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
  43 /*
  44  * Negotiated protocol version with the host.
  45  */
  46 __u32 vmbus_proto_version;
  47 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  48
  49 static __u32 vmbus_get_next_version(__u32 current_version)
  50 {
  51         switch (current_version) {
  52         case (VERSION_WIN7):
  53                 return VERSION_WS2008;
  54
  55         case (VERSION_WIN8):
  56                 return VERSION_WIN7;
  57
  58         case (VERSION_WIN8_1):
  59                 return VERSION_WIN8;
  60
  61         case (VERSION_WIN10):
  62                 return VERSION_WIN8_1;
  63
  64         case (VERSION_WS2008):
  65         default:
  66                 return VERSION_INVAL;
  67         }
  68 }
  69
  70 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  71                                         __u32 version)
  72 {
  73         int ret = 0;
  74         struct vmbus_channel_initiate_contact *msg;
  75         unsigned long flags;
  76
  77         init_completion(&msginfo->waitevent);
  78
  79         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  80
  81         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  82         msg->vmbus_version_requested = version;
  83         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  84         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
  85         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
  86         if (version >= VERSION_WIN8_1) {
  87                 msg->target_vcpu = hv_context.vp_index[get_cpu()];
  88                 put_cpu();
  89         }
  90
  91         /*
  92          * Add to list before we send the request since we may
  93          * receive the response before returning from this routine
  94          */
  95         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
  96         list_add_tail(&msginfo->msglistentry,
  97                       &vmbus_connection.chn_msg_list);
  98
  99         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 100
 101         ret = vmbus_post_msg(msg,
 102                                sizeof(struct vmbus_channel_initiate_contact));
 103         if (ret != 0) {
 104                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 105                 list_del(&msginfo->msglistentry);
 106                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 107                                         flags);
 108                 return ret;
 109         }
 110
 111         /* Wait for the connection response */
 112         wait_for_completion(&msginfo->waitevent);
 113
 114         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 115         list_del(&msginfo->msglistentry);
 116         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 117
 118         /* Check if successful */
 119         if (msginfo->response.version_response.version_supported) {
 120                 vmbus_connection.conn_state = CONNECTED;
 121         } else {
 122                 return -ECONNREFUSED;
 123         }
 124
 125         return ret;
 126 }
 127
 128 /*
 129  * vmbus_connect - Sends a connect request on the partition service connection
 130  */
 131 int vmbus_connect(void)
 132 {
 133         int ret = 0;
 134         struct vmbus_channel_msginfo *msginfo = NULL;
 135         __u32 version;
 136
 137         /* Initialize the vmbus connection */
 138         vmbus_connection.conn_state = CONNECTING;
 139         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 140         if (!vmbus_connection.work_queue) {
 141                 ret = -ENOMEM;
 142                 goto cleanup;
 143         }
 144
 145         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 146         spin_lock_init(&vmbus_connection.channelmsg_lock);
 147
 148         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 149         spin_lock_init(&vmbus_connection.channel_lock);
 150
 151         /*
 152          * Setup the vmbus event connection for channel interrupt
 153          * abstraction stuff
 154          */
 155         vmbus_connection.int_page =
 156         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 157         if (vmbus_connection.int_page == NULL) {
 158                 ret = -ENOMEM;
 159                 goto cleanup;
 160         }
 161
 162         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 163         vmbus_connection.send_int_page =
 164                 (void *)((unsigned long)vmbus_connection.int_page +
 165                         (PAGE_SIZE >> 1));
 166
 167         /*
 168          * Setup the monitor notification facility. The 1st page for
 169          * parent->child and the 2nd page for child->parent
 170          */
 171         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 172         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 173         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 174             (vmbus_connection.monitor_pages[1] == NULL)) {
 175                 ret = -ENOMEM;
 176                 goto cleanup;
 177         }
 178
 179         msginfo = kzalloc(sizeof(*msginfo) +
 180                           sizeof(struct vmbus_channel_initiate_contact),
 181                           GFP_KERNEL);
 182         if (msginfo == NULL) {
 183                 ret = -ENOMEM;
 184                 goto cleanup;
 185         }
 186
 187         /*
 188          * Negotiate a compatible VMBUS version number with the
 189          * host. We start with the highest number we can support
 190          * and work our way down until we negotiate a compatible
 191          * version.
