drivers/hv/connection.c

   1 /*
   2  *
   3  * Copyright (c) 2009, Microsoft Corporation.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  16  * Place - Suite 330, Boston, MA 02111-1307 USA.
  17  *
  18  * Authors:
  19  *   Haiyang Zhang <haiyangz@microsoft.com>
  20  *   Hank Janssen  <hjanssen@microsoft.com>
  21  *
  22  */
  23 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  24
  25 #include <linux/kernel.h>
  26 #include <linux/sched.h>
  27 #include <linux/wait.h>
  28 #include <linux/delay.h>
  29 #include <linux/mm.h>
  30 #include <linux/slab.h>
  31 #include <linux/vmalloc.h>
  32 #include <linux/hyperv.h>
  33 #include <linux/export.h>
  34 #include <asm/hyperv.h>
  35 #include "hyperv_vmbus.h"
  36
  37
  38 struct vmbus_connection vmbus_connection = {
  39         .conn_state             = DISCONNECTED,
  40         .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),
  41 };
  42 EXPORT_SYMBOL_GPL(vmbus_connection);
  43
  44 /*
  45  * Negotiated protocol version with the host.
  46  */
  47 __u32 vmbus_proto_version;
  48 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  49
  50 static __u32 vmbus_get_next_version(__u32 current_version)
  51 {
  52         switch (current_version) {
  53         case (VERSION_WIN7):
  54                 return VERSION_WS2008;
  55
  56         case (VERSION_WIN8):
  57                 return VERSION_WIN7;
  58
  59         case (VERSION_WIN8_1):
  60                 return VERSION_WIN8;
  61
  62         case (VERSION_WIN10):
  63                 return VERSION_WIN8_1;
  64
  65         case (VERSION_WS2008):
  66         default:
  67                 return VERSION_INVAL;
  68         }
  69 }
  70
  71 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  72                                         __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         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  83         msg->vmbus_version_requested = version;
  84         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  85         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
  86         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
  87         /*
  88          * We want all channel messages to be delivered on CPU 0.
  89          * This has been the behavior pre-win8. This is not
  90          * perf issue and having all channel messages delivered on CPU 0
  91          * would be ok.
  92          * For post win8 hosts, we support receiving channel messagges on
  93          * all the CPUs. This is needed for kexec to work correctly where
  94          * the CPU attempting to connect may not be CPU 0.
  95          */
  96         if (version >= VERSION_WIN8_1) {
  97                 msg->target_vcpu = hv_context.vp_index[get_cpu()];
  98                 put_cpu();
  99         } else {
 100                 msg->target_vcpu = 0;
 101         }
 102
 103         /*
 104          * Add to list before we send the request since we may
 105          * receive the response before returning from this routine
 106          */
 107         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 108         list_add_tail(&msginfo->msglistentry,
 109                       &vmbus_connection.chn_msg_list);
 110
 111         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 112
 113         ret = vmbus_post_msg(msg,
 114                                sizeof(struct vmbus_channel_initiate_contact));
 115         if (ret != 0) {
 116                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 117                 list_del(&msginfo->msglistentry);
 118                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 119                                         flags);
 120                 return ret;
 121         }
 122
 123         /* Wait for the connection response */
 124         wait_for_completion(&msginfo->waitevent);
 125
 126         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 127         list_del(&msginfo->msglistentry);
 128         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 129
 130         /* Check if successful */
 131         if (msginfo->response.version_response.version_supported) {
 132                 vmbus_connection.conn_state = CONNECTED;
 133         } else {
 134                 return -ECONNREFUSED;
 135         }
 136
 137         return ret;
 138 }
 139
 140 /*
 141  * vmbus_connect - Sends a connect request on the partition service connection
 142  */
 143 int vmbus_connect(void)
 144 {
 145         int ret = 0;
 146         struct vmbus_channel_msginfo *msginfo = NULL;
 147         __u32 version;
 148
 149         /* Initialize the vmbus connection */
 150         vmbus_connection.conn_state = CONNECTING;
 151         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 152         if (!vmbus_connection.work_queue) {
 153                 ret = -ENOMEM;
 154                 goto cleanup;
 155         }
 156
 157         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 158         spin_lock_init(&vmbus_connection.channelmsg_lock);
 159
 160         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 161         mutex_init(&vmbus_connection.channel_mutex);
 162
 163         /*
 164          * Setup the vmbus event connection for channel interrupt
 165          * abstraction stuff
 166          */
 167         vmbus_connection.int_page =
 168         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 169         if (vmbus_connection.int_page == NULL) {
 170                 ret = -ENOMEM;
 171                 goto cleanup;
 172         }
 173
 174         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 175         vmbus_connection.send_int_page =
 176                 (void *)((unsigned long)vmbus_connection.int_page +
 177                         (PAGE_SIZE >> 1));
 178
 179         /*
 180          * Setup the monitor notification facility. The 1st page for
 181          * parent->child and the 2nd page for child->parent
 182          */
 183         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 184         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 185         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 186             (vmbus_connection.monitor_pages[1] == NULL)) {
 187                 ret = -ENOMEM;
 188                 goto cleanup;
 189         }
 190
 191         msginfo = kzalloc(sizeof(*msginfo) +
 192                           sizeof(struct vmbus_channel_initiate_contact),
 193                           GFP_KERNEL);
 194         if (msginfo == NULL) {
 195                 ret = -ENOMEM;
 196                 goto cleanup;
 197         }
 198
 199         /*
 200          * Negotiate a compatible VMBUS version number with the
 201          * host. We start with the highest number we can support
 202          * and work our way down until we negotiate a compatible
 203          * version.
