[mirror_ubuntu-zesty-kernel.git] / drivers / hv / vmbus_drv.c

/*
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 *   K. Y. Srinivasan <kys@microsoft.com>
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/sysctl.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/completion.h>
#include <linux/hyperv.h>
#include <linux/kernel_stat.h>
#include <linux/clockchips.h>
#include <linux/cpu.h>
#include <asm/hyperv.h>
#include <asm/hypervisor.h>
#include <asm/mshyperv.h>
#include <linux/notifier.h>
#include <linux/ptrace.h>
#include <linux/screen_info.h>
#include <linux/kdebug.h>
#include "hyperv_vmbus.h"

static struct acpi_device  *hv_acpi_dev;

static struct tasklet_struct msg_dpc;
static struct completion probe_event;
static int irq;


static void hyperv_report_panic(struct pt_regs *regs)
{
        static bool panic_reported;

        /*
         * We prefer to report panic on 'die' chain as we have proper
         * registers to report, but if we miss it (e.g. on BUG()) we need
         * to report it on 'panic'.
         */
        if (panic_reported)
                return;
        panic_reported = true;

        wrmsrl(HV_X64_MSR_CRASH_P0, regs->ip);
        wrmsrl(HV_X64_MSR_CRASH_P1, regs->ax);
        wrmsrl(HV_X64_MSR_CRASH_P2, regs->bx);
        wrmsrl(HV_X64_MSR_CRASH_P3, regs->cx);
        wrmsrl(HV_X64_MSR_CRASH_P4, regs->dx);

        /*
         * Let Hyper-V know there is crash data available
         */
        wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
}

static int hyperv_panic_event(struct notifier_block *nb, unsigned long val,
                              void *args)
{
        struct pt_regs *regs;

        regs = current_pt_regs();

        hyperv_report_panic(regs);
        return NOTIFY_DONE;
}

static int hyperv_die_event(struct notifier_block *nb, unsigned long val,
                            void *args)
{
        struct die_args *die = (struct die_args *)args;
        struct pt_regs *regs = die->regs;

        hyperv_report_panic(regs);
        return NOTIFY_DONE;
}

static struct notifier_block hyperv_die_block = {
        .notifier_call = hyperv_die_event,
};
static struct notifier_block hyperv_panic_block = {
        .notifier_call = hyperv_panic_event,
};

struct resource *hyperv_mmio;

static int vmbus_exists(void)
{
        if (hv_acpi_dev == NULL)
                return -ENODEV;

        return 0;
}

#define VMBUS_ALIAS_LEN ((sizeof((struct hv_vmbus_device_id *)0)->guid) * 2)
static void print_alias_name(struct hv_device *hv_dev, char *alias_name)
{
        int i;
        for (i = 0; i < VMBUS_ALIAS_LEN; i += 2)
                sprintf(&alias_name[i], "%02x", hv_dev->dev_type.b[i/2]);
}

static u8 channel_monitor_group(struct vmbus_channel *channel)
{
        return (u8)channel->offermsg.monitorid / 32;
}

static u8 channel_monitor_offset(struct vmbus_channel *channel)
{
        return (u8)channel->offermsg.monitorid % 32;
}

static u32 channel_pending(struct vmbus_channel *channel,
                           struct hv_monitor_page *monitor_page)
{
        u8 monitor_group = channel_monitor_group(channel);
        return monitor_page->trigger_group[monitor_group].pending;
}

static u32 channel_latency(struct vmbus_channel *channel,
                           struct hv_monitor_page *monitor_page)
{
        u8 monitor_group = channel_monitor_group(channel);
        u8 monitor_offset = channel_monitor_offset(channel);
        return monitor_page->latency[monitor_group][monitor_offset];
}

static u32 channel_conn_id(struct vmbus_channel *channel,
                           struct hv_monitor_page *monitor_page)
{
        u8 monitor_group = channel_monitor_group(channel);
        u8 monitor_offset = channel_monitor_offset(channel);
        return monitor_page->parameter[monitor_group][monitor_offset].connectionid.u.id;
}

static ssize_t id_show(struct device *dev, struct device_attribute *dev_attr,
                       char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n", hv_dev->channel->offermsg.child_relid);
}
static DEVICE_ATTR_RO(id);

static ssize_t state_show(struct device *dev, struct device_attribute *dev_attr,
                          char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n", hv_dev->channel->state);
}
static DEVICE_ATTR_RO(state);

