2 * An implementation of host initiated guest snapshot.
5 * Copyright (C) 2013, Microsoft, Inc.
6 * Author : K. Y. Srinivasan <kys@microsoft.com>
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.
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
19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
29 #define VSS_VERSION (VSS_MAJOR << 16 | VSS_MINOR)
31 #define VSS_USERSPACE_TIMEOUT (msecs_to_jiffies(10 * 1000))
34 * Global state maintained for transaction that is being processed.
35 * Note that only one transaction can be active at any point in time.
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.
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 */
51 static void vss_respond_to_host(int error
);
53 static struct cb_id vss_id
= { CN_VSS_IDX
, CN_VSS_VAL
};
54 static const char vss_name
[] = "vss_kernel_module";
55 static __u8
*recv_buffer
;
57 static void vss_send_op(struct work_struct
*dummy
);
58 static void vss_timeout_func(struct work_struct
*dummy
);
60 static DECLARE_DELAYED_WORK(vss_timeout_work
, vss_timeout_func
);
61 static DECLARE_WORK(vss_send_op_work
, vss_send_op
);
64 * Callback when data is received from user mode.
67 static void vss_timeout_func(struct work_struct
*dummy
)
70 * Timeout waiting for userspace component to reply happened.
72 pr_warn("VSS: timeout waiting for daemon to reply\n");
73 vss_respond_to_host(HV_E_FAIL
);
77 vss_cn_callback(struct cn_msg
*msg
, struct netlink_skb_parms
*nsp
)
79 struct hv_vss_msg
*vss_msg
;
81 vss_msg
= (struct hv_vss_msg
*)msg
->data
;
83 if (vss_msg
->vss_hdr
.operation
== VSS_OP_REGISTER
) {
84 pr_info("VSS daemon registered\n");
85 vss_transaction
.active
= false;
86 if (vss_transaction
.recv_channel
!= NULL
)
87 hv_vss_onchannelcallback(vss_transaction
.recv_channel
);
91 if (cancel_delayed_work_sync(&vss_timeout_work
))
92 vss_respond_to_host(vss_msg
->error
);
96 static void vss_send_op(struct work_struct
*dummy
)
98 int op
= vss_transaction
.msg
->vss_hdr
.operation
;
101 struct hv_vss_msg
*vss_msg
;
103 msg
= kzalloc(sizeof(*msg
) + sizeof(*vss_msg
), GFP_ATOMIC
);
107 vss_msg
= (struct hv_vss_msg
*)msg
->data
;
109 msg
->id
.idx
= CN_VSS_IDX
;
110 msg
->id
.val
= CN_VSS_VAL
;
112 vss_msg
->vss_hdr
.operation
= op
;
113 msg
->len
= sizeof(struct hv_vss_msg
);
115 rc
= cn_netlink_send(msg
, 0, 0, GFP_ATOMIC
);
117 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc
);
118 if (cancel_delayed_work_sync(&vss_timeout_work
))
119 vss_respond_to_host(HV_E_FAIL
);
127 * Send a response back to the host.
131 vss_respond_to_host(int error
)
133 struct icmsg_hdr
*icmsghdrp
;
135 struct vmbus_channel
*channel
;
139 * If a transaction is not active; log and return.
142 if (!vss_transaction
.active
) {
144 * This is a spurious call!
146 pr_warn("VSS: Transaction not active\n");
150 * Copy the global state for completing the transaction. Note that
151 * only one transaction can be active at a time.
154 buf_len
= vss_transaction
.recv_len
;
155 channel
= vss_transaction
.recv_channel
;
156 req_id
= vss_transaction
.recv_req_id
;
157 vss_transaction
.active
= false;
159 icmsghdrp
= (struct icmsg_hdr
*)
160 &recv_buffer
[sizeof(struct vmbuspipe_hdr
)];
162 if (channel
->onchannel_callback
== NULL
)
164 * We have raced with util driver being unloaded;
169 icmsghdrp
->status
= error
;
171 icmsghdrp
->icflags
= ICMSGHDRFLAG_TRANSACTION
| ICMSGHDRFLAG_RESPONSE
;
173 vmbus_sendpacket(channel
, recv_buffer
, buf_len
, req_id
,
174 VM_PKT_DATA_INBAND
, 0);
179 * This callback is invoked when we get a VSS message from the host.
180 * The host ensures that only one VSS transaction can be active at a time.
183 void hv_vss_onchannelcallback(void *context
)
185 struct vmbus_channel
*channel
= context
;
188 struct hv_vss_msg
*vss_msg
;
191 struct icmsg_hdr
*icmsghdrp
;
192 struct icmsg_negotiate
*negop
= NULL
;
194 if (vss_transaction
.active
) {
196 * We will defer processing this callback once
197 * the current transaction is complete.
199 vss_transaction
.recv_channel
= channel
;
203 vmbus_recvpacket(channel
, recv_buffer
, PAGE_SIZE
* 2, &recvlen
,
207 icmsghdrp
= (struct icmsg_hdr
*)&recv_buffer
[
208 sizeof(struct vmbuspipe_hdr
)];
210 if (icmsghdrp
->icmsgtype
== ICMSGTYPE_NEGOTIATE
) {
211 vmbus_prep_negotiate_resp(icmsghdrp
, negop
,
212 recv_buffer
, UTIL_FW_VERSION
,
215 vss_msg
= (struct hv_vss_msg
*)&recv_buffer
[
216 sizeof(struct vmbuspipe_hdr
) +
217 sizeof(struct icmsg_hdr
)];
220 * Stash away this global state for completing the
221 * transaction; note transactions are serialized.
224 vss_transaction
.recv_len
= recvlen
;
225 vss_transaction
.recv_channel
= channel
;
226 vss_transaction
.recv_req_id
= requestid
;
227 vss_transaction
.active
= true;
228 vss_transaction
.msg
= (struct hv_vss_msg
*)vss_msg
;
230 switch (vss_msg
->vss_hdr
.operation
) {
232 * Initiate a "freeze/thaw"
233 * operation in the guest.
234 * We respond to the host once
235 * the operation is complete.
237 * We send the message to the
238 * user space daemon and the
239 * operation is performed in
244 schedule_work(&vss_send_op_work
);
245 schedule_delayed_work(&vss_timeout_work
,
246 VSS_USERSPACE_TIMEOUT
);
249 case VSS_OP_HOT_BACKUP
:
250 vss_msg
->vss_cf
.flags
=
251 VSS_HBU_NO_AUTO_RECOVERY
;
252 vss_respond_to_host(0);
255 case VSS_OP_GET_DM_INFO
:
256 vss_msg
->dm_info
.flags
= 0;
257 vss_respond_to_host(0);
261 vss_respond_to_host(0);
268 icmsghdrp
->icflags
= ICMSGHDRFLAG_TRANSACTION
269 | ICMSGHDRFLAG_RESPONSE
;
271 vmbus_sendpacket(channel
, recv_buffer
,
273 VM_PKT_DATA_INBAND
, 0);
279 hv_vss_init(struct hv_util_service
*srv
)
283 err
= cn_add_callback(&vss_id
, vss_name
, vss_cn_callback
);
286 recv_buffer
= srv
->recv_buffer
;
289 * When this driver loads, the user level daemon that
290 * processes the host requests may not yet be running.
291 * Defer processing channel callbacks until the daemon
294 vss_transaction
.active
= true;
298 void hv_vss_deinit(void)
300 cn_del_callback(&vss_id
);
301 cancel_delayed_work_sync(&vss_timeout_work
);
302 cancel_work_sync(&vss_send_op_work
);
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