drivers: visorbus: move driver out of staging

Move the visorbus driver out of staging (drivers/staging/unisys/visorbus)
and to drivers/visorbus. Modify the configuration and makefiles so they
now reference the new location. The s-Par header file visorbus.h that is
referenced by all s-Par drivers, is being moved into include/linux.

Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <timothy.sell@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1686 insertions, 0 deletions

diff --git a/drivers/visorbus/visorchipset.c b/drivers/visorbus/visorchipset.c
new file mode 100644
index 000000000000..ca752b8f495f
--- /dev/null
+++ b/drivers/visorbus/visorchipset.c
@@ -0,0 +1,1686 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2010 - 2015 UNISYS CORPORATION
+ * All rights reserved.
+ */
+
+#include <linux/acpi.h>
+#include <linux/crash_dump.h>
+#include <linux/visorbus.h>
+
+#include "visorbus_private.h"
+
+/* {72120008-4AAB-11DC-8530-444553544200} */
+#define VISOR_SIOVM_GUID GUID_INIT(0x72120008, 0x4AAB, 0x11DC, 0x85, 0x30, \
+				   0x44, 0x45, 0x53, 0x54, 0x42, 0x00)
+
+static const guid_t visor_vhba_channel_guid = VISOR_VHBA_CHANNEL_GUID;
+static const guid_t visor_siovm_guid = VISOR_SIOVM_GUID;
+static const guid_t visor_controlvm_channel_guid = VISOR_CONTROLVM_CHANNEL_GUID;
+
+#define POLLJIFFIES_CONTROLVM_FAST 1
+#define POLLJIFFIES_CONTROLVM_SLOW 100
+
+#define MAX_CONTROLVM_PAYLOAD_BYTES (1024 * 128)
+
+#define UNISYS_VISOR_LEAF_ID 0x40000000
+
+/* The s-Par leaf ID returns "UnisysSpar64" encoded across ebx, ecx, edx */
+#define UNISYS_VISOR_ID_EBX 0x73696e55
+#define UNISYS_VISOR_ID_ECX 0x70537379
+#define UNISYS_VISOR_ID_EDX 0x34367261
+
+/*
+ * When the controlvm channel is idle for at least MIN_IDLE_SECONDS, we switch
+ * to slow polling mode. As soon as we get a controlvm message, we switch back
+ * to fast polling mode.
+ */
+#define MIN_IDLE_SECONDS 10
+
+struct parser_context {
+	unsigned long allocbytes;
+	unsigned long param_bytes;
+	u8 *curr;
+	unsigned long bytes_remaining;
+	bool byte_stream;
+	struct visor_controlvm_parameters_header data;
+};
+
+/* VMCALL_CONTROLVM_ADDR: Used by all guests, not just IO. */
+#define VMCALL_CONTROLVM_ADDR 0x0501
+
+enum vmcall_result {
+	VMCALL_RESULT_SUCCESS = 0,
+	VMCALL_RESULT_INVALID_PARAM = 1,
+	VMCALL_RESULT_DATA_UNAVAILABLE = 2,
+	VMCALL_RESULT_FAILURE_UNAVAILABLE = 3,
+	VMCALL_RESULT_DEVICE_ERROR = 4,
+	VMCALL_RESULT_DEVICE_NOT_READY = 5
+};
+
+/*
+ * struct vmcall_io_controlvm_addr_params - Structure for IO VMCALLS. Has
+ *					    parameters to VMCALL_CONTROLVM_ADDR
+ *					    interface.
+ * @address:	   The Guest-relative physical address of the ControlVm channel.
+ *		   This VMCall fills this in with the appropriate address.
+ *		   Contents provided by this VMCALL (OUT).
+ * @channel_bytes: The size of the ControlVm channel in bytes This VMCall fills
+ *		   this in with the appropriate address. Contents provided by
+ *		   this VMCALL (OUT).
+ * @unused:	   Unused Bytes in the 64-Bit Aligned Struct.
+ */
+struct vmcall_io_controlvm_addr_params {
+	u64 address;
+	u32 channel_bytes;
+	u8 unused[4];
+} __packed;
+
+struct visorchipset_device {
+	struct acpi_device *acpi_device;
+	unsigned long poll_jiffies;
+	/* when we got our last controlvm message */
+	unsigned long most_recent_message_jiffies;
+	struct delayed_work periodic_controlvm_work;
+	struct visorchannel *controlvm_channel;
+	unsigned long controlvm_payload_bytes_buffered;
+	/*
+	 * The following variables are used to handle the scenario where we are
+	 * unable to offload the payload from a controlvm message due to memory
+	 * requirements. In this scenario, we simply stash the controlvm
+	 * message, then attempt to process it again the next time
+	 * controlvm_periodic_work() runs.
+	 */
+	struct controlvm_message controlvm_pending_msg;
+	bool controlvm_pending_msg_valid;
+	struct vmcall_io_controlvm_addr_params controlvm_params;
+};
+
+static struct visorchipset_device *chipset_dev;
+
+struct parahotplug_request {
+	struct list_head list;
+	int id;
+	unsigned long expiration;
+	struct controlvm_message msg;
+};
+
+/* prototypes for attributes */
+static ssize_t toolaction_show(struct device *dev,
+			       struct device_attribute *attr,
+			       char *buf)
+{
+	u8 tool_action = 0;
+	int err;
+
+	err = visorchannel_read(chipset_dev->controlvm_channel,
+				offsetof(struct visor_controlvm_channel,
+					 tool_action),
+				&tool_action, sizeof(u8));
+	if (err)
+		return err;
+	return sprintf(buf, "%u\n", tool_action);
+}
+
+static ssize_t toolaction_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	u8 tool_action;
+	int err;
+
+	if (kstrtou8(buf, 10, &tool_action))
+		return -EINVAL;
+	err = visorchannel_write(chipset_dev->controlvm_channel,
+				 offsetof(struct visor_controlvm_channel,
+					  tool_action),
+				 &tool_action, sizeof(u8));
+	if (err)
+		return err;
+	return count;
+}
+static DEVICE_ATTR_RW(toolaction);
+
+static ssize_t boottotool_show(struct device *dev,
+			       struct device_attribute *attr,
+			       char *buf)
+{
+	struct efi_visor_indication efi_visor_indication;
+	int err;
+
+	err = visorchannel_read(chipset_dev->controlvm_channel,
+				offsetof(struct visor_controlvm_channel,
+					 efi_visor_ind),
+				&efi_visor_indication,
+				sizeof(struct efi_visor_indication));
+	if (err)
+		return err;
+	return sprintf(buf, "%u\n", efi_visor_indication.boot_to_tool);
+}
+
+static ssize_t boottotool_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	int val, err;
+	struct efi_visor_indication efi_visor_indication;
+
+	if (kstrtoint(buf, 10, &val))
+		return -EINVAL;
+	efi_visor_indication.boot_to_tool = val;
+	err = visorchannel_write(chipset_dev->controlvm_channel,
+				 offsetof(struct visor_controlvm_channel,
+					  efi_visor_ind),
+				 &(efi_visor_indication),
+				 sizeof(struct efi_visor_indication));
+	if (err)
+		return err;
+	return count;
+}
+static DEVICE_ATTR_RW(boottotool);
+
+static ssize_t error_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	u32 error = 0;
+	int err;
+
+	err = visorchannel_read(chipset_dev->controlvm_channel,
+				offsetof(struct visor_controlvm_channel,
