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
vss_poll_wrapper(void * channel)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
vss_timeout_func(struct work_struct * dummy)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
vss_register_done(void)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
vss_handle_handshake(struct hv_vss_msg * vss_msg)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
vss_on_msg(void * msg,int len)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
vss_send_op(void)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
vss_handle_request(struct work_struct * dummy)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
vss_respond_to_host(int error)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
hv_vss_onchannelcallback(void * context)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
vss_on_reset(void)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
hv_vss_init(struct hv_util_service * srv)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
hv_vss_deinit(void)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