drivers/hv/connection.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *
   4  * Copyright (c) 2009, Microsoft Corporation.
   5  *
   6  * Authors:
   7  *   Haiyang Zhang <haiyangz@microsoft.com>
   8  *   Hank Janssen  <hjanssen@microsoft.com>
   9  */
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/kernel.h>
  13 #include <linux/sched.h>
  14 #include <linux/wait.h>
  15 #include <linux/delay.h>
  16 #include <linux/mm.h>
  17 #include <linux/slab.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/hyperv.h>
  20 #include <linux/export.h>
  21 #include <asm/mshyperv.h>
  22
  23 #include "hyperv_vmbus.h"
  24
  25
  26 struct vmbus_connection vmbus_connection = {
  27         .conn_state             = DISCONNECTED,
  28         .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),
  29 };
  30 EXPORT_SYMBOL_GPL(vmbus_connection);
  31
  32 /*
  33  * Negotiated protocol version with the host.
  34  */
  35 __u32 vmbus_proto_version;
  36 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  37
  38 static __u32 vmbus_get_next_version(__u32 current_version)
  39 {
  40         switch (current_version) {
  41         case (VERSION_WIN7):
  42                 return VERSION_WS2008;
  43
  44         case (VERSION_WIN8):
  45                 return VERSION_WIN7;
  46
  47         case (VERSION_WIN8_1):
  48                 return VERSION_WIN8;
  49
  50         case (VERSION_WIN10):
  51                 return VERSION_WIN8_1;
  52
  53         case (VERSION_WIN10_V5):
  54                 return VERSION_WIN10;
  55
  56         case (VERSION_WS2008):
  57         default:
  58                 return VERSION_INVAL;
  59         }
  60 }
  61
  62 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  63                                         __u32 version)
  64 {
  65         int ret = 0;
  66         unsigned int cur_cpu;
  67         struct vmbus_channel_initiate_contact *msg;
  68         unsigned long flags;
  69
  70         init_completion(&msginfo->waitevent);
  71
  72         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  73
  74         memset(msg, 0, sizeof(*msg));
  75         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  76         msg->vmbus_version_requested = version;
  77
  78         /*
  79          * VMBus protocol 5.0 (VERSION_WIN10_V5) requires that we must use
  80          * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
  81          * and for subsequent messages, we must use the Message Connection ID
  82          * field in the host-returned Version Response Message. And, with
  83          * VERSION_WIN10_V5, we don't use msg->interrupt_page, but we tell
  84          * the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
  85          * compatibility.
  86          *
  87          * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
  88          */
  89         if (version >= VERSION_WIN10_V5) {
  90                 msg->msg_sint = VMBUS_MESSAGE_SINT;
  91                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
  92         } else {
  93                 msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  94                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
  95         }
  96
  97         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
  98         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
  99         /*
 100          * We want all channel messages to be delivered on CPU 0.
 101          * This has been the behavior pre-win8. This is not
 102          * perf issue and having all channel messages delivered on CPU 0
 103          * would be ok.
 104          * For post win8 hosts, we support receiving channel messagges on
 105          * all the CPUs. This is needed for kexec to work correctly where
 106          * the CPU attempting to connect may not be CPU 0.
 107          */
 108         if (version >= VERSION_WIN8_1) {
 109                 cur_cpu = get_cpu();
 110                 msg->target_vcpu = hv_cpu_number_to_vp_number(cur_cpu);
 111                 vmbus_connection.connect_cpu = cur_cpu;
 112                 put_cpu();
 113         } else {
 114                 msg->target_vcpu = 0;
 115                 vmbus_connection.connect_cpu = 0;
 116         }
 117
 118         /*
 119          * Add to list before we send the request since we may
 120          * receive the response before returning from this routine
 121          */
 122         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 123         list_add_tail(&msginfo->msglistentry,
 124                       &vmbus_connection.chn_msg_list);
 125
 126         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 127
 128         ret = vmbus_post_msg(msg,
 129                              sizeof(struct vmbus_channel_initiate_contact),
 130                              true);
 131
 132         trace_vmbus_negotiate_version(msg, ret);
 133
 134         if (ret != 0) {
 135                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 136                 list_del(&msginfo->msglistentry);
 137                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 138                                         flags);
 139                 return ret;
 140         }
 141
 142         /* Wait for the connection response */
 143         wait_for_completion(&msginfo->waitevent);
 144
 145         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 146         list_del(&msginfo->msglistentry);
 147         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 148
 149         /* Check if successful */
 150         if (msginfo->response.version_response.version_supported) {
 151                 vmbus_connection.conn_state = CONNECTED;
 152
 153                 if (version >= VERSION_WIN10_V5)
 154                         vmbus_connection.msg_conn_id =
 155                                 msginfo->response.version_response.msg_conn_id;
 156         } else {
