1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
/******************************************************************************
* xenbus_comms.c
*
* Low level code to talks to Xen Store: ringbuffer and event channel.
*
* Copyright (C) 2005 Rusty Russell, IBM Corporation
*
* This file may be distributed separately from the Linux kernel, or
* incorporated into other software packages, subject to the following license:
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this source file (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy, modify,
* merge, publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <types.h>
#include <wait.h>
#include <mm.h>
#include <hypervisor.h>
#include <events.h>
#include <os.h>
#include <lib.h>
#include <xenbus.h>
#include "xenbus_comms.h"
static int xenbus_irq;
extern void xenbus_probe(void *);
extern int xenstored_ready;
DECLARE_WAIT_QUEUE_HEAD(xb_waitq);
static inline struct xenstore_domain_interface *xenstore_domain_interface(void)
{
return mfn_to_virt(start_info.store_mfn);
}
static void wake_waiting(int port, struct pt_regs *regs)
{
wake_up(&xb_waitq);
}
static int check_indexes(XENSTORE_RING_IDX cons, XENSTORE_RING_IDX prod)
{
return ((prod - cons) <= XENSTORE_RING_SIZE);
}
static void *get_output_chunk(XENSTORE_RING_IDX cons,
XENSTORE_RING_IDX prod,
char *buf, uint32_t *len)
{
*len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod);
if ((XENSTORE_RING_SIZE - (prod - cons)) < *len)
*len = XENSTORE_RING_SIZE - (prod - cons);
return buf + MASK_XENSTORE_IDX(prod);
}
static const void *get_input_chunk(XENSTORE_RING_IDX cons,
XENSTORE_RING_IDX prod,
const char *buf, uint32_t *len)
{
*len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(cons);
if ((prod - cons) < *len)
*len = prod - cons;
return buf + MASK_XENSTORE_IDX(cons);
}
int xb_write(const void *data, unsigned len)
{
struct xenstore_domain_interface *intf = xenstore_domain_interface();
XENSTORE_RING_IDX cons, prod;
while (len != 0) {
void *dst;
unsigned int avail;
wait_event(xb_waitq, (intf->req_prod - intf->req_cons) !=
XENSTORE_RING_SIZE);
/* Read indexes, then verify. */
cons = intf->req_cons;
prod = intf->req_prod;
mb();
if (!check_indexes(cons, prod))
return -EIO;
dst = get_output_chunk(cons, prod, intf->req, &avail);
if (avail == 0)
continue;
if (avail > len)
avail = len;
memcpy(dst, data, avail);
data = (void*) ( (unsigned long)data + avail );
len -= avail;
/* Other side must not see new header until data is there. */
wmb();
intf->req_prod += avail;
/* This implies mb() before other side sees interrupt. */
notify_remote_via_evtchn(start_info.store_evtchn);
}
return 0;
}
int xb_read(void *data, unsigned len)
{
struct xenstore_domain_interface *intf = xenstore_domain_interface();
XENSTORE_RING_IDX cons, prod;
while (len != 0) {
unsigned int avail;
const char *src;
wait_event(xb_waitq,
intf->rsp_cons != intf->rsp_prod);
/* Read indexes, then verify. */
cons = intf->rsp_cons;
prod = intf->rsp_prod;
mb();
if (!check_indexes(cons, prod))
return -EIO;
src = get_input_chunk(cons, prod, intf->rsp, &avail);
if (avail == 0)
continue;
if (avail > len)
avail = len;
/* We must read header before we read data. */
rmb();
memcpy(data, src, avail);
data = (void*) ( (unsigned long)data + avail );
len -= avail;
/* Other side must not see free space until we've copied out */
mb();
intf->rsp_cons += avail;
printk("Finished read of %i bytes (%i to go)\n", avail, len);
/* Implies mb(): they will see new header. */
notify_remote_via_evtchn(start_info.store_evtchn);
}
return 0;
}
/* Set up interrupt handler off store event channel. */
int xb_init_comms(void)
{
int err;
if (xenbus_irq)
unbind_evtchn(xenbus_irq);
err = bind_evtchn(
start_info.store_evtchn, wake_waiting);
if (err <= 0) {
printk("XENBUS request irq failed %i\n", err);
return err;
}
xenbus_irq = err;
return 0;
}
|
