summaryrefslogtreecommitdiffstats
path: root/drivers/xen/evtchn.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/xen/evtchn.c')
-rw-r--r--drivers/xen/evtchn.c726
1 files changed, 726 insertions, 0 deletions
diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
new file mode 100644
index 0000000000..9139a7364d
--- /dev/null
+++ b/drivers/xen/evtchn.c
@@ -0,0 +1,726 @@
+/******************************************************************************
+ * 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.
+ */
+
+#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
+
+#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 <linux/mm.h>
+#include <linux/vmalloc.h>
+
+#include <xen/xen.h>
+#include <xen/events.h>
+#include <xen/evtchn.h>
+#include <xen/xen-ops.h>
+#include <asm/xen/hypervisor.h>
+
+struct per_user_data {
+ struct mutex bind_mutex; /* serialize bind/unbind operations */
+ struct rb_root evtchns;
+ unsigned int nr_evtchns;
+
+ /* Notification ring, accessed via /dev/xen/evtchn. */
+ unsigned int ring_size;
+ evtchn_port_t *ring;
+ unsigned int ring_cons, ring_prod, ring_overflow;
+ struct mutex ring_cons_mutex; /* protect against concurrent readers */
+ spinlock_t ring_prod_lock; /* product against concurrent interrupts */
+
+ /* Processes wait on this queue when ring is empty. */
+ wait_queue_head_t evtchn_wait;
+ struct fasync_struct *evtchn_async_queue;
+ const char *name;
+
+ domid_t restrict_domid;
+};
+
+#define UNRESTRICTED_DOMID ((domid_t)-1)
+
+struct user_evtchn {
+ struct rb_node node;
+ struct per_user_data *user;
+ evtchn_port_t port;
+ bool enabled;
+};
+
+static void evtchn_free_ring(evtchn_port_t *ring)
+{
+ kvfree(ring);
+}
+
+static unsigned int evtchn_ring_offset(struct per_user_data *u,
+ unsigned int idx)
+{
+ return idx & (u->ring_size - 1);
+}
+
+static evtchn_port_t *evtchn_ring_entry(struct per_user_data *u,
+ unsigned int idx)
+{
+ return u->ring + evtchn_ring_offset(u, idx);
+}
+
+static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
+{
+ struct rb_node **new = &(u->evtchns.rb_node), *parent = NULL;
+
+ u->nr_evtchns++;
+
+ while (*new) {
+ struct user_evtchn *this;
+
+ this = rb_entry(*new, struct user_evtchn, node);
+
+ parent = *new;
+ if (this->port < evtchn->port)
+ new = &((*new)->rb_left);
+ else if (this->port > evtchn->port)
+ new = &((*new)->rb_right);
+ else
+ return -EEXIST;
+ }
+
+ /* Add new node and rebalance tree. */
+ rb_link_node(&evtchn->node, parent, new);
+ rb_insert_color(&evtchn->node, &u->evtchns);
+
+ return 0;
+}
+
+static void del_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
+{
+ u->nr_evtchns--;
+ rb_erase(&evtchn->node, &u->evtchns);
+ kfree(evtchn);
+}
+
+static struct user_evtchn *find_evtchn(struct per_user_data *u,
+ evtchn_port_t port)
+{
+ struct rb_node *node = u->evtchns.rb_node;
+
+ while (node) {
+ struct user_evtchn *evtchn;
+
+ evtchn = rb_entry(node, struct user_evtchn, node);
+
+ if (evtchn->port < port)
+ node = node->rb_left;
+ else if (evtchn->port > port)
+ node = node->rb_right;
+ else
+ return evtchn;
+ }
+ return NULL;
+}
+
+static irqreturn_t evtchn_interrupt(int irq, void *data)
+{
+ struct user_evtchn *evtchn = data;
+ struct per_user_data *u = evtchn->user;
+ unsigned int prod, cons;
+
+ WARN(!evtchn->enabled,
+ "Interrupt for port %u, but apparently not enabled; per-user %p\n",
+ evtchn->port, u);
+
+ evtchn->enabled = false;
+
+ spin_lock(&u->ring_prod_lock);
+
+ prod = READ_ONCE(u->ring_prod);
+ cons = READ_ONCE(u->ring_cons);
+
+ if ((prod - cons) < u->ring_size) {
+ *evtchn_ring_entry(u, prod) = evtchn->port;
+ smp_wmb(); /* Ensure ring contents visible */
+ WRITE_ONCE(u->ring_prod, prod + 1);
+ if (cons == prod) {
+ wake_up_interruptible(&u->evtchn_wait);
+ kill_fasync(&u->evtchn_async_queue,
+ SIGIO, POLL_IN);
+ }
+ } else
+ u->ring_overflow = 1;
+
+ spin_unlock(&u->ring_prod_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 = READ_ONCE(u->ring_cons);
+ p = READ_ONCE(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,
+ READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod));
+ if (rc)
+ return rc;
+ }
+
+ /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
+ if (((c ^ p) & u->ring_size) != 0) {
+ bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) *
+ sizeof(evtchn_port_t);
+ bytes2 = evtchn_ring_offset(u, 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;
+ smp_rmb(); /* Ensure that we see the port before we copy it. */
+ if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) ||
+ ((bytes2 != 0) &&
+ copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
+ goto unlock_out;
+
+ WRITE_ONCE(u->ring_cons, c + (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;
+
+ mutex_lock(&u->bind_mutex);
+
+ for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
+ evtchn_port_t port = kbuf[i];
+ struct user_evtchn *evtchn;
+
+ evtchn = find_evtchn(u, port);
+ if (evtchn && !evtchn->enabled) {
+ evtchn->enabled = true;
+ xen_irq_lateeoi(irq_from_evtchn(port), 0);
+ }
+ }
+
+ mutex_unlock(&u->bind_mutex);
+
+ rc = count;
+
+ out:
+ free_page((unsigned long)kbuf);
+ return rc;
+}
+
+static int evtchn_resize_ring(struct per_user_data *u)
+{
+ unsigned int new_size;
+ evtchn_port_t *new_ring, *old_ring;
+
+ /*
+ * Ensure the ring is large enough to capture all possible
+ * events. i.e., one free slot for each bound event.
