drivers/hv/hv_snapshot.c

   1 /*
   2  * An implementation of host initiated guest snapshot.
   3  *
   4  *
   5  * Copyright (C) 2013, Microsoft, Inc.
   6  * Author : K. Y. Srinivasan <kys@microsoft.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License version 2 as published
  10  * by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  15  * NON INFRINGEMENT.  See the GNU General Public License for more
  16  * details.
  17  *
  18  */
  19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/net.h>
  22 #include <linux/nls.h>
  23 #include <linux/connector.h>
  24 #include <linux/workqueue.h>
  25 #include <linux/hyperv.h>
  26
  27 #include "hyperv_vmbus.h"
  28 #include "hv_utils_transport.h"
  29
  30 #define VSS_MAJOR  5
  31 #define VSS_MINOR  0
  32 #define VSS_VERSION    (VSS_MAJOR << 16 | VSS_MINOR)
  33
  34 #define VSS_VER_COUNT 1
  35 static const int vss_versions[] = {
  36         VSS_VERSION
  37 };
  38
  39 #define FW_VER_COUNT 1
  40 static const int fw_versions[] = {
  41         UTIL_FW_VERSION
  42 };
  43
  44 /*
  45  * Timeout values are based on expecations from host
  46  */
  47 #define VSS_FREEZE_TIMEOUT (15 * 60)
  48
  49 /*
  50  * Global state maintained for transaction that is being processed. For a class
  51  * of integration services, including the "VSS service", the specified protocol
  52  * is a "request/response" protocol which means that there can only be single
  53  * outstanding transaction from the host at any given point in time. We use
  54  * this to simplify memory management in this driver - we cache and process
  55  * only one message at a time.
  56  *
  57  * While the request/response protocol is guaranteed by the host, we further
  58  * ensure this by serializing packet processing in this driver - we do not
  59  * read additional packets from the VMBUs until the current packet is fully
  60  * handled.
  61  */
  62
  63 static struct {
  64         int state;   /* hvutil_device_state */
  65         int recv_len; /* number of bytes received. */
  66         struct vmbus_channel *recv_channel; /* chn we got the request */
  67         u64 recv_req_id; /* request ID. */
  68         struct hv_vss_msg  *msg; /* current message */
  69 } vss_transaction;
  70
  71
  72 static void vss_respond_to_host(int error);
  73
  74 /*
  75  * This state maintains the version number registered by the daemon.
  76  */
  77 static int dm_reg_value;
  78
  79 static const char vss_devname[] = "vmbus/hv_vss";
  80 static __u8 *recv_buffer;
  81 static struct hvutil_transport *hvt;
  82
  83 static void vss_timeout_func(struct work_struct *dummy);
  84 static void vss_handle_request(struct work_struct *dummy);
  85
  86 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
  87 static DECLARE_WORK(vss_handle_request_work, vss_handle_request);
  88
  89 static void vss_poll_wrapper(void *channel)
  90 {
  91         /* Transaction is finished, reset the state here to avoid races. */
  92         vss_transaction.state = HVUTIL_READY;
  93         hv_vss_onchannelcallback(channel);
  94 }
  95
  96 /*
  97  * Callback when data is received from user mode.
  98  */
  99
 100 static void vss_timeout_func(struct work_struct *dummy)
 101 {
 102         /*
 103          * Timeout waiting for userspace component to reply happened.
 104          */
 105         pr_warn("VSS: timeout waiting for daemon to reply\n");
 106         vss_respond_to_host(HV_E_FAIL);
 107
 108         hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
 109 }
 110
 111 static void vss_register_done(void)
 112 {
 113         hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
 114         pr_debug("VSS: userspace daemon registered\n");
 115 }
 116
 117 static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
 118 {
 119         u32 our_ver = VSS_OP_REGISTER1;
 120
 121         switch (vss_msg->vss_hdr.operation) {
 122         case VSS_OP_REGISTER:
 123                 /* Daemon doesn't expect us to reply */
 124                 dm_reg_value = VSS_OP_REGISTER;
 125                 break;
 126         case VSS_OP_REGISTER1:
 127                 /* Daemon expects us to reply with our own version */
 128                 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
 129                                           vss_register_done))
 130                         return -EFAULT;
 131                 dm_reg_value = VSS_OP_REGISTER1;
 132                 break;
 133         default:
 134                 return -EINVAL;
 135         }
 136         pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value);
 137         return 0;
 138 }
 139
 140 static int vss_on_msg(void *msg, int len)
 141 {
 142         struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;
 143
 144         if (len != sizeof(*vss_msg)) {
 145                 pr_debug("VSS: Message size does not match length\n");
 146                 return -EINVAL;
 147         }
 148
 149         if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||
 150             vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
 151                 /*
 152                  * Don't process registration messages if we're in the middle
 153                  * of a transaction processing.
