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_WIN10):
  62                 return VERSION_WIN8_1;
  63
  64         case (VERSION_WS2008):
  65         default:
  66                 return VERSION_INVAL;
  67         }
  68 }
  69
  70 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  71                                         __u32 version)
  72 {
  73         int ret = 0;
  74         struct vmbus_channel_initiate_contact *msg;
  75         unsigned long flags;
  76
  77         init_completion(&msginfo->waitevent);
  78
  79         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  80
  81         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  82         msg->vmbus_version_requested = version;
  83         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  84         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
  85         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
  86         /*
  87          * We want all channel messages to be delivered on CPU 0.
  88          * This has been the behavior pre-win8. This is not
  89          * perf issue and having all channel messages delivered on CPU 0
  90          * would be ok.
  91          */
  92         msg->target_vcpu = 0;
  93
  94         /*
  95          * Add to list before we send the request since we may
  96          * receive the response before returning from this routine
  97          */
  98         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
  99         list_add_tail(&msginfo->msglistentry,
 100                       &vmbus_connection.chn_msg_list);
 101
 102         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 103
 104         ret = vmbus_post_msg(msg,
 105                                sizeof(struct vmbus_channel_initiate_contact));
 106         if (ret != 0) {
 107                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 108                 list_del(&msginfo->msglistentry);
 109                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 110                                         flags);
 111                 return ret;
 112         }
 113
 114         /* Wait for the connection response */
 115         wait_for_completion(&msginfo->waitevent);
 116
 117         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 118         list_del(&msginfo->msglistentry);
 119         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 120
 121         /* Check if successful */
 122         if (msginfo->response.version_response.version_supported) {
 123                 vmbus_connection.conn_state = CONNECTED;
 124         } else {
 125                 return -ECONNREFUSED;
 126         }
 127
 128         return ret;
 129 }
 130
 131 /*
 132  * vmbus_connect - Sends a connect request on the partition service connection
 133  */
 134 int vmbus_connect(void)
 135 {
 136         int ret = 0;
 137         struct vmbus_channel_msginfo *msginfo = NULL;
 138         __u32 version;
 139
 140         /* Initialize the vmbus connection */
 141         vmbus_connection.conn_state = CONNECTING;
 142         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 143         if (!vmbus_connection.work_queue) {
 144                 ret = -ENOMEM;
 145                 goto cleanup;
 146         }
 147
 148         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 149         spin_lock_init(&vmbus_connection.channelmsg_lock);
 150
 151         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 152         mutex_init(&vmbus_connection.channel_mutex);
 153
 154         /*
 155          * Setup the vmbus event connection for channel interrupt
 156          * abstraction stuff
 157          */
 158         vmbus_connection.int_page =
 159         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 160         if (vmbus_connection.int_page == NULL) {
 161                 ret = -ENOMEM;
 162                 goto cleanup;
 163         }
 164
 165         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 166         vmbus_connection.send_int_page =
 167                 (void *)((unsigned long)vmbus_connection.int_page +
 168                         (PAGE_SIZE >> 1));
 169
 170         /*
 171          * Setup the monitor notification facility. The 1st page for
 172          * parent->child and the 2nd page for child->parent
 173          */
 174         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 175         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 176         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 177             (vmbus_connection.monitor_pages[1] == NULL)) {
 178                 ret = -ENOMEM;
 179                 goto cleanup;
 180         }
 181
 182         msginfo = kzalloc(sizeof(*msginfo) +
 183                           sizeof(struct vmbus_channel_initiate_contact),
 184                           GFP_KERNEL);
 185         if (msginfo == NULL) {
 186                 ret = -ENOMEM;
 187                 goto cleanup;
 188         }
 189
 190         /*
 191          * Negotiate a compatible VMBUS version number with the
 192          * host. We start with the highest number we can support
 193          * and work our way down until we negotiate a compatible
 194          * version.
