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/mshyperv.h>
  35
  36 #include "hyperv_vmbus.h"
  37
  38
  39 struct vmbus_connection vmbus_connection = {
  40         .conn_state             = DISCONNECTED,
  41         .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),
  42 };
  43 EXPORT_SYMBOL_GPL(vmbus_connection);
  44
  45 /*
  46  * Negotiated protocol version with the host.
  47  */
  48 __u32 vmbus_proto_version;
  49 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  50
  51 static __u32 vmbus_get_next_version(__u32 current_version)
  52 {
  53         switch (current_version) {
  54         case (VERSION_WIN7):
  55                 return VERSION_WS2008;
  56
  57         case (VERSION_WIN8):
  58                 return VERSION_WIN7;
  59
  60         case (VERSION_WIN8_1):
  61                 return VERSION_WIN8;
  62
  63         case (VERSION_WIN10):
  64                 return VERSION_WIN8_1;
  65
  66         case (VERSION_WIN10_V5):
  67                 return VERSION_WIN10;
  68
  69         case (VERSION_WS2008):
  70         default:
  71                 return VERSION_INVAL;
  72         }
  73 }
  74
  75 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  76                                         __u32 version)
  77 {
  78         int ret = 0;
  79         struct vmbus_channel_initiate_contact *msg;
  80         unsigned long flags;
  81
  82         init_completion(&msginfo->waitevent);
  83
  84         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  85
  86         memset(msg, 0, sizeof(*msg));
  87         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  88         msg->vmbus_version_requested = version;
  89
  90         /*
  91          * VMBus protocol 5.0 (VERSION_WIN10_V5) requires that we must use
  92          * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
  93          * and for subsequent messages, we must use the Message Connection ID
  94          * field in the host-returned Version Response Message. And, with
  95          * VERSION_WIN10_V5, we don't use msg->interrupt_page, but we tell
  96          * the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
  97          * compatibility.
  98          *
  99          * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
 100          */
 101         if (version >= VERSION_WIN10_V5) {
 102                 msg->msg_sint = VMBUS_MESSAGE_SINT;
 103                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
 104         } else {
 105                 msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
 106                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
 107         }
 108
 109         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
 110         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
 111         /*
 112          * We want all channel messages to be delivered on CPU 0.
 113          * This has been the behavior pre-win8. This is not
 114          * perf issue and having all channel messages delivered on CPU 0
 115          * would be ok.
 116          * For post win8 hosts, we support receiving channel messagges on
 117          * all the CPUs. This is needed for kexec to work correctly where
 118          * the CPU attempting to connect may not be CPU 0.
 119          */
 120         if (version >= VERSION_WIN8_1) {
 121                 msg->target_vcpu =
 122                         hv_cpu_number_to_vp_number(smp_processor_id());
 123                 vmbus_connection.connect_cpu = smp_processor_id();
 124         } else {
 125                 msg->target_vcpu = 0;
 126                 vmbus_connection.connect_cpu = 0;
 127         }
 128
 129         /*
 130          * Add to list before we send the request since we may
 131          * receive the response before returning from this routine
 132          */
 133         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 134         list_add_tail(&msginfo->msglistentry,
 135                       &vmbus_connection.chn_msg_list);
 136
 137         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 138
 139         ret = vmbus_post_msg(msg,
 140                              sizeof(struct vmbus_channel_initiate_contact),
 141                              true);
 142
 143         trace_vmbus_negotiate_version(msg, ret);
 144
 145         if (ret != 0) {
 146                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 147                 list_del(&msginfo->msglistentry);
 148                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 149                                         flags);
 150                 return ret;
 151         }
 152
 153         /* Wait for the connection response */
 154         wait_for_completion(&msginfo->waitevent);
 155
 156         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 157         list_del(&msginfo->msglistentry);
 158         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 159
 160         /* Check if successful */
 161         if (msginfo->response.version_response.version_supported) {
 162                 vmbus_connection.conn_state = CONNECTED;
 163
 164                 if (version >= VERSION_WIN10_V5)
 165                         vmbus_connection.msg_conn_id =
 166                                 msginfo->response.version_response.msg_conn_id;
