kernel/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  * Negotiated protocol version with the host.
  45  */
  46 __u32 vmbus_proto_version;
  47 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  48
  49 static __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_WIN8_1):
  59                 return VERSION_WIN8;
  60
  61         case (VERSION_WS2008):
  62         default:
  63                 return VERSION_INVAL;
  64         }
  65 }
  66
  67 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  68                                         __u32 version)
  69 {
  70         int ret = 0;
  71         struct vmbus_channel_initiate_contact *msg;
  72         unsigned long flags;
  73
  74         init_completion(&msginfo->waitevent);
  75
  76         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  77
  78         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  79         msg->vmbus_version_requested = version;
  80         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  81         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
  82         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
  83         if (version == VERSION_WIN8_1) {
  84                 msg->target_vcpu = hv_context.vp_index[get_cpu()];
  85                 put_cpu();
  86         }
  87
  88         /*
  89          * Add to list before we send the request since we may
  90          * receive the response before returning from this routine
  91          */
  92         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
  93         list_add_tail(&msginfo->msglistentry,
  94                       &vmbus_connection.chn_msg_list);
  95
  96         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
  97
  98         ret = vmbus_post_msg(msg,
  99                                sizeof(struct vmbus_channel_initiate_contact));
 100         if (ret != 0) {
 101                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 102                 list_del(&msginfo->msglistentry);
 103                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 104                                         flags);
 105                 return ret;
 106         }
 107
 108         /* Wait for the connection response */
 109         wait_for_completion(&msginfo->waitevent);
 110
 111         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 112         list_del(&msginfo->msglistentry);
 113         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 114
 115         /* Check if successful */
 116         if (msginfo->response.version_response.version_supported) {
 117                 vmbus_connection.conn_state = CONNECTED;
 118         } else {
 119                 return -ECONNREFUSED;
 120         }
 121
 122         return ret;
 123 }
 124
 125 /*
 126  * vmbus_connect - Sends a connect request on the partition service connection
 127  */
 128 int vmbus_connect(void)
 129 {
 130         int ret = 0;
 131         struct vmbus_channel_msginfo *msginfo = NULL;
 132         __u32 version;
 133
 134         /* Initialize the vmbus connection */
 135         vmbus_connection.conn_state = CONNECTING;
 136         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 137         if (!vmbus_connection.work_queue) {
 138                 ret = -ENOMEM;
 139                 goto cleanup;
 140         }
 141
 142         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 143         spin_lock_init(&vmbus_connection.channelmsg_lock);
 144
 145         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 146         spin_lock_init(&vmbus_connection.channel_lock);
 147
 148         /*
 149          * Setup the vmbus event connection for channel interrupt
 150          * abstraction stuff
 151          */
 152         vmbus_connection.int_page =
 153         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 154         if (vmbus_connection.int_page == NULL) {
 155                 ret = -ENOMEM;
 156                 goto cleanup;
 157         }
 158
 159         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 160         vmbus_connection.send_int_page =
 161                 (void *)((unsigned long)vmbus_connection.int_page +
 162                         (PAGE_SIZE >> 1));
 163
 164         /*
 165          * Setup the monitor notification facility. The 1st page for
 166          * parent->child and the 2nd page for child->parent
 167          */
 168         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 169         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 170         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 171             (vmbus_connection.monitor_pages[1] == NULL)) {
 172                 ret = -ENOMEM;
 173                 goto cleanup;
 174         }
 175
 176         msginfo = kzalloc(sizeof(*msginfo) +
 177                           sizeof(struct vmbus_channel_initiate_contact),
 178                           GFP_KERNEL);
 179         if (msginfo == NULL) {
 180                 ret = -ENOMEM;
 181                 goto cleanup;
 182         }
 183
 184         /*
 185          * Negotiate a compatible VMBUS version number with the
 186          * host. We start with the highest number we can support
 187          * and work our way down until we negotiate a compatible
 188          * version.