+					 installation_error),
+				&error, sizeof(u32));
+	if (err)
+		return err;
+	return sprintf(buf, "%u\n", error);
+}
+
+static ssize_t error_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	u32 error;
+	int err;
+
+	if (kstrtou32(buf, 10, &error))
+		return -EINVAL;
+	err = visorchannel_write(chipset_dev->controlvm_channel,
+				 offsetof(struct visor_controlvm_channel,
+					  installation_error),
+				 &error, sizeof(u32));
+	if (err)
+		return err;
+	return count;
+}
+static DEVICE_ATTR_RW(error);
+
+static ssize_t textid_show(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	u32 text_id = 0;
+	int err;
+
+	err = visorchannel_read(chipset_dev->controlvm_channel,
+				offsetof(struct visor_controlvm_channel,
+					 installation_text_id),
+				&text_id, sizeof(u32));
+	if (err)
+		return err;
+	return sprintf(buf, "%u\n", text_id);
+}
+
+static ssize_t textid_store(struct device *dev, struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	u32 text_id;
+	int err;
+
+	if (kstrtou32(buf, 10, &text_id))
+		return -EINVAL;
+	err = visorchannel_write(chipset_dev->controlvm_channel,
+				 offsetof(struct visor_controlvm_channel,
+					  installation_text_id),
+				 &text_id, sizeof(u32));
+	if (err)
+		return err;
+	return count;
+}
+static DEVICE_ATTR_RW(textid);
+
+static ssize_t remaining_steps_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	u16 remaining_steps = 0;
+	int err;
+
+	err = visorchannel_read(chipset_dev->controlvm_channel,
+				offsetof(struct visor_controlvm_channel,
+					 installation_remaining_steps),
+				&remaining_steps, sizeof(u16));
+	if (err)
+		return err;
+	return sprintf(buf, "%hu\n", remaining_steps);
+}
+
+static ssize_t remaining_steps_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	u16 remaining_steps;
+	int err;
+
+	if (kstrtou16(buf, 10, &remaining_steps))
+		return -EINVAL;
+	err = visorchannel_write(chipset_dev->controlvm_channel,
+				 offsetof(struct visor_controlvm_channel,
+					  installation_remaining_steps),
+				 &remaining_steps, sizeof(u16));
+	if (err)
+		return err;
+	return count;
+}
+static DEVICE_ATTR_RW(remaining_steps);
+
+static void controlvm_init_response(struct controlvm_message *msg,
+				    struct controlvm_message_header *msg_hdr,
+				    int response)
+{
+	memset(msg, 0, sizeof(struct controlvm_message));
+	memcpy(&msg->hdr, msg_hdr, sizeof(struct controlvm_message_header));
+	msg->hdr.payload_bytes = 0;
+	msg->hdr.payload_vm_offset = 0;
+	msg->hdr.payload_max_bytes = 0;
+	if (response < 0) {
+		msg->hdr.flags.failed = 1;
+		msg->hdr.completion_status = (u32)(-response);
+	}
+}
+
+static int controlvm_respond_chipset_init(
+				struct controlvm_message_header *msg_hdr,
+				int response,
+				enum visor_chipset_feature features)
+{
+	struct controlvm_message outmsg;
+
+	controlvm_init_response(&outmsg, msg_hdr, response);
+	outmsg.cmd.init_chipset.features = features;
+	return visorchannel_signalinsert(chipset_dev->controlvm_channel,
+					 CONTROLVM_QUEUE_REQUEST, &outmsg);
+}
+
+static int chipset_init(struct controlvm_message *inmsg)
+{
+	static int chipset_inited;
+	enum visor_chipset_feature features = 0;
+	int rc = CONTROLVM_RESP_SUCCESS;
+	int res = 0;
+
+	if (chipset_inited) {
+		rc = -CONTROLVM_RESP_ALREADY_DONE;
+		res = -EIO;
+		goto out_respond;
+	}
+	chipset_inited = 1;
+	/*
+	 * Set features to indicate we support parahotplug (if Command also
+	 * supports it). Set the "reply" bit so Command knows this is a
+	 * features-aware driver.
+	 */
+	features = inmsg->cmd.init_chipset.features &
+		   VISOR_CHIPSET_FEATURE_PARA_HOTPLUG;
+	features |= VISOR_CHIPSET_FEATURE_REPLY;
+
+out_respond:
+	if (inmsg->hdr.flags.response_expected)
+		res = controlvm_respond_chipset_init(&inmsg->hdr, rc, features);
+
+	return res;
+}
+
+static int controlvm_respond(struct controlvm_message_header *msg_hdr,
+			     int response, struct visor_segment_state *state)
+{
+	struct controlvm_message outmsg;
+
+	controlvm_init_response(&outmsg, msg_hdr, response);
+	if (outmsg.hdr.flags.test_message == 1)
+		return -EINVAL;
+	if (state) {
+		outmsg.cmd.device_change_state.state = *state;
+		outmsg.cmd.device_change_state.flags.phys_device = 1;
+	}
+	return visorchannel_signalinsert(chipset_dev->controlvm_channel,
+					 CONTROLVM_QUEUE_REQUEST, &outmsg);
+}
+
+enum crash_obj_type {
+	CRASH_DEV,
+	CRASH_BUS,
+};
+
+static int save_crash_message(struct controlvm_message *msg,
+			      enum crash_obj_type cr_type)
+{
+	u32 local_crash_msg_offset;
+	u16 local_crash_msg_count;
+	int err;
+
+	err = visorchannel_read(chipset_dev->controlvm_channel,
+				offsetof(struct visor_controlvm_channel,
+					 saved_crash_message_count),
+				&local_crash_msg_count, sizeof(u16));
+	if (err) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"failed to read message count\n");
+		return err;
+	}
+	if (local_crash_msg_count != CONTROLVM_CRASHMSG_MAX) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"invalid number of messages\n");
+		return -EIO;
+	}
+	err = visorchannel_read(chipset_dev->controlvm_channel,
+				offsetof(struct visor_controlvm_channel,
+					 saved_crash_message_offset),
+				&local_crash_msg_offset, sizeof(u32));
+	if (err) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"failed to read offset\n");
+		return err;
+	}
+	switch (cr_type) {
+	case CRASH_DEV:
+		local_crash_msg_offset += sizeof(struct controlvm_message);
+		err = visorchannel_write(chipset_dev->controlvm_channel,
+					 local_crash_msg_offset, msg,
+					 sizeof(struct controlvm_message));
+		if (err) {
+			dev_err(&chipset_dev->acpi_device->dev,
+				"failed to write dev msg\n");
+			return err;
+		}
+		break;
+	case CRASH_BUS:
+		err = visorchannel_write(chipset_dev->controlvm_channel,
+					 local_crash_msg_offset, msg,
+					 sizeof(struct controlvm_message));
+		if (err) {
+			dev_err(&chipset_dev->acpi_device->dev,
+				"failed to write bus msg\n");
+			return err;
+		}
+		break;
+	default:
+		dev_err(&chipset_dev->acpi_device->dev,
+			"Invalid crash_obj_type\n");
+		break;
+	}
+	return 0;
+}
+
+static int controlvm_responder(enum controlvm_id cmd_id,