static ssize_t monitor_id_show(struct device *dev,
                               struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n", hv_dev->channel->offermsg.monitorid);
}
static DEVICE_ATTR_RO(monitor_id);

static ssize_t class_id_show(struct device *dev,
                               struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "{%pUl}\n",
                       hv_dev->channel->offermsg.offer.if_type.b);
}
static DEVICE_ATTR_RO(class_id);

static ssize_t device_id_show(struct device *dev,
                              struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "{%pUl}\n",
                       hv_dev->channel->offermsg.offer.if_instance.b);
}
static DEVICE_ATTR_RO(device_id);

static ssize_t modalias_show(struct device *dev,
                             struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        char alias_name[VMBUS_ALIAS_LEN + 1];

        print_alias_name(hv_dev, alias_name);
        return sprintf(buf, "vmbus:%s\n", alias_name);
}
static DEVICE_ATTR_RO(modalias);

static ssize_t server_monitor_pending_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_pending(hv_dev->channel,
                                       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(server_monitor_pending);

static ssize_t client_monitor_pending_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_pending(hv_dev->channel,
                                       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(client_monitor_pending);

static ssize_t server_monitor_latency_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_latency(hv_dev->channel,
                                       vmbus_connection.monitor_pages[0]));
}
static DEVICE_ATTR_RO(server_monitor_latency);

static ssize_t client_monitor_latency_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_latency(hv_dev->channel,
                                       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(client_monitor_latency);

static ssize_t server_monitor_conn_id_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_conn_id(hv_dev->channel,
                                       vmbus_connection.monitor_pages[0]));
}
static DEVICE_ATTR_RO(server_monitor_conn_id);

static ssize_t client_monitor_conn_id_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_conn_id(hv_dev->channel,
                                       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(client_monitor_conn_id);

static ssize_t out_intr_mask_show(struct device *dev,
                                  struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info outbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
        return sprintf(buf, "%d\n", outbound.current_interrupt_mask);
}
static DEVICE_ATTR_RO(out_intr_mask);

static ssize_t out_read_index_show(struct device *dev,
                                   struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info outbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
        return sprintf(buf, "%d\n", outbound.current_read_index);
}
static DEVICE_ATTR_RO(out_read_index);

static ssize_t out_write_index_show(struct device *dev,
                                    struct device_attribute *dev_attr,
                                    char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info outbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
        return sprintf(buf, "%d\n", outbound.current_write_index);
}
static DEVICE_ATTR_RO(out_write_index);

static ssize_t out_read_bytes_avail_show(struct device *dev,
                                         struct device_attribute *dev_attr,
                                         char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info outbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
        return sprintf(buf, "%d\n", outbound.bytes_avail_toread);
}
static DEVICE_ATTR_RO(out_read_bytes_avail);

static ssize_t out_write_bytes_avail_show(struct device *dev,
                                          struct device_attribute *dev_attr,
                                          char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info outbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
        return sprintf(buf, "%d\n", outbound.bytes_avail_towrite);
}
static DEVICE_ATTR_RO(out_write_bytes_avail);

static ssize_t in_intr_mask_show(struct device *dev,
                                 struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info inbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
        return sprintf(buf, "%d\n", inbound.current_interrupt_mask);
}
static DEVICE_ATTR_RO(in_intr_mask);

static ssize_t in_read_index_show(struct device *dev,
                                  struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info inbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
        return sprintf(buf, "%d\n", inbound.current_read_index);
}
static DEVICE_ATTR_RO(in_read_index);

static ssize_t in_write_index_show(struct device *dev,
                                   struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info inbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
        return sprintf(buf, "%d\n", inbound.current_write_index);
}
static DEVICE_ATTR_RO(in_write_index);

static ssize_t in_read_bytes_avail_show(struct device *dev,
                                        struct device_attribute *dev_attr,
                                        char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info inbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
        return sprintf(buf, "%d\n", inbound.bytes_avail_toread);
}
static DEVICE_ATTR_RO(in_read_bytes_avail);

static ssize_t in_write_bytes_avail_show(struct device *dev,
                                         struct device_attribute *dev_attr,
                                         char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info inbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
        return sprintf(buf, "%d\n", inbound.bytes_avail_towrite);
}
static DEVICE_ATTR_RO(in_write_bytes_avail);

