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 <asm/mshyperv.h>
  36
  37 #include "hyperv_vmbus.h"
  38
  39
  40 struct vmbus_connection vmbus_connection = {
  41         .conn_state             = DISCONNECTED,
  42         .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),
  43 };
  44 EXPORT_SYMBOL_GPL(vmbus_connection);
  45
  46 /*
  47  * Negotiated protocol version with the host.
  48  */
  49 __u32 vmbus_proto_version;
  50 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  51
  52 static __u32 vmbus_get_next_version(__u32 current_version)
  53 {
  54         switch (current_version) {
  55         case (VERSION_WIN7):
  56                 return VERSION_WS2008;
  57
  58         case (VERSION_WIN8):
  59                 return VERSION_WIN7;
  60
  61         case (VERSION_WIN8_1):
  62                 return VERSION_WIN8;
  63
  64         case (VERSION_WIN10):
  65                 return VERSION_WIN8_1;
  66
  67         case (VERSION_WS2008):
  68         default:
  69                 return VERSION_INVAL;
  70         }
  71 }
  72
  73 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  74                                         __u32 version)
  75 {
  76         int ret = 0;
  77         struct vmbus_channel_initiate_contact *msg;
  78         unsigned long flags;
  79
  80         init_completion(&msginfo->waitevent);
  81
  82         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  83
  84         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  85         msg->vmbus_version_requested = version;
  86         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  87         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
  88         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
  89         /*
  90          * We want all channel messages to be delivered on CPU 0.
  91          * This has been the behavior pre-win8. This is not
  92          * perf issue and having all channel messages delivered on CPU 0
  93          * would be ok.
  94          * For post win8 hosts, we support receiving channel messagges on
  95          * all the CPUs. This is needed for kexec to work correctly where
  96          * the CPU attempting to connect may not be CPU 0.
  97          */
  98         if (version >= VERSION_WIN8_1) {
  99                 msg->target_vcpu =
 100                         hv_cpu_number_to_vp_number(smp_processor_id());
 101                 vmbus_connection.connect_cpu = smp_processor_id();
 102         } else {
 103                 msg->target_vcpu = 0;
 104                 vmbus_connection.connect_cpu = 0;
 105         }
 106
 107         /*
 108          * Add to list before we send the request since we may
 109          * receive the response before returning from this routine
 110          */
 111         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 112         list_add_tail(&msginfo->msglistentry,
 113                       &vmbus_connection.chn_msg_list);
 114
 115         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 116
 117         ret = vmbus_post_msg(msg,
 118                              sizeof(struct vmbus_channel_initiate_contact),
 119                              true);
 120         if (ret != 0) {
 121                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 122                 list_del(&msginfo->msglistentry);
 123                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 124                                         flags);
 125                 return ret;
 126         }
 127
 128         /* Wait for the connection response */
 129         wait_for_completion(&msginfo->waitevent);
 130
 131         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 132         list_del(&msginfo->msglistentry);
 133         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 134
 135         /* Check if successful */
 136         if (msginfo->response.version_response.version_supported) {
 137                 vmbus_connection.conn_state = CONNECTED;
 138         } else {
 139                 return -ECONNREFUSED;
 140         }
 141
 142         return ret;
 143 }
 144
 145 /*
 146  * vmbus_connect - Sends a connect request on the partition service connection
 147  */
 148 int vmbus_connect(void)
 149 {
 150         int ret = 0;
 151         struct vmbus_channel_msginfo *msginfo = NULL;
 152         __u32 version;
 153
 154         /* Initialize the vmbus connection */
 155         vmbus_connection.conn_state = CONNECTING;
 156         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 157         if (!vmbus_connection.work_queue) {
 158                 ret = -ENOMEM;
