| 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 | |