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         unsigned int cur_cpu;
  80         struct vmbus_channel_initiate_contact *msg;
  81         unsigned long flags;
  82
  83         init_completion(&msginfo->waitevent);
  84
  85         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  86
  87         memset(msg, 0, sizeof(*msg));
  88         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  89         msg->vmbus_version_requested = version;
  90
  91         /*
  92          * VMBus protocol 5.0 (VERSION_WIN10_V5) requires that we must use
  93          * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
  94          * and for subsequent messages, we must use the Message Connection ID
  95          * field in the host-returned Version Response Message. And, with
  96          * VERSION_WIN10_V5, we don't use msg->interrupt_page, but we tell
  97          * the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
  98          * compatibility.
  99          *
 100          * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
 101          */
 102         if (version >= VERSION_WIN10_V5) {
 103                 msg->msg_sint = VMBUS_MESSAGE_SINT;
 104                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
 105         } else {
 106                 msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
 107                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
 108         }
 109
 110         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
 111         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
 112         /*
 113          * We want all channel messages to be delivered on CPU 0.
 114          * This has been the behavior pre-win8. This is not
 115          * perf issue and having all channel messages delivered on CPU 0
 116          * would be ok.
 117          * For post win8 hosts, we support receiving channel messagges on
 118          * all the CPUs. This is needed for kexec to work correctly where
 119          * the CPU attempting to connect may not be CPU 0.
 120          */
 121         if (version >= VERSION_WIN8_1) {
 122                 cur_cpu = get_cpu();
 123                 msg->target_vcpu = hv_cpu_number_to_vp_number(cur_cpu);
 124                 vmbus_connection.connect_cpu = cur_cpu;
 125                 put_cpu();
 126         } else {
 127                 msg->target_vcpu = 0;
 128                 vmbus_connection.connect_cpu = 0;
 129         }
 130
 131         /*
 132          * Add to list before we send the request since we may
 133          * receive the response before returning from this routine
 134          */
 135         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 136         list_add_tail(&msginfo->msglistentry,
 137                       &vmbus_connection.chn_msg_list);
 138
 139         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 140
 141         ret = vmbus_post_msg(msg,
 142                              sizeof(struct vmbus_channel_initiate_contact),
 143                              true);
 144
 145         trace_vmbus_negotiate_version(msg, ret);
 146
 147         if (ret != 0) {
 148                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 149                 list_del(&msginfo->msglistentry);
 150                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 151                                         flags);
 152                 return ret;
 153         }
 154
 155         /* Wait for the connection response */
 156         wait_for_completion(&msginfo->waitevent);
 157
 158         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 159         list_del(&msginfo->msglistentry);
 160         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 161
 162         /* Check if successful */
 163         if (msginfo->response.version_response.version_supported) {
 164                 vmbus_connection.conn_state = CONNECTED;
 165
 166                 if (version >= VERSION_WIN10_V5)
 167                         vmbus_connection.msg_conn_id =
 168                                 msginfo->response.version_response.msg_conn_id;
 169         } else {
 170                 return -ECONNREFUSED;
 171         }
 172
 173         return ret;
 174 }
 175
 176 /*
 177  * vmbus_connect - Sends a connect request on the partition service connection
 178  */
 179 int vmbus_connect(void)
 180 {
 181         int ret = 0;
 182         struct vmbus_channel_msginfo *msginfo = NULL;
 183         __u32 version;
 184
 185         /* Initialize the vmbus connection */
 186         vmbus_connection.conn_state = CONNECTING;
 187         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 188         if (!vmbus_connection.work_queue) {
 189                 ret = -ENOMEM;
 190                 goto cleanup;
 191         }
 192
 193         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 194         spin_lock_init(&vmbus_connection.channelmsg_lock);
 195
 196         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 197         mutex_init(&vmbus_connection.channel_mutex);
 198
 199         /*
 200          * Setup the vmbus event connection for channel interrupt
 201          * abstraction stuff
 202          */
 203         vmbus_connection.int_page =
 204         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 205         if (vmbus_connection.int_page == NULL) {
 206                 ret = -ENOMEM;
 207                 goto cleanup;
 208         }
 209
 210         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 211         vmbus_connection.send_int_page =
 212                 (void *)((unsigned long)vmbus_connection.int_page +
 213                         (PAGE_SIZE >> 1));
 214
 215         /*
 216          * Setup the monitor notification facility. The 1st page for
 217          * parent->child and the 2nd page for child->parent
 218          */
 219         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 220         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 221         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 222             (vmbus_connection.monitor_pages[1] == NULL)) {
 223                 ret = -ENOMEM;
 224                 goto cleanup;
 225         }
 226
 227         msginfo = kzalloc(sizeof(*msginfo) +
 228                           sizeof(struct vmbus_channel_initiate_contact),
 229                           GFP_KERNEL);
 230         if (msginfo == NULL) {
 231                 ret = -ENOMEM;
 232                 goto cleanup;
 233         }
 234
 235         /*
 236          * Negotiate a compatible VMBUS version number with the
 237          * host. We start with the highest number we can support
 238          * and work our way down until we negotiate a compatible
 239          * version.
