
+/**
+ * ibmvmc_send_capabilities - Send VMC Capabilities
+ *
+ * @adapter:	crq_server_adapter struct
+ *
+ * The capabilities message is an administrative message sent after the CRQ
+ * initialization sequence of messages and is used to exchange VMC capabilities
+ * between the management partition and the hypervisor. The management
+ * partition must send this message and the hypervisor must respond with VMC
+ * capabilities Response message before HMC interface message can begin. Any
+ * HMC interface messages received before the exchange of capabilities has
+ * complete are dropped.
+ *
+ * Return:
+ *	0 - Success
+ */
+static int ibmvmc_send_capabilities(struct crq_server_adapter *adapter)
+{
+	struct ibmvmc_admin_crq_msg crq_msg;
+	__be64 *crq_as_u64 = (__be64 *)&crq_msg;
+
+	dev_dbg(adapter->dev, "ibmvmc: CRQ send: capabilities\n");
+	crq_msg.valid = 0x80;
+	crq_msg.type = VMC_MSG_CAP;
+	crq_msg.status = 0;
+	crq_msg.rsvd[0] = 0;
+	crq_msg.rsvd[1] = 0;
+	crq_msg.max_hmc = ibmvmc_max_hmcs;
+	crq_msg.max_mtu = cpu_to_be32(ibmvmc_max_mtu);
+	crq_msg.pool_size = cpu_to_be16(ibmvmc_max_buf_pool_size);
+	crq_msg.crq_size = cpu_to_be16(adapter->queue.size);
+	crq_msg.version = cpu_to_be16(IBMVMC_PROTOCOL_VERSION);
+
+	ibmvmc_send_crq(adapter, be64_to_cpu(crq_as_u64[0]),
+			be64_to_cpu(crq_as_u64[1]));
+
+	ibmvmc.state = ibmvmc_state_capabilities;
+
+	return 0;
+}
+
+/**
+ * ibmvmc_send_add_buffer_resp - Add Buffer Response
+ *
+ * @adapter:	crq_server_adapter struct
+ * @status:	Status field
+ * @hmc_session: HMC Session field
+ * @hmc_index:	HMC Index field
+ * @buffer_id:	Buffer Id field
+ *
+ * This command is sent by the management partition to the hypervisor in
+ * response to the Add Buffer message. The Status field indicates the result of
+ * the command.
+ *
+ * Return:
+ *	0 - Success
+ */
+static int ibmvmc_send_add_buffer_resp(struct crq_server_adapter *adapter,
+				       u8 status, u8 hmc_session,
+				       u8 hmc_index, u16 buffer_id)
+{
+	struct ibmvmc_crq_msg crq_msg;
+	__be64 *crq_as_u64 = (__be64 *)&crq_msg;
+
+	dev_dbg(adapter->dev, "CRQ send: add_buffer_resp\n");
+	crq_msg.valid = 0x80;
+	crq_msg.type = VMC_MSG_ADD_BUF_RESP;
+	crq_msg.status = status;
+	crq_msg.var1.rsvd = 0;
+	crq_msg.hmc_session = hmc_session;
+	crq_msg.hmc_index = hmc_index;
+	crq_msg.var2.buffer_id = cpu_to_be16(buffer_id);
+	crq_msg.rsvd = 0;
+	crq_msg.var3.rsvd = 0;
+
+	ibmvmc_send_crq(adapter, be64_to_cpu(crq_as_u64[0]),
+			be64_to_cpu(crq_as_u64[1]));
+
+	return 0;
+}
+
+/**
+ * ibmvmc_send_rem_buffer_resp - Remove Buffer Response
+ *
+ * @adapter:	crq_server_adapter struct
+ * @status:	Status field
+ * @hmc_session: HMC Session field
+ * @hmc_index:	HMC Index field
+ * @buffer_id:	Buffer Id field
+ *
+ * This command is sent by the management partition to the hypervisor in
+ * response to the Remove Buffer message. The Buffer ID field indicates
+ * which buffer the management partition selected to remove. The Status
+ * field indicates the result of the command.
+ *
+ * Return:
+ *	0 - Success
+ */
+static int ibmvmc_send_rem_buffer_resp(struct crq_server_adapter *adapter,
+				       u8 status, u8 hmc_session,
+				       u8 hmc_index, u16 buffer_id)
+{
+	struct ibmvmc_crq_msg crq_msg;
+	__be64 *crq_as_u64 = (__be64 *)&crq_msg;
+
+	dev_dbg(adapter->dev, "CRQ send: rem_buffer_resp\n");
+	crq_msg.valid = 0x80;
+	crq_msg.type = VMC_MSG_REM_BUF_RESP;
+	crq_msg.status = status;
+	crq_msg.var1.rsvd = 0;
+	crq_msg.hmc_session = hmc_session;
+	crq_msg.hmc_index = hmc_index;
+	crq_msg.var2.buffer_id = cpu_to_be16(buffer_id);
+	crq_msg.rsvd = 0;
+	crq_msg.var3.rsvd = 0;
+
+	ibmvmc_send_crq(adapter, be64_to_cpu(crq_as_u64[0]),
+			be64_to_cpu(crq_as_u64[1]));
+
+	return 0;
+}
+
+/**
+ * ibmvmc_send_msg - Signal Message
+ *
+ * @adapter:	crq_server_adapter struct
+ * @buffer:	ibmvmc_buffer struct
+ * @hmc:	ibmvmc_hmc struct
+ * @msg_length:	message length field
+ *
+ * This command is sent between the management partition and the hypervisor
+ * in order to signal the arrival of an HMC protocol message. The command
+ * can be sent by both the management partition and the hypervisor. It is
+ * used for all traffic between the management application and the hypervisor,
+ * regardless of who initiated the communication.
+ *
+ * There is no response to this message.
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static int ibmvmc_send_msg(struct crq_server_adapter *adapter,
+			   struct ibmvmc_buffer *buffer,
+			   struct ibmvmc_hmc *hmc, int msg_len)
+{
+	struct ibmvmc_crq_msg crq_msg;
+	__be64 *crq_as_u64 = (__be64 *)&crq_msg;
+	int rc = 0;
+
+	dev_dbg(adapter->dev, "CRQ send: rdma to HV\n");
+	rc = h_copy_rdma(msg_len,
+			 adapter->liobn,
+			 buffer->dma_addr_local,
+			 adapter->riobn,
+			 buffer->dma_addr_remote);
+	if (rc) {
+		dev_err(adapter->dev, "Error in send_msg, h_copy_rdma rc 0x%x\n",
+			rc);
+		return rc;
+	}
+
+	crq_msg.valid = 0x80;
+	crq_msg.type = VMC_MSG_SIGNAL;
+	crq_msg.status = 0;
+	crq_msg.var1.rsvd = 0;
+	crq_msg.hmc_session = hmc->session;
+	crq_msg.hmc_index = hmc->index;
+	crq_msg.var2.buffer_id = cpu_to_be16(buffer->id);
+	crq_msg.var3.msg_len = cpu_to_be32(msg_len);
+	dev_dbg(adapter->dev, "CRQ send: msg to HV 0x%llx 0x%llx\n",
+		be64_to_cpu(crq_as_u64[0]), be64_to_cpu(crq_as_u64[1]));
+
+	buffer->owner = VMC_BUF_OWNER_HV;
+	ibmvmc_send_crq(adapter, be64_to_cpu(crq_as_u64[0]),
+			be64_to_cpu(crq_as_u64[1]));
+
+	return rc;
+}
+
+/**
+ * ibmvmc_open - Open Session
+ *
+ * @inode:	inode struct
+ * @file:	file struct
+ *
+ * Return:
+ *	0 - Success
+ */
+static int ibmvmc_open(struct inode *inode, struct file *file)
+{
+	struct ibmvmc_file_session *session;
+	int rc = 0;
+
+	pr_debug("%s: inode = 0x%lx, file = 0x%lx, state = 0x%x\n", __func__,
+		 (unsigned long)inode, (unsigned long)file,
+		 ibmvmc.state);
+
+	session = kzalloc(sizeof(*session), GFP_KERNEL);
+	session->file = file;
+	file->private_data = session;
+
+	return rc;
+}
+
+/**
+ * ibmvmc_close - Close Session
+ *
+ * @inode:	inode struct
+ * @file:	file struct
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static int ibmvmc_close(struct inode *inode, struct file *file)
+{
+	struct ibmvmc_file_session *session;
+	struct ibmvmc_hmc *hmc;
+	int rc = 0;
+	unsigned long flags;
+
+	pr_debug("%s: file = 0x%lx, state = 0x%x\n", __func__,
+		 (unsigned long)file, ibmvmc.state);
+
+	session = file->private_data;
+	if (!session)
+		return -EIO;
+
+	hmc = session->hmc;
