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 /* 35 * Timeout values are based on expecations from host 36 */ 37 #define VSS_FREEZE_TIMEOUT (15 * 60) 38 39 /* 40 * Global state maintained for transaction that is being processed. For a class 41 * of integration services, including the "VSS service", the specified protocol 42 * is a "request/response" protocol which means that there can only be single 43 * outstanding transaction from the host at any given point in time. We use 44 * this to simplify memory management in this driver - we cache and process 45 * only one message at a time. 46 * 47 * While the request/response protocol is guaranteed by the host, we further 48 * ensure this by serializing packet processing in this driver - we do not 49 * read additional packets from the VMBUs until the current packet is fully 50 * handled. 51 */ 52 53 static struct { 54 int state; /* hvutil_device_state */ 55 int recv_len; /* number of bytes received. */ 56 struct vmbus_channel *recv_channel; /* chn we got the request */ 57 u64 recv_req_id; /* request ID. */ 58 struct hv_vss_msg *msg; /* current message */ 59 } vss_transaction; 60 61 62 static void vss_respond_to_host(int error); 63 64 /* 65 * This state maintains the version number registered by the daemon. 66 */ 67 static int dm_reg_value; 68 69 static const char vss_devname[] = "vmbus/hv_vss"; 70 static __u8 *recv_buffer; 71 static struct hvutil_transport *hvt; 72 static struct completion release_event; 73 74 static void vss_timeout_func(struct work_struct *dummy); 75 static void vss_handle_request(struct work_struct *dummy); 76 77 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func); 78 static DECLARE_WORK(vss_handle_request_work, vss_handle_request); 79 80 static void vss_poll_wrapper(void *channel) 81 { 82 /* Transaction is finished, reset the state here to avoid races. */ 83 vss_transaction.state = HVUTIL_READY; 84 hv_vss_onchannelcallback(channel); 85 } 86 87 /* 88 * Callback when data is received from user mode. 89 */ 90 91 static void vss_timeout_func(struct work_struct *dummy) 92 { 93 /* 94 * Timeout waiting for userspace component to reply happened. 95 */ 96 pr_warn("VSS: timeout waiting for daemon to reply\n"); 97 vss_respond_to_host(HV_E_FAIL); 98 99 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 100 } 101 102 static void vss_register_done(void) 103 { 104 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 105 pr_debug("VSS: userspace daemon registered\n"); 106 } 107 108 static int vss_handle_handshake(struct hv_vss_msg *vss_msg) 109 { 110 u32 our_ver = VSS_OP_REGISTER1; 111 112 switch (vss_msg->vss_hdr.operation) { 113 case VSS_OP_REGISTER: 114 /* Daemon doesn't expect us to reply */ 115 dm_reg_value = VSS_OP_REGISTER; 116 break; 117 case VSS_OP_REGISTER1: 118 /* Daemon expects us to reply with our own version */ 119 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver), 120 vss_register_done)) 121 return -EFAULT; 122 dm_reg_value = VSS_OP_REGISTER1; 123 break; 124 default: 125 return -EINVAL; 126 } 127 pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value); 128 return 0; 129 } 130 131 static int vss_on_msg(void *msg, int len) 132 { 133 struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg; 134 135 if (len != sizeof(*vss_msg)) { 136 pr_debug("VSS: Message size does not match length\n"); 137 return -EINVAL; 138 } 139 140 if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER || 141 vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) { 142 /* 143 * Don't process registration messages if we're in the middle 144 * of a transaction processing. 145 */ 146 if (vss_transaction.state > HVUTIL_READY) { 147 pr_debug("VSS: Got unexpected registration request\n"); 148 return -EINVAL; 149 } 150 151 return vss_handle_handshake(vss_msg); 152 } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) { 153 vss_transaction.state = HVUTIL_USERSPACE_RECV; 154 155 if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP) 156 vss_transaction.msg->vss_cf.flags = 157 VSS_HBU_NO_AUTO_RECOVERY; 158 159 if (cancel_delayed_work_sync(&vss_timeout_work)) { 160 vss_respond_to_host(vss_msg->error); 161 /* Transaction is finished, reset the state. */ 162 hv_poll_channel(vss_transaction.recv_channel, 163 vss_poll_wrapper); 164 } 165 } else { 166 /* This is a spurious call! */ 167 pr_debug("VSS: Transaction not active\n"); 168 return -EINVAL; 169 } 170 return 0; 171 } 172 173 static void vss_send_op(void) 174 { 175 int op = vss_transaction.msg->vss_hdr.operation; 176 int rc; 177 struct hv_vss_msg *vss_msg; 178 179 /* The transaction state is wrong. */ 180 if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) { 181 pr_debug("VSS: Unexpected attempt to send to daemon\n"); 182 return; 183 } 184 185 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL); 186 if (!vss_msg) 187 return; 188 189 vss_msg->vss_hdr.operation = op; 190 191 vss_transaction.state = HVUTIL_USERSPACE_REQ; 192 193 schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ? 