+			       struct controlvm_message_header *pending_msg_hdr,
+			       int response)
+{
+	if (pending_msg_hdr->id != (u32)cmd_id)
+		return -EINVAL;
+
+	return controlvm_respond(pending_msg_hdr, response, NULL);
+}
+
+static int device_changestate_responder(enum controlvm_id cmd_id,
+					struct visor_device *p, int response,
+					struct visor_segment_state state)
+{
+	struct controlvm_message outmsg;
+
+	if (p->pending_msg_hdr->id != cmd_id)
+		return -EINVAL;
+
+	controlvm_init_response(&outmsg, p->pending_msg_hdr, response);
+	outmsg.cmd.device_change_state.bus_no = p->chipset_bus_no;
+	outmsg.cmd.device_change_state.dev_no = p->chipset_dev_no;
+	outmsg.cmd.device_change_state.state = state;
+	return visorchannel_signalinsert(chipset_dev->controlvm_channel,
+					 CONTROLVM_QUEUE_REQUEST, &outmsg);
+}
+
+static int visorbus_create(struct controlvm_message *inmsg)
+{
+	struct controlvm_message_packet *cmd = &inmsg->cmd;
+	struct controlvm_message_header *pmsg_hdr;
+	u32 bus_no = cmd->create_bus.bus_no;
+	struct visor_device *bus_info;
+	struct visorchannel *visorchannel;
+	int err;
+
+	bus_info = visorbus_get_device_by_id(bus_no, BUS_ROOT_DEVICE, NULL);
+	if (bus_info && bus_info->state.created == 1) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"failed %s: already exists\n", __func__);
+		err = -EEXIST;
+		goto err_respond;
+	}
+	bus_info = kzalloc(sizeof(*bus_info), GFP_KERNEL);
+	if (!bus_info) {
+		err = -ENOMEM;
+		goto err_respond;
+	}
+	INIT_LIST_HEAD(&bus_info->list_all);
+	bus_info->chipset_bus_no = bus_no;
+	bus_info->chipset_dev_no = BUS_ROOT_DEVICE;
+	if (guid_equal(&cmd->create_bus.bus_inst_guid, &visor_siovm_guid)) {
+		err = save_crash_message(inmsg, CRASH_BUS);
+		if (err)
+			goto err_free_bus_info;
+	}
+	if (inmsg->hdr.flags.response_expected == 1) {
+		pmsg_hdr = kzalloc(sizeof(*pmsg_hdr), GFP_KERNEL);
+		if (!pmsg_hdr) {
+			err = -ENOMEM;
+			goto err_free_bus_info;
+		}
+		memcpy(pmsg_hdr, &inmsg->hdr,
+		       sizeof(struct controlvm_message_header));
+		bus_info->pending_msg_hdr = pmsg_hdr;
+	}
+	visorchannel = visorchannel_create(cmd->create_bus.channel_addr,
+					   GFP_KERNEL,
+					   &cmd->create_bus.bus_data_type_guid,
+					   false);
+	if (!visorchannel) {
+		err = -ENOMEM;
+		goto err_free_pending_msg;
+	}
+	bus_info->visorchannel = visorchannel;
+	/* Response will be handled by visorbus_create_instance on success */
+	err = visorbus_create_instance(bus_info);
+	if (err)
+		goto err_destroy_channel;
+	return 0;
+
+err_destroy_channel:
+	visorchannel_destroy(visorchannel);
+
+err_free_pending_msg:
+	kfree(bus_info->pending_msg_hdr);
+
+err_free_bus_info:
+	kfree(bus_info);
+
+err_respond:
+	if (inmsg->hdr.flags.response_expected == 1)
+		controlvm_responder(inmsg->hdr.id, &inmsg->hdr, err);
+	return err;
+}
+
+static int visorbus_destroy(struct controlvm_message *inmsg)
+{
+	struct controlvm_message_header *pmsg_hdr;
+	u32 bus_no = inmsg->cmd.destroy_bus.bus_no;
+	struct visor_device *bus_info;
+	int err;
+
+	bus_info = visorbus_get_device_by_id(bus_no, BUS_ROOT_DEVICE, NULL);
+	if (!bus_info) {
+		err = -ENODEV;
+		goto err_respond;
+	}
+	if (bus_info->state.created == 0) {
+		err = -ENOENT;
+		goto err_respond;
+	}
+	if (bus_info->pending_msg_hdr) {
+		/* only non-NULL if dev is still waiting on a response */
+		err = -EEXIST;
+		goto err_respond;
+	}
+	if (inmsg->hdr.flags.response_expected == 1) {
+		pmsg_hdr = kzalloc(sizeof(*pmsg_hdr), GFP_KERNEL);
+		if (!pmsg_hdr) {
+			err = -ENOMEM;
+			goto err_respond;
+		}
+		memcpy(pmsg_hdr, &inmsg->hdr,
+		       sizeof(struct controlvm_message_header));
+		bus_info->pending_msg_hdr = pmsg_hdr;
+	}
+	/* Response will be handled by visorbus_remove_instance */
+	visorbus_remove_instance(bus_info);
+	return 0;
+
+err_respond:
+	if (inmsg->hdr.flags.response_expected == 1)
+		controlvm_responder(inmsg->hdr.id, &inmsg->hdr, err);
+	return err;
+}
+
+static const guid_t *parser_id_get(struct parser_context *ctx)
+{
+	return &ctx->data.id;
+}
+
+static void *parser_string_get(u8 *pscan, int nscan)
+{
+	int value_length;
+	void *value;
+
+	if (nscan == 0)
+		return NULL;
+
+	value_length = strnlen(pscan, nscan);
+	value = kzalloc(value_length + 1, GFP_KERNEL);
+	if (!value)
+		return NULL;
+	if (value_length > 0)
+		memcpy(value, pscan, value_length);
+	return value;
+}
+
+static void *parser_name_get(struct parser_context *ctx)
+{
+	struct visor_controlvm_parameters_header *phdr;
+
+	phdr = &ctx->data;
+	if ((unsigned long)phdr->name_offset +
+	    (unsigned long)phdr->name_length > ctx->param_bytes)
+		return NULL;
+	ctx->curr = (char *)&phdr + phdr->name_offset;
+	ctx->bytes_remaining = phdr->name_length;
+	return parser_string_get(ctx->curr, phdr->name_length);
+}
+
+static int visorbus_configure(struct controlvm_message *inmsg,
+			      struct parser_context *parser_ctx)
+{
+	struct controlvm_message_packet *cmd = &inmsg->cmd;
+	u32 bus_no;
+	struct visor_device *bus_info;
+	int err = 0;
+
+	bus_no = cmd->configure_bus.bus_no;
+	bus_info = visorbus_get_device_by_id(bus_no, BUS_ROOT_DEVICE, NULL);
+	if (!bus_info) {
+		err = -EINVAL;
+		goto err_respond;
+	}
+	if (bus_info->state.created == 0) {
+		err = -EINVAL;
+		goto err_respond;
+	}
+	if (bus_info->pending_msg_hdr) {
+		err = -EIO;
+		goto err_respond;
+	}
+	err = visorchannel_set_clientpartition(bus_info->visorchannel,
+					       cmd->configure_bus.guest_handle);
+	if (err)
+		goto err_respond;
+	if (parser_ctx) {
+		const guid_t *partition_guid = parser_id_get(parser_ctx);
+
+		guid_copy(&bus_info->partition_guid, partition_guid);
+		bus_info->name = parser_name_get(parser_ctx);
+	}
+	if (inmsg->hdr.flags.response_expected == 1)
+		controlvm_responder(inmsg->hdr.id, &inmsg->hdr, err);
+	return 0;
+
+err_respond:
+	dev_err(&chipset_dev->acpi_device->dev,
+		"%s exited with err: %d\n", __func__, err);
+	if (inmsg->hdr.flags.response_expected == 1)
+		controlvm_responder(inmsg->hdr.id, &inmsg->hdr, err);
+	return err;
+}
+
+static int visorbus_device_create(struct controlvm_message *inmsg)
+{
+	struct controlvm_message_packet *cmd = &inmsg->cmd;
+	struct controlvm_message_header *pmsg_hdr;