 192          */
 193
 194         version = VERSION_CURRENT;
 195
 196         do {
 197                 ret = vmbus_negotiate_version(msginfo, version);
 198                 if (ret == -ETIMEDOUT)
 199                         goto cleanup;
 200
 201                 if (vmbus_connection.conn_state == CONNECTED)
 202                         break;
 203
 204                 version = vmbus_get_next_version(version);
 205         } while (version != VERSION_INVAL);
 206
 207         if (version == VERSION_INVAL)
 208                 goto cleanup;
 209
 210         vmbus_proto_version = version;
 211         pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
 212                     host_info_eax, host_info_ebx >> 16,
 213                     host_info_ebx & 0xFFFF, host_info_ecx,
 214                     host_info_edx >> 24, host_info_edx & 0xFFFFFF,
 215                     version >> 16, version & 0xFFFF);
 216
 217         kfree(msginfo);
 218         return 0;
 219
 220 cleanup:
 221         pr_err("Unable to connect to host\n");
 222
 223         vmbus_connection.conn_state = DISCONNECTED;
 224         vmbus_disconnect();
 225
 226         kfree(msginfo);
 227
 228         return ret;
 229 }
 230
 231 void vmbus_disconnect(void)
 232 {
 233         /*
 234          * First send the unload request to the host.
 235          */
 236         vmbus_initiate_unload();
 237
 238         if (vmbus_connection.work_queue) {
 239                 drain_workqueue(vmbus_connection.work_queue);
 240                 destroy_workqueue(vmbus_connection.work_queue);
 241         }
 242
 243         if (vmbus_connection.int_page) {
 244                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 245                 vmbus_connection.int_page = NULL;
 246         }
 247
 248         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 249         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 250         vmbus_connection.monitor_pages[0] = NULL;
 251         vmbus_connection.monitor_pages[1] = NULL;
 252 }
 253
 254 /*
 255  * Map the given relid to the corresponding channel based on the
 256  * per-cpu list of channels that have been affinitized to this CPU.
 257  * This will be used in the channel callback path as we can do this
 258  * mapping in a lock-free fashion.
 259  */
 260 static struct vmbus_channel *pcpu_relid2channel(u32 relid)
 261 {
 262         struct vmbus_channel *channel;
 263         struct vmbus_channel *found_channel  = NULL;
 264         int cpu = smp_processor_id();
 265         struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
 266
 267         list_for_each_entry(channel, pcpu_head, percpu_list) {
 268                 if (channel->offermsg.child_relid == relid) {
 269                         found_channel = channel;
 270                         break;
 271                 }
 272         }
 273
 274         return found_channel;
 275 }
 276
 277 /*
 278  * relid2channel - Get the channel object given its
 279  * child relative id (ie channel id)
 280  */
 281 struct vmbus_channel *relid2channel(u32 relid)
 282 {
 283         struct vmbus_channel *channel;
 284         struct vmbus_channel *found_channel  = NULL;
 285         unsigned long flags;
 286         struct list_head *cur, *tmp;
 287         struct vmbus_channel *cur_sc;
 288
 289         spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 290         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 291                 if (channel->offermsg.child_relid == relid) {
 292                         found_channel = channel;
 293                         break;
 294                 } else if (!list_empty(&channel->sc_list)) {
 295                         /*
 296                          * Deal with sub-channels.
 297                          */
 298                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 299                                 cur_sc = list_entry(cur, struct vmbus_channel,
 300                                                         sc_list);
 301                                 if (cur_sc->offermsg.child_relid == relid) {
 302                                         found_channel = cur_sc;
 303                                         break;
 304                                 }
 305                         }
 306                 }
 307         }
 308         spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 309
 310         return found_channel;
 311 }
 312
 313 /*
 314  * process_chn_event - Process a channel event notification
 315  */
 316 static void process_chn_event(u32 relid)
 317 {
 318         struct vmbus_channel *channel;
 319         void *arg;
 320         bool read_state;
 321         u32 bytes_to_read;
 322
 323         /*
 324          * Find the channel based on this relid and invokes the
 325          * channel callback to process the event
 326          */
 327         channel = pcpu_relid2channel(relid);
 328
 329         if (!channel)
 330                 return;
 331
 332         /*
 333          * A channel once created is persistent even when there
 334          * is no driver handling the device. An unloading driver
 335          * sets the onchannel_callback to NULL on the same CPU
 336          * as where this interrupt is handled (in an interrupt context).
 337          * Thus, checking and invoking the driver specific callback takes
 338          * care of orderly unloading of the driver.
 339          */
 340
 341         if (channel->onchannel_callback != NULL) {
 342                 arg = channel->channel_callback_context;
 343                 read_state = channel->batched_reading;
 344                 /*
 345                  * This callback reads the messages sent by the host.