static ssize_t channel_vp_mapping_show(struct device *dev,
                                       struct device_attribute *dev_attr,
                                       char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct vmbus_channel *channel = hv_dev->channel, *cur_sc;
        unsigned long flags;
        int buf_size = PAGE_SIZE, n_written, tot_written;
        struct list_head *cur;

        if (!channel)
                return -ENODEV;

        tot_written = snprintf(buf, buf_size, "%u:%u\n",
                channel->offermsg.child_relid, channel->target_cpu);

        spin_lock_irqsave(&channel->lock, flags);

        list_for_each(cur, &channel->sc_list) {
                if (tot_written >= buf_size - 1)
                        break;

                cur_sc = list_entry(cur, struct vmbus_channel, sc_list);
                n_written = scnprintf(buf + tot_written,
                                     buf_size - tot_written,
                                     "%u:%u\n",
                                     cur_sc->offermsg.child_relid,
                                     cur_sc->target_cpu);
                tot_written += n_written;
        }

        spin_unlock_irqrestore(&channel->lock, flags);

        return tot_written;
}
static DEVICE_ATTR_RO(channel_vp_mapping);

/* Set up per device attributes in /sys/bus/vmbus/devices/<bus device> */
static struct attribute *vmbus_attrs[] = {
        &dev_attr_id.attr,
        &dev_attr_state.attr,
        &dev_attr_monitor_id.attr,
        &dev_attr_class_id.attr,
        &dev_attr_device_id.attr,
        &dev_attr_modalias.attr,
        &dev_attr_server_monitor_pending.attr,
        &dev_attr_client_monitor_pending.attr,
        &dev_attr_server_monitor_latency.attr,
        &dev_attr_client_monitor_latency.attr,
        &dev_attr_server_monitor_conn_id.attr,
        &dev_attr_client_monitor_conn_id.attr,
        &dev_attr_out_intr_mask.attr,
        &dev_attr_out_read_index.attr,
        &dev_attr_out_write_index.attr,
        &dev_attr_out_read_bytes_avail.attr,
        &dev_attr_out_write_bytes_avail.attr,
        &dev_attr_in_intr_mask.attr,
        &dev_attr_in_read_index.attr,
        &dev_attr_in_write_index.attr,
        &dev_attr_in_read_bytes_avail.attr,
        &dev_attr_in_write_bytes_avail.attr,
        &dev_attr_channel_vp_mapping.attr,
        NULL,
};
ATTRIBUTE_GROUPS(vmbus);

/*
 * vmbus_uevent - add uevent for our device
 *
 * This routine is invoked when a device is added or removed on the vmbus to
 * generate a uevent to udev in the userspace. The udev will then look at its
 * rule and the uevent generated here to load the appropriate driver
 *
 * The alias string will be of the form vmbus:guid where guid is the string
 * representation of the device guid (each byte of the guid will be
 * represented with two hex characters.
 */
static int vmbus_uevent(struct device *device, struct kobj_uevent_env *env)
{
        struct hv_device *dev = device_to_hv_device(device);
        int ret;
        char alias_name[VMBUS_ALIAS_LEN + 1];

        print_alias_name(dev, alias_name);
        ret = add_uevent_var(env, "MODALIAS=vmbus:%s", alias_name);
        return ret;
}

static const uuid_le null_guid;

static inline bool is_null_guid(const __u8 *guid)
{
        if (memcmp(guid, &null_guid, sizeof(uuid_le)))
                return false;
        return true;
}

/*
 * Return a matching hv_vmbus_device_id pointer.
 * If there is no match, return NULL.
 */
static const struct hv_vmbus_device_id *hv_vmbus_get_id(
                                        const struct hv_vmbus_device_id *id,
                                        const __u8 *guid)
{
        for (; !is_null_guid(id->guid); id++)
                if (!memcmp(&id->guid, guid, sizeof(uuid_le)))
                        return id;

        return NULL;
}



/*
 * vmbus_match - Attempt to match the specified device to the specified driver
 */
static int vmbus_match(struct device *device, struct device_driver *driver)
{
        struct hv_driver *drv = drv_to_hv_drv(driver);
        struct hv_device *hv_dev = device_to_hv_device(device);

        if (hv_vmbus_get_id(drv->id_table, hv_dev->dev_type.b))
                return 1;

        return 0;
}

/*
 * vmbus_probe - Add the new vmbus's child device
 */
static int vmbus_probe(struct device *child_device)
{
        int ret = 0;
        struct hv_driver *drv =
                        drv_to_hv_drv(child_device->driver);
        struct hv_device *dev = device_to_hv_device(child_device);
        const struct hv_vmbus_device_id *dev_id;

        dev_id = hv_vmbus_get_id(drv->id_table, dev->dev_type.b);
        if (drv->probe) {
                ret = drv->probe(dev, dev_id);
                if (ret != 0)
                        pr_err("probe failed for device %s (%d)\n",
                               dev_name(child_device), ret);