+	if (hmc) {
+		if (!hmc->adapter)
+			return -EIO;
+
+		if (ibmvmc.state == ibmvmc_state_failed) {
+			dev_warn(hmc->adapter->dev, "close: state_failed\n");
+			return -EIO;
+		}
+
+		spin_lock_irqsave(&hmc->lock, flags);
+		if (hmc->state >= ibmhmc_state_opening) {
+			rc = ibmvmc_send_close(hmc);
+			if (rc)
+				dev_warn(hmc->adapter->dev, "close: send_close failed.\n");
+		}
+		spin_unlock_irqrestore(&hmc->lock, flags);
+	}
+
+	kzfree(session);
+
+	return rc;
+}
+
+/**
+ * ibmvmc_read - Read
+ *
+ * @file:	file struct
+ * @buf:	Character buffer
+ * @nbytes:	Size in bytes
+ * @ppos:	Offset
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static ssize_t ibmvmc_read(struct file *file, char *buf, size_t nbytes,
+			   loff_t *ppos)
+{
+	struct ibmvmc_file_session *session;
+	struct ibmvmc_hmc *hmc;
+	struct crq_server_adapter *adapter;
+	struct ibmvmc_buffer *buffer;
+	ssize_t n;
+	ssize_t retval = 0;
+	unsigned long flags;
+	DEFINE_WAIT(wait);
+
+	pr_debug("ibmvmc: read: file = 0x%lx, buf = 0x%lx, nbytes = 0x%lx\n",
+		 (unsigned long)file, (unsigned long)buf,
+		 (unsigned long)nbytes);
+
+	if (nbytes == 0)
+		return 0;
+
+	if (nbytes > ibmvmc.max_mtu) {
+		pr_warn("ibmvmc: read: nbytes invalid 0x%x\n",
+			(unsigned int)nbytes);
+		return -EINVAL;
+	}
+
+	session = file->private_data;
+	if (!session) {
+		pr_warn("ibmvmc: read: no session\n");
+		return -EIO;
+	}
+
+	hmc = session->hmc;
+	if (!hmc) {
+		pr_warn("ibmvmc: read: no hmc\n");
+		return -EIO;
+	}
+
+	adapter = hmc->adapter;
+	if (!adapter) {
+		pr_warn("ibmvmc: read: no adapter\n");
+		return -EIO;
+	}
+
+	do {
+		prepare_to_wait(&ibmvmc_read_wait, &wait, TASK_INTERRUPTIBLE);
+
+		spin_lock_irqsave(&hmc->lock, flags);
+		if (hmc->queue_tail != hmc->queue_head)
+			/* Data is available */
+			break;
+
+		spin_unlock_irqrestore(&hmc->lock, flags);
+
+		if (!session->valid) {
+			retval = -EBADFD;
+			goto out;
+		}
+		if (file->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto out;
+		}
+
+		schedule();
+
+		if (signal_pending(current)) {
+			retval = -ERESTARTSYS;
+			goto out;
+		}
+	} while (1);
+
+	buffer = &(hmc->buffer[hmc->queue_outbound_msgs[hmc->queue_tail]]);
+	hmc->queue_tail++;
+	if (hmc->queue_tail == ibmvmc_max_buf_pool_size)
+		hmc->queue_tail = 0;
+	spin_unlock_irqrestore(&hmc->lock, flags);
+
+	nbytes = min_t(size_t, nbytes, buffer->msg_len);
+	n = copy_to_user((void *)buf, buffer->real_addr_local, nbytes);
+	dev_dbg(adapter->dev, "read: copy to user nbytes = 0x%lx.\n", nbytes);
+	ibmvmc_free_hmc_buffer(hmc, buffer);
+	retval = nbytes;
+
+	if (n) {
+		dev_warn(adapter->dev, "read: copy to user failed.\n");
+		retval = -EFAULT;
+	}
+
+ out:
+	finish_wait(&ibmvmc_read_wait, &wait);
+	dev_dbg(adapter->dev, "read: out %ld\n", retval);
+	return retval;
+}
+
+/**
+ * ibmvmc_poll - Poll
+ *
+ * @file:	file struct
+ * @wait:	Poll Table
+ *
+ * Return:
+ *	poll.h return values
+ */
+static unsigned int ibmvmc_poll(struct file *file, poll_table *wait)
+{
+	struct ibmvmc_file_session *session;
+	struct ibmvmc_hmc *hmc;
+	unsigned int mask = 0;
+
+	session = file->private_data;
+	if (!session)
+		return 0;
+
+	hmc = session->hmc;
+	if (!hmc)
+		return 0;
+
+	poll_wait(file, &ibmvmc_read_wait, wait);
+
+	if (hmc->queue_head != hmc->queue_tail)
+		mask |= POLLIN | POLLRDNORM;
+
+	return mask;
+}
+
+/**
+ * ibmvmc_write - Write
+ *
+ * @file:	file struct
+ * @buf:	Character buffer
+ * @count:	Count field
+ * @ppos:	Offset
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static ssize_t ibmvmc_write(struct file *file, const char *buffer,
+			    size_t count, loff_t *ppos)
+{
+	struct ibmvmc_buffer *vmc_buffer;
+	struct ibmvmc_file_session *session;
+	struct crq_server_adapter *adapter;
+	struct ibmvmc_hmc *hmc;
+	unsigned char *buf;
+	unsigned long flags;
+	size_t bytes;
+	const char *p = buffer;
+	size_t c = count;
+	int ret = 0;
+
+	session = file->private_data;
+	if (!session)
+		return -EIO;
+
+	hmc = session->hmc;
+	if (!hmc)
+		return -EIO;
+
+	spin_lock_irqsave(&hmc->lock, flags);
+	if (hmc->state == ibmhmc_state_free) {
+		/* HMC connection is not valid (possibly was reset under us). */
+		ret = -EIO;
+		goto out;
+	}
+
+	adapter = hmc->adapter;
+	if (!adapter) {
+		ret = -EIO;
+		goto out;
+	}
+
+	if (count > ibmvmc.max_mtu) {
+		dev_warn(adapter->dev, "invalid buffer size 0x%lx\n",
+			 (unsigned long)count);
+		ret = -EIO;
+		goto out;
+	}
+
+	/* Waiting for the open resp message to the ioctl(1) - retry */
+	if (hmc->state == ibmhmc_state_opening) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	/* Make sure the ioctl() was called & the open msg sent, and that
+	 * the HMC connection has not failed.
+	 */
+	if (hmc->state != ibmhmc_state_ready) {
+		ret = -EIO;
+		goto out;
+	}
+
+	vmc_buffer = ibmvmc_get_valid_hmc_buffer(hmc->index);
+	if (!vmc_buffer) {
+		/* No buffer available for the msg send, or we have not yet
+		 * completed the open/open_resp sequence.  Retry until this is
+		 * complete.
+		 */
+		ret = -EBUSY;
+		goto out;
+	}
+	if (!vmc_buffer->real_addr_local) {
+		dev_err(adapter->dev, "no buffer storage assigned\n");
+		ret = -EIO;
+		goto out;
+	}
+	buf = vmc_buffer->real_addr_local;
+
+	while (c > 0) {
+		bytes = min_t(size_t, c, vmc_buffer->size);
+
+		bytes -= copy_from_user(buf, p, bytes);
+		if (!bytes) {
+			ret = -EFAULT;
+			goto out;
+		}
+		c -= bytes;
+		p += bytes;
+	}
+	if (p == buffer)
+		goto out;
+
+	file->f_path.dentry->d_inode->i_mtime = current_time(file_inode(file));
+	mark_inode_dirty(file->f_path.dentry->d_inode);
+
+	dev_dbg(adapter->dev, "write: file = 0x%lx, count = 0x%lx\n",
+		(unsigned long)file, (unsigned long)count);
+
+	ibmvmc_send_msg(adapter, vmc_buffer, hmc, count);
+	ret = p - buffer;
+ out:
+	spin_unlock_irqrestore(&hmc->lock, flags);
+	return (ssize_t)(ret);
+}
+
+/**
+ * ibmvmc_setup_hmc - Setup the HMC
+ *
+ * @session:	ibmvmc_file_session struct
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static long ibmvmc_setup_hmc(struct ibmvmc_file_session *session)
+{
+	struct ibmvmc_hmc *hmc;
+	unsigned int valid, free, index;
+
+	if (ibmvmc.state == ibmvmc_state_failed) {
+		pr_warn("ibmvmc: Reserve HMC: state_failed\n");
+		return -EIO;
+	}
+
+	if (ibmvmc.state < ibmvmc_state_ready) {
+		pr_warn("ibmvmc: Reserve HMC: not state_ready\n");
+		return -EAGAIN;
+	}
+
+	/* Device is busy until capabilities have been exchanged and we
+	 * have a generic buffer for each possible HMC connection.
