1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * An implementation of host initiated guest snapshot. 4 * 5 * Copyright (C) 2013, Microsoft, Inc. 6 * Author : K. Y. Srinivasan <kys@microsoft.com> 7 */ 8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 9 10 #include <linux/net.h> 11 #include <linux/nls.h> 12 #include <linux/connector.h> 13 #include <linux/workqueue.h> 14 #include <linux/hyperv.h> 15 16 #include "hyperv_vmbus.h" 17 #include "hv_utils_transport.h" 18 19 #define VSS_MAJOR 5 20 #define VSS_MINOR 0 21 #define VSS_VERSION (VSS_MAJOR << 16 | VSS_MINOR) 22 23 #define VSS_VER_COUNT 1 24 static const int vss_versions[] = { 25 VSS_VERSION 26 }; 27 28 #define FW_VER_COUNT 1 29 static const int fw_versions[] = { 30 UTIL_FW_VERSION 31 }; 32 33 /* 34 * Timeout values are based on expecations from host 35 */ 36 #define VSS_FREEZE_TIMEOUT (15 * 60) 37 38 /* 39 * Global state maintained for transaction that is being processed. For a class 40 * of integration services, including the "VSS service", the specified protocol 41 * is a "request/response" protocol which means that there can only be single 42 * outstanding transaction from the host at any given point in time. We use 43 * this to simplify memory management in this driver - we cache and process 44 * only one message at a time. 45 * 46 * While the request/response protocol is guaranteed by the host, we further 47 * ensure this by serializing packet processing in this driver - we do not 48 * read additional packets from the VMBUs until the current packet is fully 49 * handled. 50 */ 51 52 static struct { 53 int state; /* hvutil_device_state */ 54 int recv_len; /* number of bytes received. */ 55 struct vmbus_channel *recv_channel; /* chn we got the request */ 56 u64 recv_req_id; /* request ID. */ 57 struct hv_vss_msg *msg; /* current message */ 58 } vss_transaction; 59 60 61 static void vss_respond_to_host(int error); 62 63 /* 64 * This state maintains the version number registered by the daemon. 65 */ 66 static int dm_reg_value; 67 68 static const char vss_devname[] = "vmbus/hv_vss"; 69 static __u8 *recv_buffer; 70 static struct hvutil_transport *hvt; 71 72 static void vss_timeout_func(struct work_struct *dummy); 73 static void vss_handle_request(struct work_struct *dummy); 74 75 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func); 76 static DECLARE_WORK(vss_handle_request_work, vss_handle_request); 77 78 static void vss_poll_wrapper(void *channel) 79 { 80 /* Transaction is finished, reset the state here to avoid races. */ 81 vss_transaction.state = HVUTIL_READY; 82 hv_vss_onchannelcallback(channel); 83 } 84 85 /* 86 * Callback when data is received from user mode. 87 */ 88 89 static void vss_timeout_func(struct work_struct *dummy) 90 { 91 /* 92 * Timeout waiting for userspace component to reply happened. 93 */ 94 pr_warn("VSS: timeout waiting for daemon to reply\n"); 95 vss_respond_to_host(HV_E_FAIL); 96 97 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 98 } 99 100 static void vss_register_done(void) 101 { 102 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 103 pr_debug("VSS: userspace daemon registered\n"); 104 } 105 106 static int vss_handle_handshake(struct hv_vss_msg *vss_msg) 107 { 108 u32 our_ver = VSS_OP_REGISTER1; 109 110 switch (vss_msg->vss_hdr.operation) { 111 case VSS_OP_REGISTER: 112 /* Daemon doesn't expect us to reply */ 113 dm_reg_value = VSS_OP_REGISTER; 114 break; 115 case VSS_OP_REGISTER1: 116 /* Daemon expects us to reply with our own version */ 117 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver), 118 vss_register_done)) 119 return -EFAULT; 120 dm_reg_value = VSS_OP_REGISTER1; 121 break; 122 default: 123 return -EINVAL; 124 } 125 pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value); 126 return 0; 127 } 128 129 static int vss_on_msg(void *msg, int len) 130 { 131 struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg; 132 133 if (len != sizeof(*vss_msg)) { 134 pr_debug("VSS: Message size does not match length\n"); 135 return -EINVAL; 136 } 137 138 if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER || 139 vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) { 140 /* 141 * Don't process registration messages if we're in the middle 142 * of a transaction processing. 143 */ 144 if (vss_transaction.state > HVUTIL_READY) { 145 pr_debug("VSS: Got unexpected registration request\n"); 146 return -EINVAL; 147 } 148 149 return vss_handle_handshake(vss_msg); 150 } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) { 151 vss_transaction.state = HVUTIL_USERSPACE_RECV; 152 153 if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP) 154 vss_transaction.msg->vss_cf.flags = 155 VSS_HBU_NO_AUTO_RECOVERY; 156 157 if (cancel_delayed_work_sync(&vss_timeout_work)) { 158 vss_respond_to_host(vss_msg->error); 159 /* Transaction is finished, reset the state. */ 160 hv_poll_channel(vss_transaction.recv_channel, 161 vss_poll_wrapper); 162 } 163 } else { 164 /* This is a spurious call! */ 165 pr_debug("VSS: Transaction not active\n"); 166 return -EINVAL; 167 } 168 return 0; 169 } 170 171 static void vss_send_op(void) 172 { 173 int op = vss_transaction.msg->vss_hdr.operation; 174 int rc; 175 struct hv_vss_msg *vss_msg; 176 177 /* The transaction state is wrong. */ 178 if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) { 179 pr_debug("VSS: Unexpected attempt to send to daemon\n"); 180 return; 181 } 182 183 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL); 184 if (!vss_msg) 185 return; 186 187 vss_msg->vss_hdr.operation = op; 188 189 vss_transaction.state = HVUTIL_USERSPACE_REQ; 190 191 schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ? 192 VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ); 193 194 rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL); 195 if (rc) { 196 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc); 197 if (cancel_delayed_work_sync(&vss_timeout_work)) { 198 vss_respond_to_host(HV_E_FAIL); 199 vss_transaction.state = HVUTIL_READY; 200 } 201 } 202 203 kfree(vss_msg); 204 } 205 206 static void vss_handle_request(struct work_struct *dummy) 207 { 208 switch (vss_transaction.msg->vss_hdr.operation) { 209 /* 210 * Initiate a "freeze/thaw" operation in the guest. 211 * We respond to the host once the operation is complete. 212 * 213 * We send the message to the user space daemon and the operation is 214 * performed in the daemon. 215 */ 216 case VSS_OP_THAW: 217 case VSS_OP_FREEZE: 218 case VSS_OP_HOT_BACKUP: 219 if (vss_transaction.state < HVUTIL_READY) { 220 /* Userspace is not registered yet */ 221 pr_debug("VSS: Not ready for request.\n"); 222 vss_respond_to_host(HV_E_FAIL); 223 return; 224 } 225 226 pr_debug("VSS: Received request for op code: %d\n", 227 vss_transaction.msg->vss_hdr.operation); 228 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED; 229 vss_send_op(); 230 return; 231 case VSS_OP_GET_DM_INFO: 232 vss_transaction.msg->dm_info.flags = 0; 233 break; 234 default: 235 break; 236 } 237 238 vss_respond_to_host(0); 239 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper); 240 } 241 242 /* 243 * Send a response back to the host. 244 */ 245 246 static void 247 vss_respond_to_host(int error) 248 { 249 struct icmsg_hdr *icmsghdrp; 250 u32 buf_len; 251 struct vmbus_channel *channel; 252 u64 req_id; 253 254 /* 255 * Copy the global state for completing the transaction. Note that 256 * only one transaction can be active at a time. 257 */ 258 259 buf_len = vss_transaction.recv_len; 260 channel = vss_transaction.recv_channel; 261 req_id = vss_transaction.recv_req_id; 262 263 icmsghdrp = (struct icmsg_hdr *) 264 &recv_buffer[sizeof(struct vmbuspipe_hdr)]; 265 266 if (channel->onchannel_callback == NULL) 267 /* 268 * We have raced with util driver being unloaded; 269 * silently return. 