1 /* 2 * Kernel/userspace transport abstraction for Hyper-V util driver. 3 * 4 * Copyright (C) 2015, Vitaly Kuznetsov <vkuznets@redhat.com> 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 as published 8 * by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, but 11 * WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or 13 * NON INFRINGEMENT. See the GNU General Public License for more 14 * details. 15 * 16 */ 17 18 #include <linux/slab.h> 19 #include <linux/fs.h> 20 #include <linux/poll.h> 21 22 #include "hyperv_vmbus.h" 23 #include "hv_utils_transport.h" 24 25 static DEFINE_SPINLOCK(hvt_list_lock); 26 static struct list_head hvt_list = LIST_HEAD_INIT(hvt_list); 27 28 static void hvt_reset(struct hvutil_transport *hvt) 29 { 30 kfree(hvt->outmsg); 31 hvt->outmsg = NULL; 32 hvt->outmsg_len = 0; 33 if (hvt->on_reset) 34 hvt->on_reset(); 35 } 36 37 static ssize_t hvt_op_read(struct file *file, char __user *buf, 38 size_t count, loff_t *ppos) 39 { 40 struct hvutil_transport *hvt; 41 int ret; 42 43 hvt = container_of(file->f_op, struct hvutil_transport, fops); 44 45 if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0 || 46 hvt->mode != HVUTIL_TRANSPORT_CHARDEV)) 47 return -EINTR; 48 49 mutex_lock(&hvt->lock); 50 51 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) { 52 ret = -EBADF; 53 goto out_unlock; 54 } 55 56 if (!hvt->outmsg) { 57 ret = -EAGAIN; 58 goto out_unlock; 59 } 60 61 if (count < hvt->outmsg_len) { 62 ret = -EINVAL; 63 goto out_unlock; 64 } 65 66 if (!copy_to_user(buf, hvt->outmsg, hvt->outmsg_len)) 67 ret = hvt->outmsg_len; 68 else 69 ret = -EFAULT; 70 71 kfree(hvt->outmsg); 72 hvt->outmsg = NULL; 73 hvt->outmsg_len = 0; 74 75 if (hvt->on_read) 76 hvt->on_read(); 77 hvt->on_read = NULL; 78 79 out_unlock: 80 mutex_unlock(&hvt->lock); 81 return ret; 82 } 83 84 static ssize_t hvt_op_write(struct file *file, const char __user *buf, 85 size_t count, loff_t *ppos) 86 { 87 struct hvutil_transport *hvt; 88 u8 *inmsg; 89 int ret; 90 91 hvt = container_of(file->f_op, struct hvutil_transport, fops); 92 93 inmsg = memdup_user(buf, count); 94 if (IS_ERR(inmsg)) 95 return PTR_ERR(inmsg); 96 97 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) 98 ret = -EBADF; 99 else 100 ret = hvt->on_msg(inmsg, count); 101 102 kfree(inmsg); 103 104 return ret ? ret : count; 105 } 106 107 static unsigned int hvt_op_poll(struct file *file, poll_table *wait) 108 { 109 struct hvutil_transport *hvt; 110 111 hvt = container_of(file->f_op, struct hvutil_transport, fops); 112 113 poll_wait(file, &hvt->outmsg_q, wait); 114 115 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) 116 return POLLERR | POLLHUP; 117 118 if (hvt->outmsg_len > 0) 119 return POLLIN | POLLRDNORM; 120 121 return 0; 122 } 123 124 static int hvt_op_open(struct inode *inode, struct file *file) 125 { 126 struct hvutil_transport *hvt; 127 int ret = 0; 128 bool issue_reset = false; 129 130 hvt = container_of(file->f_op, struct hvutil_transport, fops); 131 132 mutex_lock(&hvt->lock); 133 134 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) { 135 ret = -EBADF; 136 } else if (hvt->mode == HVUTIL_TRANSPORT_INIT) { 137 /* 138 * Switching to CHARDEV mode. We switch bach to INIT when 139 * device gets released. 140 */ 141 hvt->mode = HVUTIL_TRANSPORT_CHARDEV; 142 } 143 else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) { 144 /* 145 * We're switching from netlink communication to using char 146 * device. Issue the reset first. 147 */ 148 issue_reset = true; 149 hvt->mode = HVUTIL_TRANSPORT_CHARDEV; 150 } else { 151 ret = -EBUSY; 152 } 153 154 if (issue_reset) 155 hvt_reset(hvt); 156 157 mutex_unlock(&hvt->lock); 158 159 return ret; 160 } 161 162 static void hvt_transport_free(struct hvutil_transport *hvt) 163 { 164 misc_deregister(&hvt->mdev); 165 kfree(hvt->outmsg); 166 kfree(hvt); 167 } 168 169 static int hvt_op_release(struct inode *inode, struct file *file) 170 { 171 struct hvutil_transport *hvt; 172 int mode_old; 173 174 hvt = container_of(file->f_op, struct hvutil_transport, fops); 175 176 mutex_lock(&hvt->lock); 177 mode_old = hvt->mode; 178 if (hvt->mode != HVUTIL_TRANSPORT_DESTROY) 179 hvt->mode = HVUTIL_TRANSPORT_INIT; 180 /* 181 * Cleanup message buffers to avoid spurious messages when the daemon 182 * connects back. 183 */ 184 hvt_reset(hvt); 185 mutex_unlock(&hvt->lock); 186 187 if (mode_old == HVUTIL_TRANSPORT_DESTROY) 188 hvt_transport_free(hvt); 189 190 return 0; 191 } 192 193 static void hvt_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp) 194 { 195 struct hvutil_transport *hvt, *hvt_found = NULL; 196 197 spin_lock(&hvt_list_lock); 198 list_for_each_entry(hvt, &hvt_list, list) { 199 if (hvt->cn_id.idx == msg->id.idx && 200 hvt->cn_id.val == msg->id.val) { 201 hvt_found = hvt; 202 break; 203 } 204 } 205 spin_unlock(&hvt_list_lock); 206 if (!hvt_found) { 207 pr_warn("hvt_cn_callback: spurious message received!