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 83 static void vss_timeout_func(struct work_struct *dummy); 84 static void vss_handle_request(struct work_struct *dummy); 85 86 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func); 87 static DECLARE_WORK(vss_handle_request_work, vss_handle_request); 88 89 static void vss_poll_wrapper(void *channel) 90 { 91 /* Transaction is finished, reset the state here to avoid races. */ 92 vss_transaction.state = HVUTIL_READY; 93 hv_vss_onchannelcallback(channel); 94 } 95 96 /* 97 * Callback when data is received from user mode. 98 */ 99 100 static void vss_timeout_func(struct work_struct *dummy) 101 { 102 /* 103 * Timeout waiting for userspace component to reply happened. 104 */ 105 pr_warn("VSS: timeout waiting for daemon to reply\n"); 106 vss_respond_to_host(HV_E_FAIL); 107 108 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 109 } 110 111 static void vss_register_done(void) 112 { 113 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 114 pr_debug("VSS: userspace daemon registered\n"); 115 } 116 117 static int vss_handle_handshake(struct hv_vss_msg *vss_msg) 118 { 119 u32 our_ver = VSS_OP_REGISTER1; 120 121 switch (vss_msg->vss_hdr.operation) { 122 case VSS_OP_REGISTER: 123 /* Daemon doesn't expect us to reply */ 124 dm_reg_value = VSS_OP_REGISTER; 125 break; 126 case VSS_OP_REGISTER1: 127 /* Daemon expects us to reply with our own version */ 128 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver), 129 vss_register_done)) 130 return -EFAULT; 131 dm_reg_value = VSS_OP_REGISTER1; 132 break; 133 default: 134 return -EINVAL; 135 } 136 pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value); 137 return 0; 138 } 139 140 static int vss_on_msg(void *msg, int len) 141 { 142 struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg; 143 144 if (len != sizeof(*vss_msg)) { 145 pr_debug("VSS: Message size does not match length\n"); 146 return -EINVAL; 147 } 148 149 if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER || 150 vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) { 151 /* 152 * Don't process registration messages if we're in the middle 153 * of a transaction processing. 154 */ 155 if (vss_transaction.state > HVUTIL_READY) { 156 pr_debug("VSS: Got unexpected registration request\n"); 157 return -EINVAL; 158 } 159 160 return vss_handle_handshake(vss_msg); 161 } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) { 162 vss_transaction.state = HVUTIL_USERSPACE_RECV; 163 164 if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP) 165 vss_transaction.msg->vss_cf.flags = 166 VSS_HBU_NO_AUTO_RECOVERY; 167 168 if (cancel_delayed_work_sync(&vss_timeout_work)) { 169 vss_respond_to_host(vss_msg->error); 170 /* Transaction is finished, reset the state. */ 171 hv_poll_channel(vss_transaction.recv_channel, 172 vss_poll_wrapper); 173 } 174 } else { 175 /* This is a spurious call! */ 176 pr_debug("VSS: Transaction not active\n"); 177 return -EINVAL; 178 } 179 return 0; 180 } 181 182 static void vss_send_op(void) 183 { 184 int op = vss_transaction.msg->vss_hdr.operation; 185 int rc; 186 struct hv_vss_msg *vss_msg; 187 188 /* The transaction state is wrong. */ 189 if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) { 190 pr_debug("VSS: Unexpected attempt to send to daemon\n"); 191 return; 192 } 193 194 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL); 195 if (!vss_msg) 196 return; 197 198 vss_msg->vss_hdr.operation = op; 199 200 vss_transaction.state = HVUTIL_USERSPACE_REQ; 201 202 schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ? 203 VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ); 204 205 rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL); 206 if (rc) { 207 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc); 208 if (cancel_delayed_work_sync(&vss_timeout_work)) { 209 vss_respond_to_host(HV_E_FAIL); 210 vss_transaction.state = HVUTIL_READY; 211 } 212 } 213 214 kfree(vss_msg); 215 216 return; 217 } 218 219 static void vss_handle_request(struct work_struct *dummy) 220 { 221 switch (vss_transaction.msg->vss_hdr.operation) { 222 /* 223 * Initiate a "freeze/thaw" operation in the guest. 224 * We respond to the host once the operation is complete. 225 * 226 * We send the message to the user space daemon and the operation is 227 * performed in the daemon. 