+ */
+ if (u->nr_evtchns <= u->ring_size)
+ return 0;
+
+ if (u->ring_size == 0)
+ new_size = 64;
+ else
+ new_size = 2 * u->ring_size;
+
+ new_ring = kvmalloc_array(new_size, sizeof(*new_ring), GFP_KERNEL);
+ if (!new_ring)
+ return -ENOMEM;
+
+ old_ring = u->ring;
+
+ /*
+ * Access to the ring contents is serialized by either the
+ * prod /or/ cons lock so take both when resizing.
+ */
+ mutex_lock(&u->ring_cons_mutex);
+ spin_lock_irq(&u->ring_prod_lock);
+
+ /*
+ * Copy the old ring contents to the new ring.
+ *
+ * To take care of wrapping, a full ring, and the new index
+ * pointing into the second half, simply copy the old contents
+ * twice.
+ *
+ * +---------+ +------------------+
+ * |34567 12| -> |34567 1234567 12|
+ * +-----p-c-+ +-------c------p---+
+ */
+ memcpy(new_ring, old_ring, u->ring_size * sizeof(*u->ring));
+ memcpy(new_ring + u->ring_size, old_ring,
+ u->ring_size * sizeof(*u->ring));
+
+ u->ring = new_ring;
+ u->ring_size = new_size;
+
+ spin_unlock_irq(&u->ring_prod_lock);
+ mutex_unlock(&u->ring_cons_mutex);
+
+ evtchn_free_ring(old_ring);
+
+ return 0;
+}
+
+static int evtchn_bind_to_user(struct per_user_data *u, evtchn_port_t port,
+ bool is_static)
+{
+ struct user_evtchn *evtchn;
+ 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.)
+ */
+
+ evtchn = kzalloc(sizeof(*evtchn), GFP_KERNEL);
+ if (!evtchn)
+ return -ENOMEM;
+
+ evtchn->user = u;
+ evtchn->port = port;
+ evtchn->enabled = true; /* start enabled */
+
+ rc = add_evtchn(u, evtchn);
+ if (rc < 0)
+ goto err;
+
+ rc = evtchn_resize_ring(u);
+ if (rc < 0)
+ goto err;
+
+ rc = bind_evtchn_to_irqhandler_lateeoi(port, evtchn_interrupt, 0,
+ u->name, evtchn);
+ if (rc < 0)
+ goto err;
+
+ rc = evtchn_make_refcounted(port, is_static);
+ return rc;
+
+err:
+ /* bind failed, should close the port now */
+ if (!is_static)
+ xen_evtchn_close(port);
+
+ del_evtchn(u, evtchn);
+ return rc;
+}
+
+static void evtchn_unbind_from_user(struct per_user_data *u,
+ struct user_evtchn *evtchn)
+{
+ int irq = irq_from_evtchn(evtchn->port);
+
+ BUG_ON(irq < 0);
+
+ unbind_from_irqhandler(irq, evtchn);
+
+ del_evtchn(u, evtchn);
+}
+
+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 = -EACCES;
+ if (u->restrict_domid != UNRESTRICTED_DOMID)
+ break;
+
+ rc = -EFAULT;
+ if (copy_from_user(&bind, uarg, sizeof(bind)))
+ break;
+
+ bind_virq.virq = bind.virq;
+ bind_virq.vcpu = xen_vcpu_nr(0);
+ rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
+ &bind_virq);
+ if (rc != 0)
+ break;
+
+ rc = evtchn_bind_to_user(u, bind_virq.port, false);
+ 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;
+
+ rc = -EACCES;
+ if (u->restrict_domid != UNRESTRICTED_DOMID &&
+ u->restrict_domid != bind.remote_domain)
+ 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, false);
+ 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 = -EACCES;
+ if (u->restrict_domid != UNRESTRICTED_DOMID)
+ break;
+
+ 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, false);
+ if (rc == 0)
+ rc = alloc_unbound.port;
+ break;
+ }
+
+ case IOCTL_EVTCHN_UNBIND: {
+ struct ioctl_evtchn_unbind unbind;
+ struct user_evtchn *evtchn;
+
+ rc = -EFAULT;
