xen/io/evtchn_dev.c

	evtchn_dev.c revision 193974072f41a843678abf5f61979c748687e66b
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */


/*
 * 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 file may be 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/types.h>
#include <sys/hypervisor.h>
#include <sys/machsystm.h>
#include <sys/mutex.h>
#include <sys/evtchn_impl.h>
#include <sys/ddi_impldefs.h>
#include <sys/avintr.h>
#include <sys/cpuvar.h>
#include <sys/smp_impldefs.h>
#include <sys/archsystm.h>
#include <sys/sysmacros.h>
#include <sys/fcntl.h>
#include <sys/open.h>
#include <sys/stat.h>
#include <sys/psm.h>
#include <sys/cpu.h>
#include <sys/cmn_err.h>
#include <sys/xen_errno.h>
#include <sys/policy.h>
#include <xen/sys/evtchn.h>

/* Some handy macros */
#define EVTCHNDRV_MINOR2INST(minor) ((int)(minor))
#define EVTCHNDRV_DEFAULT_NCLONES   256
#define EVTCHNDRV_INST2SOFTS(inst)  \
    (ddi_get_soft_state(evtchndrv_statep, (inst)))

/* Soft state data structure for evtchn driver */
struct evtsoftdata {
    dev_info_t *dip;
    /* Notification ring, accessed via /dev/xen/evtchn. */
#define EVTCHN_RING_SIZE    (PAGESIZE / 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;

    /* Processes wait on this queue when ring is empty. */
    kcondvar_t evtchn_wait;
    kmutex_t evtchn_lock;
    struct pollhead evtchn_pollhead;

    /* last pid to bind to this event channel. debug aid. */
    pid_t pid;
};

static void *evtchndrv_statep;
int evtchndrv_nclones = EVTCHNDRV_DEFAULT_NCLONES;
static int *evtchndrv_clone_tab;
static dev_info_t *evtchndrv_dip;
static kmutex_t evtchndrv_clone_tab_mutex;

static int evtchndrv_detach(dev_info_t *, ddi_detach_cmd_t);

/* Who's bound to each port? */
static struct evtsoftdata *port_user[NR_EVENT_CHANNELS];
static kmutex_t port_user_lock;

void
evtchn_device_upcall()
{
    struct evtsoftdata *ep;
    int port;

    /*
     * This is quite gross, we had to leave the evtchn that led to this
     * invocation in a global mailbox, retrieve it now.
     * We do this because the interface doesn't offer us a way to pass
     * a dynamic argument up through the generic interrupt service layer.
     * The mailbox is safe since we either run with interrupts disabled or
     * non-preemptable till we reach here.
     */
    port = ec_dev_mbox;
    ASSERT(port != 0);
    ec_dev_mbox = 0;
    ec_clear_evtchn(port);
    mutex_enter(&port_user_lock);

    if ((ep = port_user[port]) != NULL) {
        mutex_enter(&ep->evtchn_lock);
        if ((ep->ring_prod - ep->ring_cons) < EVTCHN_RING_SIZE) {
            ep->ring[EVTCHN_RING_MASK(ep->ring_prod)] = port;
            /*
             * Wake up reader when ring goes non-empty
             */
            if (ep->ring_cons == ep->ring_prod++) {
                cv_signal(&ep->evtchn_wait);
                mutex_exit(&ep->evtchn_lock);
                pollwakeup(&ep->evtchn_pollhead,
                    POLLIN | POLLRDNORM);
                goto done;
            }
        } else {
            ep->ring_overflow = 1;
        }
        mutex_exit(&ep->evtchn_lock);
    }

done:
    mutex_exit(&port_user_lock);
}

/* ARGSUSED */
static int
evtchndrv_read(dev_t dev, struct uio *uio, cred_t *cr)
{
    int rc = 0;
    ssize_t count;
    unsigned int c, p, bytes1 = 0, bytes2 = 0;
    struct evtsoftdata *ep;
    minor_t minor = getminor(dev);

    if (secpolicy_xvm_control(cr))
        return (EPERM);

    ep = EVTCHNDRV_INST2SOFTS(EVTCHNDRV_MINOR2INST(minor));

