351 lines
7.6 KiB
C
351 lines
7.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Kernel/userspace transport abstraction for Hyper-V util driver.
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*
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* Copyright (C) 2015, Vitaly Kuznetsov <vkuznets@redhat.com>
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*/
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/poll.h>
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#include "hyperv_vmbus.h"
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#include "hv_utils_transport.h"
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static DEFINE_SPINLOCK(hvt_list_lock);
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static LIST_HEAD(hvt_list);
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static void hvt_reset(struct hvutil_transport *hvt)
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{
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kfree(hvt->outmsg);
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hvt->outmsg = NULL;
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hvt->outmsg_len = 0;
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if (hvt->on_reset)
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hvt->on_reset();
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}
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static ssize_t hvt_op_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct hvutil_transport *hvt;
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int ret;
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hvt = container_of(file->f_op, struct hvutil_transport, fops);
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if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0 ||
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hvt->mode != HVUTIL_TRANSPORT_CHARDEV))
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return -EINTR;
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mutex_lock(&hvt->lock);
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if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
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ret = -EBADF;
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goto out_unlock;
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}
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if (!hvt->outmsg) {
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ret = -EAGAIN;
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goto out_unlock;
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}
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if (count < hvt->outmsg_len) {
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ret = -EINVAL;
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goto out_unlock;
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}
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if (!copy_to_user(buf, hvt->outmsg, hvt->outmsg_len))
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ret = hvt->outmsg_len;
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else
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ret = -EFAULT;
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kfree(hvt->outmsg);
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hvt->outmsg = NULL;
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hvt->outmsg_len = 0;
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if (hvt->on_read)
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hvt->on_read();
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hvt->on_read = NULL;
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out_unlock:
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mutex_unlock(&hvt->lock);
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return ret;
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}
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static ssize_t hvt_op_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct hvutil_transport *hvt;
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u8 *inmsg;
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int ret;
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hvt = container_of(file->f_op, struct hvutil_transport, fops);
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inmsg = memdup_user(buf, count);
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if (IS_ERR(inmsg))
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return PTR_ERR(inmsg);
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if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
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ret = -EBADF;
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else
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ret = hvt->on_msg(inmsg, count);
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kfree(inmsg);
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return ret ? ret : count;
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}
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static __poll_t hvt_op_poll(struct file *file, poll_table *wait)
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{
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struct hvutil_transport *hvt;
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hvt = container_of(file->f_op, struct hvutil_transport, fops);
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poll_wait(file, &hvt->outmsg_q, wait);
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if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
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return EPOLLERR | EPOLLHUP;
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if (hvt->outmsg_len > 0)
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return EPOLLIN | EPOLLRDNORM;
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return 0;
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}
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static int hvt_op_open(struct inode *inode, struct file *file)
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{
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struct hvutil_transport *hvt;
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int ret = 0;
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bool issue_reset = false;
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hvt = container_of(file->f_op, struct hvutil_transport, fops);
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mutex_lock(&hvt->lock);
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if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
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ret = -EBADF;
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} else if (hvt->mode == HVUTIL_TRANSPORT_INIT) {
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/*
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* Switching to CHARDEV mode. We switch bach to INIT when
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* device gets released.
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*/
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hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
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}
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else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
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/*
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* We're switching from netlink communication to using char
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* device. Issue the reset first.
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*/
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issue_reset = true;
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hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
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} else {
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ret = -EBUSY;
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}
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if (issue_reset)
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hvt_reset(hvt);
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mutex_unlock(&hvt->lock);
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return ret;
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}
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static void hvt_transport_free(struct hvutil_transport *hvt)
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{
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misc_deregister(&hvt->mdev);
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kfree(hvt->outmsg);
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kfree(hvt);
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}
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static int hvt_op_release(struct inode *inode, struct file *file)
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{
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struct hvutil_transport *hvt;
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int mode_old;
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hvt = container_of(file->f_op, struct hvutil_transport, fops);
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mutex_lock(&hvt->lock);
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mode_old = hvt->mode;
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if (hvt->mode != HVUTIL_TRANSPORT_DESTROY)
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hvt->mode = HVUTIL_TRANSPORT_INIT;
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/*
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* Cleanup message buffers to avoid spurious messages when the daemon
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* connects back.
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*/
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hvt_reset(hvt);
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if (mode_old == HVUTIL_TRANSPORT_DESTROY)
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complete(&hvt->release);
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mutex_unlock(&hvt->lock);
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return 0;
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}
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static void hvt_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
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{
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struct hvutil_transport *hvt, *hvt_found = NULL;
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spin_lock(&hvt_list_lock);
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list_for_each_entry(hvt, &hvt_list, list) {
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if (hvt->cn_id.idx == msg->id.idx &&
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hvt->cn_id.val == msg->id.val) {
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hvt_found = hvt;
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break;
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}
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}
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spin_unlock(&hvt_list_lock);
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if (!hvt_found) {
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pr_warn("hvt_cn_callback: spurious message received!\n");
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return;
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}
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/*
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* Switching to NETLINK mode. Switching to CHARDEV happens when someone
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* opens the device.
