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          * For post win8 hosts, we support receiving channel messagges on
  92          * all the CPUs. This is needed for kexec to work correctly where
  93          * the CPU attempting to connect may not be CPU 0.
  94          */
  95         if (version >= VERSION_WIN8_1) {
  96                 msg->target_vcpu = hv_context.vp_index[get_cpu()];
  97                 put_cpu();
  98         } else {
  99                 msg->target_vcpu = 0;
 100         }
 101
 102         /*
 103          * Add to list before we send the request since we may
 104          * receive the response before returning from this routine
 105          */
 106         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 107         list_add_tail(&msginfo->msglistentry,
 108                       &vmbus_connection.chn_msg_list);
 109
 110         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 111
 112         ret = vmbus_post_msg(msg,
 113                                sizeof(struct vmbus_channel_initiate_contact));
 114         if (ret != 0) {
 115                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 116                 list_del(&msginfo->msglistentry);
 117                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 118                                         flags);
 119                 return ret;
 120         }
 121
 122         /* Wait for the connection response */
 123         wait_for_completion(&msginfo->waitevent);
 124
 125         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 126         list_del(&msginfo->msglistentry);
 127         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 128
 129         /* Check if successful */
 130         if (msginfo->response.version_response.version_supported) {
 131                 vmbus_connection.conn_state = CONNECTED;
 132         } else {
 133                 return -ECONNREFUSED;
 134         }
 135
 136         return ret;
 137 }
 138
 139 /*
 140  * vmbus_connect - Sends a connect request on the partition service connection
 141  */
 142 int vmbus_connect(void)
 143 {
 144         int ret = 0;
 145         struct vmbus_channel_msginfo *msginfo = NULL;
 146         __u32 version;
 147
 148         /* Initialize the vmbus connection */
 149         vmbus_connection.conn_state = CONNECTING;
 150         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 151         if (!vmbus_connection.work_queue) {
 152                 ret = -ENOMEM;
 153                 goto cleanup;
 154         }
 155
 156         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 157         spin_lock_init(&vmbus_connection.channelmsg_lock);
 158
 159         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 160         mutex_init(&vmbus_connection.channel_mutex);
 161
 162         /*
 163          * Setup the vmbus event connection for channel interrupt
 164          * abstraction stuff
 165          */
 166         vmbus_connection.int_page =
 167         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 168         if (vmbus_connection.int_page == NULL) {
 169                 ret = -ENOMEM;
 170                 goto cleanup;
 171         }
 172
 173         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 174         vmbus_connection.send_int_page =
 175                 (void *)((unsigned long)vmbus_connection.int_page +
 176                         (PAGE_SIZE >> 1));
 177
 178         /*
 179          * Setup the monitor notification facility. The 1st page for
 180          * parent->child and the 2nd page for child->parent
 181          */
 182         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 183         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 184         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 185             (vmbus_connection.monitor_pages[1] == NULL)) {
 186                 ret = -ENOMEM;
 187                 goto cleanup;
 188         }
 189
 190         msginfo = kzalloc(sizeof(*msginfo) +
 191                           sizeof(struct vmbus_channel_initiate_contact),
 192                           GFP_KERNEL);
 193         if (msginfo == NULL) {
 194                 ret = -ENOMEM;
 195                 goto cleanup;
 196         }
 197
 198         /*
 199          * Negotiate a compatible VMBUS version number with the
 200          * host. We start with the highest number we can support
 201          * and work our way down until we negotiate a compatible
 202          * version.
 203          */
 204
 205         version = VERSION_CURRENT;
 206
 207         do {
 208                 ret = vmbus_negotiate_version(msginfo, version);
 209                 if (ret == -ETIMEDOUT)
 210                         goto cleanup;
 211
 212                 if (vmbus_connection.conn_state == CONNECTED)
 213                         break;
 214
 215                 version = vmbus_get_next_version(version);
 216         } while (version != VERSION_INVAL);
 217
 218         if (version == VERSION_INVAL)
 219                 goto cleanup;
 220
 221         vmbus_proto_version = version;
 222         pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
 223                     host_info_eax, host_info_ebx >> 16,
 224                     host_info_ebx & 0xFFFF, host_info_ecx,
 225                     host_info_edx >> 24, host_info_edx & 0xFFFFFF,
 226                     version >> 16, version & 0xFFFF);
 227
 228         kfree(msginfo);
 229         return 0;
 230
 231 cleanup:
 232         pr_err("Unable to connect to host\n");
 233
 234         vmbus_connection.conn_state = DISCONNECTED;
 235         vmbus_disconnect();
 236
 237         kfree(msginfo);
 238
 239         return ret;
 240 }
 241
 242 void vmbus_disconnect(void)
 243 {
 244         /*
 245          * First send the unload request to the host.
