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 void *vss_context; /* for the channel callback */ 57 } vss_transaction; 58 59 60 static void vss_respond_to_host(int error); 61 62 /* 63 * This state maintains the version number registered by the daemon. 64 */ 65 static int dm_reg_value; 66 67 static const char vss_devname[] = "vmbus/hv_vss"; 68 static __u8 *recv_buffer; 69 static struct hvutil_transport *hvt; 70 71 static void vss_send_op(struct work_struct *dummy); 72 static void vss_timeout_func(struct work_struct *dummy); 73 74 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func); 75 static DECLARE_WORK(vss_send_op_work, vss_send_op); 76 77 /* 78 * Callback when data is received from user mode. 79 */ 80 81 static void vss_timeout_func(struct work_struct *dummy) 82 { 83 /* 84 * Timeout waiting for userspace component to reply happened. 85 */ 86 pr_warn("VSS: timeout waiting for daemon to reply\n"); 87 vss_respond_to_host(HV_E_FAIL); 88 89 /* Transaction is finished, reset the state. */ 90 if (vss_transaction.state > HVUTIL_READY) 91 vss_transaction.state = HVUTIL_READY; 92 93 hv_poll_channel(vss_transaction.vss_context, 94 hv_vss_onchannelcallback); 95 } 96 97 static int vss_handle_handshake(struct hv_vss_msg *vss_msg) 98 { 99 u32 our_ver = VSS_OP_REGISTER1; 100 101 switch (vss_msg->vss_hdr.operation) { 102 case VSS_OP_REGISTER: 103 /* Daemon doesn't expect us to reply */ 104 dm_reg_value = VSS_OP_REGISTER; 105 break; 106 case VSS_OP_REGISTER1: 107 /* Daemon expects us to reply with our own version*/ 108 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver))) 109 return -EFAULT; 110 dm_reg_value = VSS_OP_REGISTER1; 111 break; 112 default: 113 return -EINVAL; 114 } 115 vss_transaction.state = HVUTIL_READY; 116 pr_debug("VSS: userspace daemon ver. %d registered\n", dm_reg_value); 117 return 0; 118 } 119 120 static int vss_on_msg(void *msg, int len) 121 { 122 struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg; 123 124 if (len != sizeof(*vss_msg)) 125 return -EINVAL; 126 127 if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER || 128 vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) { 129 /* 130 * Don't process registration messages if we're in the middle 131 * of a transaction processing. 132 */ 133 if (vss_transaction.state > HVUTIL_READY) 134 return -EINVAL; 135 return vss_handle_handshake(vss_msg); 136 } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) { 137 vss_transaction.state = HVUTIL_USERSPACE_RECV; 138 if (cancel_delayed_work_sync(&vss_timeout_work)) { 139 vss_respond_to_host(vss_msg->error); 140 /* Transaction is finished, reset the state. */ 141 vss_transaction.state = HVUTIL_READY; 142 hv_poll_channel(vss_transaction.vss_context, 143 hv_vss_onchannelcallback); 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 /* 243 * We will defer processing this callback once 244 * the current transaction is complete. 245 */ 246 vss_transaction.vss_context = context; 247 return; 248 } 249 vss_transaction.vss_context = NULL; 250 251 vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen, 252 &requestid); 253 254 if (recvlen > 0) { 255 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[ 256 sizeof(struct vmbuspipe_hdr)]; 257 258 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) { 259 vmbus_prep_negotiate_resp(icmsghdrp, negop, 260 recv_buffer, UTIL_FW_VERSION, 261 VSS_VERSION); 262 } else { 263 vss_msg = (struct hv_vss_msg *)&recv_buffer[ 264 sizeof(struct vmbuspipe_hdr) + 265 sizeof(struct icmsg_hdr)]; 266 267 /* 268 * Stash away this global state for completing the 269 * transaction; note transactions are serialized. 270 */ 271 272 vss_transaction.recv_len = recvlen; 273 vss_transaction.recv_channel = channel; 274 vss_transaction.recv_req_id = requestid; 275 vss_transaction.msg = (struct hv_vss_msg *)vss_msg; 276 277 switch (vss_msg->vss_hdr.operation) { 278 /* 279 * Initiate a "freeze/thaw" 280 * operation in the guest. 281 * We respond to the host once 282 * the operation is complete. 283 * 284 * We send the message to the 285 * user space daemon and the 286 * operation is performed in 287 * the daemon. 288 */ 289 case VSS_OP_FREEZE: 290 case VSS_OP_THAW: 291 if (vss_transaction.state < HVUTIL_READY) { 292 /* Userspace is not registered yet */ 293 vss_respond_to_host(HV_E_FAIL); 294 return; 295 } 296 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED; 297 schedule_work(&vss_send_op_work); 298 schedule_delayed_work(&vss_timeout_work, 299 VSS_USERSPACE_TIMEOUT); 300 return; 301 302 case VSS_OP_HOT_BACKUP: 303 vss_msg->vss_cf.flags = 304 VSS_HBU_NO_AUTO_RECOVERY; 305 vss_respond_to_host(0); 306 return; 307 308 case VSS_OP_GET_DM_INFO: 309 vss_msg->dm_info.flags = 0; 310 vss_respond_to_host(0); 311 return; 312 313 default: 314 vss_respond_to_host(0); 315 return; 316 317 } 318 319 } 320 321 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION 322 | ICMSGHDRFLAG_RESPONSE; 323 324 vmbus_sendpacket(channel, recv_buffer, 325 recvlen, requestid, 326 VM_PKT_DATA_INBAND, 0); 327 } 328 329 } 330 331 static void vss_on_reset(void) 332 { 333 if (cancel_delayed_work_sync(&vss_timeout_work)) 334 vss_respond_to_host(HV_E_FAIL); 335 vss_transaction.state = HVUTIL_DEVICE_INIT; 336 } 337 338 int 339 hv_vss_init(struct hv_util_service *srv) 340 { 341 recv_buffer = srv->recv_buffer; 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_send_op_work); 364 hvutil_transport_destroy(hvt); 365 } 366