        } else {
                pr_err("probe not set for driver %s\n",
                       dev_name(child_device));
                ret = -ENODEV;
        }
        return ret;
}

/*
 * vmbus_remove - Remove a vmbus device
 */
static int vmbus_remove(struct device *child_device)
{
        struct hv_driver *drv;
        struct hv_device *dev = device_to_hv_device(child_device);
        u32 relid = dev->channel->offermsg.child_relid;

        if (child_device->driver) {
                drv = drv_to_hv_drv(child_device->driver);
                if (drv->remove)
                        drv->remove(dev);
                else {
                        hv_process_channel_removal(dev->channel, relid);
                        pr_err("remove not set for driver %s\n",
                                dev_name(child_device));
                }
        } else {
                /*
                 * We don't have a driver for this device; deal with the
                 * rescind message by removing the channel.
                 */
                hv_process_channel_removal(dev->channel, relid);
        }

        return 0;
}


/*
 * vmbus_shutdown - Shutdown a vmbus device
 */
static void vmbus_shutdown(struct device *child_device)
{
        struct hv_driver *drv;
        struct hv_device *dev = device_to_hv_device(child_device);


        /* The device may not be attached yet */
        if (!child_device->driver)
                return;

        drv = drv_to_hv_drv(child_device->driver);

        if (drv->shutdown)
                drv->shutdown(dev);

        return;
}


/*
 * vmbus_device_release - Final callback release of the vmbus child device
 */
static void vmbus_device_release(struct device *device)
{
        struct hv_device *hv_dev = device_to_hv_device(device);

        kfree(hv_dev);

}

/* The one and only one */
static struct bus_type  hv_bus = {
        .name =         "vmbus",
        .match =                vmbus_match,
        .shutdown =             vmbus_shutdown,
        .remove =               vmbus_remove,
        .probe =                vmbus_probe,
        .uevent =               vmbus_uevent,
        .dev_groups =           vmbus_groups,
};

struct onmessage_work_context {
        struct work_struct work;
        struct hv_message msg;
};

static void vmbus_onmessage_work(struct work_struct *work)
{
        struct onmessage_work_context *ctx;

        /* Do not process messages if we're in DISCONNECTED state */
        if (vmbus_connection.conn_state == DISCONNECTED)
                return;

        ctx = container_of(work, struct onmessage_work_context,
                           work);
        vmbus_onmessage(&ctx->msg);
        kfree(ctx);
}

static void hv_process_timer_expiration(struct hv_message *msg, int cpu)
{
        struct clock_event_device *dev = hv_context.clk_evt[cpu];

        if (dev->event_handler)
                dev->event_handler(dev);

        msg->header.message_type = HVMSG_NONE;

        /*
         * Make sure the write to MessageType (ie set to
         * HVMSG_NONE) happens before we read the
         * MessagePending and EOMing. Otherwise, the EOMing
         * will not deliver any more messages since there is
         * no empty slot
         */
        mb();

        if (msg->header.message_flags.msg_pending) {
                /*
                 * This will cause message queue rescan to
                 * possibly deliver another msg from the
                 * hypervisor
                 */
                wrmsrl(HV_X64_MSR_EOM, 0);
        }
}

static void vmbus_on_msg_dpc(unsigned long data)
{
        int cpu = smp_processor_id();
        void *page_addr = hv_context.synic_message_page[cpu];
        struct hv_message *msg = (struct hv_message *)page_addr +
                                  VMBUS_MESSAGE_SINT;
        struct vmbus_channel_message_header *hdr;
        struct vmbus_channel_message_table_entry *entry;
        struct onmessage_work_context *ctx;

        while (1) {
                if (msg->header.message_type == HVMSG_NONE)
                        /* no msg */
                        break;

                hdr = (struct vmbus_channel_message_header *)msg->u.payload;

                if (hdr->msgtype >= CHANNELMSG_COUNT) {
                        WARN_ONCE(1, "unknown msgtype=%d\n", hdr->msgtype);
                        goto msg_handled;
                }

                entry = &channel_message_table[hdr->msgtype];
                if (entry->handler_type == VMHT_BLOCKING) {
                        ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
                        if (ctx == NULL)
                                continue;