+	u32 bus_no = cmd->create_device.bus_no;
+	u32 dev_no = cmd->create_device.dev_no;
+	struct visor_device *dev_info;
+	struct visor_device *bus_info;
+	struct visorchannel *visorchannel;
+	int err;
+
+	bus_info = visorbus_get_device_by_id(bus_no, BUS_ROOT_DEVICE, NULL);
+	if (!bus_info) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"failed to get bus by id: %d\n", bus_no);
+		err = -ENODEV;
+		goto err_respond;
+	}
+	if (bus_info->state.created == 0) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"bus not created, id: %d\n", bus_no);
+		err = -EINVAL;
+		goto err_respond;
+	}
+	dev_info = visorbus_get_device_by_id(bus_no, dev_no, NULL);
+	if (dev_info && dev_info->state.created == 1) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"failed to get bus by id: %d/%d\n", bus_no, dev_no);
+		err = -EEXIST;
+		goto err_respond;
+	}
+
+	dev_info = kzalloc(sizeof(*dev_info), GFP_KERNEL);
+	if (!dev_info) {
+		err = -ENOMEM;
+		goto err_respond;
+	}
+	dev_info->chipset_bus_no = bus_no;
+	dev_info->chipset_dev_no = dev_no;
+	guid_copy(&dev_info->inst, &cmd->create_device.dev_inst_guid);
+	dev_info->device.parent = &bus_info->device;
+	visorchannel = visorchannel_create(cmd->create_device.channel_addr,
+					   GFP_KERNEL,
+					   &cmd->create_device.data_type_guid,
+					   true);
+	if (!visorchannel) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"failed to create visorchannel: %d/%d\n",
+			bus_no, dev_no);
+		err = -ENOMEM;
+		goto err_free_dev_info;
+	}
+	dev_info->visorchannel = visorchannel;
+	guid_copy(&dev_info->channel_type_guid,
+		  &cmd->create_device.data_type_guid);
+	if (guid_equal(&cmd->create_device.data_type_guid,
+		       &visor_vhba_channel_guid)) {
+		err = save_crash_message(inmsg, CRASH_DEV);
+		if (err)
+			goto err_destroy_visorchannel;
+	}
+	if (inmsg->hdr.flags.response_expected == 1) {
+		pmsg_hdr = kzalloc(sizeof(*pmsg_hdr), GFP_KERNEL);
+		if (!pmsg_hdr) {
+			err = -ENOMEM;
+			goto err_destroy_visorchannel;
+		}
+		memcpy(pmsg_hdr, &inmsg->hdr,
+		       sizeof(struct controlvm_message_header));
+		dev_info->pending_msg_hdr = pmsg_hdr;
+	}
+	/* create_visor_device will send response */
+	err = create_visor_device(dev_info);
+	if (err)
+		goto err_destroy_visorchannel;
+
+	return 0;
+
+err_destroy_visorchannel:
+	visorchannel_destroy(visorchannel);
+
+err_free_dev_info:
+	kfree(dev_info);
+
+err_respond:
+	if (inmsg->hdr.flags.response_expected == 1)
+		controlvm_responder(inmsg->hdr.id, &inmsg->hdr, err);
+	return err;
+}
+
+static int visorbus_device_changestate(struct controlvm_message *inmsg)
+{
+	struct controlvm_message_packet *cmd = &inmsg->cmd;
+	struct controlvm_message_header *pmsg_hdr;
+	u32 bus_no = cmd->device_change_state.bus_no;
+	u32 dev_no = cmd->device_change_state.dev_no;
+	struct visor_segment_state state = cmd->device_change_state.state;
+	struct visor_device *dev_info;
+	int err = 0;
+
+	dev_info = visorbus_get_device_by_id(bus_no, dev_no, NULL);
+	if (!dev_info) {
+		err = -ENODEV;
+		goto err_respond;
+	}
+	if (dev_info->state.created == 0) {
+		err = -EINVAL;
+		goto err_respond;
+	}
+	if (dev_info->pending_msg_hdr) {
+		/* only non-NULL if dev is still waiting on a response */
+		err = -EIO;
+		goto err_respond;
+	}
+
+	if (inmsg->hdr.flags.response_expected == 1) {
+		pmsg_hdr = kzalloc(sizeof(*pmsg_hdr), GFP_KERNEL);
+		if (!pmsg_hdr) {
+			err = -ENOMEM;
+			goto err_respond;
+		}
+		memcpy(pmsg_hdr, &inmsg->hdr,
+		       sizeof(struct controlvm_message_header));
+		dev_info->pending_msg_hdr = pmsg_hdr;
+	}
+	if (state.alive == segment_state_running.alive &&
+	    state.operating == segment_state_running.operating)
+		/* Response will be sent from visorchipset_device_resume */
+		err = visorchipset_device_resume(dev_info);
+	/* ServerNotReady / ServerLost / SegmentStateStandby */
+	else if (state.alive == segment_state_standby.alive &&
+		 state.operating == segment_state_standby.operating)
+		/*
+		 * technically this is standby case where server is lost.
+		 * Response will be sent from visorchipset_device_pause.
+		 */
+		err = visorchipset_device_pause(dev_info);
+	if (err)
+		goto err_respond;
+	return 0;
+
+err_respond:
+	dev_err(&chipset_dev->acpi_device->dev, "failed: %d\n", err);
+	if (inmsg->hdr.flags.response_expected == 1)
+		controlvm_responder(inmsg->hdr.id, &inmsg->hdr, err);
+	return err;
+}
+
+static int visorbus_device_destroy(struct controlvm_message *inmsg)
+{
+	struct controlvm_message_packet *cmd = &inmsg->cmd;
+	struct controlvm_message_header *pmsg_hdr;
+	u32 bus_no = cmd->destroy_device.bus_no;
+	u32 dev_no = cmd->destroy_device.dev_no;
+	struct visor_device *dev_info;
+	int err;
+
+	dev_info = visorbus_get_device_by_id(bus_no, dev_no, NULL);
+	if (!dev_info) {
+		err = -ENODEV;
+		goto err_respond;
+	}
+	if (dev_info->state.created == 0) {
+		err = -EINVAL;
+		goto err_respond;
+	}
+	if (dev_info->pending_msg_hdr) {
+		/* only non-NULL if dev is still waiting on a response */
+		err = -EIO;
+		goto err_respond;
+	}
+	if (inmsg->hdr.flags.response_expected == 1) {
+		pmsg_hdr = kzalloc(sizeof(*pmsg_hdr), GFP_KERNEL);
+		if (!pmsg_hdr) {
+			err = -ENOMEM;
+			goto err_respond;
+		}
+
+		memcpy(pmsg_hdr, &inmsg->hdr,
+		       sizeof(struct controlvm_message_header));
+		dev_info->pending_msg_hdr = pmsg_hdr;
+	}
+	kfree(dev_info->name);
+	remove_visor_device(dev_info);
+	return 0;
+
+err_respond:
+	if (inmsg->hdr.flags.response_expected == 1)
+		controlvm_responder(inmsg->hdr.id, &inmsg->hdr, err);
+	return err;
+}
+
+/*
+ * The general parahotplug flow works as follows. The visorchipset receives
+ * a DEVICE_CHANGESTATE message from Command specifying a physical device
+ * to enable or disable. The CONTROLVM message handler calls
+ * parahotplug_process_message, which then adds the message to a global list
+ * and kicks off a udev event which causes a user level script to enable or
+ * disable the specified device. The udev script then writes to
+ * /sys/devices/platform/visorchipset/parahotplug, which causes the
+ * parahotplug store functions to get called, at which point the
+ * appropriate CONTROLVM message is retrieved from the list and responded to.
