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_WS2008):
  62         default:
  63                 return VERSION_INVAL;
  64         }
  65 }
  66
  67 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  68                                         __u32 version)
  69 {
  70         int ret = 0;
  71         struct vmbus_channel_initiate_contact *msg;
  72         unsigned long flags;
  73
  74         init_completion(&msginfo->waitevent);
  75
  76         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  77
  78         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  79         msg->vmbus_version_requested = version;
  80         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  81         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
  82         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
  83         if (version == VERSION_WIN8_1)
  84                 msg->target_vcpu = hv_context.vp_index[smp_processor_id()];
  85
  86         /*
  87          * Add to list before we send the request since we may
  88          * receive the response before returning from this routine
  89          */
  90         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
  91         list_add_tail(&msginfo->msglistentry,
  92                       &vmbus_connection.chn_msg_list);
  93
  94         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
  95
  96         ret = vmbus_post_msg(msg,
  97                                sizeof(struct vmbus_channel_initiate_contact));
  98         if (ret != 0) {
  99                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 100                 list_del(&msginfo->msglistentry);
 101                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 102                                         flags);
 103                 return ret;
 104         }
 105
 106         /* Wait for the connection response */
 107         wait_for_completion(&msginfo->waitevent);
 108
 109         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 110         list_del(&msginfo->msglistentry);
 111         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 112
 113         /* Check if successful */
 114         if (msginfo->response.version_response.version_supported) {
 115                 vmbus_connection.conn_state = CONNECTED;
 116         } else {
 117                 return -ECONNREFUSED;
 118         }
 119
 120         return ret;
 121 }
 122
 123 /*
 124  * vmbus_connect - Sends a connect request on the partition service connection
 125  */
 126 int vmbus_connect(void)
 127 {
 128         int ret = 0;
 129         struct vmbus_channel_msginfo *msginfo = NULL;
 130         __u32 version;
 131
 132         /* Initialize the vmbus connection */
 133         vmbus_connection.conn_state = CONNECTING;
 134         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 135         if (!vmbus_connection.work_queue) {
 136                 ret = -ENOMEM;
 137                 goto cleanup;
 138         }
 139
 140         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 141         spin_lock_init(&vmbus_connection.channelmsg_lock);
 142
 143         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 144         spin_lock_init(&vmbus_connection.channel_lock);
 145
 146         /*
 147          * Setup the vmbus event connection for channel interrupt
 148          * abstraction stuff
 149          */
 150         vmbus_connection.int_page =
 151         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 152         if (vmbus_connection.int_page == NULL) {
 153                 ret = -ENOMEM;
 154                 goto cleanup;
 155         }
 156
 157         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 158         vmbus_connection.send_int_page =
 159                 (void *)((unsigned long)vmbus_connection.int_page +
 160                         (PAGE_SIZE >> 1));
 161
 162         /*
 163          * Setup the monitor notification facility. The 1st page for
 164          * parent->child and the 2nd page for child->parent
 165          */
 166         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 167         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 168         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 169             (vmbus_connection.monitor_pages[1] == NULL)) {
 170                 ret = -ENOMEM;
 171                 goto cleanup;
 172         }
 173
 174         msginfo = kzalloc(sizeof(*msginfo) +
 175                           sizeof(struct vmbus_channel_initiate_contact),
 176                           GFP_KERNEL);
 177         if (msginfo == NULL) {
 178                 ret = -ENOMEM;
 179                 goto cleanup;
 180         }
 181
 182         /*
 183          * Negotiate a compatible VMBUS version number with the
 184          * host. We start with the highest number we can support
 185          * and work our way down until we negotiate a compatible
 186          * version.
