![Juergen Gross](/assets/img/avatar_default.png)
Instead of disabling the irq when an event is received and enabling it again when handled by the user process use the lateeoi model. This is part of XSA-332. Cc: stable@vger.kernel.org Reported-by: Julien Grall <julien@xen.org> Signed-off-by: Juergen Gross <jgross@suse.com> Tested-by: Stefano Stabellini <sstabellini@kernel.org> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Reviewed-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Wei Liu <wl@xen.org>
735 lines
17 KiB
C
735 lines
17 KiB
C
/******************************************************************************
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* evtchn.c
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*
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* Driver for receiving and demuxing event-channel signals.
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*
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* Copyright (c) 2004-2005, K A Fraser
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* Multi-process extensions Copyright (c) 2004, Steven Smith
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation; or, when distributed
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* separately from the Linux kernel or incorporated into other
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* software packages, subject to the following license:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this source file (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy, modify,
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* merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/miscdevice.h>
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#include <linux/major.h>
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#include <linux/proc_fs.h>
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#include <linux/stat.h>
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#include <linux/poll.h>
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#include <linux/irq.h>
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#include <linux/init.h>
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#include <linux/mutex.h>
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#include <linux/cpu.h>
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#include <linux/mm.h>
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#include <linux/vmalloc.h>
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#include <xen/xen.h>
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#include <xen/events.h>
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#include <xen/evtchn.h>
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#include <xen/xen-ops.h>
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#include <asm/xen/hypervisor.h>
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struct per_user_data {
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struct mutex bind_mutex; /* serialize bind/unbind operations */
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struct rb_root evtchns;
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unsigned int nr_evtchns;
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/* Notification ring, accessed via /dev/xen/evtchn. */
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unsigned int ring_size;
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evtchn_port_t *ring;
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unsigned int ring_cons, ring_prod, ring_overflow;
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struct mutex ring_cons_mutex; /* protect against concurrent readers */
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spinlock_t ring_prod_lock; /* product against concurrent interrupts */
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/* Processes wait on this queue when ring is empty. */
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wait_queue_head_t evtchn_wait;
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struct fasync_struct *evtchn_async_queue;
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const char *name;
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domid_t restrict_domid;
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};
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#define UNRESTRICTED_DOMID ((domid_t)-1)
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struct user_evtchn {
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struct rb_node node;
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struct per_user_data *user;
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evtchn_port_t port;
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bool enabled;
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};
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static void evtchn_free_ring(evtchn_port_t *ring)
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{
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kvfree(ring);
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}
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static unsigned int evtchn_ring_offset(struct per_user_data *u,
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unsigned int idx)
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{
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return idx & (u->ring_size - 1);
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}
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static evtchn_port_t *evtchn_ring_entry(struct per_user_data *u,
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unsigned int idx)
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{
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return u->ring + evtchn_ring_offset(u, idx);
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}
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static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
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{
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struct rb_node **new = &(u->evtchns.rb_node), *parent = NULL;
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u->nr_evtchns++;
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while (*new) {
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struct user_evtchn *this;
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this = rb_entry(*new, struct user_evtchn, node);
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parent = *new;
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if (this->port < evtchn->port)
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new = &((*new)->rb_left);
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else if (this->port > evtchn->port)
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new = &((*new)->rb_right);
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else
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return -EEXIST;
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}
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/* Add new node and rebalance tree. */
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rb_link_node(&evtchn->node, parent, new);
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rb_insert_color(&evtchn->node, &u->evtchns);
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return 0;
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}
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static void del_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
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{
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u->nr_evtchns--;
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rb_erase(&evtchn->node, &u->evtchns);
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kfree(evtchn);
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}
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static struct user_evtchn *find_evtchn(struct per_user_data *u,
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evtchn_port_t port)
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{
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struct rb_node *node = u->evtchns.rb_node;
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while (node) {
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struct user_evtchn *evtchn;
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evtchn = rb_entry(node, struct user_evtchn, node);
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if (evtchn->port < port)
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node = node->rb_left;
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else if (evtchn->port > port)
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node = node->rb_right;
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else
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return evtchn;
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}
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return NULL;
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}
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static irqreturn_t evtchn_interrupt(int irq, void *data)
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{
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struct user_evtchn *evtchn = data;
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struct per_user_data *u = evtchn->user;
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WARN(!evtchn->enabled,
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"Interrupt for port %u, but apparently not enabled; per-user %p\n",
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evtchn->port, u);
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evtchn->enabled = false;
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spin_lock(&u->ring_prod_lock);
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if ((u->ring_prod - u->ring_cons) < u->ring_size) {
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*evtchn_ring_entry(u, u->ring_prod) = evtchn->port;
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wmb(); /* Ensure ring contents visible */
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if (u->ring_cons == u->ring_prod++) {
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wake_up_interruptible(&u->evtchn_wait);
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kill_fasync(&u->evtchn_async_queue,
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SIGIO, POLL_IN);
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}
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} else
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u->ring_overflow = 1;
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spin_unlock(&u->ring_prod_lock);
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return IRQ_HANDLED;
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}
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static ssize_t evtchn_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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int rc;
