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