 157                 return -ECONNREFUSED;
 158         }
 159
 160         return ret;
 161 }
 162
 163 /*
 164  * vmbus_connect - Sends a connect request on the partition service connection
 165  */
 166 int vmbus_connect(void)
 167 {
 168         int ret = 0;
 169         struct vmbus_channel_msginfo *msginfo = NULL;
 170         __u32 version;
 171
 172         /* Initialize the vmbus connection */
 173         vmbus_connection.conn_state = CONNECTING;
 174         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 175         if (!vmbus_connection.work_queue) {
 176                 ret = -ENOMEM;
 177                 goto cleanup;
 178         }
 179
 180         vmbus_connection.handle_primary_chan_wq =
 181                 create_workqueue("hv_pri_chan");
 182         if (!vmbus_connection.handle_primary_chan_wq) {
 183                 ret = -ENOMEM;
 184                 goto cleanup;
 185         }
 186
 187         vmbus_connection.handle_sub_chan_wq =
 188                 create_workqueue("hv_sub_chan");
 189         if (!vmbus_connection.handle_sub_chan_wq) {
 190                 ret = -ENOMEM;
 191                 goto cleanup;
 192         }
 193
 194         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 195         spin_lock_init(&vmbus_connection.channelmsg_lock);
 196
 197         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 198         mutex_init(&vmbus_connection.channel_mutex);
 199
 200         /*
 201          * Setup the vmbus event connection for channel interrupt
 202          * abstraction stuff
 203          */
 204         vmbus_connection.int_page =
 205         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 206         if (vmbus_connection.int_page == NULL) {
 207                 ret = -ENOMEM;
 208                 goto cleanup;
 209         }
 210
 211         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 212         vmbus_connection.send_int_page =
 213                 (void *)((unsigned long)vmbus_connection.int_page +
 214                         (PAGE_SIZE >> 1));
 215
 216         /*
 217          * Setup the monitor notification facility. The 1st page for
 218          * parent->child and the 2nd page for child->parent
 219          */
 220         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 221         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 222         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 223             (vmbus_connection.monitor_pages[1] == NULL)) {
 224                 ret = -ENOMEM;
 225                 goto cleanup;
 226         }
 227
 228         msginfo = kzalloc(sizeof(*msginfo) +
 229                           sizeof(struct vmbus_channel_initiate_contact),
 230                           GFP_KERNEL);
 231         if (msginfo == NULL) {
 232                 ret = -ENOMEM;
 233                 goto cleanup;
 234         }
 235
 236         /*
 237          * Negotiate a compatible VMBUS version number with the
 238          * host. We start with the highest number we can support
 239          * and work our way down until we negotiate a compatible
 240          * version.
 241          */
 242
 243         version = VERSION_CURRENT;
 244
 245         do {
 246                 ret = vmbus_negotiate_version(msginfo, version);
 247                 if (ret == -ETIMEDOUT)
 248                         goto cleanup;
 249
 250                 if (vmbus_connection.conn_state == CONNECTED)
 251                         break;
 252
 253                 version = vmbus_get_next_version(version);
 254         } while (version != VERSION_INVAL);
 255
 256         if (version == VERSION_INVAL)
 257                 goto cleanup;
 258
 259         vmbus_proto_version = version;
 260         pr_info("Vmbus version:%d.%d\n",
 261                 version >> 16, version & 0xFFFF);
 262
 263         kfree(msginfo);
 264         return 0;
 265
 266 cleanup:
 267         pr_err("Unable to connect to host\n");
 268
 269         vmbus_connection.conn_state = DISCONNECTED;
 270         vmbus_disconnect();
 271
 272         kfree(msginfo);
 273
 274         return ret;
 275 }
 276
 277 void vmbus_disconnect(void)
 278 {
 279         /*
 280          * First send the unload request to the host.
 281          */
 282         vmbus_initiate_unload(false);
 283
 284         if (vmbus_connection.handle_sub_chan_wq)
 285                 destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
 286
 287         if (vmbus_connection.handle_primary_chan_wq)
 288                 destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
 289
 290         if (vmbus_connection.work_queue)
 291                 destroy_workqueue(vmbus_connection.work_queue);
 292
 293         if (vmbus_connection.int_page) {
 294                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 295                 vmbus_connection.int_page = NULL;
 296         }
 297
 298         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 299         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 300         vmbus_connection.monitor_pages[0] = NULL;
 301         vmbus_connection.monitor_pages[1] = NULL;
 302 }
 303
 304 /*
 305  * relid2channel - Get the channel object given its
 306  * child relative id (ie channel id)
 307  */
 308 struct vmbus_channel *relid2channel(u32 relid)
 309 {
 310         struct vmbus_channel *channel;
 311         struct vmbus_channel *found_channel  = NULL;
 312         struct list_head *cur, *tmp;
 313         struct vmbus_channel *cur_sc;
 314
 315         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 316
 317         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 318                 if (channel->offermsg.child_relid == relid) {
 319                         found_channel = channel;
 320                         break;
 321                 } else if (!list_empty(&channel->sc_list)) {
 322                         /*
 323                          * Deal with sub-channels.
