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/module.h>
  18 #include <linux/slab.h>
  19 #include <linux/vmalloc.h>
  20 #include <linux/hyperv.h>
  21 #include <linux/export.h>
  22 #include <asm/mshyperv.h>
  23
  24 #include "hyperv_vmbus.h"
  25
  26
  27 struct vmbus_connection vmbus_connection = {
  28         .conn_state             = DISCONNECTED,
  29         .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),
  30
  31         .ready_for_suspend_event= COMPLETION_INITIALIZER(
  32                                   vmbus_connection.ready_for_suspend_event),
  33         .ready_for_resume_event = COMPLETION_INITIALIZER(
  34                                   vmbus_connection.ready_for_resume_event),
  35 };
  36 EXPORT_SYMBOL_GPL(vmbus_connection);
  37
  38 /*
  39  * Negotiated protocol version with the host.
  40  */
  41 __u32 vmbus_proto_version;
  42 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  43
  44 /*
  45  * Table of VMBus versions listed from newest to oldest.
  46  */
  47 static __u32 vmbus_versions[] = {
  48         VERSION_WIN10_V5_2,
  49         VERSION_WIN10_V5_1,
  50         VERSION_WIN10_V5,
  51         VERSION_WIN10_V4_1,
  52         VERSION_WIN10,
  53         VERSION_WIN8_1,
  54         VERSION_WIN8,
  55         VERSION_WIN7,
  56         VERSION_WS2008
  57 };
  58
  59 /*
  60  * Maximal VMBus protocol version guests can negotiate.  Useful to cap the
  61  * VMBus version for testing and debugging purpose.
  62  */
  63 static uint max_version = VERSION_WIN10_V5_2;
  64
  65 module_param(max_version, uint, S_IRUGO);
  66 MODULE_PARM_DESC(max_version,
  67                  "Maximal VMBus protocol version which can be negotiated");
  68
  69 int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
  70 {
  71         int ret = 0;
  72         unsigned int cur_cpu;
  73         struct vmbus_channel_initiate_contact *msg;
  74         unsigned long flags;
  75
  76         init_completion(&msginfo->waitevent);
  77
  78         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  79
  80         memset(msg, 0, sizeof(*msg));
  81         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  82         msg->vmbus_version_requested = version;
  83
  84         /*
  85          * VMBus protocol 5.0 (VERSION_WIN10_V5) and higher require that we must
  86          * use VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
  87          * and for subsequent messages, we must use the Message Connection ID
  88          * field in the host-returned Version Response Message. And, with
  89          * VERSION_WIN10_V5 and higher, we don't use msg->interrupt_page, but we
  90          * tell the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
  91          * compatibility.
  92          *
  93          * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
  94          */
  95         if (version >= VERSION_WIN10_V5) {
  96                 msg->msg_sint = VMBUS_MESSAGE_SINT;
  97                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
  98         } else {
  99                 msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
 100                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
 101         }
 102
 103         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
 104         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
 105         /*
 106          * We want all channel messages to be delivered on CPU 0.
 107          * This has been the behavior pre-win8. This is not
 108          * perf issue and having all channel messages delivered on CPU 0
 109          * would be ok.
 110          * For post win8 hosts, we support receiving channel messagges on
 111          * all the CPUs. This is needed for kexec to work correctly where
 112          * the CPU attempting to connect may not be CPU 0.
 113          */
 114         if (version >= VERSION_WIN8_1) {
 115                 cur_cpu = get_cpu();
 116                 msg->target_vcpu = hv_cpu_number_to_vp_number(cur_cpu);
 117                 vmbus_connection.connect_cpu = cur_cpu;
 118                 put_cpu();
 119         } else {
 120                 msg->target_vcpu = 0;
 121                 vmbus_connection.connect_cpu = 0;
 122         }
 123
 124         /*
 125          * Add to list before we send the request since we may
 126          * receive the response before returning from this routine
 127          */
 128         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 129         list_add_tail(&msginfo->msglistentry,
 130                       &vmbus_connection.chn_msg_list);
 131
 132         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 133
 134         ret = vmbus_post_msg(msg,
 135                              sizeof(struct vmbus_channel_initiate_contact),
 136                              true);
 137
 138         trace_vmbus_negotiate_version(msg, ret);
 139
 140         if (ret != 0) {
 141                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 142                 list_del(&msginfo->msglistentry);
 143                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 144                                         flags);
 145                 return ret;
 146         }
 147
 148         /* Wait for the connection response */
 149         wait_for_completion(&msginfo->waitevent);
 150
 151         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 152         list_del(&msginfo->msglistentry);
 153         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 154
 155         /* Check if successful */
 156         if (msginfo->response.version_response.version_supported) {
 157                 vmbus_connection.conn_state = CONNECTED;
 158
 159                 if (version >= VERSION_WIN10_V5)
 160                         vmbus_connection.msg_conn_id =
 161                                 msginfo->response.version_response.msg_conn_id;
 162         } else {
 163                 return -ECONNREFUSED;
 164         }
