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>
27 #include "hyperv_vmbus.h"
28 #include "hv_utils_transport.h"
32 #define VSS_VERSION (VSS_MAJOR << 16 | VSS_MINOR)
34 #define VSS_USERSPACE_TIMEOUT (msecs_to_jiffies(10 * 1000))
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.
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
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 */
59 static void vss_respond_to_host(int error);
62 * This state maintains the version number registered by the daemon.
64 static int dm_reg_value;
66 static const char vss_devname[] = "vmbus/hv_vss";
67 static __u8 *recv_buffer;
68 static struct hvutil_transport *hvt;
70 static void vss_send_op(struct work_struct *dummy);
71 static void vss_timeout_func(struct work_struct *dummy);
73 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
74 static DECLARE_WORK(vss_send_op_work, vss_send_op);
76 static void vss_poll_wrapper(void *channel)
78 /* Transaction is finished, reset the state here to avoid races. */
79 vss_transaction.state = HVUTIL_READY;
80 hv_vss_onchannelcallback(channel);
84 * Callback when data is received from user mode.
87 static void vss_timeout_func(struct work_struct *dummy)
90 * Timeout waiting for userspace component to reply happened.
92 pr_warn("VSS: timeout waiting for daemon to reply\n");
93 vss_respond_to_host(HV_E_FAIL);
95 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
98 static void vss_register_done(void)
100 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
101 pr_debug("VSS: userspace daemon registered\n");
104 static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
106 u32 our_ver = VSS_OP_REGISTER1;
108 switch (vss_msg->vss_hdr.operation) {
109 case VSS_OP_REGISTER:
110 /* Daemon doesn't expect us to reply */
111 dm_reg_value = VSS_OP_REGISTER;
113 case VSS_OP_REGISTER1:
114 /* Daemon expects us to reply with our own version */
115 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
118 dm_reg_value = VSS_OP_REGISTER1;
123 pr_debug("VSS: userspace daemon ver. %d connected\n", dm_reg_value);
127 static int vss_on_msg(void *msg, int len)
129 struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;
131 if (len != sizeof(*vss_msg))
134 if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||
135 vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
137 * Don't process registration messages if we're in the middle
138 * of a transaction processing.
140 if (vss_transaction.state > HVUTIL_READY)
142 return vss_handle_handshake(vss_msg);
143 } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
144 vss_transaction.state = HVUTIL_USERSPACE_RECV;
145 if (cancel_delayed_work_sync(&vss_timeout_work)) {
146 vss_respond_to_host(vss_msg->error);
147 /* Transaction is finished, reset the state. */
148 hv_poll_channel(vss_transaction.recv_channel,
152 /* This is a spurious call! */
153 pr_warn("VSS: Transaction not active\n");
160 static void vss_send_op(struct work_struct *dummy)
162 int op = vss_transaction.msg->vss_hdr.operation;
164 struct hv_vss_msg *vss_msg;
166 /* The transaction state is wrong. */
167 if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED)
170 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
174 vss_msg->vss_hdr.operation = op;
176 vss_transaction.state = HVUTIL_USERSPACE_REQ;
177 rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
179 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
180 if (cancel_delayed_work_sync(&vss_timeout_work)) {
181 vss_respond_to_host(HV_E_FAIL);
182 vss_transaction.state = HVUTIL_READY;
192 * Send a response back to the host.
196 vss_respond_to_host(int error)
198 struct icmsg_hdr *icmsghdrp;
200 struct vmbus_channel *channel;
204 * Copy the global state for completing the transaction. Note that
205 * only one transaction can be active at a time.
208 buf_len = vss_transaction.recv_len;
209 channel = vss_transaction.recv_channel;
210 req_id = vss_transaction.recv_req_id;
212 icmsghdrp = (struct icmsg_hdr *)
213 &recv_buffer[sizeof(struct vmbuspipe_hdr)];
215 if (channel->onchannel_callback == NULL)
217 * We have raced with util driver being unloaded;
222 icmsghdrp->status = error;
224 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
226 vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
227 VM_PKT_DATA_INBAND, 0);
232 * This callback is invoked when we get a VSS message from the host.
233 * The host ensures that only one VSS transaction can be active at a time.
236 void hv_vss_onchannelcallback(void *context)
238 struct vmbus_channel *channel = context;
241 struct hv_vss_msg *vss_msg;
244 struct icmsg_hdr *icmsghdrp;
245 struct icmsg_negotiate *negop = NULL;
247 if (vss_transaction.state > HVUTIL_READY)
250 vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
254 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
255 sizeof(struct vmbuspipe_hdr)];
257 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
258 vmbus_prep_negotiate_resp(icmsghdrp, negop,
259 recv_buffer, UTIL_FW_VERSION,
262 vss_msg = (struct hv_vss_msg *)&recv_buffer[
263 sizeof(struct vmbuspipe_hdr) +
264 sizeof(struct icmsg_hdr)];
267 * Stash away this global state for completing the
268 * transaction; note transactions are serialized.
271 vss_transaction.recv_len = recvlen;
272 vss_transaction.recv_req_id = requestid;
273 vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
275 switch (vss_msg->vss_hdr.operation) {
277 * Initiate a "freeze/thaw"
278 * operation in the guest.
279 * We respond to the host once
280 * the operation is complete.
282 * We send the message to the
283 * user space daemon and the
284 * operation is performed in
289 if (vss_transaction.state < HVUTIL_READY) {
290 /* Userspace is not registered yet */
291 vss_respond_to_host(HV_E_FAIL);
294 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
295 schedule_work(&vss_send_op_work);
296 schedule_delayed_work(&vss_timeout_work,
297 VSS_USERSPACE_TIMEOUT);
300 case VSS_OP_HOT_BACKUP:
301 vss_msg->vss_cf.flags =
302 VSS_HBU_NO_AUTO_RECOVERY;
303 vss_respond_to_host(0);
306 case VSS_OP_GET_DM_INFO:
307 vss_msg->dm_info.flags = 0;
308 vss_respond_to_host(0);
312 vss_respond_to_host(0);
319 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
320 | ICMSGHDRFLAG_RESPONSE;
322 vmbus_sendpacket(channel, recv_buffer,
324 VM_PKT_DATA_INBAND, 0);
329 static void vss_on_reset(void)
331 if (cancel_delayed_work_sync(&vss_timeout_work))
332 vss_respond_to_host(HV_E_FAIL);
333 vss_transaction.state = HVUTIL_DEVICE_INIT;
337 hv_vss_init(struct hv_util_service *srv)
339 if (vmbus_proto_version < VERSION_WIN8_1) {
340 pr_warn("Integration service 'Backup (volume snapshot)'"
341 " not supported on this host version.\n");
344 recv_buffer = srv->recv_buffer;
345 vss_transaction.recv_channel = srv->channel;
348 * When this driver loads, the user level daemon that
349 * processes the host requests may not yet be running.
350 * Defer processing channel callbacks until the daemon
353 vss_transaction.state = HVUTIL_DEVICE_INIT;
355 hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
356 vss_on_msg, vss_on_reset);
363 void hv_vss_deinit(void)
365 vss_transaction.state = HVUTIL_DEVICE_DYING;
366 cancel_delayed_work_sync(&vss_timeout_work);
367 cancel_work_sync(&vss_send_op_work);
368 hvutil_transport_destroy(hvt);