+	 */
+	for (index = 0; index <= ibmvmc.max_hmc_index; index++) {
+		valid = 0;
+		ibmvmc_count_hmc_buffers(index, &valid, &free);
+		if (valid == 0) {
+			pr_warn("ibmvmc: buffers not ready for index %d\n",
+				index);
+			return -ENOBUFS;
+		}
+	}
+
+	/* Get an hmc object, and transition to ibmhmc_state_initial */
+	hmc = ibmvmc_get_free_hmc();
+	if (!hmc) {
+		pr_warn("%s: free hmc not found\n", __func__);
+		return -EBUSY;
+	}
+
+	hmc->session = hmc->session + 1;
+	if (hmc->session == 0xff)
+		hmc->session = 1;
+
+	session->hmc = hmc;
+	hmc->adapter = &ibmvmc_adapter;
+	hmc->file_session = session;
+	session->valid = 1;
+
+	return 0;
+}
+
+/**
+ * ibmvmc_ioctl_sethmcid - IOCTL Set HMC ID
+ *
+ * @session:	ibmvmc_file_session struct
+ * @new_hmc_id:	HMC id field
+ *
+ * IOCTL command to setup the hmc id
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static long ibmvmc_ioctl_sethmcid(struct ibmvmc_file_session *session,
+				  unsigned char __user *new_hmc_id)
+{
+	struct ibmvmc_hmc *hmc;
+	struct ibmvmc_buffer *buffer;
+	size_t bytes;
+	char print_buffer[HMC_ID_LEN + 1];
+	unsigned long flags;
+	long rc = 0;
+
+	/* Reserve HMC session */
+	hmc = session->hmc;
+	if (!hmc) {
+		rc = ibmvmc_setup_hmc(session);
+		if (rc)
+			return rc;
+
+		hmc = session->hmc;
+		if (!hmc) {
+			pr_err("ibmvmc: setup_hmc success but no hmc\n");
+			return -EIO;
+		}
+	}
+
+	if (hmc->state != ibmhmc_state_initial) {
+		pr_warn("ibmvmc: sethmcid: invalid state to send open 0x%x\n",
+			hmc->state);
+		return -EIO;
+	}
+
+	bytes = copy_from_user(hmc->hmc_id, new_hmc_id, HMC_ID_LEN);
+	if (bytes)
+		return -EFAULT;
+
+	/* Send Open Session command */
+	spin_lock_irqsave(&hmc->lock, flags);
+	buffer = ibmvmc_get_valid_hmc_buffer(hmc->index);
+	spin_unlock_irqrestore(&hmc->lock, flags);
+
+	if (!buffer || !buffer->real_addr_local) {
+		pr_warn("ibmvmc: sethmcid: no buffer available\n");
+		return -EIO;
+	}
+
+	/* Make sure buffer is NULL terminated before trying to print it */
+	memset(print_buffer, 0, HMC_ID_LEN + 1);
+	strncpy(print_buffer, hmc->hmc_id, HMC_ID_LEN);
+	pr_info("ibmvmc: sethmcid: Set HMC ID: \"%s\"\n", print_buffer);
+
+	memcpy(buffer->real_addr_local, hmc->hmc_id, HMC_ID_LEN);
+	/* RDMA over ID, send open msg, change state to ibmhmc_state_opening */
+	rc = ibmvmc_send_open(buffer, hmc);
+
+	return rc;
+}
+
+/**
+ * ibmvmc_ioctl_query - IOCTL Query
+ *
+ * @session:	ibmvmc_file_session struct
+ * @ret_struct:	ibmvmc_query_struct
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static long ibmvmc_ioctl_query(struct ibmvmc_file_session *session,
+			       struct ibmvmc_query_struct __user *ret_struct)
+{
+	struct ibmvmc_query_struct query_struct;
+	size_t bytes;
+
+	memset(&query_struct, 0, sizeof(query_struct));
+	query_struct.have_vmc = (ibmvmc.state > ibmvmc_state_initial);
+	query_struct.state = ibmvmc.state;
+	query_struct.vmc_drc_index = ibmvmc.vmc_drc_index;
+
+	bytes = copy_to_user(ret_struct, &query_struct,
+			     sizeof(query_struct));
+	if (bytes)
+		return -EFAULT;
+
+	return 0;
+}
+
+/**
+ * ibmvmc_ioctl_requestvmc - IOCTL Request VMC
+ *
+ * @session:	ibmvmc_file_session struct
+ * @ret_vmc_index:	VMC Index
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static long ibmvmc_ioctl_requestvmc(struct ibmvmc_file_session *session,
+				    u32 __user *ret_vmc_index)
+{
+	/* TODO: (adreznec) Add locking to control multiple process access */
+	size_t bytes;
+	long rc;
+	u32 vmc_drc_index;
+
+	/* Call to request the VMC device from phyp*/
+	rc = h_request_vmc(&vmc_drc_index);
+	pr_debug("ibmvmc: requestvmc: H_REQUEST_VMC rc = 0x%lx\n", rc);
+
+	if (rc == H_SUCCESS) {
+		rc = 0;
+	} else if (rc == H_FUNCTION) {
+		pr_err("ibmvmc: requestvmc: h_request_vmc not supported\n");
+		return -EPERM;
+	} else if (rc == H_AUTHORITY) {
+		pr_err("ibmvmc: requestvmc: hypervisor denied vmc request\n");
+		return -EPERM;
+	} else if (rc == H_HARDWARE) {
+		pr_err("ibmvmc: requestvmc: hypervisor hardware fault\n");
+		return -EIO;
+	} else if (rc == H_RESOURCE) {
+		pr_err("ibmvmc: requestvmc: vmc resource unavailable\n");
+		return -ENODEV;
+	} else if (rc == H_NOT_AVAILABLE) {
+		pr_err("ibmvmc: requestvmc: system cannot be vmc managed\n");
+		return -EPERM;
+	} else if (rc == H_PARAMETER) {
+		pr_err("ibmvmc: requestvmc: invalid parameter\n");
+		return -EINVAL;
+	}
+
+	/* Success, set the vmc index in global struct */
+	ibmvmc.vmc_drc_index = vmc_drc_index;
+
+	bytes = copy_to_user(ret_vmc_index, &vmc_drc_index,
+			     sizeof(*ret_vmc_index));
+	if (bytes) {
+		pr_warn("ibmvmc: requestvmc: copy to user failed.\n");
+		return -EFAULT;
+	}
+	return rc;
+}
+
+/**
+ * ibmvmc_ioctl - IOCTL
+ *
+ * @session:	ibmvmc_file_session struct
+ * @cmd:	cmd field
+ * @arg:	Argument field
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static long ibmvmc_ioctl(struct file *file,
+			 unsigned int cmd, unsigned long arg)
+{
+	struct ibmvmc_file_session *session = file->private_data;
+
+	pr_debug("ibmvmc: ioctl file=0x%lx, cmd=0x%x, arg=0x%lx, ses=0x%lx\n",
+		 (unsigned long)file, cmd, arg,
+		 (unsigned long)session);
+
+	if (!session) {
+		pr_warn("ibmvmc: ioctl: no session\n");
+		return -EIO;
+	}
+
+	switch (cmd) {
+	case VMC_IOCTL_SETHMCID:
+		return ibmvmc_ioctl_sethmcid(session,
+			(unsigned char __user *)arg);
+	case VMC_IOCTL_QUERY:
+		return ibmvmc_ioctl_query(session,
+			(struct ibmvmc_query_struct __user *)arg);
+	case VMC_IOCTL_REQUESTVMC:
+		return ibmvmc_ioctl_requestvmc(session,
+			(unsigned int __user *)arg);
+	default:
+		pr_warn("ibmvmc: unknown ioctl 0x%x\n", cmd);
+		return -EINVAL;
+	}
+}
+
+static const struct file_operations ibmvmc_fops = {
+	.owner		= THIS_MODULE,
+	.read		= ibmvmc_read,
+	.write		= ibmvmc_write,
+	.poll		= ibmvmc_poll,
+	.unlocked_ioctl	= ibmvmc_ioctl,
+	.open           = ibmvmc_open,
+	.release        = ibmvmc_close,
+};
+
+/**
+ * ibmvmc_add_buffer - Add Buffer
+ *
+ * @adapter: crq_server_adapter struct
+ * @crq:	ibmvmc_crq_msg struct
+ *
+ * This message transfers a buffer from hypervisor ownership to management
+ * partition ownership. The LIOBA is obtained from the virtual TCE table
+ * associated with the hypervisor side of the VMC device, and points to a
+ * buffer of size MTU (as established in the capabilities exchange).
+ *
+ * Typical flow for ading buffers:
+ * 1. A new management application connection is opened by the management
+ *	partition.
+ * 2. The hypervisor assigns new buffers for the traffic associated with
+ *	that connection.
+ * 3. The hypervisor sends VMC Add Buffer messages to the management
+ *	partition, informing it of the new buffers.
+ * 4. The hypervisor sends an HMC protocol message (to the management
+ *	application) notifying it of the new buffers. This informs the
+ *	application that it has buffers available for sending HMC
+ *	commands.
