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 #include <asm/hyperv-tlfs.h>
16
17 #include "hyperv_vmbus.h"
18 #include "hv_utils_transport.h"
19
20 #define VSS_MAJOR 5
21 #define VSS_MINOR 0
22 #define VSS_VERSION (VSS_MAJOR << 16 | VSS_MINOR)
23
24 #define VSS_VER_COUNT 1
25 static const int vss_versions[] = {
26 VSS_VERSION
27 };
28
29 #define FW_VER_COUNT 1
30 static const int fw_versions[] = {
31 UTIL_FW_VERSION
32 };
33
34 /* See comment with struct hv_vss_msg regarding the max VMbus packet size */
35 #define VSS_MAX_PKT_SIZE (HV_HYP_PAGE_SIZE * 2)
36
37 /*
38 * Timeout values are based on expecations from host
39 */
40 #define VSS_FREEZE_TIMEOUT (15 * 60)
41
42 /*
43 * Global state maintained for transaction that is being processed. For a class
44 * of integration services, including the "VSS service", the specified protocol
45 * is a "request/response" protocol which means that there can only be single
46 * outstanding transaction from the host at any given point in time. We use
47 * this to simplify memory management in this driver - we cache and process
48 * only one message at a time.
49 *
50 * While the request/response protocol is guaranteed by the host, we further
51 * ensure this by serializing packet processing in this driver - we do not
52 * read additional packets from the VMBUs until the current packet is fully
53 * handled.
54 */
55
56 static struct {
57 int state; /* hvutil_device_state */
58 int recv_len; /* number of bytes received. */
59 struct vmbus_channel *recv_channel; /* chn we got the request */
60 u64 recv_req_id; /* request ID. */
61 struct hv_vss_msg *msg; /* current message */
62 } vss_transaction;
63
64
65 static void vss_respond_to_host(int error);
66
67 /*
68 * This state maintains the version number registered by the daemon.
69 */
70 static int dm_reg_value;
71
72 static const char vss_devname[] = "vmbus/hv_vss";
73 static __u8 *recv_buffer;
74 static struct hvutil_transport *hvt;
75
76 static void vss_timeout_func(struct work_struct *dummy);
77 static void vss_handle_request(struct work_struct *dummy);
78
79 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
80 static DECLARE_WORK(vss_handle_request_work, vss_handle_request);
81
vss_poll_wrapper(void * channel)82 static void vss_poll_wrapper(void *channel)
83 {
84 /* Transaction is finished, reset the state here to avoid races. */
85 vss_transaction.state = HVUTIL_READY;
86 tasklet_schedule(&((struct vmbus_channel *)channel)->callback_event);
87 }
88
89 /*
90 * Callback when data is received from user mode.
91 */
92
vss_timeout_func(struct work_struct * dummy)93 static void vss_timeout_func(struct work_struct *dummy)
94 {
95 /*
96 * Timeout waiting for userspace component to reply happened.
97 */
98 pr_warn("VSS: timeout waiting for daemon to reply\n");
99 vss_respond_to_host(HV_E_FAIL);
100
101 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
102 }
103
vss_register_done(void)104 static void vss_register_done(void)
105 {
106 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
107 pr_debug("VSS: userspace daemon registered\n");
108 }
109
vss_handle_handshake(struct hv_vss_msg * vss_msg)110 static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
111 {
112 u32 our_ver = VSS_OP_REGISTER1;
113
114 switch (vss_msg->vss_hdr.operation) {
115 case VSS_OP_REGISTER:
116 /* Daemon doesn't expect us to reply */
117 dm_reg_value = VSS_OP_REGISTER;
118 break;
119 case VSS_OP_REGISTER1:
120 /* Daemon expects us to reply with our own version */
121 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
122 vss_register_done))
123 return -EFAULT;
124 dm_reg_value = VSS_OP_REGISTER1;
125 break;
126 default:
127 return -EINVAL;
128 }
129 pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value);
130 return 0;
131 }
132
vss_on_msg(void * msg,int len)133 static int vss_on_msg(void *msg, int len)
134 {
135 struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;
136
137 if (len != sizeof(*vss_msg)) {
138 pr_debug("VSS: Message size does not match length\n");
139 return -EINVAL;
140 }
141
142 if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||
143 vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
144 /*
145 * Don't process registration messages if we're in the middle
146 * of a transaction processing.
