connection.c

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/*
 *
 * 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 <[email protected]>
 *   Hank Janssen  <[email protected]>
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/hyperv.h>
#include <asm/hyperv.h>
#include "hyperv_vmbus.h"


struct vmbus_connection vmbus_connection = {
    .conn_state     = DISCONNECTED,
    .next_gpadl_handle  = ATOMIC_INIT(0xE1E10),
};

/*
 * vmbus_connect - Sends a connect request on the partition service connection
 */
int vmbus_connect(void)
{
    int ret = 0;
    int t;
    struct vmbus_channel_msginfo *msginfo = NULL;
    struct vmbus_channel_initiate_contact *msg;
    unsigned long flags;

    /* Initialize the vmbus connection */
    vmbus_connection.conn_state = CONNECTING;
    vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
    if (!vmbus_connection.work_queue) {
        ret = -ENOMEM;
        goto cleanup;
    }

    INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
    spin_lock_init(&vmbus_connection.channelmsg_lock);

    INIT_LIST_HEAD(&vmbus_connection.chn_list);
    spin_lock_init(&vmbus_connection.channel_lock);

    /*
     * Setup the vmbus event connection for channel interrupt
     * abstraction stuff
     */
    vmbus_connection.int_page =
    (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
    if (vmbus_connection.int_page == NULL) {
        ret = -ENOMEM;
        goto cleanup;
    }

    vmbus_connection.recv_int_page = vmbus_connection.int_page;
    vmbus_connection.send_int_page =
        (void *)((unsigned long)vmbus_connection.int_page +
            (PAGE_SIZE >> 1));

    /*
     * Setup the monitor notification facility. The 1st page for
     * parent->child and the 2nd page for child->parent
     */
    vmbus_connection.monitor_pages =
    (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 1);
    if (vmbus_connection.monitor_pages == NULL) {
        ret = -ENOMEM;
        goto cleanup;
    }

    msginfo = kzalloc(sizeof(*msginfo) +
              sizeof(struct vmbus_channel_initiate_contact),
              GFP_KERNEL);
    if (msginfo == NULL) {
        ret = -ENOMEM;
        goto cleanup;
    }

    init_completion(&msginfo->waitevent);

    msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;

    msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
    msg->vmbus_version_requested = VMBUS_REVISION_NUMBER;
    msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
    msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages);
    msg->monitor_page2 = virt_to_phys(
            (void *)((unsigned long)vmbus_connection.monitor_pages +
                 PAGE_SIZE));

    /*
     * Add to list before we send the request since we may
     * receive the response before returning from this routine
     */
    spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
    list_add_tail(&msginfo->msglistentry,
              &vmbus_connection.chn_msg_list);

    spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);

    ret = vmbus_post_msg(msg,
                   sizeof(struct vmbus_channel_initiate_contact));
    if (ret != 0) {
        spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
        list_del(&msginfo->msglistentry);
        spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
                    flags);
        goto cleanup;
    }

    /* Wait for the connection response */
    t =  wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
    if (t == 0) {
        spin_lock_irqsave(&vmbus_connection.channelmsg_lock,
                flags);
        list_del(&msginfo->msglistentry);
        spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
                    flags);
        ret = -ETIMEDOUT;
        goto cleanup;
    }

    spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
    list_del(&msginfo->msglistentry);
    spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);

    /* Check if successful */
    if (msginfo->response.version_response.version_supported) {
        vmbus_connection.conn_state = CONNECTED;
    } else {
        pr_err("Unable to connect, "
            "Version %d not supported by Hyper-V\n",
            VMBUS_REVISION_NUMBER);
        ret = -ECONNREFUSED;
        goto cleanup;
    }

    kfree(msginfo);
    return 0;

cleanup:
    vmbus_connection.conn_state = DISCONNECTED;

    if (vmbus_connection.work_queue)
        destroy_workqueue(vmbus_connection.work_queue);

    if (vmbus_connection.int_page) {
        free_pages((unsigned long)vmbus_connection.int_page, 0);
        vmbus_connection.int_page = NULL;
    }

    if (vmbus_connection.monitor_pages) {
        free_pages((unsigned long)vmbus_connection.monitor_pages, 1);
        vmbus_connection.monitor_pages = NULL;
    }

    kfree(msginfo);

    return ret;
}


/*
 * relid2channel - Get the channel object given its
 * child relative id (ie channel id)
 */
struct vmbus_channel *relid2channel(u32 relid)
{
    struct vmbus_channel *channel;
    struct vmbus_channel *found_channel  = NULL;
    unsigned long flags;

    spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
    list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
        if (channel->offermsg.child_relid == relid) {
            found_channel = channel;
            break;
        }
    }
    spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);

    return found_channel;
}

/*
 * process_chn_event - Process a channel event notification
 */
static void process_chn_event(u32 relid)
{
    struct vmbus_channel *channel;
    unsigned long flags;

    /*
     * Find the channel based on this relid and invokes the
     * channel callback to process the event
     */
    channel = relid2channel(relid);

    if (!channel) {
        pr_err("channel not found for relid - %u\n", relid);
        return;
    }

    /*
     * A channel once created is persistent even when there
     * is no driver handling the device. An unloading driver
     * sets the onchannel_callback to NULL under the
     * protection of the channel inbound_lock. Thus, checking
     * and invoking the driver specific callback takes care of
     * orderly unloading of the driver.
     */

    spin_lock_irqsave(&channel->inbound_lock, flags);
    if (channel->onchannel_callback != NULL)
        channel->onchannel_callback(channel->channel_callback_context);
    else
        pr_err("no channel callback for relid - %u\n", relid);

    spin_unlock_irqrestore(&channel->inbound_lock, flags);
}

/*
 * vmbus_on_event - Handler for events
 */
void vmbus_on_event(unsigned long data)
{
    u32 dword;
    u32 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
    int bit;
    u32 relid;
    u32 *recv_int_page = vmbus_connection.recv_int_page;

    /* Check events */
    if (!recv_int_page)
        return;
    for (dword = 0; dword < maxdword; dword++) {
        if (!recv_int_page[dword])
            continue;
        for (bit = 0; bit < 32; bit++) {
            if (sync_test_and_clear_bit(bit,
                (unsigned long *)&recv_int_page[dword])) {
                relid = (dword << 5) + bit;

                if (relid == 0)
                    /*
                     * Special case - vmbus
                     * channel protocol msg
                     */
                    continue;

                process_chn_event(relid);
            }
        }
    }
}

/*
 * vmbus_post_msg - Send a msg on the vmbus's message connection
 */
int vmbus_post_msg(void *buffer, size_t buflen)
{
    union hv_connection_id conn_id;
    int ret = 0;
    int retries = 0;

    conn_id.asu32 = 0;
    conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;

    /*
     * hv_post_message() can have transient failures because of
     * insufficient resources. Retry the operation a couple of
     * times before giving up.
     */
    while (retries < 3) {
        ret =  hv_post_message(conn_id, 1, buffer, buflen);
        if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
            return ret;
        retries++;
        msleep(100);
    }
    return ret;
}

/*
 * vmbus_set_event - Send an event notification to the parent
 */
int vmbus_set_event(u32 child_relid)
{
    /* Each u32 represents 32 channels */
    sync_set_bit(child_relid & 31,
        (unsigned long *)vmbus_connection.send_int_page +
        (child_relid >> 5));

    return hv_signal_event();
}