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 static struct completion release_event;
  83
  84 static void vss_timeout_func(struct work_struct *dummy);
  85 static void vss_handle_request(struct work_struct *dummy);
  86
  87 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
  88 static DECLARE_WORK(vss_handle_request_work, vss_handle_request);
  89
  90 static void vss_poll_wrapper(void *channel)
  91 {
  92         /* Transaction is finished, reset the state here to avoid races. */
  93         vss_transaction.state = HVUTIL_READY;
  94         hv_vss_onchannelcallback(channel);
  95 }
  96
  97 /*
  98  * Callback when data is received from user mode.
  99  */
 100
 101 static void vss_timeout_func(struct work_struct *dummy)
 102 {
 103         /*
 104          * Timeout waiting for userspace component to reply happened.
 105          */
 106         pr_warn("VSS: timeout waiting for daemon to reply\n");
 107         vss_respond_to_host(HV_E_FAIL);
 108
 109         hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
 110 }
 111
 112 static void vss_register_done(void)
 113 {
 114         hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
 115         pr_debug("VSS: userspace daemon registered\n");
 116 }
 117
 118 static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
 119 {
 120         u32 our_ver = VSS_OP_REGISTER1;
 121
 122         switch (vss_msg->vss_hdr.operation) {
 123         case VSS_OP_REGISTER:
 124                 /* Daemon doesn't expect us to reply */
 125                 dm_reg_value = VSS_OP_REGISTER;
 126                 break;
 127         case VSS_OP_REGISTER1:
 128                 /* Daemon expects us to reply with our own version */
 129                 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
 130                                           vss_register_done))
 131                         return -EFAULT;
 132                 dm_reg_value = VSS_OP_REGISTER1;
 133                 break;
 134         default:
 135                 return -EINVAL;
 136         }
 137         pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value);
 138         return 0;
 139 }
 140
 141 static int vss_on_msg(void *msg, int len)
 142 {
 143         struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;
 144
 145         if (len != sizeof(*vss_msg)) {
 146                 pr_debug("VSS: Message size does not match length\n");
 147                 return -EINVAL;
 148         }
 149
 150         if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||
 151             vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
 152                 /*
 153                  * Don't process registration messages if we're in the middle
 154                  * of a transaction processing.
 155                  */
 156                 if (vss_transaction.state > HVUTIL_READY) {
 157                         pr_debug("VSS: Got unexpected registration request\n");
 158                         return -EINVAL;
 159                 }
 160
 161                 return vss_handle_handshake(vss_msg);
 162         } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
 163                 vss_transaction.state = HVUTIL_USERSPACE_RECV;
 164
 165                 if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)
 166                         vss_transaction.msg->vss_cf.flags =
 167                                 VSS_HBU_NO_AUTO_RECOVERY;
 168
 169                 if (cancel_delayed_work_sync(&vss_timeout_work)) {
 170                         vss_respond_to_host(vss_msg->error);
 171                         /* Transaction is finished, reset the state. */
 172                         hv_poll_channel(vss_transaction.recv_channel,
 173                                         vss_poll_wrapper);
 174                 }
 175         } else {
 176                 /* This is a spurious call! */
 177                 pr_debug("VSS: Transaction not active\n");
 178                 return -EINVAL;
 179         }
 180         return 0;
 181 }
 182
 183 static void vss_send_op(void)
 184 {
 185         int op = vss_transaction.msg->vss_hdr.operation;
 186         int rc;
 187         struct hv_vss_msg *vss_msg;
 188
 189         /* The transaction state is wrong. */
 190         if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) {
 191                 pr_debug("VSS: Unexpected attempt to send to daemon\n");
 192                 return;
 193         }
 194
 195         vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
 196         if (!vss_msg)
 197                 return;
 198
 199         vss_msg->vss_hdr.operation = op;
 200
 201         vss_transaction.state = HVUTIL_USERSPACE_REQ;
 202
 203         schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ?
 204                         VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ);
 205
 206         rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
 207         if (rc) {
 208                 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
 209                 if (cancel_delayed_work_sync(&vss_timeout_work)) {
 210                         vss_respond_to_host(HV_E_FAIL);
 211                         vss_transaction.state = HVUTIL_READY;
 212                 }
 213         }
 214
 215         kfree(vss_msg);
 216
 217         return;
 218 }
 219
 220 static void vss_handle_request(struct work_struct *dummy)
 221 {
 222         switch (vss_transaction.msg->vss_hdr.operation) {
 223         /*
 224          * Initiate a "freeze/thaw" operation in the guest.
 225          * We respond to the host once the operation is complete.
 226          *
 227          * We send the message to the user space daemon and the operation is
 228          * performed in the daemon.
 229          */
 230         case VSS_OP_THAW:
 231         case VSS_OP_FREEZE:
 232         case VSS_OP_HOT_BACKUP:
 233                 if (vss_transaction.state < HVUTIL_READY) {
 234                         /* Userspace is not registered yet */
 235                         pr_debug("VSS: Not ready for request.\n");
 236                         vss_respond_to_host(HV_E_FAIL);
 237                         return;
 238                 }
 239
 240                 pr_debug("VSS: Received request for op code: %d\n",
 241                         vss_transaction.msg->vss_hdr.operation);
 242                 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
 243                 vss_send_op();
 244                 return;
 245         case VSS_OP_GET_DM_INFO:
 246                 vss_transaction.msg->dm_info.flags = 0;
 247                 break;
 248         default:
 249                 break;
 250         }
 251
 252         vss_respond_to_host(0);
 253         hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
 254 }
 255
 256 /*
 257  * Send a response back to the host.