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static int ibmvmc_add_buffer(struct crq_server_adapter *adapter,
+			     struct ibmvmc_crq_msg *crq)
+{
+	struct ibmvmc_buffer *buffer;
+	u8 hmc_index;
+	u8 hmc_session;
+	u16 buffer_id;
+	unsigned long flags;
+	int rc = 0;
+
+	if (!crq)
+		return -1;
+
+	hmc_session = crq->hmc_session;
+	hmc_index = crq->hmc_index;
+	buffer_id = be16_to_cpu(crq->var2.buffer_id);
+
+	if (hmc_index > ibmvmc.max_hmc_index) {
+		dev_err(adapter->dev, "add_buffer: invalid hmc_index = 0x%x\n",
+			hmc_index);
+		ibmvmc_send_add_buffer_resp(adapter, VMC_MSG_INVALID_HMC_INDEX,
+					    hmc_session, hmc_index, buffer_id);
+		return -1;
+	}
+
+	if (buffer_id >= ibmvmc.max_buffer_pool_size) {
+		dev_err(adapter->dev, "add_buffer: invalid buffer_id = 0x%x\n",
+			buffer_id);
+		ibmvmc_send_add_buffer_resp(adapter, VMC_MSG_INVALID_BUFFER_ID,
+					    hmc_session, hmc_index, buffer_id);
+		return -1;
+	}
+
+	spin_lock_irqsave(&hmcs[hmc_index].lock, flags);
+	buffer = &hmcs[hmc_index].buffer[buffer_id];
+
+	if (buffer->real_addr_local || buffer->dma_addr_local) {
+		dev_warn(adapter->dev, "add_buffer: already allocated id = 0x%lx\n",
+			 (unsigned long)buffer_id);
+		spin_unlock_irqrestore(&hmcs[hmc_index].lock, flags);
+		ibmvmc_send_add_buffer_resp(adapter, VMC_MSG_INVALID_BUFFER_ID,
+					    hmc_session, hmc_index, buffer_id);
+		return -1;
+	}
+
+	buffer->real_addr_local = alloc_dma_buffer(to_vio_dev(adapter->dev),
+						   ibmvmc.max_mtu,
+						   &buffer->dma_addr_local);
+
+	if (!buffer->real_addr_local) {
+		dev_err(adapter->dev, "add_buffer: alloc_dma_buffer failed.\n");
+		spin_unlock_irqrestore(&hmcs[hmc_index].lock, flags);
+		ibmvmc_send_add_buffer_resp(adapter, VMC_MSG_INTERFACE_FAILURE,
+					    hmc_session, hmc_index, buffer_id);
+		return -1;
+	}
+
+	buffer->dma_addr_remote = be32_to_cpu(crq->var3.lioba);
+	buffer->size = ibmvmc.max_mtu;
+	buffer->owner = crq->var1.owner;
+	buffer->free = 1;
+	/* Must ensure valid==1 is observable only after all other fields are */
+	dma_wmb();
+	buffer->valid = 1;
+	buffer->id = buffer_id;
+
+	dev_dbg(adapter->dev, "add_buffer: successfully added a buffer:\n");
+	dev_dbg(adapter->dev, "   index: %d, session: %d, buffer: 0x%x, owner: %d\n",
+		hmc_index, hmc_session, buffer_id, buffer->owner);
+	dev_dbg(adapter->dev, "   local: 0x%x, remote: 0x%x\n",
+		(u32)buffer->dma_addr_local,
+		(u32)buffer->dma_addr_remote);
+	spin_unlock_irqrestore(&hmcs[hmc_index].lock, flags);
+
+	ibmvmc_send_add_buffer_resp(adapter, VMC_MSG_SUCCESS, hmc_session,
+				    hmc_index, buffer_id);
+
+	return rc;
+}
+
+/**
+ * ibmvmc_rem_buffer - Remove Buffer
+ *
+ * @adapter: crq_server_adapter struct
+ * @crq:	ibmvmc_crq_msg struct
+ *
+ * This message requests an HMC buffer to be transferred from management
+ * partition ownership to hypervisor ownership. The management partition may
+ * not be able to satisfy the request at a particular point in time if all its
+ * buffers are in use. The management partition requires a depth of at least
+ * one inbound buffer to allow management application commands to flow to the
+ * hypervisor. It is, therefore, an interface error for the hypervisor to
+ * attempt to remove the management partition's last buffer.
+ *
+ * The hypervisor is expected to manage buffer usage with the management
+ * application directly and inform the management partition when buffers may be
+ * removed. The typical flow for removing buffers:
+ *
+ * 1. The management application no longer needs a communication path to a
+ *	particular hypervisor function. That function is closed.
+ * 2. The hypervisor and the management application quiesce all traffic to that
+ *	function. The hypervisor requests a reduction in buffer pool size.
+ * 3. The management application acknowledges the reduction in buffer pool size.
+ * 4. The hypervisor sends a Remove Buffer message to the management partition,
+ *	informing it of the reduction in buffers.
+ * 5. The management partition verifies it can remove the buffer. This is
+ *	possible if buffers have been quiesced.
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+/*
+ * The hypervisor requested that we pick an unused buffer, and return it.
+ * Before sending the buffer back, we free any storage associated with the
+ * buffer.
+ */
+static int ibmvmc_rem_buffer(struct crq_server_adapter *adapter,
+			     struct ibmvmc_crq_msg *crq)
+{
+	struct ibmvmc_buffer *buffer;
+	u8 hmc_index;
+	u8 hmc_session;
+	u16 buffer_id = 0;
+	unsigned long flags;
+	int rc = 0;
+
+	if (!crq)
+		return -1;
+
+	hmc_session = crq->hmc_session;
+	hmc_index = crq->hmc_index;
+
+	if (hmc_index > ibmvmc.max_hmc_index) {
+		dev_warn(adapter->dev, "rem_buffer: invalid hmc_index = 0x%x\n",
+			 hmc_index);
+		ibmvmc_send_rem_buffer_resp(adapter, VMC_MSG_INVALID_HMC_INDEX,
+					    hmc_session, hmc_index, buffer_id);
+		return -1;
+	}
+
+	spin_lock_irqsave(&hmcs[hmc_index].lock, flags);
+	buffer = ibmvmc_get_free_hmc_buffer(adapter, hmc_index);
+	if (!buffer) {
+		dev_info(adapter->dev, "rem_buffer: no buffer to remove\n");
+		spin_unlock_irqrestore(&hmcs[hmc_index].lock, flags);
+		ibmvmc_send_rem_buffer_resp(adapter, VMC_MSG_NO_BUFFER,
+					    hmc_session, hmc_index,
+					    VMC_INVALID_BUFFER_ID);
+		return -1;
+	}
+
+	buffer_id = buffer->id;
+
+	if (buffer->valid)
+		free_dma_buffer(to_vio_dev(adapter->dev),
+				ibmvmc.max_mtu,
+				buffer->real_addr_local,
+				buffer->dma_addr_local);
+
+	memset(buffer, 0, sizeof(struct ibmvmc_buffer));
+	spin_unlock_irqrestore(&hmcs[hmc_index].lock, flags);
+
+	dev_dbg(adapter->dev, "rem_buffer: removed buffer 0x%x.\n", buffer_id);
+	ibmvmc_send_rem_buffer_resp(adapter, VMC_MSG_SUCCESS, hmc_session,
+				    hmc_index, buffer_id);
+
+	return rc;
+}
+
+static int ibmvmc_recv_msg(struct crq_server_adapter *adapter,
+			   struct ibmvmc_crq_msg *crq)
+{
+	struct ibmvmc_buffer *buffer;
+	struct ibmvmc_hmc *hmc;
+	unsigned long msg_len;
+	u8 hmc_index;
+	u8 hmc_session;
+	u16 buffer_id;
+	unsigned long flags;
+	int rc = 0;
+
+	if (!crq)
+		return -1;
+
+	/* Hypervisor writes CRQs directly into our memory in big endian */
+	dev_dbg(adapter->dev, "Recv_msg: msg from HV 0x%016llx 0x%016llx\n",
+		be64_to_cpu(*((unsigned long *)crq)),
+		be64_to_cpu(*(((unsigned long *)crq) + 1)));
+
+	hmc_session = crq->hmc_session;
+	hmc_index = crq->hmc_index;
+	buffer_id = be16_to_cpu(crq->var2.buffer_id);
+	msg_len = be32_to_cpu(crq->var3.msg_len);
+
+	if (hmc_index > ibmvmc.max_hmc_index) {
+		dev_err(adapter->dev, "Recv_msg: invalid hmc_index = 0x%x\n",
+			hmc_index);
+		ibmvmc_send_add_buffer_resp(adapter, VMC_MSG_INVALID_HMC_INDEX,
+					    hmc_session, hmc_index, buffer_id);
+		return -1;
+	}
+
+	if (buffer_id >= ibmvmc.max_buffer_pool_size) {
+		dev_err(adapter->dev, "Recv_msg: invalid buffer_id = 0x%x\n",
+			buffer_id);
+		ibmvmc_send_add_buffer_resp(adapter, VMC_MSG_INVALID_BUFFER_ID,
+					    hmc_session, hmc_index, buffer_id);
+		return -1;
+	}
+
+	hmc = &hmcs[hmc_index];
+	spin_lock_irqsave(&hmc->lock, flags);
+
+	if (hmc->state == ibmhmc_state_free) {
+		dev_err(adapter->dev, "Recv_msg: invalid hmc state = 0x%x\n",
+			hmc->state);
+		/* HMC connection is not valid (possibly was reset under us). */
+		spin_unlock_irqrestore(&hmc->lock, flags);
+		return -1;
+	}
+
+	buffer = &hmc->buffer[buffer_id];
+
+	if (buffer->valid == 0 || buffer->owner == VMC_BUF_OWNER_ALPHA) {
