Jeremy Fitzhardinge | 4bac07c | 2007-07-17 18:37:06 -0700 | [diff] [blame] | 1 | /****************************************************************************** |
| 2 | * xenbus_comms.c |
| 3 | * |
| 4 | * Low level code to talks to Xen Store: ringbuffer and event channel. |
| 5 | * |
| 6 | * Copyright (C) 2005 Rusty Russell, IBM Corporation |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU General Public License version 2 |
| 10 | * as published by the Free Software Foundation; or, when distributed |
| 11 | * separately from the Linux kernel or incorporated into other |
| 12 | * software packages, subject to the following license: |
| 13 | * |
| 14 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
| 15 | * of this source file (the "Software"), to deal in the Software without |
| 16 | * restriction, including without limitation the rights to use, copy, modify, |
| 17 | * merge, publish, distribute, sublicense, and/or sell copies of the Software, |
| 18 | * and to permit persons to whom the Software is furnished to do so, subject to |
| 19 | * the following conditions: |
| 20 | * |
| 21 | * The above copyright notice and this permission notice shall be included in |
| 22 | * all copies or substantial portions of the Software. |
| 23 | * |
| 24 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 25 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 26 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| 27 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 28 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| 29 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
| 30 | * IN THE SOFTWARE. |
| 31 | */ |
| 32 | |
Joe Perches | 283c097 | 2013-06-28 03:21:41 -0700 | [diff] [blame^] | 33 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 34 | |
Jeremy Fitzhardinge | 4bac07c | 2007-07-17 18:37:06 -0700 | [diff] [blame] | 35 | #include <linux/wait.h> |
| 36 | #include <linux/interrupt.h> |
| 37 | #include <linux/sched.h> |
| 38 | #include <linux/err.h> |
| 39 | #include <xen/xenbus.h> |
| 40 | #include <asm/xen/hypervisor.h> |
| 41 | #include <xen/events.h> |
| 42 | #include <xen/page.h> |
| 43 | #include "xenbus_comms.h" |
| 44 | |
| 45 | static int xenbus_irq; |
| 46 | |
| 47 | static DECLARE_WORK(probe_work, xenbus_probe); |
| 48 | |
| 49 | static DECLARE_WAIT_QUEUE_HEAD(xb_waitq); |
| 50 | |
| 51 | static irqreturn_t wake_waiting(int irq, void *unused) |
| 52 | { |
| 53 | if (unlikely(xenstored_ready == 0)) { |
| 54 | xenstored_ready = 1; |
| 55 | schedule_work(&probe_work); |
| 56 | } |
| 57 | |
| 58 | wake_up(&xb_waitq); |
| 59 | return IRQ_HANDLED; |
| 60 | } |
| 61 | |
| 62 | static int check_indexes(XENSTORE_RING_IDX cons, XENSTORE_RING_IDX prod) |
| 63 | { |
| 64 | return ((prod - cons) <= XENSTORE_RING_SIZE); |
| 65 | } |
| 66 | |
| 67 | static void *get_output_chunk(XENSTORE_RING_IDX cons, |
| 68 | XENSTORE_RING_IDX prod, |
| 69 | char *buf, uint32_t *len) |
| 70 | { |
| 71 | *len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod); |
| 72 | if ((XENSTORE_RING_SIZE - (prod - cons)) < *len) |
| 73 | *len = XENSTORE_RING_SIZE - (prod - cons); |
