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 <linux/io.h>
  23 #include <linux/set_memory.h>
  24 #include <asm/mshyperv.h>
  25
  26 #include "hyperv_vmbus.h"
  27
  28
  29 struct vmbus_connection vmbus_connection = {
  30         .conn_state             = DISCONNECTED,
  31         .unload_event           = COMPLETION_INITIALIZER(
  32                                   vmbus_connection.unload_event),
  33         .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),
  34
  35         .ready_for_suspend_event = COMPLETION_INITIALIZER(
  36                                   vmbus_connection.ready_for_suspend_event),
  37         .ready_for_resume_event = COMPLETION_INITIALIZER(
  38                                   vmbus_connection.ready_for_resume_event),
  39 };
  40 EXPORT_SYMBOL_GPL(vmbus_connection);
  41
  42 /*
  43  * Negotiated protocol version with the host.
  44  */
  45 __u32 vmbus_proto_version;
  46 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  47
  48 /*
  49  * Table of VMBus versions listed from newest to oldest.
  50  * VERSION_WIN7 and VERSION_WS2008 are no longer supported in
  51  * Linux guests and are not listed.
  52  */
  53 static __u32 vmbus_versions[] = {
  54         VERSION_WIN10_V5_3,
  55         VERSION_WIN10_V5_2,
  56         VERSION_WIN10_V5_1,
  57         VERSION_WIN10_V5,
  58         VERSION_WIN10_V4_1,
  59         VERSION_WIN10,
  60         VERSION_WIN8_1,
  61         VERSION_WIN8
  62 };
  63
  64 /*
  65  * Maximal VMBus protocol version guests can negotiate.  Useful to cap the
  66  * VMBus version for testing and debugging purpose.
  67  */
  68 static uint max_version = VERSION_WIN10_V5_3;
  69
  70 module_param(max_version, uint, S_IRUGO);
  71 MODULE_PARM_DESC(max_version,
  72                  "Maximal VMBus protocol version which can be negotiated");
  73
  74 int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
  75 {
  76         int ret = 0;
  77         struct vmbus_channel_initiate_contact *msg;
  78         unsigned long flags;
  79
  80         init_completion(&msginfo->waitevent);
  81
  82         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  83
  84         memset(msg, 0, sizeof(*msg));
  85         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  86         msg->vmbus_version_requested = version;
  87
  88         /*
  89          * VMBus protocol 5.0 (VERSION_WIN10_V5) and higher require that we must
  90          * use VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
  91          * and for subsequent messages, we must use the Message Connection ID
  92          * field in the host-returned Version Response Message. And, with
  93          * VERSION_WIN10_V5 and higher, we don't use msg->interrupt_page, but we
  94          * tell the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
  95          * compatibility.
  96          *
  97          * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
  98          */
  99         if (version >= VERSION_WIN10_V5) {
 100                 msg->msg_sint = VMBUS_MESSAGE_SINT;
 101                 msg->msg_vtl = ms_hyperv.vtl;
 102                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
 103         } else {
 104                 msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
 105                 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
 106         }
 107
 108         /*
 109          * shared_gpa_boundary is zero in non-SNP VMs, so it's safe to always
 110          * bitwise OR it
 111          */
 112         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]) |
 113                                 ms_hyperv.shared_gpa_boundary;
 114         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]) |
 115                                 ms_hyperv.shared_gpa_boundary;
 116
 117         msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
 118
 119         /*
 120          * Add to list before we send the request since we may
 121          * receive the response before returning from this routine
 122          */
 123         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 124         list_add_tail(&msginfo->msglistentry,
 125                       &vmbus_connection.chn_msg_list);
 126
 127         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 128
 129         ret = vmbus_post_msg(msg,
 130                              sizeof(struct vmbus_channel_initiate_contact),
 131                              true);
 132
 133         trace_vmbus_negotiate_version(msg, ret);
 134
 135         if (ret != 0) {
 136                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 137                 list_del(&msginfo->msglistentry);
 138                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 139                                         flags);
 140                 return ret;
 141         }
 142
 143         /* Wait for the connection response */
 144         wait_for_completion(&msginfo->waitevent);
 145
 146         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 147         list_del(&msginfo->msglistentry);
