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