freebsd-skq/sys/dev/xen/evtchn/evtchn_dev.c
royger 4d53ee84fa xen: import a proper event channel user-space device
The user-space event channel device is used by applications to receive
and send event channel interrupts. This device is based on the Linux
evtchn device.

Sponsored by: Citrix Systems R&D

xen/evtchn/evtchn_dev.c:
 - Remove the old event channel device, which was already disabled in
   the build system.

dev/xen/evtchn/evtchn_dev.c:
 - Import a new event channel device based on the one present in
   Linux.
 - This device allows the following operations:
   - Bind VIRQ event channels (ioctl).
   - Bind regular event channels (ioctl).
   - Create and bind new event channels (ioctl).
   - Unbind event channels (ioctl).
   - Send notifications to event channels (ioctl).
   - Reset the device shared memory ring (ioctl).
   - Unmask event channels (write).
   - Receive event channel upcalls (read).
 - The new code is MP safe, and can be used concurrently.

conf/files:
 - Add the new device to the build system.
2014-10-22 16:57:11 +00:00

608 lines
14 KiB
C

/******************************************************************************
* 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
* FreeBSD port Copyright (c) 2014, Roger Pau Monné
* Fetched from git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
* File: drivers/xen/evtchn.c
* Git commit: 0dc0064add422bc0ef5165ebe9ece3052bbd457d
*
* 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/bus.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sx.h>
#include <sys/selinfo.h>
#include <sys/poll.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/ioccom.h>
#include <sys/rman.h>
#include <sys/tree.h>
#include <sys/module.h>
#include <sys/filio.h>
#include <sys/vnode.h>
#include <machine/intr_machdep.h>
#include <machine/xen/synch_bitops.h>
#include <xen/xen-os.h>
#include <xen/evtchn.h>
#include <xen/xen_intr.h>
#include <xen/evtchn/evtchnvar.h>
MALLOC_DEFINE(M_EVTCHN, "evtchn_dev", "Xen event channel user-space device");
struct user_evtchn;
static int evtchn_cmp(struct user_evtchn *u1, struct user_evtchn *u2);
RB_HEAD(evtchn_tree, user_evtchn);
struct per_user_data {
struct mtx bind_mutex; /* serialize bind/unbind operations */
struct evtchn_tree evtchns;
/* 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 sx ring_cons_mutex; /* protect against concurrent readers */
struct mtx ring_prod_mutex; /* product against concurrent interrupts */
struct selinfo ev_rsel;
};
struct user_evtchn {
RB_ENTRY(user_evtchn) node;
struct per_user_data *user;
evtchn_port_t port;
xen_intr_handle_t handle;
bool enabled;
};
RB_GENERATE_STATIC(evtchn_tree, user_evtchn, node, evtchn_cmp);
static device_t evtchn_dev;
static d_read_t evtchn_read;
static d_write_t evtchn_write;
static d_ioctl_t evtchn_ioctl;
static d_poll_t evtchn_poll;
static d_open_t evtchn_open;
static void evtchn_release(void *arg);
static struct cdevsw evtchn_devsw = {
.d_version = D_VERSION,
.d_open = evtchn_open,
.d_read = evtchn_read,
.d_write = evtchn_write,
.d_ioctl = evtchn_ioctl,
.d_poll = evtchn_poll,
.d_name = "evtchn",
};
/*------------------------- Red-black tree helpers ---------------------------*/
static int
evtchn_cmp(struct user_evtchn *u1, struct user_evtchn *u2)
{
return (u1->port - u2->port);
}
static struct user_evtchn *
find_evtchn(struct per_user_data *u, evtchn_port_t port)
{
struct user_evtchn tmp = {
.port = port,
};
return (RB_FIND(evtchn_tree, &u->evtchns, &tmp));
}
/*--------------------------- Interrupt handlers -----------------------------*/
static int
evtchn_filter(void *arg)
{
struct user_evtchn *evtchn;
evtchn = arg;
if (!evtchn->enabled && bootverbose) {
device_printf(evtchn_dev,
"Received upcall for disabled event channel %d\n",
evtchn->port);
}
evtchn_mask_port(evtchn->port);
evtchn->enabled = false;
return (FILTER_SCHEDULE_THREAD);
}
static void
evtchn_interrupt(void *arg)
{
struct user_evtchn *evtchn;
struct per_user_data *u;
evtchn = arg;
u = evtchn->user;
/*
* Protect against concurrent events using this handler
* on different CPUs.
