2 * Kernel/userspace transport abstraction for Hyper-V util driver.
4 * Copyright (C) 2015, Vitaly Kuznetsov <vkuznets@redhat.com>
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.
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
18 #include <linux/slab.h>
20 #include <linux/poll.h>
22 #include "hyperv_vmbus.h"
23 #include "hv_utils_transport.h"
25 static DEFINE_SPINLOCK(hvt_list_lock);
26 static struct list_head hvt_list = LIST_HEAD_INIT(hvt_list);
28 static void hvt_reset(struct hvutil_transport *hvt)
37 static ssize_t hvt_op_read(struct file *file, char __user *buf,
38 size_t count, loff_t *ppos)
40 struct hvutil_transport *hvt;
43 hvt = container_of(file->f_op, struct hvutil_transport, fops);
45 if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0 ||
46 hvt->mode != HVUTIL_TRANSPORT_CHARDEV))
49 mutex_lock(&hvt->lock);
51 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
61 if (count < hvt->outmsg_len) {
66 if (!copy_to_user(buf, hvt->outmsg, hvt->outmsg_len))
67 ret = hvt->outmsg_len;
80 mutex_unlock(&hvt->lock);
84 static ssize_t hvt_op_write(struct file *file, const char __user *buf,
85 size_t count, loff_t *ppos)
87 struct hvutil_transport *hvt;
91 hvt = container_of(file->f_op, struct hvutil_transport, fops);
93 inmsg = memdup_user(buf, count);
95 return PTR_ERR(inmsg);
97 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
100 ret = hvt->on_msg(inmsg, count);
104 return ret ? ret : count;
107 static unsigned int hvt_op_poll(struct file *file, poll_table *wait)
109 struct hvutil_transport *hvt;
111 hvt = container_of(file->f_op, struct hvutil_transport, fops);
113 poll_wait(file, &hvt->outmsg_q, wait);
115 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
116 return POLLERR | POLLHUP;
118 if (hvt->outmsg_len > 0)
119 return POLLIN | POLLRDNORM;
124 static int hvt_op_open(struct inode *inode, struct file *file)
126 struct hvutil_transport *hvt;
128 bool issue_reset = false;
130 hvt = container_of(file->f_op, struct hvutil_transport, fops);
132 mutex_lock(&hvt->lock);
134 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
136 } else if (hvt->mode == HVUTIL_TRANSPORT_INIT) {
138 * Switching to CHARDEV mode. We switch bach to INIT when
139 * device gets released.
141 hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
143 else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
145 * We're switching from netlink communication to using char
146 * device. Issue the reset first.
149 hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
157 mutex_unlock(&hvt->lock);
162 static void hvt_transport_free(struct hvutil_transport *hvt)
164 misc_deregister(&hvt->mdev);
169 static int hvt_op_release(struct inode *inode, struct file *file)
171 struct hvutil_transport *hvt;
174 hvt = container_of(file->f_op, struct hvutil_transport, fops);
176 mutex_lock(&hvt->lock);
177 mode_old = hvt->mode;
178 if (hvt->mode != HVUTIL_TRANSPORT_DESTROY)
179 hvt->mode = HVUTIL_TRANSPORT_INIT;
181 * Cleanup message buffers to avoid spurious messages when the daemon
185 mutex_unlock(&hvt->lock);
187 if (mode_old == HVUTIL_TRANSPORT_DESTROY)
188 hvt_transport_free(hvt);
193 static void hvt_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
195 struct hvutil_transport *hvt, *hvt_found = NULL;
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) {
205 spin_unlock(&hvt_list_lock);
207 pr_warn("hvt_cn_callback: spurious message received!\n");
212 * Switching to NETLINK mode. Switching to CHARDEV happens when someone
215 mutex_lock(&hvt->lock);
216 if (hvt->mode == HVUTIL_TRANSPORT_INIT)
217 hvt->mode = HVUTIL_TRANSPORT_NETLINK;
219 if (hvt->mode == HVUTIL_TRANSPORT_NETLINK)
220 hvt_found->on_msg(msg->data, msg->len);
222 pr_warn("hvt_cn_callback: unexpected netlink message!\n");
223 mutex_unlock(&hvt->lock);
226 int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len,
227 void (*on_read_cb)(void))
229 struct cn_msg *cn_msg;
232 if (hvt->mode == HVUTIL_TRANSPORT_INIT ||
233 hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
235 } else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
236 cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC);
239 cn_msg->id.idx = hvt->cn_id.idx;
240 cn_msg->id.val = hvt->cn_id.val;
242 memcpy(cn_msg->data, msg, len);
243 ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC);
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.
254 /* HVUTIL_TRANSPORT_CHARDEV */
255 mutex_lock(&hvt->lock);
256 if (hvt->mode != HVUTIL_TRANSPORT_CHARDEV) {
262 /* Previous message wasn't received */
266 hvt->outmsg = kzalloc(len, GFP_KERNEL);
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);
275 mutex_unlock(&hvt->lock);
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))
284 struct hvutil_transport *hvt;
286 hvt = kzalloc(sizeof(*hvt), GFP_KERNEL);
290 hvt->cn_id.idx = cn_idx;
291 hvt->cn_id.val = cn_val;
293 hvt->mdev.minor = MISC_DYNAMIC_MINOR;
294 hvt->mdev.name = name;
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;
303 hvt->mdev.fops = &hvt->fops;
305 init_waitqueue_head(&hvt->outmsg_q);
306 mutex_init(&hvt->lock);
308 spin_lock(&hvt_list_lock);
309 list_add(&hvt->list, &hvt_list);
310 spin_unlock(&hvt_list_lock);
312 hvt->on_msg = on_msg;
313 hvt->on_reset = on_reset;
315 if (misc_register(&hvt->mdev))
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))
326 spin_lock(&hvt_list_lock);
327 list_del(&hvt->list);
328 spin_unlock(&hvt_list_lock);
333 void hvutil_transport_destroy(struct hvutil_transport *hvt)
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);
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
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);
354 if (mode_old != HVUTIL_TRANSPORT_CHARDEV)
355 hvt_transport_free(hvt);