 240          */
 241
 242         version = VERSION_CURRENT;
 243
 244         do {
 245                 ret = vmbus_negotiate_version(msginfo, version);
 246                 if (ret == -ETIMEDOUT)
 247                         goto cleanup;
 248
 249                 if (vmbus_connection.conn_state == CONNECTED)
 250                         break;
 251
 252                 version = vmbus_get_next_version(version);
 253         } while (version != VERSION_INVAL);
 254
 255         if (version == VERSION_INVAL)
 256                 goto cleanup;
 257
 258         vmbus_proto_version = version;
 259         pr_info("Vmbus version:%d.%d\n",
 260                 version >> 16, version & 0xFFFF);
 261
 262         kfree(msginfo);
 263         return 0;
 264
 265 cleanup:
 266         pr_err("Unable to connect to host\n");
 267
 268         vmbus_connection.conn_state = DISCONNECTED;
 269         vmbus_disconnect();
 270
 271         kfree(msginfo);
 272
 273         return ret;
 274 }
 275
 276 void vmbus_disconnect(void)
 277 {
 278         /*
 279          * First send the unload request to the host.
 280          */
 281         vmbus_initiate_unload(false);
 282
 283         if (vmbus_connection.work_queue) {
 284                 drain_workqueue(vmbus_connection.work_queue);
 285                 destroy_workqueue(vmbus_connection.work_queue);
 286         }
 287
 288         if (vmbus_connection.int_page) {
 289                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 290                 vmbus_connection.int_page = NULL;
 291         }
 292
 293         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 294         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 295         vmbus_connection.monitor_pages[0] = NULL;
 296         vmbus_connection.monitor_pages[1] = NULL;
 297 }
 298
 299 /*
 300  * relid2channel - Get the channel object given its
 301  * child relative id (ie channel id)
 302  */
 303 struct vmbus_channel *relid2channel(u32 relid)
 304 {
 305         struct vmbus_channel *channel;
 306         struct vmbus_channel *found_channel  = NULL;
 307         struct list_head *cur, *tmp;
 308         struct vmbus_channel *cur_sc;
 309
 310         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 311
 312         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 313                 if (channel->offermsg.child_relid == relid) {
 314                         found_channel = channel;
 315                         break;
 316                 } else if (!list_empty(&channel->sc_list)) {
 317                         /*
 318                          * Deal with sub-channels.
 319                          */
 320                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 321                                 cur_sc = list_entry(cur, struct vmbus_channel,
 322                                                         sc_list);
 323                                 if (cur_sc->offermsg.child_relid == relid) {
 324                                         found_channel = cur_sc;
 325                                         break;
 326                                 }
 327                         }
 328                 }
 329         }
 330
 331         return found_channel;
 332 }
 333
 334 /*
 335  * vmbus_on_event - Process a channel event notification
 336  *
 337  * For batched channels (default) optimize host to guest signaling
 338  * by ensuring:
 339  * 1. While reading the channel, we disable interrupts from host.