 187          */
 188
 189         version = VERSION_CURRENT;
 190
 191         do {
 192                 ret = vmbus_negotiate_version(msginfo, version);
 193                 if (ret == -ETIMEDOUT)
 194                         goto cleanup;
 195
 196                 if (vmbus_connection.conn_state == CONNECTED)
 197                         break;
 198
 199                 version = vmbus_get_next_version(version);
 200         } while (version != VERSION_INVAL);
 201
 202         if (version == VERSION_INVAL)
 203                 goto cleanup;
 204
 205         vmbus_proto_version = version;
 206         pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
 207                     host_info_eax, host_info_ebx >> 16,
 208                     host_info_ebx & 0xFFFF, host_info_ecx,
 209                     host_info_edx >> 24, host_info_edx & 0xFFFFFF,
 210                     version >> 16, version & 0xFFFF);
 211
 212         kfree(msginfo);
 213         return 0;
 214
 215 cleanup:
 216         pr_err("Unable to connect to host\n");
 217         vmbus_connection.conn_state = DISCONNECTED;
 218
 219         if (vmbus_connection.work_queue)
 220                 destroy_workqueue(vmbus_connection.work_queue);
 221
 222         if (vmbus_connection.int_page) {
 223                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 224                 vmbus_connection.int_page = NULL;
 225         }
 226
 227         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 228         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 229         vmbus_connection.monitor_pages[0] = NULL;
 230         vmbus_connection.monitor_pages[1] = NULL;
 231
 232         kfree(msginfo);
 233
 234         return ret;
 235 }
 236
 237 /*
 238  * Map the given relid to the corresponding channel based on the
 239  * per-cpu list of channels that have been affinitized to this CPU.
 240  * This will be used in the channel callback path as we can do this
 241  * mapping in a lock-free fashion.
 242  */
 243 static struct vmbus_channel *pcpu_relid2channel(u32 relid)
 244 {
 245         struct vmbus_channel *channel;
 246         struct vmbus_channel *found_channel  = NULL;
 247         int cpu = smp_processor_id();
 248         struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
 249
 250         list_for_each_entry(channel, pcpu_head, percpu_list) {
 251                 if (channel->offermsg.child_relid == relid) {
 252                         found_channel = channel;
 253                         break;
 254                 }
 255         }
 256
 257         return found_channel;
 258 }
 259
 260 /*
 261  * relid2channel - Get the channel object given its
 262  * child relative id (ie channel id)
 263  */
 264 struct vmbus_channel *relid2channel(u32 relid)
 265 {
 266         struct vmbus_channel *channel;
 267         struct vmbus_channel *found_channel  = NULL;
 268         unsigned long flags;
 269         struct list_head *cur, *tmp;
 270         struct vmbus_channel *cur_sc;
 271
 272         spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 273         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 274                 if (channel->offermsg.child_relid == relid) {
 275                         found_channel = channel;
 276                         break;
 277                 } else if (!list_empty(&channel->sc_list)) {
 278                         /*
 279                          * Deal with sub-channels.
 280                          */
 281                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 282                                 cur_sc = list_entry(cur, struct vmbus_channel,
 283                                                         sc_list);
 284                                 if (cur_sc->offermsg.child_relid == relid) {
 285                                         found_channel = cur_sc;
 286                                         break;
 287                                 }
 288                         }
 289                 }
 290         }
 291         spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 292
 293         return found_channel;
 294 }
 295
 296 /*
 297  * process_chn_event - Process a channel event notification
 298  */
 299 static void process_chn_event(u32 relid)
 300 {
 301         struct vmbus_channel *channel;
 302         void *arg;
 303         bool read_state;
 304         u32 bytes_to_read;
 305
 306         /*
 307          * Find the channel based on this relid and invokes the
 308          * channel callback to process the event
 309          */
 310         channel = pcpu_relid2channel(relid);
 311
 312         if (!channel) {
 313                 pr_err("channel not found for relid - %u\n", relid);
 314                 return;
 315         }
 316
 317         /*
 318          * A channel once created is persistent even when there
 319          * is no driver handling the device. An unloading driver
 320          * sets the onchannel_callback to NULL on the same CPU
 321          * as where this interrupt is handled (in an interrupt context).
 322          * Thus, checking and invoking the driver specific callback takes
 323          * care of orderly unloading of the driver.
 324          */
 325
 326         if (channel->onchannel_callback != NULL) {
 327                 arg = channel->channel_callback_context;
 328                 read_state = channel->batched_reading;
 329                 /*
 330                  * This callback reads the messages sent by the host.