147 */
148 if (vss_transaction.state > HVUTIL_READY) {
149 pr_debug("VSS: Got unexpected registration request\n");
150 return -EINVAL;
151 }
152
153 return vss_handle_handshake(vss_msg);
154 } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
155 vss_transaction.state = HVUTIL_USERSPACE_RECV;
156
157 if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)
158 vss_transaction.msg->vss_cf.flags =
159 VSS_HBU_NO_AUTO_RECOVERY;
160
161 if (cancel_delayed_work_sync(&vss_timeout_work)) {
162 vss_respond_to_host(vss_msg->error);
163 /* Transaction is finished, reset the state. */
164 hv_poll_channel(vss_transaction.recv_channel,
165 vss_poll_wrapper);
166 }
167 } else {
168 /* This is a spurious call! */
169 pr_debug("VSS: Transaction not active\n");
170 return -EINVAL;
171 }
172 return 0;
173 }
174
vss_send_op(void)175 static void vss_send_op(void)
176 {
177 int op = vss_transaction.msg->vss_hdr.operation;
178 int rc;
179 struct hv_vss_msg *vss_msg;
180
181 /* The transaction state is wrong. */
182 if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) {
183 pr_debug("VSS: Unexpected attempt to send to daemon\n");
184 return;
185 }
186
187 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
188 if (!vss_msg)
189 return;
190
191 vss_msg->vss_hdr.operation = op;
192
193 vss_transaction.state = HVUTIL_USERSPACE_REQ;
194
195 schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ?
196 secs_to_jiffies(VSS_FREEZE_TIMEOUT) :
197 secs_to_jiffies(HV_UTIL_TIMEOUT));
198
199 rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
200 if (rc) {
201 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
202 if (cancel_delayed_work_sync(&vss_timeout_work)) {
203 vss_respond_to_host(HV_E_FAIL);
204 vss_transaction.state = HVUTIL_READY;
205 }
206 }
207
208 kfree(vss_msg);
209 }
210
vss_handle_request(struct work_struct * dummy)211 static void vss_handle_request(struct work_struct *dummy)
212 {
213 switch (vss_transaction.msg->vss_hdr.operation) {
214 /*
215 * Initiate a "freeze/thaw" operation in the guest.
216 * We respond to the host once the operation is complete.
217 *
218 * We send the message to the user space daemon and the operation is
219 * performed in the daemon.
220 */
221 case VSS_OP_THAW:
222 case VSS_OP_FREEZE:
223 case VSS_OP_HOT_BACKUP:
224 if (vss_transaction.state < HVUTIL_READY) {
225 /* Userspace is not registered yet */
226 pr_debug("VSS: Not ready for request.\n");
227 vss_respond_to_host(HV_E_FAIL);
228 return;
229 }
230
231 pr_debug("VSS: Received request for op code: %d\n",
232 vss_transaction.msg->vss_hdr.operation);
233 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
234 vss_send_op();
235 return;
236 case VSS_OP_GET_DM_INFO:
237 vss_transaction.msg->dm_info.flags = 0;
238 break;
239 default:
240 break;
241 }
242
243 vss_respond_to_host(0);
244 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
245 }
246
247 /*
248 * Send a response back to the host.
249 */
250
251 static void
vss_respond_to_host(int error)252 vss_respond_to_host(int error)
253 {
254 struct icmsg_hdr *icmsghdrp;
255 u32 buf_len;
256 struct vmbus_channel *channel;
257 u64 req_id;
258
259 /*
260 * Copy the global state for completing the transaction. Note that
261 * only one transaction can be active at a time.
262 */
263
264 buf_len = vss_transaction.recv_len;
265 channel = vss_transaction.recv_channel;
266 req_id = vss_transaction.recv_req_id;
267
268 icmsghdrp = (struct icmsg_hdr *)
269 &recv_buffer[sizeof(struct vmbuspipe_hdr)];
270
271 if (channel->onchannel_callback == NULL)
272 /*
273 * We have raced with util driver being unloaded;
274 * silently return.
275 */
276 return;
277
278 icmsghdrp->status = error;
279
280 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
281
282 vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
283 VM_PKT_DATA_INBAND, 0);
284
285 }
286
287 /*
288 * This callback is invoked when we get a VSS message from the host.
289 * The host ensures that only one VSS transaction can be active at a time.
290 */
291
hv_vss_onchannelcallback(void * context)292 void hv_vss_onchannelcallback(void *context)
293 {
294 struct vmbus_channel *channel = context;
295 u32 recvlen;
296 u64 requestid;
297 struct hv_vss_msg *vss_msg;
298 int vss_srv_version;
299
300 struct icmsg_hdr *icmsghdrp;
301
302 if (vss_transaction.state > HVUTIL_READY)
303 return;
304
305 if (vmbus_recvpacket(channel, recv_buffer, VSS_MAX_PKT_SIZE, &recvlen, &requestid)) {
306 pr_err_ratelimited("VSS request received. Could not read into recv buf\n");
307 return;
308 }
309
310 if (!recvlen)
311 return;
312
313 /* Ensure recvlen is big enough to read header data */
314 if (recvlen < ICMSG_HDR) {
315 pr_err_ratelimited("VSS request received. Packet length too small: %d\n",
316 recvlen);
317 return;
318 }
319
320 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[sizeof(struct vmbuspipe_hdr)];
321
322 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
323 if (vmbus_prep_negotiate_resp(icmsghdrp,
324 recv_buffer, recvlen,
325 fw_versions, FW_VER_COUNT,
326 vss_versions, VSS_VER_COUNT,
327 NULL, &vss_srv_version)) {
328
329 pr_info("VSS IC version %d.%d\n",
330 vss_srv_version >> 16,
331 vss_srv_version & 0xFFFF);
332 }
333 } else if (icmsghdrp->icmsgtype == ICMSGTYPE_VSS) {
334 /* Ensure recvlen is big enough to contain hv_vss_msg */
335 if (recvlen < ICMSG_HDR + sizeof(struct hv_vss_msg)) {
336 pr_err_ratelimited("Invalid VSS msg. Packet length too small: %u\n",
337 recvlen);
338 return;
339 }
340 vss_msg = (struct hv_vss_msg *)&recv_buffer[ICMSG_HDR];
341
342 /*
343 * Stash away this global state for completing the
344 * transaction; note transactions are serialized.
