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[smp_processor_id()];
  98                 vmbus_connection.connect_cpu = smp_processor_id();
  99         } else {
 100                 msg->target_vcpu = 0;
 101                 vmbus_connection.connect_cpu = 0;
 102         }
 103
 104         /*
 105          * Add to list before we send the request since we may
 106          * receive the response before returning from this routine
 107          */
 108         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 109         list_add_tail(&msginfo->msglistentry,
 110                       &vmbus_connection.chn_msg_list);
 111
 112         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 113
 114         ret = vmbus_post_msg(msg,
 115                              sizeof(struct vmbus_channel_initiate_contact),
 116                              true);
 117         if (ret != 0) {
 118                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 119                 list_del(&msginfo->msglistentry);
 120                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 121                                         flags);
 122                 return ret;
 123         }
 124
 125         /* Wait for the connection response */
 126         wait_for_completion(&msginfo->waitevent);
 127
 128         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 129         list_del(&msginfo->msglistentry);
 130         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 131
 132         /* Check if successful */
 133         if (msginfo->response.version_response.version_supported) {
 134                 vmbus_connection.conn_state = CONNECTED;
 135         } else {
 136                 return -ECONNREFUSED;
 137         }
 138
 139         return ret;
 140 }
 141
 142 /*
 143  * vmbus_connect - Sends a connect request on the partition service connection
 144  */
 145 int vmbus_connect(void)
 146 {
 147         int ret = 0;
 148         struct vmbus_channel_msginfo *msginfo = NULL;
 149         __u32 version;
 150
 151         /* Initialize the vmbus connection */
 152         vmbus_connection.conn_state = CONNECTING;
 153         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 154         if (!vmbus_connection.work_queue) {
 155                 ret = -ENOMEM;
 156                 goto cleanup;
 157         }
 158
 159         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 160         spin_lock_init(&vmbus_connection.channelmsg_lock);
 161
 162         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 163         mutex_init(&vmbus_connection.channel_mutex);
 164
 165         /*
 166          * Setup the vmbus event connection for channel interrupt
 167          * abstraction stuff
 168          */
 169         vmbus_connection.int_page =
 170         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 171         if (vmbus_connection.int_page == NULL) {
 172                 ret = -ENOMEM;
 173                 goto cleanup;
 174         }
 175
 176         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 177         vmbus_connection.send_int_page =
 178                 (void *)((unsigned long)vmbus_connection.int_page +
 179                         (PAGE_SIZE >> 1));
 180
 181         /*
 182          * Setup the monitor notification facility. The 1st page for
 183          * parent->child and the 2nd page for child->parent
 184          */
 185         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 186         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 187         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 188             (vmbus_connection.monitor_pages[1] == NULL)) {
 189                 ret = -ENOMEM;
 190                 goto cleanup;
 191         }
 192
 193         msginfo = kzalloc(sizeof(*msginfo) +
 194                           sizeof(struct vmbus_channel_initiate_contact),
 195                           GFP_KERNEL);
 196         if (msginfo == NULL) {
 197                 ret = -ENOMEM;
 198                 goto cleanup;
 199         }
 200
 201         /*
 202          * Negotiate a compatible VMBUS version number with the
 203          * host. We start with the highest number we can support
 204          * and work our way down until we negotiate a compatible
 205          * version.
 206          */
 207
 208         version = VERSION_CURRENT;
 209
 210         do {
 211                 ret = vmbus_negotiate_version(msginfo, version);
 212                 if (ret == -ETIMEDOUT)
 213                         goto cleanup;
 214
 215                 if (vmbus_connection.conn_state == CONNECTED)
 216                         break;
 217
 218                 version = vmbus_get_next_version(version);
 219         } while (version != VERSION_INVAL);
 220
 221         if (version == VERSION_INVAL)
 222                 goto cleanup;
 223
 224         vmbus_proto_version = version;
 225         pr_info("Vmbus version:%d.%d\n",
 226                 version >> 16, version & 0xFFFF);
 227
 228         kfree(msginfo);
 229         return 0;
 230
 231 cleanup:
 232         pr_err("Unable to connect to host\n");
 233
 234         vmbus_connection.conn_state = DISCONNECTED;
 235         vmbus_disconnect();
 236
 237         kfree(msginfo);
 238
 239         return ret;
 240 }
 241
 242 void vmbus_disconnect(void)
 243 {
 244         /*
 245          * First send the unload request to the host.
