1 | /* $NetBSD: xenbus_comms.c,v 1.15 2016/07/07 06:55:40 msaitoh Exp $ */ |
2 | /****************************************************************************** |
3 | * xenbus_comms.c |
4 | * |
5 | * Low level code to talks to Xen Store: ringbuffer and event channel. |
6 | * |
7 | * Copyright (C) 2005 Rusty Russell, IBM Corporation |
8 | * |
9 | * This file may be distributed separately from the Linux kernel, or |
10 | * incorporated into other software packages, subject to the following license: |
11 | * |
12 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
13 | * of this source file (the "Software"), to deal in the Software without |
14 | * restriction, including without limitation the rights to use, copy, modify, |
15 | * merge, publish, distribute, sublicense, and/or sell copies of the Software, |
16 | * and to permit persons to whom the Software is furnished to do so, subject to |
17 | * the following conditions: |
18 | * |
19 | * The above copyright notice and this permission notice shall be included in |
20 | * all copies or substantial portions of the Software. |
21 | * |
22 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
23 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
24 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
25 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
26 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
27 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
28 | * IN THE SOFTWARE. |
29 | */ |
30 | |
31 | #include <sys/cdefs.h> |
32 | __KERNEL_RCSID(0, "$NetBSD: xenbus_comms.c,v 1.15 2016/07/07 06:55:40 msaitoh Exp $" ); |
33 | |
34 | #include <sys/types.h> |
35 | #include <sys/null.h> |
36 | #include <sys/errno.h> |
37 | #include <sys/param.h> |
38 | #include <sys/proc.h> |
39 | #include <sys/systm.h> |
40 | |
41 | #include <xen/xen.h> /* for xendomain_is_dom0() */ |
42 | #include <xen/hypervisor.h> |
43 | #include <xen/evtchn.h> |
44 | #include <xen/xenbus.h> |
45 | #include "xenbus_comms.h" |
46 | |
47 | #undef XENDEBUG |
48 | #ifdef XENDEBUG |
49 | #define XENPRINTF(x) printf x |
50 | #else |
51 | #define XENPRINTF(x) |
52 | #endif |
53 | |
54 | struct xenstore_domain_interface *xenstore_interface; |
55 | |
56 | extern int xenstored_ready; |
57 | // static DECLARE_WORK(probe_work, xenbus_probe, NULL); |
58 | |
59 | static int wake_waiting(void *); |
60 | static int check_indexes(XENSTORE_RING_IDX, XENSTORE_RING_IDX); |
61 | static void *get_output_chunk(XENSTORE_RING_IDX, XENSTORE_RING_IDX, |
62 | char *, uint32_t *); |
63 | static const void *get_input_chunk(XENSTORE_RING_IDX, XENSTORE_RING_IDX, |
64 | const char *, uint32_t *); |
65 | |
66 | |
67 | static inline struct xenstore_domain_interface * |
68 | xenstore_domain_interface(void) |
69 | { |
70 | return xenstore_interface; |
71 | } |
72 | |
73 | static int |
74 | wake_waiting(void *arg) |
75 | { |
76 | if (__predict_false(xenstored_ready == 0 && xendomain_is_dom0())) { |
77 | xenstored_ready = 1; |
78 | wakeup(&xenstored_ready); |
79 | } |
80 | |
81 | wakeup(&xenstore_interface); |
82 | return 1; |
83 | } |
84 | |
85 | static int |
86 | check_indexes(XENSTORE_RING_IDX cons, XENSTORE_RING_IDX prod) |
87 | { |
88 | return ((prod - cons) <= XENSTORE_RING_SIZE); |
89 | } |
90 | |
91 | static void * |
92 | get_output_chunk(XENSTORE_RING_IDX cons, |
93 | XENSTORE_RING_IDX prod, |
94 | char *buf, uint32_t *len) |
95 | { |
96 | *len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod); |
97 | if ((XENSTORE_RING_SIZE - (prod - cons)) < *len) |
98 | *len = XENSTORE_RING_SIZE - (prod - cons); |
99 | return buf + MASK_XENSTORE_IDX(prod); |
100 | } |
101 | |
102 | static const void * |
103 | get_input_chunk(XENSTORE_RING_IDX cons, |
104 | XENSTORE_RING_IDX prod, |
105 | const char *buf, uint32_t *len) |
106 | { |
107 | *len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(cons); |