 246          */
 247         vmbus_initiate_unload(false);
 248
 249         if (vmbus_connection.work_queue) {
 250                 drain_workqueue(vmbus_connection.work_queue);
 251                 destroy_workqueue(vmbus_connection.work_queue);
 252         }
 253
 254         if (vmbus_connection.int_page) {
 255                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 256                 vmbus_connection.int_page = NULL;
 257         }
 258
 259         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 260         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 261         vmbus_connection.monitor_pages[0] = NULL;
 262         vmbus_connection.monitor_pages[1] = NULL;
 263 }
 264
 265 /*
 266  * Map the given relid to the corresponding channel based on the
 267  * per-cpu list of channels that have been affinitized to this CPU.
 268  * This will be used in the channel callback path as we can do this
 269  * mapping in a lock-free fashion.
 270  */
 271 static struct vmbus_channel *pcpu_relid2channel(u32 relid)
 272 {
 273         struct vmbus_channel *channel;
 274         struct vmbus_channel *found_channel  = NULL;
 275         int cpu = smp_processor_id();
 276         struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
 277
 278         list_for_each_entry(channel, pcpu_head, percpu_list) {
 279                 if (channel->offermsg.child_relid == relid) {
 280                         found_channel = channel;
 281                         break;
 282                 }
 283         }
 284
 285         return found_channel;
 286 }
 287
 288 /*
 289  * relid2channel - Get the channel object given its
 290  * child relative id (ie channel id)
 291  */
 292 struct vmbus_channel *relid2channel(u32 relid)
 293 {
 294         struct vmbus_channel *channel;
 295         struct vmbus_channel *found_channel  = NULL;
 296         struct list_head *cur, *tmp;
 297         struct vmbus_channel *cur_sc;
 298
 299         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 300
 301         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 302                 if (channel->offermsg.child_relid == relid) {
 303                         found_channel = channel;
 304                         break;
 305                 } else if (!list_empty(&channel->sc_list)) {
 306                         /*
 307                          * Deal with sub-channels.
 308                          */
 309                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 310                                 cur_sc = list_entry(cur, struct vmbus_channel,
 311                                                         sc_list);
 312                                 if (cur_sc->offermsg.child_relid == relid) {
 313                                         found_channel = cur_sc;
 314                                         break;
 315                                 }
 316                         }
 317                 }
 318         }
 319
 320         return found_channel;
 321 }
 322
 323 /*
 324  * process_chn_event - Process a channel event notification
 325  */
 326 static void process_chn_event(u32 relid)
 327 {
 328         struct vmbus_channel *channel;
 329         void *arg;
 330         bool read_state;
 331         u32 bytes_to_read;
 332
 333         /*
 334          * Find the channel based on this relid and invokes the
 335          * channel callback to process the event
 336          */
 337         channel = pcpu_relid2channel(relid);
 338
 339         if (!channel)
 340                 return;
 341
 342         /*
 343          * A channel once created is persistent even when there
 344          * is no driver handling the device. An unloading driver
 345          * sets the onchannel_callback to NULL on the same CPU
 346          * as where this interrupt is handled (in an interrupt context).
 347          * Thus, checking and invoking the driver specific callback takes
 348          * care of orderly unloading of the driver.
 349          */
 350
 351         if (channel->onchannel_callback != NULL) {
 352                 arg = channel->channel_callback_context;
 353                 read_state = channel->batched_reading;
 354                 /*
 355                  * This callback reads the messages sent by the host.
 356                  * We can optimize host to guest signaling by ensuring:
 357                  * 1. While reading the channel, we disable interrupts from
 358                  *    host.
 359                  * 2. Ensure that we process all posted messages from the host
 360                  *    before returning from this callback.
