drivers/hv/connection.c

   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
  38 struct vmbus_connection vmbus_connection = {
  39         .conn_state             = DISCONNECTED,
  40         .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),
  41 };
  42
  43 /*
  44  * VMBUS version is 32 bit entity broken up into
  45  * two 16 bit quantities: major_number. minor_number.
  46  *
  47  * 0 . 13 (Windows Server 2008)
  48  * 1 . 1  (Windows 7)
  49  * 2 . 4  (Windows 8)
  50  */
  51
  52 #define VERSION_WS2008  ((0 << 16) | (13))
  53 #define VERSION_WIN7    ((1 << 16) | (1))
  54 #define VERSION_WIN8    ((2 << 16) | (4))
  55
  56 #define VERSION_INVAL -1
  57
  58 /*
  59  * Negotiated protocol version with the host.
  60  */
  61 __u32 vmbus_proto_version;
  62 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  63
  64 static __u32 vmbus_get_next_version(__u32 current_version)
  65 {
  66         switch (current_version) {
  67         case (VERSION_WIN7):
  68                 return VERSION_WS2008;
  69
  70         case (VERSION_WIN8):
  71                 return VERSION_WIN7;
  72
  73         case (VERSION_WS2008):
  74         default:
  75                 return VERSION_INVAL;
  76         }
  77 }
  78
  79 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  80                                         __u32 version)
  81 {
  82         int ret = 0;
  83         struct vmbus_channel_initiate_contact *msg;
  84         unsigned long flags;
  85         int t;
  86
  87         init_completion(&msginfo->waitevent);
  88
  89         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  90
  91         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  92         msg->vmbus_version_requested = version;
  93         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  94         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages);
  95         msg->monitor_page2 = virt_to_phys(
  96                         (void *)((unsigned long)vmbus_connection.monitor_pages +
  97                                  PAGE_SIZE));
  98
  99         /*
 100          * Add to list before we send the request since we may
 101          * receive the response before returning from this routine
 102          */
 103         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 104         list_add_tail(&msginfo->msglistentry,
 105                       &vmbus_connection.chn_msg_list);
 106
 107         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 108
 109         ret = vmbus_post_msg(msg,
 110                                sizeof(struct vmbus_channel_initiate_contact));
 111         if (ret != 0) {
 112                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 113                 list_del(&msginfo->msglistentry);
 114                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 115                                         flags);
 116                 return ret;
 117         }
 118
 119         /* Wait for the connection response */
 120         t =  wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
 121         if (t == 0) {
 122                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock,
 123                                 flags);
 124                 list_del(&msginfo->msglistentry);
 125                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 126                                         flags);
 127                 return -ETIMEDOUT;
 128         }
 129
 130         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 131         list_del(&msginfo->msglistentry);
 132         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 133
 134         /* Check if successful */
 135         if (msginfo->response.version_response.version_supported) {
 136                 vmbus_connection.conn_state = CONNECTED;
 137         } else {
 138                 pr_err("Unable to connect, "
 139                         "Version %d not supported by Hyper-V\n",
 140                         version);
 141                 return -ECONNREFUSED;
 142         }
 143
 144         return ret;
 145 }
 146
 147 /*
 148  * vmbus_connect - Sends a connect request on the partition service connection
 149  */
 150 int vmbus_connect(void)
 151 {
 152         int ret = 0;
 153         struct vmbus_channel_msginfo *msginfo = NULL;
 154         __u32 version;
 155
 156         /* Initialize the vmbus connection */
 157         vmbus_connection.conn_state = CONNECTING;
 158         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 159         if (!vmbus_connection.work_queue) {
 160                 ret = -ENOMEM;
 161                 goto cleanup;
 162         }
 163
 164         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 165         spin_lock_init(&vmbus_connection.channelmsg_lock);
 166
 167         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 168         spin_lock_init(&vmbus_connection.channel_lock);
 169
 170         /*
 171          * Setup the vmbus event connection for channel interrupt
 172          * abstraction stuff
 173          */
 174         vmbus_connection.int_page =
 175         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 176         if (vmbus_connection.int_page == NULL) {
 177                 ret = -ENOMEM;
 178                 goto cleanup;
 179         }
 180
 181         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 182         vmbus_connection.send_int_page =
 183                 (void *)((unsigned long)vmbus_connection.int_page +
 184                         (PAGE_SIZE >> 1));
 185
 186         /*
 187          * Setup the monitor notification facility. The 1st page for
 188          * parent->child and the 2nd page for child->parent
 189          */
 190         vmbus_connection.monitor_pages =
 191         (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 1);
 192         if (vmbus_connection.monitor_pages == NULL) {
 193                 ret = -ENOMEM;
 194                 goto cleanup;
 195         }
 196
 197         msginfo = kzalloc(sizeof(*msginfo) +
 198                           sizeof(struct vmbus_channel_initiate_contact),
 199                           GFP_KERNEL);
 200         if (msginfo == NULL) {
 201                 ret = -ENOMEM;
 202                 goto cleanup;
 203         }
 204
 205         /*
 206          * Negotiate a compatible VMBUS version number with the
 207          * host. We start with the highest number we can support
 208          * and work our way down until we negotiate a compatible
 209          * version.
