root/drivers/hv/connection.c

DEFINITIONS

1. vmbus_get_next_version
2. vmbus_negotiate_version
3. vmbus_connect
4. vmbus_disconnect
5. relid2channel
6. vmbus_on_event
7. vmbus_post_msg
8. vmbus_set_event

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