 167         } else {
 168                 return -ECONNREFUSED;
 169         }
 170
 171         return ret;
 172 }
 173
 174 /*
 175  * vmbus_connect - Sends a connect request on the partition service connection
 176  */
 177 int vmbus_connect(void)
 178 {
 179         int ret = 0;
 180         struct vmbus_channel_msginfo *msginfo = NULL;
 181         __u32 version;
 182
 183         /* Initialize the vmbus connection */
 184         vmbus_connection.conn_state = CONNECTING;
 185         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 186         if (!vmbus_connection.work_queue) {
 187                 ret = -ENOMEM;
 188                 goto cleanup;
 189         }
 190
 191         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 192         spin_lock_init(&vmbus_connection.channelmsg_lock);
 193
 194         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 195         mutex_init(&vmbus_connection.channel_mutex);
 196
 197         /*
 198          * Setup the vmbus event connection for channel interrupt
 199          * abstraction stuff
 200          */
 201         vmbus_connection.int_page =
 202         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 203         if (vmbus_connection.int_page == NULL) {
 204                 ret = -ENOMEM;
 205                 goto cleanup;
 206         }
 207
 208         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 209         vmbus_connection.send_int_page =
 210                 (void *)((unsigned long)vmbus_connection.int_page +
 211                         (PAGE_SIZE >> 1));
 212
 213         /*
 214          * Setup the monitor notification facility. The 1st page for
 215          * parent->child and the 2nd page for child->parent
 216          */
 217         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 218         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 219         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 220             (vmbus_connection.monitor_pages[1] == NULL)) {
 221                 ret = -ENOMEM;
 222                 goto cleanup;
 223         }
 224
 225         msginfo = kzalloc(sizeof(*msginfo) +
 226                           sizeof(struct vmbus_channel_initiate_contact),
 227                           GFP_KERNEL);
 228         if (msginfo == NULL) {
 229                 ret = -ENOMEM;
 230                 goto cleanup;
 231         }
 232
 233         /*
 234          * Negotiate a compatible VMBUS version number with the
 235          * host. We start with the highest number we can support
 236          * and work our way down until we negotiate a compatible
 237          * version.
 238          */
 239
 240         version = VERSION_CURRENT;
 241
 242         do {
 243                 ret = vmbus_negotiate_version(msginfo, version);
 244                 if (ret == -ETIMEDOUT)
 245                         goto cleanup;
 246
 247                 if (vmbus_connection.conn_state == CONNECTED)
 248                         break;
 249
 250                 version = vmbus_get_next_version(version);
 251         } while (version != VERSION_INVAL);
 252
 253         if (version == VERSION_INVAL)
 254                 goto cleanup;
 255
 256         vmbus_proto_version = version;
 257         pr_info("Vmbus version:%d.%d\n",
 258                 version >> 16, version & 0xFFFF);
 259
 260         kfree(msginfo);
 261         return 0;
 262
 263 cleanup:
 264         pr_err("Unable to connect to host\n");
 265
 266         vmbus_connection.conn_state = DISCONNECTED;
 267         vmbus_disconnect();
 268
 269         kfree(msginfo);
 270
 271         return ret;
 272 }
 273
 274 void vmbus_disconnect(void)
 275 {
 276         /*
 277          * First send the unload request to the host.
 278          */
 279         vmbus_initiate_unload(false);
 280
 281         if (vmbus_connection.work_queue) {
 282                 drain_workqueue(vmbus_connection.work_queue);
 283                 destroy_workqueue(vmbus_connection.work_queue);
 284         }
 285
 286         if (vmbus_connection.int_page) {
 287                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 288                 vmbus_connection.int_page = NULL;
 289         }
 290
 291         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 292         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 293         vmbus_connection.monitor_pages[0] = NULL;
 294         vmbus_connection.monitor_pages[1] = NULL;
 295 }
 296
 297 /*
 298  * relid2channel - Get the channel object given its
 299  * child relative id (ie channel id)
 300  */
 301 struct vmbus_channel *relid2channel(u32 relid)
 302 {
 303         struct vmbus_channel *channel;
 304         struct vmbus_channel *found_channel  = NULL;
 305         struct list_head *cur, *tmp;
 306         struct vmbus_channel *cur_sc;
 307
 308         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 309
 310         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 311                 if (channel->offermsg.child_relid == relid) {
 312                         found_channel = channel;
 313                         break;
 314                 } else if (!list_empty(&channel->sc_list)) {
 315                         /*
 316                          * Deal with sub-channels.