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unsigned int c, p, bytes1 = 0, bytes2 = 0;
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struct per_user_data *u = file->private_data;
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/* Whole number of ports. */
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count &= ~(sizeof(evtchn_port_t)-1);
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if (count == 0)
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return 0;
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if (count > PAGE_SIZE)
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count = PAGE_SIZE;
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for (;;) {
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mutex_lock(&u->ring_cons_mutex);
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rc = -EFBIG;
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if (u->ring_overflow)
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goto unlock_out;
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c = u->ring_cons;
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p = u->ring_prod;
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if (c != p)
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break;
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mutex_unlock(&u->ring_cons_mutex);
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if (file->f_flags & O_NONBLOCK)
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return -EAGAIN;
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rc = wait_event_interruptible(u->evtchn_wait,
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u->ring_cons != u->ring_prod);
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if (rc)
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return rc;
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}
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/* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
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if (((c ^ p) & u->ring_size) != 0) {
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bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) *
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sizeof(evtchn_port_t);
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bytes2 = evtchn_ring_offset(u, p) * sizeof(evtchn_port_t);
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} else {
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bytes1 = (p - c) * sizeof(evtchn_port_t);
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bytes2 = 0;
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}
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/* Truncate chunks according to caller's maximum byte count. */
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if (bytes1 > count) {
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bytes1 = count;
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bytes2 = 0;
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} else if ((bytes1 + bytes2) > count) {
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bytes2 = count - bytes1;
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}
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rc = -EFAULT;
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rmb(); /* Ensure that we see the port before we copy it. */
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if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) ||
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((bytes2 != 0) &&
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copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
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goto unlock_out;
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u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);
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rc = bytes1 + bytes2;
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unlock_out:
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mutex_unlock(&u->ring_cons_mutex);
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return rc;
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}
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static ssize_t evtchn_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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int rc, i;
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evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
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struct per_user_data *u = file->private_data;
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if (kbuf == NULL)
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return -ENOMEM;
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/* Whole number of ports. */
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count &= ~(sizeof(evtchn_port_t)-1);
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rc = 0;
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if (count == 0)
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goto out;
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if (count > PAGE_SIZE)
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count = PAGE_SIZE;
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rc = -EFAULT;
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if (copy_from_user(kbuf, buf, count) != 0)
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goto out;
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mutex_lock(&u->bind_mutex);
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for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
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evtchn_port_t port = kbuf[i];
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struct user_evtchn *evtchn;
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evtchn = find_evtchn(u, port);
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if (evtchn && !evtchn->enabled) {
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evtchn->enabled = true;
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xen_irq_lateeoi(irq_from_evtchn(port), 0);
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}
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}
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mutex_unlock(&u->bind_mutex);
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rc = count;
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out:
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free_page((unsigned long)kbuf);
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return rc;
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}
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static int evtchn_resize_ring(struct per_user_data *u)
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{
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unsigned int new_size;
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evtchn_port_t *new_ring, *old_ring;
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/*
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* Ensure the ring is large enough to capture all possible
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* events. i.e., one free slot for each bound event.
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*/
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if (u->nr_evtchns <= u->ring_size)
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return 0;
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if (u->ring_size == 0)
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new_size = 64;
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else
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new_size = 2 * u->ring_size;
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new_ring = kvmalloc_array(new_size, sizeof(*new_ring), GFP_KERNEL);
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if (!new_ring)
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return -ENOMEM;
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old_ring = u->ring;
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/*
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* Access to the ring contents is serialized by either the
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* prod /or/ cons lock so take both when resizing.
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*/
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mutex_lock(&u->ring_cons_mutex);
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spin_lock_irq(&u->ring_prod_lock);
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/*
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* Copy the old ring contents to the new ring.
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*
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* To take care of wrapping, a full ring, and the new index
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* pointing into the second half, simply copy the old contents
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* twice.
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*
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* +---------+ +------------------+
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* |34567 12| -> |34567 1234567 12|
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* +-----p-c-+ +-------c------p---+
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*/
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memcpy(new_ring, old_ring, u->ring_size * sizeof(*u->ring));
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memcpy(new_ring + u->ring_size, old_ring,
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u->ring_size * sizeof(*u->ring));
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u->ring = new_ring;
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u->ring_size = new_size;
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spin_unlock_irq(&u->ring_prod_lock);
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mutex_unlock(&u->ring_cons_mutex);
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evtchn_free_ring(old_ring);
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return 0;
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}
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static int evtchn_bind_to_user(struct per_user_data *u, evtchn_port_t port)
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{
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struct user_evtchn *evtchn;
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struct evtchn_close close;
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int rc = 0;
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/*
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* Ports are never reused, so every caller should pass in a
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* unique port.
