| /****************************************************************************** |
| * evtchn.c |
| * |
| * Driver for receiving and demuxing event-channel signals. |
| * |
| * Copyright (c) 2004-2005, K A Fraser |
| * Multi-process extensions Copyright (c) 2004, Steven Smith |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License version 2 |
| * as published by the Free Software Foundation; or, when distributed |
| * separately from the Linux kernel or incorporated into other |
| * software packages, subject to the following license: |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a copy |
| * of this source file (the "Software"), to deal in the Software without |
| * restriction, including without limitation the rights to use, copy, modify, |
| * merge, publish, distribute, sublicense, and/or sell copies of the Software, |
| * and to permit persons to whom the Software is furnished to do so, subject to |
| * the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included in |
| * all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
| * IN THE SOFTWARE. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/sched.h> |
| #include <linux/slab.h> |
| #include <linux/string.h> |
| #include <linux/errno.h> |
| #include <linux/fs.h> |
| #include <linux/miscdevice.h> |
| #include <linux/major.h> |
| #include <linux/proc_fs.h> |
| #include <linux/stat.h> |
| #include <linux/poll.h> |
| #include <linux/irq.h> |
| #include <linux/init.h> |
| #include <linux/mutex.h> |
| #include <linux/cpu.h> |
| |
| #include <xen/xen.h> |
| #include <xen/events.h> |
| #include <xen/evtchn.h> |
| #include <asm/xen/hypervisor.h> |
| |
| struct per_user_data { |
| struct mutex bind_mutex; /* serialize bind/unbind operations */ |
| |
| /* Notification ring, accessed via /dev/xen/evtchn. */ |
| #define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t)) |
| #define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1)) |
| evtchn_port_t *ring; |
| unsigned int ring_cons, ring_prod, ring_overflow; |
| struct mutex ring_cons_mutex; /* protect against concurrent readers */ |
| |
| /* Processes wait on this queue when ring is empty. */ |
| wait_queue_head_t evtchn_wait; |
| struct fasync_struct *evtchn_async_queue; |
| const char *name; |
| }; |
| |
| /* |
| * Who's bound to each port? This is logically an array of struct |
| * per_user_data *, but we encode the current enabled-state in bit 0. |
| */ |
| static unsigned long *port_user; |
| static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */ |
| |
| static inline struct per_user_data *get_port_user(unsigned port) |
| { |
| return (struct per_user_data *)(port_user[port] & ~1); |
| } |
| |
| static inline void set_port_user(unsigned port, struct per_user_data *u) |
| { |
| port_user[port] = (unsigned long)u; |
| } |
| |
| static inline bool get_port_enabled(unsigned port) |
| { |
| return port_user[port] & 1; |
| } |
| |
| static inline void set_port_enabled(unsigned port, bool enabled) |
| { |
| if (enabled) |
| port_user[port] |= 1; |
| else |
| port_user[port] &= ~1; |
| } |
| |
| static irqreturn_t evtchn_interrupt(int irq, void *data) |
| { |
| unsigned int port = (unsigned long)data; |
| struct per_user_data *u; |
| |
| spin_lock(&port_user_lock); |
| |
| u = get_port_user(port); |
| |
| WARN(!get_port_enabled(port), |
| "Interrupt for port %d, but apparently not enabled; per-user %p\n", |
| port, u); |
| |
| disable_irq_nosync(irq); |
| set_port_enabled(port, false); |
| |