*/
mtx_lock(&u->ring_prod_mutex);
if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) {
u->ring[EVTCHN_RING_MASK(u->ring_prod)] = evtchn->port;
wmb(); /* Ensure ring contents visible */
if (u->ring_cons == u->ring_prod++) {
wakeup(u);
selwakeup(&u->ev_rsel);
}
} else
u->ring_overflow = 1;
mtx_unlock(&u->ring_prod_mutex);
}
/*------------------------- Character device methods -------------------------*/
static int
evtchn_open(struct cdev *dev, int flag, int otyp, struct thread *td)
{
struct per_user_data *u;
int error;
u = malloc(sizeof(*u), M_EVTCHN, M_WAITOK | M_ZERO);
u->ring = malloc(PAGE_SIZE, M_EVTCHN, M_WAITOK | M_ZERO);
/* Initialize locks */
mtx_init(&u->bind_mutex, "evtchn_bind_mutex", NULL, MTX_DEF);
sx_init(&u->ring_cons_mutex, "evtchn_ringc_sx");
mtx_init(&u->ring_prod_mutex, "evtchn_ringp_mutex", NULL, MTX_DEF);
/* Initialize red-black tree. */
RB_INIT(&u->evtchns);
/* Assign the allocated per_user_data to this open instance. */
error = devfs_set_cdevpriv(u, evtchn_release);
if (error != 0) {
mtx_destroy(&u->bind_mutex);
mtx_destroy(&u->ring_prod_mutex);
sx_destroy(&u->ring_cons_mutex);
free(u->ring, M_EVTCHN);
free(u, M_EVTCHN);
}
return (error);
}
static void
evtchn_release(void *arg)
{
struct per_user_data *u;
struct user_evtchn *evtchn, *tmp;
u = arg;
seldrain(&u->ev_rsel);
RB_FOREACH_SAFE(evtchn, evtchn_tree, &u->evtchns, tmp) {
xen_intr_unbind(&evtchn->handle);
RB_REMOVE(evtchn_tree, &u->evtchns, evtchn);
free(evtchn, M_EVTCHN);
}
mtx_destroy(&u->bind_mutex);
mtx_destroy(&u->ring_prod_mutex);
sx_destroy(&u->ring_cons_mutex);
free(u->ring, M_EVTCHN);
free(u, M_EVTCHN);
}
static int
evtchn_read(struct cdev *dev, struct uio *uio, int ioflag)
{
int error, count;
unsigned int c, p, bytes1 = 0, bytes2 = 0;
struct per_user_data *u;
error = devfs_get_cdevpriv((void **)&u);
if (error != 0)
return (EINVAL);
/* Whole number of ports. */
count = uio->uio_resid;
count &= ~(sizeof(evtchn_port_t)-1);
if (count == 0)
return (0);
if (count > PAGE_SIZE)
count = PAGE_SIZE;
sx_xlock(&u->ring_cons_mutex);
for (;;) {
error = EFBIG;
if (u->ring_overflow)
goto unlock_out;
c = u->ring_cons;
p = u->ring_prod;
if (c != p)
break;
if (ioflag & IO_NDELAY) {
sx_xunlock(&u->ring_cons_mutex);
return (EWOULDBLOCK);
}
error = sx_sleep(u, &u->ring_cons_mutex, PCATCH, "evtchw", 0);
if ((error != 0) && (error != EWOULDBLOCK))
return (error);
}
/* 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;
}
error = EFAULT;
rmb(); /* Ensure that we see the port before we copy it. */
if (uiomove(&u->ring[EVTCHN_RING_MASK(c)], bytes1, uio) ||
((bytes2 != 0) && uiomove(&u->ring[0], bytes2, uio)))
goto unlock_out;
u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);
error = 0;
unlock_out:
sx_xunlock(&u->ring_cons_mutex);
return (error);
}
static int
evtchn_write(struct cdev *dev, struct uio *uio, int ioflag)
{
int error, i, count;