| 74 | return buf + MASK_XENSTORE_IDX(prod); |
| 75 | } |
| 76 | |
| 77 | static const void *get_input_chunk(XENSTORE_RING_IDX cons, |
| 78 | XENSTORE_RING_IDX prod, |
| 79 | const char *buf, uint32_t *len) |
| 80 | { |
| 81 | *len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(cons); |
| 82 | if ((prod - cons) < *len) |
| 83 | *len = prod - cons; |
| 84 | return buf + MASK_XENSTORE_IDX(cons); |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * xb_write - low level write |
| 89 | * @data: buffer to send |
| 90 | * @len: length of buffer |
| 91 | * |
| 92 | * Returns 0 on success, error otherwise. |
| 93 | */ |
| 94 | int xb_write(const void *data, unsigned len) |
| 95 | { |
| 96 | struct xenstore_domain_interface *intf = xen_store_interface; |
| 97 | XENSTORE_RING_IDX cons, prod; |
| 98 | int rc; |
| 99 | |
| 100 | while (len != 0) { |
| 101 | void *dst; |
| 102 | unsigned int avail; |
| 103 | |
| 104 | rc = wait_event_interruptible( |
| 105 | xb_waitq, |
| 106 | (intf->req_prod - intf->req_cons) != |
| 107 | XENSTORE_RING_SIZE); |
| 108 | if (rc < 0) |
| 109 | return rc; |
| 110 | |
| 111 | /* Read indexes, then verify. */ |
| 112 | cons = intf->req_cons; |
| 113 | prod = intf->req_prod; |
| 114 | if (!check_indexes(cons, prod)) { |
| 115 | intf->req_cons = intf->req_prod = 0; |
| 116 | return -EIO; |
| 117 | } |
| 118 | |
| 119 | dst = get_output_chunk(cons, prod, intf->req, &avail); |
| 120 | if (avail == 0) |
| 121 | continue; |
| 122 | if (avail > len) |
| 123 | avail = len; |
| 124 | |
| 125 | /* Must write data /after/ reading the consumer index. */ |
| 126 | mb(); |
| 127 | |
| 128 | memcpy(dst, data, avail); |
| 129 | data += avail; |
| 130 | len -= avail; |
| 131 | |
| 132 | /* Other side must not see new producer until data is there. */ |
| 133 | wmb(); |
| 134 | intf->req_prod += avail; |
| 135 | |
| 136 | /* Implies mb(): other side will see the updated producer. */ |
| 137 | notify_remote_via_evtchn(xen_store_evtchn); |
| 138 | } |
| 139 | |
| 140 | return 0; |
| 141 | } |
| 142 | |
| 143 | int xb_data_to_read(void) |
| 144 | { |
| 145 | struct xenstore_domain_interface *intf = xen_store_interface; |
| 146 | return (intf->rsp_cons != intf->rsp_prod); |
| 147 | } |
| 148 | |
| 149 | int xb_wait_for_data_to_read(void) |
| 150 | { |
| 151 | return wait_event_interruptible(xb_waitq, xb_data_to_read()); |
| 152 | } |
| 153 | |
| 154 | int xb_read(void *data, unsigned len) |
| 155 | { |
| 156 | struct xenstore_domain_interface *intf = xen_store_interface; |
| 157 | XENSTORE_RING_IDX cons, prod; |
| 158 | int rc; |
| 159 | |
| 160 | while (len != 0) { |
| 161 | unsigned int avail; |
| 162 | const char *src; |
| 163 | |
| 164 | rc = xb_wait_for_data_to_read(); |
| 165 | if (rc < 0) |
| 166 | return rc; |
| 167 | |
| 168 | /* Read indexes, then verify. */ |
| 169 | cons = intf->rsp_cons; |
| 170 | prod = intf->rsp_prod; |
| 171 | if (!check_indexes(cons, prod)) { |
| 172 | intf->rsp_cons = intf->rsp_prod = 0; |
| 173 | return -EIO; |
| 174 | } |
| 175 | |
| 176 | src = get_input_chunk(cons, prod, intf->rsp, &avail); |
| 177 | if (avail == 0) |
