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("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
 225                     host_info_eax, host_info_ebx >> 16,
 226                     host_info_ebx & 0xFFFF, host_info_ecx,
 227                     host_info_edx >> 24, host_info_edx & 0xFFFFFF,
 228                     version >> 16, version & 0xFFFF);
 229
 230         kfree(msginfo);
 231         return 0;
 232
 233 cleanup:
 234         pr_err("Unable to connect to host\n");
 235
 236         vmbus_connection.conn_state = DISCONNECTED;
 237         vmbus_disconnect();
 238
 239         kfree(msginfo);
 240
 241         return ret;
 242 }
 243
 244 void vmbus_disconnect(void)
 245 {
 246         /*
 247          * First send the unload request to the host.
 248          */
 249         vmbus_initiate_unload(false);
 250
 251         if (vmbus_connection.work_queue) {
 252                 drain_workqueue(vmbus_connection.work_queue);
 253                 destroy_workqueue(vmbus_connection.work_queue);
 254         }
 255
 256         if (vmbus_connection.int_page) {
 257                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 258                 vmbus_connection.int_page = NULL;
 259         }
 260
 261         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 262         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 263         vmbus_connection.monitor_pages[0] = NULL;
 264         vmbus_connection.monitor_pages[1] = NULL;
 265 }
 266
 267 /*
 268  * Map the given relid to the corresponding channel based on the
 269  * per-cpu list of channels that have been affinitized to this CPU.
 270  * This will be used in the channel callback path as we can do this
 271  * mapping in a lock-free fashion.
 272  */
 273 static struct vmbus_channel *pcpu_relid2channel(u32 relid)
 274 {
 275         struct vmbus_channel *channel;
 276         struct vmbus_channel *found_channel  = NULL;
 277         int cpu = smp_processor_id();
 278         struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
 279
 280         list_for_each_entry(channel, pcpu_head, percpu_list) {
 281                 if (channel->offermsg.child_relid == relid) {
 282                         found_channel = channel;
 283                         break;
 284                 }
 285         }
 286
 287         return found_channel;
 288 }
 289
 290 /*
 291  * relid2channel - Get the channel object given its
 292  * child relative id (ie channel id)
 293  */
 294 struct vmbus_channel *relid2channel(u32 relid)
 295 {
 296         struct vmbus_channel *channel;
 297         struct vmbus_channel *found_channel  = NULL;
 298         struct list_head *cur, *tmp;
 299         struct vmbus_channel *cur_sc;
 300
 301         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 302
 303         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 304                 if (channel->offermsg.child_relid == relid) {
 305                         found_channel = channel;
 306                         break;
 307                 } else if (!list_empty(&channel->sc_list)) {
 308                         /*
 309                          * Deal with sub-channels.
 310                          */
 311                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 312                                 cur_sc = list_entry(cur, struct vmbus_channel,
 313                                                         sc_list);
 314                                 if (cur_sc->offermsg.child_relid == relid) {
 315                                         found_channel = cur_sc;
 316                                         break;
 317                                 }
 318                         }
 319                 }
 320         }
 321
 322         return found_channel;
 323 }
 324
 325 /*
 326  * process_chn_event - Process a channel event notification
 327  */
 328 static void process_chn_event(u32 relid)
 329 {
 330         struct vmbus_channel *channel;
 331         void *arg;
 332         bool read_state;
 333         u32 bytes_to_read;
 334
 335         /*
 336          * Find the channel based on this relid and invokes the
 337          * channel callback to process the event
 338          */
 339         channel = pcpu_relid2channel(relid);
 340
 341         if (!channel)
 342                 return;
 343
 344         /*
 345          * A channel once created is persistent even when there
 346          * is no driver handling the device. An unloading driver
 347          * sets the onchannel_callback to NULL on the same CPU
 348          * as where this interrupt is handled (in an interrupt context).
 349          * Thus, checking and invoking the driver specific callback takes
 350          * care of orderly unloading of the driver.
 351          */
 352
 353         if (channel->onchannel_callback != NULL) {
 354                 arg = channel->channel_callback_context;
 355                 read_state = channel->batched_reading;
 356                 /*
 357                  * This callback reads the messages sent by the host.
 358                  * We can optimize host to guest signaling by ensuring:
 359                  * 1. While reading the channel, we disable interrupts from
 360                  *    host.
 361                  * 2. Ensure that we process all posted messages from the host
 362                  *    before returning from this callback.