 195          */
 196
 197         version = VERSION_CURRENT;
 198
 199         do {
 200                 ret = vmbus_negotiate_version(msginfo, version);
 201                 if (ret == -ETIMEDOUT)
 202                         goto cleanup;
 203
 204                 if (vmbus_connection.conn_state == CONNECTED)
 205                         break;
 206
 207                 version = vmbus_get_next_version(version);
 208         } while (version != VERSION_INVAL);
 209
 210         if (version == VERSION_INVAL)
 211                 goto cleanup;
 212
 213         vmbus_proto_version = version;
 214         pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
 215                     host_info_eax, host_info_ebx >> 16,
 216                     host_info_ebx & 0xFFFF, host_info_ecx,
 217                     host_info_edx >> 24, host_info_edx & 0xFFFFFF,
 218                     version >> 16, version & 0xFFFF);
 219
 220         kfree(msginfo);
 221         return 0;
 222
 223 cleanup:
 224         pr_err("Unable to connect to host\n");
 225
 226         vmbus_connection.conn_state = DISCONNECTED;
 227         vmbus_disconnect();
 228
 229         kfree(msginfo);
 230
 231         return ret;
 232 }
 233
 234 void vmbus_disconnect(void)
 235 {
 236         /*
 237          * First send the unload request to the host.
 238          */
 239         vmbus_initiate_unload();
 240
 241         if (vmbus_connection.work_queue) {
 242                 drain_workqueue(vmbus_connection.work_queue);
 243                 destroy_workqueue(vmbus_connection.work_queue);
 244         }
 245
 246         if (vmbus_connection.int_page) {
 247                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 248                 vmbus_connection.int_page = NULL;
 249         }
 250
 251         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 252         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 253         vmbus_connection.monitor_pages[0] = NULL;
 254         vmbus_connection.monitor_pages[1] = NULL;
 255 }
 256
 257 /*
 258  * Map the given relid to the corresponding channel based on the
 259  * per-cpu list of channels that have been affinitized to this CPU.
 260  * This will be used in the channel callback path as we can do this
 261  * mapping in a lock-free fashion.
 262  */
 263 static struct vmbus_channel *pcpu_relid2channel(u32 relid)
 264 {
 265         struct vmbus_channel *channel;
 266         struct vmbus_channel *found_channel  = NULL;
 267         int cpu = smp_processor_id();
 268         struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
 269
 270         list_for_each_entry(channel, pcpu_head, percpu_list) {
 271                 if (channel->offermsg.child_relid == relid) {
 272                         found_channel = channel;
 273                         break;
 274                 }
 275         }
 276
 277         return found_channel;
 278 }
 279
 280 /*
 281  * relid2channel - Get the channel object given its
 282  * child relative id (ie channel id)
 283  */
 284 struct vmbus_channel *relid2channel(u32 relid)
 285 {
 286         struct vmbus_channel *channel;
 287         struct vmbus_channel *found_channel  = NULL;
 288         struct list_head *cur, *tmp;
 289         struct vmbus_channel *cur_sc;
 290
 291         mutex_lock(&vmbus_connection.channel_mutex);
 292         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 293                 if (channel->offermsg.child_relid == relid) {
 294                         found_channel = channel;
 295                         break;
 296                 } else if (!list_empty(&channel->sc_list)) {
 297                         /*
 298                          * Deal with sub-channels.
 299                          */
 300                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 301                                 cur_sc = list_entry(cur, struct vmbus_channel,
 302                                                         sc_list);
 303                                 if (cur_sc->offermsg.child_relid == relid) {
 304                                         found_channel = cur_sc;
 305                                         break;
 306                                 }
 307                         }
 308                 }
 309         }
 310         mutex_unlock(&vmbus_connection.channel_mutex);
 311
 312         return found_channel;
 313 }
 314
 315 /*
 316  * process_chn_event - Process a channel event notification
 317  */
 318 static void process_chn_event(u32 relid)
 319 {
 320         struct vmbus_channel *channel;
 321         void *arg;
 322         bool read_state;
 323         u32 bytes_to_read;
 324
 325         /*
 326          * Find the channel based on this relid and invokes the
 327          * channel callback to process the event
 328          */
 329         channel = pcpu_relid2channel(relid);
 330
 331         if (!channel)
 332                 return;
 333
 334         /*
 335          * A channel once created is persistent even when there
 336          * is no driver handling the device. An unloading driver
 337          * sets the onchannel_callback to NULL on the same CPU
 338          * as where this interrupt is handled (in an interrupt context).
 339          * Thus, checking and invoking the driver specific callback takes
 340          * care of orderly unloading of the driver.
 341          */
 342
 343         if (channel->onchannel_callback != NULL) {
 344                 arg = channel->channel_callback_context;
 345                 read_state = channel->batched_reading;
 346                 /*
 347                  * This callback reads the messages sent by the host.
 348                  * We can optimize host to guest signaling by ensuring:
 349                  * 1. While reading the channel, we disable interrupts from
 350                  *    host.
