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         .unload_event           = COMPLETION_INITIALIZER(
  30                                   vmbus_connection.unload_event),
  31         .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),
  32
  33         .ready_for_suspend_event = COMPLETION_INITIALIZER(
  34                                   vmbus_connection.ready_for_suspend_event),
  35         .ready_for_resume_event = COMPLETION_INITIALIZER(
  36                                   vmbus_connection.ready_for_resume_event),
  37 };
  38 EXPORT_SYMBOL_GPL(vmbus_connection);
  39
  40 /*
  41  * Negotiated protocol version with the host.
  42  */
  43 __u32 vmbus_proto_version;
  44 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  45
  46 /*
  47  * Table of VMBus versions listed from newest to oldest.
  48  */
  49 static __u32 vmbus_versions[] = {
  50         VERSION_WIN10_V5_3,
  51         VERSION_WIN10_V5_2,
  52         VERSION_WIN10_V5_1,
  53         VERSION_WIN10_V5,
  54         VERSION_WIN10_V4_1,
  55         VERSION_WIN10,
  56         VERSION_WIN8_1,
  57         VERSION_WIN8,
  58         VERSION_WIN7,
  59         VERSION_WS2008
  60 };
  61
  62 /*
  63  * Maximal VMBus protocol version guests can negotiate.  Useful to cap the
  64  * VMBus version for testing and debugging purpose.
  65  */
  66 static uint max_version = VERSION_WIN10_V5_3;
  67
  68 module_param(max_version, uint, S_IRUGO);
  69 MODULE_PARM_DESC(max_version,
  70                  "Maximal VMBus protocol version which can be negotiated");
  71
  72 int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
  73 {
  74         int ret = 0;
  75         struct vmbus_channel_initiate_contact *msg;
  76         unsigned long flags;
  77
  78         init_completion(&msginfo->waitevent);
  79
  80         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  81
  82         memset(msg, 0, sizeof(*msg));
  83         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  84         msg->vmbus_version_requested = version;
  85
  86         /*
  87          * VMBus protocol 5.0 (VERSION_WIN10_V5) and higher require that we must
  88          * use VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
  89          * and for subsequent messages, we must use the Message Connection ID
  90          * field in the host-returned Version Response Message. And, with
  91          * VERSION_WIN10_V5 and higher, we don't use msg->interrupt_page, but we
  92          * tell the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
  93          * compatibility.
  94          *
  95          * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
  96          */
  97         if (version >= VERSION_WIN10_V5) {
  98                 msg->msg_sint = VMBUS_MESSAGE_SINT;
  99                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
 100         } else {
 101                 msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
 102                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
 103         }
 104
 105         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
 106         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
 107         msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
 108
 109         /*
 110          * Add to list before we send the request since we may
 111          * receive the response before returning from this routine
 112          */
 113         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 114         list_add_tail(&msginfo->msglistentry,
 115                       &vmbus_connection.chn_msg_list);
 116
 117         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 118
 119         ret = vmbus_post_msg(msg,
 120                              sizeof(struct vmbus_channel_initiate_contact),
 121                              true);
 122
 123         trace_vmbus_negotiate_version(msg, ret);
 124
 125         if (ret != 0) {
 126                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 127                 list_del(&msginfo->msglistentry);
 128                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 129                                         flags);
 130                 return ret;
 131         }
 132
 133         /* Wait for the connection response */
 134         wait_for_completion(&msginfo->waitevent);
 135
 136         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 137         list_del(&msginfo->msglistentry);
 138         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 139
 140         /* Check if successful */
 141         if (msginfo->response.version_response.version_supported) {
 142                 vmbus_connection.conn_state = CONNECTED;
 143
 144                 if (version >= VERSION_WIN10_V5)
 145                         vmbus_connection.msg_conn_id =
 146                                 msginfo->response.version_response.msg_conn_id;
 147         } else {
 148                 return -ECONNREFUSED;
 149         }
 150
 151         return ret;