+ */
+
+#define PARAHOTPLUG_TIMEOUT_MS 2000
+
+/*
+ * parahotplug_next_id() - generate unique int to match an outstanding
+ *                         CONTROLVM message with a udev script /sys
+ *                         response
+ *
+ * Return: a unique integer value
+ */
+static int parahotplug_next_id(void)
+{
+	static atomic_t id = ATOMIC_INIT(0);
+
+	return atomic_inc_return(&id);
+}
+
+/*
+ * parahotplug_next_expiration() - returns the time (in jiffies) when a
+ *                                 CONTROLVM message on the list should expire
+ *                                 -- PARAHOTPLUG_TIMEOUT_MS in the future
+ *
+ * Return: expected expiration time (in jiffies)
+ */
+static unsigned long parahotplug_next_expiration(void)
+{
+	return jiffies + msecs_to_jiffies(PARAHOTPLUG_TIMEOUT_MS);
+}
+
+/*
+ * parahotplug_request_create() - create a parahotplug_request, which is
+ *                                basically a wrapper for a CONTROLVM_MESSAGE
+ *                                that we can stick on a list
+ * @msg: the message to insert in the request
+ *
+ * Return: the request containing the provided message
+ */
+static struct parahotplug_request *parahotplug_request_create(
+						struct controlvm_message *msg)
+{
+	struct parahotplug_request *req;
+
+	req = kmalloc(sizeof(*req), GFP_KERNEL);
+	if (!req)
+		return NULL;
+	req->id = parahotplug_next_id();
+	req->expiration = parahotplug_next_expiration();
+	req->msg = *msg;
+	return req;
+}
+
+/*
+ * parahotplug_request_destroy() - free a parahotplug_request
+ * @req: the request to deallocate
+ */
+static void parahotplug_request_destroy(struct parahotplug_request *req)
+{
+	kfree(req);
+}
+
+static LIST_HEAD(parahotplug_request_list);
+/* lock for above */
+static DEFINE_SPINLOCK(parahotplug_request_list_lock);
+
+/*
+ * parahotplug_request_complete() - mark request as complete
+ * @id:     the id of the request
+ * @active: indicates whether the request is assigned to active partition
+ *
+ * Called from the /sys handler, which means the user script has
+ * finished the enable/disable. Find the matching identifier, and
+ * respond to the CONTROLVM message with success.
+ *
+ * Return: 0 on success or -EINVAL on failure
+ */
+static int parahotplug_request_complete(int id, u16 active)
+{
+	struct list_head *pos;
+	struct list_head *tmp;
+	struct parahotplug_request *req;
+
+	spin_lock(&parahotplug_request_list_lock);
+	/* Look for a request matching "id". */
+	list_for_each_safe(pos, tmp, &parahotplug_request_list) {
+		req = list_entry(pos, struct parahotplug_request, list);
+		if (req->id == id) {
+			/*
+			 * Found a match. Remove it from the list and
+			 * respond.
+			 */
+			list_del(pos);
+			spin_unlock(&parahotplug_request_list_lock);
+			req->msg.cmd.device_change_state.state.active = active;
+			if (req->msg.hdr.flags.response_expected)
+				controlvm_respond(
+				       &req->msg.hdr, CONTROLVM_RESP_SUCCESS,
+				       &req->msg.cmd.device_change_state.state);
+			parahotplug_request_destroy(req);
+			return 0;
+		}
+	}
+	spin_unlock(&parahotplug_request_list_lock);
+	return -EINVAL;
+}
+
+/*
+ * devicedisabled_store() - disables the hotplug device
+ * @dev:   sysfs interface variable not utilized in this function
+ * @attr:  sysfs interface variable not utilized in this function
+ * @buf:   buffer containing the device id
+ * @count: the size of the buffer
+ *
+ * The parahotplug/devicedisabled interface gets called by our support script
+ * when an SR-IOV device has been shut down. The ID is passed to the script
+ * and then passed back when the device has been removed.
+ *
+ * Return: the size of the buffer for success or negative for error
+ */
+static ssize_t devicedisabled_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	unsigned int id;
+	int err;
+
+	if (kstrtouint(buf, 10, &id))
+		return -EINVAL;
+	err = parahotplug_request_complete(id, 0);
+	if (err < 0)
+		return err;
+	return count;
+}
+static DEVICE_ATTR_WO(devicedisabled);
+
+/*
+ * deviceenabled_store() - enables the hotplug device
+ * @dev:   sysfs interface variable not utilized in this function
+ * @attr:  sysfs interface variable not utilized in this function
+ * @buf:   buffer containing the device id
+ * @count: the size of the buffer
+ *
+ * The parahotplug/deviceenabled interface gets called by our support script
+ * when an SR-IOV device has been recovered. The ID is passed to the script
+ * and then passed back when the device has been brought back up.
+ *
+ * Return: the size of the buffer for success or negative for error
+ */
+static ssize_t deviceenabled_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t count)
+{
+	unsigned int id;
+
+	if (kstrtouint(buf, 10, &id))
+		return -EINVAL;
+	parahotplug_request_complete(id, 1);
+	return count;
+}
+static DEVICE_ATTR_WO(deviceenabled);
+
+static struct attribute *visorchipset_install_attrs[] = {
+	&dev_attr_toolaction.attr,
+	&dev_attr_boottotool.attr,
+	&dev_attr_error.attr,
+	&dev_attr_textid.attr,
+	&dev_attr_remaining_steps.attr,
+	NULL
+};
+
+static const struct attribute_group visorchipset_install_group = {
+	.name = "install",
+	.attrs = visorchipset_install_attrs
+};
+
+static struct attribute *visorchipset_parahotplug_attrs[] = {
+	&dev_attr_devicedisabled.attr,
+	&dev_attr_deviceenabled.attr,
+	NULL
+};
+
+static const struct attribute_group visorchipset_parahotplug_group = {
+	.name = "parahotplug",
+	.attrs = visorchipset_parahotplug_attrs
+};
+
+static const struct attribute_group *visorchipset_dev_groups[] = {
+	&visorchipset_install_group,
+	&visorchipset_parahotplug_group,
+	NULL
+};
+
+/*
+ * parahotplug_request_kickoff() - initiate parahotplug request
+ * @req: the request to initiate
+ *
+ * Cause uevent to run the user level script to do the disable/enable specified
+ * in the parahotplug_request.
+ */
+static int parahotplug_request_kickoff(struct parahotplug_request *req)
+{
+	struct controlvm_message_packet *cmd = &req->msg.cmd;
+	char env_cmd[40], env_id[40], env_state[40], env_bus[40], env_dev[40],
+	     env_func[40];
+	char *envp[] = { env_cmd, env_id, env_state, env_bus, env_dev,
+			 env_func, NULL
+	};
+
+	sprintf(env_cmd, "VISOR_PARAHOTPLUG=1");
+	sprintf(env_id, "VISOR_PARAHOTPLUG_ID=%d", req->id);
+	sprintf(env_state, "VISOR_PARAHOTPLUG_STATE=%d",
+		cmd->device_change_state.state.active);
+	sprintf(env_bus, "VISOR_PARAHOTPLUG_BUS=%d",
+		cmd->device_change_state.bus_no);
+	sprintf(env_dev, "VISOR_PARAHOTPLUG_DEVICE=%d",
+		cmd->device_change_state.dev_no >> 3);
+	sprintf(env_func, "VISOR_PARAHOTPLUG_FUNCTION=%d",
+		cmd->device_change_state.dev_no & 0x7);
+	return kobject_uevent_env(&chipset_dev->acpi_device->dev.kobj,
+				  KOBJ_CHANGE, envp);
+}
+
+/*
+ * parahotplug_process_message() - enables or disables a PCI device by kicking
+ *                                 off a udev script
+ * @inmsg: the message indicating whether to enable or disable
+ */
+static int parahotplug_process_message(struct controlvm_message *inmsg)
+{
+	struct parahotplug_request *req;
+	int err;
+
+	req = parahotplug_request_create(inmsg);
+	if (!req)
+		return -ENOMEM;
+	/*
+	 * For enable messages, just respond with success right away, we don't
+	 * need to wait to see if the enable was successful.
