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         unsigned int cur_cpu;
  78         struct vmbus_channel_initiate_contact *msg;
  79         unsigned long flags;
  80
  81         init_completion(&msginfo->waitevent);
  82
  83         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  84
  85         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  86         msg->vmbus_version_requested = version;
  87         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  88         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
  89         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
  90         /*
  91          * We want all channel messages to be delivered on CPU 0.
  92          * This has been the behavior pre-win8. This is not
  93          * perf issue and having all channel messages delivered on CPU 0
  94          * would be ok.
  95          * For post win8 hosts, we support receiving channel messagges on
  96          * all the CPUs. This is needed for kexec to work correctly where
  97          * the CPU attempting to connect may not be CPU 0.
  98          */
  99         if (version >= VERSION_WIN8_1) {
 100                 cur_cpu = get_cpu();
 101                 msg->target_vcpu = hv_cpu_number_to_vp_number(cur_cpu);
 102                 vmbus_connection.connect_cpu = cur_cpu;
 103                 put_cpu();
 104         } else {
 105                 msg->target_vcpu = 0;
 106                 vmbus_connection.connect_cpu = 0;
 107         }
 108
 109         /*
 110          * Add to list before we send the request since we may
 111          * receive the response before returning from this routine
 112          */
 113         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 114         list_add_tail(&msginfo->msglistentry,
 115                       &vmbus_connection.chn_msg_list);
 116
 117         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 118
 119         ret = vmbus_post_msg(msg,
 120                              sizeof(struct vmbus_channel_initiate_contact),
 121                              true);
 122         if (ret != 0) {
 123                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 124                 list_del(&msginfo->msglistentry);
 125                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
 126                                         flags);
 127                 return ret;
 128         }
 129
 130         /* Wait for the connection response */
 131         wait_for_completion(&msginfo->waitevent);
 132
 133         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 134         list_del(&msginfo->msglistentry);
 135         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 136
 137         /* Check if successful */
 138         if (msginfo->response.version_response.version_supported) {
 139                 vmbus_connection.conn_state = CONNECTED;
 140         } else {
 141                 return -ECONNREFUSED;
 142         }
 143
 144         return ret;
 145 }
 146
 147 /*
 148  * vmbus_connect - Sends a connect request on the partition service connection
 149  */
 150 int vmbus_connect(void)
 151 {
 152         int ret = 0;
 153         struct vmbus_channel_msginfo *msginfo = NULL;
 154         __u32 version;
 155
 156         /* Initialize the vmbus connection */
 157         vmbus_connection.conn_state = CONNECTING;
 158         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 159         if (!vmbus_connection.work_queue) {
 160                 ret = -ENOMEM;
 161                 goto cleanup;
 162         }
 163
 164         vmbus_connection.handle_primary_chan_wq =
 165                 create_workqueue("hv_pri_chan");
 166         if (!vmbus_connection.handle_primary_chan_wq) {
 167                 ret = -ENOMEM;
 168                 goto cleanup;
 169         }
 170
 171         vmbus_connection.handle_sub_chan_wq =
 172                 create_workqueue("hv_sub_chan");
 173         if (!vmbus_connection.handle_sub_chan_wq) {
 174                 ret = -ENOMEM;
 175                 goto cleanup;
 176         }
 177
 178         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 179         spin_lock_init(&vmbus_connection.channelmsg_lock);
 180
 181         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 182         mutex_init(&vmbus_connection.channel_mutex);
 183
 184         /*
 185          * Setup the vmbus event connection for channel interrupt
 186          * abstraction stuff
 187          */
 188         vmbus_connection.int_page =
 189         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 190         if (vmbus_connection.int_page == NULL) {
 191                 ret = -ENOMEM;
 192                 goto cleanup;
 193         }
 194
 195         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 196         vmbus_connection.send_int_page =
 197                 (void *)((unsigned long)vmbus_connection.int_page +
 198                         (PAGE_SIZE >> 1));
 199
 200         /*
 201          * Setup the monitor notification facility. The 1st page for
 202          * parent->child and the 2nd page for child->parent
 203          */
 204         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 205         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 206         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 207             (vmbus_connection.monitor_pages[1] == NULL)) {
 208                 ret = -ENOMEM;
 209                 goto cleanup;
 210         }
 211
 212         msginfo = kzalloc(sizeof(*msginfo) +
 213                           sizeof(struct vmbus_channel_initiate_contact),
 214                           GFP_KERNEL);
 215         if (msginfo == NULL) {
 216                 ret = -ENOMEM;
 217                 goto cleanup;
 218         }
 219
 220         /*
 221          * Negotiate a compatible VMBUS version number with the
 222          * host. We start with the highest number we can support
 223          * and work our way down until we negotiate a compatible
 224          * version.
 225          */
 226
 227         version = VERSION_CURRENT;
 228
 229         do {
 230                 ret = vmbus_negotiate_version(msginfo, version);
 231                 if (ret == -ETIMEDOUT)
 232                         goto cleanup;
 233
 234                 if (vmbus_connection.conn_state == CONNECTED)
 235                         break;
 236
 237                 version = vmbus_get_next_version(version);
 238         } while (version != VERSION_INVAL);
 239
 240         if (version == VERSION_INVAL)
 241                 goto cleanup;
 242
 243         vmbus_proto_version = version;
 244         pr_info("Vmbus version:%d.%d\n",
 245                 version >> 16, version & 0xFFFF);
 246
 247         kfree(msginfo);
 248         return 0;
 249
 250 cleanup:
 251         pr_err("Unable to connect to host\n");
 252
 253         vmbus_connection.conn_state = DISCONNECTED;
 254         vmbus_disconnect();
 255
 256         kfree(msginfo);
 257
 258         return ret;
 259 }
 260
 261 void vmbus_disconnect(void)
 262 {
 263         /*
 264          * First send the unload request to the host.
