linux/drivers/hv/connection.c
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   1/*
   2 *
   3 * Copyright (c) 2009, Microsoft Corporation.
   4 *
   5 * This program is free software; you can redistribute it and/or modify it
   6 * under the terms and conditions of the GNU General Public License,
   7 * version 2, as published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope it will be useful, but WITHOUT
  10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12 * more details.
  13 *
  14 * You should have received a copy of the GNU General Public License along with
  15 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  16 * Place - Suite 330, Boston, MA 02111-1307 USA.
  17 *
  18 * Authors:
  19 *   Haiyang Zhang <haiyangz@microsoft.com>
  20 *   Hank Janssen  <hjanssen@microsoft.com>
  21 *
  22 */
  23#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  24
  25#include <linux/kernel.h>
  26#include <linux/sched.h>
  27#include <linux/wait.h>
  28#include <linux/delay.h>
  29#include <linux/mm.h>
  30#include <linux/slab.h>
  31#include <linux/vmalloc.h>
  32#include <linux/hyperv.h>
  33#include <linux/export.h>
  34#include <asm/hyperv.h>
  35#include "hyperv_vmbus.h"
  36
  37
  38struct vmbus_connection vmbus_connection = {
  39        .conn_state             = DISCONNECTED,
  40        .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),
  41};
  42
  43/*
  44 * Negotiated protocol version with the host.
  45 */
  46__u32 vmbus_proto_version;
  47EXPORT_SYMBOL_GPL(vmbus_proto_version);
  48
  49static __u32 vmbus_get_next_version(__u32 current_version)
  50{
  51        switch (current_version) {
  52        case (VERSION_WIN7):
  53                return VERSION_WS2008;
  54
  55        case (VERSION_WIN8):
  56                return VERSION_WIN7;
  57
  58        case (VERSION_WS2008):
  59        default:
  60                return VERSION_INVAL;
  61        }
  62}
  63
  64static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  65                                        __u32 version)
  66{
  67        int ret = 0;
  68        struct vmbus_channel_initiate_contact *msg;
  69        unsigned long flags;
  70        int t;
  71
  72        init_completion(&msginfo->waitevent);
  73
  74        msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  75
  76        msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  77        msg->vmbus_version_requested = version;
  78        msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  79        msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages);
  80        msg->monitor_page2 = virt_to_phys(
  81                        (void *)((unsigned long)vmbus_connection.monitor_pages +
  82                                 PAGE_SIZE));
  83
  84        /*
  85         * Add to list before we send the request since we may
  86         * receive the response before returning from this routine
  87         */
  88        spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
  89        list_add_tail(&msginfo->msglistentry,
  90                      &vmbus_connection.chn_msg_list);
  91
  92        spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
  93
  94        ret = vmbus_post_msg(msg,
  95                               sizeof(struct vmbus_channel_initiate_contact));
  96        if (ret != 0) {
  97                spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
  98                list_del(&msginfo->msglistentry);
  99                spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 100                                        flags);
 101                return ret;
 102        }
 103
 104        /* Wait for the connection response */
 105        t =  wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
 106        if (t == 0) {
 107                spin_lock_irqsave(&vmbus_connection.channelmsg_lock,
 108                                flags);
 109                list_del(&msginfo->msglistentry);
 110                spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 111                                        flags);
 112                return -ETIMEDOUT;
 113        }
 114
 115        spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 116        list_del(&msginfo->msglistentry);
 117        spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 118
 119        /* Check if successful */
 120        if (msginfo->response.version_response.version_supported) {
 121                vmbus_connection.conn_state = CONNECTED;
 122        } else {
 123                return -ECONNREFUSED;
 124        }
 125
 126        return ret;
 127}
 128
 129/*
 130 * vmbus_connect - Sends a connect request on the partition service connection
 131 */
 132int vmbus_connect(void)
 133{
 134        int ret = 0;
 135        struct vmbus_channel_msginfo *msginfo = NULL;
 136        __u32 version;
 137
 138        /* Initialize the vmbus connection */
 139        vmbus_connection.conn_state = CONNECTING;
 140        vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 141        if (!vmbus_connection.work_queue) {
 142                ret = -ENOMEM;
 143                goto cleanup;
 144        }
 145