 258  */
 259
 260 static void
 261 vss_respond_to_host(int error)
 262 {
 263         struct icmsg_hdr *icmsghdrp;
 264         u32     buf_len;
 265         struct vmbus_channel *channel;
 266         u64     req_id;
 267
 268         /*
 269          * Copy the global state for completing the transaction. Note that
 270          * only one transaction can be active at a time.
 271          */
 272
 273         buf_len = vss_transaction.recv_len;
 274         channel = vss_transaction.recv_channel;
 275         req_id = vss_transaction.recv_req_id;
 276
 277         icmsghdrp = (struct icmsg_hdr *)
 278                         &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 279
 280         if (channel->onchannel_callback == NULL)
 281                 /*
 282                  * We have raced with util driver being unloaded;
 283                  * silently return.
 284                  */
 285                 return;
 286
 287         icmsghdrp->status = error;
 288
 289         icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 290
 291         vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 292                                 VM_PKT_DATA_INBAND, 0);
 293
 294 }
 295
 296 /*
 297  * This callback is invoked when we get a VSS message from the host.
 298  * The host ensures that only one VSS transaction can be active at a time.
 299  */
 300
 301 void hv_vss_onchannelcallback(void *context)
 302 {
 303         struct vmbus_channel *channel = context;
 304         u32 recvlen;
 305         u64 requestid;
 306         struct hv_vss_msg *vss_msg;
 307         int vss_srv_version;
 308
 309         struct icmsg_hdr *icmsghdrp;
 310
 311         if (vss_transaction.state > HVUTIL_READY)
 312                 return;
 313
 314         vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
 315                          &requestid);
 316
 317         if (recvlen > 0) {
 318                 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
 319                         sizeof(struct vmbuspipe_hdr)];
 320
 321                 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 322                         if (vmbus_prep_negotiate_resp(icmsghdrp,
 323                                  recv_buffer, fw_versions, FW_VER_COUNT,
 324                                  vss_versions, VSS_VER_COUNT,
 325                                  NULL, &vss_srv_version)) {
 326
 327                                 pr_info("VSS IC version %d.%d\n",
 328                                         vss_srv_version >> 16,
 329                                         vss_srv_version & 0xFFFF);
 330                         }
 331                 } else {
 332                         vss_msg = (struct hv_vss_msg *)&recv_buffer[
 333                                 sizeof(struct vmbuspipe_hdr) +
 334                                 sizeof(struct icmsg_hdr)];
 335
 336                         /*
 337                          * Stash away this global state for completing the
 338                          * transaction; note transactions are serialized.
 339                          */
 340
 341                         vss_transaction.recv_len = recvlen;
 342                         vss_transaction.recv_req_id = requestid;
 343                         vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
 344
 345                         schedule_work(&vss_handle_request_work);
 346                         return;
 347                 }
 348
 349                 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
 350                         | ICMSGHDRFLAG_RESPONSE;
 351
 352                 vmbus_sendpacket(channel, recv_buffer,
 353                                        recvlen, requestid,
 354                                        VM_PKT_DATA_INBAND, 0);
 355         }
 356
 357 }
 358
 359 static void vss_on_reset(void)
 360 {
 361         if (cancel_delayed_work_sync(&vss_timeout_work))
 362                 vss_respond_to_host(HV_E_FAIL);
 363         vss_transaction.state = HVUTIL_DEVICE_INIT;
 364         complete(&release_event);
 365 }
 366
 367 int
 368 hv_vss_init(struct hv_util_service *srv)
 369 {
 370         init_completion(&release_event);
 371         if (vmbus_proto_version < VERSION_WIN8_1) {
 372                 pr_warn("Integration service 'Backup (volume snapshot)'"
 373                         " not supported on this host version.\n");
 374                 return -ENOTSUPP;
 375         }
 376         recv_buffer = srv->recv_buffer;
 377         vss_transaction.recv_channel = srv->channel;
 378
 379         /*
 380          * When this driver loads, the user level daemon that
 381          * processes the host requests may not yet be running.
 382          * Defer processing channel callbacks until the daemon
 383          * has registered.
 384          */
 385         vss_transaction.state = HVUTIL_DEVICE_INIT;
 386
 387         hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
 388                                     vss_on_msg, vss_on_reset);
 389         if (!hvt) {
 390                 pr_warn("VSS: Failed to initialize transport\n");
 391                 return -EFAULT;
 392         }
 393
 394         return 0;
 395 }
 396
 397 void hv_vss_deinit(void)
 398 {
 399         vss_transaction.state = HVUTIL_DEVICE_DYING;
 400         cancel_delayed_work_sync(&vss_timeout_work);
 401         cancel_work_sync(&vss_handle_request_work);
 402         hvutil_transport_destroy(hvt);
 403         wait_for_completion(&release_event);
 404 }