 204          */
 205
 206         version = VERSION_CURRENT;
 207
 208         do {
 209                 ret = vmbus_negotiate_version(msginfo, version);
 210                 if (ret == -ETIMEDOUT)
 211                         goto cleanup;
 212
 213                 if (vmbus_connection.conn_state == CONNECTED)
 214                         break;
 215
 216                 version = vmbus_get_next_version(version);
 217         } while (version != VERSION_INVAL);
 218
 219         if (version == VERSION_INVAL)
 220                 goto cleanup;
 221
 222         vmbus_proto_version = version;
 223         pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
 224                     host_info_eax, host_info_ebx >> 16,
 225                     host_info_ebx & 0xFFFF, host_info_ecx,
 226                     host_info_edx >> 24, host_info_edx & 0xFFFFFF,
 227                     version >> 16, version & 0xFFFF);
 228
 229         kfree(msginfo);
 230         return 0;
 231
 232 cleanup:
 233         pr_err("Unable to connect to host\n");
 234
 235         vmbus_connection.conn_state = DISCONNECTED;
 236         vmbus_disconnect();
 237
 238         kfree(msginfo);
 239
 240         return ret;
 241 }
 242
 243 void vmbus_disconnect(void)
 244 {
 245         /*
 246          * First send the unload request to the host.
 247          */
 248         vmbus_initiate_unload(false);
 249
 250         if (vmbus_connection.work_queue) {
 251                 drain_workqueue(vmbus_connection.work_queue);
 252                 destroy_workqueue(vmbus_connection.work_queue);
 253         }
 254
 255         if (vmbus_connection.int_page) {
 256                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 257                 vmbus_connection.int_page = NULL;
 258         }
 259
 260         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 261         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 262         vmbus_connection.monitor_pages[0] = NULL;
 263         vmbus_connection.monitor_pages[1] = NULL;
 264 }
 265
 266 /*
 267  * Map the given relid to the corresponding channel based on the
 268  * per-cpu list of channels that have been affinitized to this CPU.
 269  * This will be used in the channel callback path as we can do this
 270  * mapping in a lock-free fashion.
 271  */
 272 static struct vmbus_channel *pcpu_relid2channel(u32 relid)
 273 {
 274         struct vmbus_channel *channel;
 275         struct vmbus_channel *found_channel  = NULL;
 276         int cpu = smp_processor_id();
 277         struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
 278
 279         list_for_each_entry(channel, pcpu_head, percpu_list) {
 280                 if (channel->offermsg.child_relid == relid) {
 281                         found_channel = channel;
 282                         break;
 283                 }
 284         }
 285
 286         return found_channel;
 287 }
 288
 289 /*
 290  * relid2channel - Get the channel object given its
 291  * child relative id (ie channel id)
 292  */
 293 struct vmbus_channel *relid2channel(u32 relid)
 294 {
 295         struct vmbus_channel *channel;
 296         struct vmbus_channel *found_channel  = NULL;
 297         struct list_head *cur, *tmp;
 298         struct vmbus_channel *cur_sc;
 299
 300         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 301
 302         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 303                 if (channel->offermsg.child_relid == relid) {
 304                         found_channel = channel;
 305                         break;
 306                 } else if (!list_empty(&channel->sc_list)) {
 307                         /*
 308                          * Deal with sub-channels.
 309                          */
 310                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 311                                 cur_sc = list_entry(cur, struct vmbus_channel,
 312                                                         sc_list);
 313                                 if (cur_sc->offermsg.child_relid == relid) {
 314                                         found_channel = cur_sc;
 315                                         break;
 316                                 }
 317                         }
 318                 }
 319         }
 320
 321         return found_channel;
 322 }
 323
 324 /*
 325  * process_chn_event - Process a channel event notification
 326  */
 327 static void process_chn_event(u32 relid)
 328 {
 329         struct vmbus_channel *channel;
 330         void *arg;
 331         bool read_state;
 332         u32 bytes_to_read;
 333
 334         /*
 335          * Find the channel based on this relid and invokes the
 336          * channel callback to process the event
 337          */
 338         channel = pcpu_relid2channel(relid);
 339
 340         if (!channel)
 341                 return;
 342
 343         /*
 344          * A channel once created is persistent even when there
 345          * is no driver handling the device. An unloading driver
 346          * sets the onchannel_callback to NULL on the same CPU
 347          * as where this interrupt is handled (in an interrupt context).
