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