| 178 | continue; |
| 179 | if (avail > len) |
| 180 | avail = len; |
| 181 | |
| 182 | /* Must read data /after/ reading the producer index. */ |
| 183 | rmb(); |
| 184 | |
| 185 | memcpy(data, src, avail); |
| 186 | data += avail; |
| 187 | len -= avail; |
| 188 | |
| 189 | /* Other side must not see free space until we've copied out */ |
| 190 | mb(); |
| 191 | intf->rsp_cons += avail; |
| 192 | |
| 193 | pr_debug("Finished read of %i bytes (%i to go)\n", avail, len); |
| 194 | |
| 195 | /* Implies mb(): other side will see the updated consumer. */ |
| 196 | notify_remote_via_evtchn(xen_store_evtchn); |
| 197 | } |
| 198 | |
| 199 | return 0; |
| 200 | } |
| 201 | |
| 202 | /** |
| 203 | * xb_init_comms - Set up interrupt handler off store event channel. |
| 204 | */ |
| 205 | int xb_init_comms(void) |
| 206 | { |
| 207 | struct xenstore_domain_interface *intf = xen_store_interface; |
Jeremy Fitzhardinge | 4bac07c | 2007-07-17 18:37:06 -0700 | [diff] [blame] | 208 | |
| 209 | if (intf->req_prod != intf->req_cons) |
Joe Perches | 283c097 | 2013-06-28 03:21:41 -0700 | [diff] [blame^] | 210 | pr_err("request ring is not quiescent (%08x:%08x)!\n", |
| 211 | intf->req_cons, intf->req_prod); |
Jeremy Fitzhardinge | 4bac07c | 2007-07-17 18:37:06 -0700 | [diff] [blame] | 212 | |
| 213 | if (intf->rsp_prod != intf->rsp_cons) { |
Joe Perches | 283c097 | 2013-06-28 03:21:41 -0700 | [diff] [blame^] | 214 | pr_warn("response ring is not quiescent (%08x:%08x): fixing up\n", |
| 215 | intf->rsp_cons, intf->rsp_prod); |
Olaf Hering | 116df6f | 2011-08-25 18:34:45 +0200 | [diff] [blame] | 216 | /* breaks kdump */ |
| 217 | if (!reset_devices) |
| 218 | intf->rsp_cons = intf->rsp_prod; |
Jeremy Fitzhardinge | 4bac07c | 2007-07-17 18:37:06 -0700 | [diff] [blame] | 219 | } |
| 220 | |
Jeremy Fitzhardinge | 7d88d32 | 2008-05-26 23:31:26 +0100 | [diff] [blame] | 221 | if (xenbus_irq) { |
| 222 | /* Already have an irq; assume we're resuming */ |
| 223 | rebind_evtchn_irq(xen_store_evtchn, xenbus_irq); |
| 224 | } else { |
| 225 | int err; |
| 226 | err = bind_evtchn_to_irqhandler(xen_store_evtchn, wake_waiting, |
| 227 | 0, "xenbus", &xb_waitq); |
Stefano Stabellini | ecc635f | 2012-09-14 12:13:12 +0100 | [diff] [blame] | 228 | if (err < 0) { |
Joe Perches | 283c097 | 2013-06-28 03:21:41 -0700 | [diff] [blame^] | 229 | pr_err("request irq failed %i\n", err); |
Jeremy Fitzhardinge | 7d88d32 | 2008-05-26 23:31:26 +0100 | [diff] [blame] | 230 | return err; |
| 231 | } |
Jeremy Fitzhardinge | 4bac07c | 2007-07-17 18:37:06 -0700 | [diff] [blame] | 232 | |
Jeremy Fitzhardinge | 7d88d32 | 2008-05-26 23:31:26 +0100 | [diff] [blame] | 233 | xenbus_irq = err; |
Jeremy Fitzhardinge | 4bac07c | 2007-07-17 18:37:06 -0700 | [diff] [blame] | 234 | } |
| 235 | |
Jeremy Fitzhardinge | 4bac07c | 2007-07-17 18:37:06 -0700 | [diff] [blame] | 236 | return 0; |
| 237 | } |
Daniel De Graaf | d2fb4c5 | 2012-05-08 09:46:57 -0400 | [diff] [blame] | 238 | |
| 239 | void xb_deinit_comms(void) |
| 240 | { |
| 241 | unbind_from_irqhandler(xenbus_irq, &xb_waitq); |
| 242 | xenbus_irq = 0; |
| 243 | } |