 189          */
 190
 191         version = VERSION_CURRENT;
 192
 193         do {
 194                 ret = vmbus_negotiate_version(msginfo, version);
 195                 if (ret == -ETIMEDOUT)
 196                         goto cleanup;
 197
 198                 if (vmbus_connection.conn_state == CONNECTED)
 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
 217 cleanup:
 218         pr_err("Unable to connect to host\n");
 219
 220         vmbus_connection.conn_state = DISCONNECTED;
 221         vmbus_disconnect();
 222
 223         kfree(msginfo);
 224
 225         return ret;
 226 }
 227
 228 void vmbus_disconnect(void)
 229 {
 230         if (vmbus_connection.work_queue) {
 231                 drain_workqueue(vmbus_connection.work_queue);
 232                 destroy_workqueue(vmbus_connection.work_queue);
 233         }
 234
 235         if (vmbus_connection.int_page) {
 236                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 237                 vmbus_connection.int_page = NULL;
 238         }
 239
 240         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 241         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 242         vmbus_connection.monitor_pages[0] = NULL;
 243         vmbus_connection.monitor_pages[1] = NULL;
 244 }
 245
 246 /*
 247  * Map the given relid to the corresponding channel based on the
 248  * per-cpu list of channels that have been affinitized to this CPU.
 249  * This will be used in the channel callback path as we can do this
 250  * mapping in a lock-free fashion.
 251  */
 252 static struct vmbus_channel *pcpu_relid2channel(u32 relid)
 253 {
 254         struct vmbus_channel *channel;
 255         struct vmbus_channel *found_channel  = NULL;
 256         int cpu = smp_processor_id();
 257         struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
 258
 259         list_for_each_entry(channel, pcpu_head, percpu_list) {
 260                 if (channel->offermsg.child_relid == relid) {
 261                         found_channel = channel;
 262                         break;
 263                 }
 264         }
 265
 266         return found_channel;
 267 }
 268
 269 /*
 270  * relid2channel - Get the channel object given its
 271  * child relative id (ie channel id)
 272  */
 273 struct vmbus_channel *relid2channel(u32 relid)
 274 {
 275         struct vmbus_channel *channel;
 276         struct vmbus_channel *found_channel  = NULL;
 277         unsigned long flags;
 278         struct list_head *cur, *tmp;
 279         struct vmbus_channel *cur_sc;
 280
 281         spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 282         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 283                 if (channel->offermsg.child_relid == relid) {
 284                         found_channel = channel;
 285                         break;
 286                 } else if (!list_empty(&channel->sc_list)) {
 287                         /*
 288                          * Deal with sub-channels.
 289                          */
 290                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 291                                 cur_sc = list_entry(cur, struct vmbus_channel,
 292                                                         sc_list);
 293                                 if (cur_sc->offermsg.child_relid == relid) {
 294                                         found_channel = cur_sc;
 295                                         break;
 296                                 }
 297                         }
 298                 }
 299         }
 300         spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 301
 302         return found_channel;
 303 }
 304
 305 /*
 306  * process_chn_event - Process a channel event notification
 307  */
 308 static void process_chn_event(u32 relid)
 309 {
 310         struct vmbus_channel *channel;
 311         void *arg;
 312         bool read_state;
 313         u32 bytes_to_read;
 314
 315         /*
 316          * Find the channel based on this relid and invokes the
 317          * channel callback to process the event
 318          */
 319         channel = pcpu_relid2channel(relid);
 320
 321         if (!channel)
 322                 return;
 323
 324         /*
 325          * A channel once created is persistent even when there
 326          * is no driver handling the device. An unloading driver
 327          * sets the onchannel_callback to NULL on the same CPU
 328          * as where this interrupt is handled (in an interrupt context).
 329          * Thus, checking and invoking the driver specific callback takes
 330          * care of orderly unloading of the driver.
 331          */
 332
 333         if (channel->onchannel_callback != NULL) {
 334                 arg = channel->channel_callback_context;
 335                 read_state = channel->batched_reading;
 336                 /*
 337                  * This callback reads the messages sent by the host.
 338                  * We can optimize host to guest signaling by ensuring:
 339                  * 1. While reading the channel, we disable interrupts from
 340                  *    host.
 341                  * 2. Ensure that we process all posted messages from the host
 342                  *    before returning from this callback.
 343                  * 3. Once we return, enable signaling from the host. Once this
 344                  *    state is set we check to see if additional packets are
 345                  *    available to read. In this case we repeat the process.
