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96dd86fa S |
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 | ||
28 | ||
29 | /* | |
30 | * Global state maintained for transaction that is being processed. | |
31 | * Note that only one transaction can be active at any point in time. | |
32 | * | |
33 | * This state is set when we receive a request from the host; we | |
34 | * cleanup this state when the transaction is completed - when we respond | |
35 | * to the host with the key value. | |
36 | */ | |
37 | ||
38 | static struct { | |
39 | bool active; /* transaction status - active or not */ | |
40 | int recv_len; /* number of bytes received. */ | |
41 | struct vmbus_channel *recv_channel; /* chn we got the request */ | |
42 | u64 recv_req_id; /* request ID. */ | |
43 | struct hv_vss_msg *msg; /* current message */ | |
44 | } vss_transaction; | |
45 | ||
46 | ||
47 | static void vss_respond_to_host(int error); | |
48 | ||
49 | static struct cb_id vss_id = { CN_VSS_IDX, CN_VSS_VAL }; | |
50 | static const char vss_name[] = "vss_kernel_module"; | |
51 | static __u8 *recv_buffer; | |
52 | ||
53 | static void vss_send_op(struct work_struct *dummy); | |
54 | static DECLARE_WORK(vss_send_op_work, vss_send_op); | |
55 | ||
56 | /* | |
57 | * Callback when data is received from user mode. | |
58 | */ | |
59 | ||
60 | static void | |
61 | vss_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp) | |
62 | { | |
63 | struct hv_vss_msg *vss_msg; | |
64 | ||
65 | vss_msg = (struct hv_vss_msg *)msg->data; | |
66 | ||
67 | if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER) { | |
68 | pr_info("VSS daemon registered\n"); | |
69 | vss_transaction.active = false; | |
70 | if (vss_transaction.recv_channel != NULL) | |
71 | hv_vss_onchannelcallback(vss_transaction.recv_channel); | |
72 | return; | |
73 | ||
74 | } | |
75 | vss_respond_to_host(vss_msg->error); | |
76 | } | |
77 | ||
78 | ||
79 | static void vss_send_op(struct work_struct *dummy) | |
80 | { | |
81 | int op = vss_transaction.msg->vss_hdr.operation; | |
82 | struct cn_msg *msg; | |
83 | struct hv_vss_msg *vss_msg; | |
84 | ||
85 | msg = kzalloc(sizeof(*msg) + sizeof(*vss_msg), GFP_ATOMIC); | |
86 | if (!msg) | |
87 | return; | |
88 | ||
89 | vss_msg = (struct hv_vss_msg *)msg->data; | |
90 | ||
91 | msg->id.idx = CN_VSS_IDX; | |
92 | msg->id.val = CN_VSS_VAL; | |
93 | ||
94 | vss_msg->vss_hdr.operation = op; | |
95 | msg->len = sizeof(struct hv_vss_msg); | |
96 | ||
97 | cn_netlink_send(msg, 0, GFP_ATOMIC); | |
98 | kfree(msg); | |
99 | ||
100 | return; | |
101 | } | |
102 | ||
103 | /* | |
104 | * Send a response back to the host. | |
105 | */ | |
106 | ||
107 | static void | |
108 | vss_respond_to_host(int error) | |
109 | { | |
110 | struct icmsg_hdr *icmsghdrp; | |
111 | u32 buf_len; | |
112 | struct vmbus_channel *channel; | |
113 | u64 req_id; | |
114 | ||
115 | /* | |
116 | * If a transaction is not active; log and return. | |
117 | */ | |
118 | ||
119 | if (!vss_transaction.active) { | |
120 | /* | |
121 | * This is a spurious call! | |
122 | */ | |
123 | pr_warn("VSS: Transaction not active\n"); | |
124 | return; | |
125 | } | |
126 | /* | |
127 | * Copy the global state for completing the transaction. Note that | |
128 | * only one transaction can be active at a time. | |
129 | */ | |
130 | ||
131 | buf_len = vss_transaction.recv_len; | |
132 | channel = vss_transaction.recv_channel; | |
133 | req_id = vss_transaction.recv_req_id; | |
134 | vss_transaction.active = false; | |
135 | ||
136 | icmsghdrp = (struct icmsg_hdr *) | |
137 | &recv_buffer[sizeof(struct vmbuspipe_hdr)]; | |
138 | ||
139 | if (channel->onchannel_callback == NULL) | |
140 | /* | |
141 | * We have raced with util driver being unloaded; | |
142 | * silently return. | |
143 | */ | |
144 | return; | |
145 | ||
146 | icmsghdrp->status = error; | |
147 | ||
148 | icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE; | |
149 | ||
150 | vmbus_sendpacket(channel, recv_buffer, buf_len, req_id, | |
151 | VM_PKT_DATA_INBAND, 0); | |
152 | ||
153 | } | |
154 | ||