+		dev_err(adapter->dev, "Recv_msg: not valid, or not HV.  0x%x 0x%x\n",
+			buffer->valid, buffer->owner);
+		spin_unlock_irqrestore(&hmc->lock, flags);
+		return -1;
+	}
+
+	/* RDMA the data into the partition. */
+	rc = h_copy_rdma(msg_len,
+			 adapter->riobn,
+			 buffer->dma_addr_remote,
+			 adapter->liobn,
+			 buffer->dma_addr_local);
+
+	dev_dbg(adapter->dev, "Recv_msg: msg_len = 0x%x, buffer_id = 0x%x, queue_head = 0x%x, hmc_idx = 0x%x\n",
+		(unsigned int)msg_len, (unsigned int)buffer_id,
+		(unsigned int)hmc->queue_head, (unsigned int)hmc_index);
+	buffer->msg_len = msg_len;
+	buffer->free = 0;
+	buffer->owner = VMC_BUF_OWNER_ALPHA;
+
+	if (rc) {
+		dev_err(adapter->dev, "Failure in recv_msg: h_copy_rdma = 0x%x\n",
+			rc);
+		spin_unlock_irqrestore(&hmc->lock, flags);
+		return -1;
+	}
+
+	/* Must be locked because read operates on the same data */
+	hmc->queue_outbound_msgs[hmc->queue_head] = buffer_id;
+	hmc->queue_head++;
+	if (hmc->queue_head == ibmvmc_max_buf_pool_size)
+		hmc->queue_head = 0;
+
+	if (hmc->queue_head == hmc->queue_tail)
+		dev_err(adapter->dev, "outbound buffer queue wrapped.\n");
+
+	spin_unlock_irqrestore(&hmc->lock, flags);
+
+	wake_up_interruptible(&ibmvmc_read_wait);
+
+	return 0;
+}
+
+/**
+ * ibmvmc_process_capabilities - Process Capabilities
+ *
+ * @adapter:	crq_server_adapter struct
+ * @crqp:	ibmvmc_crq_msg struct
+ *
+ */
+static void ibmvmc_process_capabilities(struct crq_server_adapter *adapter,
+					struct ibmvmc_crq_msg *crqp)
+{
+	struct ibmvmc_admin_crq_msg *crq = (struct ibmvmc_admin_crq_msg *)crqp;
+
+	if ((be16_to_cpu(crq->version) >> 8) !=
+			(IBMVMC_PROTOCOL_VERSION >> 8)) {
+		dev_err(adapter->dev, "init failed, incompatible versions 0x%x 0x%x\n",
+			be16_to_cpu(crq->version),
+			IBMVMC_PROTOCOL_VERSION);
+		ibmvmc.state = ibmvmc_state_failed;
+		return;
+	}
+
+	ibmvmc.max_mtu = min_t(u32, ibmvmc_max_mtu, be32_to_cpu(crq->max_mtu));
+	ibmvmc.max_buffer_pool_size = min_t(u16, ibmvmc_max_buf_pool_size,
+					    be16_to_cpu(crq->pool_size));
+	ibmvmc.max_hmc_index = min_t(u8, ibmvmc_max_hmcs, crq->max_hmc) - 1;
+	ibmvmc.state = ibmvmc_state_ready;
+
+	dev_info(adapter->dev, "Capabilities: mtu=0x%x, pool_size=0x%x, max_hmc=0x%x\n",
+		 ibmvmc.max_mtu, ibmvmc.max_buffer_pool_size,
+		 ibmvmc.max_hmc_index);
+}
+
+/**
+ * ibmvmc_validate_hmc_session - Validate HMC Session
+ *
+ * @adapter:	crq_server_adapter struct
+ * @crq:	ibmvmc_crq_msg struct
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static int ibmvmc_validate_hmc_session(struct crq_server_adapter *adapter,
+				       struct ibmvmc_crq_msg *crq)
+{
+	unsigned char hmc_index;
+
+	hmc_index = crq->hmc_index;
+
+	if (crq->hmc_session == 0)
+		return 0;
+
+	if (hmc_index > ibmvmc.max_hmc_index)
+		return -1;
+
+	if (hmcs[hmc_index].session != crq->hmc_session) {
+		dev_warn(adapter->dev, "Drop, bad session: expected 0x%x, recv 0x%x\n",
+			 hmcs[hmc_index].session, crq->hmc_session);
+		return -1;
+	}
+
+	return 0;
+}
+
+/**
+ * ibmvmc_reset - Reset
+ *
+ * @adapter:	crq_server_adapter struct
+ * @xport_event:	export_event field
+ *
+ * Closes all HMC sessions and conditionally schedules a CRQ reset.
+ * @xport_event: If true, the partner closed their CRQ; we don't need to reset.
+ *               If false, we need to schedule a CRQ reset.
+ */
+static void ibmvmc_reset(struct crq_server_adapter *adapter, bool xport_event)
+{
+	int i;
+
+	if (ibmvmc.state != ibmvmc_state_sched_reset) {
+		dev_info(adapter->dev, "*** Reset to initial state.\n");
+		for (i = 0; i < ibmvmc_max_hmcs; i++)
+			ibmvmc_return_hmc(&hmcs[i], xport_event);
+
+		if (xport_event) {
+			/* CRQ was closed by the partner.  We don't need to do
+			 * anything except set ourself to the correct state to
+			 * handle init msgs.
+			 */
+			ibmvmc.state = ibmvmc_state_crqinit;
+		} else {
+			/* The partner did not close their CRQ - instead, we're
+			 * closing the CRQ on our end. Need to schedule this
+			 * for process context, because CRQ reset may require a
+			 * sleep.
+			 *
+			 * Setting ibmvmc.state here immediately prevents
+			 * ibmvmc_open from completing until the reset
+			 * completes in process context.
+			 */
+			ibmvmc.state = ibmvmc_state_sched_reset;
+			dev_dbg(adapter->dev, "Device reset scheduled");
+			wake_up_interruptible(&adapter->reset_wait_queue);
+		}
+	}
+}
+
+/**
+ * ibmvmc_reset_task - Reset Task
+ *
+ * @data:	Data field
+ *
+ * Performs a CRQ reset of the VMC device in process context.
+ * NOTE: This function should not be called directly, use ibmvmc_reset.
+ */
+static int ibmvmc_reset_task(void *data)
+{
+	struct crq_server_adapter *adapter = data;
+	int rc;
+
+	set_user_nice(current, -20);
+
+	while (!kthread_should_stop()) {
+		wait_event_interruptible(adapter->reset_wait_queue,
+			(ibmvmc.state == ibmvmc_state_sched_reset) ||
+			kthread_should_stop());
+
+		if (kthread_should_stop())
+			break;
+
+		dev_dbg(adapter->dev, "CRQ resetting in process context");
+		tasklet_disable(&adapter->work_task);
+
+		rc = ibmvmc_reset_crq_queue(adapter);
+
+		if (rc != H_SUCCESS && rc != H_RESOURCE) {
+			dev_err(adapter->dev, "Error initializing CRQ.  rc = 0x%x\n",
+				rc);
+			ibmvmc.state = ibmvmc_state_failed;
+		} else {
+			ibmvmc.state = ibmvmc_state_crqinit;
+
+			if (ibmvmc_send_crq(adapter, 0xC001000000000000LL, 0)
+			    != 0 && rc != H_RESOURCE)
+				dev_warn(adapter->dev, "Failed to send initialize CRQ message\n");
+		}
+
+		vio_enable_interrupts(to_vio_dev(adapter->dev));
+		tasklet_enable(&adapter->work_task);
+	}
+
+	return 0;
+}
+
+/**
+ * ibmvmc_process_open_resp - Process Open Response
+ *
+ * @crq: ibmvmc_crq_msg struct
+ * @adapter:    crq_server_adapter struct
+ *
+ * This command is sent by the hypervisor in response to the Interface
+ * Open message. When this message is received, the indicated buffer is
+ * again available for management partition use.
+ */
+static void ibmvmc_process_open_resp(struct ibmvmc_crq_msg *crq,
+				     struct crq_server_adapter *adapter)
+{
+	unsigned char hmc_index;
+	unsigned short buffer_id;
+
+	hmc_index = crq->hmc_index;
+	if (hmc_index > ibmvmc.max_hmc_index) {
+		/* Why would PHYP give an index > max negotiated? */
+		ibmvmc_reset(adapter, false);
+		return;
+	}
+
+	if (crq->status) {
+		dev_warn(adapter->dev, "open_resp: failed - status 0x%x\n",
+			 crq->status);
+		ibmvmc_return_hmc(&hmcs[hmc_index], false);
+		return;
+	}
+
+	if (hmcs[hmc_index].state == ibmhmc_state_opening) {
+		buffer_id = be16_to_cpu(crq->var2.buffer_id);
+		if (buffer_id >= ibmvmc.max_buffer_pool_size) {
+			dev_err(adapter->dev, "open_resp: invalid buffer_id = 0x%x\n",
+				buffer_id);
+			hmcs[hmc_index].state = ibmhmc_state_failed;
+		} else {
+			ibmvmc_free_hmc_buffer(&hmcs[hmc_index],
+					       &hmcs[hmc_index].buffer[buffer_id]);
+			hmcs[hmc_index].state = ibmhmc_state_ready;
+			dev_dbg(adapter->dev, "open_resp: set hmc state = ready\n");
+		}
+	} else {
+		dev_warn(adapter->dev, "open_resp: invalid hmc state (0x%x)\n",
+			 hmcs[hmc_index].state);
+	}
+}
+
+/**
+ * ibmvmc_process_close_resp - Process Close Response
+ *
+ * @crq: ibmvmc_crq_msg struct
+ * @adapter:    crq_server_adapter struct
+ *
+ * This command is sent by the hypervisor in response to the managemant
+ * application Interface Close message.
+ *
+ * If the close fails, simply reset the entire driver as the state of the VMC
+ * must be in tough shape.