 331                  * We can optimize host to guest signaling by ensuring:
 332                  * 1. While reading the channel, we disable interrupts from
 333                  *    host.
 334                  * 2. Ensure that we process all posted messages from the host
 335                  *    before returning from this callback.
 336                  * 3. Once we return, enable signaling from the host. Once this
 337                  *    state is set we check to see if additional packets are
 338                  *    available to read. In this case we repeat the process.
 339                  */
 340
 341                 do {
 342                         if (read_state)
 343                                 hv_begin_read(&channel->inbound);
 344                         channel->onchannel_callback(arg);
 345                         if (read_state)
 346                                 bytes_to_read = hv_end_read(&channel->inbound);
 347                         else
 348                                 bytes_to_read = 0;
 349                 } while (read_state && (bytes_to_read != 0));
 350         } else {
 351                 pr_err("no channel callback for relid - %u\n", relid);
 352         }
 353
 354 }
 355
 356 /*
 357  * vmbus_on_event - Handler for events
 358  */
 359 void vmbus_on_event(unsigned long data)
 360 {
 361         u32 dword;
 362         u32 maxdword;
 363         int bit;
 364         u32 relid;
 365         u32 *recv_int_page = NULL;
 366         void *page_addr;
 367         int cpu = smp_processor_id();
 368         union hv_synic_event_flags *event;
 369
 370         if ((vmbus_proto_version == VERSION_WS2008) ||
 371                 (vmbus_proto_version == VERSION_WIN7)) {
 372                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 373                 recv_int_page = vmbus_connection.recv_int_page;
 374         } else {
 375                 /*
 376                  * When the host is win8 and beyond, the event page
 377                  * can be directly checked to get the id of the channel
 378                  * that has the interrupt pending.
 379                  */
 380                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 381                 page_addr = hv_context.synic_event_page[cpu];
 382                 event = (union hv_synic_event_flags *)page_addr +
 383                                                  VMBUS_MESSAGE_SINT;
 384                 recv_int_page = event->flags32;
 385         }
 386
 387
 388
 389         /* Check events */
 390         if (!recv_int_page)
 391                 return;
 392         for (dword = 0; dword < maxdword; dword++) {
 393                 if (!recv_int_page[dword])
 394                         continue;
 395                 for (bit = 0; bit < 32; bit++) {
 396                         if (sync_test_and_clear_bit(bit,
 397                                 (unsigned long *)&recv_int_page[dword])) {
 398                                 relid = (dword << 5) + bit;
 399
 400                                 if (relid == 0)
 401                                         /*
 402                                          * Special case - vmbus
 403                                          * channel protocol msg
 404                                          */
 405                                         continue;
 406
 407                                 process_chn_event(relid);
 408                         }
 409                 }
 410         }
 411 }
 412
 413 /*
 414  * vmbus_post_msg - Send a msg on the vmbus's message connection
 415  */
 416 int vmbus_post_msg(void *buffer, size_t buflen)
 417 {
 418         union hv_connection_id conn_id;
 419         int ret = 0;
 420         int retries = 0;
 421
 422         conn_id.asu32 = 0;
 423         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 424
 425         /*
 426          * hv_post_message() can have transient failures because of
 427          * insufficient resources. Retry the operation a couple of
 428          * times before giving up.
 429          */
 430         while (retries < 3) {
 431                 ret =  hv_post_message(conn_id, 1, buffer, buflen);
 432                 if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
 433                         return ret;
 434                 retries++;
 435                 msleep(100);
 436         }
 437         return ret;
 438 }
 439
 440 /*
 441  * vmbus_set_event - Send an event notification to the parent
 442  */
 443 int vmbus_set_event(struct vmbus_channel *channel)
 444 {
 445         u32 child_relid = channel->offermsg.child_relid;
 446
 447         if (!channel->is_dedicated_interrupt) {
 448                 /* Each u32 represents 32 channels */
 449                 sync_set_bit(child_relid & 31,
 450                         (unsigned long *)vmbus_connection.send_int_page +
 451                         (child_relid >> 5));
 452         }
 453
 454         return hv_signal_event(channel->sig_event);
 455 }