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