evtchn_port_t *kbuf;
struct per_user_data *u;
error = devfs_get_cdevpriv((void **)&u);
if (error != 0)
return (EINVAL);
kbuf = malloc(PAGE_SIZE, M_EVTCHN, M_WAITOK);
if (kbuf == NULL)
return (ENOMEM);
count = uio->uio_resid;
/* Whole number of ports. */
count &= ~(sizeof(evtchn_port_t)-1);
error = 0;
if (count == 0)
goto out;
if (count > PAGE_SIZE)
count = PAGE_SIZE;
error = uiomove(kbuf, count, uio);
if (error != 0)
goto out;
mtx_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;
evtchn_unmask_port(evtchn->port);
}
}
mtx_unlock(&u->bind_mutex);
error = 0;
out:
free(kbuf, M_EVTCHN);
return (error);
}
static inline int
evtchn_bind_user_port(struct per_user_data *u, struct user_evtchn *evtchn)
{
int error;
evtchn->port = xen_intr_port(evtchn->handle);
evtchn->user = u;
evtchn->enabled = true;
mtx_lock(&u->bind_mutex);
RB_INSERT(evtchn_tree, &u->evtchns, evtchn);
mtx_unlock(&u->bind_mutex);
error = xen_intr_add_handler(evtchn_dev, evtchn_filter,
evtchn_interrupt, evtchn, INTR_TYPE_MISC | INTR_MPSAFE,
evtchn->handle);
if (error != 0) {
xen_intr_unbind(&evtchn->handle);
mtx_lock(&u->bind_mutex);
RB_REMOVE(evtchn_tree, &u->evtchns, evtchn);
mtx_unlock(&u->bind_mutex);
free(evtchn, M_EVTCHN);
}
return (error);
}
static int
evtchn_ioctl(struct cdev *dev, unsigned long cmd, caddr_t arg,
int mode, struct thread *td __unused)
{
struct per_user_data *u;
int error;
error = devfs_get_cdevpriv((void **)&u);
if (error != 0)
return (EINVAL);
switch (cmd) {
case IOCTL_EVTCHN_BIND_VIRQ: {
struct ioctl_evtchn_bind_virq *bind;
struct user_evtchn *evtchn;
evtchn = malloc(sizeof(*evtchn), M_EVTCHN, M_WAITOK | M_ZERO);
bind = (struct ioctl_evtchn_bind_virq *)arg;
error = xen_intr_bind_virq(evtchn_dev, bind->virq, 0,
NULL, NULL, NULL, 0, &evtchn->handle);
if (error != 0) {
free(evtchn, M_EVTCHN);
break;
}
error = evtchn_bind_user_port(u, evtchn);
if (error != 0)
break;
bind->port = evtchn->port;
break;
}
case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
struct ioctl_evtchn_bind_interdomain *bind;
struct user_evtchn *evtchn;
evtchn = malloc(sizeof(*evtchn), M_EVTCHN, M_WAITOK | M_ZERO);
bind = (struct ioctl_evtchn_bind_interdomain *)arg;
error = xen_intr_bind_remote_port(evtchn_dev,
bind->remote_domain, bind->remote_port, NULL,
NULL, NULL, 0, &evtchn->handle);
if (error != 0) {
free(evtchn, M_EVTCHN);
break;
}
error = evtchn_bind_user_port(u, evtchn);
if (error != 0)
break;
bind->port = evtchn->port;
break;
}
case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
struct ioctl_evtchn_bind_unbound_port *bind;
struct user_evtchn *evtchn;
evtchn = malloc(sizeof(*evtchn), M_EVTCHN, M_WAITOK | M_ZERO);
bind = (struct ioctl_evtchn_bind_unbound_port *)arg;
error = xen_intr_alloc_and_bind_local_port(evtchn_dev,
bind->remote_domain, NULL, NULL, NULL, 0, &evtchn->handle);
if (error != 0) {
free(evtchn, M_EVTCHN);
break;
}
