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_send_op(struct work_struct *dummy); 71 static void vss_timeout_func(struct work_struct *dummy); 72 73 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func); 74 static DECLARE_WORK(vss_send_op_work, vss_send_op); 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 if (cancel_delayed_work_sync(&vss_timeout_work)) { 146 vss_respond_to_host(vss_msg->error); 147 /* Transaction is finished, reset the state. */ 148 hv_poll_channel(vss_transaction.recv_channel, 149 vss_poll_wrapper); 150 } 151 } else { 152 /* This is a spurious call! */ 153 pr_warn("VSS: Transaction not active\n"); 154 return -EINVAL; 155 } 156 return 0; 157 } 158 159 160 static void vss_send_op(struct work_struct *dummy) 161 { 162 int op = vss_transaction.msg->vss_hdr.operation; 163 int rc; 164 struct hv_vss_msg *vss_msg; 165 166 /* The transaction state is wrong. */ 167 if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) 168 return; 169 170 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL); 171 if (!vss_msg) 172 return; 173 174 vss_msg->vss_hdr.operation = op; 175 176 vss_transaction.state = HVUTIL_USERSPACE_REQ; 177 rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL); 178 if (rc) { 179 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc); 180 if (cancel_delayed_work_sync(&vss_timeout_work)) { 181 vss_respond_to_host(HV_E_FAIL); 182 vss_transaction.state = HVUTIL_READY; 183 } 184 } 185 186 kfree(vss_msg); 187 188 return; 189 } 190 191 /* 192 * Send a response back to the host. 193 */ 194 195 static void 196 vss_respond_to_host(int error) 197 { 198 struct icmsg_hdr *icmsghdrp; 199 u32 buf_len; 200 struct vmbus_channel *channel; 201 u64 req_id; 202 203 /* 204 * Copy the global state for completing the transaction. Note that 205 * only one transaction can be active at a time. 206 */ 207 208 buf_len = vss_transaction.recv_len; 209 channel = vss_transaction.recv_channel; 210 req_id = vss_transaction.recv_req_id; 211 212 icmsghdrp = (struct icmsg_hdr *) 213 &recv_buffer[sizeof(struct vmbuspipe_hdr)]; 214 215 if (channel->onchannel_callback == NULL) 216 /* 217 * We have raced with util driver being unloaded; 218 * silently return. 219 */ 220 return; 221 222 icmsghdrp->status = error; 223 224 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE; 225 226 vmbus_sendpacket(channel, recv_buffer, buf_len, req_id, 227 VM_PKT_DATA_INBAND, 0); 228 229 } 230 231 /* 232 * This callback is invoked when we get a VSS message from the host. 233 * The host ensures that only one VSS transaction can be active at a time. 234 */ 235 236 void hv_vss_onchannelcallback(void *context) 237 { 238 struct vmbus_channel *channel = context; 239 u32 recvlen; 240 u64 requestid; 241 struct hv_vss_msg *vss_msg; 242 243 244 struct icmsg_hdr *icmsghdrp; 245 struct icmsg_negotiate *negop = NULL; 246 247 if (vss_transaction.state > HVUTIL_READY) 248 return; 249 250 vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen, 251 &requestid); 252 253 if (recvlen > 0) { 254 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[ 255 sizeof(struct vmbuspipe_hdr)]; 256 257 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) { 258 vmbus_prep_negotiate_resp(icmsghdrp, negop, 259 recv_buffer, UTIL_FW_VERSION, 260 VSS_VERSION); 261 } else { 262 vss_msg = (struct hv_vss_msg *)&recv_buffer[ 263 sizeof(struct vmbuspipe_hdr) + 264 sizeof(struct icmsg_hdr)]; 265 266 /* 267 * Stash away this global state for completing the 268 * transaction; note transactions are serialized. 269 */ 270 271 vss_transaction.recv_len = recvlen; 272 vss_transaction.recv_req_id = requestid; 273 vss_transaction.msg = (struct hv_vss_msg *)vss_msg; 274 275 switch (vss_msg->vss_hdr.operation) { 276 /* 277 * Initiate a "freeze/thaw" 278 * operation in the guest. 279 * We respond to the host once 280 * the operation is complete. 281 * 282 * We send the message to the 283 * user space daemon and the 284 * operation is performed in 285 * the daemon. 286 */ 287 case VSS_OP_FREEZE: 288 case VSS_OP_THAW: 289 if (vss_transaction.state < HVUTIL_READY) { 290 /* Userspace is not registered yet */ 291 vss_respond_to_host(HV_E_FAIL); 292 return; 293 } 294 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED; 295 schedule_work(&vss_send_op_work); 296 schedule_delayed_work(&vss_timeout_work, 297 VSS_USERSPACE_TIMEOUT); 298 return; 299 300 case VSS_OP_HOT_BACKUP: 301 vss_msg->vss_cf.flags = 302 VSS_HBU_NO_AUTO_RECOVERY; 303 vss_respond_to_host(0); 304 return; 305 306 case VSS_OP_GET_DM_INFO: 307 vss_msg->dm_info.flags = 0; 308 vss_respond_to_host(0); 309 return; 310 311 default: 312 vss_respond_to_host(0); 313 return; 314 315 } 316 317 } 318 319 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION 320 | ICMSGHDRFLAG_RESPONSE; 321 322 vmbus_sendpacket(channel, recv_buffer, 323 recvlen, requestid, 324 VM_PKT_DATA_INBAND, 0); 325 } 326 327 } 328 329 static void vss_on_reset(void) 330 { 331 if (cancel_delayed_work_sync(&vss_timeout_work)) 332 vss_respond_to_host(HV_E_FAIL); 333 vss_transaction.state = HVUTIL_DEVICE_INIT; 334 } 335 336 int 337 hv_vss_init(struct hv_util_service *srv) 338 { 339 if (vmbus_proto_version < VERSION_WIN8_1) { 340 pr_warn("Integration service 'Backup (volume snapshot)'" 341 " not supported on this host version.\n"); 342 return -ENOTSUPP; 343 } 344 recv_buffer = srv->recv_buffer; 345 vss_transaction.recv_channel = srv->channel; 346 347 /* 348 * When this driver loads, the user level daemon that 349 * processes the host requests may not yet be running. 350 * Defer processing channel callbacks until the daemon 351 * has registered. 352 */ 353 vss_transaction.state = HVUTIL_DEVICE_INIT; 354 355 hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL, 356 vss_on_msg, vss_on_reset); 357 if (!hvt) 358 return -EFAULT; 359 360 return 0; 361 } 362 363 void hv_vss_deinit(void) 364 { 365 vss_transaction.state = HVUTIL_DEVICE_DYING; 366 cancel_delayed_work_sync(&vss_timeout_work); 367 cancel_work_sync(&vss_send_op_work); 368 hvutil_transport_destroy(hvt); 369 } 370