 351                  * 2. Ensure that we process all posted messages from the host
 352                  *    before returning from this callback.
 353                  * 3. Once we return, enable signaling from the host. Once this
 354                  *    state is set we check to see if additional packets are
 355                  *    available to read. In this case we repeat the process.
 356                  */
 357
 358                 do {
 359                         if (read_state)
 360                                 hv_begin_read(&channel->inbound);
 361                         channel->onchannel_callback(arg);
 362                         if (read_state)
 363                                 bytes_to_read = hv_end_read(&channel->inbound);
 364                         else
 365                                 bytes_to_read = 0;
 366                 } while (read_state && (bytes_to_read != 0));
 367         }
 368 }
 369
 370 /*
 371  * vmbus_on_event - Handler for events
 372  */
 373 void vmbus_on_event(unsigned long data)
 374 {
 375         u32 dword;
 376         u32 maxdword;
 377         int bit;
 378         u32 relid;
 379         u32 *recv_int_page = NULL;
 380         void *page_addr;
 381         int cpu = smp_processor_id();
 382         union hv_synic_event_flags *event;
 383
 384         if (vmbus_proto_version < VERSION_WIN8) {
 385                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 386                 recv_int_page = vmbus_connection.recv_int_page;
 387         } else {
 388                 /*
 389                  * When the host is win8 and beyond, the event page
 390                  * can be directly checked to get the id of the channel
 391                  * that has the interrupt pending.
 392                  */
 393                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 394                 page_addr = hv_context.synic_event_page[cpu];
 395                 event = (union hv_synic_event_flags *)page_addr +
 396                                                  VMBUS_MESSAGE_SINT;
 397                 recv_int_page = event->flags32;
 398         }
 399
 400
 401
 402         /* Check events */
 403         if (!recv_int_page)
 404                 return;
 405         for (dword = 0; dword < maxdword; dword++) {
 406                 if (!recv_int_page[dword])
 407                         continue;
 408                 for (bit = 0; bit < 32; bit++) {
 409                         if (sync_test_and_clear_bit(bit,
 410                                 (unsigned long *)&recv_int_page[dword])) {
 411                                 relid = (dword << 5) + bit;
 412
 413                                 if (relid == 0)
 414                                         /*
 415                                          * Special case - vmbus
 416                                          * channel protocol msg
 417                                          */
 418                                         continue;
 419
 420                                 process_chn_event(relid);
 421                         }
 422                 }
 423         }
 424 }
 425
 426 /*
 427  * vmbus_post_msg - Send a msg on the vmbus's message connection
 428  */
 429 int vmbus_post_msg(void *buffer, size_t buflen)
 430 {
 431         union hv_connection_id conn_id;
 432         int ret = 0;
 433         int retries = 0;
 434         u32 msec = 1;
 435
 436         conn_id.asu32 = 0;
 437         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 438
 439         /*
 440          * hv_post_message() can have transient failures because of
 441          * insufficient resources. Retry the operation a couple of
 442          * times before giving up.
 443          */
 444         while (retries < 20) {
 445                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 446
 447                 switch (ret) {
 448                 case HV_STATUS_INVALID_CONNECTION_ID:
 449                         /*
 450                          * We could get this if we send messages too
 451                          * frequently.
 452                          */
 453                         ret = -EAGAIN;
 454                         break;
 455                 case HV_STATUS_INSUFFICIENT_MEMORY:
 456                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 457                         ret = -ENOMEM;
 458                         break;
 459                 case HV_STATUS_SUCCESS:
 460                         return ret;
 461                 default:
 462                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 463                         return -EINVAL;
 464                 }
 465
 466                 retries++;
 467                 msleep(msec);
 468                 if (msec < 2048)
 469                         msec *= 2;
 470         }
 471         return ret;
 472 }
 473
 474 /*
 475  * vmbus_set_event - Send an event notification to the parent
 476  */
 477 int vmbus_set_event(struct vmbus_channel *channel)
 478 {
 479         u32 child_relid = channel->offermsg.child_relid;
 480
 481         if (!channel->is_dedicated_interrupt) {
 482                 /* Each u32 represents 32 channels */
 483                 sync_set_bit(child_relid & 31,
 484                         (unsigned long *)vmbus_connection.send_int_page +
 485                         (child_relid >> 5));
 486         }
 487
 488         return hv_signal_event(channel->sig_event);
 489 }