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 EXPORT_SYMBOL_GPL(vmbus_connection);
  43
  44 /*
  45  * Negotiated protocol version with the host.
  46  */
  47 __u32 vmbus_proto_version;
  48 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  49
  50 static __u32 vmbus_get_next_version(__u32 current_version)
  51 {
  52         switch (current_version) {
  53         case (VERSION_WIN7):
  54                 return VERSION_WS2008;
  55
  56         case (VERSION_WIN8):
  57                 return VERSION_WIN7;
  58
  59         case (VERSION_WIN8_1):
  60                 return VERSION_WIN8;
  61
  62         case (VERSION_WIN10):
  63                 return VERSION_WIN8_1;
  64
  65         case (VERSION_WS2008):
  66         default:
  67                 return VERSION_INVAL;
  68         }
  69 }
  70
  71 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  72                                         __u32 version)
  73 {
  74         int ret = 0;
  75         struct vmbus_channel_initiate_contact *msg;
  76         unsigned long flags;
  77
  78         init_completion(&msginfo->waitevent);
  79
  80         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  81
  82         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  83         msg->vmbus_version_requested = version;
  84         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  85         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
  86         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
  87         /*
  88          * We want all channel messages to be delivered on CPU 0.
  89          * This has been the behavior pre-win8. This is not
  90          * perf issue and having all channel messages delivered on CPU 0
  91          * would be ok.
  92          * For post win8 hosts, we support receiving channel messagges on
  93          * all the CPUs. This is needed for kexec to work correctly where
  94          * the CPU attempting to connect may not be CPU 0.
  95          */
  96         if (version >= VERSION_WIN8_1) {
  97                 msg->target_vcpu = hv_context.vp_index[get_cpu()];
  98                 put_cpu();
  99         } else {
 100                 msg->target_vcpu = 0;
 101         }
 102
 103         /*
 104          * Add to list before we send the request since we may
 105          * receive the response before returning from this routine
 106          */
 107         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 108         list_add_tail(&msginfo->msglistentry,
 109                       &vmbus_connection.chn_msg_list);
 110
 111         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 112
 113         ret = vmbus_post_msg(msg,
 114                              sizeof(struct vmbus_channel_initiate_contact),
 115                              true);
 116         if (ret != 0) {
 117                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 118                 list_del(&msginfo->msglistentry);
 119                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 120                                         flags);
 121                 return ret;
 122         }
 123
 124         /* Wait for the connection response */
 125         wait_for_completion(&msginfo->waitevent);
 126
 127         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 128         list_del(&msginfo->msglistentry);
 129         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 130
 131         /* Check if successful */
 132         if (msginfo->response.version_response.version_supported) {
 133                 vmbus_connection.conn_state = CONNECTED;
 134         } else {
 135                 return -ECONNREFUSED;
 136         }
 137
 138         return ret;
 139 }
 140
 141 /*
 142  * vmbus_connect - Sends a connect request on the partition service connection
 143  */
 144 int vmbus_connect(void)
 145 {
 146         int ret = 0;
 147         struct vmbus_channel_msginfo *msginfo = NULL;
 148         __u32 version;
 149
 150         /* Initialize the vmbus connection */
 151         vmbus_connection.conn_state = CONNECTING;
 152         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 153         if (!vmbus_connection.work_queue) {
 154                 ret = -ENOMEM;
 155                 goto cleanup;
 156         }
 157
 158         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 159         spin_lock_init(&vmbus_connection.channelmsg_lock);
 160
 161         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 162         mutex_init(&vmbus_connection.channel_mutex);
 163
 164         /*
 165          * Setup the vmbus event connection for channel interrupt
 166          * abstraction stuff
 167          */
 168         vmbus_connection.int_page =
 169         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 170         if (vmbus_connection.int_page == NULL) {
 171                 ret = -ENOMEM;
 172                 goto cleanup;
 173         }
 174
 175         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 176         vmbus_connection.send_int_page =
 177                 (void *)((unsigned long)vmbus_connection.int_page +
 178                         (PAGE_SIZE >> 1));
 179
 180         /*
 181          * Setup the monitor notification facility. The 1st page for
 182          * parent->child and the 2nd page for child->parent
 183          */
 184         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 185         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 186         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 187             (vmbus_connection.monitor_pages[1] == NULL)) {
 188                 ret = -ENOMEM;
 189                 goto cleanup;
 190         }
 191
 192         msginfo = kzalloc(sizeof(*msginfo) +
 193                           sizeof(struct vmbus_channel_initiate_contact),
 194                           GFP_KERNEL);
 195         if (msginfo == NULL) {
 196                 ret = -ENOMEM;
 197                 goto cleanup;
 198         }
 199
 200         /*
 201          * Negotiate a compatible VMBUS version number with the
 202          * host. We start with the highest number we can support
 203          * and work our way down until we negotiate a compatible
 204          * version.
