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_WS2008):
  59         default:
  60                 return VERSION_INVAL;
  61         }
  62 }
  63
  64 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  65                                         __u32 version)
  66 {
  67         int ret = 0;
  68         struct vmbus_channel_initiate_contact *msg;
  69         unsigned long flags;
  70         int t;
  71
  72         init_completion(&msginfo->waitevent);
  73
  74         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  75
  76         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  77         msg->vmbus_version_requested = version;
  78         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  79         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages);
  80         msg->monitor_page2 = virt_to_phys(
  81                         (void *)((unsigned long)vmbus_connection.monitor_pages +
  82                                  PAGE_SIZE));
  83
  84         /*
  85          * Add to list before we send the request since we may
  86          * receive the response before returning from this routine
  87          */
  88         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
  89         list_add_tail(&msginfo->msglistentry,
  90                       &vmbus_connection.chn_msg_list);
  91
  92         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
  93
  94         ret = vmbus_post_msg(msg,
  95                                sizeof(struct vmbus_channel_initiate_contact));
  96         if (ret != 0) {
  97                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
  98                 list_del(&msginfo->msglistentry);
  99                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 100                                         flags);
 101                 return ret;
 102         }
 103
 104         /* Wait for the connection response */
 105         t =  wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
 106         if (t == 0) {
 107                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock,
 108                                 flags);
 109                 list_del(&msginfo->msglistentry);
 110                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 111                                         flags);
 112                 return -ETIMEDOUT;
 113         }
 114
 115         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 116         list_del(&msginfo->msglistentry);
 117         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 118
 119         /* Check if successful */
 120         if (msginfo->response.version_response.version_supported) {
 121                 vmbus_connection.conn_state = CONNECTED;
 122         } else {
 123                 return -ECONNREFUSED;
 124         }
 125
 126         return ret;
 127 }
 128
 129 /*
 130  * vmbus_connect - Sends a connect request on the partition service connection
 131  */
 132 int vmbus_connect(void)
 133 {
 134         int ret = 0;
 135         struct vmbus_channel_msginfo *msginfo = NULL;
 136         __u32 version;
 137
 138         /* Initialize the vmbus connection */
 139         vmbus_connection.conn_state = CONNECTING;
 140         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 141         if (!vmbus_connection.work_queue) {
 142                 ret = -ENOMEM;
 143                 goto cleanup;
 144         }
 145
 146         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 147         spin_lock_init(&vmbus_connection.channelmsg_lock);
 148
 149         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 150         spin_lock_init(&vmbus_connection.channel_lock);
 151
 152         /*
 153          * Setup the vmbus event connection for channel interrupt
 154          * abstraction stuff
 155          */
 156         vmbus_connection.int_page =
 157         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 158         if (vmbus_connection.int_page == NULL) {
 159                 ret = -ENOMEM;
 160                 goto cleanup;
 161         }
 162
 163         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 164         vmbus_connection.send_int_page =
 165                 (void *)((unsigned long)vmbus_connection.int_page +
 166                         (PAGE_SIZE >> 1));
 167
 168         /*
 169          * Setup the monitor notification facility. The 1st page for
 170          * parent->child and the 2nd page for child->parent
 171          */
 172         vmbus_connection.monitor_pages =
 173         (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 1);
 174         if (vmbus_connection.monitor_pages == 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 == 0)
 199                         break;
 200
 201                 version = vmbus_get_next_version(version);
 202         } while (version != VERSION_INVAL);
 203
 204         if (version == VERSION_INVAL)
 205                 goto cleanup;
 206
 207         vmbus_proto_version = version;
 208         pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
 209                     host_info_eax, host_info_ebx >> 16,
 210                     host_info_ebx & 0xFFFF, host_info_ecx,
 211                     host_info_edx >> 24, host_info_edx & 0xFFFFFF,
 212                     version >> 16, version & 0xFFFF);
 213
 214         kfree(msginfo);
 215         return 0;
 216
 217 cleanup:
 218         pr_err("Unable to connect to host\n");
 219         vmbus_connection.conn_state = DISCONNECTED;
 220
 221         if (vmbus_connection.work_queue)
 222                 destroy_workqueue(vmbus_connection.work_queue);
 223
 224         if (vmbus_connection.int_page) {
 225                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 226                 vmbus_connection.int_page = NULL;
 227         }
 228
 229         if (vmbus_connection.monitor_pages) {
 230                 free_pages((unsigned long)vmbus_connection.monitor_pages, 1);
 231                 vmbus_connection.monitor_pages = NULL;
 232         }
 233
 234         kfree(msginfo);
 235
 236         return ret;
 237 }
 238
 239
 240 /*
 241  * relid2channel - Get the channel object given its
 242  * child relative id (ie channel id)
 243  */
 244 struct vmbus_channel *relid2channel(u32 relid)
 245 {
 246         struct vmbus_channel *channel;
 247         struct vmbus_channel *found_channel  = NULL;
 248         unsigned long flags;
 249
 250         spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 251         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 252                 if (channel->offermsg.child_relid == relid) {
 253                         found_channel = channel;
 254                         break;
 255                 }
 256         }
 257         spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 258
 259         return found_channel;
 260 }
 261
 262 /*
 263  * process_chn_event - Process a channel event notification
 264  */
 265 static void process_chn_event(u32 relid)
 266 {
 267         struct vmbus_channel *channel;
 268         unsigned long flags;
 269         void *arg;
 270         bool read_state;
 271         u32 bytes_to_read;
 272
 273         /*
 274          * Find the channel based on this relid and invokes the
 275          * channel callback to process the event
 276          */
 277         channel = relid2channel(relid);
 278
 279         if (!channel) {
 280                 pr_err("channel not found for relid - %u\n", relid);
 281                 return;
 282         }
 283
 284         /*
 285          * A channel once created is persistent even when there
 286          * is no driver handling the device. An unloading driver
 287          * sets the onchannel_callback to NULL under the
 288          * protection of the channel inbound_lock. Thus, checking
 289          * and invoking the driver specific callback takes care of
 290          * orderly unloading of the driver.