 154                  */
 155                 if (vss_transaction.state > HVUTIL_READY) {
 156                         pr_debug("VSS: Got unexpected registration request\n");
 157                         return -EINVAL;
 158                 }
 159
 160                 return vss_handle_handshake(vss_msg);
 161         } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
 162                 vss_transaction.state = HVUTIL_USERSPACE_RECV;
 163
 164                 if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)
 165                         vss_transaction.msg->vss_cf.flags =
 166                                 VSS_HBU_NO_AUTO_RECOVERY;
 167
 168                 if (cancel_delayed_work_sync(&vss_timeout_work)) {
 169                         vss_respond_to_host(vss_msg->error);
 170                         /* Transaction is finished, reset the state. */
 171                         hv_poll_channel(vss_transaction.recv_channel,
 172                                         vss_poll_wrapper);
 173                 }
 174         } else {
 175                 /* This is a spurious call! */
 176                 pr_debug("VSS: Transaction not active\n");
 177                 return -EINVAL;
 178         }
 179         return 0;
 180 }
 181
 182 static void vss_send_op(void)
 183 {
 184         int op = vss_transaction.msg->vss_hdr.operation;
 185         int rc;
 186         struct hv_vss_msg *vss_msg;
 187
 188         /* The transaction state is wrong. */
 189         if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) {
 190                 pr_debug("VSS: Unexpected attempt to send to daemon\n");
 191                 return;
 192         }
 193
 194         vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
 195         if (!vss_msg)
 196                 return;
 197
 198         vss_msg->vss_hdr.operation = op;
 199
 200         vss_transaction.state = HVUTIL_USERSPACE_REQ;
 201
 202         schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ?
 203                         VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ);
 204
 205         rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
 206         if (rc) {
 207                 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
 208                 if (cancel_delayed_work_sync(&vss_timeout_work)) {
 209                         vss_respond_to_host(HV_E_FAIL);
 210                         vss_transaction.state = HVUTIL_READY;
 211                 }
 212         }
 213
 214         kfree(vss_msg);
 215 }
 216
 217 static void vss_handle_request(struct work_struct *dummy)
 218 {
 219         switch (vss_transaction.msg->vss_hdr.operation) {
 220         /*
 221          * Initiate a "freeze/thaw" operation in the guest.
 222          * We respond to the host once the operation is complete.
 223          *
 224          * We send the message to the user space daemon and the operation is
 225          * performed in the daemon.
 226          */
 227         case VSS_OP_THAW:
 228         case VSS_OP_FREEZE:
 229         case VSS_OP_HOT_BACKUP:
 230                 if (vss_transaction.state < HVUTIL_READY) {
 231                         /* Userspace is not registered yet */
 232                         pr_debug("VSS: Not ready for request.\n");
 233                         vss_respond_to_host(HV_E_FAIL);
 234                         return;
 235                 }
 236
 237                 pr_debug("VSS: Received request for op code: %d\n",
 238                         vss_transaction.msg->vss_hdr.operation);
 239                 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
 240                 vss_send_op();
 241                 return;
 242         case VSS_OP_GET_DM_INFO:
 243                 vss_transaction.msg->dm_info.flags = 0;
 244                 break;
 245         default:
 246                 break;
 247         }
 248
 249         vss_respond_to_host(0);
 250         hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
 251 }
 252
 253 /*
 254  * Send a response back to the host.
 255  */
 256
 257 static void
 258 vss_respond_to_host(int error)
 259 {
 260         struct icmsg_hdr *icmsghdrp;
 261         u32     buf_len;
 262         struct vmbus_channel *channel;
 263         u64     req_id;
 264
 265         /*
 266          * Copy the global state for completing the transaction. Note that
 267          * only one transaction can be active at a time.