    /* Whole number of ports. */
    count = uio->uio_resid;
    count &= ~(sizeof (evtchn_port_t) - 1);

    if (count == 0)
        return (0);

    if (count > PAGESIZE)
        count = PAGESIZE;

    mutex_enter(&ep->evtchn_lock);
    for (;;) {
        if (ep->ring_overflow) {
            rc = EFBIG;
            goto done;
        }

        if ((c = ep->ring_cons) != (p = ep->ring_prod))
            break;

        if (uio->uio_fmode & O_NONBLOCK) {
            rc = EAGAIN;
            goto done;
        }

        if (cv_wait_sig(&ep->evtchn_wait, &ep->evtchn_lock) == 0) {
            rc = EINTR;
            goto done;
        }
    }

    /* 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;
    }

    if (uiomove(&ep->ring[EVTCHN_RING_MASK(c)], bytes1, UIO_READ, uio) ||
        ((bytes2 != 0) && uiomove(&ep->ring[0], bytes2, UIO_READ, uio))) {
        rc = EFAULT;
        goto done;
    }

    ep->ring_cons += (bytes1 + bytes2) / sizeof (evtchn_port_t);
done:
    mutex_exit(&ep->evtchn_lock);
    return (rc);
}

/* ARGSUSED */
static int
evtchndrv_write(dev_t dev, struct uio *uio, cred_t *cr)
{
    int  rc, i;
    ssize_t count;
    evtchn_port_t *kbuf;
    struct evtsoftdata *ep;
    ulong_t flags;
    minor_t minor = getminor(dev);

    if (secpolicy_xvm_control(cr))
        return (EPERM);

    ep = EVTCHNDRV_INST2SOFTS(EVTCHNDRV_MINOR2INST(minor));

    kbuf = kmem_alloc(PAGESIZE, KM_SLEEP);

    /* Whole number of ports. */
    count = uio->uio_resid;
    count &= ~(sizeof (evtchn_port_t) - 1);

    if (count == 0) {
        rc = 0;
        goto out;
    }

    if (count > PAGESIZE)
        count = PAGESIZE;

    if ((rc = uiomove(kbuf, count, UIO_WRITE, uio)) != 0)
        goto out;

    mutex_enter(&port_user_lock);
    for (i = 0; i < (count / sizeof (evtchn_port_t)); i++)
        if ((kbuf[i] < NR_EVENT_CHANNELS) &&
            (port_user[kbuf[i]] == ep)) {
            flags = intr_clear();
            ec_unmask_evtchn(kbuf[i]);
            intr_restore(flags);
        }
    mutex_exit(&port_user_lock);

out:
    kmem_free(kbuf, PAGESIZE);
    return (rc);
}

static void
evtchn_bind_to_user(struct evtsoftdata *u, int port)
{
    ulong_t flags;

    /*
     * save away the PID of the last process to bind to this event channel.
     * Useful for debugging.
     */
    u->pid = ddi_get_pid();

    mutex_enter(&port_user_lock);
    ASSERT(port_user[port] == NULL);
    port_user[port] = u;
    ec_irq_add_evtchn(ec_dev_irq, port);
    flags = intr_clear();
    ec_unmask_evtchn(port);
    intr_restore(flags);
    mutex_exit(&port_user_lock);
}

static void
evtchndrv_close_evtchn(int port)
{
    struct evtsoftdata *ep;

    ASSERT(MUTEX_HELD(&port_user_lock));
    ep = port_user[port];
    ASSERT(ep != NULL);
    (void) ec_mask_evtchn(port);
    /*
     * It is possible the event is in transit to us.
     * If it is already in the ring buffer, then a client may
     * get a spurious event notification on the next read of
     * of the evtchn device.  Clients will need to be able to
     * handle getting a spurious event notification.
     */
    port_user[port] = NULL;
    /*
     * The event is masked and should stay so, clean it up.
     */
    ec_irq_rm_evtchn(ec_dev_irq, port);
}

