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/mshyperv.h>
  35
  36 #include "hyperv_vmbus.h"
  37
  38
  39 struct vmbus_connection vmbus_connection = {
  40         .conn_state             = DISCONNECTED,
  41         .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),
  42 };
  43 EXPORT_SYMBOL_GPL(vmbus_connection);
  44
  45 /*
  46  * Negotiated protocol version with the host.
  47  */
  48 __u32 vmbus_proto_version;
  49 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  50
  51 static __u32 vmbus_get_next_version(__u32 current_version)
  52 {
  53         switch (current_version) {
  54         case (VERSION_WIN7):
  55                 return VERSION_WS2008;
  56
  57         case (VERSION_WIN8):
  58                 return VERSION_WIN7;
  59
  60         case (VERSION_WIN8_1):
  61                 return VERSION_WIN8;
  62
  63         case (VERSION_WIN10):
  64                 return VERSION_WIN8_1;
  65
  66         case (VERSION_WS2008):
  67         default:
  68                 return VERSION_INVAL;
  69         }
  70 }
  71
  72 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  73                                         __u32 version)
  74 {
  75         int ret = 0;
  76         struct vmbus_channel_initiate_contact *msg;
  77         unsigned long flags;
  78
  79         init_completion(&msginfo->waitevent);
  80
  81         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  82
  83         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  84         msg->vmbus_version_requested = version;
  85         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  86         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
  87         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
  88         /*
  89          * We want all channel messages to be delivered on CPU 0.
  90          * This has been the behavior pre-win8. This is not
  91          * perf issue and having all channel messages delivered on CPU 0
  92          * would be ok.
  93          * For post win8 hosts, we support receiving channel messagges on
  94          * all the CPUs. This is needed for kexec to work correctly where
  95          * the CPU attempting to connect may not be CPU 0.
  96          */
  97         if (version >= VERSION_WIN8_1) {
  98                 msg->target_vcpu =
  99                         hv_cpu_number_to_vp_number(smp_processor_id());
 100                 vmbus_connection.connect_cpu = smp_processor_id();
 101         } else {
 102                 msg->target_vcpu = 0;
 103                 vmbus_connection.connect_cpu = 0;
 104         }
 105
 106         /*
 107          * Add to list before we send the request since we may
 108          * receive the response before returning from this routine
 109          */
 110         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 111         list_add_tail(&msginfo->msglistentry,
 112                       &vmbus_connection.chn_msg_list);
 113
 114         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 115
 116         ret = vmbus_post_msg(msg,
 117                              sizeof(struct vmbus_channel_initiate_contact),
 118                              true);
 119
 120         trace_vmbus_negotiate_version(msg, ret);
 121
 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         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 165         spin_lock_init(&vmbus_connection.channelmsg_lock);
 166
 167         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 168         mutex_init(&vmbus_connection.channel_mutex);
 169
 170         /*
 171          * Setup the vmbus event connection for channel interrupt
 172          * abstraction stuff
 173          */
 174         vmbus_connection.int_page =
 175         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 176         if (vmbus_connection.int_page == NULL) {
 177                 ret = -ENOMEM;
 178                 goto cleanup;
 179         }
 180
 181         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 182         vmbus_connection.send_int_page =
 183                 (void *)((unsigned long)vmbus_connection.int_page +
 184                         (PAGE_SIZE >> 1));
 185
 186         /*
 187          * Setup the monitor notification facility. The 1st page for
 188          * parent->child and the 2nd page for child->parent
 189          */
 190         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 191         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
 192         if ((vmbus_connection.monitor_pages[0] == NULL) ||
 193             (vmbus_connection.monitor_pages[1] == NULL)) {
 194                 ret = -ENOMEM;
 195                 goto cleanup;
 196         }
 197
 198         msginfo = kzalloc(sizeof(*msginfo) +
 199                           sizeof(struct vmbus_channel_initiate_contact),
 200                           GFP_KERNEL);
 201         if (msginfo == NULL) {
 202                 ret = -ENOMEM;
 203                 goto cleanup;
 204         }
 205
 206         /*
 207          * Negotiate a compatible VMBUS version number with the
 208          * host. We start with the highest number we can support
 209          * and work our way down until we negotiate a compatible
 210          * version.
 211          */
 212
 213         version = VERSION_CURRENT;
 214
 215         do {
 216                 ret = vmbus_negotiate_version(msginfo, version);
 217                 if (ret == -ETIMEDOUT)
 218                         goto cleanup;
 219
 220                 if (vmbus_connection.conn_state == CONNECTED)
 221                         break;
 222
 223                 version = vmbus_get_next_version(version);
 224         } while (version != VERSION_INVAL);
 225
 226         if (version == VERSION_INVAL)
 227                 goto cleanup;
 228
 229         vmbus_proto_version = version;
 230         pr_info("Vmbus version:%d.%d\n",
 231                 version >> 16, version & 0xFFFF);
 232
 233         kfree(msginfo);
 234         return 0;
 235
 236 cleanup:
 237         pr_err("Unable to connect to host\n");
 238
 239         vmbus_connection.conn_state = DISCONNECTED;
 240         vmbus_disconnect();
 241
 242         kfree(msginfo);
 243
 244         return ret;
 245 }
 246
 247 void vmbus_disconnect(void)
 248 {
 249         /*
 250          * First send the unload request to the host.