 246          */
 247         vmbus_initiate_unload(false);
 248
 249         if (vmbus_connection.work_queue) {
 250                 drain_workqueue(vmbus_connection.work_queue);
 251                 destroy_workqueue(vmbus_connection.work_queue);
 252         }
 253
 254         if (vmbus_connection.int_page) {
 255                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 256                 vmbus_connection.int_page = NULL;
 257         }
 258
 259         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 260         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 261         vmbus_connection.monitor_pages[0] = NULL;
 262         vmbus_connection.monitor_pages[1] = NULL;
 263 }
 264
 265 /*
 266  * relid2channel - Get the channel object given its
 267  * child relative id (ie channel id)
 268  */
 269 struct vmbus_channel *relid2channel(u32 relid)
 270 {
 271         struct vmbus_channel *channel;
 272         struct vmbus_channel *found_channel  = NULL;
 273         struct list_head *cur, *tmp;
 274         struct vmbus_channel *cur_sc;
 275
 276         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 277
 278         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 279                 if (channel->offermsg.child_relid == relid) {
 280                         found_channel = channel;
 281                         break;
 282                 } else if (!list_empty(&channel->sc_list)) {
 283                         /*
 284                          * Deal with sub-channels.
 285                          */
 286                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 287                                 cur_sc = list_entry(cur, struct vmbus_channel,
 288                                                         sc_list);
 289                                 if (cur_sc->offermsg.child_relid == relid) {
 290                                         found_channel = cur_sc;
 291                                         break;
 292                                 }
 293                         }
 294                 }
 295         }
 296
 297         return found_channel;
 298 }
 299
 300 /*
 301  * vmbus_on_event - Process a channel event notification
 302  *
 303  * For batched channels (default) optimize host to guest signaling
 304  * by ensuring:
 305  * 1. While reading the channel, we disable interrupts from host.
 306  * 2. Ensure that we process all posted messages from the host
 307  *    before returning from this callback.
 308  * 3. Once we return, enable signaling from the host. Once this
 309  *    state is set we check to see if additional packets are
 310  *    available to read. In this case we repeat the process.
 311  *    If this tasklet has been running for a long time
 312  *    then reschedule ourselves.
 313  */
 314 void vmbus_on_event(unsigned long data)
 315 {
 316         struct vmbus_channel *channel = (void *) data;
 317         unsigned long time_limit = jiffies + 2;
 318
 319         do {
 320                 void (*callback_fn)(void *);
 321
 322                 /* A channel once created is persistent even when
 323                  * there is no driver handling the device. An
 324                  * unloading driver sets the onchannel_callback to NULL.
 325                  */
 326                 callback_fn = READ_ONCE(channel->onchannel_callback);
 327                 if (unlikely(callback_fn == NULL))
 328                         return;
 329
 330                 (*callback_fn)(channel->channel_callback_context);
 331
 332                 if (channel->callback_mode != HV_CALL_BATCHED)
 333                         return;
 334
 335                 if (likely(hv_end_read(&channel->inbound) == 0))
 336                         return;
 337
 338                 hv_begin_read(&channel->inbound);
 339         } while (likely(time_before(jiffies, time_limit)));
 340
 341         /* The time limit (2 jiffies) has been reached */
 342         tasklet_schedule(&channel->callback_event);
 343 }
 344
 345 /*
 346  * vmbus_post_msg - Send a msg on the vmbus's message connection
 347  */
 348 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 349 {
 350         union hv_connection_id conn_id;
 351         int ret = 0;
 352         int retries = 0;
 353         u32 usec = 1;
 354
 355         conn_id.asu32 = 0;
 356         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 357
 358         /*
 359          * hv_post_message() can have transient failures because of
 360          * insufficient resources. Retry the operation a couple of
 361          * times before giving up.
 362          */
 363         while (retries < 100) {
 364                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 365
 366                 switch (ret) {
 367                 case HV_STATUS_INVALID_CONNECTION_ID:
 368                         /*
 369                          * We could get this if we send messages too
 370                          * frequently.
 371                          */
 372                         ret = -EAGAIN;
 373                         break;
 374                 case HV_STATUS_INSUFFICIENT_MEMORY:
 375                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 376                         ret = -ENOBUFS;
 377                         break;
 378                 case HV_STATUS_SUCCESS:
 379                         return ret;
 380                 default:
 381                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 382                         return -EINVAL;
 383                 }
 384
 385                 retries++;
 386                 if (can_sleep && usec > 1000)
 387                         msleep(usec / 1000);
 388                 else if (usec < MAX_UDELAY_MS * 1000)
 389                         udelay(usec);
 390                 else
 391                         mdelay(usec / 1000);
 392
 393                 if (retries < 22)
 394                         usec *= 2;
 395         }
 396         return ret;
 397 }
 398
 399 /*
 400  * vmbus_set_event - Send an event notification to the parent
 401  */
 402 void vmbus_set_event(struct vmbus_channel *channel)
 403 {
 404         u32 child_relid = channel->offermsg.child_relid;
 405
 406         if (!channel->is_dedicated_interrupt)
 407                 vmbus_send_interrupt(child_relid);
 408
 409         hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
 410 }
 411 EXPORT_SYMBOL_GPL(vmbus_set_event);