 324                          */
 325                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 326                                 cur_sc = list_entry(cur, struct vmbus_channel,
 327                                                         sc_list);
 328                                 if (cur_sc->offermsg.child_relid == relid) {
 329                                         found_channel = cur_sc;
 330                                         break;
 331                                 }
 332                         }
 333                 }
 334         }
 335
 336         return found_channel;
 337 }
 338
 339 /*
 340  * vmbus_on_event - Process a channel event notification
 341  *
 342  * For batched channels (default) optimize host to guest signaling
 343  * by ensuring:
 344  * 1. While reading the channel, we disable interrupts from host.
 345  * 2. Ensure that we process all posted messages from the host
 346  *    before returning from this callback.
 347  * 3. Once we return, enable signaling from the host. Once this
 348  *    state is set we check to see if additional packets are
 349  *    available to read. In this case we repeat the process.
 350  *    If this tasklet has been running for a long time
 351  *    then reschedule ourselves.
 352  */
 353 void vmbus_on_event(unsigned long data)
 354 {
 355         struct vmbus_channel *channel = (void *) data;
 356         unsigned long time_limit = jiffies + 2;
 357
 358         trace_vmbus_on_event(channel);
 359
 360         do {
 361                 void (*callback_fn)(void *);
 362
 363                 /* A channel once created is persistent even when
 364                  * there is no driver handling the device. An
 365                  * unloading driver sets the onchannel_callback to NULL.
 366                  */
 367                 callback_fn = READ_ONCE(channel->onchannel_callback);
 368                 if (unlikely(callback_fn == NULL))
 369                         return;
 370
 371                 (*callback_fn)(channel->channel_callback_context);
 372
 373                 if (channel->callback_mode != HV_CALL_BATCHED)
 374                         return;
 375
 376                 if (likely(hv_end_read(&channel->inbound) == 0))
 377                         return;
 378
 379                 hv_begin_read(&channel->inbound);
 380         } while (likely(time_before(jiffies, time_limit)));
 381
 382         /* The time limit (2 jiffies) has been reached */
 383         tasklet_schedule(&channel->callback_event);
 384 }
 385
 386 /*
 387  * vmbus_post_msg - Send a msg on the vmbus's message connection
 388  */
 389 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 390 {
 391         struct vmbus_channel_message_header *hdr;
 392         union hv_connection_id conn_id;
 393         int ret = 0;
 394         int retries = 0;
 395         u32 usec = 1;
 396
 397         conn_id.asu32 = 0;
 398         conn_id.u.id = vmbus_connection.msg_conn_id;
 399
 400         /*
 401          * hv_post_message() can have transient failures because of
 402          * insufficient resources. Retry the operation a couple of
 403          * times before giving up.
 404          */
 405         while (retries < 100) {
 406                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 407
 408                 switch (ret) {
 409                 case HV_STATUS_INVALID_CONNECTION_ID:
 410                         /*
 411                          * See vmbus_negotiate_version(): VMBus protocol 5.0
 412                          * requires that we must use
 413                          * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
 414                          * Contact message, but on old hosts that only
 415                          * support VMBus protocol 4.0 or lower, here we get
 416                          * HV_STATUS_INVALID_CONNECTION_ID and we should
 417                          * return an error immediately without retrying.
 418                          */
 419                         hdr = buffer;
 420                         if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
 421                                 return -EINVAL;
 422                         /*
 423                          * We could get this if we send messages too
 424                          * frequently.
 425                          */
 426                         ret = -EAGAIN;
 427                         break;
 428                 case HV_STATUS_INSUFFICIENT_MEMORY:
 429                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 430                         ret = -ENOBUFS;
 431                         break;
 432                 case HV_STATUS_SUCCESS:
 433                         return ret;
 434                 default:
 435                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 436                         return -EINVAL;
 437                 }
 438
 439                 retries++;
 440                 if (can_sleep && usec > 1000)
 441                         msleep(usec / 1000);
 442                 else if (usec < MAX_UDELAY_MS * 1000)
 443                         udelay(usec);
 444                 else
 445                         mdelay(usec / 1000);
 446
 447                 if (retries < 22)
 448                         usec *= 2;
 449         }
 450         return ret;
 451 }
 452
 453 /*
 454  * vmbus_set_event - Send an event notification to the parent
 455  */
 456 void vmbus_set_event(struct vmbus_channel *channel)
 457 {
 458         u32 child_relid = channel->offermsg.child_relid;
 459
 460         if (!channel->is_dedicated_interrupt)
 461                 vmbus_send_interrupt(child_relid);
 462
 463         ++channel->sig_events;
 464
 465         hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 466 }
 467 EXPORT_SYMBOL_GPL(vmbus_set_event);