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*/
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mutex_lock(&hvt->lock);
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if (hvt->mode == HVUTIL_TRANSPORT_INIT)
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hvt->mode = HVUTIL_TRANSPORT_NETLINK;
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if (hvt->mode == HVUTIL_TRANSPORT_NETLINK)
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hvt_found->on_msg(msg->data, msg->len);
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else
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pr_warn("hvt_cn_callback: unexpected netlink message!\n");
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mutex_unlock(&hvt->lock);
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}
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int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len,
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void (*on_read_cb)(void))
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{
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struct cn_msg *cn_msg;
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int ret = 0;
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if (hvt->mode == HVUTIL_TRANSPORT_INIT ||
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hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
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return -EINVAL;
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} else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
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cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC);
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if (!cn_msg)
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return -ENOMEM;
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cn_msg->id.idx = hvt->cn_id.idx;
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cn_msg->id.val = hvt->cn_id.val;
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cn_msg->len = len;
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memcpy(cn_msg->data, msg, len);
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ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC);
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kfree(cn_msg);
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/*
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* We don't know when netlink messages are delivered but unlike
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* in CHARDEV mode we're not blocked and we can send next
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* messages right away.
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*/
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if (on_read_cb)
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on_read_cb();
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return ret;
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}
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/* HVUTIL_TRANSPORT_CHARDEV */
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mutex_lock(&hvt->lock);
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if (hvt->mode != HVUTIL_TRANSPORT_CHARDEV) {
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ret = -EINVAL;
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goto out_unlock;
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}
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if (hvt->outmsg) {
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/* Previous message wasn't received */
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ret = -EFAULT;
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goto out_unlock;
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}
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hvt->outmsg = kzalloc(len, GFP_KERNEL);
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if (hvt->outmsg) {
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memcpy(hvt->outmsg, msg, len);
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hvt->outmsg_len = len;
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hvt->on_read = on_read_cb;
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wake_up_interruptible(&hvt->outmsg_q);
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} else
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ret = -ENOMEM;
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out_unlock:
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mutex_unlock(&hvt->lock);
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return ret;
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}
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struct hvutil_transport *hvutil_transport_init(const char *name,
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u32 cn_idx, u32 cn_val,
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int (*on_msg)(void *, int),
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void (*on_reset)(void))
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{
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struct hvutil_transport *hvt;
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hvt = kzalloc(sizeof(*hvt), GFP_KERNEL);
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if (!hvt)
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return NULL;
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hvt->cn_id.idx = cn_idx;
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hvt->cn_id.val = cn_val;
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hvt->mdev.minor = MISC_DYNAMIC_MINOR;
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hvt->mdev.name = name;
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hvt->fops.owner = THIS_MODULE;
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hvt->fops.read = hvt_op_read;
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hvt->fops.write = hvt_op_write;
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hvt->fops.poll = hvt_op_poll;
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hvt->fops.open = hvt_op_open;
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hvt->fops.release = hvt_op_release;
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hvt->mdev.fops = &hvt->fops;
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init_waitqueue_head(&hvt->outmsg_q);
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mutex_init(&hvt->lock);
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init_completion(&hvt->release);
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spin_lock(&hvt_list_lock);
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list_add(&hvt->list, &hvt_list);
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spin_unlock(&hvt_list_lock);
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hvt->on_msg = on_msg;
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hvt->on_reset = on_reset;
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if (misc_register(&hvt->mdev))
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goto err_free_hvt;
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/* Use cn_id.idx/cn_id.val to determine if we need to setup netlink */
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if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0 &&
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cn_add_callback(&hvt->cn_id, name, hvt_cn_callback))
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goto err_free_hvt;
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return hvt;
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err_free_hvt:
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spin_lock(&hvt_list_lock);
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list_del(&hvt->list);
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spin_unlock(&hvt_list_lock);
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kfree(hvt);
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return NULL;
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}
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void hvutil_transport_destroy(struct hvutil_transport *hvt)
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{
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int mode_old;
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mutex_lock(&hvt->lock);
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mode_old = hvt->mode;
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hvt->mode = HVUTIL_TRANSPORT_DESTROY;
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wake_up_interruptible(&hvt->outmsg_q);
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mutex_unlock(&hvt->lock);
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/*
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* In case we were in 'chardev' mode we still have an open fd so we
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* have to defer freeing the device. Netlink interface can be freed
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* now.
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*/
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spin_lock(&hvt_list_lock);
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list_del(&hvt->list);
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spin_unlock(&hvt_list_lock);
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if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0)
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cn_del_callback(&hvt->cn_id);
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if (mode_old == HVUTIL_TRANSPORT_CHARDEV)
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wait_for_completion(&hvt->release);
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hvt_transport_free(hvt);
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}
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