| if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) { |
| u->ring[EVTCHN_RING_MASK(u->ring_prod)] = port; |
| wmb(); /* Ensure ring contents visible */ |
| if (u->ring_cons == u->ring_prod++) { |
| wake_up_interruptible(&u->evtchn_wait); |
| kill_fasync(&u->evtchn_async_queue, |
| SIGIO, POLL_IN); |
| } |
| } else |
| u->ring_overflow = 1; |
| |
| spin_unlock(&port_user_lock); |
| |
| return IRQ_HANDLED; |
| } |
| |
| static ssize_t evtchn_read(struct file *file, char __user *buf, |
| size_t count, loff_t *ppos) |
| { |
| int rc; |
| unsigned int c, p, bytes1 = 0, bytes2 = 0; |
| struct per_user_data *u = file->private_data; |
| |
| /* Whole number of ports. */ |
| count &= ~(sizeof(evtchn_port_t)-1); |
| |
| if (count == 0) |
| return 0; |
| |
| if (count > PAGE_SIZE) |
| count = PAGE_SIZE; |
| |
| for (;;) { |
| mutex_lock(&u->ring_cons_mutex); |
| |
| rc = -EFBIG; |
| if (u->ring_overflow) |
| goto unlock_out; |
| |
| c = u->ring_cons; |
| p = u->ring_prod; |
| if (c != p) |
| break; |
| |
| mutex_unlock(&u->ring_cons_mutex); |
| |
| if (file->f_flags & O_NONBLOCK) |
| return -EAGAIN; |
| |
| rc = wait_event_interruptible(u->evtchn_wait, |
| u->ring_cons != u->ring_prod); |
| if (rc) |
| return rc; |
| } |
| |
| /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */ |
| if (((c ^ p) & EVTCHN_RING_SIZE) != 0) { |
| bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) * |
| sizeof(evtchn_port_t); |
| bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t); |
| } else { |
| bytes1 = (p - c) * sizeof(evtchn_port_t); |
| bytes2 = 0; |
| } |
| |
| /* Truncate chunks according to caller's maximum byte count. */ |
| if (bytes1 > count) { |
| bytes1 = count; |
| bytes2 = 0; |
| } else if ((bytes1 + bytes2) > count) { |
| bytes2 = count - bytes1; |
| } |
| |
| rc = -EFAULT; |
| rmb(); /* Ensure that we see the port before we copy it. */ |
| if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) || |
| ((bytes2 != 0) && |
| copy_to_user(&buf[bytes1], &u->ring[0], bytes2))) |
| goto unlock_out; |
| |
| u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t); |
| rc = bytes1 + bytes2; |
| |
| unlock_out: |
| mutex_unlock(&u->ring_cons_mutex); |
| return rc; |
| } |
| |
| static ssize_t evtchn_write(struct file *file, const char __user *buf, |
| size_t count, loff_t *ppos) |
| { |
| int rc, i; |
| evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL); |
| struct per_user_data *u = file->private_data; |
| |
| if (kbuf == NULL) |
| return -ENOMEM; |
| |
| /* Whole number of ports. */ |
| count &= ~(sizeof(evtchn_port_t)-1); |
| |
| rc = 0; |
| if (count == 0) |
| goto out; |
| |
| if (count > PAGE_SIZE) |
| count = PAGE_SIZE; |
| |
| rc = -EFAULT; |
| if (copy_from_user(kbuf, buf, count) != 0) |
| goto out; |
| |
| spin_lock_irq(&port_user_lock); |
| |
| for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) { |
| unsigned port = kbuf[i]; |
| |
| if (port < NR_EVENT_CHANNELS && |
| get_port_user(port) == u && |
| !get_port_enabled(port)) { |
| set_port_enabled(port, true); |
| enable_irq(irq_from_evtchn(port)); |
| } |
| } |
| |
| spin_unlock_irq(&port_user_lock); |
| |
| rc = count; |
| |
| out: |
| free_page((unsigned long)kbuf); |
| return rc; |
| } |
| |
| static int evtchn_bind_to_user(struct per_user_data *u, int port) |
| { |
| int rc = 0; |
| |
| /* |
| * Ports are never reused, so every caller should pass in a |
| * unique port. |
| * |
| * (Locking not necessary because we haven't registered the |
| * interrupt handler yet, and our caller has already |
