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 static struct completion release_event;
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
vss_poll_wrapper(void * channel)77 static void vss_poll_wrapper(void *channel)
78 {
79 /* Transaction is finished, reset the state here to avoid races. */
80 vss_transaction.state = HVUTIL_READY;
81 hv_vss_onchannelcallback(channel);
82 }
83
84 /*
85 * Callback when data is received from user mode.
86 */
87
vss_timeout_func(struct work_struct * dummy)88 static void vss_timeout_func(struct work_struct *dummy)
89 {
90 /*
91 * Timeout waiting for userspace component to reply happened.
92 */
93 pr_warn("VSS: timeout waiting for daemon to reply\n");
94 vss_respond_to_host(HV_E_FAIL);
95
96 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
97 }
98
vss_handle_handshake(struct hv_vss_msg * vss_msg)99 static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
100 {
101 u32 our_ver = VSS_OP_REGISTER1;
102
103 switch (vss_msg->vss_hdr.operation) {
104 case VSS_OP_REGISTER:
105 /* Daemon doesn't expect us to reply */
106 dm_reg_value = VSS_OP_REGISTER;
107 break;
108 case VSS_OP_REGISTER1:
109 /* Daemon expects us to reply with our own version*/
110 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver)))
111 return -EFAULT;
112 dm_reg_value = VSS_OP_REGISTER1;
113 break;
114 default:
115 return -EINVAL;
116 }
117 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
118 pr_debug("VSS: userspace daemon ver. %d registered\n", dm_reg_value);
119 return 0;
120 }
121
vss_on_msg(void * msg,int len)122 static int vss_on_msg(void *msg, int len)
123 {
124 struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;
125
126 if (len != sizeof(*vss_msg))
127 return -EINVAL;
128
129 if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||
130 vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
131 /*
132 * Don't process registration messages if we're in the middle
133 * of a transaction processing.
134 */
135 if (vss_transaction.state > HVUTIL_READY)
136 return -EINVAL;
137 return vss_handle_handshake(vss_msg);
138 } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
139 vss_transaction.state = HVUTIL_USERSPACE_RECV;
140 if (cancel_delayed_work_sync(&vss_timeout_work)) {
141 vss_respond_to_host(vss_msg->error);
142 /* Transaction is finished, reset the state. */
143 hv_poll_channel(vss_transaction.recv_channel,
144 vss_poll_wrapper);
145 }
146 } else {
147 /* This is a spurious call! */
148 pr_warn("VSS: Transaction not active\n");
149 return -EINVAL;
150 }
151 return 0;
152 }
153
154
vss_send_op(struct work_struct * dummy)155 static void vss_send_op(struct work_struct *dummy)
156 {
157 int op = vss_transaction.msg->vss_hdr.operation;
158 int rc;
159 struct hv_vss_msg *vss_msg;
160
161 /* The transaction state is wrong. */
162 if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED)
163 return;
164
165 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
166 if (!vss_msg)
167 return;
168
169 vss_msg->vss_hdr.operation = op;
170
171 vss_transaction.state = HVUTIL_USERSPACE_REQ;
172 rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg));
173 if (rc) {
174 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
175 if (cancel_delayed_work_sync(&vss_timeout_work)) {
176 vss_respond_to_host(HV_E_FAIL);
177 vss_transaction.state = HVUTIL_READY;
178 }
179 }
180
181 kfree(vss_msg);
182
183 return;
184 }
185
186 /*
187 * Send a response back to the host.
188 */
189
190 static void
vss_respond_to_host(int error)191 vss_respond_to_host(int error)
192 {
193 struct icmsg_hdr *icmsghdrp;
194 u32 buf_len;
195 struct vmbus_channel *channel;
196 u64 req_id;
197
198 /*
199 * Copy the global state for completing the transaction. Note that
200 * only one transaction can be active at a time.
201 */
202
203 buf_len = vss_transaction.recv_len;
204 channel = vss_transaction.recv_channel;
205 req_id = vss_transaction.recv_req_id;
206
207 icmsghdrp = (struct icmsg_hdr *)
208 &recv_buffer[sizeof(struct vmbuspipe_hdr)];
209
210 if (channel->onchannel_callback == NULL)
211 /*
212 * We have raced with util driver being unloaded;
213 * silently return.
214 */
215 return;
216
217 icmsghdrp->status = error;
218
219 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
220
221 vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
222 VM_PKT_DATA_INBAND, 0);
223
224 }
225
226 /*
227 * This callback is invoked when we get a VSS message from the host.
