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_USERSPACE_TIMEOUT (msecs_to_jiffies(10 * 1000))
  35
  36 /*
  37  * Global state maintained for transaction that is being processed. For a class
  38  * of integration services, including the "VSS service", the specified protocol
  39  * is a "request/response" protocol which means that there can only be single
  40  * outstanding transaction from the host at any given point in time. We use
  41  * this to simplify memory management in this driver - we cache and process
  42  * only one message at a time.
  43  *
  44  * While the request/response protocol is guaranteed by the host, we further
  45  * ensure this by serializing packet processing in this driver - we do not
  46  * read additional packets from the VMBUs until the current packet is fully
  47  * handled.
  48  */
  49
  50 static struct {
  51         int state;   /* hvutil_device_state */
  52         int recv_len; /* number of bytes received. */
  53         struct vmbus_channel *recv_channel; /* chn we got the request */
  54         u64 recv_req_id; /* request ID. */
  55         struct hv_vss_msg  *msg; /* current message */
  56 } vss_transaction;
  57
  58
  59 static void vss_respond_to_host(int error);
  60
  61 /*
  62  * This state maintains the version number registered by the daemon.
  63  */
  64 static int dm_reg_value;
  65
  66 static const char vss_devname[] = "vmbus/hv_vss";
  67 static __u8 *recv_buffer;
  68 static struct hvutil_transport *hvt;
  69
  70 static void vss_timeout_func(struct work_struct *dummy);
  71 static void vss_handle_request(struct work_struct *dummy);
  72
  73 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
  74 static DECLARE_WORK(vss_handle_request_work, vss_handle_request);
  75
  76 static void vss_poll_wrapper(void *channel)
  77 {
  78         /* Transaction is finished, reset the state here to avoid races. */
  79         vss_transaction.state = HVUTIL_READY;
  80         hv_vss_onchannelcallback(channel);
  81 }
  82
  83 /*
  84  * Callback when data is received from user mode.
  85  */
  86
  87 static void vss_timeout_func(struct work_struct *dummy)
  88 {
  89         /*
  90          * Timeout waiting for userspace component to reply happened.
  91          */
  92         pr_warn("VSS: timeout waiting for daemon to reply\n");
  93         vss_respond_to_host(HV_E_FAIL);
  94
  95         hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
  96 }
  97
  98 static void vss_register_done(void)
  99 {
 100         hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
 101         pr_debug("VSS: userspace daemon registered\n");
 102 }
 103
 104 static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
 105 {
 106         u32 our_ver = VSS_OP_REGISTER1;
 107
 108         switch (vss_msg->vss_hdr.operation) {
 109         case VSS_OP_REGISTER:
 110                 /* Daemon doesn't expect us to reply */
 111                 dm_reg_value = VSS_OP_REGISTER;
 112                 break;
 113         case VSS_OP_REGISTER1:
 114                 /* Daemon expects us to reply with our own version */
 115                 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
 116                                           vss_register_done))
 117                         return -EFAULT;
 118                 dm_reg_value = VSS_OP_REGISTER1;
 119                 break;
 120         default:
 121                 return -EINVAL;
 122         }
 123         pr_debug("VSS: userspace daemon ver. %d connected\n", dm_reg_value);
 124         return 0;
 125 }
 126
 127 static int vss_on_msg(void *msg, int len)
 128 {
 129         struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;
 130
 131         if (len != sizeof(*vss_msg))
 132                 return -EINVAL;
 133
 134         if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||
 135             vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
 136                 /*
 137                  * Don't process registration messages if we're in the middle
 138                  * of a transaction processing.
 139                  */
 140                 if (vss_transaction.state > HVUTIL_READY)
 141                         return -EINVAL;
 142                 return vss_handle_handshake(vss_msg);
 143         } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
 144                 vss_transaction.state = HVUTIL_USERSPACE_RECV;
 145                 if (cancel_delayed_work_sync(&vss_timeout_work)) {
 146                         vss_respond_to_host(vss_msg->error);
 147                         /* Transaction is finished, reset the state. */
 148                         hv_poll_channel(vss_transaction.recv_channel,
 149                                         vss_poll_wrapper);
 150                 }
 151         } else {
 152                 /* This is a spurious call! */
 153                 pr_warn("VSS: Transaction not active\n");
 154                 return -EINVAL;
 155         }
 156         return 0;
 157 }
 158
 159 static void vss_send_op(void)
 160 {
 161         int op = vss_transaction.msg->vss_hdr.operation;
 162         int rc;
 163         struct hv_vss_msg *vss_msg;
 164
 165         /* The transaction state is wrong. */
 166         if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED)
 167                 return;
 168
 169         vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
 170         if (!vss_msg)
 171                 return;
 172
 173         vss_msg->vss_hdr.operation = op;
 174
 175         vss_transaction.state = HVUTIL_USERSPACE_REQ;
 176
 177         schedule_delayed_work(&vss_timeout_work, VSS_USERSPACE_TIMEOUT);
 178
 179         rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
 180         if (rc) {
 181                 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
 182                 if (cancel_delayed_work_sync(&vss_timeout_work)) {
 183                         vss_respond_to_host(HV_E_FAIL);
 184                         vss_transaction.state = HVUTIL_READY;
 185                 }
 186         }
 187
 188         kfree(vss_msg);
 189
 190         return;
 191 }
 192
 193 static void vss_handle_request(struct work_struct *dummy)
 194 {
 195         switch (vss_transaction.msg->vss_hdr.operation) {
 196         /*
 197          * Initiate a "freeze/thaw" operation in the guest.