\n"); 208 return; 209 } 210 211 /* 212 * Switching to NETLINK mode. Switching to CHARDEV happens when someone 213 * opens the device. 214 */ 215 mutex_lock(&hvt->lock); 216 if (hvt->mode == HVUTIL_TRANSPORT_INIT) 217 hvt->mode = HVUTIL_TRANSPORT_NETLINK; 218 219 if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) 220 hvt_found->on_msg(msg->data, msg->len); 221 else 222 pr_warn("hvt_cn_callback: unexpected netlink message!\n"); 223 mutex_unlock(&hvt->lock); 224 } 225 226 int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len, 227 void (*on_read_cb)(void)) 228 { 229 struct cn_msg *cn_msg; 230 int ret = 0; 231 232 if (hvt->mode == HVUTIL_TRANSPORT_INIT || 233 hvt->mode == HVUTIL_TRANSPORT_DESTROY) { 234 return -EINVAL; 235 } else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) { 236 cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC); 237 if (!cn_msg) 238 return -ENOMEM; 239 cn_msg->id.idx = hvt->cn_id.idx; 240 cn_msg->id.val = hvt->cn_id.val; 241 cn_msg->len = len; 242 memcpy(cn_msg->data, msg, len); 243 ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC); 244 kfree(cn_msg); 245 /* 246 * We don't know when netlink messages are delivered but unlike 247 * in CHARDEV mode we're not blocked and we can send next 248 * messages right away. 249 */ 250 if (on_read_cb) 251 on_read_cb(); 252 return ret; 253 } 254 /* HVUTIL_TRANSPORT_CHARDEV */ 255 mutex_lock(&hvt->lock); 256 if (hvt->mode != HVUTIL_TRANSPORT_CHARDEV) { 257 ret = -EINVAL; 258 goto out_unlock; 259 } 260 261 if (hvt->outmsg) { 262 /* Previous message wasn't received */ 263 ret = -EFAULT; 264 goto out_unlock; 265 } 266 hvt->outmsg = kzalloc(len, GFP_KERNEL); 267 if (hvt->outmsg) { 268 memcpy(hvt->outmsg, msg, len); 269 hvt->outmsg_len = len; 270 hvt->on_read = on_read_cb; 271 wake_up_interruptible(&hvt->outmsg_q); 272 } else 273 ret = -ENOMEM; 274 out_unlock: 275 mutex_unlock(&hvt->lock); 276 return ret; 277 } 278 279 struct hvutil_transport *hvutil_transport_init(const char *name, 280 u32 cn_idx, u32 cn_val, 281 int (*on_msg)(void *, int), 282 void (*on_reset)(void)) 283 { 284 struct hvutil_transport *hvt; 285 286 hvt = kzalloc(sizeof(*hvt), GFP_KERNEL); 287 if (!hvt) 288 return NULL; 289 290 hvt->cn_id.idx = cn_idx; 291 hvt->cn_id.val = cn_val; 292 293 hvt->mdev.minor = MISC_DYNAMIC_MINOR; 294 hvt->mdev.name = name; 295 296 hvt->fops.owner = THIS_MODULE; 297 hvt->fops.read = hvt_op_read; 298 hvt->fops.write = hvt_op_write; 299 hvt->fops.poll = hvt_op_poll; 300 hvt->fops.open = hvt_op_open; 301 hvt->fops.release = hvt_op_release; 302 303 hvt->mdev.fops = &hvt->fops; 304 305 init_waitqueue_head(&hvt->outmsg_q); 306 mutex_init(&hvt->lock); 307 308 spin_lock(&hvt_list_lock); 309 list_add(&hvt->list, &hvt_list); 310 spin_unlock(&hvt_list_lock); 311 312 hvt->on_msg = on_msg; 313 hvt->on_reset = on_reset; 314 315 if (misc_register(&hvt->mdev)) 316 goto err_free_hvt; 317 318 /* Use cn_id.idx/cn_id.val to determine if we need to setup netlink */ 319 if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0 && 320 cn_add_callback(&hvt->cn_id, name, hvt_cn_callback)) 321 goto err_free_hvt; 322 323 return hvt; 324 325 err_free_hvt: 326 spin_lock(&hvt_list_lock); 327 list_del(&hvt->list); 328 spin_unlock(&hvt_list_lock); 329 kfree(hvt); 330 return NULL; 331 } 332 333 void hvutil_transport_destroy(struct hvutil_transport *hvt) 334 { 335 int mode_old; 336 337 mutex_lock(&hvt->lock); 338 mode_old = hvt->mode; 339 hvt->mode = HVUTIL_TRANSPORT_DESTROY; 340 wake_up_interruptible(&hvt->outmsg_q); 341 mutex_unlock(&hvt->lock); 342 343 /* 344 * In case we were in 'chardev' mode we still have an open fd so we 345 * have to defer freeing the device. Netlink interface can be freed 346 * now. 347 */ 348 spin_lock(&hvt_list_lock); 349 list_del(&hvt->list); 350 spin_unlock(&hvt_list_lock); 351 if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0) 352 cn_del_callback(&hvt->cn_id); 353 354 if (mode_old != HVUTIL_TRANSPORT_CHARDEV) 355 hvt_transport_free(hvt); 356 } 357