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 } 369