 210          */
 211
 212         version = VERSION_WS2008;
 213
 214         do {
 215                 ret = vmbus_negotiate_version(msginfo, version);
 216                 if (ret == 0)
 217                         break;
 218
 219                 version = vmbus_get_next_version(version);
 220         } while (version != VERSION_INVAL);
 221
 222         if (version == VERSION_INVAL)
 223                 goto cleanup;
 224
 225         vmbus_proto_version = version;
 226         pr_info("Negotiated host information %d\n", version);
 227         kfree(msginfo);
 228         return 0;
 229
 230 cleanup:
 231         vmbus_connection.conn_state = DISCONNECTED;
 232
 233         if (vmbus_connection.work_queue)
 234                 destroy_workqueue(vmbus_connection.work_queue);
 235
 236         if (vmbus_connection.int_page) {
 237                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 238                 vmbus_connection.int_page = NULL;
 239         }
 240
 241         if (vmbus_connection.monitor_pages) {
 242                 free_pages((unsigned long)vmbus_connection.monitor_pages, 1);
 243                 vmbus_connection.monitor_pages = NULL;
 244         }
 245
 246         kfree(msginfo);
 247
 248         return ret;
 249 }
 250
 251
 252 /*
 253  * relid2channel - Get the channel object given its
 254  * child relative id (ie channel id)
 255  */
 256 struct vmbus_channel *relid2channel(u32 relid)
 257 {
 258         struct vmbus_channel *channel;
 259         struct vmbus_channel *found_channel  = NULL;
 260         unsigned long flags;
 261
 262         spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 263         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 264                 if (channel->offermsg.child_relid == relid) {
 265                         found_channel = channel;
 266                         break;
 267                 }
 268         }
 269         spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 270
 271         return found_channel;
 272 }
 273
 274 /*
 275  * process_chn_event - Process a channel event notification
 276  */
 277 static void process_chn_event(u32 relid)
 278 {
 279         struct vmbus_channel *channel;
 280         unsigned long flags;
 281         void *arg;
 282         bool read_state;
 283         u32 bytes_to_read;
 284
 285         /*
 286          * Find the channel based on this relid and invokes the
 287          * channel callback to process the event
 288          */
 289         channel = relid2channel(relid);
 290
 291         if (!channel) {
 292                 pr_err("channel not found for relid - %u\n", relid);
 293                 return;
 294         }
 295
 296         /*
 297          * A channel once created is persistent even when there
 298          * is no driver handling the device. An unloading driver
 299          * sets the onchannel_callback to NULL under the
 300          * protection of the channel inbound_lock. Thus, checking
 301          * and invoking the driver specific callback takes care of
 302          * orderly unloading of the driver.
 303          */
 304
 305         spin_lock_irqsave(&channel->inbound_lock, flags);
 306         if (channel->onchannel_callback != NULL) {
 307                 arg = channel->channel_callback_context;
 308                 read_state = channel->batched_reading;
 309                 /*
 310                  * This callback reads the messages sent by the host.
 311                  * We can optimize host to guest signaling by ensuring:
 312                  * 1. While reading the channel, we disable interrupts from
 313                  *    host.
 314                  * 2. Ensure that we process all posted messages from the host
 315                  *    before returning from this callback.
 316                  * 3. Once we return, enable signaling from the host. Once this
 317                  *    state is set we check to see if additional packets are
 318                  *    available to read. In this case we repeat the process.
 319                  */
 320
 321                 do {
 322                         hv_begin_read(&channel->inbound);
 323                         channel->onchannel_callback(arg);
 324                         bytes_to_read = hv_end_read(&channel->inbound);
 325                 } while (read_state && (bytes_to_read != 0));
 326         } else {
 327                 pr_err("no channel callback for relid - %u\n", relid);
 328         }
 329
 330         spin_unlock_irqrestore(&channel->inbound_lock, flags);
 331 }
 332
 333 /*
 334  * vmbus_on_event - Handler for events
 335  */
 336 void vmbus_on_event(unsigned long data)
 337 {
 338         u32 dword;
 339         u32 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 340         int bit;
 341         u32 relid;
 342         u32 *recv_int_page = vmbus_connection.recv_int_page;
 343
 344         /* Check events */
 345         if (!recv_int_page)
 346                 return;
 347         for (dword = 0; dword < maxdword; dword++) {
 348                 if (!recv_int_page[dword])
 349                         continue;
 350                 for (bit = 0; bit < 32; bit++) {
 351                         if (sync_test_and_clear_bit(bit,
 352                                 (unsigned long *)&recv_int_page[dword])) {
 353                                 relid = (dword << 5) + bit;
 354
 355                                 if (relid == 0)
 356                                         /*
 357                                          * Special case - vmbus
 358                                          * channel protocol msg
 359                                          */
 360                                         continue;
 361
 362                                 process_chn_event(relid);
 363                         }
 364                 }
 365         }
 366 }
 367
 368 /*
 369  * vmbus_post_msg - Send a msg on the vmbus's message connection
 370  */
 371 int vmbus_post_msg(void *buffer, size_t buflen)
 372 {
 373         union hv_connection_id conn_id;
 374         int ret = 0;
 375         int retries = 0;
 376
 377         conn_id.asu32 = 0;
 378         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 379
 380         /*
 381          * hv_post_message() can have transient failures because of
 382          * insufficient resources. Retry the operation a couple of
 383          * times before giving up.
 384          */
 385         while (retries < 3) {
 386                 ret =  hv_post_message(conn_id, 1, buffer, buflen);
 387                 if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
 388                         return ret;
 389                 retries++;
 390                 msleep(100);
 391         }
 392         return ret;
 393 }
 394
 395 /*
 396  * vmbus_set_event - Send an event notification to the parent
 397  */
 398 int vmbus_set_event(u32 child_relid)
 399 {
 400         /* Each u32 represents 32 channels */
 401         sync_set_bit(child_relid & 31,
 402                 (unsigned long *)vmbus_connection.send_int_page +
 403                 (child_relid >> 5));
 404
 405         return hv_signal_event(hv_context.signal_event_param);
 406 }