228 * The host ensures that only one VSS transaction can be active at a time.
229 */
230
hv_vss_onchannelcallback(void * context)231 void hv_vss_onchannelcallback(void *context)
232 {
233 struct vmbus_channel *channel = context;
234 u32 recvlen;
235 u64 requestid;
236 struct hv_vss_msg *vss_msg;
237
238
239 struct icmsg_hdr *icmsghdrp;
240 struct icmsg_negotiate *negop = NULL;
241
242 if (vss_transaction.state > HVUTIL_READY)
243 return;
244
245 vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
246 &requestid);
247
248 if (recvlen > 0) {
249 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
250 sizeof(struct vmbuspipe_hdr)];
251
252 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
253 vmbus_prep_negotiate_resp(icmsghdrp, negop,
254 recv_buffer, UTIL_FW_VERSION,
255 VSS_VERSION);
256 } else {
257 vss_msg = (struct hv_vss_msg *)&recv_buffer[
258 sizeof(struct vmbuspipe_hdr) +
259 sizeof(struct icmsg_hdr)];
260
261 /*
262 * Stash away this global state for completing the
263 * transaction; note transactions are serialized.
264 */
265
266 vss_transaction.recv_len = recvlen;
267 vss_transaction.recv_req_id = requestid;
268 vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
269
270 switch (vss_msg->vss_hdr.operation) {
271 /*
272 * Initiate a "freeze/thaw"
273 * operation in the guest.
274 * We respond to the host once
275 * the operation is complete.
276 *
277 * We send the message to the
278 * user space daemon and the
279 * operation is performed in
280 * the daemon.
281 */
282 case VSS_OP_FREEZE:
283 case VSS_OP_THAW:
284 if (vss_transaction.state < HVUTIL_READY) {
285 /* Userspace is not registered yet */
286 vss_respond_to_host(HV_E_FAIL);
287 return;
288 }
289 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
290 schedule_work(&vss_send_op_work);
291 schedule_delayed_work(&vss_timeout_work,
292 VSS_USERSPACE_TIMEOUT);
293 return;
294
295 case VSS_OP_HOT_BACKUP:
296 vss_msg->vss_cf.flags =
297 VSS_HBU_NO_AUTO_RECOVERY;
298 vss_respond_to_host(0);
299 return;
300
301 case VSS_OP_GET_DM_INFO:
302 vss_msg->dm_info.flags = 0;
303 vss_respond_to_host(0);
304 return;
305
306 default:
307 vss_respond_to_host(0);
308 return;
309
310 }
311
312 }
313
314 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
315 | ICMSGHDRFLAG_RESPONSE;
316
317 vmbus_sendpacket(channel, recv_buffer,
318 recvlen, requestid,
319 VM_PKT_DATA_INBAND, 0);
320 }
321
322 }
323
vss_on_reset(void)324 static void vss_on_reset(void)
325 {
326 if (cancel_delayed_work_sync(&vss_timeout_work))
327 vss_respond_to_host(HV_E_FAIL);
328 vss_transaction.state = HVUTIL_DEVICE_INIT;
329 complete(&release_event);
330 }
331
332 int
hv_vss_init(struct hv_util_service * srv)333 hv_vss_init(struct hv_util_service *srv)
334 {
335 init_completion(&release_event);
336 if (vmbus_proto_version < VERSION_WIN8_1) {
337 pr_warn("Integration service 'Backup (volume snapshot)'"
338 " not supported on this host version.\n");
339 return -ENOTSUPP;
340 }
341 recv_buffer = srv->recv_buffer;
342 vss_transaction.recv_channel = srv->channel;
343
344 /*
345 * When this driver loads, the user level daemon that
346 * processes the host requests may not yet be running.
347 * Defer processing channel callbacks until the daemon
348 * has registered.
349 */
350 vss_transaction.state = HVUTIL_DEVICE_INIT;
351
352 hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
353 vss_on_msg, vss_on_reset);
354 if (!hvt)
355 return -EFAULT;
356
357 return 0;
358 }
359
hv_vss_deinit(void)360 void hv_vss_deinit(void)
361 {
362 vss_transaction.state = HVUTIL_DEVICE_DYING;
363 cancel_delayed_work_sync(&vss_timeout_work);
364 cancel_work_sync(&vss_send_op_work);
365 hvutil_transport_destroy(hvt);
366 wait_for_completion(&release_event);
367 }
368