 148         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 149
 150         /* Check if successful */
 151         if (msginfo->response.version_response.version_supported) {
 152                 vmbus_connection.conn_state = CONNECTED;
 153
 154                 if (version >= VERSION_WIN10_V5)
 155                         vmbus_connection.msg_conn_id =
 156                                 msginfo->response.version_response.msg_conn_id;
 157         } else {
 158                 return -ECONNREFUSED;
 159         }
 160
 161         return ret;
 162 }
 163
 164 /*
 165  * vmbus_connect - Sends a connect request on the partition service connection
 166  */
 167 int vmbus_connect(void)
 168 {
 169         struct vmbus_channel_msginfo *msginfo = NULL;
 170         int i, ret = 0;
 171         __u32 version;
 172
 173         /* Initialize the vmbus connection */
 174         vmbus_connection.conn_state = CONNECTING;
 175         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 176         if (!vmbus_connection.work_queue) {
 177                 ret = -ENOMEM;
 178                 goto cleanup;
 179         }
 180
 181         vmbus_connection.rescind_work_queue =
 182                 create_workqueue("hv_vmbus_rescind");
 183         if (!vmbus_connection.rescind_work_queue) {
 184                 ret = -ENOMEM;
 185                 goto cleanup;
 186         }
 187         vmbus_connection.ignore_any_offer_msg = false;
 188
 189         vmbus_connection.handle_primary_chan_wq =
 190                 create_workqueue("hv_pri_chan");
 191         if (!vmbus_connection.handle_primary_chan_wq) {
 192                 ret = -ENOMEM;
 193                 goto cleanup;
 194         }
 195
 196         vmbus_connection.handle_sub_chan_wq =
 197                 create_workqueue("hv_sub_chan");
 198         if (!vmbus_connection.handle_sub_chan_wq) {
 199                 ret = -ENOMEM;
 200                 goto cleanup;
 201         }
 202
 203         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 204         spin_lock_init(&vmbus_connection.channelmsg_lock);
 205
 206         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 207         mutex_init(&vmbus_connection.channel_mutex);
 208
 209         /*
 210          * Setup the vmbus event connection for channel interrupt
 211          * abstraction stuff
 212          */
 213         vmbus_connection.int_page = hv_alloc_hyperv_zeroed_page();
 214         if (vmbus_connection.int_page == NULL) {
 215                 ret = -ENOMEM;
 216                 goto cleanup;
 217         }
 218
 219         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 220         vmbus_connection.send_int_page =
 221                 (void *)((unsigned long)vmbus_connection.int_page +
 222                         (HV_HYP_PAGE_SIZE >> 1));
 223
 224         /*
 225          * Setup the monitor notification facility. The 1st page for
 226          * parent->child and the 2nd page for child->parent
 227          */
 228         vmbus_connection.monitor_pages[0] = hv_alloc_hyperv_page();
 229         vmbus_connection.monitor_pages[1] = hv_alloc_hyperv_page();
 230         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 231             (vmbus_connection.monitor_pages[1] == NULL)) {
 232                 ret = -ENOMEM;
 233                 goto cleanup;
 234         }
 235
 236         ret = set_memory_decrypted((unsigned long)
 237                                 vmbus_connection.monitor_pages[0], 1);
 238         ret |= set_memory_decrypted((unsigned long)
 239                                 vmbus_connection.monitor_pages[1], 1);
 240         if (ret) {
 241                 /*
 242                  * If set_memory_decrypted() fails, the encryption state
 243                  * of the memory is unknown. So leak the memory instead
 244                  * of risking returning decrypted memory to the free list.
 245                  * For simplicity, always handle both pages the same.
 246                  */
 247                 vmbus_connection.monitor_pages[0] = NULL;
 248                 vmbus_connection.monitor_pages[1] = NULL;
 249                 goto cleanup;
 250         }
 251
 252         /*
 253          * Set_memory_decrypted() will change the memory contents if
 254          * decryption occurs, so zero monitor pages here.
 255          */
 256         memset(vmbus_connection.monitor_pages[0], 0x00, HV_HYP_PAGE_SIZE);
 257         memset(vmbus_connection.monitor_pages[1], 0x00, HV_HYP_PAGE_SIZE);
 258
 259         msginfo = kzalloc(sizeof(*msginfo) +
 260                           sizeof(struct vmbus_channel_initiate_contact),
 261                           GFP_KERNEL);
 262         if (msginfo == NULL) {
 263                 ret = -ENOMEM;
 264                 goto cleanup;
 265         }
 266
 267         /*
 268          * Negotiate a compatible VMBUS version number with the
 269          * host. We start with the highest number we can support
 270          * and work our way down until we negotiate a compatible
 271          * version.