 361                  * 3. Once we return, enable signaling from the host. Once this
 362                  *    state is set we check to see if additional packets are
 363                  *    available to read. In this case we repeat the process.
 364                  */
 365
 366                 do {
 367                         if (read_state)
 368                                 hv_begin_read(&channel->inbound);
 369                         channel->onchannel_callback(arg);
 370                         if (read_state)
 371                                 bytes_to_read = hv_end_read(&channel->inbound);
 372                         else
 373                                 bytes_to_read = 0;
 374                 } while (read_state && (bytes_to_read != 0));
 375         }
 376 }
 377
 378 /*
 379  * vmbus_on_event - Handler for events
 380  */
 381 void vmbus_on_event(unsigned long data)
 382 {
 383         u32 dword;
 384         u32 maxdword;
 385         int bit;
 386         u32 relid;
 387         u32 *recv_int_page = NULL;
 388         void *page_addr;
 389         int cpu = smp_processor_id();
 390         union hv_synic_event_flags *event;
 391
 392         if (vmbus_proto_version < VERSION_WIN8) {
 393                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 394                 recv_int_page = vmbus_connection.recv_int_page;
 395         } else {
 396                 /*
 397                  * When the host is win8 and beyond, the event page
 398                  * can be directly checked to get the id of the channel
 399                  * that has the interrupt pending.
 400                  */
 401                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 402                 page_addr = hv_context.synic_event_page[cpu];
 403                 event = (union hv_synic_event_flags *)page_addr +
 404                                                  VMBUS_MESSAGE_SINT;
 405                 recv_int_page = event->flags32;
 406         }
 407
 408
 409
 410         /* Check events */
 411         if (!recv_int_page)
 412                 return;
 413         for (dword = 0; dword < maxdword; dword++) {
 414                 if (!recv_int_page[dword])
 415                         continue;
 416                 for (bit = 0; bit < 32; bit++) {
 417                         if (sync_test_and_clear_bit(bit,
 418                                 (unsigned long *)&recv_int_page[dword])) {
 419                                 relid = (dword << 5) + bit;
 420
 421                                 if (relid == 0)
 422                                         /*
 423                                          * Special case - vmbus
 424                                          * channel protocol msg
 425                                          */
 426                                         continue;
 427
 428                                 process_chn_event(relid);
 429                         }
 430                 }
 431         }
 432 }
 433
 434 /*
 435  * vmbus_post_msg - Send a msg on the vmbus's message connection
 436  */
 437 int vmbus_post_msg(void *buffer, size_t buflen)
 438 {
 439         union hv_connection_id conn_id;
 440         int ret = 0;
 441         int retries = 0;
 442         u32 msec = 1;
 443
 444         conn_id.asu32 = 0;
 445         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 446
 447         /*
 448          * hv_post_message() can have transient failures because of
 449          * insufficient resources. Retry the operation a couple of
 450          * times before giving up.
 451          */
 452         while (retries < 20) {
 453                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 454
 455                 switch (ret) {
 456                 case HV_STATUS_INVALID_CONNECTION_ID:
 457                         /*
 458                          * We could get this if we send messages too
 459                          * frequently.
 460                          */
 461                         ret = -EAGAIN;
 462                         break;
 463                 case HV_STATUS_INSUFFICIENT_MEMORY:
 464                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 465                         ret = -ENOMEM;
 466                         break;
 467                 case HV_STATUS_SUCCESS:
 468                         return ret;
 469                 default:
 470                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 471                         return -EINVAL;
 472                 }
 473
 474                 retries++;
 475                 msleep(msec);
 476                 if (msec < 2048)
 477                         msec *= 2;
 478         }
 479         return ret;
 480 }
 481
 482 /*
 483  * vmbus_set_event - Send an event notification to the parent
 484  */
 485 void vmbus_set_event(struct vmbus_channel *channel)
 486 {
 487         u32 child_relid = channel->offermsg.child_relid;
 488
 489         if (!channel->is_dedicated_interrupt) {
 490                 /* Each u32 represents 32 channels */
 491                 sync_set_bit(child_relid & 31,
 492                         (unsigned long *)vmbus_connection.send_int_page +
 493                         (child_relid >> 5));
 494         }
 495
 496         hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
 497 }
 498 EXPORT_SYMBOL_GPL(vmbus_set_event);