 363                  * 3. Once we return, enable signaling from the host. Once this
 364                  *    state is set we check to see if additional packets are
 365                  *    available to read. In this case we repeat the process.
 366                  */
 367
 368                 do {
 369                         if (read_state)
 370                                 hv_begin_read(&channel->inbound);
 371                         channel->onchannel_callback(arg);
 372                         if (read_state)
 373                                 bytes_to_read = hv_end_read(&channel->inbound);
 374                         else
 375                                 bytes_to_read = 0;
 376                 } while (read_state && (bytes_to_read != 0));
 377         }
 378 }
 379
 380 /*
 381  * vmbus_on_event - Handler for events
 382  */
 383 void vmbus_on_event(unsigned long data)
 384 {
 385         u32 dword;
 386         u32 maxdword;
 387         int bit;
 388         u32 relid;
 389         u32 *recv_int_page = NULL;
 390         void *page_addr;
 391         int cpu = smp_processor_id();
 392         union hv_synic_event_flags *event;
 393
 394         if (vmbus_proto_version < VERSION_WIN8) {
 395                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 396                 recv_int_page = vmbus_connection.recv_int_page;
 397         } else {
 398                 /*
 399                  * When the host is win8 and beyond, the event page
 400                  * can be directly checked to get the id of the channel
 401                  * that has the interrupt pending.
 402                  */
 403                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 404                 page_addr = hv_context.synic_event_page[cpu];
 405                 event = (union hv_synic_event_flags *)page_addr +
 406                                                  VMBUS_MESSAGE_SINT;
 407                 recv_int_page = event->flags32;
 408         }
 409
 410
 411
 412         /* Check events */
 413         if (!recv_int_page)
 414                 return;
 415         for (dword = 0; dword < maxdword; dword++) {
 416                 if (!recv_int_page[dword])
 417                         continue;
 418                 for (bit = 0; bit < 32; bit++) {
 419                         if (sync_test_and_clear_bit(bit,
 420                                 (unsigned long *)&recv_int_page[dword])) {
 421                                 relid = (dword << 5) + bit;
 422
 423                                 if (relid == 0)
 424                                         /*
 425                                          * Special case - vmbus
 426                                          * channel protocol msg
 427                                          */
 428                                         continue;
 429
 430                                 process_chn_event(relid);
 431                         }
 432                 }
 433         }
 434 }
 435
 436 /*
 437  * vmbus_post_msg - Send a msg on the vmbus's message connection
 438  */
 439 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 440 {
 441         union hv_connection_id conn_id;
 442         int ret = 0;
 443         int retries = 0;
 444         u32 usec = 1;
 445
 446         conn_id.asu32 = 0;
 447         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 448
 449         /*
 450          * hv_post_message() can have transient failures because of
 451          * insufficient resources. Retry the operation a couple of
 452          * times before giving up.
 453          */
 454         while (retries < 100) {
 455                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 456
 457                 switch (ret) {
 458                 case HV_STATUS_INVALID_CONNECTION_ID:
 459                         /*
 460                          * We could get this if we send messages too
 461                          * frequently.
 462                          */
 463                         ret = -EAGAIN;
 464                         break;
 465                 case HV_STATUS_INSUFFICIENT_MEMORY:
 466                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 467                         ret = -ENOMEM;
 468                         break;
 469                 case HV_STATUS_SUCCESS:
 470                         return ret;
 471                 default:
 472                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 473                         return -EINVAL;
 474                 }
 475
 476                 retries++;
 477                 if (can_sleep && usec > 1000)
 478                         msleep(usec / 1000);
 479                 else if (usec < MAX_UDELAY_MS * 1000)
 480                         udelay(usec);
 481                 else
 482                         mdelay(usec / 1000);
 483
 484                 if (usec < 256000)
 485                         usec *= 2;
 486         }
 487         return ret;
 488 }
 489
 490 /*
 491  * vmbus_set_event - Send an event notification to the parent
 492  */
 493 void vmbus_set_event(struct vmbus_channel *channel)
 494 {
 495         u32 child_relid = channel->offermsg.child_relid;
 496
 497         if (!channel->is_dedicated_interrupt) {
 498                 /* Each u32 represents 32 channels */
 499                 sync_set_bit(child_relid & 31,
 500                         (unsigned long *)vmbus_connection.send_int_page +
 501                         (child_relid >> 5));
 502         }
 503
 504         hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
 505 }
 506 EXPORT_SYMBOL_GPL(vmbus_set_event);