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         else
  99                 msg->target_vcpu = 0;
 100
 101         /*
 102          * Add to list before we send the request since we may
 103          * receive the response before returning from this routine
 104          */
 105         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 106         list_add_tail(&msginfo->msglistentry,
 107                       &vmbus_connection.chn_msg_list);
 108
 109         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 110
 111         ret = vmbus_post_msg(msg,
 112                              sizeof(struct vmbus_channel_initiate_contact),
 113                              true);
 114         if (ret != 0) {
 115                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 116                 list_del(&msginfo->msglistentry);
 117                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 118                                         flags);
 119                 return ret;
 120         }
 121
 122         /* Wait for the connection response */
 123         wait_for_completion(&msginfo->waitevent);
 124
 125         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 126         list_del(&msginfo->msglistentry);
 127         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 128
 129         /* Check if successful */
 130         if (msginfo->response.version_response.version_supported) {
 131                 vmbus_connection.conn_state = CONNECTED;
 132         } else {
 133                 return -ECONNREFUSED;
 134         }
 135
 136         return ret;
 137 }
 138
 139 /*
 140  * vmbus_connect - Sends a connect request on the partition service connection
 141  */
 142 int vmbus_connect(void)
 143 {
 144         int ret = 0;
 145         struct vmbus_channel_msginfo *msginfo = NULL;
 146         __u32 version;
 147
 148         /* Initialize the vmbus connection */
 149         vmbus_connection.conn_state = CONNECTING;
 150         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 151         if (!vmbus_connection.work_queue) {
 152                 ret = -ENOMEM;
 153                 goto cleanup;
 154         }
 155
 156         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 157         spin_lock_init(&vmbus_connection.channelmsg_lock);
 158
 159         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 160         mutex_init(&vmbus_connection.channel_mutex);
 161
 162         /*
 163          * Setup the vmbus event connection for channel interrupt
 164          * abstraction stuff
 165          */
 166         vmbus_connection.int_page =
 167         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 168         if (vmbus_connection.int_page == NULL) {
 169                 ret = -ENOMEM;
 170                 goto cleanup;
 171         }
 172
 173         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 174         vmbus_connection.send_int_page =
 175                 (void *)((unsigned long)vmbus_connection.int_page +
 176                         (PAGE_SIZE >> 1));
 177
 178         /*
 179          * Setup the monitor notification facility. The 1st page for
 180          * parent->child and the 2nd page for child->parent
 181          */
 182         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 183         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 184         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 185             (vmbus_connection.monitor_pages[1] == NULL)) {
 186                 ret = -ENOMEM;
 187                 goto cleanup;
 188         }
 189
 190         msginfo = kzalloc(sizeof(*msginfo) +
 191                           sizeof(struct vmbus_channel_initiate_contact),
 192                           GFP_KERNEL);
 193         if (msginfo == NULL) {
 194                 ret = -ENOMEM;
 195                 goto cleanup;
 196         }
 197
 198         /*
 199          * Negotiate a compatible VMBUS version number with the
 200          * host. We start with the highest number we can support
 201          * and work our way down until we negotiate a compatible
 202          * version.
 203          */
 204
 205         version = VERSION_CURRENT;
 206
 207         do {
 208                 ret = vmbus_negotiate_version(msginfo, version);
 209                 if (ret == -ETIMEDOUT)
 210                         goto cleanup;
 211
 212                 if (vmbus_connection.conn_state == CONNECTED)
 213                         break;
 214
 215                 version = vmbus_get_next_version(version);
 216         } while (version != VERSION_INVAL);
 217
 218         if (version == VERSION_INVAL)
 219                 goto cleanup;
 220
 221         vmbus_proto_version = version;
 222         pr_info("Vmbus version:%d.%d\n",
 223                 version >> 16, version & 0xFFFF);
 224
 225         kfree(msginfo);
 226         return 0;
 227
 228 cleanup:
 229         pr_err("Unable to connect to host\n");
 230
 231         vmbus_connection.conn_state = DISCONNECTED;
 232         vmbus_disconnect();
 233
 234         kfree(msginfo);
 235
 236         return ret;
 237 }
 238
 239 void vmbus_disconnect(void)
 240 {
 241         /*
 242          * First send the unload request to the host.