                        INIT_WORK(&ctx->work, vmbus_onmessage_work);
                        memcpy(&ctx->msg, msg, sizeof(*msg));

                        queue_work(vmbus_connection.work_queue, &ctx->work);
                } else
                        entry->message_handler(hdr);

msg_handled:
                msg->header.message_type = HVMSG_NONE;

                /*
                 * Make sure the write to MessageType (ie set to
                 * HVMSG_NONE) happens before we read the
                 * MessagePending and EOMing. Otherwise, the EOMing
                 * will not deliver any more messages since there is
                 * no empty slot
                 */
                mb();

                if (msg->header.message_flags.msg_pending) {
                        /*
                         * This will cause message queue rescan to
                         * possibly deliver another msg from the
                         * hypervisor
                         */
                        wrmsrl(HV_X64_MSR_EOM, 0);
                }
        }
}

static void vmbus_isr(void)
{
        int cpu = smp_processor_id();
        void *page_addr;
        struct hv_message *msg;
        union hv_synic_event_flags *event;
        bool handled = false;

        page_addr = hv_context.synic_event_page[cpu];
        if (page_addr == NULL)
                return;

        event = (union hv_synic_event_flags *)page_addr +
                                         VMBUS_MESSAGE_SINT;
        /*
         * Check for events before checking for messages. This is the order
         * in which events and messages are checked in Windows guests on
         * Hyper-V, and the Windows team suggested we do the same.
         */

        if ((vmbus_proto_version == VERSION_WS2008) ||
                (vmbus_proto_version == VERSION_WIN7)) {

                /* Since we are a child, we only need to check bit 0 */
                if (sync_test_and_clear_bit(0,
                        (unsigned long *) &event->flags32[0])) {
                        handled = true;
                }
        } else {
                /*
                 * Our host is win8 or above. The signaling mechanism
                 * has changed and we can directly look at the event page.
                 * If bit n is set then we have an interrup on the channel
                 * whose id is n.
                 */
                handled = true;
        }

        if (handled)
                tasklet_schedule(hv_context.event_dpc[cpu]);


        page_addr = hv_context.synic_message_page[cpu];
        msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;

        /* Check if there are actual msgs to be processed */
        if (msg->header.message_type != HVMSG_NONE) {
                if (msg->header.message_type == HVMSG_TIMER_EXPIRED)
                        hv_process_timer_expiration(msg, cpu);
                else
                        tasklet_schedule(&msg_dpc);
        }
}


/*
 * vmbus_bus_init -Main vmbus driver initialization routine.
 *
 * Here, we
 *      - initialize the vmbus driver context
 *      - invoke the vmbus hv main init routine
 *      - get the irq resource
 *      - retrieve the channel offers
 */
static int vmbus_bus_init(int irq)
{
        int ret;

        /* Hypervisor initialization...setup hypercall page..etc */
        ret = hv_init();
        if (ret != 0) {
                pr_err("Unable to initialize the hypervisor - 0x%x\n", ret);
                return ret;
        }

        tasklet_init(&msg_dpc, vmbus_on_msg_dpc, 0);

        ret = bus_register(&hv_bus);
        if (ret)
                goto err_cleanup;

        hv_setup_vmbus_irq(vmbus_isr);

        ret = hv_synic_alloc();
        if (ret)
                goto err_alloc;
        /*
         * Initialize the per-cpu interrupt state and
         * connect to the host.
         */
        on_each_cpu(hv_synic_init, NULL, 1);
        ret = vmbus_connect();
        if (ret)
                goto err_connect;

        if (vmbus_proto_version > VERSION_WIN7)
                cpu_hotplug_disable();

