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 == -ETIMEDOUT)
 199                        goto cleanup;
 200
 201                if (vmbus_connection.conn_state == CONNECTED)
 202                        break;
 203
 204                version = vmbus_get_next_version(version);
 205        } while (version != VERSION_INVAL);
 206
 207        if (version == VERSION_INVAL)
 208                goto cleanup;
 209
 210        vmbus_proto_version = version;
 211        pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
 212                    host_info_eax, host_info_ebx >> 16,
 213                    host_info_ebx & 0xFFFF, host_info_ecx,
 214                    host_info_edx >> 24, host_info_edx & 0xFFFFFF,
 215                    version >> 16, version & 0xFFFF);
 216
 217        kfree(msginfo);
 218        return 0;
 219
 220cleanup:
 221        pr_err("Unable to connect to host\n");
 222        vmbus_connection.conn_state = DISCONNECTED;
 223
 224        if (vmbus_connection.work_queue)
 225                destroy_workqueue(vmbus_connection.work_queue);
 226
 227        if (vmbus_connection.int_page) {
 228                free_pages((unsigned long)vmbus_connection.int_page, 0);
 229                vmbus_connection.int_page = NULL;
 230        }
 231
 232        if (vmbus_connection.monitor_pages) {
 233                free_pages((unsigned long)vmbus_connection.monitor_pages, 1);
 234                vmbus_connection.monitor_pages = NULL;
 235        }
 236
 237        kfree(msginfo);
 238
 239        return ret;
 240}
 241
 242
 243/*
 244 * relid2channel - Get the channel object given its
 245 * child relative id (ie channel id)
 246 */
 247struct vmbus_channel *relid2channel(u32 relid)
 248{
 249        struct vmbus_channel *channel;
 250        struct vmbus_channel *found_channel  = NULL;
 251        unsigned long flags;
 252        struct list_head *cur, *tmp;
 253        struct vmbus_channel *cur_sc;
 254
 255        spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 256        list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 257                if (channel->offermsg.child_relid == relid) {
 258                        found_channel = channel;
 259                        break;
 260                } else if (!list_empty(&channel->sc_list)) {
 261                        /*
 262                         * Deal with sub-channels.
 263                         */
 264                        list_for_each_safe(cur, tmp, &channel->sc_list) {
 265                                cur_sc = list_entry(cur, struct vmbus_channel,
 266                                                        sc_list);
 267                                if (cur_sc->offermsg.child_relid == relid) {
 268                                        found_channel = cur_sc;
 269                                        break;
 270                                }
 271                        }
 272                }
 273        }
 274        spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 275
 276        return found_channel;
 277}
 278
 279/*
 280 * process_chn_event - Process a channel event notification
 281 */
 282static void process_chn_event(u32 relid)
 283{
 284        struct vmbus_channel *channel;
 285        unsigned long flags;
 286        void *arg;
 287        bool read_state;
 288        u32 bytes_to_read;
 289
 290        /*
 291         * Find the channel based on this relid and invokes the
 292         * channel callback to process the event
 293         */
 294        channel = relid2channel(relid);
 295
 296        if (!channel) {
 297                pr_err("channel not found for relid - %u\n", relid);
 298                return;
 299        }
 300
 301        /*
 302         * A channel once created is persistent even when there
 303         * is no driver handling the device. An unloading driver
 304         * sets the onchannel_callback to NULL under the
 305         * protection of the channel inbound_lock. Thus, checking
 306         * and invoking the driver specific callback takes care of
 307         * orderly unloading of the driver.
 308         */
 309
 310        spin_lock_irqsave(&channel->inbound_lock, flags);
 311        if (channel->onchannel_callback != NULL) {
 312                arg = channel->channel_callback_context;
 313                read_state = channel->batched_reading;
 314                /*
 315                 * This callback reads the messages sent by the host.
 316                 * We can optimize host to guest signaling by ensuring:
 317                 * 1. While reading the channel, we disable interrupts from
 318                 *    host.