+	 */
+	if (inmsg->cmd.device_change_state.state.active) {
+		err = parahotplug_request_kickoff(req);
+		if (err)
+			goto err_respond;
+		controlvm_respond(&inmsg->hdr, CONTROLVM_RESP_SUCCESS,
+				  &inmsg->cmd.device_change_state.state);
+		parahotplug_request_destroy(req);
+		return 0;
+	}
+	/*
+	 * For disable messages, add the request to the request list before
+	 * kicking off the udev script. It won't get responded to until the
+	 * script has indicated it's done.
+	 */
+	spin_lock(&parahotplug_request_list_lock);
+	list_add_tail(&req->list, &parahotplug_request_list);
+	spin_unlock(&parahotplug_request_list_lock);
+	err = parahotplug_request_kickoff(req);
+	if (err)
+		goto err_respond;
+	return 0;
+
+err_respond:
+	controlvm_respond(&inmsg->hdr, err,
+			  &inmsg->cmd.device_change_state.state);
+	return err;
+}
+
+/*
+ * chipset_ready_uevent() - sends chipset_ready action
+ *
+ * Send ACTION=online for DEVPATH=/sys/devices/platform/visorchipset.
+ *
+ * Return: 0 on success, negative on failure
+ */
+static int chipset_ready_uevent(struct controlvm_message_header *msg_hdr)
+{
+	int res;
+
+	res = kobject_uevent(&chipset_dev->acpi_device->dev.kobj, KOBJ_ONLINE);
+	if (msg_hdr->flags.response_expected)
+		controlvm_respond(msg_hdr, res, NULL);
+	return res;
+}
+
+/*
+ * chipset_selftest_uevent() - sends chipset_selftest action
+ *
+ * Send ACTION=online for DEVPATH=/sys/devices/platform/visorchipset.
+ *
+ * Return: 0 on success, negative on failure
+ */
+static int chipset_selftest_uevent(struct controlvm_message_header *msg_hdr)
+{
+	char env_selftest[20];
+	char *envp[] = { env_selftest, NULL };
+	int res;
+
+	sprintf(env_selftest, "SPARSP_SELFTEST=%d", 1);
+	res = kobject_uevent_env(&chipset_dev->acpi_device->dev.kobj,
+				 KOBJ_CHANGE, envp);
+	if (msg_hdr->flags.response_expected)
+		controlvm_respond(msg_hdr, res, NULL);
+	return res;
+}
+
+/*
+ * chipset_notready_uevent() - sends chipset_notready action
+ *
+ * Send ACTION=offline for DEVPATH=/sys/devices/platform/visorchipset.
+ *
+ * Return: 0 on success, negative on failure
+ */
+static int chipset_notready_uevent(struct controlvm_message_header *msg_hdr)
+{
+	int res = kobject_uevent(&chipset_dev->acpi_device->dev.kobj,
+				 KOBJ_OFFLINE);
+
+	if (msg_hdr->flags.response_expected)
+		controlvm_respond(msg_hdr, res, NULL);
+	return res;
+}
+
+static int unisys_vmcall(unsigned long tuple, unsigned long param)
+{
+	int result = 0;
+	unsigned int cpuid_eax, cpuid_ebx, cpuid_ecx, cpuid_edx;
+	unsigned long reg_ebx;
+	unsigned long reg_ecx;
+
+	reg_ebx = param & 0xFFFFFFFF;
+	reg_ecx = param >> 32;
+	cpuid(0x00000001, &cpuid_eax, &cpuid_ebx, &cpuid_ecx, &cpuid_edx);
+	if (!(cpuid_ecx & 0x80000000))
+		return -EPERM;
+	__asm__ __volatile__(".byte 0x00f, 0x001, 0x0c1" : "=a"(result) :
+			     "a"(tuple), "b"(reg_ebx), "c"(reg_ecx));
+	if (result)
+		goto error;
+	return 0;
+
+/* Need to convert from VMCALL error codes to Linux */
+error:
+	switch (result) {
+	case VMCALL_RESULT_INVALID_PARAM:
+		return -EINVAL;
+	case VMCALL_RESULT_DATA_UNAVAILABLE:
+		return -ENODEV;
+	default:
+		return -EFAULT;
+	}
+}
+
+static int controlvm_channel_create(struct visorchipset_device *dev)
+{
+	struct visorchannel *chan;
+	u64 addr;
+	int err;
+
+	err = unisys_vmcall(VMCALL_CONTROLVM_ADDR,
+			    virt_to_phys(&dev->controlvm_params));
+	if (err)
+		return err;
+	addr = dev->controlvm_params.address;
+	chan = visorchannel_create(addr, GFP_KERNEL,
+				   &visor_controlvm_channel_guid, true);
+	if (!chan)
+		return -ENOMEM;
+	dev->controlvm_channel = chan;
+	return 0;
+}
+
+static void setup_crash_devices_work_queue(struct work_struct *work)
+{
+	struct controlvm_message local_crash_bus_msg;
+	struct controlvm_message local_crash_dev_msg;
+	struct controlvm_message msg;
+	u32 local_crash_msg_offset;
+	u16 local_crash_msg_count;
+
+	/* send init chipset msg */
+	msg.hdr.id = CONTROLVM_CHIPSET_INIT;
+	msg.cmd.init_chipset.bus_count = 23;
+	msg.cmd.init_chipset.switch_count = 0;
+	chipset_init(&msg);
+	/* get saved message count */
+	if (visorchannel_read(chipset_dev->controlvm_channel,
+			      offsetof(struct visor_controlvm_channel,
+				       saved_crash_message_count),
+			      &local_crash_msg_count, sizeof(u16)) < 0) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"failed to read channel\n");
+		return;
+	}
+	if (local_crash_msg_count != CONTROLVM_CRASHMSG_MAX) {
+		dev_err(&chipset_dev->acpi_device->dev, "invalid count\n");
+		return;
+	}
+	/* get saved crash message offset */
+	if (visorchannel_read(chipset_dev->controlvm_channel,
+			      offsetof(struct visor_controlvm_channel,
+				       saved_crash_message_offset),
+			      &local_crash_msg_offset, sizeof(u32)) < 0) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"failed to read channel\n");
+		return;
+	}
+	/* read create device message for storage bus offset */
+	if (visorchannel_read(chipset_dev->controlvm_channel,
+			      local_crash_msg_offset,
+			      &local_crash_bus_msg,
+			      sizeof(struct controlvm_message)) < 0) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"failed to read channel\n");
+		return;
+	}
+	/* read create device message for storage device */
+	if (visorchannel_read(chipset_dev->controlvm_channel,
+			      local_crash_msg_offset +
+			      sizeof(struct controlvm_message),
+			      &local_crash_dev_msg,
+			      sizeof(struct controlvm_message)) < 0) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"failed to read channel\n");
+		return;
+	}
+	/* reuse IOVM create bus message */
+	if (!local_crash_bus_msg.cmd.create_bus.channel_addr) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"no valid create_bus message\n");
+		return;
+	}
+	visorbus_create(&local_crash_bus_msg);
+	/* reuse create device message for storage device */
+	if (!local_crash_dev_msg.cmd.create_device.channel_addr) {
+		dev_err(&chipset_dev->acpi_device->dev,
+			"no valid create_device message\n");
+		return;
+	}
+	visorbus_device_create(&local_crash_dev_msg);
+}
+
+void visorbus_response(struct visor_device *bus_info, int response,
+		       int controlvm_id)
+{
+	if (!bus_info->pending_msg_hdr)
+		return;
+
+	controlvm_responder(controlvm_id, bus_info->pending_msg_hdr, response);
+	kfree(bus_info->pending_msg_hdr);
+	bus_info->pending_msg_hdr = NULL;
+}
+
+void visorbus_device_changestate_response(struct visor_device *dev_info,
+					  int response,
+					  struct visor_segment_state state)
+{
+	if (!dev_info->pending_msg_hdr)
+		return;
+
+	device_changestate_responder(CONTROLVM_DEVICE_CHANGESTATE, dev_info,
+				     response, state);
+	kfree(dev_info->pending_msg_hdr);
+	dev_info->pending_msg_hdr = NULL;
+}
+
+static void parser_done(struct parser_context *ctx)
+{
+	chipset_dev->controlvm_payload_bytes_buffered -= ctx->param_bytes;
+	kfree(ctx);
+}
+