 272          */
 273
 274         for (i = 0; ; i++) {
 275                 if (i == ARRAY_SIZE(vmbus_versions)) {
 276                         ret = -EDOM;
 277                         goto cleanup;
 278                 }
 279
 280                 version = vmbus_versions[i];
 281                 if (version > max_version)
 282                         continue;
 283
 284                 ret = vmbus_negotiate_version(msginfo, version);
 285                 if (ret == -ETIMEDOUT)
 286                         goto cleanup;
 287
 288                 if (vmbus_connection.conn_state == CONNECTED)
 289                         break;
 290         }
 291
 292         if (hv_is_isolation_supported() && version < VERSION_WIN10_V5_2) {
 293                 pr_err("Invalid VMBus version %d.%d (expected >= %d.%d) from the host supporting isolation\n",
 294                        version >> 16, version & 0xFFFF, VERSION_WIN10_V5_2 >> 16, VERSION_WIN10_V5_2 & 0xFFFF);
 295                 ret = -EINVAL;
 296                 goto cleanup;
 297         }
 298
 299         vmbus_proto_version = version;
 300         pr_info("Vmbus version:%d.%d\n",
 301                 version >> 16, version & 0xFFFF);
 302
 303         vmbus_connection.channels = kcalloc(MAX_CHANNEL_RELIDS,
 304                                             sizeof(struct vmbus_channel *),
 305                                             GFP_KERNEL);
 306         if (vmbus_connection.channels == NULL) {
 307                 ret = -ENOMEM;
 308                 goto cleanup;
 309         }
 310
 311         kfree(msginfo);
 312         return 0;
 313
 314 cleanup:
 315         pr_err("Unable to connect to host\n");
 316
 317         vmbus_connection.conn_state = DISCONNECTED;
 318         vmbus_disconnect();
 319
 320         kfree(msginfo);
 321
 322         return ret;
 323 }
 324
 325 void vmbus_disconnect(void)
 326 {
 327         /*
 328          * First send the unload request to the host.
 329          */
 330         vmbus_initiate_unload(false);
 331
 332         if (vmbus_connection.handle_sub_chan_wq)
 333                 destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
 334
 335         if (vmbus_connection.handle_primary_chan_wq)
 336                 destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
 337
 338         if (vmbus_connection.rescind_work_queue)
 339                 destroy_workqueue(vmbus_connection.rescind_work_queue);
 340
 341         if (vmbus_connection.work_queue)
 342                 destroy_workqueue(vmbus_connection.work_queue);
 343
 344         if (vmbus_connection.int_page) {
 345                 hv_free_hyperv_page(vmbus_connection.int_page);
 346                 vmbus_connection.int_page = NULL;
 347         }
 348
 349         if (vmbus_connection.monitor_pages[0]) {
 350                 if (!set_memory_encrypted(
 351                         (unsigned long)vmbus_connection.monitor_pages[0], 1))
 352                         hv_free_hyperv_page(vmbus_connection.monitor_pages[0]);
 353                 vmbus_connection.monitor_pages[0] = NULL;
 354         }
 355
 356         if (vmbus_connection.monitor_pages[1]) {
 357                 if (!set_memory_encrypted(
 358                         (unsigned long)vmbus_connection.monitor_pages[1], 1))
 359                         hv_free_hyperv_page(vmbus_connection.monitor_pages[1]);
 360                 vmbus_connection.monitor_pages[1] = NULL;
 361         }
 362 }
 363
 364 /*
 365  * relid2channel - Get the channel object given its
 366  * child relative id (ie channel id)
 367  */
 368 struct vmbus_channel *relid2channel(u32 relid)
 369 {
 370         if (vmbus_connection.channels == NULL) {
 371                 pr_warn_once("relid2channel: relid=%d: No channels mapped!\n", relid);
 372                 return NULL;
 373         }
 374         if (WARN_ON(relid >= MAX_CHANNEL_RELIDS))
 375                 return NULL;
 376         return READ_ONCE(vmbus_connection.channels[relid]);
 377 }
 378
 379 /*
 380  * vmbus_on_event - Process a channel event notification
 381  *
 382  * For batched channels (default) optimize host to guest signaling
 383  * by ensuring:
 384  * 1. While reading the channel, we disable interrupts from host.
 385  * 2. Ensure that we process all posted messages from the host
 386  *    before returning from this callback.
