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                         goto cleanup;
 234
 235                 version = vmbus_versions[i];
 236                 if (version > max_version)
 237                         continue;
 238
 239                 ret = vmbus_negotiate_version(msginfo, version);
 240                 if (ret == -ETIMEDOUT)
 241                         goto cleanup;
 242
 243                 if (vmbus_connection.conn_state == CONNECTED)
 244                         break;
 245         }
 246
 247         vmbus_proto_version = version;
 248         pr_info("Vmbus version:%d.%d\n",
 249                 version >> 16, version & 0xFFFF);
 250
 251         vmbus_connection.channels = kcalloc(MAX_CHANNEL_RELIDS,
 252                                             sizeof(struct vmbus_channel *),
 253                                             GFP_KERNEL);
 254         if (vmbus_connection.channels == NULL) {
 255                 ret = -ENOMEM;
 256                 goto cleanup;
 257         }
 258
 259         kfree(msginfo);
 260         return 0;
 261
 262 cleanup:
 263         pr_err("Unable to connect to host\n");
 264
 265         vmbus_connection.conn_state = DISCONNECTED;
 266         vmbus_disconnect();
 267
 268         kfree(msginfo);
 269
 270         return ret;
 271 }
 272
 273 void vmbus_disconnect(void)
 274 {
 275         /*
 276          * First send the unload request to the host.
 277          */
 278         vmbus_initiate_unload(false);
 279
 280         if (vmbus_connection.handle_sub_chan_wq)
 281                 destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
 282
 283         if (vmbus_connection.handle_primary_chan_wq)
 284                 destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
 285
 286         if (vmbus_connection.work_queue)
 287                 destroy_workqueue(vmbus_connection.work_queue);
 288
 289         if (vmbus_connection.int_page) {
 290                 hv_free_hyperv_page((unsigned long)vmbus_connection.int_page);
 291                 vmbus_connection.int_page = NULL;
 292         }
 293
 294         hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[0]);
 295         hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[1]);
 296         vmbus_connection.monitor_pages[0] = NULL;
 297         vmbus_connection.monitor_pages[1] = NULL;
 298 }
 299
 300 /*
 301  * relid2channel - Get the channel object given its
 302  * child relative id (ie channel id)
 303  */
 304 struct vmbus_channel *relid2channel(u32 relid)
 305 {
 306         if (WARN_ON(relid >= MAX_CHANNEL_RELIDS))
 307                 return NULL;
 308         return READ_ONCE(vmbus_connection.channels[relid]);
 309 }
 310
 311 /*
 312  * vmbus_on_event - Process a channel event notification
 313  *
 314  * For batched channels (default) optimize host to guest signaling
 315  * by ensuring:
 316  * 1. While reading the channel, we disable interrupts from host.
 317  * 2. Ensure that we process all posted messages from the host
 318  *    before returning from this callback.
 319  * 3. Once we return, enable signaling from the host. Once this
 320  *    state is set we check to see if additional packets are
 321  *    available to read. In this case we repeat the process.
 322  *    If this tasklet has been running for a long time
 323  *    then reschedule ourselves.
 324  */
 325 void vmbus_on_event(unsigned long data)
 326 {
 327         struct vmbus_channel *channel = (void *) data;
 328         unsigned long time_limit = jiffies + 2;
 329
 330         trace_vmbus_on_event(channel);
 331
 332         hv_debug_delay_test(channel, INTERRUPT_DELAY);
 333         do {
 334                 void (*callback_fn)(void *);
 335
 336                 /* A channel once created is persistent even when
 337                  * there is no driver handling the device. An
 338                  * unloading driver sets the onchannel_callback to NULL.
 339                  */
 340                 callback_fn = READ_ONCE(channel->onchannel_callback);
 341                 if (unlikely(callback_fn == NULL))
 342                         return;
 343
 344                 (*callback_fn)(channel->channel_callback_context);
 345
 346                 if (channel->callback_mode != HV_CALL_BATCHED)
 347                         return;
 348
 349                 if (likely(hv_end_read(&channel->inbound) == 0))
 350                         return;
 351
 352                 hv_begin_read(&channel->inbound);
 353         } while (likely(time_before(jiffies, time_limit)));
 354
 355         /* The time limit (2 jiffies) has been reached */
 356         tasklet_schedule(&channel->callback_event);
 357 }
 358
 359 /*
 360  * vmbus_post_msg - Send a msg on the vmbus's message connection
 361  */
 362 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 363 {
 364         struct vmbus_channel_message_header *hdr;
 365         union hv_connection_id conn_id;
 366         int ret = 0;
 367         int retries = 0;
 368         u32 usec = 1;
 369
 370         conn_id.asu32 = 0;
 371         conn_id.u.id = vmbus_connection.msg_conn_id;
 372
 373         /*
 374          * hv_post_message() can have transient failures because of
 375          * insufficient resources. Retry the operation a couple of
 376          * times before giving up.
 377          */
 378         while (retries < 100) {
 379                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 380
 381                 switch (ret) {
 382                 case HV_STATUS_INVALID_CONNECTION_ID:
 383                         /*
 384                          * See vmbus_negotiate_version(): VMBus protocol 5.0
 385                          * and higher require that we must use
 386                          * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
 387                          * Contact message, but on old hosts that only
 388                          * support VMBus protocol 4.0 or lower, here we get
 389                          * HV_STATUS_INVALID_CONNECTION_ID and we should
 390                          * return an error immediately without retrying.
 391                          */
 392                         hdr = buffer;
 393                         if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
 394                                 return -EINVAL;
 395                         /*
 396                          * We could get this if we send messages too
 397                          * frequently.
 398                          */
 399                         ret = -EAGAIN;
 400                         break;
 401                 case HV_STATUS_INSUFFICIENT_MEMORY:
 402                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 403                         ret = -ENOBUFS;
 404                         break;
 405                 case HV_STATUS_SUCCESS:
 406                         return ret;
 407                 default:
 408                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 409                         return -EINVAL;
 410                 }
 411
 412                 retries++;
 413                 if (can_sleep && usec > 1000)
 414                         msleep(usec / 1000);
 415                 else if (usec < MAX_UDELAY_MS * 1000)
 416                         udelay(usec);
 417                 else
 418                         mdelay(usec / 1000);
 419
 420                 if (retries < 22)
 421                         usec *= 2;
 422         }
 423         return ret;
 424 }
 425
 426 /*
 427  * vmbus_set_event - Send an event notification to the parent
 428  */
 429 void vmbus_set_event(struct vmbus_channel *channel)
 430 {
 431         u32 child_relid = channel->offermsg.child_relid;
 432
 433         if (!channel->is_dedicated_interrupt)
 434                 vmbus_send_interrupt(child_relid);
 435
 436         ++channel->sig_events;
 437
 438         hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 439 }
 440 EXPORT_SYMBOL_GPL(vmbus_set_event);