 152 }
 153
 154 /*
 155  * vmbus_connect - Sends a connect request on the partition service connection
 156  */
 157 int vmbus_connect(void)
 158 {
 159         struct vmbus_channel_msginfo *msginfo = NULL;
 160         int i, ret = 0;
 161         __u32 version;
 162
 163         /* Initialize the vmbus connection */
 164         vmbus_connection.conn_state = CONNECTING;
 165         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 166         if (!vmbus_connection.work_queue) {
 167                 ret = -ENOMEM;
 168                 goto cleanup;
 169         }
 170
 171         vmbus_connection.handle_primary_chan_wq =
 172                 create_workqueue("hv_pri_chan");
 173         if (!vmbus_connection.handle_primary_chan_wq) {
 174                 ret = -ENOMEM;
 175                 goto cleanup;
 176         }
 177
 178         vmbus_connection.handle_sub_chan_wq =
 179                 create_workqueue("hv_sub_chan");
 180         if (!vmbus_connection.handle_sub_chan_wq) {
 181                 ret = -ENOMEM;
 182                 goto cleanup;
 183         }
 184
 185         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 186         spin_lock_init(&vmbus_connection.channelmsg_lock);
 187
 188         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 189         mutex_init(&vmbus_connection.channel_mutex);
 190
 191         /*
 192          * Setup the vmbus event connection for channel interrupt
 193          * abstraction stuff
 194          */
 195         vmbus_connection.int_page =
 196         (void *)hv_alloc_hyperv_zeroed_page();
 197         if (vmbus_connection.int_page == NULL) {
 198                 ret = -ENOMEM;
 199                 goto cleanup;
 200         }
 201
 202         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 203         vmbus_connection.send_int_page =
 204                 (void *)((unsigned long)vmbus_connection.int_page +
 205                         (HV_HYP_PAGE_SIZE >> 1));
 206
 207         /*
 208          * Setup the monitor notification facility. The 1st page for
 209          * parent->child and the 2nd page for child->parent
 210          */
 211         vmbus_connection.monitor_pages[0] = (void *)hv_alloc_hyperv_zeroed_page();
 212         vmbus_connection.monitor_pages[1] = (void *)hv_alloc_hyperv_zeroed_page();
 213         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 214             (vmbus_connection.monitor_pages[1] == NULL)) {
 215                 ret = -ENOMEM;
 216                 goto cleanup;
 217         }
 218
 219         msginfo = kzalloc(sizeof(*msginfo) +
 220                           sizeof(struct vmbus_channel_initiate_contact),
 221                           GFP_KERNEL);
 222         if (msginfo == NULL) {
 223                 ret = -ENOMEM;
 224                 goto cleanup;
 225         }
 226
 227         /*
 228          * Negotiate a compatible VMBUS version number with the
 229          * host. We start with the highest number we can support
 230          * and work our way down until we negotiate a compatible
 231          * version.
 232          */
 233
 234         for (i = 0; ; i++) {
 235                 if (i == ARRAY_SIZE(vmbus_versions))
 236                         goto cleanup;
 237
 238                 version = vmbus_versions[i];
 239                 if (version > max_version)
 240                         continue;
 241
 242                 ret = vmbus_negotiate_version(msginfo, version);
 243                 if (ret == -ETIMEDOUT)
 244                         goto cleanup;
 245
 246                 if (vmbus_connection.conn_state == CONNECTED)
 247                         break;
 248         }
 249
 250         if (hv_is_isolation_supported() && version < VERSION_WIN10_V5_2) {
 251                 pr_err("Invalid VMBus version %d.%d (expected >= %d.%d) from the host supporting isolation\n",
 252                        version >> 16, version & 0xFFFF, VERSION_WIN10_V5_2 >> 16, VERSION_WIN10_V5_2 & 0xFFFF);
 253                 ret = -EINVAL;
 254                 goto cleanup;
 255         }
 256
 257         vmbus_proto_version = version;
 258         pr_info("Vmbus version:%d.%d\n",
 259                 version >> 16, version & 0xFFFF);
 260
 261         vmbus_connection.channels = kcalloc(MAX_CHANNEL_RELIDS,
 262                                             sizeof(struct vmbus_channel *),
 263                                             GFP_KERNEL);
 264         if (vmbus_connection.channels == NULL) {
 265                 ret = -ENOMEM;
 266                 goto cleanup;
 267         }
 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         if (WARN_ON(relid >= MAX_CHANNEL_RELIDS))
 317                 return NULL;
 318         return READ_ONCE(vmbus_connection.channels[relid]);
 319 }
 320
 321 /*
 322  * vmbus_on_event - Process a channel event notification
 323  *
 324  * For batched channels (default) optimize host to guest signaling
 325  * by ensuring:
 326  * 1. While reading the channel, we disable interrupts from host.
