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
  43 /*
  44  * Negotiated protocol version with the host.
  45  */
  46 __u32 vmbus_proto_version;
  47 EXPORT_SYMBOL_GPL(vmbus_proto_version);
  48
  49 static __u32 vmbus_get_next_version(__u32 current_version)
  50 {
  51         switch (current_version) {
  52         case (VERSION_WIN7):
  53                 return VERSION_WS2008;
  54
  55         case (VERSION_WIN8):
  56                 return VERSION_WIN7;
  57
  58         case (VERSION_WS2008):
  59         default:
  60                 return VERSION_INVAL;
  61         }
  62 }
  63
  64 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
  65                                         __u32 version)
  66 {
  67         int ret = 0;
  68         struct vmbus_channel_initiate_contact *msg;
  69         unsigned long flags;
  70
  71         init_completion(&msginfo->waitevent);
  72
  73         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
  74
  75         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
  76         msg->vmbus_version_requested = version;
  77         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
  78         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages);
  79         msg->monitor_page2 = virt_to_phys(
  80                         (void *)((unsigned long)vmbus_connection.monitor_pages +
  81                                  PAGE_SIZE));
  82
  83         /*
  84          * Add to list before we send the request since we may
  85          * receive the response before returning from this routine
  86          */
  87         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
  88         list_add_tail(&msginfo->msglistentry,
  89                       &vmbus_connection.chn_msg_list);
  90
  91         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
  92
  93         ret = vmbus_post_msg(msg,
  94                                sizeof(struct vmbus_channel_initiate_contact));
  95         if (ret != 0) {
  96                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
  97                 list_del(&msginfo->msglistentry);
  98                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
  99                                         flags);
 100                 return ret;
 101         }
 102
 103         /* Wait for the connection response */
 104         wait_for_completion(&msginfo->waitevent);
 105
 106         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 107         list_del(&msginfo->msglistentry);
 108         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 109
 110         /* Check if successful */
 111         if (msginfo->response.version_response.version_supported) {
 112                 vmbus_connection.conn_state = CONNECTED;
 113         } else {
 114                 return -ECONNREFUSED;
 115         }
 116
 117         return ret;
 118 }
 119
 120 /*
 121  * vmbus_connect - Sends a connect request on the partition service connection
 122  */
 123 int vmbus_connect(void)
 124 {
 125         int ret = 0;
 126         struct vmbus_channel_msginfo *msginfo = NULL;
 127         __u32 version;
 128
 129         /* Initialize the vmbus connection */
 130         vmbus_connection.conn_state = CONNECTING;
 131         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
 132         if (!vmbus_connection.work_queue) {
 133                 ret = -ENOMEM;
 134                 goto cleanup;
 135         }
 136
 137         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
 138         spin_lock_init(&vmbus_connection.channelmsg_lock);
 139
 140         INIT_LIST_HEAD(&vmbus_connection.chn_list);
 141         spin_lock_init(&vmbus_connection.channel_lock);
 142
 143         /*
 144          * Setup the vmbus event connection for channel interrupt
 145          * abstraction stuff
 146          */
 147         vmbus_connection.int_page =
 148         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 149         if (vmbus_connection.int_page == NULL) {
 150                 ret = -ENOMEM;
 151                 goto cleanup;
 152         }
 153
 154         vmbus_connection.recv_int_page = vmbus_connection.int_page;
 155         vmbus_connection.send_int_page =
 156                 (void *)((unsigned long)vmbus_connection.int_page +
 157                         (PAGE_SIZE >> 1));
 158
 159         /*
 160          * Setup the monitor notification facility. The 1st page for
 161          * parent->child and the 2nd page for child->parent
 162          */
 163         vmbus_connection.monitor_pages =
 164         (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 1);
 165         if (vmbus_connection.monitor_pages == NULL) {
 166                 ret = -ENOMEM;
 167                 goto cleanup;
 168         }
 169
 170         msginfo = kzalloc(sizeof(*msginfo) +
 171                           sizeof(struct vmbus_channel_initiate_contact),
 172                           GFP_KERNEL);
 173         if (msginfo == NULL) {
 174                 ret = -ENOMEM;
 175                 goto cleanup;
 176         }
 177
 178         /*
 179          * Negotiate a compatible VMBUS version number with the
 180          * host. We start with the highest number we can support
 181          * and work our way down until we negotiate a compatible
 182          * version.
