blob: 0c354622437681d1b6dd157f718bb27cf8dbdbed [file] [log] [blame]
K. Y. Srinivasan96dd86f2013-03-15 12:30:06 -07001/*
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
K. Y. Srinivasan67413352013-07-02 10:31:30 -070027#define VSS_MAJOR 5
28#define VSS_MINOR 0
K. Y. Srinivasan3a491602013-09-06 11:49:56 -070029#define VSS_VERSION (VSS_MAJOR << 16 | VSS_MINOR)
K. Y. Srinivasan67413352013-07-02 10:31:30 -070030
K. Y. Srinivasan96dd86f2013-03-15 12:30:06 -070031
32
33/*
34 * Global state maintained for transaction that is being processed.
35 * Note that only one transaction can be active at any point in time.
36 *
37 * This state is set when we receive a request from the host; we
38 * cleanup this state when the transaction is completed - when we respond
39 * to the host with the key value.
40 */
41
42static struct {
43 bool active; /* transaction status - active or not */
44 int recv_len; /* number of bytes received. */
45 struct vmbus_channel *recv_channel; /* chn we got the request */
46 u64 recv_req_id; /* request ID. */
47 struct hv_vss_msg *msg; /* current message */
48} vss_transaction;
49
50
51static void vss_respond_to_host(int error);
52
53static struct cb_id vss_id = { CN_VSS_IDX, CN_VSS_VAL };
54static const char vss_name[] = "vss_kernel_module";
55static __u8 *recv_buffer;
56
57static void vss_send_op(struct work_struct *dummy);
58static DECLARE_WORK(vss_send_op_work, vss_send_op);
59
60/*
61 * Callback when data is received from user mode.
62 */
63
64static void
65vss_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
66{
67 struct hv_vss_msg *vss_msg;
68
69 vss_msg = (struct hv_vss_msg *)msg->data;
70
71 if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER) {
72 pr_info("VSS daemon registered\n");
73 vss_transaction.active = false;
74 if (vss_transaction.recv_channel != NULL)
75 hv_vss_onchannelcallback(vss_transaction.recv_channel);
76 return;
77
78 }
79 vss_respond_to_host(vss_msg->error);
80}
81
82
83static void vss_send_op(struct work_struct *dummy)
84{
85 int op = vss_transaction.msg->vss_hdr.operation;
86 struct cn_msg *msg;
87 struct hv_vss_msg *vss_msg;
88
89 msg = kzalloc(sizeof(*msg) + sizeof(*vss_msg), GFP_ATOMIC);
90 if (!msg)
91 return;
92
93 vss_msg = (struct hv_vss_msg *)msg->data;
94
95 msg->id.idx = CN_VSS_IDX;
96 msg->id.val = CN_VSS_VAL;
97
98 vss_msg->vss_hdr.operation = op;
99 msg->len = sizeof(struct hv_vss_msg);
100
101 cn_netlink_send(msg, 0, GFP_ATOMIC);
102 kfree(msg);
103
104 return;
105}
106
107/*
108 * Send a response back to the host.
109 */
110
111static void
112vss_respond_to_host(int error)
113{
114 struct icmsg_hdr *icmsghdrp;
115 u32 buf_len;
116 struct vmbus_channel *channel;
117 u64 req_id;
118
119 /*
120 * If a transaction is not active; log and return.
121 */
122
123 if (!vss_transaction.active) {
124 /*
125 * This is a spurious call!
126 */
127 pr_warn("VSS: Transaction not active\n");
128 return;
129 }
130 /*
131 * Copy the global state for completing the transaction. Note that
132 * only one transaction can be active at a time.
133 */
134
135 buf_len = vss_transaction.recv_len;
136 channel = vss_transaction.recv_channel;
137 req_id = vss_transaction.recv_req_id;
138 vss_transaction.active = false;
139
140 icmsghdrp = (struct icmsg_hdr *)
141 &recv_buffer[sizeof(struct vmbuspipe_hdr)];
142
143 if (channel->onchannel_callback == NULL)
144 /*
145 * We have raced with util driver being unloaded;
146 * silently return.