error = evtchn_bind_user_port(u, evtchn);
if (error != 0)
break;
bind->port = evtchn->port;
break;
}
case IOCTL_EVTCHN_UNBIND: {
struct ioctl_evtchn_unbind *unbind;
struct user_evtchn *evtchn;
unbind = (struct ioctl_evtchn_unbind *)arg;
mtx_lock(&u->bind_mutex);
evtchn = find_evtchn(u, unbind->port);
if (evtchn == NULL) {
error = ENOTCONN;
break;
}
xen_intr_unbind(&evtchn->handle);
RB_REMOVE(evtchn_tree, &u->evtchns, evtchn);
mtx_unlock(&u->bind_mutex);
free(evtchn, M_EVTCHN);
error = 0;
break;
}
case IOCTL_EVTCHN_NOTIFY: {
struct ioctl_evtchn_notify *notify;
struct user_evtchn *evtchn;
notify = (struct ioctl_evtchn_notify *)arg;
mtx_lock(&u->bind_mutex);
evtchn = find_evtchn(u, notify->port);
if (evtchn == NULL) {
error = ENOTCONN;
break;
}
xen_intr_signal(evtchn->handle);
mtx_unlock(&u->bind_mutex);
error = 0;
break;
}
case IOCTL_EVTCHN_RESET: {
/* Initialise the ring to empty. Clear errors. */
sx_xlock(&u->ring_cons_mutex);
mtx_lock(&u->ring_prod_mutex);
u->ring_cons = u->ring_prod = u->ring_overflow = 0;
mtx_unlock(&u->ring_prod_mutex);
sx_xunlock(&u->ring_cons_mutex);
error = 0;
break;
}
case FIONBIO:
case FIOASYNC:
/* Handled in an upper layer */
error = 0;
break;
default:
error = ENOTTY;
break;
}
return (error);
}
static int
evtchn_poll(struct cdev *dev, int events, struct thread *td)
{
struct per_user_data *u;
int error, mask;
error = devfs_get_cdevpriv((void **)&u);
if (error != 0)
return (POLLERR);
/* we can always write */
mask = events & (POLLOUT | POLLWRNORM);
mtx_lock(&u->ring_prod_mutex);
if (events & (POLLIN | POLLRDNORM)) {
if (u->ring_cons != u->ring_prod) {
mask |= events & (POLLIN | POLLRDNORM);
} else {
/* Record that someone is waiting */
selrecord(td, &u->ev_rsel);
}
}
mtx_unlock(&u->ring_prod_mutex);
return (mask);
}
/*------------------ Private Device Attachment Functions --------------------*/
static void
evtchn_identify(driver_t *driver, device_t parent)
{
KASSERT((xen_domain()),
("Trying to attach evtchn device on non Xen domain"));
evtchn_dev = BUS_ADD_CHILD(parent, 0, "evtchn", 0);
if (evtchn_dev == NULL)
panic("unable to attach evtchn user-space device");
}
static int
evtchn_probe(device_t dev)
{
device_set_desc(dev, "Xen event channel user-space device");
return (BUS_PROBE_NOWILDCARD);
}
static int
evtchn_attach(device_t dev)
{
make_dev_credf(MAKEDEV_ETERNAL, &evtchn_devsw, 0, NULL, UID_ROOT,
GID_WHEEL, 0600, "xen/evtchn");
return (0);
}
/*-------------------- Private Device Attachment Data -----------------------*/
static device_method_t evtchn_methods[] = {
DEVMETHOD(device_identify, evtchn_identify),
DEVMETHOD(device_probe, evtchn_probe),
DEVMETHOD(device_attach, evtchn_attach),
DEVMETHOD_END
};
static driver_t evtchn_driver = {
"evtchn",
evtchn_methods,
0,
};
devclass_t evtchn_devclass;
DRIVER_MODULE(evtchn, xenpv, evtchn_driver, evtchn_devclass, 0, 0);
MODULE_DEPEND(evtchn, xenpv, 1, 1, 1);