+ if (copy_from_user(&unbind, uarg, sizeof(unbind)))
+ break;
+
+ rc = -EINVAL;
+ if (unbind.port >= xen_evtchn_nr_channels())
+ break;
+
+ rc = -ENOTCONN;
+ evtchn = find_evtchn(u, unbind.port);
+ if (!evtchn)
+ break;
+
+ disable_irq(irq_from_evtchn(unbind.port));
+ evtchn_unbind_from_user(u, evtchn);
+ rc = 0;
+ break;
+ }
+
+ case IOCTL_EVTCHN_BIND_STATIC: {
+ struct ioctl_evtchn_bind bind;
+ struct user_evtchn *evtchn;
+
+ rc = -EFAULT;
+ if (copy_from_user(&bind, uarg, sizeof(bind)))
+ break;
+
+ rc = -EISCONN;
+ evtchn = find_evtchn(u, bind.port);
+ if (evtchn)
+ break;
+
+ rc = evtchn_bind_to_user(u, bind.port, true);
+ break;
+ }
+
+ case IOCTL_EVTCHN_NOTIFY: {
+ struct ioctl_evtchn_notify notify;
+ struct user_evtchn *evtchn;
+
+ rc = -EFAULT;
+ if (copy_from_user(&notify, uarg, sizeof(notify)))
+ break;
+
+ rc = -ENOTCONN;
+ evtchn = find_evtchn(u, notify.port);
+ if (evtchn) {
+ 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(&u->ring_prod_lock);
+ WRITE_ONCE(u->ring_cons, 0);
+ WRITE_ONCE(u->ring_prod, 0);
+ u->ring_overflow = 0;
+ spin_unlock_irq(&u->ring_prod_lock);
+ mutex_unlock(&u->ring_cons_mutex);
+ rc = 0;
+ break;
+ }
+
+ case IOCTL_EVTCHN_RESTRICT_DOMID: {
+ struct ioctl_evtchn_restrict_domid ierd;
+
+ rc = -EACCES;
+ if (u->restrict_domid != UNRESTRICTED_DOMID)
+ break;
+
+ rc = -EFAULT;
+ if (copy_from_user(&ierd, uarg, sizeof(ierd)))
+ break;
+
+ rc = -EINVAL;
+ if (ierd.domid == 0 || ierd.domid >= DOMID_FIRST_RESERVED)
+ break;
+
+ u->restrict_domid = ierd.domid;
+ rc = 0;
+
+ break;
+ }
+
+ default:
+ rc = -ENOSYS;
+ break;
+ }
+ mutex_unlock(&u->bind_mutex);
+
+ return rc;
+}
+
+static __poll_t evtchn_poll(struct file *file, poll_table *wait)
+{
+ __poll_t mask = EPOLLOUT | EPOLLWRNORM;
+ struct per_user_data *u = file->private_data;
+
+ poll_wait(file, &u->evtchn_wait, wait);
+ if (READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod))
+ mask |= EPOLLIN | EPOLLRDNORM;
+ if (u->ring_overflow)
+ mask = EPOLLERR;
+ 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);
+
+ mutex_init(&u->bind_mutex);
+ mutex_init(&u->ring_cons_mutex);
+ spin_lock_init(&u->ring_prod_lock);
+
+ u->restrict_domid = UNRESTRICTED_DOMID;
+
+ filp->private_data = u;
+
+ return stream_open(inode, filp);
+}
+
+static int evtchn_release(struct inode *inode, struct file *filp)
+{
+ struct per_user_data *u = filp->private_data;
+ struct rb_node *node;
+
+ while ((node = u->evtchns.rb_node)) {
+ struct user_evtchn *evtchn;
+
+ evtchn = rb_entry(node, struct user_evtchn, node);
+ disable_irq(irq_from_evtchn(evtchn->port));
+ evtchn_unbind_from_user(u, evtchn);
+ }
+
+ evtchn_free_ring(u->ring);
+ 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;
+
+ /* Create '/dev/xen/evtchn'. */
+ err = misc_register(&evtchn_miscdev);
+ if (err != 0) {
+ pr_err("Could not register /dev/xen/evtchn\n");
+ return err;
+ }
+
+ pr_info("Event-channel device installed\n");
+
+ return 0;
+}
+
+static void __exit evtchn_cleanup(void)
+{
+ misc_deregister(&evtchn_miscdev);
+}
+
+module_init(evtchn_init);
+module_exit(evtchn_cleanup);
+
+MODULE_LICENSE("GPL");
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-17 12:17:09 +0000