// 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 = {
                .hdr.id = CONTROLVM_CHIPSET_INIT,
                .cmd.init_chipset = {
                        .bus_count = 23,
                        .switch_count = 0,
                },
        };
        u32 local_crash_msg_offset;
        u16 local_crash_msg_count;

        /* send init chipset msg */
        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 = -ENOMEM;
        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)) {
                err = -ENODEV;
                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");