        /*
         * Only register if the crash MSRs are available
         */
        if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
                register_die_notifier(&hyperv_die_block);
                atomic_notifier_chain_register(&panic_notifier_list,
                                               &hyperv_panic_block);
        }

        vmbus_request_offers();

        return 0;

err_connect:
        on_each_cpu(hv_synic_cleanup, NULL, 1);
err_alloc:
        hv_synic_free();
        hv_remove_vmbus_irq();

        bus_unregister(&hv_bus);

err_cleanup:
        hv_cleanup();

        return ret;
}

/**
 * __vmbus_child_driver_register() - Register a vmbus's driver
 * @hv_driver: Pointer to driver structure you want to register
 * @owner: owner module of the drv
 * @mod_name: module name string
 *
 * Registers the given driver with Linux through the 'driver_register()' call
 * and sets up the hyper-v vmbus handling for this driver.
 * It will return the state of the 'driver_register()' call.
 *
 */
int __vmbus_driver_register(struct hv_driver *hv_driver, struct module *owner, const char *mod_name)
{
        int ret;

        pr_info("registering driver %s\n", hv_driver->name);

        ret = vmbus_exists();
        if (ret < 0)
                return ret;

        hv_driver->driver.name = hv_driver->name;
        hv_driver->driver.owner = owner;
        hv_driver->driver.mod_name = mod_name;
        hv_driver->driver.bus = &hv_bus;

        ret = driver_register(&hv_driver->driver);

        return ret;
}
EXPORT_SYMBOL_GPL(__vmbus_driver_register);

/**
 * vmbus_driver_unregister() - Unregister a vmbus's driver
 * @hv_driver: Pointer to driver structure you want to
 *             un-register
 *
 * Un-register the given driver that was previous registered with a call to
 * vmbus_driver_register()
 */
void vmbus_driver_unregister(struct hv_driver *hv_driver)
{
        pr_info("unregistering driver %s\n", hv_driver->name);

        if (!vmbus_exists())
                driver_unregister(&hv_driver->driver);
}
EXPORT_SYMBOL_GPL(vmbus_driver_unregister);

/*
 * vmbus_device_create - Creates and registers a new child device
 * on the vmbus.
 */
struct hv_device *vmbus_device_create(const uuid_le *type,
                                      const uuid_le *instance,
                                      struct vmbus_channel *channel)
{
        struct hv_device *child_device_obj;

        child_device_obj = kzalloc(sizeof(struct hv_device), GFP_KERNEL);
        if (!child_device_obj) {
                pr_err("Unable to allocate device object for child device\n");
                return NULL;
        }

        child_device_obj->channel = channel;
        memcpy(&child_device_obj->dev_type, type, sizeof(uuid_le));
        memcpy(&child_device_obj->dev_instance, instance,
               sizeof(uuid_le));


        return child_device_obj;
}

/*
 * vmbus_device_register - Register the child device
 */
int vmbus_device_register(struct hv_device *child_device_obj)
{
        int ret = 0;

        dev_set_name(&child_device_obj->device, "vmbus_%d",
                     child_device_obj->channel->id);

        child_device_obj->device.bus = &hv_bus;
        child_device_obj->device.parent = &hv_acpi_dev->dev;
        child_device_obj->device.release = vmbus_device_release;

        /*
         * Register with the LDM. This will kick off the driver/device
         * binding...which will eventually call vmbus_match() and vmbus_probe()
         */
        ret = device_register(&child_device_obj->device);

        if (ret)
                pr_err("Unable to register child device\n");
        else
                pr_debug("child device %s registered\n",
                        dev_name(&child_device_obj->device));

        return ret;
}

/*
 * vmbus_device_unregister - Remove the specified child device
 * from the vmbus.
 */
void vmbus_device_unregister(struct hv_device *device_obj)
{
        pr_debug("child device %s unregistered\n",
                dev_name(&device_obj->device));

        /*
         * Kick off the process of unregistering the device.
         * This will call vmbus_remove() and eventually vmbus_device_release()
         */
        device_unregister(&device_obj->device);
}


/*
 * VMBUS is an acpi enumerated device. Get the information we
 * need from DSDT.
 */
#define VTPM_BASE_ADDRESS 0xfed40000
static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)
{
        resource_size_t start = 0;
        resource_size_t end = 0;
        struct resource *new_res;
        struct resource **old_res = &hyperv_mmio;
        struct resource **prev_res = NULL;

        switch (res->type) {
        case ACPI_RESOURCE_TYPE_IRQ:
                irq = res->data.irq.interrupts[0];
                return AE_OK;

        /*
         * "Address" descriptors are for bus windows. Ignore
         * "memory" descriptors, which are for registers on
         * devices.
         */
        case ACPI_RESOURCE_TYPE_ADDRESS32:
                start = res->data.address32.address.minimum;
                end = res->data.address32.address.maximum;
                break;

        case ACPI_RESOURCE_TYPE_ADDRESS64:
                start = res->data.address64.address.minimum;
                end = res->data.address64.address.maximum;
                break;

        default:
                /* Unused resource type */
                return AE_OK;