/* ARGSUSED */
static int
evtchndrv_ioctl(dev_t dev, int cmd, intptr_t data, int flag, cred_t *cr,
    int *rvalp)
{
    int err = 0;
    struct evtsoftdata *ep;
    minor_t minor = getminor(dev);

    if (secpolicy_xvm_control(cr))
        return (EPERM);

    ep = EVTCHNDRV_INST2SOFTS(EVTCHNDRV_MINOR2INST(minor));

    *rvalp = 0;

    switch (cmd) {
    case IOCTL_EVTCHN_BIND_VIRQ: {
        struct ioctl_evtchn_bind_virq bind;

        if (copyin((void *)data, &bind, sizeof (bind))) {
            err = EFAULT;
            break;
        }

        if ((err = xen_bind_virq(bind.virq, 0, rvalp)) != 0)
            break;

        evtchn_bind_to_user(ep, *rvalp);
        break;
    }

    case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
        struct ioctl_evtchn_bind_interdomain bind;

        if (copyin((void *)data, &bind, sizeof (bind))) {
            err = EFAULT;
            break;
        }

        if ((err = xen_bind_interdomain(bind.remote_domain,
            bind.remote_port, rvalp)) != 0)
            break;

        ec_bind_vcpu(*rvalp, 0);
        evtchn_bind_to_user(ep, *rvalp);
        break;
    }

    case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
        struct ioctl_evtchn_bind_unbound_port bind;

        if (copyin((void *)data, &bind, sizeof (bind))) {
            err = EFAULT;
            break;
        }

        if ((err = xen_alloc_unbound_evtchn(bind.remote_domain,
            rvalp)) != 0)
            break;

        evtchn_bind_to_user(ep, *rvalp);
        break;
    }

    case IOCTL_EVTCHN_UNBIND: {
        struct ioctl_evtchn_unbind unbind;

        if (copyin((void *)data, &unbind, sizeof (unbind))) {
            err = EFAULT;
            break;
        }

        if (unbind.port >= NR_EVENT_CHANNELS) {
            err = EFAULT;
            break;
        }

        mutex_enter(&port_user_lock);

        if (port_user[unbind.port] != ep) {
            mutex_exit(&port_user_lock);
            err = ENOTCONN;
            break;
        }

        evtchndrv_close_evtchn(unbind.port);
        mutex_exit(&port_user_lock);
        break;
    }

    case IOCTL_EVTCHN_NOTIFY: {
        struct ioctl_evtchn_notify notify;

        if (copyin((void *)data, &notify, sizeof (notify))) {
            err = EFAULT;
            break;
        }

        if (notify.port >= NR_EVENT_CHANNELS) {
            err = EINVAL;
        } else if (port_user[notify.port] != ep) {
            err = ENOTCONN;
        } else {
            ec_notify_via_evtchn(notify.port);
        }
        break;
    }

    default:
        err = ENOSYS;
    }

    return (err);
}

static int
evtchndrv_poll(dev_t dev, short ev, int anyyet, short *revp, pollhead_t **phpp)
{
    struct evtsoftdata *ep;
    minor_t minor = getminor(dev);
    short mask = 0;

    ep = EVTCHNDRV_INST2SOFTS(EVTCHNDRV_MINOR2INST(minor));
    *phpp = (struct pollhead *)NULL;

    if (ev & POLLOUT)
        mask |= POLLOUT;
    if (ep->ring_overflow)
        mask |= POLLERR;
    if (ev & (POLLIN | POLLRDNORM)) {
        mutex_enter(&ep->evtchn_lock);
        if (ep->ring_cons != ep->ring_prod)
            mask |= (POLLIN | POLLRDNORM) & ev;
        else
            if (mask == 0 && !anyyet)
                *phpp = &ep->evtchn_pollhead;
        mutex_exit(&ep->evtchn_lock);
    }
    *revp = mask;
    return (0);
}