194 VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ); 195 196 rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL); 197 if (rc) { 198 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc); 199 if (cancel_delayed_work_sync(&vss_timeout_work)) { 200 vss_respond_to_host(HV_E_FAIL); 201 vss_transaction.state = HVUTIL_READY; 202 } 203 } 204 205 kfree(vss_msg); 206 207 return; 208 } 209 210 static void vss_handle_request(struct work_struct *dummy) 211 { 212 switch (vss_transaction.msg->vss_hdr.operation) { 213 /* 214 * Initiate a "freeze/thaw" operation in the guest. 215 * We respond to the host once the operation is complete. 216 * 217 * We send the message to the user space daemon and the operation is 218 * performed in the daemon. 219 */ 220 case VSS_OP_THAW: 221 case VSS_OP_FREEZE: 222 case VSS_OP_HOT_BACKUP: 223 if (vss_transaction.state < HVUTIL_READY) { 224 /* Userspace is not registered yet */ 225 pr_debug("VSS: Not ready for request.\n"); 226 vss_respond_to_host(HV_E_FAIL); 227 return; 228 } 229 230 pr_debug("VSS: Received request for op code: %d\n", 231 vss_transaction.msg->vss_hdr.operation); 232 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED; 233 vss_send_op(); 234 return; 235 case VSS_OP_GET_DM_INFO: 236 vss_transaction.msg->dm_info.flags = 0; 237 break; 238 default: 239 break; 240 } 241 242 vss_respond_to_host(0); 243 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 244 } 245 246 /* 247 * Send a response back to the host. 248 */ 249 250 static void 251 vss_respond_to_host(int error) 252 { 253 struct icmsg_hdr *icmsghdrp; 254 u32 buf_len; 255 struct vmbus_channel *channel; 256 u64 req_id; 257 258 /* 259 * Copy the global state for completing the transaction. Note that 260 * only one transaction can be active at a time. 261 */ 262 263 buf_len = vss_transaction.recv_len; 264 channel = vss_transaction.recv_channel; 265 req_id = vss_transaction.recv_req_id; 266 267 icmsghdrp = (struct icmsg_hdr *) 268 &recv_buffer[sizeof(struct vmbuspipe_hdr)]; 269 270 if (channel->onchannel_callback == NULL) 271 /* 272 * We have raced with util driver being unloaded; 273 * silently return. 274 */ 275 return; 276 277 icmsghdrp->status = error; 278 279 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE; 280 281 vmbus_sendpacket(channel, recv_buffer, buf_len, req_id, 282 VM_PKT_DATA_INBAND, 0); 283 284 } 285 286 /* 287 * This callback is invoked when we get a VSS message from the host. 288 * The host ensures that only one VSS transaction can be active at a time. 289 */ 290 291 void hv_vss_onchannelcallback(void *context) 292 { 293 struct vmbus_channel *channel = context; 294 u32 recvlen; 295 u64 requestid; 296 struct hv_vss_msg *vss_msg; 297 298 299 struct icmsg_hdr *icmsghdrp; 300 struct icmsg_negotiate *negop = NULL; 301 302 if (vss_transaction.state > HVUTIL_READY) 303 return; 304 305 vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen, 306 &requestid); 307 308 if (recvlen > 0) { 309 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[ 310 sizeof(struct vmbuspipe_hdr)]; 311 312 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) { 313 vmbus_prep_negotiate_resp(icmsghdrp, negop, 314 recv_buffer, UTIL_FW_VERSION, 315 VSS_VERSION); 316 } else { 317 vss_msg = (struct hv_vss_msg *)&recv_buffer[ 318 sizeof(struct vmbuspipe_hdr) + 319 sizeof(struct icmsg_hdr)]; 320 321 /* 322 * Stash away this global state for completing the 323 * transaction; note transactions are serialized. 324 */ 325 326 vss_transaction.recv_len = recvlen; 327 vss_transaction.recv_req_id = requestid; 328 vss_transaction.msg = (struct hv_vss_msg *)vss_msg; 329 330 schedule_work(&vss_handle_request_work); 331 return; 332 } 333 334 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION 335 | ICMSGHDRFLAG_RESPONSE; 336 337 vmbus_sendpacket(channel, recv_buffer, 338 recvlen, requestid, 339 VM_PKT_DATA_INBAND, 0); 340 } 341 342 } 343 344 static void vss_on_reset(void) 345 { 346 if (cancel_delayed_work_sync(&vss_timeout_work)) 347 vss_respond_to_host(HV_E_FAIL); 348 vss_transaction.state = HVUTIL_DEVICE_INIT; 349 complete(&release_event); 350 } 351 352 int 353 hv_vss_init(struct hv_util_service *srv) 354 { 355 init_completion(&release_event); 356 if (vmbus_proto_version < VERSION_WIN8_1) { 357 pr_warn("Integration service 'Backup (volume snapshot)'" 358 " not supported on this host version.\n"); 359 return -ENOTSUPP; 360 } 361 recv_buffer = srv->recv_buffer; 362 vss_transaction.recv_channel = srv->channel; 363 364 /* 365 * When this driver loads, the user level daemon that 366 * processes the host requests may not yet be running. 367 * Defer processing channel callbacks until the daemon 368 * has registered. 369 */ 370 vss_transaction.state = HVUTIL_DEVICE_INIT; 371 372 hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL, 373 vss_on_msg, vss_on_reset); 374 if (!hvt) { 375 pr_warn("VSS: Failed to initialize transport\n"); 376 return -EFAULT; 377 } 378 379 return 0; 380 } 381 382 void hv_vss_deinit(void) 383 { 384 vss_transaction.state = HVUTIL_DEVICE_DYING; 385 cancel_delayed_work_sync(&vss_timeout_work); 386 cancel_work_sync(&vss_handle_request_work); 387 hvutil_transport_destroy(hvt); 388 wait_for_completion(&release_event); 389 } 390