 348          * Thus, checking and invoking the driver specific callback takes
 349          * care of orderly unloading of the driver.
 350          */
 351
 352         if (channel->onchannel_callback != NULL) {
 353                 arg = channel->channel_callback_context;
 354                 read_state = channel->batched_reading;
 355                 /*
 356                  * This callback reads the messages sent by the host.
 357                  * We can optimize host to guest signaling by ensuring:
 358                  * 1. While reading the channel, we disable interrupts from
 359                  *    host.
 360                  * 2. Ensure that we process all posted messages from the host
 361                  *    before returning from this callback.
 362                  * 3. Once we return, enable signaling from the host. Once this
 363                  *    state is set we check to see if additional packets are
 364                  *    available to read. In this case we repeat the process.
 365                  */
 366
 367                 do {
 368                         if (read_state)
 369                                 hv_begin_read(&channel->inbound);
 370                         channel->onchannel_callback(arg);
 371                         if (read_state)
 372                                 bytes_to_read = hv_end_read(&channel->inbound);
 373                         else
 374                                 bytes_to_read = 0;
 375                 } while (read_state && (bytes_to_read != 0));
 376         }
 377 }
 378
 379 /*
 380  * vmbus_on_event - Handler for events
 381  */
 382 void vmbus_on_event(unsigned long data)
 383 {
 384         u32 dword;
 385         u32 maxdword;
 386         int bit;
 387         u32 relid;
 388         u32 *recv_int_page = NULL;
 389         void *page_addr;
 390         int cpu = smp_processor_id();
 391         union hv_synic_event_flags *event;
 392
 393         if (vmbus_proto_version < VERSION_WIN8) {
 394                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 395                 recv_int_page = vmbus_connection.recv_int_page;
 396         } else {
 397                 /*
 398                  * When the host is win8 and beyond, the event page
 399                  * can be directly checked to get the id of the channel
 400                  * that has the interrupt pending.
 401                  */
 402                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 403                 page_addr = hv_context.synic_event_page[cpu];
 404                 event = (union hv_synic_event_flags *)page_addr +
 405                                                  VMBUS_MESSAGE_SINT;
 406                 recv_int_page = event->flags32;
 407         }
 408
 409
 410
 411         /* Check events */
 412         if (!recv_int_page)
 413                 return;
 414         for (dword = 0; dword < maxdword; dword++) {
 415                 if (!recv_int_page[dword])
 416                         continue;
 417                 for (bit = 0; bit < 32; bit++) {
 418                         if (sync_test_and_clear_bit(bit,
 419                                 (unsigned long *)&recv_int_page[dword])) {
 420                                 relid = (dword << 5) + bit;
 421
 422                                 if (relid == 0)
 423                                         /*
 424                                          * Special case - vmbus
 425                                          * channel protocol msg
 426                                          */
 427                                         continue;
 428
 429                                 process_chn_event(relid);
 430                         }
 431                 }
 432         }
 433 }
 434
 435 /*
 436  * vmbus_post_msg - Send a msg on the vmbus's message connection
 437  */
 438 int vmbus_post_msg(void *buffer, size_t buflen)
 439 {
 440         union hv_connection_id conn_id;
 441         int ret = 0;
 442         int retries = 0;
 443         u32 usec = 1;
 444
 445         conn_id.asu32 = 0;
 446         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 447
 448         /*
 449          * hv_post_message() can have transient failures because of
 450          * insufficient resources. Retry the operation a couple of
 451          * times before giving up.
 452          */
 453         while (retries < 20) {
 454                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 455
 456                 switch (ret) {
 457                 case HV_STATUS_INVALID_CONNECTION_ID:
 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 = -ENOMEM;
 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                 udelay(usec);
 477                 if (usec < 2048)
 478                         usec *= 2;
 479         }
 480         return ret;
 481 }
 482
 483 /*
 484  * vmbus_set_event - Send an event notification to the parent
 485  */
 486 void vmbus_set_event(struct vmbus_channel *channel)
 487 {
 488         u32 child_relid = channel->offermsg.child_relid;
 489
 490         if (!channel->is_dedicated_interrupt) {
 491                 /* Each u32 represents 32 channels */
 492                 sync_set_bit(child_relid & 31,
 493                         (unsigned long *)vmbus_connection.send_int_page +
 494                         (child_relid >> 5));
 495         }
 496
 497         hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
 498 }
 499 EXPORT_SYMBOL_GPL(vmbus_set_event);