 327  * 2. Ensure that we process all posted messages from the host
 328  *    before returning from this callback.
 329  * 3. Once we return, enable signaling from the host. Once this
 330  *    state is set we check to see if additional packets are
 331  *    available to read. In this case we repeat the process.
 332  *    If this tasklet has been running for a long time
 333  *    then reschedule ourselves.
 334  */
 335 void vmbus_on_event(unsigned long data)
 336 {
 337         struct vmbus_channel *channel = (void *) data;
 338         unsigned long time_limit = jiffies + 2;
 339
 340         trace_vmbus_on_event(channel);
 341
 342         hv_debug_delay_test(channel, INTERRUPT_DELAY);
 343         do {
 344                 void (*callback_fn)(void *);
 345
 346                 /* A channel once created is persistent even when
 347                  * there is no driver handling the device. An
 348                  * unloading driver sets the onchannel_callback to NULL.
 349                  */
 350                 callback_fn = READ_ONCE(channel->onchannel_callback);
 351                 if (unlikely(callback_fn == NULL))
 352                         return;
 353
 354                 (*callback_fn)(channel->channel_callback_context);
 355
 356                 if (channel->callback_mode != HV_CALL_BATCHED)
 357                         return;
 358
 359                 if (likely(hv_end_read(&channel->inbound) == 0))
 360                         return;
 361
 362                 hv_begin_read(&channel->inbound);
 363         } while (likely(time_before(jiffies, time_limit)));
 364
 365         /* The time limit (2 jiffies) has been reached */
 366         tasklet_schedule(&channel->callback_event);
 367 }
 368
 369 /*
 370  * vmbus_post_msg - Send a msg on the vmbus's message connection
 371  */
 372 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 373 {
 374         struct vmbus_channel_message_header *hdr;
 375         union hv_connection_id conn_id;
 376         int ret = 0;
 377         int retries = 0;
 378         u32 usec = 1;
 379
 380         conn_id.asu32 = 0;
 381         conn_id.u.id = vmbus_connection.msg_conn_id;
 382
 383         /*
 384          * hv_post_message() can have transient failures because of
 385          * insufficient resources. Retry the operation a couple of
 386          * times before giving up.
 387          */
 388         while (retries < 100) {
 389                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 390
 391                 switch (ret) {
 392                 case HV_STATUS_INVALID_CONNECTION_ID:
 393                         /*
 394                          * See vmbus_negotiate_version(): VMBus protocol 5.0
 395                          * and higher require that we must use
 396                          * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
 397                          * Contact message, but on old hosts that only
 398                          * support VMBus protocol 4.0 or lower, here we get
 399                          * HV_STATUS_INVALID_CONNECTION_ID and we should
 400                          * return an error immediately without retrying.
 401                          */
 402                         hdr = buffer;
 403                         if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
 404                                 return -EINVAL;
 405                         /*
 406                          * We could get this if we send messages too
 407                          * frequently.
 408                          */
 409                         ret = -EAGAIN;
 410                         break;
 411                 case HV_STATUS_INSUFFICIENT_MEMORY:
 412                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 413                         ret = -ENOBUFS;
 414                         break;
 415                 case HV_STATUS_SUCCESS:
 416                         return ret;
 417                 default:
 418                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 419                         return -EINVAL;
 420                 }
 421
 422                 retries++;
 423                 if (can_sleep && usec > 1000)
 424                         msleep(usec / 1000);
 425                 else if (usec < MAX_UDELAY_MS * 1000)
 426                         udelay(usec);
 427                 else
 428                         mdelay(usec / 1000);
 429
 430                 if (retries < 22)
 431                         usec *= 2;
 432         }
 433         return ret;
 434 }
 435
 436 /*
 437  * vmbus_set_event - Send an event notification to the parent
 438  */
 439 void vmbus_set_event(struct vmbus_channel *channel)
 440 {
 441         u32 child_relid = channel->offermsg.child_relid;
 442
 443         if (!channel->is_dedicated_interrupt)
 444                 vmbus_send_interrupt(child_relid);
 445
 446         ++channel->sig_events;
 447
 448         hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 449 }
 450 EXPORT_SYMBOL_GPL(vmbus_set_event);