+static struct parser_context *parser_init_stream(u64 addr, u32 bytes,
+						 bool *retry)
+{
+	unsigned long allocbytes;
+	struct parser_context *ctx;
+	void *mapping;
+
+	*retry = false;
+	/* alloc an extra byte to ensure payload is \0 terminated */
+	allocbytes = (unsigned long)bytes + 1 + (sizeof(struct parser_context) -
+		     sizeof(struct visor_controlvm_parameters_header));
+	if ((chipset_dev->controlvm_payload_bytes_buffered + bytes) >
+	     MAX_CONTROLVM_PAYLOAD_BYTES) {
+		*retry = true;
+		return NULL;
+	}
+	ctx = kzalloc(allocbytes, GFP_KERNEL);
+	if (!ctx) {
+		*retry = true;
+		return NULL;
+	}
+	ctx->allocbytes = allocbytes;
+	ctx->param_bytes = bytes;
+	mapping = memremap(addr, bytes, MEMREMAP_WB);
+	if (!mapping)
+		goto err_finish_ctx;
+	memcpy(&ctx->data, mapping, bytes);
+	memunmap(mapping);
+	ctx->byte_stream = true;
+	chipset_dev->controlvm_payload_bytes_buffered += ctx->param_bytes;
+	return ctx;
+
+err_finish_ctx:
+	kfree(ctx);
+	return NULL;
+}
+
+/*
+ * handle_command() - process a controlvm message
+ * @inmsg:        the message to process
+ * @channel_addr: address of the controlvm channel
+ *
+ * Return:
+ *	0	- Successfully processed the message
+ *	-EAGAIN - ControlVM message was not processed and should be retried
+ *		  reading the next controlvm message; a scenario where this can
+ *		  occur is when we need to throttle the allocation of memory in
+ *		  which to copy out controlvm payload data.
+ *	< 0	- error: ControlVM message was processed but an error occurred.
+ */
+static int handle_command(struct controlvm_message inmsg, u64 channel_addr)
+{
+	struct controlvm_message_packet *cmd = &inmsg.cmd;
+	u64 parm_addr;
+	u32 parm_bytes;
+	struct parser_context *parser_ctx = NULL;
+	struct controlvm_message ackmsg;
+	int err = 0;
+
+	/* create parsing context if necessary */
+	parm_addr = channel_addr + inmsg.hdr.payload_vm_offset;
+	parm_bytes = inmsg.hdr.payload_bytes;
+	/*
+	 * Parameter and channel addresses within test messages actually lie
+	 * within our OS-controlled memory. We need to know that, because it
+	 * makes a difference in how we compute the virtual address.
+	 */
+	if (parm_bytes) {
+		bool retry;
+
+		parser_ctx = parser_init_stream(parm_addr, parm_bytes, &retry);
+		if (!parser_ctx && retry)
+			return -EAGAIN;
+	}
+	controlvm_init_response(&ackmsg, &inmsg.hdr, CONTROLVM_RESP_SUCCESS);
+	err = visorchannel_signalinsert(chipset_dev->controlvm_channel,
+					CONTROLVM_QUEUE_ACK, &ackmsg);
+	if (err)
+		return err;
+	switch (inmsg.hdr.id) {
+	case CONTROLVM_CHIPSET_INIT:
+		err = chipset_init(&inmsg);
+		break;
+	case CONTROLVM_BUS_CREATE:
+		err = visorbus_create(&inmsg);
+		break;
+	case CONTROLVM_BUS_DESTROY:
+		err = visorbus_destroy(&inmsg);
+		break;
+	case CONTROLVM_BUS_CONFIGURE:
+		err = visorbus_configure(&inmsg, parser_ctx);
+		break;
+	case CONTROLVM_DEVICE_CREATE:
+		err = visorbus_device_create(&inmsg);
+		break;
+	case CONTROLVM_DEVICE_CHANGESTATE:
+		if (cmd->device_change_state.flags.phys_device) {
+			err = parahotplug_process_message(&inmsg);
+		} else {
+			/*
+			 * save the hdr and cmd structures for later use when
+			 * sending back the response to Command
+			 */
+			err = visorbus_device_changestate(&inmsg);
+			break;
+		}
+		break;
+	case CONTROLVM_DEVICE_DESTROY:
+		err = visorbus_device_destroy(&inmsg);
+		break;
+	case CONTROLVM_DEVICE_CONFIGURE:
+		/* no op just send a respond that we passed */
+		if (inmsg.hdr.flags.response_expected)
+			controlvm_respond(&inmsg.hdr, CONTROLVM_RESP_SUCCESS,
+					  NULL);
+		break;
+	case CONTROLVM_CHIPSET_READY:
+		err = chipset_ready_uevent(&inmsg.hdr);
+		break;
+	case CONTROLVM_CHIPSET_SELFTEST:
+		err = chipset_selftest_uevent(&inmsg.hdr);
+		break;
+	case CONTROLVM_CHIPSET_STOP:
+		err = chipset_notready_uevent(&inmsg.hdr);
+		break;
+	default:
+		err = -ENOMSG;
+		if (inmsg.hdr.flags.response_expected)
+			controlvm_respond(&inmsg.hdr,
+					  -CONTROLVM_RESP_ID_UNKNOWN, NULL);
+		break;
+	}
+	if (parser_ctx) {
+		parser_done(parser_ctx);
+		parser_ctx = NULL;
+	}
+	return err;
+}
+
+/*
+ * read_controlvm_event() - retreives the next message from the
+ *                          CONTROLVM_QUEUE_EVENT queue in the controlvm
+ *                          channel
+ * @msg: pointer to the retrieved message
+ *
+ * Return: 0 if valid message was retrieved or -error
+ */
+static int read_controlvm_event(struct controlvm_message *msg)
+{
+	int err = visorchannel_signalremove(chipset_dev->controlvm_channel,
+					    CONTROLVM_QUEUE_EVENT, msg);
+
+	if (err)
+		return err;
+	/* got a message */
+	if (msg->hdr.flags.test_message == 1)
+		return -EINVAL;
+	return 0;
+}
+
+/*
+ * parahotplug_process_list() - remove any request from the list that's been on
+ *                              there too long and respond with an error
+ */
+static void parahotplug_process_list(void)
+{
+	struct list_head *pos;
+	struct list_head *tmp;
+
+	spin_lock(&parahotplug_request_list_lock);
+	list_for_each_safe(pos, tmp, &parahotplug_request_list) {
+		struct parahotplug_request *req =
+		    list_entry(pos, struct parahotplug_request, list);
+
+		if (!time_after_eq(jiffies, req->expiration))
+			continue;
+		list_del(pos);
+		if (req->msg.hdr.flags.response_expected)
+			controlvm_respond(
+				&req->msg.hdr,
+				CONTROLVM_RESP_DEVICE_UDEV_TIMEOUT,
+				&req->msg.cmd.device_change_state.state);
+		parahotplug_request_destroy(req);
+	}
+	spin_unlock(&parahotplug_request_list_lock);
+}
+
+static void controlvm_periodic_work(struct work_struct *work)
+{
+	struct controlvm_message inmsg;
+	int count = 0;
+	int err;
+
+	/* Drain the RESPONSE queue make it empty */
+	do {
+		err = visorchannel_signalremove(chipset_dev->controlvm_channel,
+						CONTROLVM_QUEUE_RESPONSE,
+						&inmsg);
+	} while ((!err) && (++count < CONTROLVM_MESSAGE_MAX));
+	if (err != -EAGAIN)
+		goto schedule_out;
+	if (chipset_dev->controlvm_pending_msg_valid) {
+		/*
+		 * we throttled processing of a prior msg, so try to process
+		 * it again rather than reading a new one
+		 */
+		inmsg = chipset_dev->controlvm_pending_msg;
+		chipset_dev->controlvm_pending_msg_valid = false;
+		err = 0;
+	} else {
+		err = read_controlvm_event(&inmsg);
+	}
+	while (!err) {
+		chipset_dev->most_recent_message_jiffies = jiffies;
+		err = handle_command(inmsg,
+				     visorchannel_get_physaddr
+				     (chipset_dev->controlvm_channel));
+		if (err == -EAGAIN) {
+			chipset_dev->controlvm_pending_msg = inmsg;
+			chipset_dev->controlvm_pending_msg_valid = true;
+			break;
+		}
+
+		err = read_controlvm_event(&inmsg);
+	}
+	/* parahotplug_worker */
+	parahotplug_process_list();
+
+/*
+ * The controlvm messages are sent in a bulk. If we start receiving messages, we
+ * want the polling to be fast. If we do not receive any message for
+ * MIN_IDLE_SECONDS, we can slow down the polling.