 251          */
 252         vmbus_initiate_unload(false);
 253
 254         if (vmbus_connection.work_queue) {
 255                 drain_workqueue(vmbus_connection.work_queue);
 256                 destroy_workqueue(vmbus_connection.work_queue);
 257         }
 258
 259         if (vmbus_connection.int_page) {
 260                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 261                 vmbus_connection.int_page = NULL;
 262         }
 263
 264         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
 265         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
 266         vmbus_connection.monitor_pages[0] = NULL;
 267         vmbus_connection.monitor_pages[1] = NULL;
 268 }
 269
 270 /*
 271  * relid2channel - Get the channel object given its
 272  * child relative id (ie channel id)
 273  */
 274 struct vmbus_channel *relid2channel(u32 relid)
 275 {
 276         struct vmbus_channel *channel;
 277         struct vmbus_channel *found_channel  = NULL;
 278         struct list_head *cur, *tmp;
 279         struct vmbus_channel *cur_sc;
 280
 281         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 282
 283         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 284                 if (channel->offermsg.child_relid == relid) {
 285                         found_channel = channel;
 286                         break;
 287                 } else if (!list_empty(&channel->sc_list)) {
 288                         /*
 289                          * Deal with sub-channels.
 290                          */
 291                         list_for_each_safe(cur, tmp, &channel->sc_list) {
 292                                 cur_sc = list_entry(cur, struct vmbus_channel,
 293                                                         sc_list);
 294                                 if (cur_sc->offermsg.child_relid == relid) {
 295                                         found_channel = cur_sc;
 296                                         break;
 297                                 }
 298                         }
 299                 }
 300         }
 301
 302         return found_channel;
 303 }
 304
 305 /*
 306  * vmbus_on_event - Process a channel event notification
 307  *
 308  * For batched channels (default) optimize host to guest signaling
 309  * by ensuring:
 310  * 1. While reading the channel, we disable interrupts from host.
 311  * 2. Ensure that we process all posted messages from the host
 312  *    before returning from this callback.
 313  * 3. Once we return, enable signaling from the host. Once this
 314  *    state is set we check to see if additional packets are
 315  *    available to read. In this case we repeat the process.
 316  *    If this tasklet has been running for a long time
 317  *    then reschedule ourselves.
 318  */
 319 void vmbus_on_event(unsigned long data)
 320 {
 321         struct vmbus_channel *channel = (void *) data;
 322         unsigned long time_limit = jiffies + 2;
 323
 324         trace_vmbus_on_event(channel);
 325
 326         do {
 327                 void (*callback_fn)(void *);
 328
 329                 /* A channel once created is persistent even when
 330                  * there is no driver handling the device. An
 331                  * unloading driver sets the onchannel_callback to NULL.
 332                  */
 333                 callback_fn = READ_ONCE(channel->onchannel_callback);
 334                 if (unlikely(callback_fn == NULL))
 335                         return;
 336
 337                 (*callback_fn)(channel->channel_callback_context);
 338
 339                 if (channel->callback_mode != HV_CALL_BATCHED)
 340                         return;
 341
 342                 if (likely(hv_end_read(&channel->inbound) == 0))
 343                         return;
 344
 345                 hv_begin_read(&channel->inbound);
 346         } while (likely(time_before(jiffies, time_limit)));
 347
 348         /* The time limit (2 jiffies) has been reached */
 349         tasklet_schedule(&channel->callback_event);
 350 }
 351
 352 /*
 353  * vmbus_post_msg - Send a msg on the vmbus's message connection
 354  */
 355 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 356 {
 357         union hv_connection_id conn_id;
 358         int ret = 0;
 359         int retries = 0;
 360         u32 usec = 1;
 361
 362         conn_id.asu32 = 0;
 363         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
 364
 365         /*
 366          * hv_post_message() can have transient failures because of
 367          * insufficient resources. Retry the operation a couple of
 368          * times before giving up.
 369          */
 370         while (retries < 100) {
 371                 ret = hv_post_message(conn_id, 1, buffer, buflen);
 372
 373                 switch (ret) {
 374                 case HV_STATUS_INVALID_CONNECTION_ID:
 375                         /*
 376                          * We could get this if we send messages too
 377                          * frequently.
 378                          */
 379                         ret = -EAGAIN;
 380                         break;
 381                 case HV_STATUS_INSUFFICIENT_MEMORY:
 382                 case HV_STATUS_INSUFFICIENT_BUFFERS:
 383                         ret = -ENOBUFS;
 384                         break;
 385                 case HV_STATUS_SUCCESS:
 386                         return ret;
 387                 default:
 388                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
 389                         return -EINVAL;
 390                 }
 391
 392                 retries++;
 393                 if (can_sleep && usec > 1000)
 394                         msleep(usec / 1000);
 395                 else if (usec < MAX_UDELAY_MS * 1000)
 396                         udelay(usec);
 397                 else
 398                         mdelay(usec / 1000);
 399
 400                 if (retries < 22)
 401                         usec *= 2;
 402         }
 403         return ret;
 404 }
 405
 406 /*
 407  * vmbus_set_event - Send an event notification to the parent
 408  */
 409 void vmbus_set_event(struct vmbus_channel *channel)
 410 {
 411         u32 child_relid = channel->offermsg.child_relid;
 412
 413         if (!channel->is_dedicated_interrupt)
 414                 vmbus_send_interrupt(child_relid);
 415
 416         ++channel->sig_events;
 417
 418         hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
 419 }
 420 EXPORT_SYMBOL_GPL(vmbus_set_event);