        }
        /*
         * Ignore ranges that are below 1MB, as they're not
         * necessary or useful here.
         */
        if (end < 0x100000)
                return AE_OK;

        new_res = kzalloc(sizeof(*new_res), GFP_ATOMIC);
        if (!new_res)
                return AE_NO_MEMORY;

        /* If this range overlaps the virtual TPM, truncate it. */
        if (end > VTPM_BASE_ADDRESS && start < VTPM_BASE_ADDRESS)
                end = VTPM_BASE_ADDRESS;

        new_res->name = "hyperv mmio";
        new_res->flags = IORESOURCE_MEM;
        new_res->start = start;
        new_res->end = end;

        do {
                if (!*old_res) {
                        *old_res = new_res;
                        break;
                }

                if ((*old_res)->end < new_res->start) {
                        new_res->sibling = *old_res;
                        if (prev_res)
                                (*prev_res)->sibling = new_res;
                        *old_res = new_res;
                        break;
                }

                prev_res = old_res;
                old_res = &(*old_res)->sibling;

        } while (1);

        return AE_OK;
}

static int vmbus_acpi_remove(struct acpi_device *device)
{
        struct resource *cur_res;
        struct resource *next_res;

        if (hyperv_mmio) {
                for (cur_res = hyperv_mmio; cur_res; cur_res = next_res) {
                        next_res = cur_res->sibling;
                        kfree(cur_res);
                }
        }

        return 0;
}

/**
 * vmbus_allocate_mmio() - Pick a memory-mapped I/O range.
 * @new:                If successful, supplied a pointer to the
 *                      allocated MMIO space.
 * @device_obj:         Identifies the caller
 * @min:                Minimum guest physical address of the
 *                      allocation
 * @max:                Maximum guest physical address
 * @size:               Size of the range to be allocated
 * @align:              Alignment of the range to be allocated
 * @fb_overlap_ok:      Whether this allocation can be allowed
 *                      to overlap the video frame buffer.
 *
 * This function walks the resources granted to VMBus by the
 * _CRS object in the ACPI namespace underneath the parent
 * "bridge" whether that's a root PCI bus in the Generation 1
 * case or a Module Device in the Generation 2 case.  It then
 * attempts to allocate from the global MMIO pool in a way that
 * matches the constraints supplied in these parameters and by
 * that _CRS.
 *
 * Return: 0 on success, -errno on failure
 */
int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
                        resource_size_t min, resource_size_t max,
                        resource_size_t size, resource_size_t align,
                        bool fb_overlap_ok)
{
        struct resource *iter;
        resource_size_t range_min, range_max, start, local_min, local_max;
        const char *dev_n = dev_name(&device_obj->device);
        u32 fb_end = screen_info.lfb_base + (screen_info.lfb_size << 1);
        int i;

        for (iter = hyperv_mmio; iter; iter = iter->sibling) {
                if ((iter->start >= max) || (iter->end <= min))
                        continue;

                range_min = iter->start;
                range_max = iter->end;

                /* If this range overlaps the frame buffer, split it into
                   two tries. */
                for (i = 0; i < 2; i++) {
                        local_min = range_min;
                        local_max = range_max;
                        if (fb_overlap_ok || (range_min >= fb_end) ||
                            (range_max <= screen_info.lfb_base)) {
                                i++;
                        } else {
                                if ((range_min <= screen_info.lfb_base) &&
                                    (range_max >= screen_info.lfb_base)) {
                                        /*
                                         * The frame buffer is in this window,
                                         * so trim this into the part that
                                         * preceeds the frame buffer.
                                         */
                                        local_max = screen_info.lfb_base - 1;
                                        range_min = fb_end;
                                } else {
                                        range_min = fb_end;
                                        continue;
                                }
                        }

                        start = (local_min + align - 1) & ~(align - 1);
                        for (; start + size - 1 <= local_max; start += align) {
                                *new = request_mem_region_exclusive(start, size,
                                                                    dev_n);
                                if (*new)
                                        return 0;
                        }
                }
        }

        return -ENXIO;
}
EXPORT_SYMBOL_GPL(vmbus_allocate_mmio);