 146        INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 147        spin_lock_init(&vmbus_connection.channelmsg_lock);
 148
 149        INIT_LIST_HEAD(&vmbus_connection.chn_list);
 150        spin_lock_init(&vmbus_connection.channel_lock);
 151
 152        /*
 153         * Setup the vmbus event connection for channel interrupt
 154         * abstraction stuff
 155         */
 156        vmbus_connection.int_page =
 157        (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 158        if (vmbus_connection.int_page == NULL) {
 159                ret = -ENOMEM;
 160                goto cleanup;
 161        }
 162
 163        vmbus_connection.recv_int_page = vmbus_connection.int_page;
 164        vmbus_connection.send_int_page =
 165                (void *)((unsigned long)vmbus_connection.int_page +
 166                        (PAGE_SIZE >> 1));
 167
 168        /*
 169         * Setup the monitor notification facility. The 1st page for
 170         * parent->child and the 2nd page for child->parent
 171         */
 172        vmbus_connection.monitor_pages =
 173        (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 1);
 174        if (vmbus_connection.monitor_pages == NULL) {
 175                ret = -ENOMEM;
 176                goto cleanup;
 177        }
 178
 179        msginfo = kzalloc(sizeof(*msginfo) +
 180                          sizeof(struct vmbus_channel_initiate_contact),
 181                          GFP_KERNEL);
 182        if (msginfo == NULL) {
 183                ret = -ENOMEM;
 184                goto cleanup;
 185        }
 186
 187        /*
 188         * Negotiate a compatible VMBUS version number with the
 189         * host. We start with the highest number we can support
 190         * and work our way down until we negotiate a compatible
 191         * version.
 192         */
 193
 194        version = VERSION_CURRENT;
 195
 196        do {
 197                ret = vmbus_negotiate_version(msginfo, version);
 198                if (ret == 0)
 199                        break;
 200
 201                version = vmbus_get_next_version(version);
 202        } while (version != VERSION_INVAL);
 203
 204        if (version == VERSION_INVAL)
 205                goto cleanup;
 206
 207        vmbus_proto_version = version;
 208        pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
 209                    host_info_eax, host_info_ebx >> 16,
 210                    host_info_ebx & 0xFFFF, host_info_ecx,
 211                    host_info_edx >> 24, host_info_edx & 0xFFFFFF,
 212                    version >> 16, version & 0xFFFF);
 213
 214        kfree(msginfo);
 215        return 0;
 216
 217cleanup:
 218        pr_err("Unable to connect to host\n");
 219        vmbus_connection.conn_state = DISCONNECTED;
 220
 221        if (vmbus_connection.work_queue)
 222                destroy_workqueue(vmbus_connection.work_queue);
 223
 224        if (vmbus_connection.int_page) {
 225                free_pages((unsigned long)vmbus_connection.int_page, 0);
 226                vmbus_connection.int_page = NULL;
 227        }
 228
 229        if (vmbus_connection.monitor_pages) {
 230                free_pages((unsigned long)vmbus_connection.monitor_pages, 1);
 231                vmbus_connection.monitor_pages = NULL;
 232        }
 233
 234        kfree(msginfo);
 235
 236        return ret;
 237}
 238
 239
 240/*
 241 * relid2channel - Get the channel object given its
 242 * child relative id (ie channel id)
 243 */
 244struct vmbus_channel *relid2channel(u32 relid)
 245{
 246        struct vmbus_channel *channel;
 247        struct vmbus_channel *found_channel  = NULL;
 248        unsigned long flags;
 249
 250        spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 251        list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 252                if (channel->offermsg.child_relid == relid) {
 253                        found_channel = channel;
 254                        break;
 255                }
 256        }
 257        spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 258
 259        return found_channel;
 260}
 261
 262/*
 263 * process_chn_event - Process a channel event notification
 264 */
 265static void process_chn_event(u32 relid)
 266{
 267        struct vmbus_channel *channel;
 268        unsigned long flags;
 269        void *arg;
 270        bool read_state;
 271        u32 bytes_to_read;
 272
 273        /*
 274         * Find the channel based on this relid and invokes the
 275         * channel callback to process the event
 276         */
 277        channel = relid2channel(relid);
 278
 279        if (!channel) {
 280                pr_err("channel not found for relid - %u\n", relid);
 281                return;
 282        }
 283
 284        /*
 285         * A channel once created is persistent even when there
 286         * is no driver handling the device. An unloading driver
 287         * sets the onchannel_callback to NULL under the
 288         * protection of the channel inbound_lock. Thus, checking
 289         * and invoking the driver specific callback takes care of
 290         * orderly unloading of the driver.