 319                 * 2. Ensure that we process all posted messages from the host
 320                 *    before returning from this callback.
 321                 * 3. Once we return, enable signaling from the host. Once this
 322                 *    state is set we check to see if additional packets are
 323                 *    available to read. In this case we repeat the process.
 324                 */
 325
 326                do {
 327                        hv_begin_read(&channel->inbound);
 328                        channel->onchannel_callback(arg);
 329                        bytes_to_read = hv_end_read(&channel->inbound);
 330                } while (read_state && (bytes_to_read != 0));
 331        } else {
 332                pr_err("no channel callback for relid - %u\n", relid);
 333        }
 334
 335        spin_unlock_irqrestore(&channel->inbound_lock, flags);
 336}
 337
 338/*
 339 * vmbus_on_event - Handler for events
 340 */
 341void vmbus_on_event(unsigned long data)
 342{
 343        u32 dword;
 344        u32 maxdword;
 345        int bit;
 346        u32 relid;
 347        u32 *recv_int_page = NULL;
 348        void *page_addr;
 349        int cpu = smp_processor_id();
 350        union hv_synic_event_flags *event;
 351
 352        if ((vmbus_proto_version == VERSION_WS2008) ||
 353                (vmbus_proto_version == VERSION_WIN7)) {
 354                maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 355                recv_int_page = vmbus_connection.recv_int_page;
 356        } else {
 357                /*
 358                 * When the host is win8 and beyond, the event page
 359                 * can be directly checked to get the id of the channel
 360                 * that has the interrupt pending.
 361                 */
 362                maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 363                page_addr = hv_context.synic_event_page[cpu];
 364                event = (union hv_synic_event_flags *)page_addr +
 365                                                 VMBUS_MESSAGE_SINT;
 366                recv_int_page = event->flags32;
 367        }
 368
 369
 370
 371        /* Check events */
 372        if (!recv_int_page)
 373                return;
 374        for (dword = 0; dword < maxdword; dword++) {
 375                if (!recv_int_page[dword])
 376                        continue;
 377                for (bit = 0; bit < 32; bit++) {
 378                        if (sync_test_and_clear_bit(bit,
 379                                (unsigned long *)&recv_int_page[dword])) {
 380                                relid = (dword << 5) + bit;
 381
 382                                if (relid == 0)
 383                                        /*
 384                                         * Special case - vmbus
 385                                         * channel protocol msg
 386                                         */
 387                                        continue;
 388
 389                                process_chn_event(relid);
 390                        }
 391                }
 392        }
 393}
 394
 395/*
 396 * vmbus_post_msg - Send a msg on the vmbus's message connection
 397 */
 398int vmbus_post_msg(void *buffer, size_t buflen)
 399{
 400        union hv_connection_id conn_id;
 401        int ret = 0;
 402        int retries = 0;
 403
 404        conn_id.asu32 = 0;
 405        conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 406
 407        /*
 408         * hv_post_message() can have transient failures because of
 409         * insufficient resources. Retry the operation a couple of
 410         * times before giving up.
 411         */
 412        while (retries < 3) {
 413                ret =  hv_post_message(conn_id, 1, buffer, buflen);
 414                if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
 415                        return ret;
 416                retries++;
 417                msleep(100);
 418        }
 419        return ret;
 420}
 421
 422/*
 423 * vmbus_set_event - Send an event notification to the parent
 424 */
 425int vmbus_set_event(struct vmbus_channel *channel)
 426{
 427        u32 child_relid = channel->offermsg.child_relid;
 428
 429        if (!channel->is_dedicated_interrupt) {
 430                /* Each u32 represents 32 channels */
 431                sync_set_bit(child_relid & 31,
 432                        (unsigned long *)vmbus_connection.send_int_page +
 433                        (child_relid >> 5));
 434        }
 435
 436        return hv_signal_event(channel->sig_event);
 437}
 438
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