 183          */
 184
 185         version = VERSION_CURRENT;
 186
 187         do {
 188                 ret = vmbus_negotiate_version(msginfo, version);
 189                 if (ret == 0)
 190                         break;
 191
 192                 version = vmbus_get_next_version(version);
 193         } while (version != VERSION_INVAL);
 194
 195         if (version == VERSION_INVAL)
 196                 goto cleanup;
 197
 198         vmbus_proto_version = version;
 199         pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
 200                     host_info_eax, host_info_ebx >> 16,
 201                     host_info_ebx & 0xFFFF, host_info_ecx,
 202                     host_info_edx >> 24, host_info_edx & 0xFFFFFF,
 203                     version >> 16, version & 0xFFFF);
 204
 205         kfree(msginfo);
 206         return 0;
 207
 208 cleanup:
 209         pr_err("Unable to connect to host\n");
 210         vmbus_connection.conn_state = DISCONNECTED;
 211
 212         if (vmbus_connection.work_queue)
 213                 destroy_workqueue(vmbus_connection.work_queue);
 214
 215         if (vmbus_connection.int_page) {
 216                 free_pages((unsigned long)vmbus_connection.int_page, 0);
 217                 vmbus_connection.int_page = NULL;
 218         }
 219
 220         if (vmbus_connection.monitor_pages) {
 221                 free_pages((unsigned long)vmbus_connection.monitor_pages, 1);
 222                 vmbus_connection.monitor_pages = NULL;
 223         }
 224
 225         kfree(msginfo);
 226
 227         return ret;
 228 }
 229
 230
 231 /*
 232  * relid2channel - Get the channel object given its
 233  * child relative id (ie channel id)
 234  */
 235 struct vmbus_channel *relid2channel(u32 relid)
 236 {
 237         struct vmbus_channel *channel;
 238         struct vmbus_channel *found_channel  = NULL;
 239         unsigned long flags;
 240
 241         spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 242         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 243                 if (channel->offermsg.child_relid == relid) {
 244                         found_channel = channel;
 245                         break;
 246                 }
 247         }
 248         spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 249
 250         return found_channel;
 251 }
 252
 253 /*
 254  * process_chn_event - Process a channel event notification
 255  */
 256 static void process_chn_event(u32 relid)
 257 {
 258         struct vmbus_channel *channel;
 259         unsigned long flags;
 260         void *arg;
 261         bool read_state;
 262         u32 bytes_to_read;
 263
 264         /*
 265          * Find the channel based on this relid and invokes the
 266          * channel callback to process the event
 267          */
 268         channel = relid2channel(relid);
 269
 270         if (!channel) {
 271                 pr_err("channel not found for relid - %u\n", relid);
 272                 return;
 273         }
 274
 275         /*
 276          * A channel once created is persistent even when there
 277          * is no driver handling the device. An unloading driver
 278          * sets the onchannel_callback to NULL under the
 279          * protection of the channel inbound_lock. Thus, checking
 280          * and invoking the driver specific callback takes care of
 281          * orderly unloading of the driver.
 282          */
 283
 284         spin_lock_irqsave(&channel->inbound_lock, flags);
 285         if (channel->onchannel_callback != NULL) {
 286                 arg = channel->channel_callback_context;
 287                 read_state = channel->batched_reading;
 288                 /*
 289                  * This callback reads the messages sent by the host.
 290                  * We can optimize host to guest signaling by ensuring:
 291                  * 1. While reading the channel, we disable interrupts from
 292                  *    host.
 293                  * 2. Ensure that we process all posted messages from the host
 294                  *    before returning from this callback.
 295                  * 3. Once we return, enable signaling from the host. Once this
 296                  *    state is set we check to see if additional packets are
 297                  *    available to read. In this case we repeat the process.
 298                  */
 299
 300                 do {
 301                         hv_begin_read(&channel->inbound);
 302                         channel->onchannel_callback(arg);
 303                         bytes_to_read = hv_end_read(&channel->inbound);
 304                 } while (read_state && (bytes_to_read != 0));
 305         } else {
 306                 pr_err("no channel callback for relid - %u\n", relid);
 307         }
 308
 309         spin_unlock_irqrestore(&channel->inbound_lock, flags);
 310 }
 311
 312 /*
 313  * vmbus_on_event - Handler for events
 314  */
 315 void vmbus_on_event(unsigned long data)
 316 {
 317         u32 dword;
 318         u32 maxdword;
 319         int bit;
 320         u32 relid;
 321         u32 *recv_int_page = NULL;
 322         void *page_addr;
 323         int cpu = smp_processor_id();
 324         union hv_synic_event_flags *event;
 325
 326         if ((vmbus_proto_version == VERSION_WS2008) ||
 327                 (vmbus_proto_version == VERSION_WIN7)) {
 328                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
 329                 recv_int_page = vmbus_connection.recv_int_page;
 330         } else {
 331                 /*
 332                  * When the host is win8 and beyond, the event page
 333                  * can be directly checked to get the id of the channel
 334                  * that has the interrupt pending.
 335                  */
 336                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
 337                 page_addr = hv_context.synic_event_page[cpu];
 338                 event = (union hv_synic_event_flags *)page_addr +
 339                                                  VMBUS_MESSAGE_SINT;
 340                 recv_int_page = event->flags32;
 341         }
 342
 343
 344
 345         /* Check events */
 346         if (!recv_int_page)
 347                 return;
 348         for (dword = 0; dword < maxdword; dword++) {
 349                 if (!recv_int_page[dword])
 350                         continue;
 351                 for (bit = 0; bit < 32; bit++) {
 352                         if (sync_test_and_clear_bit(bit,
 353                                 (unsigned long *)&recv_int_page[dword])) {
 354                                 relid = (dword << 5) + bit;
 355
 356                                 if (relid == 0)
 357                                         /*
 358                                          * Special case - vmbus
 359                                          * channel protocol msg
 360                                          */
 361                                         continue;
 362
 363                                 process_chn_event(relid);
 364                         }
 365                 }
 366         }
 367 }
 368
 369 /*
 370  * vmbus_post_msg - Send a msg on the vmbus's message connection
 371  */
 372 int vmbus_post_msg(void *buffer, size_t buflen)
 373 {
 374         union hv_connection_id conn_id;
 375         int ret = 0;
 376         int retries = 0;
 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 < 3) {
 387                 ret =  hv_post_message(conn_id, 1, buffer, buflen);
 388                 if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
 389                         return ret;
 390                 retries++;
 391                 msleep(100);
 392         }
 393         return ret;
 394 }
 395
 396 /*
 397  * vmbus_set_event - Send an event notification to the parent
 398  */
 399 int vmbus_set_event(struct vmbus_channel *channel)
 400 {
 401         u32 child_relid = channel->offermsg.child_relid;
 402
 403         if (!channel->is_dedicated_interrupt) {
 404                 /* Each u32 represents 32 channels */
 405                 sync_set_bit(child_relid & 31,
 406                         (unsigned long *)vmbus_connection.send_int_page +
 407                         (child_relid >> 5));
 408         }
 409
 410         return hv_signal_event(channel->sig_event);
 411 }