 205          */
 206
 207         version = VERSION_CURRENT;
 208
 209         do {
 210                 ret = vmbus_negotiate_version(msginfo, version);
 211                 if (ret == -ETIMEDOUT)
 212                         goto cleanup;
 213
 214                 if (vmbus_connection.conn_state == CONNECTED)
 215                         break;
 216
 217                 version = vmbus_get_next_version(version);
 218         } while (version != VERSION_INVAL);
 219
 220         if (version == VERSION_INVAL)
 221                 goto cleanup;
 222
 223         vmbus_proto_version = version;
 224         pr_info("Vmbus version:%d.%d\n",
 225                 version >> 16, version & 0xFFFF);
 226
 227         kfree(msginfo);
 228         return 0;
 229
 230 cleanup:
 231         pr_err("Unable to connect to host\n");
 232
 233         vmbus_connection.conn_state = DISCONNECTED;
 234         vmbus_disconnect();
 235
 236         kfree(msginfo);
 237
 238         return ret;
 239 }
 240
 241 void vmbus_disconnect(void)
 242 {
 243         /*
 244          * First send the unload request to the host.
 245          */
 246         vmbus_initiate_unload(false);
 247
 248         if (vmbus_connection.work_queue) {
 249                 drain_workqueue(vmbus_connection.work_queue);
 250                 destroy_workqueue(vmbus_connection.work_queue);
 251         }
 252
 253         if (vmbus_connection.int_page) {
 254                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 255                 vmbus_connection.int_page = NULL;
 256         }
 257
 258         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 259         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 260         vmbus_connection.monitor_pages[0] = NULL;
 261         vmbus_connection.monitor_pages[1] = NULL;
 262 }
 263
 264 /*
 265  * Map the given relid to the corresponding channel based on the
 266  * per-cpu list of channels that have been affinitized to this CPU.
 267  * This will be used in the channel callback path as we can do this
 268  * mapping in a lock-free fashion.
 269  */
 270 static struct vmbus_channel *pcpu_relid2channel(u32 relid)
 271 {
 272         struct vmbus_channel *channel;
 273         struct vmbus_channel *found_channel  = NULL;
 274         int cpu = smp_processor_id();
 275         struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
 276
 277         list_for_each_entry(channel, pcpu_head, percpu_list) {
 278                 if (channel->offermsg.child_relid == relid) {
 279                         found_channel = channel;
 280                         break;
 281                 }
 282         }
 283
 284         return found_channel;
 285 }
 286
 287 /*
 288  * relid2channel - Get the channel object given its
 289  * child relative id (ie channel id)
 290  */
 291 struct vmbus_channel *relid2channel(u32 relid)
 292 {
 293         struct vmbus_channel *channel;
 294         struct vmbus_channel *found_channel  = NULL;
 295         struct list_head *cur, *tmp;
 296         struct vmbus_channel *cur_sc;
 297
 298         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 299
 300         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 301                 if (channel->offermsg.child_relid == relid) {
 302                         found_channel = channel;
 303                         break;
 304                 } else if (!list_empty(&channel->sc_list)) {
 305                         /*
 306                          * Deal with sub-channels.
 307                          */
 308                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 309                                 cur_sc = list_entry(cur, struct vmbus_channel,
 310                                                         sc_list);
 311                                 if (cur_sc->offermsg.child_relid == relid) {
 312                                         found_channel = cur_sc;
 313                                         break;
 314                                 }
 315                         }
 316                 }
 317         }
 318
 319         return found_channel;
 320 }
 321
 322 /*
 323  * process_chn_event - Process a channel event notification
 324  */
 325 static void process_chn_event(u32 relid)
 326 {
 327         struct vmbus_channel *channel;
 328         void *arg;
 329         bool read_state;
 330         u32 bytes_to_read;
 331
 332         /*
 333          * Find the channel based on this relid and invokes the
 334          * channel callback to process the event
 335          */
 336         channel = pcpu_relid2channel(relid);
 337
 338         if (!channel)
 339                 return;
 340
 341         /*
 342          * A channel once created is persistent even when there
 343          * is no driver handling the device. An unloading driver
 344          * sets the onchannel_callback to NULL on the same CPU
 345          * as where this interrupt is handled (in an interrupt context).
 346          * Thus, checking and invoking the driver specific callback takes
 347          * care of orderly unloading of the driver.
 348          */
 349
 350         if (channel->onchannel_callback != NULL) {
 351                 arg = channel->channel_callback_context;
 352                 read_state = channel->batched_reading;
 353                 /*
 354                  * This callback reads the messages sent by the host.