345 */
346
347 vss_transaction.recv_len = recvlen;
348 vss_transaction.recv_req_id = requestid;
349 vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
350
351 schedule_work(&vss_handle_request_work);
352 return;
353 } else {
354 pr_err_ratelimited("VSS request received. Invalid msg type: %d\n",
355 icmsghdrp->icmsgtype);
356 return;
357 }
358
359 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION |
360 ICMSGHDRFLAG_RESPONSE;
361 vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
362 VM_PKT_DATA_INBAND, 0);
363 }
364
vss_on_reset(void)365 static void vss_on_reset(void)
366 {
367 if (cancel_delayed_work_sync(&vss_timeout_work))
368 vss_respond_to_host(HV_E_FAIL);
369 vss_transaction.state = HVUTIL_DEVICE_INIT;
370 }
371
372 int
hv_vss_init(struct hv_util_service * srv)373 hv_vss_init(struct hv_util_service *srv)
374 {
375 if (vmbus_proto_version < VERSION_WIN8_1) {
376 pr_warn("Integration service 'Backup (volume snapshot)'"
377 " not supported on this host version.\n");
378 return -ENOTSUPP;
379 }
380 recv_buffer = srv->recv_buffer;
381 vss_transaction.recv_channel = srv->channel;
382 vss_transaction.recv_channel->max_pkt_size = VSS_MAX_PKT_SIZE;
383
384 /*
385 * When this driver loads, the user level daemon that
386 * processes the host requests may not yet be running.
387 * Defer processing channel callbacks until the daemon
388 * has registered.
389 */
390 vss_transaction.state = HVUTIL_DEVICE_INIT;
391
392 return 0;
393 }
394
395 int
hv_vss_init_transport(void)396 hv_vss_init_transport(void)
397 {
398 hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
399 vss_on_msg, vss_on_reset);
400 if (!hvt) {
401 pr_warn("VSS: Failed to initialize transport\n");
402 return -EFAULT;
403 }
404
405 return 0;
406 }
407
hv_vss_cancel_work(void)408 static void hv_vss_cancel_work(void)
409 {
410 cancel_delayed_work_sync(&vss_timeout_work);
411 cancel_work_sync(&vss_handle_request_work);
412 }
413
hv_vss_pre_suspend(void)414 int hv_vss_pre_suspend(void)
415 {
416 struct vmbus_channel *channel = vss_transaction.recv_channel;
417 struct hv_vss_msg *vss_msg;
418
419 /*
420 * Fake a THAW message for the user space daemon in case the daemon
421 * has frozen the file systems. It doesn't matter if there is already
422 * a message pending to be delivered to the user space since we force
423 * vss_transaction.state to be HVUTIL_READY, so the user space daemon's
424 * write() will fail with EINVAL (see vss_on_msg()), and the daemon
425 * will reset the device by closing and re-opening it.
426 */
427 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
428 if (!vss_msg)
429 return -ENOMEM;
430
431 tasklet_disable(&channel->callback_event);
432
433 vss_msg->vss_hdr.operation = VSS_OP_THAW;
434
435 /* Cancel any possible pending work. */
436 hv_vss_cancel_work();
437
438 /* We don't care about the return value. */
439 hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
440
441 kfree(vss_msg);
442
443 vss_transaction.state = HVUTIL_READY;
444
445 /* tasklet_enable() will be called in hv_vss_pre_resume(). */
446 return 0;
447 }
448
hv_vss_pre_resume(void)449 int hv_vss_pre_resume(void)
450 {
451 struct vmbus_channel *channel = vss_transaction.recv_channel;
452
453 tasklet_enable(&channel->callback_event);
454
455 return 0;
456 }
457
hv_vss_deinit(void)458 void hv_vss_deinit(void)
459 {
460 vss_transaction.state = HVUTIL_DEVICE_DYING;
461
462 hv_vss_cancel_work();
463
464 hvutil_transport_destroy(hvt);
465 }
466