/* ARGSUSED */
static int
evtchndrv_open(dev_t *devp, int flag, int otyp, cred_t *credp)
{
    struct evtsoftdata *ep;
    minor_t minor = getminor(*devp);

    if (otyp == OTYP_BLK)
        return (ENXIO);

    /*
     * only allow open on minor = 0 - the clone device
     */
    if (minor != 0)
        return (ENXIO);

    /*
     * find a free slot and grab it
     */
    mutex_enter(&evtchndrv_clone_tab_mutex);
    for (minor = 1; minor < evtchndrv_nclones; minor++) {
        if (evtchndrv_clone_tab[minor] == 0) {
            evtchndrv_clone_tab[minor] = 1;
            break;
        }
    }
    mutex_exit(&evtchndrv_clone_tab_mutex);
    if (minor == evtchndrv_nclones)
        return (EAGAIN);

    /* Allocate softstate structure */
    if (ddi_soft_state_zalloc(evtchndrv_statep,
        EVTCHNDRV_MINOR2INST(minor)) != DDI_SUCCESS) {
        mutex_enter(&evtchndrv_clone_tab_mutex);
        evtchndrv_clone_tab[minor] = 0;
        mutex_exit(&evtchndrv_clone_tab_mutex);
        return (EAGAIN);
    }
    ep = EVTCHNDRV_INST2SOFTS(EVTCHNDRV_MINOR2INST(minor));

    /* ... and init it */
    ep->dip = evtchndrv_dip;

    cv_init(&ep->evtchn_wait, NULL, CV_DEFAULT, NULL);
    mutex_init(&ep->evtchn_lock, NULL, MUTEX_DEFAULT, NULL);

    ep->ring = kmem_alloc(PAGESIZE, KM_SLEEP);

    /* clone driver */
    *devp = makedevice(getmajor(*devp), minor);

    return (0);
}

/* ARGSUSED */
static int
evtchndrv_close(dev_t dev, int flag, int otyp, struct cred *credp)
{
    struct evtsoftdata *ep;
    minor_t minor = getminor(dev);
    int i;

    ep = EVTCHNDRV_INST2SOFTS(EVTCHNDRV_MINOR2INST(minor));
    if (ep == NULL)
        return (ENXIO);

    mutex_enter(&port_user_lock);


    for (i = 0; i < NR_EVENT_CHANNELS; i++) {
        if (port_user[i] != ep)
            continue;

        evtchndrv_close_evtchn(i);
    }

    mutex_exit(&port_user_lock);

    kmem_free(ep->ring, PAGESIZE);
    ddi_soft_state_free(evtchndrv_statep, EVTCHNDRV_MINOR2INST(minor));

    /*
     * free clone tab slot
     */
    mutex_enter(&evtchndrv_clone_tab_mutex);
    evtchndrv_clone_tab[minor] = 0;
    mutex_exit(&evtchndrv_clone_tab_mutex);

    return (0);
}

/* ARGSUSED */
static int
evtchndrv_info(dev_info_t *dip, ddi_info_cmd_t cmd, void *arg, void **result)
{
    dev_t   dev = (dev_t)arg;
    minor_t minor = getminor(dev);
    int retval;

    switch (cmd) {
    case DDI_INFO_DEVT2DEVINFO:
        if (minor != 0 || evtchndrv_dip == NULL) {
            *result = (void *)NULL;
            retval = DDI_FAILURE;
        } else {
            *result = (void *)evtchndrv_dip;
            retval = DDI_SUCCESS;
        }
        break;
    case DDI_INFO_DEVT2INSTANCE:
        *result = (void *)0;
        retval = DDI_SUCCESS;
        break;
    default:
        retval = DDI_FAILURE;
    }
    return (retval);
}


static int
evtchndrv_attach(dev_info_t *dip, ddi_attach_cmd_t cmd)
{
    int error;
    int unit = ddi_get_instance(dip);


    switch (cmd) {
    case DDI_ATTACH:
        break;
    case DDI_RESUME:
        return (DDI_SUCCESS);
    default:
        cmn_err(CE_WARN, "evtchn_attach: unknown cmd 0x%x\n", cmd);
        return (DDI_FAILURE);
    }