 243          */
 244         vmbus_initiate_unload(false);
 245
 246         if (vmbus_connection.work_queue) {
 247                 drain_workqueue(vmbus_connection.work_queue);
 248                 destroy_workqueue(vmbus_connection.work_queue);
 249         }
 250
 251         if (vmbus_connection.int_page) {
 252                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 253                 vmbus_connection.int_page = NULL;
 254         }
 255
 256         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 257         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 258         vmbus_connection.monitor_pages[0] = NULL;
 259         vmbus_connection.monitor_pages[1] = NULL;
 260 }
 261
 262 /*
 263  * relid2channel - Get the channel object given its
 264  * child relative id (ie channel id)
 265  */
 266 struct vmbus_channel *relid2channel(u32 relid)
 267 {
 268         struct vmbus_channel *channel;
 269         struct vmbus_channel *found_channel  = NULL;
 270         struct list_head *cur, *tmp;
 271         struct vmbus_channel *cur_sc;
 272
 273         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 274
 275         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 276                 if (channel->offermsg.child_relid == relid) {
 277                         found_channel = channel;
 278                         break;
 279                 } else if (!list_empty(&channel->sc_list)) {
 280                         /*
 281                          * Deal with sub-channels.
 282                          */
 283                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 284                                 cur_sc = list_entry(cur, struct vmbus_channel,
 285                                                         sc_list);
 286                                 if (cur_sc->offermsg.child_relid == relid) {
 287                                         found_channel = cur_sc;
 288                                         break;
 289                                 }
 290                         }
 291                 }
 292         }
 293
 294         return found_channel;
 295 }
 296
 297 /*
 298  * vmbus_on_event - Process a channel event notification
 299  */
 300 void vmbus_on_event(unsigned long data)
 301 {
 302         struct vmbus_channel *channel = (void *) data;
 303         void (*callback_fn)(void *);
 304
 305         /*
 306          * A channel once created is persistent even when there
 307          * is no driver handling the device. An unloading driver
 308          * sets the onchannel_callback to NULL on the same CPU
 309          * as where this interrupt is handled (in an interrupt context).
 310          * Thus, checking and invoking the driver specific callback takes
 311          * care of orderly unloading of the driver.
 312          */
 313         callback_fn = READ_ONCE(channel->onchannel_callback);
 314         if (unlikely(callback_fn == NULL))
 315                 return;
 316
 317         (*callback_fn)(channel->channel_callback_context);
 318
 319         if (channel->callback_mode == HV_CALL_BATCHED) {
 320                 /*
 321                  * This callback reads the messages sent by the host.
 322                  * We can optimize host to guest signaling by ensuring:
 323                  * 1. While reading the channel, we disable interrupts from
 324                  *    host.
 325                  * 2. Ensure that we process all posted messages from the host
 326                  *    before returning from this callback.
 327                  * 3. Once we return, enable signaling from the host. Once this
 328                  *    state is set we check to see if additional packets are
 329                  *    available to read. In this case we repeat the process.
 330                  */
 331                 if (hv_end_read(&channel->inbound) != 0) {
 332                         hv_begin_read(&channel->inbound);
 333
 334                         tasklet_schedule(&channel->callback_event);
 335                 }
 336         }
 337 }
 338
 339 /*
 340  * vmbus_post_msg - Send a msg on the vmbus's message connection
 341  */
 342 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 343 {
 344         union hv_connection_id conn_id;
 345         int ret = 0;
 346         int retries = 0;
 347         u32 usec = 1;
 348
 349         conn_id.asu32 = 0;
 350         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 351
 352         /*
 353          * hv_post_message() can have transient failures because of
 354          * insufficient resources. Retry the operation a couple of
 355          * times before giving up.
 356          */
 357         while (retries < 100) {
 358                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 359
 360                 switch (ret) {
 361                 case HV_STATUS_INVALID_CONNECTION_ID:
 362                         /*
 363                          * We could get this if we send messages too
 364                          * frequently.
 365                          */
 366                         ret = -EAGAIN;
 367                         break;
 368                 case HV_STATUS_INSUFFICIENT_MEMORY:
 369                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 370                         ret = -ENOMEM;
 371                         break;
 372                 case HV_STATUS_SUCCESS:
 373                         return ret;
 374                 default:
 375                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 376                         return -EINVAL;
 377                 }
 378
 379                 retries++;
 380                 if (can_sleep && usec > 1000)
 381                         msleep(usec / 1000);
 382                 else if (usec < MAX_UDELAY_MS * 1000)
 383                         udelay(usec);
 384                 else
 385                         mdelay(usec / 1000);
 386
 387                 if (usec < 256000)
 388                         usec *= 2;
 389         }
 390         return ret;
 391 }
 392
 393 /*
 394  * vmbus_set_event - Send an event notification to the parent
 395  */
 396 void vmbus_set_event(struct vmbus_channel *channel)
 397 {
 398         u32 child_relid = channel->offermsg.child_relid;
 399
 400         if (!channel->is_dedicated_interrupt)
 401                 vmbus_send_interrupt(child_relid);
 402
 403         hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
 404 }
 405 EXPORT_SYMBOL_GPL(vmbus_set_event);