 291          */
 292
 293         spin_lock_irqsave(&channel->inbound_lock, flags);
 294         if (channel->onchannel_callback != NULL) {
 295                 arg = channel->channel_callback_context;
 296                 read_state = channel->batched_reading;
 297                 /*
 298                  * This callback reads the messages sent by the host.
 299                  * We can optimize host to guest signaling by ensuring:
 300                  * 1. While reading the channel, we disable interrupts from
 301                  *    host.
 302                  * 2. Ensure that we process all posted messages from the host
 303                  *    before returning from this callback.
 304                  * 3. Once we return, enable signaling from the host. Once this
 305                  *    state is set we check to see if additional packets are
 306                  *    available to read. In this case we repeat the process.
 307                  */
 308
 309                 do {
 310                         hv_begin_read(&channel->inbound);
 311                         channel->onchannel_callback(arg);
 312                         bytes_to_read = hv_end_read(&channel->inbound);
 313                 } while (read_state && (bytes_to_read != 0));
 314         } else {
 315                 pr_err("no channel callback for relid - %u\n", relid);
 316         }
 317
 318         spin_unlock_irqrestore(&channel->inbound_lock, flags);
 319 }
 320
 321 /*
 322  * vmbus_on_event - Handler for events
 323  */
 324 void vmbus_on_event(unsigned long data)
 325 {
 326         u32 dword;
 327         u32 maxdword;
 328         int bit;
 329         u32 relid;
 330         u32 *recv_int_page = NULL;
 331         void *page_addr;
 332         int cpu = smp_processor_id();
 333         union hv_synic_event_flags *event;
 334
 335         if ((vmbus_proto_version == VERSION_WS2008) ||
 336                 (vmbus_proto_version == VERSION_WIN7)) {
 337                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 338                 recv_int_page = vmbus_connection.recv_int_page;
 339         } else {
 340                 /*
 341                  * When the host is win8 and beyond, the event page
 342                  * can be directly checked to get the id of the channel
 343                  * that has the interrupt pending.
 344                  */
 345                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 346                 page_addr = hv_context.synic_event_page[cpu];
 347                 event = (union hv_synic_event_flags *)page_addr +
 348                                                  VMBUS_MESSAGE_SINT;
 349                 recv_int_page = event->flags32;
 350         }
 351
 352
 353
 354         /* Check events */
 355         if (!recv_int_page)
 356                 return;
 357         for (dword = 0; dword < maxdword; dword++) {
 358                 if (!recv_int_page[dword])
 359                         continue;
 360                 for (bit = 0; bit < 32; bit++) {
 361                         if (sync_test_and_clear_bit(bit,
 362                                 (unsigned long *)&recv_int_page[dword])) {
 363                                 relid = (dword << 5) + bit;
 364
 365                                 if (relid == 0)
 366                                         /*
 367                                          * Special case - vmbus
 368                                          * channel protocol msg
 369                                          */
 370                                         continue;
 371
 372                                 process_chn_event(relid);
 373                         }
 374                 }
 375         }
 376 }
 377
 378 /*
 379  * vmbus_post_msg - Send a msg on the vmbus's message connection
 380  */
 381 int vmbus_post_msg(void *buffer, size_t buflen)
 382 {
 383         union hv_connection_id conn_id;
 384         int ret = 0;
 385         int retries = 0;
 386
 387         conn_id.asu32 = 0;
 388         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 389
 390         /*
 391          * hv_post_message() can have transient failures because of
 392          * insufficient resources. Retry the operation a couple of
 393          * times before giving up.
 394          */
 395         while (retries < 3) {
 396                 ret =  hv_post_message(conn_id, 1, buffer, buflen);
 397                 if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
 398                         return ret;
 399                 retries++;
 400                 msleep(100);
 401         }
 402         return ret;
 403 }
 404
 405 /*
 406  * vmbus_set_event - Send an event notification to the parent
 407  */
 408 int vmbus_set_event(struct vmbus_channel *channel)
 409 {
 410         u32 child_relid = channel->offermsg.child_relid;
 411
 412         if (!channel->is_dedicated_interrupt) {
 413                 /* Each u32 represents 32 channels */
 414                 sync_set_bit(child_relid & 31,
 415                         (unsigned long *)vmbus_connection.send_int_page +
 416                         (child_relid >> 5));
 417         }
 418
 419         return hv_signal_event(channel->sig_event);
 420 }