 355                  * We can optimize host to guest signaling by ensuring:
 356                  * 1. While reading the channel, we disable interrupts from
 357                  *    host.
 358                  * 2. Ensure that we process all posted messages from the host
 359                  *    before returning from this callback.
 360                  * 3. Once we return, enable signaling from the host. Once this
 361                  *    state is set we check to see if additional packets are
 362                  *    available to read. In this case we repeat the process.
 363                  */
 364
 365                 do {
 366                         if (read_state)
 367                                 hv_begin_read(&channel->inbound);
 368                         channel->onchannel_callback(arg);
 369                         if (read_state)
 370                                 bytes_to_read = hv_end_read(&channel->inbound);
 371                         else
 372                                 bytes_to_read = 0;
 373                 } while (read_state && (bytes_to_read != 0));
 374         }
 375 }
 376
 377 /*
 378  * vmbus_on_event - Handler for events
 379  */
 380 void vmbus_on_event(unsigned long data)
 381 {
 382         u32 dword;
 383         u32 maxdword;
 384         int bit;
 385         u32 relid;
 386         u32 *recv_int_page = NULL;
 387         void *page_addr;
 388         int cpu = smp_processor_id();
 389         union hv_synic_event_flags *event;
 390
 391         if (vmbus_proto_version < VERSION_WIN8) {
 392                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 393                 recv_int_page = vmbus_connection.recv_int_page;
 394         } else {
 395                 /*
 396                  * When the host is win8 and beyond, the event page
 397                  * can be directly checked to get the id of the channel
 398                  * that has the interrupt pending.
 399                  */
 400                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 401                 page_addr = hv_context.synic_event_page[cpu];
 402                 event = (union hv_synic_event_flags *)page_addr +
 403                                                  VMBUS_MESSAGE_SINT;
 404                 recv_int_page = event->flags32;
 405         }
 406
 407
 408
 409         /* Check events */
 410         if (!recv_int_page)
 411                 return;
 412         for (dword = 0; dword < maxdword; dword++) {
 413                 if (!recv_int_page[dword])
 414                         continue;
 415                 for (bit = 0; bit < 32; bit++) {
 416                         if (sync_test_and_clear_bit(bit,
 417                                 (unsigned long *)&recv_int_page[dword])) {
 418                                 relid = (dword << 5) + bit;
 419
 420                                 if (relid == 0)
 421                                         /*
 422                                          * Special case - vmbus
 423                                          * channel protocol msg
 424                                          */
 425                                         continue;
 426
 427                                 process_chn_event(relid);
 428                         }
 429                 }
 430         }
 431 }
 432
 433 /*
 434  * vmbus_post_msg - Send a msg on the vmbus's message connection
 435  */
 436 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 437 {
 438         union hv_connection_id conn_id;
 439         int ret = 0;
 440         int retries = 0;
 441         u32 usec = 1;
 442
 443         conn_id.asu32 = 0;
 444         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 445
 446         /*
 447          * hv_post_message() can have transient failures because of
 448          * insufficient resources. Retry the operation a couple of
 449          * times before giving up.
 450          */
 451         while (retries < 100) {
 452                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 453
 454                 switch (ret) {
 455                 case HV_STATUS_INVALID_CONNECTION_ID:
 456                         /*
 457                          * We could get this if we send messages too
 458                          * frequently.
 459                          */
 460                         ret = -EAGAIN;
 461                         break;
 462                 case HV_STATUS_INSUFFICIENT_MEMORY:
 463                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 464                         ret = -ENOMEM;
 465                         break;
 466                 case HV_STATUS_SUCCESS:
 467                         return ret;
 468                 default:
 469                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 470                         return -EINVAL;
 471                 }
 472
 473                 retries++;
 474                 if (can_sleep && usec > 1000)
 475                         msleep(usec / 1000);
 476                 else if (usec < MAX_UDELAY_MS * 1000)
 477                         udelay(usec);
 478                 else
 479                         mdelay(usec / 1000);
 480
 481                 if (usec < 256000)
 482                         usec *= 2;
 483         }
 484         return ret;
 485 }
 486
 487 /*
 488  * vmbus_set_event - Send an event notification to the parent
 489  */
 490 void vmbus_set_event(struct vmbus_channel *channel)
 491 {
 492         u32 child_relid = channel->offermsg.child_relid;
 493
 494         if (!channel->is_dedicated_interrupt) {
 495                 /* Each u32 represents 32 channels */
 496                 sync_set_bit(child_relid & 31,
 497                         (unsigned long *)vmbus_connection.send_int_page +
 498                         (child_relid >> 5));
 499         }
 500
 501         hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
 502 }
 503 EXPORT_SYMBOL_GPL(vmbus_set_event);