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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
50static 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
59static void vss_respond_to_host(int error);
60
61/*
62 * This state maintains the version number registered by the daemon.
63 */
64static int dm_reg_value;
65
66static const char vss_devname[] = "vmbus/hv_vss";
67static __u8 *recv_buffer;
68static struct hvutil_transport *hvt;
69
70static void vss_send_op(struct work_struct *dummy);
71static void vss_timeout_func(struct work_struct *dummy);
72
73static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
74static DECLARE_WORK(vss_send_op_work, vss_send_op);
75
76static void vss_poll_wrapper(void *channel)
77{
78 /* Transaction is finished, reset the state here to avoid races. */
79 vss_transaction.state = HVUTIL_READY;
80 hv_vss_onchannelcallback(channel);
81}
82
83/*
84 * Callback when data is received from user mode.
85 */
86
87static void vss_timeout_func(struct work_struct *dummy)
88{
89 /*
90 * Timeout waiting for userspace component to reply happened.
91 */
92 pr_warn("VSS: timeout waiting for daemon to reply\n");
93 vss_respond_to_host(HV_E_FAIL);
94
95 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
96}
97
98static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
99{
100 u32 our_ver = VSS_OP_REGISTER1;
101
102 switch (vss_msg->vss_hdr.operation) {
103 case VSS_OP_REGISTER:
104 /* Daemon doesn't expect us to reply */
105 dm_reg_value = VSS_OP_REGISTER;
106 break;
107 case VSS_OP_REGISTER1:
108 /* Daemon expects us to reply with our own version*/
109 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver)))
110 return -EFAULT;
111 dm_reg_value = VSS_OP_REGISTER1;
112 break;
113 default:
114 return -EINVAL;
115 }
116 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
117 pr_debug("VSS: userspace daemon ver. %d registered\n", dm_reg_value);
118 return 0;
119}
120
121static int vss_on_msg(void *msg, int len)
122{
123 struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;
124
125 if (len != sizeof(*vss_msg))
126 return -EINVAL;
127
128 if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||
129 vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
130 /*
131 * Don't process registration messages if we're in the middle
132 * of a transaction processing.
133 */
134 if (vss_transaction.state > HVUTIL_READY)
135 return -EINVAL;
136 return vss_handle_handshake(vss_msg);
137 } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
138 vss_transaction.state = HVUTIL_USERSPACE_RECV;
139 if (cancel_delayed_work_sync(&vss_timeout_work)) {
140 vss_respond_to_host(vss_msg->error);
141 /* Transaction is finished, reset the state. */
142 hv_poll_channel(vss_transaction.recv_channel,
143 vss_poll_wrapper);
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
154static 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
189static void
190vss_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
230void 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 return;
243
244 vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
245 &requestid);
246
247 if (recvlen > 0) {
248 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
249 sizeof(struct vmbuspipe_hdr)];
250
251 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
252 vmbus_prep_negotiate_resp(icmsghdrp, negop,
253 recv_buffer, UTIL_FW_VERSION,
254 VSS_VERSION);
255 } else {
256 vss_msg = (struct hv_vss_msg *)&recv_buffer[
257 sizeof(struct vmbuspipe_hdr) +
258 sizeof(struct icmsg_hdr)];
259
260 /*
261 * Stash away this global state for completing the
262 * transaction; note transactions are serialized.
263 */
264
265 vss_transaction.recv_len = recvlen;
266 vss_transaction.recv_req_id = requestid;
267 vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
268
269 switch (vss_msg->vss_hdr.operation) {
270 /*
271 * Initiate a "freeze/thaw"
272 * operation in the guest.
273 * We respond to the host once
274 * the operation is complete.
275 *
276 * We send the message to the
277 * user space daemon and the
278 * operation is performed in
279 * the daemon.
280 */
281 case VSS_OP_FREEZE:
282 case VSS_OP_THAW:
283 if (vss_transaction.state < HVUTIL_READY) {
284 /* Userspace is not registered yet */
285 vss_respond_to_host(HV_E_FAIL);
286 return;
287 }
288 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
289 schedule_work(&vss_send_op_work);
290 schedule_delayed_work(&vss_timeout_work,
291 VSS_USERSPACE_TIMEOUT);
292 return;
293
294 case VSS_OP_HOT_BACKUP:
295 vss_msg->vss_cf.flags =
296 VSS_HBU_NO_AUTO_RECOVERY;
297 vss_respond_to_host(0);
298 return;
299
300 case VSS_OP_GET_DM_INFO:
301 vss_msg->dm_info.flags = 0;
302 vss_respond_to_host(0);
303 return;
304
305 default:
306 vss_respond_to_host(0);
307 return;
308
309 }
310
311 }
312
313 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
314 | ICMSGHDRFLAG_RESPONSE;
315
316 vmbus_sendpacket(channel, recv_buffer,
317 recvlen, requestid,
318 VM_PKT_DATA_INBAND, 0);
319 }
320
321}
322
323static void vss_on_reset(void)
324{
325 if (cancel_delayed_work_sync(&vss_timeout_work))
326 vss_respond_to_host(HV_E_FAIL);
327 vss_transaction.state = HVUTIL_DEVICE_INIT;
328}
329
330int
331hv_vss_init(struct hv_util_service *srv)
332{
333 if (vmbus_proto_version < VERSION_WIN8_1) {
334 pr_warn("Integration service 'Backup (volume snapshot)'"
335 " not supported on this host version.\n");
336 return -ENOTSUPP;
337 }
338 recv_buffer = srv->recv_buffer;
339 vss_transaction.recv_channel = srv->channel;
340
341 /*
342 * When this driver loads, the user level daemon that
343 * processes the host requests may not yet be running.
344 * Defer processing channel callbacks until the daemon
345 * has registered.
346 */
347 vss_transaction.state = HVUTIL_DEVICE_INIT;
348
349 hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
350 vss_on_msg, vss_on_reset);
351 if (!hvt)
352 return -EFAULT;
353
354 return 0;
355}
356
357void hv_vss_deinit(void)
358{
359 vss_transaction.state = HVUTIL_DEVICE_DYING;
360 cancel_delayed_work_sync(&vss_timeout_work);
361 cancel_work_sync(&vss_send_op_work);
362 hvutil_transport_destroy(hvt);
363}