 198          * We respond to the host once the operation is complete.
 199          *
 200          * We send the message to the user space daemon and the operation is
 201          * performed in the daemon.
 202          */
 203         case VSS_OP_THAW:
 204         case VSS_OP_FREEZE:
 205                 if (vss_transaction.state < HVUTIL_READY) {
 206                         /* Userspace is not registered yet */
 207                         vss_respond_to_host(HV_E_FAIL);
 208                         return;
 209                 }
 210                 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
 211                 vss_send_op();
 212                 return;
 213         case VSS_OP_HOT_BACKUP:
 214                 vss_transaction.msg->vss_cf.flags = VSS_HBU_NO_AUTO_RECOVERY;
 215                 break;
 216         case VSS_OP_GET_DM_INFO:
 217                 vss_transaction.msg->dm_info.flags = 0;
 218                 break;
 219         default:
 220                 break;
 221         }
 222
 223         vss_respond_to_host(0);
 224         hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
 225 }
 226
 227 /*
 228  * Send a response back to the host.
 229  */
 230
 231 static void
 232 vss_respond_to_host(int error)
 233 {
 234         struct icmsg_hdr *icmsghdrp;
 235         u32     buf_len;
 236         struct vmbus_channel *channel;
 237         u64     req_id;
 238
 239         /*
 240          * Copy the global state for completing the transaction. Note that
 241          * only one transaction can be active at a time.
 242          */
 243
 244         buf_len = vss_transaction.recv_len;
 245         channel = vss_transaction.recv_channel;
 246         req_id = vss_transaction.recv_req_id;
 247
 248         icmsghdrp = (struct icmsg_hdr *)
 249                         &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 250
 251         if (channel->onchannel_callback == NULL)
 252                 /*
 253                  * We have raced with util driver being unloaded;
 254                  * silently return.
 255                  */
 256                 return;
 257
 258         icmsghdrp->status = error;
 259
 260         icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 261
 262         vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 263                                 VM_PKT_DATA_INBAND, 0);
 264
 265 }
 266
 267 /*
 268  * This callback is invoked when we get a VSS message from the host.
 269  * The host ensures that only one VSS transaction can be active at a time.
 270  */
 271
 272 void hv_vss_onchannelcallback(void *context)
 273 {
 274         struct vmbus_channel *channel = context;
 275         u32 recvlen;
 276         u64 requestid;
 277         struct hv_vss_msg *vss_msg;
 278
 279
 280         struct icmsg_hdr *icmsghdrp;
 281         struct icmsg_negotiate *negop = NULL;
 282
 283         if (vss_transaction.state > HVUTIL_READY)
 284                 return;
 285
 286         vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
 287                          &requestid);
 288
 289         if (recvlen > 0) {
 290                 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
 291                         sizeof(struct vmbuspipe_hdr)];
 292
 293                 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 294                         vmbus_prep_negotiate_resp(icmsghdrp, negop,
 295                                  recv_buffer, UTIL_FW_VERSION,
 296                                  VSS_VERSION);
 297                 } else {
 298                         vss_msg = (struct hv_vss_msg *)&recv_buffer[
 299                                 sizeof(struct vmbuspipe_hdr) +
 300                                 sizeof(struct icmsg_hdr)];
 301
 302                         /*
 303                          * Stash away this global state for completing the
 304                          * transaction; note transactions are serialized.
 305                          */
 306
 307                         vss_transaction.recv_len = recvlen;
 308                         vss_transaction.recv_req_id = requestid;
 309                         vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
 310
 311                         schedule_work(&vss_handle_request_work);
 312                         return;
 313                 }
 314
 315                 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
 316                         | ICMSGHDRFLAG_RESPONSE;
 317
 318                 vmbus_sendpacket(channel, recv_buffer,
 319                                        recvlen, requestid,
 320                                        VM_PKT_DATA_INBAND, 0);
 321         }
 322
 323 }
 324
 325 static void vss_on_reset(void)
 326 {
 327         if (cancel_delayed_work_sync(&vss_timeout_work))
 328                 vss_respond_to_host(HV_E_FAIL);
 329         vss_transaction.state = HVUTIL_DEVICE_INIT;
 330 }
 331
 332 int
 333 hv_vss_init(struct hv_util_service *srv)
 334 {
 335         if (vmbus_proto_version < VERSION_WIN8_1) {
 336                 pr_warn("Integration service 'Backup (volume snapshot)'"
 337                         " not supported on this host version.\n");
 338                 return -ENOTSUPP;
 339         }
 340         recv_buffer = srv->recv_buffer;
 341         vss_transaction.recv_channel = srv->channel;
 342
 343         /*
 344          * When this driver loads, the user level daemon that
 345          * processes the host requests may not yet be running.
 346          * Defer processing channel callbacks until the daemon
 347          * has registered.
 348          */
 349         vss_transaction.state = HVUTIL_DEVICE_INIT;
 350
 351         hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
 352                                     vss_on_msg, vss_on_reset);
 353         if (!hvt)
 354                 return -EFAULT;
 355
 356         return 0;
 357 }
 358
 359 void hv_vss_deinit(void)
 360 {
 361         vss_transaction.state = HVUTIL_DEVICE_DYING;
 362         cancel_delayed_work_sync(&vss_timeout_work);
 363         cancel_work_sync(&vss_handle_request_work);
 364         hvutil_transport_destroy(hvt);
 365 }