270 */ 271 return; 272 273 icmsghdrp->status = error; 274 275 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE; 276 277 vmbus_sendpacket(channel, recv_buffer, buf_len, req_id, 278 VM_PKT_DATA_INBAND, 0); 279 280 } 281 282 /* 283 * This callback is invoked when we get a VSS message from the host. 284 * The host ensures that only one VSS transaction can be active at a time. 285 */ 286 287 void hv_vss_onchannelcallback(void *context) 288 { 289 struct vmbus_channel *channel = context; 290 u32 recvlen; 291 u64 requestid; 292 struct hv_vss_msg *vss_msg; 293 int vss_srv_version; 294 295 struct icmsg_hdr *icmsghdrp; 296 297 if (vss_transaction.state > HVUTIL_READY) 298 return; 299 300 vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen, 301 &requestid); 302 303 if (recvlen > 0) { 304 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[ 305 sizeof(struct vmbuspipe_hdr)]; 306 307 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) { 308 if (vmbus_prep_negotiate_resp(icmsghdrp, 309 recv_buffer, fw_versions, FW_VER_COUNT, 310 vss_versions, VSS_VER_COUNT, 311 NULL, &vss_srv_version)) { 312 313 pr_info("VSS IC version %d.%d\n", 314 vss_srv_version >> 16, 315 vss_srv_version & 0xFFFF); 316 } 317 } else { 318 vss_msg = (struct hv_vss_msg *)&recv_buffer[ 319 sizeof(struct vmbuspipe_hdr) + 320 sizeof(struct icmsg_hdr)]; 321 322 /* 323 * Stash away this global state for completing the 324 * transaction; note transactions are serialized. 325 */ 326 327 vss_transaction.recv_len = recvlen; 328 vss_transaction.recv_req_id = requestid; 329 vss_transaction.msg = (struct hv_vss_msg *)vss_msg; 330 331 schedule_work(&vss_handle_request_work); 332 return; 333 } 334 335 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION 336 | ICMSGHDRFLAG_RESPONSE; 337 338 vmbus_sendpacket(channel, recv_buffer, 339 recvlen, requestid, 340 VM_PKT_DATA_INBAND, 0); 341 } 342 343 } 344 345 static void vss_on_reset(void) 346 { 347 if (cancel_delayed_work_sync(&vss_timeout_work)) 348 vss_respond_to_host(HV_E_FAIL); 349 vss_transaction.state = HVUTIL_DEVICE_INIT; 350 } 351 352 int 353 hv_vss_init(struct hv_util_service *srv) 354 { 355 if (vmbus_proto_version < VERSION_WIN8_1) { 356 pr_warn("Integration service 'Backup (volume snapshot)'" 357 " not supported on this host version.\n"); 358 return -ENOTSUPP; 359 } 360 recv_buffer = srv->recv_buffer; 361 vss_transaction.recv_channel = srv->channel; 362 363 /* 364 * When this driver loads, the user level daemon that 365 * processes the host requests may not yet be running. 366 * Defer processing channel callbacks until the daemon 367 * has registered. 368 */ 369 vss_transaction.state = HVUTIL_DEVICE_INIT; 370 371 hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL, 372 vss_on_msg, vss_on_reset); 373 if (!hvt) { 374 pr_warn("VSS: Failed to initialize transport\n"); 375 return -EFAULT; 376 } 377 378 return 0; 379 } 380 381 void hv_vss_deinit(void) 382 { 383 vss_transaction.state = HVUTIL_DEVICE_DYING; 384 cancel_delayed_work_sync(&vss_timeout_work); 385 cancel_work_sync(&vss_handle_request_work); 386 hvutil_transport_destroy(hvt); 387 } 388