 346                  */
 347
 348                 do {
 349                         if (read_state)
 350                                 hv_begin_read(&channel->inbound);
 351                         channel->onchannel_callback(arg);
 352                         if (read_state)
 353                                 bytes_to_read = hv_end_read(&channel->inbound);
 354                         else
 355                                 bytes_to_read = 0;
 356                 } while (read_state && (bytes_to_read != 0));
 357         }
 358 }
 359
 360 /*
 361  * vmbus_on_event - Handler for events
 362  */
 363 void vmbus_on_event(unsigned long data)
 364 {
 365         u32 dword;
 366         u32 maxdword;
 367         int bit;
 368         u32 relid;
 369         u32 *recv_int_page = NULL;
 370         void *page_addr;
 371         int cpu = smp_processor_id();
 372         union hv_synic_event_flags *event;
 373
 374         if ((vmbus_proto_version == VERSION_WS2008) ||
 375                 (vmbus_proto_version == VERSION_WIN7)) {
 376                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 377                 recv_int_page = vmbus_connection.recv_int_page;
 378         } else {
 379                 /*
 380                  * When the host is win8 and beyond, the event page
 381                  * can be directly checked to get the id of the channel
 382                  * that has the interrupt pending.
 383                  */
 384                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 385                 page_addr = hv_context.synic_event_page[cpu];
 386                 event = (union hv_synic_event_flags *)page_addr +
 387                                                  VMBUS_MESSAGE_SINT;
 388                 recv_int_page = event->flags32;
 389         }
 390
 391
 392
 393         /* Check events */
 394         if (!recv_int_page)
 395                 return;
 396         for (dword = 0; dword < maxdword; dword++) {
 397                 if (!recv_int_page[dword])
 398                         continue;
 399                 for (bit = 0; bit < 32; bit++) {
 400                         if (sync_test_and_clear_bit(bit,
 401                                 (unsigned long *)&recv_int_page[dword])) {
 402                                 relid = (dword << 5) + bit;
 403
 404                                 if (relid == 0)
 405                                         /*
 406                                          * Special case - vmbus
 407                                          * channel protocol msg
 408                                          */
 409                                         continue;
 410
 411                                 process_chn_event(relid);
 412                         }
 413                 }
 414         }
 415 }
 416
 417 /*
 418  * vmbus_post_msg - Send a msg on the vmbus's message connection
 419  */
 420 int vmbus_post_msg(void *buffer, size_t buflen)
 421 {
 422         union hv_connection_id conn_id;
 423         int ret = 0;
 424         int retries = 0;
 425         u32 msec = 1;
 426
 427         conn_id.asu32 = 0;
 428         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 429
 430         /*
 431          * hv_post_message() can have transient failures because of
 432          * insufficient resources. Retry the operation a couple of
 433          * times before giving up.
 434          */
 435         while (retries < 20) {
 436                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 437
 438                 switch (ret) {
 439                 case HV_STATUS_INVALID_CONNECTION_ID:
 440                         /*
 441                          * We could get this if we send messages too
 442                          * frequently.
 443                          */
 444                         ret = -EAGAIN;
 445                         break;
 446                 case HV_STATUS_INSUFFICIENT_MEMORY:
 447                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 448                         ret = -ENOMEM;
 449                         break;
 450                 case HV_STATUS_SUCCESS:
 451                         return ret;
 452                 default:
 453                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 454                         return -EINVAL;
 455                 }
 456
 457                 retries++;
 458                 msleep(msec);
 459                 if (msec < 2048)
 460                         msec *= 2;
 461         }
 462         return ret;
 463 }
 464
 465 /*
 466  * vmbus_set_event - Send an event notification to the parent
 467  */
 468 int vmbus_set_event(struct vmbus_channel *channel)
 469 {
 470         u32 child_relid = channel->offermsg.child_relid;
 471
 472         if (!channel->is_dedicated_interrupt) {
 473                 /* Each u32 represents 32 channels */
 474                 sync_set_bit(child_relid & 31,
 475                         (unsigned long *)vmbus_connection.send_int_page +
 476                         (child_relid >> 5));
 477         }
 478
 479         return hv_signal_event(channel->sig_event);
 480 }