228 */ 229 case VSS_OP_THAW: 230 case VSS_OP_FREEZE: 231 case VSS_OP_HOT_BACKUP: 232 if (vss_transaction.state < HVUTIL_READY) { 233 /* Userspace is not registered yet */ 234 pr_debug("VSS: Not ready for request.\n"); 235 vss_respond_to_host(HV_E_FAIL); 236 return; 237 } 238 239 pr_debug("VSS: Received request for op code: %d\n", 240 vss_transaction.msg->vss_hdr.operation); 241 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED; 242 vss_send_op(); 243 return; 244 case VSS_OP_GET_DM_INFO: 245 vss_transaction.msg->dm_info.flags = 0; 246 break; 247 default: 248 break; 249 } 250 251 vss_respond_to_host(0); 252 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 253 } 254 255 /* 256 * Send a response back to the host. 257 */ 258 259 static void 260 vss_respond_to_host(int error) 261 { 262 struct icmsg_hdr *icmsghdrp; 263 u32 buf_len; 264 struct vmbus_channel *channel; 265 u64 req_id; 266 267 /* 268 * Copy the global state for completing the transaction. Note that 269 * only one transaction can be active at a time. 270 */ 271 272 buf_len = vss_transaction.recv_len; 273 channel = vss_transaction.recv_channel; 274 req_id = vss_transaction.recv_req_id; 275 276 icmsghdrp = (struct icmsg_hdr *) 277 &recv_buffer[sizeof(struct vmbuspipe_hdr)]; 278 279 if (channel->onchannel_callback == NULL) 280 /* 281 * We have raced with util driver being unloaded; 282 * silently return. 283 */ 284 return; 285 286 icmsghdrp->status = error; 287 288 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE; 289 290 vmbus_sendpacket(channel, recv_buffer, buf_len, req_id, 291 VM_PKT_DATA_INBAND, 0); 292 293 } 294 295 /* 296 * This callback is invoked when we get a VSS message from the host. 297 * The host ensures that only one VSS transaction can be active at a time. 298 */ 299 300 void hv_vss_onchannelcallback(void *context) 301 { 302 struct vmbus_channel *channel = context; 303 u32 recvlen; 304 u64 requestid; 305 struct hv_vss_msg *vss_msg; 306 int vss_srv_version; 307 308 struct icmsg_hdr *icmsghdrp; 309 310 if (vss_transaction.state > HVUTIL_READY) 311 return; 312 313 vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen, 314 &requestid); 315 316 if (recvlen > 0) { 317 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[ 318 sizeof(struct vmbuspipe_hdr)]; 319 320 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) { 321 if (vmbus_prep_negotiate_resp(icmsghdrp, 322 recv_buffer, fw_versions, FW_VER_COUNT, 323 vss_versions, VSS_VER_COUNT, 324 NULL, &vss_srv_version)) { 325 326 pr_info("VSS IC version %d.%d\n", 327 vss_srv_version >> 16, 328 vss_srv_version & 0xFFFF); 329 } 330 } else { 331 vss_msg = (struct hv_vss_msg *)&recv_buffer[ 332 sizeof(struct vmbuspipe_hdr) + 333 sizeof(struct icmsg_hdr)]; 334 335 /* 336 * Stash away this global state for completing the 337 * transaction; note transactions are serialized. 338 */ 339 340 vss_transaction.recv_len = recvlen; 341 vss_transaction.recv_req_id = requestid; 342 vss_transaction.msg = (struct hv_vss_msg *)vss_msg; 343 344 schedule_work(&vss_handle_request_work); 345 return; 346 } 347 348 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION 349 | ICMSGHDRFLAG_RESPONSE; 350 351 vmbus_sendpacket(channel, recv_buffer, 352 recvlen, requestid, 353 VM_PKT_DATA_INBAND, 0); 354 } 355 356 } 357 358 static void vss_on_reset(void) 359 { 360 if (cancel_delayed_work_sync(&vss_timeout_work)) 361 vss_respond_to_host(HV_E_FAIL); 362 vss_transaction.state = HVUTIL_DEVICE_INIT; 363 } 364 365 int 366 hv_vss_init(struct hv_util_service *srv) 367 { 368 if (vmbus_proto_version < VERSION_WIN8_1) { 369 pr_warn("Integration service 'Backup (volume snapshot)'" 370 " not supported on this host version.\n"); 371 return -ENOTSUPP; 372 } 373 recv_buffer = srv->recv_buffer; 374 vss_transaction.recv_channel = srv->channel; 375 376 /* 377 * When this driver loads, the user level daemon that 378 * processes the host requests may not yet be running. 379 * Defer processing channel callbacks until the daemon 380 * has registered. 381 */ 382 vss_transaction.state = HVUTIL_DEVICE_INIT; 383 384 hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL, 385 vss_on_msg, vss_on_reset); 386 if (!hvt) { 387 pr_warn("VSS: Failed to initialize transport\n"); 388 return -EFAULT; 389 } 390 391 return 0; 392 } 393 394 void hv_vss_deinit(void) 395 { 396 vss_transaction.state = HVUTIL_DEVICE_DYING; 397 cancel_delayed_work_sync(&vss_timeout_work); 398 cancel_work_sync(&vss_handle_request_work); 399 hvutil_transport_destroy(hvt); 400 } 401