+ */
+static void ibmvmc_process_close_resp(struct ibmvmc_crq_msg *crq,
+				      struct crq_server_adapter *adapter)
+{
+	unsigned char hmc_index;
+
+	hmc_index = crq->hmc_index;
+	if (hmc_index > ibmvmc.max_hmc_index) {
+		ibmvmc_reset(adapter, false);
+		return;
+	}
+
+	if (crq->status) {
+		dev_warn(adapter->dev, "close_resp: failed - status 0x%x\n",
+			 crq->status);
+		ibmvmc_reset(adapter, false);
+		return;
+	}
+
+	ibmvmc_return_hmc(&hmcs[hmc_index], false);
+}
+
+/**
+ * ibmvmc_crq_process - Process CRQ
+ *
+ * @adapter:    crq_server_adapter struct
+ * @crq:	ibmvmc_crq_msg struct
+ *
+ * Process the CRQ message based upon the type of message received.
+ *
+ */
+static void ibmvmc_crq_process(struct crq_server_adapter *adapter,
+			       struct ibmvmc_crq_msg *crq)
+{
+	switch (crq->type) {
+	case VMC_MSG_CAP_RESP:
+		dev_dbg(adapter->dev, "CRQ recv: capabilities resp (0x%x)\n",
+			crq->type);
+		if (ibmvmc.state == ibmvmc_state_capabilities)
+			ibmvmc_process_capabilities(adapter, crq);
+		else
+			dev_warn(adapter->dev, "caps msg invalid in state 0x%x\n",
+				 ibmvmc.state);
+		break;
+	case VMC_MSG_OPEN_RESP:
+		dev_dbg(adapter->dev, "CRQ recv: open resp (0x%x)\n",
+			crq->type);
+		if (ibmvmc_validate_hmc_session(adapter, crq) == 0)
+			ibmvmc_process_open_resp(crq, adapter);
+		break;
+	case VMC_MSG_ADD_BUF:
+		dev_dbg(adapter->dev, "CRQ recv: add buf (0x%x)\n",
+			crq->type);
+		if (ibmvmc_validate_hmc_session(adapter, crq) == 0)
+			ibmvmc_add_buffer(adapter, crq);
+		break;
+	case VMC_MSG_REM_BUF:
+		dev_dbg(adapter->dev, "CRQ recv: rem buf (0x%x)\n",
+			crq->type);
+		if (ibmvmc_validate_hmc_session(adapter, crq) == 0)
+			ibmvmc_rem_buffer(adapter, crq);
+		break;
+	case VMC_MSG_SIGNAL:
+		dev_dbg(adapter->dev, "CRQ recv: signal msg (0x%x)\n",
+			crq->type);
+		if (ibmvmc_validate_hmc_session(adapter, crq) == 0)
+			ibmvmc_recv_msg(adapter, crq);
+		break;
+	case VMC_MSG_CLOSE_RESP:
+		dev_dbg(adapter->dev, "CRQ recv: close resp (0x%x)\n",
+			crq->type);
+		if (ibmvmc_validate_hmc_session(adapter, crq) == 0)
+			ibmvmc_process_close_resp(crq, adapter);
+		break;
+	case VMC_MSG_CAP:
+	case VMC_MSG_OPEN:
+	case VMC_MSG_CLOSE:
+	case VMC_MSG_ADD_BUF_RESP:
+	case VMC_MSG_REM_BUF_RESP:
+		dev_warn(adapter->dev, "CRQ recv: unexpected msg (0x%x)\n",
+			 crq->type);
+		break;
+	default:
+		dev_warn(adapter->dev, "CRQ recv: unknown msg (0x%x)\n",
+			 crq->type);
+		break;
+	}
+}
+
+/**
+ * ibmvmc_handle_crq_init - Handle CRQ Init
+ *
+ * @crq:	ibmvmc_crq_msg struct
+ * @adapter:	crq_server_adapter struct
+ *
+ * Handle the type of crq initialization based on whether
+ * it is a message or a response.
+ *
+ */
+static void ibmvmc_handle_crq_init(struct ibmvmc_crq_msg *crq,
+				   struct crq_server_adapter *adapter)
+{
+	switch (crq->type) {
+	case 0x01:	/* Initialization message */
+		dev_dbg(adapter->dev, "CRQ recv: CRQ init msg - state 0x%x\n",
+			ibmvmc.state);
+		if (ibmvmc.state == ibmvmc_state_crqinit) {
+			/* Send back a response */
+			if (ibmvmc_send_crq(adapter, 0xC002000000000000,
+					    0) == 0)
+				ibmvmc_send_capabilities(adapter);
+			else
+				dev_err(adapter->dev, " Unable to send init rsp\n");
+		} else {
+			dev_err(adapter->dev, "Invalid state 0x%x mtu = 0x%x\n",
+				ibmvmc.state, ibmvmc.max_mtu);
+		}
+
+		break;
+	case 0x02:	/* Initialization response */
+		dev_dbg(adapter->dev, "CRQ recv: initialization resp msg - state 0x%x\n",
+			ibmvmc.state);
+		if (ibmvmc.state == ibmvmc_state_crqinit)
+			ibmvmc_send_capabilities(adapter);
+		break;
+	default:
+		dev_warn(adapter->dev, "Unknown crq message type 0x%lx\n",
+			 (unsigned long)crq->type);
+	}
+}
+
+/**
+ * ibmvmc_handle_crq - Handle CRQ
+ *
+ * @crq:	ibmvmc_crq_msg struct
+ * @adapter:	crq_server_adapter struct
+ *
+ * Read the command elements from the command queue and execute the
+ * requests based upon the type of crq message.
+ *
+ */
+static void ibmvmc_handle_crq(struct ibmvmc_crq_msg *crq,
+			      struct crq_server_adapter *adapter)
+{
+	switch (crq->valid) {
+	case 0xC0:		/* initialization */
+		ibmvmc_handle_crq_init(crq, adapter);
+		break;
+	case 0xFF:	/* Hypervisor telling us the connection is closed */
+		dev_warn(adapter->dev, "CRQ recv: virtual adapter failed - resetting.\n");
+		ibmvmc_reset(adapter, true);
+		break;
+	case 0x80:	/* real payload */
+		ibmvmc_crq_process(adapter, crq);
+		break;
+	default:
+		dev_warn(adapter->dev, "CRQ recv: unknown msg 0x%02x.\n",
+			 crq->valid);
+		break;
+	}
+}
+
+static void ibmvmc_task(unsigned long data)
+{
+	struct crq_server_adapter *adapter =
+		(struct crq_server_adapter *)data;
+	struct vio_dev *vdev = to_vio_dev(adapter->dev);
+	struct ibmvmc_crq_msg *crq;
+	int done = 0;
+
+	while (!done) {
+		/* Pull all the valid messages off the CRQ */
+		while ((crq = crq_queue_next_crq(&adapter->queue)) != NULL) {
+			ibmvmc_handle_crq(crq, adapter);
+			crq->valid = 0x00;
+			/* CRQ reset was requested, stop processing CRQs.
+			 * Interrupts will be re-enabled by the reset task.
+			 */
+			if (ibmvmc.state == ibmvmc_state_sched_reset)
+				return;
+		}
+
+		vio_enable_interrupts(vdev);
+		crq = crq_queue_next_crq(&adapter->queue);
+		if (crq) {
+			vio_disable_interrupts(vdev);
+			ibmvmc_handle_crq(crq, adapter);
+			crq->valid = 0x00;
+			/* CRQ reset was requested, stop processing CRQs.
+			 * Interrupts will be re-enabled by the reset task.