 265          */
 266         vmbus_initiate_unload(false);
 267
 268         if (vmbus_connection.handle_sub_chan_wq)
 269                 destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
 270
 271         if (vmbus_connection.handle_primary_chan_wq)
 272                 destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
 273
 274         if (vmbus_connection.work_queue)
 275                 destroy_workqueue(vmbus_connection.work_queue);
 276
 277         if (vmbus_connection.int_page) {
 278                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 279                 vmbus_connection.int_page = NULL;
 280         }
 281
 282         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 283         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 284         vmbus_connection.monitor_pages[0] = NULL;
 285         vmbus_connection.monitor_pages[1] = NULL;
 286 }
 287
 288 /*
 289  * relid2channel - Get the channel object given its
 290  * child relative id (ie channel id)
 291  */
 292 struct vmbus_channel *relid2channel(u32 relid)
 293 {
 294         struct vmbus_channel *channel;
 295         struct vmbus_channel *found_channel  = NULL;
 296         struct list_head *cur, *tmp;
 297         struct vmbus_channel *cur_sc;
 298
 299         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 300
 301         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 302                 if (channel->offermsg.child_relid == relid) {
 303                         found_channel = channel;
 304                         break;
 305                 } else if (!list_empty(&channel->sc_list)) {
 306                         /*
 307                          * Deal with sub-channels.
 308                          */
 309                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 310                                 cur_sc = list_entry(cur, struct vmbus_channel,
 311                                                         sc_list);
 312                                 if (cur_sc->offermsg.child_relid == relid) {
 313                                         found_channel = cur_sc;
 314                                         break;
 315                                 }
 316                         }
 317                 }
 318         }
 319
 320         return found_channel;
 321 }
 322
 323 /*
 324  * vmbus_on_event - Process a channel event notification
 325  *
 326  * For batched channels (default) optimize host to guest signaling
 327  * by ensuring:
 328  * 1. While reading the channel, we disable interrupts from host.
 329  * 2. Ensure that we process all posted messages from the host
 330  *    before returning from this callback.
 331  * 3. Once we return, enable signaling from the host. Once this
 332  *    state is set we check to see if additional packets are
 333  *    available to read. In this case we repeat the process.
 334  *    If this tasklet has been running for a long time
 335  *    then reschedule ourselves.
 336  */
 337 void vmbus_on_event(unsigned long data)
 338 {
 339         struct vmbus_channel *channel = (void *) data;
 340         unsigned long time_limit = jiffies + 2;
 341
 342         do {
 343                 void (*callback_fn)(void *);
 344
 345                 /* A channel once created is persistent even when
 346                  * there is no driver handling the device. An
 347                  * unloading driver sets the onchannel_callback to NULL.
 348                  */
 349                 callback_fn = READ_ONCE(channel->onchannel_callback);
 350                 if (unlikely(callback_fn == NULL))
 351                         return;
 352
 353                 (*callback_fn)(channel->channel_callback_context);
 354
 355                 if (channel->callback_mode != HV_CALL_BATCHED)
 356                         return;
 357
 358                 if (likely(hv_end_read(&channel->inbound) == 0))
 359                         return;
 360
 361                 hv_begin_read(&channel->inbound);
 362         } while (likely(time_before(jiffies, time_limit)));
 363
 364         /* The time limit (2 jiffies) has been reached */
 365         tasklet_schedule(&channel->callback_event);
 366 }
 367
 368 /*
 369  * vmbus_post_msg - Send a msg on the vmbus's message connection
 370  */
 371 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 372 {
 373         union hv_connection_id conn_id;
 374         int ret = 0;
 375         int retries = 0;
 376         u32 usec = 1;
 377
 378         conn_id.asu32 = 0;
 379         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 380
 381         /*
 382          * hv_post_message() can have transient failures because of
 383          * insufficient resources. Retry the operation a couple of
 384          * times before giving up.
 385          */
 386         while (retries < 100) {
 387                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 388
 389                 switch (ret) {
 390                 case HV_STATUS_INVALID_CONNECTION_ID:
 391                         /*
 392                          * We could get this if we send messages too
 393                          * frequently.
 394                          */
 395                         ret = -EAGAIN;
 396                         break;
 397                 case HV_STATUS_INSUFFICIENT_MEMORY:
 398                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 399                         ret = -ENOBUFS;
 400                         break;
 401                 case HV_STATUS_SUCCESS:
 402                         return ret;
 403                 default:
 404                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 405                         return -EINVAL;
 406                 }
 407
 408                 retries++;
 409                 if (can_sleep && usec > 1000)
 410                         msleep(usec / 1000);
 411                 else if (usec < MAX_UDELAY_MS * 1000)
 412                         udelay(usec);
 413                 else
 414                         mdelay(usec / 1000);
 415
 416                 if (retries < 22)
 417                         usec *= 2;
 418         }
 419         return ret;
 420 }
 421
 422 /*
 423  * vmbus_set_event - Send an event notification to the parent
 424  */
 425 void vmbus_set_event(struct vmbus_channel *channel)
 426 {
 427         u32 child_relid = channel->offermsg.child_relid;
 428
 429         if (!channel->is_dedicated_interrupt)
 430                 vmbus_send_interrupt(child_relid);
 431
 432         hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 433 }
 434 EXPORT_SYMBOL_GPL(vmbus_set_event);