 268          */
 269
 270         buf_len = vss_transaction.recv_len;
 271         channel = vss_transaction.recv_channel;
 272         req_id = vss_transaction.recv_req_id;
 273
 274         icmsghdrp = (struct icmsg_hdr *)
 275                         &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 276
 277         if (channel->onchannel_callback == NULL)
 278                 /*
 279                  * We have raced with util driver being unloaded;
 280                  * silently return.
 281                  */
 282                 return;
 283
 284         icmsghdrp->status = error;
 285
 286         icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 287
 288         vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 289                                 VM_PKT_DATA_INBAND, 0);
 290
 291 }
 292
 293 /*
 294  * This callback is invoked when we get a VSS message from the host.
 295  * The host ensures that only one VSS transaction can be active at a time.
 296  */
 297
 298 void hv_vss_onchannelcallback(void *context)
 299 {
 300         struct vmbus_channel *channel = context;
 301         u32 recvlen;
 302         u64 requestid;
 303         struct hv_vss_msg *vss_msg;
 304         int vss_srv_version;
 305
 306         struct icmsg_hdr *icmsghdrp;
 307
 308         if (vss_transaction.state > HVUTIL_READY)
 309                 return;
 310
 311         vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
 312                          &requestid);
 313
 314         if (recvlen > 0) {
 315                 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
 316                         sizeof(struct vmbuspipe_hdr)];
 317
 318                 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 319                         if (vmbus_prep_negotiate_resp(icmsghdrp,
 320                                  recv_buffer, fw_versions, FW_VER_COUNT,
 321                                  vss_versions, VSS_VER_COUNT,
 322                                  NULL, &vss_srv_version)) {
 323
 324                                 pr_info("VSS IC version %d.%d\n",
 325                                         vss_srv_version >> 16,
 326                                         vss_srv_version & 0xFFFF);
 327                         }
 328                 } else {
 329                         vss_msg = (struct hv_vss_msg *)&recv_buffer[
 330                                 sizeof(struct vmbuspipe_hdr) +
 331                                 sizeof(struct icmsg_hdr)];
 332
 333                         /*
 334                          * Stash away this global state for completing the
 335                          * transaction; note transactions are serialized.
 336                          */
 337
 338                         vss_transaction.recv_len = recvlen;
 339                         vss_transaction.recv_req_id = requestid;
 340                         vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
 341
 342                         schedule_work(&vss_handle_request_work);
 343                         return;
 344                 }
 345
 346                 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
 347                         | ICMSGHDRFLAG_RESPONSE;
 348
 349                 vmbus_sendpacket(channel, recv_buffer,
 350                                        recvlen, requestid,
 351                                        VM_PKT_DATA_INBAND, 0);
 352         }
 353
 354 }
 355
 356 static void vss_on_reset(void)
 357 {
 358         if (cancel_delayed_work_sync(&vss_timeout_work))
 359                 vss_respond_to_host(HV_E_FAIL);
 360         vss_transaction.state = HVUTIL_DEVICE_INIT;
 361 }
 362
 363 int
 364 hv_vss_init(struct hv_util_service *srv)
 365 {
 366         if (vmbus_proto_version < VERSION_WIN8_1) {
 367                 pr_warn("Integration service 'Backup (volume snapshot)'"
 368                         " not supported on this host version.\n");
 369                 return -ENOTSUPP;
 370         }
 371         recv_buffer = srv->recv_buffer;
 372         vss_transaction.recv_channel = srv->channel;
 373
 374         /*
 375          * When this driver loads, the user level daemon that
 376          * processes the host requests may not yet be running.
 377          * Defer processing channel callbacks until the daemon
 378          * has registered.
 379          */
 380         vss_transaction.state = HVUTIL_DEVICE_INIT;
 381
 382         hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
 383                                     vss_on_msg, vss_on_reset);
 384         if (!hvt) {
 385                 pr_warn("VSS: Failed to initialize transport\n");
 386                 return -EFAULT;
 387         }
 388
 389         return 0;
 390 }
 391
 392 void hv_vss_deinit(void)
 393 {
 394         vss_transaction.state = HVUTIL_DEVICE_DYING;
 395         cancel_delayed_work_sync(&vss_timeout_work);
 396         cancel_work_sync(&vss_handle_request_work);
 397         hvutil_transport_destroy(hvt);
 398 }