 340  * 2. Ensure that we process all posted messages from the host
 341  *    before returning from this callback.
 342  * 3. Once we return, enable signaling from the host. Once this
 343  *    state is set we check to see if additional packets are
 344  *    available to read. In this case we repeat the process.
 345  *    If this tasklet has been running for a long time
 346  *    then reschedule ourselves.
 347  */
 348 void vmbus_on_event(unsigned long data)
 349 {
 350         struct vmbus_channel *channel = (void *) data;
 351         unsigned long time_limit = jiffies + 2;
 352
 353         trace_vmbus_on_event(channel);
 354
 355         do {
 356                 void (*callback_fn)(void *);
 357
 358                 /* A channel once created is persistent even when
 359                  * there is no driver handling the device. An
 360                  * unloading driver sets the onchannel_callback to NULL.
 361                  */
 362                 callback_fn = READ_ONCE(channel->onchannel_callback);
 363                 if (unlikely(callback_fn == NULL))
 364                         return;
 365
 366                 (*callback_fn)(channel->channel_callback_context);
 367
 368                 if (channel->callback_mode != HV_CALL_BATCHED)
 369                         return;
 370
 371                 if (likely(hv_end_read(&channel->inbound) == 0))
 372                         return;
 373
 374                 hv_begin_read(&channel->inbound);
 375         } while (likely(time_before(jiffies, time_limit)));
 376
 377         /* The time limit (2 jiffies) has been reached */
 378         tasklet_schedule(&channel->callback_event);
 379 }
 380
 381 /*
 382  * vmbus_post_msg - Send a msg on the vmbus's message connection
 383  */
 384 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 385 {
 386         struct vmbus_channel_message_header *hdr;
 387         union hv_connection_id conn_id;
 388         int ret = 0;
 389         int retries = 0;
 390         u32 usec = 1;
 391
 392         conn_id.asu32 = 0;
 393         conn_id.u.id = vmbus_connection.msg_conn_id;
 394
 395         /*
 396          * hv_post_message() can have transient failures because of
 397          * insufficient resources. Retry the operation a couple of
 398          * times before giving up.
 399          */
 400         while (retries < 100) {
 401                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 402
 403                 switch (ret) {
 404                 case HV_STATUS_INVALID_CONNECTION_ID:
 405                         /*
 406                          * See vmbus_negotiate_version(): VMBus protocol 5.0
 407                          * requires that we must use
 408                          * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
 409                          * Contact message, but on old hosts that only
 410                          * support VMBus protocol 4.0 or lower, here we get
 411                          * HV_STATUS_INVALID_CONNECTION_ID and we should
 412                          * return an error immediately without retrying.
 413                          */
 414                         hdr = buffer;
 415                         if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
 416                                 return -EINVAL;
 417                         /*
 418                          * We could get this if we send messages too
 419                          * frequently.
 420                          */
 421                         ret = -EAGAIN;
 422                         break;
 423                 case HV_STATUS_INSUFFICIENT_MEMORY:
 424                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 425                         ret = -ENOBUFS;
 426                         break;
 427                 case HV_STATUS_SUCCESS:
 428                         return ret;
 429                 default:
 430                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 431                         return -EINVAL;
 432                 }
 433
 434                 retries++;
 435                 if (can_sleep && usec > 1000)
 436                         msleep(usec / 1000);
 437                 else if (usec < MAX_UDELAY_MS * 1000)
 438                         udelay(usec);
 439                 else
 440                         mdelay(usec / 1000);
 441
 442                 if (retries < 22)
 443                         usec *= 2;
 444         }
 445         return ret;
 446 }
 447
 448 /*
 449  * vmbus_set_event - Send an event notification to the parent
 450  */
 451 void vmbus_set_event(struct vmbus_channel *channel)
 452 {
 453         u32 child_relid = channel->offermsg.child_relid;
 454
 455         if (!channel->is_dedicated_interrupt)
 456                 vmbus_send_interrupt(child_relid);
 457
 458         ++channel->sig_events;
 459
 460         hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 461 }
 462 EXPORT_SYMBOL_GPL(vmbus_set_event);