    /* DDI_ATTACH */

    /*
     * only one instance - but we clone using the open routine
     */
    if (ddi_get_instance(dip) > 0)
        return (DDI_FAILURE);

    mutex_init(&evtchndrv_clone_tab_mutex, NULL, MUTEX_DRIVER,
        NULL);

    error = ddi_create_minor_node(dip, "evtchn", S_IFCHR, unit,
        DDI_PSEUDO, NULL);
    if (error != DDI_SUCCESS)
        goto fail;

    /*
     * save dip for getinfo
     */
    evtchndrv_dip = dip;
    ddi_report_dev(dip);

    mutex_init(&port_user_lock, NULL, MUTEX_DRIVER, NULL);
    (void) memset(port_user, 0, sizeof (port_user));

    ec_dev_irq = ec_dev_alloc_irq();
    (void) add_avintr(NULL, IPL_EVTCHN, (avfunc)evtchn_device_upcall,
        "evtchn_driver", ec_dev_irq, NULL, NULL, NULL, dip);

    return (DDI_SUCCESS);

fail:
    (void) evtchndrv_detach(dip, DDI_DETACH);
    return (error);
}

/*ARGSUSED*/
static int
evtchndrv_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
{
    /*
     * Don't allow detach for now.
     */
    return (DDI_FAILURE);
}

/* Solaris driver framework */

static  struct cb_ops evtchndrv_cb_ops = {
    evtchndrv_open,     /* cb_open */
    evtchndrv_close,    /* cb_close */
    nodev,          /* cb_strategy */
    nodev,          /* cb_print */
    nodev,          /* cb_dump */
    evtchndrv_read,     /* cb_read */
    evtchndrv_write,    /* cb_write */
    evtchndrv_ioctl,    /* cb_ioctl */
    nodev,          /* cb_devmap */
    nodev,          /* cb_mmap */
    nodev,          /* cb_segmap */
    evtchndrv_poll,     /* cb_chpoll */
    ddi_prop_op,        /* cb_prop_op */
    0,          /* cb_stream */
    D_NEW | D_MP | D_64BIT  /* cb_flag */
};

static struct dev_ops evtchndrv_dev_ops = {
    DEVO_REV,       /* devo_rev */
    0,          /* devo_refcnt */
    evtchndrv_info,     /* devo_getinfo */
    nulldev,        /* devo_identify */
    nulldev,        /* devo_probe */
    evtchndrv_attach,   /* devo_attach */
    evtchndrv_detach,   /* devo_detach */
    nodev,          /* devo_reset */
    &evtchndrv_cb_ops,  /* devo_cb_ops */
    NULL,           /* devo_bus_ops */
    NULL,           /* power */
    ddi_quiesce_not_needed,     /* devo_quiesce */
};

static struct modldrv modldrv = {
    &mod_driverops,     /* Type of module.  This one is a driver */
    "Evtchn driver",    /* Name of the module. */
    &evtchndrv_dev_ops  /* driver ops */
};

static struct modlinkage modlinkage = {
    MODREV_1,
    &modldrv,
    NULL
};

int
_init(void)
{
    int err;

    err = ddi_soft_state_init(&evtchndrv_statep,
        sizeof (struct evtsoftdata), 1);
    if (err)
        return (err);

    err = mod_install(&modlinkage);
    if (err)
        ddi_soft_state_fini(&evtchndrv_statep);
    else
        evtchndrv_clone_tab = kmem_zalloc(
            sizeof (int) * evtchndrv_nclones, KM_SLEEP);
    return (err);
}

int
_fini(void)
{
    int e;

    e = mod_remove(&modlinkage);
    if (e)
        return (e);

    ddi_soft_state_fini(&evtchndrv_statep);

    return (0);
}

int
_info(struct modinfo *modinfop)
{
    return (mod_info(&modlinkage, modinfop));
}