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