| * serialized bind operations.) |
| */ |
| BUG_ON(get_port_user(port) != NULL); |
| set_port_user(port, u); |
| set_port_enabled(port, true); /* start enabled */ |
| |
| rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED, |
| u->name, (void *)(unsigned long)port); |
| if (rc >= 0) |
| rc = 0; |
| |
| return rc; |
| } |
| |
| static void evtchn_unbind_from_user(struct per_user_data *u, int port) |
| { |
| int irq = irq_from_evtchn(port); |
| |
| unbind_from_irqhandler(irq, (void *)(unsigned long)port); |
| |
| set_port_user(port, NULL); |
| } |
| |
| static long evtchn_ioctl(struct file *file, |
| unsigned int cmd, unsigned long arg) |
| { |
| int rc; |
| struct per_user_data *u = file->private_data; |
| void __user *uarg = (void __user *) arg; |
| |
| /* Prevent bind from racing with unbind */ |
| mutex_lock(&u->bind_mutex); |
| |
| switch (cmd) { |
| case IOCTL_EVTCHN_BIND_VIRQ: { |
| struct ioctl_evtchn_bind_virq bind; |
| struct evtchn_bind_virq bind_virq; |
| |
| rc = -EFAULT; |
| if (copy_from_user(&bind, uarg, sizeof(bind))) |
| break; |
| |
| bind_virq.virq = bind.virq; |
| bind_virq.vcpu = 0; |
| rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq, |
| &bind_virq); |
| if (rc != 0) |
| break; |
| |
| rc = evtchn_bind_to_user(u, bind_virq.port); |
| if (rc == 0) |
| rc = bind_virq.port; |
| break; |
| } |
| |
| case IOCTL_EVTCHN_BIND_INTERDOMAIN: { |
| struct ioctl_evtchn_bind_interdomain bind; |
| struct evtchn_bind_interdomain bind_interdomain; |
| |
| rc = -EFAULT; |
| if (copy_from_user(&bind, uarg, sizeof(bind))) |
| break; |
| |
| bind_interdomain.remote_dom = bind.remote_domain; |
| bind_interdomain.remote_port = bind.remote_port; |
| rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain, |
| &bind_interdomain); |
| if (rc != 0) |
| break; |
| |
| rc = evtchn_bind_to_user(u, bind_interdomain.local_port); |
| if (rc == 0) |
| rc = bind_interdomain.local_port; |
| break; |
| } |
| |
| case IOCTL_EVTCHN_BIND_UNBOUND_PORT: { |
| struct ioctl_evtchn_bind_unbound_port bind; |
| struct evtchn_alloc_unbound alloc_unbound; |
| |
| rc = -EFAULT; |
| if (copy_from_user(&bind, uarg, sizeof(bind))) |
| break; |
| |
| alloc_unbound.dom = DOMID_SELF; |
| alloc_unbound.remote_dom = bind.remote_domain; |
| rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, |
| &alloc_unbound); |
| if (rc != 0) |
| break; |
| |
| rc = evtchn_bind_to_user(u, alloc_unbound.port); |
| if (rc == 0) |
| rc = alloc_unbound.port; |
| break; |
| } |
| |
| case IOCTL_EVTCHN_UNBIND: { |
| struct ioctl_evtchn_unbind unbind; |
| |
| rc = -EFAULT; |
| if (copy_from_user(&unbind, uarg, sizeof(unbind))) |
| break; |
| |
| rc = -EINVAL; |
| if (unbind.port >= NR_EVENT_CHANNELS) |
| break; |
| |
| spin_lock_irq(&port_user_lock); |
| |
| rc = -ENOTCONN; |
| if (get_port_user(unbind.port) != u) { |
| spin_unlock_irq(&port_user_lock); |
| break; |
| } |
| |
| disable_irq(irq_from_evtchn(unbind.port)); |
| |
| spin_unlock_irq(&port_user_lock); |
| |
| evtchn_unbind_from_user(u, unbind.port); |
| |
| rc = 0; |
| break; |
| } |
| |
| case IOCTL_EVTCHN_NOTIFY: { |
| struct ioctl_evtchn_notify notify; |
| |
| rc = -EFAULT; |
| if (copy_from_user(¬ify, uarg, sizeof(notify))) |
| break; |
| |
| if (notify.port >= NR_EVENT_CHANNELS) { |
| rc = -EINVAL; |
| } else if (get_port_user(notify.port) != u) { |
| rc = -ENOTCONN; |
| } else { |
| notify_remote_via_evtchn(notify.port); |
| rc = 0; |
| } |
| break; |
| } |
| |
| case IOCTL_EVTCHN_RESET: { |