155 | /* | |
156 | * This callback is invoked when we get a VSS message from the host. | |
157 | * The host ensures that only one VSS transaction can be active at a time. | |
158 | */ | |
159 | ||
160 | void hv_vss_onchannelcallback(void *context) | |
161 | { | |
162 | struct vmbus_channel *channel = context; | |
163 | u32 recvlen; | |
164 | u64 requestid; | |
165 | struct hv_vss_msg *vss_msg; | |
166 | ||
167 | ||
168 | struct icmsg_hdr *icmsghdrp; | |
169 | struct icmsg_negotiate *negop = NULL; | |
170 | ||
171 | if (vss_transaction.active) { | |
172 | /* | |
173 | * We will defer processing this callback once | |
174 | * the current transaction is complete. | |
175 | */ | |
176 | vss_transaction.recv_channel = channel; | |
177 | return; | |
178 | } | |
179 | ||
180 | vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen, | |
181 | &requestid); | |
182 | ||
183 | if (recvlen > 0) { | |
184 | icmsghdrp = (struct icmsg_hdr *)&recv_buffer[ | |
185 | sizeof(struct vmbuspipe_hdr)]; | |
186 | ||
187 | if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) { | |
188 | vmbus_prep_negotiate_resp(icmsghdrp, negop, | |
189 | recv_buffer, MAX_SRV_VER, MAX_SRV_VER); | |
190 | /* | |
191 | * We currently negotiate the highest number the | |
192 | * host has presented. If this version is not | |
193 | * atleast 5.0, reject. | |
194 | */ | |
195 | negop = (struct icmsg_negotiate *)&recv_buffer[ | |
196 | sizeof(struct vmbuspipe_hdr) + | |
197 | sizeof(struct icmsg_hdr)]; | |
198 | ||
199 | if (negop->icversion_data[1].major < 5) | |
200 | negop->icframe_vercnt = 0; | |
201 | } else { | |
202 | vss_msg = (struct hv_vss_msg *)&recv_buffer[ | |
203 | sizeof(struct vmbuspipe_hdr) + | |
204 | sizeof(struct icmsg_hdr)]; | |
205 | ||
206 | /* | |
207 | * Stash away this global state for completing the | |
208 | * transaction; note transactions are serialized. | |
209 | */ | |
210 | ||
211 | vss_transaction.recv_len = recvlen; | |
212 | vss_transaction.recv_channel = channel; | |
213 | vss_transaction.recv_req_id = requestid; | |
214 | vss_transaction.active = true; | |
215 | vss_transaction.msg = (struct hv_vss_msg *)vss_msg; | |
216 | ||
217 | switch (vss_msg->vss_hdr.operation) { | |
218 | /* | |
219 | * Initiate a "freeze/thaw" | |
220 | * operation in the guest. | |
221 | * We respond to the host once | |
222 | * the operation is complete. | |
223 | * | |
224 | * We send the message to the | |
225 | * user space daemon and the | |
226 | * operation is performed in | |
227 | * the daemon. | |
228 | */ | |
229 | case VSS_OP_FREEZE: | |
230 | case VSS_OP_THAW: | |
231 | schedule_work(&vss_send_op_work); | |
232 | return; | |
233 | ||
234 | case VSS_OP_HOT_BACKUP: | |
235 | vss_msg->vss_cf.flags = | |
236 | VSS_HBU_NO_AUTO_RECOVERY; | |
237 | vss_respond_to_host(0); | |
238 | return; | |
239 | ||
240 | case VSS_OP_GET_DM_INFO: | |
241 | vss_msg->dm_info.flags = 0; | |
242 | vss_respond_to_host(0); | |
243 | return; | |
244 | ||
245 | default: | |
246 | vss_respond_to_host(0); | |
247 | return; | |
248 | ||
249 | } | |
250 | ||
251 | } | |
252 | ||
253 | icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | |
254 | | ICMSGHDRFLAG_RESPONSE; | |
255 | ||
256 | vmbus_sendpacket(channel, recv_buffer, | |
257 | recvlen, requestid, | |
258 | VM_PKT_DATA_INBAND, 0); | |
259 | } | |
260 | ||
261 | } | |
262 | ||
263 | int | |
264 | hv_vss_init(struct hv_util_service *srv) | |
265 | { | |
266 | int err; | |
267 | ||
268 | err = cn_add_callback(&vss_id, vss_name, vss_cn_callback); | |
269 | if (err) | |
270 | return err; | |
271 | recv_buffer = srv->recv_buffer; | |
272 | ||
273 | /* | |
274 | * When this driver loads, the user level daemon that | |
275 | * processes the host requests may not yet be running. | |
276 | * Defer processing channel callbacks until the daemon | |
277 | * has registered. | |
278 | */ | |
279 | vss_transaction.active = true; | |
280 | return 0; | |
281 | } | |
282 | ||
283 | void hv_vss_deinit(void) | |
284 | { | |
285 | cn_del_callback(&vss_id); | |
286 | cancel_work_sync(&vss_send_op_work); | |
287 | } |