/**
 * vmbus_cpu_number_to_vp_number() - Map CPU to VP.
 * @cpu_number: CPU number in Linux terms
 *
 * This function returns the mapping between the Linux processor
 * number and the hypervisor's virtual processor number, useful
 * in making hypercalls and such that talk about specific
 * processors.
 *
 * Return: Virtual processor number in Hyper-V terms
 */
int vmbus_cpu_number_to_vp_number(int cpu_number)
{
        return hv_context.vp_index[cpu_number];
}
EXPORT_SYMBOL_GPL(vmbus_cpu_number_to_vp_number);

static int vmbus_acpi_add(struct acpi_device *device)
{
        acpi_status result;
        int ret_val = -ENODEV;
        struct acpi_device *ancestor;

        hv_acpi_dev = device;

        result = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
                                        vmbus_walk_resources, NULL);

        if (ACPI_FAILURE(result))
                goto acpi_walk_err;
        /*
         * Some ancestor of the vmbus acpi device (Gen1 or Gen2
         * firmware) is the VMOD that has the mmio ranges. Get that.
         */
        for (ancestor = device->parent; ancestor; ancestor = ancestor->parent) {
                result = acpi_walk_resources(ancestor->handle, METHOD_NAME__CRS,
                                             vmbus_walk_resources, NULL);

                if (ACPI_FAILURE(result))
                        continue;
                if (hyperv_mmio)
                        break;
        }
        ret_val = 0;

acpi_walk_err:
        complete(&probe_event);
        if (ret_val)
                vmbus_acpi_remove(device);
        return ret_val;
}

static const struct acpi_device_id vmbus_acpi_device_ids[] = {
        {"VMBUS", 0},
        {"VMBus", 0},
        {"", 0},
};
MODULE_DEVICE_TABLE(acpi, vmbus_acpi_device_ids);

static struct acpi_driver vmbus_acpi_driver = {
        .name = "vmbus",
        .ids = vmbus_acpi_device_ids,
        .ops = {
                .add = vmbus_acpi_add,
                .remove = vmbus_acpi_remove,
        },
};

static void hv_kexec_handler(void)
{
        int cpu;

        hv_synic_clockevents_cleanup();
        vmbus_initiate_unload();
        for_each_online_cpu(cpu)
                smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
        hv_cleanup();
};

static void hv_crash_handler(struct pt_regs *regs)
{
        vmbus_initiate_unload();
        /*
         * In crash handler we can't schedule synic cleanup for all CPUs,
         * doing the cleanup for current CPU only. This should be sufficient
         * for kdump.
         */
        hv_synic_cleanup(NULL);
        hv_cleanup();
};

static int __init hv_acpi_init(void)
{
        int ret, t;

        if (x86_hyper != &x86_hyper_ms_hyperv)
                return -ENODEV;

        init_completion(&probe_event);

        /*
         * Get irq resources first.
         */
        ret = acpi_bus_register_driver(&vmbus_acpi_driver);

        if (ret)
                return ret;

        t = wait_for_completion_timeout(&probe_event, 5*HZ);
        if (t == 0) {
                ret = -ETIMEDOUT;
                goto cleanup;
        }

        if (irq <= 0) {
                ret = -ENODEV;
                goto cleanup;
        }

        ret = vmbus_bus_init(irq);
        if (ret)
                goto cleanup;

        hv_setup_kexec_handler(hv_kexec_handler);
        hv_setup_crash_handler(hv_crash_handler);

        return 0;

cleanup:
        acpi_bus_unregister_driver(&vmbus_acpi_driver);
        hv_acpi_dev = NULL;
        return ret;
}

static void __exit vmbus_exit(void)
{
        int cpu;

        hv_remove_kexec_handler();
        hv_remove_crash_handler();
        vmbus_connection.conn_state = DISCONNECTED;
        hv_synic_clockevents_cleanup();
        vmbus_disconnect();
        hv_remove_vmbus_irq();
        tasklet_kill(&msg_dpc);
        vmbus_free_channels();
        if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
                unregister_die_notifier(&hyperv_die_block);
                atomic_notifier_chain_unregister(&panic_notifier_list,
                                                 &hyperv_panic_block);
        }
        bus_unregister(&hv_bus);
        hv_cleanup();
        for_each_online_cpu(cpu) {
                tasklet_kill(hv_context.event_dpc[cpu]);
                smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
        }
        hv_synic_free();
        acpi_bus_unregister_driver(&vmbus_acpi_driver);
        if (vmbus_proto_version > VERSION_WIN7)
                cpu_hotplug_enable();
}


MODULE_LICENSE("GPL");

subsys_initcall(hv_acpi_init);
module_exit(vmbus_exit);