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