 159                 goto cleanup;
 160         }
 161
 162         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 163         spin_lock_init(&vmbus_connection.channelmsg_lock);
 164
 165         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 166         mutex_init(&vmbus_connection.channel_mutex);
 167
 168         /*
 169          * Setup the vmbus event connection for channel interrupt
 170          * abstraction stuff
 171          */
 172         vmbus_connection.int_page =
 173         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 174         if (vmbus_connection.int_page == NULL) {
 175                 ret = -ENOMEM;
 176                 goto cleanup;
 177         }
 178
 179         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 180         vmbus_connection.send_int_page =
 181                 (void *)((unsigned long)vmbus_connection.int_page +
 182                         (PAGE_SIZE >> 1));
 183
 184         /*
 185          * Setup the monitor notification facility. The 1st page for
 186          * parent->child and the 2nd page for child->parent
 187          */
 188         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 189         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 190         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 191             (vmbus_connection.monitor_pages[1] == NULL)) {
 192                 ret = -ENOMEM;
 193                 goto cleanup;
 194         }
 195
 196         msginfo = kzalloc(sizeof(*msginfo) +
 197                           sizeof(struct vmbus_channel_initiate_contact),
 198                           GFP_KERNEL);
 199         if (msginfo == NULL) {
 200                 ret = -ENOMEM;
 201                 goto cleanup;
 202         }
 203
 204         /*
 205          * Negotiate a compatible VMBUS version number with the
 206          * host. We start with the highest number we can support
 207          * and work our way down until we negotiate a compatible
 208          * version.
 209          */
 210
 211         version = VERSION_CURRENT;
 212
 213         do {
 214                 ret = vmbus_negotiate_version(msginfo, version);
 215                 if (ret == -ETIMEDOUT)
 216                         goto cleanup;
 217
 218                 if (vmbus_connection.conn_state == CONNECTED)
 219                         break;
 220
 221                 version = vmbus_get_next_version(version);
 222         } while (version != VERSION_INVAL);
 223
 224         if (version == VERSION_INVAL)
 225                 goto cleanup;
 226
 227         vmbus_proto_version = version;
 228         pr_info("Vmbus version:%d.%d\n",
 229                 version >> 16, version & 0xFFFF);
 230
 231         kfree(msginfo);
 232         return 0;
 233
 234 cleanup:
 235         pr_err("Unable to connect to host\n");
 236
 237         vmbus_connection.conn_state = DISCONNECTED;
 238         vmbus_disconnect();
 239
 240         kfree(msginfo);
 241
 242         return ret;
 243 }
 244
 245 void vmbus_disconnect(void)
 246 {
 247         /*
 248          * First send the unload request to the host.
 249          */
 250         vmbus_initiate_unload(false);
 251
 252         if (vmbus_connection.work_queue) {
 253                 drain_workqueue(vmbus_connection.work_queue);
 254                 destroy_workqueue(vmbus_connection.work_queue);
 255         }
 256
 257         if (vmbus_connection.int_page) {
 258                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 259                 vmbus_connection.int_page = NULL;
 260         }
 261
 262         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 263         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 264         vmbus_connection.monitor_pages[0] = NULL;
 265         vmbus_connection.monitor_pages[1] = NULL;
 266 }
 267
 268 /*
 269  * relid2channel - Get the channel object given its
 270  * child relative id (ie channel id)
 271  */
 272 struct vmbus_channel *relid2channel(u32 relid)
 273 {
 274         struct vmbus_channel *channel;
 275         struct vmbus_channel *found_channel  = NULL;
 276         struct list_head *cur, *tmp;
 277         struct vmbus_channel *cur_sc;
 278
 279         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 280
 281         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 282                 if (channel->offermsg.child_relid == relid) {
 283                         found_channel = channel;
 284                         break;
 285                 } else if (!list_empty(&channel->sc_list)) {
 286                         /*
 287                          * Deal with sub-channels.