 165
 166         return ret;
 167 }
 168
 169 /*
 170  * vmbus_connect - Sends a connect request on the partition service connection
 171  */
 172 int vmbus_connect(void)
 173 {
 174         struct vmbus_channel_msginfo *msginfo = NULL;
 175         int i, ret = 0;
 176         __u32 version;
 177
 178         /* Initialize the vmbus connection */
 179         vmbus_connection.conn_state = CONNECTING;
 180         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 181         if (!vmbus_connection.work_queue) {
 182                 ret = -ENOMEM;
 183                 goto cleanup;
 184         }
 185
 186         vmbus_connection.handle_primary_chan_wq =
 187                 create_workqueue("hv_pri_chan");
 188         if (!vmbus_connection.handle_primary_chan_wq) {
 189                 ret = -ENOMEM;
 190                 goto cleanup;
 191         }
 192
 193         vmbus_connection.handle_sub_chan_wq =
 194                 create_workqueue("hv_sub_chan");
 195         if (!vmbus_connection.handle_sub_chan_wq) {
 196                 ret = -ENOMEM;
 197                 goto cleanup;
 198         }
 199
 200         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 201         spin_lock_init(&vmbus_connection.channelmsg_lock);
 202
 203         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 204         mutex_init(&vmbus_connection.channel_mutex);
 205
 206         /*
 207          * Setup the vmbus event connection for channel interrupt
 208          * abstraction stuff
 209          */
 210         vmbus_connection.int_page =
 211         (void *)hv_alloc_hyperv_zeroed_page();
 212         if (vmbus_connection.int_page == NULL) {
 213                 ret = -ENOMEM;
 214                 goto cleanup;
 215         }
 216
 217         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 218         vmbus_connection.send_int_page =
 219                 (void *)((unsigned long)vmbus_connection.int_page +
 220                         (HV_HYP_PAGE_SIZE >> 1));
 221
 222         /*
 223          * Setup the monitor notification facility. The 1st page for
 224          * parent->child and the 2nd page for child->parent
 225          */
 226         vmbus_connection.monitor_pages[0] = (void *)hv_alloc_hyperv_zeroed_page();
 227         vmbus_connection.monitor_pages[1] = (void *)hv_alloc_hyperv_zeroed_page();
 228         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 229             (vmbus_connection.monitor_pages[1] == NULL)) {
 230                 ret = -ENOMEM;
 231                 goto cleanup;
 232         }
 233
 234         msginfo = kzalloc(sizeof(*msginfo) +
 235                           sizeof(struct vmbus_channel_initiate_contact),
 236                           GFP_KERNEL);
 237         if (msginfo == NULL) {
 238                 ret = -ENOMEM;
 239                 goto cleanup;
 240         }
 241
 242         /*
 243          * Negotiate a compatible VMBUS version number with the
 244          * host. We start with the highest number we can support
 245          * and work our way down until we negotiate a compatible
 246          * version.
 247          */
 248
 249         for (i = 0; ; i++) {
 250                 if (i == ARRAY_SIZE(vmbus_versions))
 251                         goto cleanup;
 252
 253                 version = vmbus_versions[i];
 254                 if (version > max_version)
 255                         continue;
 256
 257                 ret = vmbus_negotiate_version(msginfo, version);
 258                 if (ret == -ETIMEDOUT)
 259                         goto cleanup;
 260
 261                 if (vmbus_connection.conn_state == CONNECTED)
 262                         break;
 263         }
 264
 265         vmbus_proto_version = version;
 266         pr_info("Vmbus version:%d.%d\n",
 267                 version >> 16, version & 0xFFFF);
 268
 269         kfree(msginfo);
 270         return 0;
 271
 272 cleanup:
 273         pr_err("Unable to connect to host\n");
 274
 275         vmbus_connection.conn_state = DISCONNECTED;
 276         vmbus_disconnect();
 277
 278         kfree(msginfo);
 279
 280         return ret;
 281 }
 282
 283 void vmbus_disconnect(void)
 284 {
 285         /*
 286          * First send the unload request to the host.
 287          */
 288         vmbus_initiate_unload(false);
 289
 290         if (vmbus_connection.handle_sub_chan_wq)
 291                 destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
 292
 293         if (vmbus_connection.handle_primary_chan_wq)
 294                 destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
 295
 296         if (vmbus_connection.work_queue)
 297                 destroy_workqueue(vmbus_connection.work_queue);
 298
 299         if (vmbus_connection.int_page) {
 300                 hv_free_hyperv_page((unsigned long)vmbus_connection.int_page);
 301                 vmbus_connection.int_page = NULL;
 302         }
 303
 304         hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[0]);
 305         hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[1]);
 306         vmbus_connection.monitor_pages[0] = NULL;
 307         vmbus_connection.monitor_pages[1] = NULL;
 308 }
 309
 310 /*
 311  * relid2channel - Get the channel object given its
 312  * child relative id (ie channel id)
 313  */
 314 struct vmbus_channel *relid2channel(u32 relid)
 315 {
 316         struct vmbus_channel *channel;
 317         struct vmbus_channel *found_channel  = NULL;
 318         struct list_head *cur, *tmp;
 319         struct vmbus_channel *cur_sc;
 320
 321         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 322
 323         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 324                 if (channel->offermsg.child_relid == relid) {
 325                         found_channel = channel;
 326                         break;
 327                 } else if (!list_empty(&channel->sc_list)) {
 328                         /*
 329                          * Deal with sub-channels.
