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 } 405