+			 */
+			if (ibmvmc.state == ibmvmc_state_sched_reset)
+				return;
+		} else {
+			done = 1;
+		}
+	}
+}
+
+/**
+ * ibmvmc_init_crq_queue - Init CRQ Queue
+ *
+ * @adapter:	crq_server_adapter struct
+ *
+ * Return:
+ *	0 - Success
+ *	Non-zero - Failure
+ */
+static int ibmvmc_init_crq_queue(struct crq_server_adapter *adapter)
+{
+	struct vio_dev *vdev = to_vio_dev(adapter->dev);
+	struct crq_queue *queue = &adapter->queue;
+	int rc = 0;
+	int retrc = 0;
+
+	queue->msgs = (struct ibmvmc_crq_msg *)get_zeroed_page(GFP_KERNEL);
+
+	if (!queue->msgs)
+		goto malloc_failed;
+
+	queue->size = PAGE_SIZE / sizeof(*queue->msgs);
+
+	queue->msg_token = dma_map_single(adapter->dev, queue->msgs,
+					  queue->size * sizeof(*queue->msgs),
+					  DMA_BIDIRECTIONAL);
+
+	if (dma_mapping_error(adapter->dev, queue->msg_token))
+		goto map_failed;
+
+	retrc = plpar_hcall_norets(H_REG_CRQ,
+				   vdev->unit_address,
+				   queue->msg_token, PAGE_SIZE);
+	retrc = rc;
+
+	if (rc == H_RESOURCE)
+		rc = ibmvmc_reset_crq_queue(adapter);
+
+	if (rc == 2) {
+		dev_warn(adapter->dev, "Partner adapter not ready\n");
+		retrc = 0;
+	} else if (rc != 0) {
+		dev_err(adapter->dev, "Error %d opening adapter\n", rc);
+		goto reg_crq_failed;
+	}
+
+	queue->cur = 0;
+	spin_lock_init(&queue->lock);
+
+	tasklet_init(&adapter->work_task, ibmvmc_task, (unsigned long)adapter);
+
+	if (request_irq(vdev->irq,
+			ibmvmc_handle_event,
+			0, "ibmvmc", (void *)adapter) != 0) {
+		dev_err(adapter->dev, "couldn't register irq 0x%x\n",
+			vdev->irq);
+		goto req_irq_failed;
+	}
+
+	rc = vio_enable_interrupts(vdev);
+	if (rc != 0) {
+		dev_err(adapter->dev, "Error %d enabling interrupts!!!\n", rc);
+		goto req_irq_failed;
+	}
+
+	return retrc;
+
+req_irq_failed:
+	/* Cannot have any work since we either never got our IRQ registered,
+	 * or never got interrupts enabled
+	 */
+	tasklet_kill(&adapter->work_task);
+	h_free_crq(vdev->unit_address);
+reg_crq_failed:
+	dma_unmap_single(adapter->dev,
+			 queue->msg_token,
+			 queue->size * sizeof(*queue->msgs), DMA_BIDIRECTIONAL);
+map_failed:
+	free_page((unsigned long)queue->msgs);
+malloc_failed:
+	return -ENOMEM;
+}
+
+/* Fill in the liobn and riobn fields on the adapter */
+static int read_dma_window(struct vio_dev *vdev,
+			   struct crq_server_adapter *adapter)
+{
+	const __be32 *dma_window;
+	const __be32 *prop;
+
+	/* TODO Using of_parse_dma_window would be better, but it doesn't give
+	 * a way to read multiple windows without already knowing the size of
+	 * a window or the number of windows
+	 */
+	dma_window =
+		(const __be32 *)vio_get_attribute(vdev, "ibm,my-dma-window",
+						NULL);
+	if (!dma_window) {
+		dev_warn(adapter->dev, "Couldn't find ibm,my-dma-window property\n");
+		return -1;
+	}
+
+	adapter->liobn = be32_to_cpu(*dma_window);
+	dma_window++;
+
+	prop = (const __be32 *)vio_get_attribute(vdev, "ibm,#dma-address-cells",
+						NULL);
+	if (!prop) {
+		dev_warn(adapter->dev, "Couldn't find ibm,#dma-address-cells property\n");
+		dma_window++;
+	} else {
+		dma_window += be32_to_cpu(*prop);
+	}
+
+	prop = (const __be32 *)vio_get_attribute(vdev, "ibm,#dma-size-cells",
+						NULL);
+	if (!prop) {
+		dev_warn(adapter->dev, "Couldn't find ibm,#dma-size-cells property\n");
+		dma_window++;
+	} else {
+		dma_window += be32_to_cpu(*prop);
+	}
+
+	/* dma_window should point to the second window now */
+	adapter->riobn = be32_to_cpu(*dma_window);
+
+	return 0;
+}
+
+static int ibmvmc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
+{
+	struct crq_server_adapter *adapter = &ibmvmc_adapter;
+	int rc;
+
+	dev_set_drvdata(&vdev->dev, NULL);
+	memset(adapter, 0, sizeof(*adapter));
+	adapter->dev = &vdev->dev;
+
+	dev_info(adapter->dev, "Probe for UA 0x%x\n", vdev->unit_address);
+
+	rc = read_dma_window(vdev, adapter);
+	if (rc != 0) {
+		ibmvmc.state = ibmvmc_state_failed;
+		return -1;
+	}
+
+	dev_dbg(adapter->dev, "Probe: liobn 0x%x, riobn 0x%x\n",
+		adapter->liobn, adapter->riobn);
+
+	init_waitqueue_head(&adapter->reset_wait_queue);
+	adapter->reset_task = kthread_run(ibmvmc_reset_task, adapter, "ibmvmc");
+	if (IS_ERR(adapter->reset_task)) {
+		dev_err(adapter->dev, "Failed to start reset thread\n");
+		ibmvmc.state = ibmvmc_state_failed;
+		rc = PTR_ERR(adapter->reset_task);
+		adapter->reset_task = NULL;
+		return rc;
+	}
+
+	rc = ibmvmc_init_crq_queue(adapter);
+	if (rc != 0 && rc != H_RESOURCE) {
+		dev_err(adapter->dev, "Error initializing CRQ.  rc = 0x%x\n",
+			rc);
+		ibmvmc.state = ibmvmc_state_failed;
+		goto crq_failed;
+	}
+
+	ibmvmc.state = ibmvmc_state_crqinit;
+
+	/* Try to send an initialization message.  Note that this is allowed
+	 * to fail if the other end is not acive.  In that case we just wait
+	 * for the other side to initialize.
+	 */
+	if (ibmvmc_send_crq(adapter, 0xC001000000000000LL, 0) != 0 &&
+	    rc != H_RESOURCE)
+		dev_warn(adapter->dev, "Failed to send initialize CRQ message\n");
+
+	dev_set_drvdata(&vdev->dev, adapter);
+
+	return 0;
+
+crq_failed:
+	kthread_stop(adapter->reset_task);
+	adapter->reset_task = NULL;
+	return -EPERM;
+}
+
+static int ibmvmc_remove(struct vio_dev *vdev)
+{
+	struct crq_server_adapter *adapter = dev_get_drvdata(&vdev->dev);
+
+	dev_info(adapter->dev, "Entering remove for UA 0x%x\n",
+		 vdev->unit_address);
+	ibmvmc_release_crq_queue(adapter);
+
+	return 0;
+}
+
+static struct vio_device_id ibmvmc_device_table[] = {
+	{ "ibm,vmc", "IBM,vmc" },
+	{ "", "" }
+};
+MODULE_DEVICE_TABLE(vio, ibmvmc_device_table);
+
+static struct vio_driver ibmvmc_driver = {
+	.name        = ibmvmc_driver_name,
+	.id_table    = ibmvmc_device_table,
+	.probe       = ibmvmc_probe,
+	.remove      = ibmvmc_remove,
+};
+
+static void __init ibmvmc_scrub_module_parms(void)
+{
+	if (ibmvmc_max_mtu > MAX_MTU) {
+		pr_warn("ibmvmc: Max MTU reduced to %d\n", MAX_MTU);
+		ibmvmc_max_mtu = MAX_MTU;
+	} else if (ibmvmc_max_mtu < MIN_MTU) {
+		pr_warn("ibmvmc: Max MTU increased to %d\n", MIN_MTU);
+		ibmvmc_max_mtu = MIN_MTU;
+	}
+
+	if (ibmvmc_max_buf_pool_size > MAX_BUF_POOL_SIZE) {
+		pr_warn("ibmvmc: Max buffer pool size reduced to %d\n",
+			MAX_BUF_POOL_SIZE);
+		ibmvmc_max_buf_pool_size = MAX_BUF_POOL_SIZE;
+	} else if (ibmvmc_max_buf_pool_size < MIN_BUF_POOL_SIZE) {
+		pr_warn("ibmvmc: Max buffer pool size increased to %d\n",
+			MIN_BUF_POOL_SIZE);
+		ibmvmc_max_buf_pool_size = MIN_BUF_POOL_SIZE;
+	}
+
+	if (ibmvmc_max_hmcs > MAX_HMCS) {
+		pr_warn("ibmvmc: Max HMCs reduced to %d\n", MAX_HMCS);
+		ibmvmc_max_hmcs = MAX_HMCS;
+	} else if (ibmvmc_max_hmcs < MIN_HMCS) {
+		pr_warn("ibmvmc: Max HMCs increased to %d\n", MIN_HMCS);
+		ibmvmc_max_hmcs = MIN_HMCS;
+	}
+}
+
+static struct miscdevice ibmvmc_miscdev = {
+	.name = ibmvmc_driver_name,
+	.minor = MISC_DYNAMIC_MINOR,
+	.fops = &ibmvmc_fops,
+};
+
+static int __init ibmvmc_module_init(void)
+{
+	int rc, i, j;
+
+	ibmvmc.state = ibmvmc_state_initial;
+	pr_info("ibmvmc: version %s\n", IBMVMC_DRIVER_VERSION);
+
+	rc = misc_register(&ibmvmc_miscdev);
+	if (rc) {
+		pr_err("ibmvmc: misc registration failed\n");
+		goto misc_register_failed;
+	}
+	pr_info("ibmvmc: node %d:%d\n", MISC_MAJOR,
+		ibmvmc_miscdev.minor);
+
+	/* Initialize data structures */
+	memset(hmcs, 0, sizeof(struct ibmvmc_hmc) * MAX_HMCS);
+	for (i = 0; i < MAX_HMCS; i++) {
+		spin_lock_init(&hmcs[i].lock);
+		hmcs[i].state = ibmhmc_state_free;
+		for (j = 0; j < MAX_BUF_POOL_SIZE; j++)
+			hmcs[i].queue_outbound_msgs[j] = VMC_INVALID_BUFFER_ID;
+	}
+
+	/* Sanity check module parms */
+	ibmvmc_scrub_module_parms();
+
+	/*
+	 * Initialize some reasonable values.  Might be negotiated smaller
+	 * values during the capabilities exchange.