 291         */
 292
 293        spin_lock_irqsave(&channel->inbound_lock, flags);
 294        if (channel->onchannel_callback != NULL) {
 295                arg = channel->channel_callback_context;
 296                read_state = channel->batched_reading;
 297                /*
 298                 * This callback reads the messages sent by the host.
 299                 * We can optimize host to guest signaling by ensuring:
 300                 * 1. While reading the channel, we disable interrupts from
 301                 *    host.
 302                 * 2. Ensure that we process all posted messages from the host
 303                 *    before returning from this callback.
 304                 * 3. Once we return, enable signaling from the host. Once this
 305                 *    state is set we check to see if additional packets are
 306                 *    available to read. In this case we repeat the process.
 307                 */
 308
 309                do {
 310                        hv_begin_read(&channel->inbound);
 311                        channel->onchannel_callback(arg);
 312                        bytes_to_read = hv_end_read(&channel->inbound);
 313                } while (read_state && (bytes_to_read != 0));
 314        } else {
 315                pr_err("no channel callback for relid - %u\n", relid);
 316        }
 317
 318        spin_unlock_irqrestore(&channel->inbound_lock, flags);
 319}
 320
 321/*
 322 * vmbus_on_event - Handler for events
 323 */
 324void vmbus_on_event(unsigned long data)
 325{
 326        u32 dword;
 327        u32 maxdword;
 328        int bit;
 329        u32 relid;
 330        u32 *recv_int_page = NULL;
 331        void *page_addr;
 332        int cpu = smp_processor_id();
 333        union hv_synic_event_flags *event;
 334
 335        if ((vmbus_proto_version == VERSION_WS2008) ||
 336                (vmbus_proto_version == VERSION_WIN7)) {
 337                maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 338                recv_int_page = vmbus_connection.recv_int_page;
 339        } else {
 340                /*
 341                 * When the host is win8 and beyond, the event page
 342                 * can be directly checked to get the id of the channel
 343                 * that has the interrupt pending.
 344                 */
 345                maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 346                page_addr = hv_context.synic_event_page[cpu];
 347                event = (union hv_synic_event_flags *)page_addr +
 348                                                 VMBUS_MESSAGE_SINT;
 349                recv_int_page = event->flags32;
 350        }
 351
 352
 353
 354        /* Check events */
 355        if (!recv_int_page)
 356                return;
 357        for (dword = 0; dword < maxdword; dword++) {
 358                if (!recv_int_page[dword])
 359                        continue;
 360                for (bit = 0; bit < 32; bit++) {
 361                        if (sync_test_and_clear_bit(bit,
 362                                (unsigned long *)&recv_int_page[dword])) {
 363                                relid = (dword << 5) + bit;
 364
 365                                if (relid == 0)
 366                                        /*
 367                                         * Special case - vmbus
 368                                         * channel protocol msg
 369                                         */
 370                                        continue;
 371
 372                                process_chn_event(relid);
 373                        }
 374                }
 375        }
 376}
 377
 378/*
 379 * vmbus_post_msg - Send a msg on the vmbus's message connection
 380 */
 381int vmbus_post_msg(void *buffer, size_t buflen)
 382{
 383        union hv_connection_id conn_id;
 384        int ret = 0;
 385        int retries = 0;
 386
 387        conn_id.asu32 = 0;
 388        conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 389
 390        /*
 391         * hv_post_message() can have transient failures because of
 392         * insufficient resources. Retry the operation a couple of
 393         * times before giving up.
 394         */
 395        while (retries < 3) {
 396                ret =  hv_post_message(conn_id, 1, buffer, buflen);
 397                if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
 398                        return ret;
 399                retries++;
 400                msleep(100);
 401        }
 402        return ret;
 403}
 404
 405/*
 406 * vmbus_set_event - Send an event notification to the parent
 407 */
 408int vmbus_set_event(struct vmbus_channel *channel)
 409{
 410        u32 child_relid = channel->offermsg.child_relid;
 411
 412        if (!channel->is_dedicated_interrupt) {
 413                /* Each u32 represents 32 channels */
 414                sync_set_bit(child_relid & 31,
 415                        (unsigned long *)vmbus_connection.send_int_page +
 416                        (child_relid >> 5));
 417        }
 418
 419        return hv_signal_event(channel->sig_event);
 420}
 421
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