+ */
+schedule_out:
+	if (time_after(jiffies, chipset_dev->most_recent_message_jiffies +
+				(HZ * MIN_IDLE_SECONDS))) {
+		/*
+		 * it's been longer than MIN_IDLE_SECONDS since we processed
+		 * our last controlvm message; slow down the polling
+		 */
+		if (chipset_dev->poll_jiffies != POLLJIFFIES_CONTROLVM_SLOW)
+			chipset_dev->poll_jiffies = POLLJIFFIES_CONTROLVM_SLOW;
+	} else {
+		if (chipset_dev->poll_jiffies != POLLJIFFIES_CONTROLVM_FAST)
+			chipset_dev->poll_jiffies = POLLJIFFIES_CONTROLVM_FAST;
+	}
+	schedule_delayed_work(&chipset_dev->periodic_controlvm_work,
+			      chipset_dev->poll_jiffies);
+}
+
+static int visorchipset_init(struct acpi_device *acpi_device)
+{
+	int err = -ENODEV;
+	struct visorchannel *controlvm_channel;
+
+	chipset_dev = kzalloc(sizeof(*chipset_dev), GFP_KERNEL);
+	if (!chipset_dev)
+		goto error;
+	err = controlvm_channel_create(chipset_dev);
+	if (err)
+		goto error_free_chipset_dev;
+	acpi_device->driver_data = chipset_dev;
+	chipset_dev->acpi_device = acpi_device;
+	chipset_dev->poll_jiffies = POLLJIFFIES_CONTROLVM_FAST;
+	err = sysfs_create_groups(&chipset_dev->acpi_device->dev.kobj,
+				  visorchipset_dev_groups);
+	if (err < 0)
+		goto error_destroy_channel;
+	controlvm_channel = chipset_dev->controlvm_channel;
+	if (!visor_check_channel(visorchannel_get_header(controlvm_channel),
+				 &chipset_dev->acpi_device->dev,
+				 &visor_controlvm_channel_guid,
+				 "controlvm",
+				 sizeof(struct visor_controlvm_channel),
+				 VISOR_CONTROLVM_CHANNEL_VERSIONID,
+				 VISOR_CHANNEL_SIGNATURE))
+		goto error_delete_groups;
+	/* if booting in a crash kernel */
+	if (is_kdump_kernel())
+		INIT_DELAYED_WORK(&chipset_dev->periodic_controlvm_work,
+				  setup_crash_devices_work_queue);
+	else
+		INIT_DELAYED_WORK(&chipset_dev->periodic_controlvm_work,
+				  controlvm_periodic_work);
+	chipset_dev->most_recent_message_jiffies = jiffies;
+	chipset_dev->poll_jiffies = POLLJIFFIES_CONTROLVM_FAST;
+	schedule_delayed_work(&chipset_dev->periodic_controlvm_work,
+			      chipset_dev->poll_jiffies);
+	err = visorbus_init();
+	if (err < 0)
+		goto error_cancel_work;
+	return 0;
+
+error_cancel_work:
+	cancel_delayed_work_sync(&chipset_dev->periodic_controlvm_work);
+
+error_delete_groups:
+	sysfs_remove_groups(&chipset_dev->acpi_device->dev.kobj,
+			    visorchipset_dev_groups);
+
+error_destroy_channel:
+	visorchannel_destroy(chipset_dev->controlvm_channel);
+
+error_free_chipset_dev:
+	kfree(chipset_dev);
+
+error:
+	dev_err(&acpi_device->dev, "failed with error %d\n", err);
+	return err;
+}
+
+static int visorchipset_exit(struct acpi_device *acpi_device)
+{
+	visorbus_exit();
+	cancel_delayed_work_sync(&chipset_dev->periodic_controlvm_work);
+	sysfs_remove_groups(&chipset_dev->acpi_device->dev.kobj,
+			    visorchipset_dev_groups);
+	visorchannel_destroy(chipset_dev->controlvm_channel);
+	kfree(chipset_dev);
+	return 0;
+}
+
+static const struct acpi_device_id unisys_device_ids[] = {
+	{"PNP0A07", 0},
+	{"", 0},
+};
+
+static struct acpi_driver unisys_acpi_driver = {
+	.name = "unisys_acpi",
+	.class = "unisys_acpi_class",
+	.owner = THIS_MODULE,
+	.ids = unisys_device_ids,
+	.ops = {
+		.add = visorchipset_init,
+		.remove = visorchipset_exit,
+	},
+};
+
+MODULE_DEVICE_TABLE(acpi, unisys_device_ids);
+
+static __init int visorutil_spar_detect(void)
+{
+	unsigned int eax, ebx, ecx, edx;
+
+	if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
+		/* check the ID */
+		cpuid(UNISYS_VISOR_LEAF_ID, &eax, &ebx, &ecx, &edx);
+		return  (ebx == UNISYS_VISOR_ID_EBX) &&
+			(ecx == UNISYS_VISOR_ID_ECX) &&
+			(edx == UNISYS_VISOR_ID_EDX);
+	}
+	return 0;
+}
+
+static int __init init_unisys(void)
+{
+	int result;
+
+	if (!visorutil_spar_detect())
+		return -ENODEV;
+	result = acpi_bus_register_driver(&unisys_acpi_driver);
+	if (result)
+		return -ENODEV;
+	pr_info("Unisys Visorchipset Driver Loaded.\n");
+	return 0;
+};
+
+static void __exit exit_unisys(void)
+{
+	acpi_bus_unregister_driver(&unisys_acpi_driver);
+}
+
+module_init(init_unisys);
+module_exit(exit_unisys);
+
+MODULE_AUTHOR("Unisys");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("s-Par visorbus driver for virtual device buses");