| /* Initialise the ring to empty. Clear errors. */ |
| mutex_lock(&u->ring_cons_mutex); |
| spin_lock_irq(&port_user_lock); |
| u->ring_cons = u->ring_prod = u->ring_overflow = 0; |
| spin_unlock_irq(&port_user_lock); |
| mutex_unlock(&u->ring_cons_mutex); |
| rc = 0; |
| break; |
| } |
| |
| default: |
| rc = -ENOSYS; |
| break; |
| } |
| mutex_unlock(&u->bind_mutex); |
| |
| return rc; |
| } |
| |
| static unsigned int evtchn_poll(struct file *file, poll_table *wait) |
| { |
| unsigned int mask = POLLOUT | POLLWRNORM; |
| struct per_user_data *u = file->private_data; |
| |
| poll_wait(file, &u->evtchn_wait, wait); |
| if (u->ring_cons != u->ring_prod) |
| mask |= POLLIN | POLLRDNORM; |
| if (u->ring_overflow) |
| mask = POLLERR; |
| return mask; |
| } |
| |
| static int evtchn_fasync(int fd, struct file *filp, int on) |
| { |
| struct per_user_data *u = filp->private_data; |
| return fasync_helper(fd, filp, on, &u->evtchn_async_queue); |
| } |
| |
| static int evtchn_open(struct inode *inode, struct file *filp) |
| { |
| struct per_user_data *u; |
| |
| u = kzalloc(sizeof(*u), GFP_KERNEL); |
| if (u == NULL) |
| return -ENOMEM; |
| |
| u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm); |
| if (u->name == NULL) { |
| kfree(u); |
| return -ENOMEM; |
| } |
| |
| init_waitqueue_head(&u->evtchn_wait); |
| |
| u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL); |
| if (u->ring == NULL) { |
| kfree(u->name); |
| kfree(u); |
| return -ENOMEM; |
| } |
| |
| mutex_init(&u->bind_mutex); |
| mutex_init(&u->ring_cons_mutex); |
| |
| filp->private_data = u; |
| |
| return nonseekable_open(inode, filp); |
| } |
| |
| static int evtchn_release(struct inode *inode, struct file *filp) |
| { |
| int i; |
| struct per_user_data *u = filp->private_data; |
| |
| spin_lock_irq(&port_user_lock); |
| |
| free_page((unsigned long)u->ring); |
| |
| for (i = 0; i < NR_EVENT_CHANNELS; i++) { |
| if (get_port_user(i) != u) |
| continue; |
| |
| disable_irq(irq_from_evtchn(i)); |
| } |
| |
| spin_unlock_irq(&port_user_lock); |
| |
| for (i = 0; i < NR_EVENT_CHANNELS; i++) { |
| if (get_port_user(i) != u) |
| continue; |
| |
| evtchn_unbind_from_user(get_port_user(i), i); |
| } |
| |
| kfree(u->name); |
| kfree(u); |
| |
| return 0; |
| } |
| |
| static const struct file_operations evtchn_fops = { |
| .owner = THIS_MODULE, |
| .read = evtchn_read, |
| .write = evtchn_write, |
| .unlocked_ioctl = evtchn_ioctl, |
| .poll = evtchn_poll, |
| .fasync = evtchn_fasync, |
| .open = evtchn_open, |
| .release = evtchn_release, |
| .llseek = no_llseek, |
| }; |
| |
| static struct miscdevice evtchn_miscdev = { |
| .minor = MISC_DYNAMIC_MINOR, |
| .name = "xen/evtchn", |
| .fops = &evtchn_fops, |
| }; |
| static int __init evtchn_init(void) |
| { |
| int err; |
| |
| if (!xen_domain()) |
| return -ENODEV; |
| |
| port_user = kcalloc(NR_EVENT_CHANNELS, sizeof(*port_user), GFP_KERNEL); |
| if (port_user == NULL) |
| return -ENOMEM; |
| |
| spin_lock_init(&port_user_lock); |
| |
| /* Create '/dev/misc/evtchn'. */ |
| err = misc_register(&evtchn_miscdev); |
| if (err != 0) { |
| printk(KERN_ALERT "Could not register /dev/misc/evtchn\n"); |
| return err; |
| } |
| |
| printk(KERN_INFO "Event-channel device installed.\n"); |
| |
| return 0; |
| } |
| |
| static void __exit evtchn_cleanup(void) |
| { |
| kfree(port_user); |
| port_user = NULL; |
| |
| misc_deregister(&evtchn_miscdev); |
| } |
| |
| module_init(evtchn_init); |
| module_exit(evtchn_cleanup); |
| |
| MODULE_LICENSE("GPL"); |