 346                  * We can optimize host to guest signaling by ensuring:
 347                  * 1. While reading the channel, we disable interrupts from
 348                  *    host.
 349                  * 2. Ensure that we process all posted messages from the host
 350                  *    before returning from this callback.
 351                  * 3. Once we return, enable signaling from the host. Once this
 352                  *    state is set we check to see if additional packets are
 353                  *    available to read. In this case we repeat the process.
 354                  */
 355
 356                 do {
 357                         if (read_state)
 358                                 hv_begin_read(&channel->inbound);
 359                         channel->onchannel_callback(arg);
 360                         if (read_state)
 361                                 bytes_to_read = hv_end_read(&channel->inbound);
 362                         else
 363                                 bytes_to_read = 0;
 364                 } while (read_state && (bytes_to_read != 0));
 365         }
 366 }
 367
 368 /*
 369  * vmbus_on_event - Handler for events
 370  */
 371 void vmbus_on_event(unsigned long data)
 372 {
 373         u32 dword;
 374         u32 maxdword;
 375         int bit;
 376         u32 relid;
 377         u32 *recv_int_page = NULL;
 378         void *page_addr;
 379         int cpu = smp_processor_id();
 380         union hv_synic_event_flags *event;
 381
 382         if (vmbus_proto_version < VERSION_WIN8) {
 383                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 384                 recv_int_page = vmbus_connection.recv_int_page;
 385         } else {
 386                 /*
 387                  * When the host is win8 and beyond, the event page
 388                  * can be directly checked to get the id of the channel
 389                  * that has the interrupt pending.
 390                  */
 391                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 392                 page_addr = hv_context.synic_event_page[cpu];
 393                 event = (union hv_synic_event_flags *)page_addr +
 394                                                  VMBUS_MESSAGE_SINT;
 395                 recv_int_page = event->flags32;
 396         }
 397
 398
 399
 400         /* Check events */
 401         if (!recv_int_page)
 402                 return;
 403         for (dword = 0; dword < maxdword; dword++) {
 404                 if (!recv_int_page[dword])
 405                         continue;
 406                 for (bit = 0; bit < 32; bit++) {
 407                         if (sync_test_and_clear_bit(bit,
 408                                 (unsigned long *)&recv_int_page[dword])) {
 409                                 relid = (dword << 5) + bit;
 410
 411                                 if (relid == 0)
 412                                         /*
 413                                          * Special case - vmbus
 414                                          * channel protocol msg
 415                                          */
 416                                         continue;
 417
 418                                 process_chn_event(relid);
 419                         }
 420                 }
 421         }
 422 }
 423
 424 /*
 425  * vmbus_post_msg - Send a msg on the vmbus's message connection
 426  */
 427 int vmbus_post_msg(void *buffer, size_t buflen)
 428 {
 429         union hv_connection_id conn_id;
 430         int ret = 0;
 431         int retries = 0;
 432         u32 usec = 1;
 433
 434         conn_id.asu32 = 0;
 435         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 436
 437         /*
 438          * hv_post_message() can have transient failures because of
 439          * insufficient resources. Retry the operation a couple of
 440          * times before giving up.
 441          */
 442         while (retries < 20) {
 443                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 444
 445                 switch (ret) {
 446                 case HV_STATUS_INVALID_CONNECTION_ID:
 447                         /*
 448                          * We could get this if we send messages too
 449                          * frequently.
 450                          */
 451                         ret = -EAGAIN;
 452                         break;
 453                 case HV_STATUS_INSUFFICIENT_MEMORY:
 454                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 455                         ret = -ENOMEM;
 456                         break;
 457                 case HV_STATUS_SUCCESS:
 458                         return ret;
 459                 default:
 460                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 461                         return -EINVAL;
 462                 }
 463
 464                 retries++;
 465                 udelay(usec);
 466                 if (usec < 2048)
 467                         usec *= 2;
 468         }
 469         return ret;
 470 }
 471
 472 /*
 473  * vmbus_set_event - Send an event notification to the parent
 474  */
 475 int vmbus_set_event(struct vmbus_channel *channel)
 476 {
 477         u32 child_relid = channel->offermsg.child_relid;
 478
 479         if (!channel->is_dedicated_interrupt) {
 480                 /* Each u32 represents 32 channels */
 481                 sync_set_bit(child_relid & 31,
 482                         (unsigned long *)vmbus_connection.send_int_page +
 483                         (child_relid >> 5));
 484         }
 485
 486         return hv_signal_event(channel->sig_event);
 487 }