 317                          */
 318                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 319                                 cur_sc = list_entry(cur, struct vmbus_channel,
 320                                                         sc_list);
 321                                 if (cur_sc->offermsg.child_relid == relid) {
 322                                         found_channel = cur_sc;
 323                                         break;
 324                                 }
 325                         }
 326                 }
 327         }
 328
 329         return found_channel;
 330 }
 331
 332 /*
 333  * vmbus_on_event - Process a channel event notification
 334  *
 335  * For batched channels (default) optimize host to guest signaling
 336  * by ensuring:
 337  * 1. While reading the channel, we disable interrupts from host.
 338  * 2. Ensure that we process all posted messages from the host
 339  *    before returning from this callback.
 340  * 3. Once we return, enable signaling from the host. Once this
 341  *    state is set we check to see if additional packets are
 342  *    available to read. In this case we repeat the process.
 343  *    If this tasklet has been running for a long time
 344  *    then reschedule ourselves.
 345  */
 346 void vmbus_on_event(unsigned long data)
 347 {
 348         struct vmbus_channel *channel = (void *) data;
 349         unsigned long time_limit = jiffies + 2;
 350
 351         trace_vmbus_on_event(channel);
 352
 353         do {
 354                 void (*callback_fn)(void *);
 355
 356                 /* A channel once created is persistent even when
 357                  * there is no driver handling the device. An
 358                  * unloading driver sets the onchannel_callback to NULL.
 359                  */
 360                 callback_fn = READ_ONCE(channel->onchannel_callback);
 361                 if (unlikely(callback_fn == NULL))
 362                         return;
 363
 364                 (*callback_fn)(channel->channel_callback_context);
 365
 366                 if (channel->callback_mode != HV_CALL_BATCHED)
 367                         return;
 368
 369                 if (likely(hv_end_read(&channel->inbound) == 0))
 370                         return;
 371
 372                 hv_begin_read(&channel->inbound);
 373         } while (likely(time_before(jiffies, time_limit)));
 374
 375         /* The time limit (2 jiffies) has been reached */
 376         tasklet_schedule(&channel->callback_event);
 377 }
 378
 379 /*
 380  * vmbus_post_msg - Send a msg on the vmbus's message connection
 381  */
 382 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 383 {
 384         struct vmbus_channel_message_header *hdr;
 385         union hv_connection_id conn_id;
 386         int ret = 0;
 387         int retries = 0;
 388         u32 usec = 1;
 389
 390         conn_id.asu32 = 0;
 391         conn_id.u.id = vmbus_connection.msg_conn_id;
 392
 393         /*
 394          * hv_post_message() can have transient failures because of
 395          * insufficient resources. Retry the operation a couple of
 396          * times before giving up.
 397          */
 398         while (retries < 100) {
 399                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 400
 401                 switch (ret) {
 402                 case HV_STATUS_INVALID_CONNECTION_ID:
 403                         /*
 404                          * See vmbus_negotiate_version(): VMBus protocol 5.0
 405                          * requires that we must use
 406                          * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
 407                          * Contact message, but on old hosts that only
 408                          * support VMBus protocol 4.0 or lower, here we get
 409                          * HV_STATUS_INVALID_CONNECTION_ID and we should
 410                          * return an error immediately without retrying.
 411                          */
 412                         hdr = buffer;
 413                         if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
 414                                 return -EINVAL;
 415                         /*
 416                          * We could get this if we send messages too
 417                          * frequently.
 418                          */
 419                         ret = -EAGAIN;
 420                         break;
 421                 case HV_STATUS_INSUFFICIENT_MEMORY:
 422                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 423                         ret = -ENOBUFS;
 424                         break;
 425                 case HV_STATUS_SUCCESS:
 426                         return ret;
 427                 default:
 428                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 429                         return -EINVAL;
 430                 }
 431
 432                 retries++;
 433                 if (can_sleep && usec > 1000)
 434                         msleep(usec / 1000);
 435                 else if (usec < MAX_UDELAY_MS * 1000)
 436                         udelay(usec);
 437                 else
 438                         mdelay(usec / 1000);
 439
 440                 if (retries < 22)
 441                         usec *= 2;
 442         }
 443         return ret;
 444 }
 445
 446 /*
 447  * vmbus_set_event - Send an event notification to the parent
 448  */
 449 void vmbus_set_event(struct vmbus_channel *channel)
 450 {
 451         u32 child_relid = channel->offermsg.child_relid;
 452
 453         if (!channel->is_dedicated_interrupt)
 454                 vmbus_send_interrupt(child_relid);
 455
 456         ++channel->sig_events;
 457
 458         hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 459 }
 460 EXPORT_SYMBOL_GPL(vmbus_set_event);