+	 */
+	ibmvmc.max_mtu = ibmvmc_max_mtu;
+	ibmvmc.max_buffer_pool_size = ibmvmc_max_buf_pool_size;
+	ibmvmc.max_hmc_index = ibmvmc_max_hmcs - 1;
+
+	rc = vio_register_driver(&ibmvmc_driver);
+
+	if (rc) {
+		pr_err("ibmvmc: rc %d from vio_register_driver\n", rc);
+		goto vio_reg_failed;
+	}
+
+	return 0;
+
+vio_reg_failed:
+	misc_deregister(&ibmvmc_miscdev);
+misc_register_failed:
+	return rc;
+}
+
+static void __exit ibmvmc_module_exit(void)
+{
+	pr_info("ibmvmc: module exit\n");
+	vio_unregister_driver(&ibmvmc_driver);
+	misc_deregister(&ibmvmc_miscdev);
+}
+
+module_init(ibmvmc_module_init);
+module_exit(ibmvmc_module_exit);
+
+module_param_named(buf_pool_size, ibmvmc_max_buf_pool_size,
+		   int, 0644);
+MODULE_PARM_DESC(buf_pool_size, "Buffer pool size");
+module_param_named(max_hmcs, ibmvmc_max_hmcs, int, 0644);
+MODULE_PARM_DESC(max_hmcs, "Max HMCs");
+module_param_named(max_mtu, ibmvmc_max_mtu, int, 0644);
+MODULE_PARM_DESC(max_mtu, "Max MTU");
+
+MODULE_AUTHOR("Steven Royer <[e-mail]>");
+MODULE_DESCRIPTION("IBM VMC");
+MODULE_VERSION(IBMVMC_DRIVER_VERSION);
+MODULE_LICENSE("GPL v2");

drivers/misc/ibmvmc.h

···
+/* SPDX-License-Identifier: GPL-2.0+
+ *
+ * linux/drivers/misc/ibmvmc.h
+ *
+ * IBM Power Systems Virtual Management Channel Support.
+ *
+ * Copyright (c) 2004, 2018 IBM Corp.
+ *   Dave Engebretsen [e-mail]
+ *   Steven Royer [e-mail]
+ *   Adam Reznechek [e-mail]
+ *   Bryant G. Ly <[e-mail]>
+ */
+#ifndef IBMVMC_H
+#define IBMVMC_H
+
+#include <linux/types.h>
+#include <linux/cdev.h>
+
+#include <asm/vio.h>
+
+#define IBMVMC_PROTOCOL_VERSION    0x0101
+
+#define MIN_BUF_POOL_SIZE 16
+#define MIN_HMCS          1
+#define MIN_MTU           4096
+#define MAX_BUF_POOL_SIZE 64
+#define MAX_HMCS          2
+#define MAX_MTU           (4 * 4096)
+#define DEFAULT_BUF_POOL_SIZE 32
+#define DEFAULT_HMCS          1
+#define DEFAULT_MTU           4096
+#define HMC_ID_LEN        32
+
+#define VMC_INVALID_BUFFER_ID 0xFFFF
+
+/* ioctl numbers */
+#define VMC_BASE	     0xCC
+#define VMC_IOCTL_SETHMCID   _IOW(VMC_BASE, 0x00, unsigned char *)
+#define VMC_IOCTL_QUERY      _IOR(VMC_BASE, 0x01, struct ibmvmc_query_struct)
+#define VMC_IOCTL_REQUESTVMC _IOR(VMC_BASE, 0x02, u32)
+
+#define VMC_MSG_CAP          0x01
+#define VMC_MSG_CAP_RESP     0x81
+#define VMC_MSG_OPEN         0x02
+#define VMC_MSG_OPEN_RESP    0x82
+#define VMC_MSG_CLOSE        0x03
+#define VMC_MSG_CLOSE_RESP   0x83
+#define VMC_MSG_ADD_BUF      0x04
+#define VMC_MSG_ADD_BUF_RESP 0x84
+#define VMC_MSG_REM_BUF      0x05
+#define VMC_MSG_REM_BUF_RESP 0x85
+#define VMC_MSG_SIGNAL       0x06
+
+#define VMC_MSG_SUCCESS 0
+#define VMC_MSG_INVALID_HMC_INDEX 1
+#define VMC_MSG_INVALID_BUFFER_ID 2
+#define VMC_MSG_CLOSED_HMC        3
+#define VMC_MSG_INTERFACE_FAILURE 4
+#define VMC_MSG_NO_BUFFER         5
+
+#define VMC_BUF_OWNER_ALPHA 0
+#define VMC_BUF_OWNER_HV    1
+
+enum ibmvmc_states {
+	ibmvmc_state_sched_reset  = -1,
+	ibmvmc_state_initial      = 0,
+	ibmvmc_state_crqinit      = 1,
+	ibmvmc_state_capabilities = 2,
+	ibmvmc_state_ready        = 3,
+	ibmvmc_state_failed       = 4,
+};
+
+enum ibmhmc_states {
+	/* HMC connection not established */
+	ibmhmc_state_free    = 0,
+
+	/* HMC connection established (open called) */
+	ibmhmc_state_initial = 1,
+
+	/* open msg sent to HV, due to ioctl(1) call */
+	ibmhmc_state_opening = 2,
+
+	/* HMC connection ready, open resp msg from HV */
+	ibmhmc_state_ready   = 3,
+
+	/* HMC connection failure */
+	ibmhmc_state_failed  = 4,
+};
+
+struct ibmvmc_buffer {
+	u8 valid;	/* 1 when DMA storage allocated to buffer          */
+	u8 free;	/* 1 when buffer available for the Alpha Partition */
+	u8 owner;
+	u16 id;
+	u32 size;
+	u32 msg_len;
+	dma_addr_t dma_addr_local;
+	dma_addr_t dma_addr_remote;
+	void *real_addr_local;
+};
+
+struct ibmvmc_admin_crq_msg {
+	u8 valid;	/* RPA Defined           */
+	u8 type;	/* ibmvmc msg type       */
+	u8 status;	/* Response msg status. Zero is success and on failure,
+			 * either 1 - General Failure, or 2 - Invalid Version is
+			 * returned.
+			 */
+	u8 rsvd[2];
+	u8 max_hmc;	/* Max # of independent HMC connections supported */
+	__be16 pool_size;	/* Maximum number of buffers supported per HMC
+				 * connection
+				 */
+	__be32 max_mtu;		/* Maximum message size supported (bytes) */
+	__be16 crq_size;	/* # of entries available in the CRQ for the
+				 * source partition. The target partition must
+				 * limit the number of outstanding messages to
+				 * one half or less.
+				 */
+	__be16 version;	/* Indicates the code level of the management partition
+			 * or the hypervisor with the high-order byte
+			 * indicating a major version and the low-order byte
+			 * indicating a minor version.
+			 */
+};
+
+struct ibmvmc_crq_msg {
+	u8 valid;     /* RPA Defined           */
+	u8 type;      /* ibmvmc msg type       */
+	u8 status;    /* Response msg status   */
+	union {
+		u8 rsvd;  /* Reserved              */
+		u8 owner;
+	} var1;
+	u8 hmc_session;	/* Session Identifier for the current VMC connection */
+	u8 hmc_index;	/* A unique HMC Idx would be used if multiple management
+			 * applications running concurrently were desired
+			 */
+	union {
+		__be16 rsvd;
+		__be16 buffer_id;
+	} var2;
+	__be32 rsvd;
+	union {
+		__be32 rsvd;
+		__be32 lioba;
+		__be32 msg_len;
+	} var3;
+};
+
+/* an RPA command/response transport queue */
+struct crq_queue {
+	struct ibmvmc_crq_msg *msgs;
+	int size, cur;
+	dma_addr_t msg_token;
+	spinlock_t lock;
+};
+
+/* VMC server adapter settings */
+struct crq_server_adapter {
+	struct device *dev;
+	struct crq_queue queue;
+	u32 liobn;
+	u32 riobn;
+	struct tasklet_struct work_task;
+	wait_queue_head_t reset_wait_queue;
+	struct task_struct *reset_task;
+};
+
+/* Driver wide settings */
+struct ibmvmc_struct {
+	u32 state;
+	u32 max_mtu;
+	u32 max_buffer_pool_size;
+	u32 max_hmc_index;
+	struct crq_server_adapter *adapter;
+	struct cdev cdev;
+	u32 vmc_drc_index;
+};
+
+struct ibmvmc_file_session;
+
+/* Connection specific settings */
+struct ibmvmc_hmc {
+	u8 session;
+	u8 index;
+	u32 state;
+	struct crq_server_adapter *adapter;
+	spinlock_t lock;
+	unsigned char hmc_id[HMC_ID_LEN];
+	struct ibmvmc_buffer buffer[MAX_BUF_POOL_SIZE];
+	unsigned short queue_outbound_msgs[MAX_BUF_POOL_SIZE];
+	int queue_head, queue_tail;
+	struct ibmvmc_file_session *file_session;
+};
+
+struct ibmvmc_file_session {
+	struct file *file;
+	struct ibmvmc_hmc *hmc;
+	bool valid;
+};
+
+struct ibmvmc_query_struct {
+	int have_vmc;
+	int state;
+	int vmc_drc_index;
+};
+
+#endif /* __IBMVMC_H */