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
 146                 if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)
 147                         vss_transaction.msg->vss_cf.flags =
 148                                 VSS_HBU_NO_AUTO_RECOVERY;
 149
 150                 if (cancel_delayed_work_sync(&vss_timeout_work)) {
 151                         vss_respond_to_host(vss_msg->error);
 152                         /* Transaction is finished, reset the state. */
 153                         hv_poll_channel(vss_transaction.recv_channel,
 154                                         vss_poll_wrapper);
 155                 }
 156         } else {
 157                 /* This is a spurious call! */
 158                 pr_warn("VSS: Transaction not active\n");
 159                 return -EINVAL;
 160         }
 161         return 0;
 162 }
 163
 164 static void vss_send_op(void)
 165 {
 166         int op = vss_transaction.msg->vss_hdr.operation;
 167         int rc;
 168         struct hv_vss_msg *vss_msg;
 169
 170         /* The transaction state is wrong. */
 171         if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED)
 172                 return;
 173
 174         vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
 175         if (!vss_msg)
 176                 return;
 177
 178         vss_msg->vss_hdr.operation = op;
 179
 180         vss_transaction.state = HVUTIL_USERSPACE_REQ;
 181
 182         schedule_delayed_work(&vss_timeout_work, VSS_USERSPACE_TIMEOUT);
 183
 184         rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
 185         if (rc) {
 186                 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
 187                 if (cancel_delayed_work_sync(&vss_timeout_work)) {
 188                         vss_respond_to_host(HV_E_FAIL);
 189                         vss_transaction.state = HVUTIL_READY;
 190                 }
 191         }
 192
 193         kfree(vss_msg);
 194
 195         return;
 196 }
 197
 198 static void vss_handle_request(struct work_struct *dummy)
 199 {
 200         switch (vss_transaction.msg->vss_hdr.operation) {
 201         /*
 202          * Initiate a "freeze/thaw" operation in the guest.
 203          * We respond to the host once the operation is complete.
 204          *
 205          * We send the message to the user space daemon and the operation is
 206          * performed in the daemon.
 207          */
 208         case VSS_OP_THAW:
 209         case VSS_OP_FREEZE:
 210         case VSS_OP_HOT_BACKUP:
 211                 if (vss_transaction.state < HVUTIL_READY) {
 212                         /* Userspace is not registered yet */
 213                         vss_respond_to_host(HV_E_FAIL);
 214                         return;
 215                 }
 216                 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
 217                 vss_send_op();
 218                 return;
 219         case VSS_OP_GET_DM_INFO:
 220                 vss_transaction.msg->dm_info.flags = 0;
 221                 break;
 222         default:
 223                 break;
 224         }
 225
 226         vss_respond_to_host(0);
 227         hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
 228 }
 229
 230 /*
 231  * Send a response back to the host.
 232  */
 233
 234 static void
 235 vss_respond_to_host(int error)
 236 {
 237         struct icmsg_hdr *icmsghdrp;
 238         u32     buf_len;
 239         struct vmbus_channel *channel;
 240         u64     req_id;
 241
 242         /*
 243          * Copy the global state for completing the transaction. Note that
 244          * only one transaction can be active at a time.
 245          */
 246
 247         buf_len = vss_transaction.recv_len;
 248         channel = vss_transaction.recv_channel;
 249         req_id = vss_transaction.recv_req_id;
 250
 251         icmsghdrp = (struct icmsg_hdr *)
 252                         &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 253
 254         if (channel->onchannel_callback == NULL)
 255                 /*
 256                  * We have raced with util driver being unloaded;
 257                  * silently return.
 258                  */
 259                 return;
 260
 261         icmsghdrp->status = error;
 262
 263         icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 264
 265         vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 266                                 VM_PKT_DATA_INBAND, 0);
 267
 268 }
 269
 270 /*
 271  * This callback is invoked when we get a VSS message from the host.
 272  * The host ensures that only one VSS transaction can be active at a time.
 273  */
 274
 275 void hv_vss_onchannelcallback(void *context)
 276 {
 277         struct vmbus_channel *channel = context;
 278         u32 recvlen;
 279         u64 requestid;
 280         struct hv_vss_msg *vss_msg;
 281
 282
 283         struct icmsg_hdr *icmsghdrp;
 284         struct icmsg_negotiate *negop = NULL;
 285
 286         if (vss_transaction.state > HVUTIL_READY)
 287                 return;
 288
 289         vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
 290                          &requestid);
 291
 292         if (recvlen > 0) {
 293                 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
 294                         sizeof(struct vmbuspipe_hdr)];
 295
 296                 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 297                         vmbus_prep_negotiate_resp(icmsghdrp, negop,
 298                                  recv_buffer, UTIL_FW_VERSION,
 299                                  VSS_VERSION);
 300                 } else {
 301                         vss_msg = (struct hv_vss_msg *)&recv_buffer[
 302                                 sizeof(struct vmbuspipe_hdr) +
 303                                 sizeof(struct icmsg_hdr)];
 304
 305                         /*
 306                          * Stash away this global state for completing the
 307                          * transaction; note transactions are serialized.
 308                          */
 309
 310                         vss_transaction.recv_len = recvlen;
 311                         vss_transaction.recv_req_id = requestid;
 312                         vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
 313
 314                         schedule_work(&vss_handle_request_work);
 315                         return;
 316                 }
 317
 318                 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
 319                         | ICMSGHDRFLAG_RESPONSE;
 320
 321                 vmbus_sendpacket(channel, recv_buffer,
 322                                        recvlen, requestid,
 323                                        VM_PKT_DATA_INBAND, 0);
 324         }
 325
 326 }
 327
 328 static void vss_on_reset(void)
 329 {
 330         if (cancel_delayed_work_sync(&vss_timeout_work))
 331                 vss_respond_to_host(HV_E_FAIL);
 332         vss_transaction.state = HVUTIL_DEVICE_INIT;
 333 }
 334
 335 int
 336 hv_vss_init(struct hv_util_service *srv)
 337 {
 338         if (vmbus_proto_version < VERSION_WIN8_1) {
 339                 pr_warn("Integration service 'Backup (volume snapshot)'"
 340                         " not supported on this host version.\n");
 341                 return -ENOTSUPP;
 342         }
 343         recv_buffer = srv->recv_buffer;
 344         vss_transaction.recv_channel = srv->channel;
 345
 346         /*
 347          * When this driver loads, the user level daemon that
 348          * processes the host requests may not yet be running.
 349          * Defer processing channel callbacks until the daemon
 350          * has registered.
 351          */
 352         vss_transaction.state = HVUTIL_DEVICE_INIT;
 353
 354         hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
 355                                     vss_on_msg, vss_on_reset);
 356         if (!hvt)
 357                 return -EFAULT;
 358
 359         return 0;
 360 }
 361
 362 void hv_vss_deinit(void)
 363 {
 364         vss_transaction.state = HVUTIL_DEVICE_DYING;
 365         cancel_delayed_work_sync(&vss_timeout_work);
 366         cancel_work_sync(&vss_handle_request_work);
 367         hvutil_transport_destroy(hvt);
 368 }