108 | if ((prod - cons) < *len) |
109 | *len = prod - cons; |
110 | return buf + MASK_XENSTORE_IDX(cons); |
111 | } |
112 | |
113 | int |
114 | xb_write(const void *data, unsigned len) |
115 | { |
116 | struct xenstore_domain_interface *intf = xenstore_domain_interface(); |
117 | XENSTORE_RING_IDX cons, prod; |
118 | |
119 | int s = spltty(); |
120 | |
121 | while (len != 0) { |
122 | void *dst; |
123 | unsigned int avail; |
124 | |
125 | while ((intf->req_prod - intf->req_cons) == XENSTORE_RING_SIZE) { |
126 | XENPRINTF(("xb_write tsleep\n" )); |
127 | tsleep(&xenstore_interface, PRIBIO, "wrst" , 0); |
128 | XENPRINTF(("xb_write tsleep done\n" )); |
129 | } |
130 | |
131 | /* Read indexes, then verify. */ |
132 | cons = intf->req_cons; |
133 | prod = intf->req_prod; |
134 | xen_rmb(); |
135 | if (!check_indexes(cons, prod)) { |
136 | splx(s); |
137 | return EIO; |
138 | } |
139 | |
140 | dst = get_output_chunk(cons, prod, intf->req, &avail); |
141 | if (avail == 0) |
142 | continue; |
143 | if (avail > len) |
144 | avail = len; |
145 | |
146 | memcpy(dst, data, avail); |
147 | data = (const char *)data + avail; |
148 | len -= avail; |
149 | |
150 | /* Other side must not see new header until data is there. */ |
151 | xen_rmb(); |
152 | intf->req_prod += avail; |
153 | xen_rmb(); |
154 | |
155 | hypervisor_notify_via_evtchn(xen_start_info.store_evtchn); |
156 | } |
157 | |
158 | splx(s); |
159 | return 0; |
160 | } |
161 | |
162 | int |
163 | xb_read(void *data, unsigned len) |
164 | { |
165 | struct xenstore_domain_interface *intf = xenstore_domain_interface(); |
166 | XENSTORE_RING_IDX cons, prod; |
167 | |
168 | int s = spltty(); |
169 | |
170 | while (len != 0) { |
171 | unsigned int avail; |
172 | const char *src; |
173 | |
174 | while (intf->rsp_cons == intf->rsp_prod) |
175 | tsleep(&xenstore_interface, PRIBIO, "rdst" , 0); |
176 | |
177 | /* Read indexes, then verify. */ |
178 | cons = intf->rsp_cons; |
179 | prod = intf->rsp_prod; |
180 | xen_rmb(); |
181 | if (!check_indexes(cons, prod)) { |
182 | XENPRINTF(("xb_read EIO\n" )); |
183 | splx(s); |
184 | return EIO; |
185 | } |
186 | |
187 | src = get_input_chunk(cons, prod, intf->rsp, &avail); |
188 | if (avail == 0) |
189 | continue; |
190 | if (avail > len) |
191 | avail = len; |
192 | |
193 | /* We must read header before we read data. */ |
194 | xen_rmb(); |
195 | |
196 | memcpy(data, src, avail); |
197 | data = (char *)data + avail; |
198 | len -= avail; |
199 | |
200 | /* Other side must not see free space until we've copied out */ |
201 | xen_rmb(); |
202 | intf->rsp_cons += avail; |
203 | xen_rmb(); |
204 | |
205 | XENPRINTF(("Finished read of %i bytes (%i to go)\n" , |
206 | avail, len)); |
207 | |
208 | hypervisor_notify_via_evtchn(xen_start_info.store_evtchn); |
209 | } |
210 | |
211 | splx(s); |
212 | return 0; |
213 | } |
214 | |
215 | /* Set up interrupt handler of store event channel. */ |
216 | int |
217 | xb_init_comms(device_t dev) |
218 | { |
219 | int evtchn; |
220 | |
221 | evtchn = xen_start_info.store_evtchn; |
222 | |
223 | event_set_handler(evtchn, wake_waiting, NULL, IPL_TTY, "xenbus" ); |
224 | hypervisor_enable_event(evtchn); |
225 | aprint_verbose_dev(dev, "using event channel %d\n" , evtchn); |
226 | |
227 | return 0; |
228 | } |
229 | |
230 | void |
231 | xb_suspend_comms(device_t dev) |
232 | { |
233 | int evtchn; |
234 | |
235 | evtchn = xen_start_info.store_evtchn; |
236 | |
237 | hypervisor_mask_event(evtchn); |
238 | event_remove_handler(evtchn, wake_waiting, NULL); |
239 | aprint_verbose_dev(dev, "removed event channel %d\n" , evtchn); |
240 | } |
241 | |
242 | /* |
243 | * Local variables: |
244 | * c-file-style: "linux" |
245 | * indent-tabs-mode: t |
246 | * c-indent-level: 8 |
247 | * c-basic-offset: 8 |
248 | * tab-width: 8 |
249 | * End: |
250 | */ |
251 | |