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*
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* (Locking not necessary because we haven't registered the
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* interrupt handler yet, and our caller has already
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* serialized bind operations.)
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*/
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evtchn = kzalloc(sizeof(*evtchn), GFP_KERNEL);
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if (!evtchn)
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return -ENOMEM;
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evtchn->user = u;
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evtchn->port = port;
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evtchn->enabled = true; /* start enabled */
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rc = add_evtchn(u, evtchn);
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if (rc < 0)
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goto err;
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rc = evtchn_resize_ring(u);
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if (rc < 0)
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goto err;
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rc = bind_evtchn_to_irqhandler_lateeoi(port, evtchn_interrupt, 0,
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u->name, evtchn);
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if (rc < 0)
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goto err;
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rc = evtchn_make_refcounted(port);
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return rc;
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err:
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/* bind failed, should close the port now */
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close.port = port;
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if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
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BUG();
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del_evtchn(u, evtchn);
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return rc;
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}
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static void evtchn_unbind_from_user(struct per_user_data *u,
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struct user_evtchn *evtchn)
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{
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int irq = irq_from_evtchn(evtchn->port);
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BUG_ON(irq < 0);
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unbind_from_irqhandler(irq, evtchn);
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del_evtchn(u, evtchn);
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}
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static DEFINE_PER_CPU(int, bind_last_selected_cpu);
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static void evtchn_bind_interdom_next_vcpu(evtchn_port_t evtchn)
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{
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unsigned int selected_cpu, irq;
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struct irq_desc *desc;
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unsigned long flags;
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irq = irq_from_evtchn(evtchn);
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desc = irq_to_desc(irq);
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if (!desc)
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return;
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raw_spin_lock_irqsave(&desc->lock, flags);
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selected_cpu = this_cpu_read(bind_last_selected_cpu);
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selected_cpu = cpumask_next_and(selected_cpu,
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desc->irq_common_data.affinity, cpu_online_mask);
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if (unlikely(selected_cpu >= nr_cpu_ids))
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selected_cpu = cpumask_first_and(desc->irq_common_data.affinity,
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cpu_online_mask);
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this_cpu_write(bind_last_selected_cpu, selected_cpu);
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/* unmask expects irqs to be disabled */
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xen_set_affinity_evtchn(desc, selected_cpu);
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raw_spin_unlock_irqrestore(&desc->lock, flags);
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}
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static long evtchn_ioctl(struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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int rc;
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struct per_user_data *u = file->private_data;
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void __user *uarg = (void __user *) arg;
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/* Prevent bind from racing with unbind */
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mutex_lock(&u->bind_mutex);
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switch (cmd) {
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case IOCTL_EVTCHN_BIND_VIRQ: {
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struct ioctl_evtchn_bind_virq bind;
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struct evtchn_bind_virq bind_virq;
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rc = -EACCES;
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if (u->restrict_domid != UNRESTRICTED_DOMID)
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break;
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rc = -EFAULT;
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if (copy_from_user(&bind, uarg, sizeof(bind)))
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break;
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bind_virq.virq = bind.virq;
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bind_virq.vcpu = xen_vcpu_nr(0);
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rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
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&bind_virq);
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if (rc != 0)
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break;
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rc = evtchn_bind_to_user(u, bind_virq.port);
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if (rc == 0)
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rc = bind_virq.port;
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break;
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}
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case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
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struct ioctl_evtchn_bind_interdomain bind;
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struct evtchn_bind_interdomain bind_interdomain;
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rc = -EFAULT;
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if (copy_from_user(&bind, uarg, sizeof(bind)))
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break;
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rc = -EACCES;
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if (u->restrict_domid != UNRESTRICTED_DOMID &&
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u->restrict_domid != bind.remote_domain)
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break;
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bind_interdomain.remote_dom = bind.remote_domain;
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bind_interdomain.remote_port = bind.remote_port;
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rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
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&bind_interdomain);
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if (rc != 0)
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break;
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rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
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if (rc == 0) {
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rc = bind_interdomain.local_port;
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evtchn_bind_interdom_next_vcpu(rc);
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}
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break;
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|
}
|
|
|
|
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);
|
|
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_NOTIFY: {
|
|
struct ioctl_evtchn_notify notify;
|
|
struct user_evtchn *evtchn;
|
|
|
|
rc = -EFAULT;
|
|
if (copy_from_user(¬ify, 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);
|
|
u->ring_cons = u->ring_prod = 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 (u->ring_cons != 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");
|