 288                          */
 289                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 290                                 cur_sc = list_entry(cur, struct vmbus_channel,
 291                                                         sc_list);
 292                                 if (cur_sc->offermsg.child_relid == relid) {
 293                                         found_channel = cur_sc;
 294                                         break;
 295                                 }
 296                         }
 297                 }
 298         }
 299
 300         return found_channel;
 301 }
 302
 303 /*
 304  * vmbus_on_event - Process a channel event notification
 305  *
 306  * For batched channels (default) optimize host to guest signaling
 307  * by ensuring:
 308  * 1. While reading the channel, we disable interrupts from host.
 309  * 2. Ensure that we process all posted messages from the host
 310  *    before returning from this callback.
 311  * 3. Once we return, enable signaling from the host. Once this
 312  *    state is set we check to see if additional packets are
 313  *    available to read. In this case we repeat the process.
 314  *    If this tasklet has been running for a long time
 315  *    then reschedule ourselves.
 316  */
 317 void vmbus_on_event(unsigned long data)
 318 {
 319         struct vmbus_channel *channel = (void *) data;
 320         unsigned long time_limit = jiffies + 2;
 321
 322         do {
 323                 void (*callback_fn)(void *);
 324
 325                 /* A channel once created is persistent even when
 326                  * there is no driver handling the device. An
 327                  * unloading driver sets the onchannel_callback to NULL.
 328                  */
 329                 callback_fn = READ_ONCE(channel->onchannel_callback);
 330                 if (unlikely(callback_fn == NULL))
 331                         return;
 332
 333                 (*callback_fn)(channel->channel_callback_context);
 334
 335                 if (channel->callback_mode != HV_CALL_BATCHED)
 336                         return;
 337
 338                 if (likely(hv_end_read(&channel->inbound) == 0))
 339                         return;
 340
 341                 hv_begin_read(&channel->inbound);
 342         } while (likely(time_before(jiffies, time_limit)));
 343
 344         /* The time limit (2 jiffies) has been reached */
 345         tasklet_schedule(&channel->callback_event);
 346 }
 347
 348 /*
 349  * vmbus_post_msg - Send a msg on the vmbus's message connection
 350  */
 351 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 352 {
 353         union hv_connection_id conn_id;
 354         int ret = 0;
 355         int retries = 0;
 356         u32 usec = 1;
 357
 358         conn_id.asu32 = 0;
 359         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 360
 361         /*
 362          * hv_post_message() can have transient failures because of
 363          * insufficient resources. Retry the operation a couple of
 364          * times before giving up.
 365          */
 366         while (retries < 100) {
 367                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 368
 369                 switch (ret) {
 370                 case HV_STATUS_INVALID_CONNECTION_ID:
 371                         /*
 372                          * We could get this if we send messages too
 373                          * frequently.
 374                          */
 375                         ret = -EAGAIN;
 376                         break;
 377                 case HV_STATUS_INSUFFICIENT_MEMORY:
 378                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 379                         ret = -ENOBUFS;
 380                         break;
 381                 case HV_STATUS_SUCCESS:
 382                         return ret;
 383                 default:
 384                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 385                         return -EINVAL;
 386                 }
 387
 388                 retries++;
 389                 if (can_sleep && usec > 1000)
 390                         msleep(usec / 1000);
 391                 else if (usec < MAX_UDELAY_MS * 1000)
 392                         udelay(usec);
 393                 else
 394                         mdelay(usec / 1000);
 395
 396                 if (retries < 22)
 397                         usec *= 2;
 398         }
 399         return ret;
 400 }
 401
 402 /*
 403  * vmbus_set_event - Send an event notification to the parent
 404  */
 405 void vmbus_set_event(struct vmbus_channel *channel)
 406 {
 407         u32 child_relid = channel->offermsg.child_relid;
 408
 409         if (!channel->is_dedicated_interrupt)
 410                 vmbus_send_interrupt(child_relid);
 411
 412         hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 413 }
 414 EXPORT_SYMBOL_GPL(vmbus_set_event);