 387  * 3. Once we return, enable signaling from the host. Once this
 388  *    state is set we check to see if additional packets are
 389  *    available to read. In this case we repeat the process.
 390  *    If this tasklet has been running for a long time
 391  *    then reschedule ourselves.
 392  */
 393 void vmbus_on_event(unsigned long data)
 394 {
 395         struct vmbus_channel *channel = (void *) data;
 396         void (*callback_fn)(void *context);
 397
 398         trace_vmbus_on_event(channel);
 399
 400         hv_debug_delay_test(channel, INTERRUPT_DELAY);
 401
 402         /* A channel once created is persistent even when
 403          * there is no driver handling the device. An
 404          * unloading driver sets the onchannel_callback to NULL.
 405          */
 406         callback_fn = READ_ONCE(channel->onchannel_callback);
 407         if (unlikely(!callback_fn))
 408                 return;
 409
 410         (*callback_fn)(channel->channel_callback_context);
 411
 412         if (channel->callback_mode != HV_CALL_BATCHED)
 413                 return;
 414
 415         if (likely(hv_end_read(&channel->inbound) == 0))
 416                 return;
 417
 418         hv_begin_read(&channel->inbound);
 419         tasklet_schedule(&channel->callback_event);
 420 }
 421
 422 /*
 423  * vmbus_post_msg - Send a msg on the vmbus's message connection
 424  */
 425 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 426 {
 427         struct vmbus_channel_message_header *hdr;
 428         union hv_connection_id conn_id;
 429         int ret = 0;
 430         int retries = 0;
 431         u32 usec = 1;
 432
 433         conn_id.asu32 = 0;
 434         conn_id.u.id = vmbus_connection.msg_conn_id;
 435
 436         /*
 437          * hv_post_message() can have transient failures because of
 438          * insufficient resources. Retry the operation a couple of
 439          * times before giving up.
 440          */
 441         while (retries < 100) {
 442                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 443
 444                 switch (ret) {
 445                 case HV_STATUS_INVALID_CONNECTION_ID:
 446                         /*
 447                          * See vmbus_negotiate_version(): VMBus protocol 5.0
 448                          * and higher require that we must use
 449                          * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
 450                          * Contact message, but on old hosts that only
 451                          * support VMBus protocol 4.0 or lower, here we get
 452                          * HV_STATUS_INVALID_CONNECTION_ID and we should
 453                          * return an error immediately without retrying.
 454                          */
 455                         hdr = buffer;
 456                         if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
 457                                 return -EINVAL;
 458                         /*
 459                          * We could get this if we send messages too
 460                          * frequently.
 461                          */
 462                         ret = -EAGAIN;
 463                         break;
 464                 case HV_STATUS_INSUFFICIENT_MEMORY:
 465                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 466                         ret = -ENOBUFS;
 467                         break;
 468                 case HV_STATUS_SUCCESS:
 469                         return ret;
 470                 default:
 471                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 472                         return -EINVAL;
 473                 }
 474
 475                 retries++;
 476                 if (can_sleep && usec > 1000)
 477                         msleep(usec / 1000);
 478                 else if (usec < MAX_UDELAY_MS * 1000)
 479                         udelay(usec);
 480                 else
 481                         mdelay(usec / 1000);
 482
 483                 if (retries < 22)
 484                         usec *= 2;
 485         }
 486         return ret;
 487 }
 488
 489 /*
 490  * vmbus_set_event - Send an event notification to the parent
 491  */
 492 void vmbus_set_event(struct vmbus_channel *channel)
 493 {
 494         u32 child_relid = channel->offermsg.child_relid;
 495
 496         if (!channel->is_dedicated_interrupt)
 497                 vmbus_send_interrupt(child_relid);
 498
 499         ++channel->sig_events;
 500
 501         if (ms_hyperv.paravisor_present) {
 502                 if (hv_isolation_type_snp())
 503                         hv_ghcb_hypercall(HVCALL_SIGNAL_EVENT, &channel->sig_event,
 504                                           NULL, sizeof(channel->sig_event));
 505                 else if (hv_isolation_type_tdx())
 506                         hv_tdx_hypercall(HVCALL_SIGNAL_EVENT | HV_HYPERCALL_FAST_BIT,
 507                                          channel->sig_event, 0);
 508                 else
 509                         WARN_ON_ONCE(1);
 510         } else {
 511                 hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 512         }
 513 }
 514 EXPORT_SYMBOL_GPL(vmbus_set_event);