147 */
148 return;
149
150 icmsghdrp->status = error;
151
152 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
153
154 vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
155 VM_PKT_DATA_INBAND, 0);
156
157}
158
159/*
160 * This callback is invoked when we get a VSS message from the host.
161 * The host ensures that only one VSS transaction can be active at a time.
162 */
163
164void hv_vss_onchannelcallback(void *context)
165{
166 struct vmbus_channel *channel = context;
167 u32 recvlen;
168 u64 requestid;
169 struct hv_vss_msg *vss_msg;
170
171
172 struct icmsg_hdr *icmsghdrp;
173 struct icmsg_negotiate *negop = NULL;
174
175 if (vss_transaction.active) {
176 /*
177 * We will defer processing this callback once
178 * the current transaction is complete.
179 */
180 vss_transaction.recv_channel = channel;
181 return;
182 }
183
184 vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
185 &requestid);
186
187 if (recvlen > 0) {
188 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
189 sizeof(struct vmbuspipe_hdr)];
190
191 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
192 vmbus_prep_negotiate_resp(icmsghdrp, negop,
K. Y. Srinivasan3a491602013-09-06 11:49:56 -0700193 recv_buffer, UTIL_FW_VERSION,
194 VSS_VERSION);
K. Y. Srinivasan96dd86f2013-03-15 12:30:06 -0700195 } else {
196 vss_msg = (struct hv_vss_msg *)&recv_buffer[
197 sizeof(struct vmbuspipe_hdr) +
198 sizeof(struct icmsg_hdr)];
199
200 /*
201 * Stash away this global state for completing the
202 * transaction; note transactions are serialized.
203 */
204
205 vss_transaction.recv_len = recvlen;
206 vss_transaction.recv_channel = channel;
207 vss_transaction.recv_req_id = requestid;
208 vss_transaction.active = true;
209 vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
210
211 switch (vss_msg->vss_hdr.operation) {
212 /*
213 * Initiate a "freeze/thaw"
214 * operation in the guest.
215 * We respond to the host once
216 * the operation is complete.
217 *
218 * We send the message to the
219 * user space daemon and the
220 * operation is performed in
221 * the daemon.
222 */
223 case VSS_OP_FREEZE:
224 case VSS_OP_THAW:
225 schedule_work(&vss_send_op_work);
226 return;
227
228 case VSS_OP_HOT_BACKUP:
229 vss_msg->vss_cf.flags =
230 VSS_HBU_NO_AUTO_RECOVERY;
231 vss_respond_to_host(0);
232 return;
233
234 case VSS_OP_GET_DM_INFO:
235 vss_msg->dm_info.flags = 0;
236 vss_respond_to_host(0);
237 return;
238
239 default:
240 vss_respond_to_host(0);
241 return;
242
243 }
244
245 }
246
247 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
248 | ICMSGHDRFLAG_RESPONSE;
249
250 vmbus_sendpacket(channel, recv_buffer,
251 recvlen, requestid,
252 VM_PKT_DATA_INBAND, 0);
253 }
254
255}
256
257int
258hv_vss_init(struct hv_util_service *srv)
259{
260 int err;
261
262 err = cn_add_callback(&vss_id, vss_name, vss_cn_callback);
263 if (err)
264 return err;
265 recv_buffer = srv->recv_buffer;
266
267 /*
268 * When this driver loads, the user level daemon that
269 * processes the host requests may not yet be running.
270 * Defer processing channel callbacks until the daemon
271 * has registered.
272 */
273 vss_transaction.active = true;
274 return 0;
275}
276
277void hv_vss_deinit(void)
278{
279 cn_del_callback(&vss_id);
280 cancel_work_sync(&vss_send_op_work);
281}