 330                          */
 331                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 332                                 cur_sc = list_entry(cur, struct vmbus_channel,
 333                                                         sc_list);
 334                                 if (cur_sc->offermsg.child_relid == relid) {
 335                                         found_channel = cur_sc;
 336                                         break;
 337                                 }
 338                         }
 339                 }
 340         }
 341
 342         return found_channel;
 343 }
 344
 345 /*
 346  * vmbus_on_event - Process a channel event notification
 347  *
 348  * For batched channels (default) optimize host to guest signaling
 349  * by ensuring:
 350  * 1. While reading the channel, we disable interrupts from host.
 351  * 2. Ensure that we process all posted messages from the host
 352  *    before returning from this callback.
 353  * 3. Once we return, enable signaling from the host. Once this
 354  *    state is set we check to see if additional packets are
 355  *    available to read. In this case we repeat the process.
 356  *    If this tasklet has been running for a long time
 357  *    then reschedule ourselves.
 358  */
 359 void vmbus_on_event(unsigned long data)
 360 {
 361         struct vmbus_channel *channel = (void *) data;
 362         unsigned long time_limit = jiffies + 2;
 363
 364         trace_vmbus_on_event(channel);
 365
 366         hv_debug_delay_test(channel, INTERRUPT_DELAY);
 367         do {
 368                 void (*callback_fn)(void *);
 369
 370                 /* A channel once created is persistent even when
 371                  * there is no driver handling the device. An
 372                  * unloading driver sets the onchannel_callback to NULL.
 373                  */
 374                 callback_fn = READ_ONCE(channel->onchannel_callback);
 375                 if (unlikely(callback_fn == NULL))
 376                         return;
 377
 378                 (*callback_fn)(channel->channel_callback_context);
 379
 380                 if (channel->callback_mode != HV_CALL_BATCHED)
 381                         return;
 382
 383                 if (likely(hv_end_read(&channel->inbound) == 0))
 384                         return;
 385
 386                 hv_begin_read(&channel->inbound);
 387         } while (likely(time_before(jiffies, time_limit)));
 388
 389         /* The time limit (2 jiffies) has been reached */
 390         tasklet_schedule(&channel->callback_event);
 391 }
 392
 393 /*
 394  * vmbus_post_msg - Send a msg on the vmbus's message connection
 395  */
 396 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 397 {
 398         struct vmbus_channel_message_header *hdr;
 399         union hv_connection_id conn_id;
 400         int ret = 0;
 401         int retries = 0;
 402         u32 usec = 1;
 403
 404         conn_id.asu32 = 0;
 405         conn_id.u.id = vmbus_connection.msg_conn_id;
 406
 407         /*
 408          * hv_post_message() can have transient failures because of
 409          * insufficient resources. Retry the operation a couple of
 410          * times before giving up.
 411          */
 412         while (retries < 100) {
 413                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 414
 415                 switch (ret) {
 416                 case HV_STATUS_INVALID_CONNECTION_ID:
 417                         /*
 418                          * See vmbus_negotiate_version(): VMBus protocol 5.0
 419                          * and higher require that we must use
 420                          * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
 421                          * Contact message, but on old hosts that only
 422                          * support VMBus protocol 4.0 or lower, here we get
 423                          * HV_STATUS_INVALID_CONNECTION_ID and we should
 424                          * return an error immediately without retrying.
 425                          */
 426                         hdr = buffer;
 427                         if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
 428                                 return -EINVAL;
 429                         /*
 430                          * We could get this if we send messages too
 431                          * frequently.
 432                          */
 433                         ret = -EAGAIN;
 434                         break;
 435                 case HV_STATUS_INSUFFICIENT_MEMORY:
 436                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 437                         ret = -ENOBUFS;
 438                         break;
 439                 case HV_STATUS_SUCCESS:
 440                         return ret;
 441                 default:
 442                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 443                         return -EINVAL;
 444                 }
 445
 446                 retries++;
 447                 if (can_sleep && usec > 1000)
 448                         msleep(usec / 1000);
 449                 else if (usec < MAX_UDELAY_MS * 1000)
 450                         udelay(usec);
 451                 else
 452                         mdelay(usec / 1000);
 453
 454                 if (retries < 22)
 455                         usec *= 2;
 456         }
 457         return ret;
 458 }
 459
 460 /*
 461  * vmbus_set_event - Send an event notification to the parent
 462  */
 463 void vmbus_set_event(struct vmbus_channel *channel)
 464 {
 465         u32 child_relid = channel->offermsg.child_relid;
 466
 467         if (!channel->is_dedicated_interrupt)
 468                 vmbus_send_interrupt(child_relid);
 469
 470         ++channel->sig_events;
 471
 472         hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 473 }
 474 EXPORT_SYMBOL_GPL(vmbus_set_event);