/*
 * 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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 * Copyright 2017 Joyent, Inc.
 */


/*
 * 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;

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

        pid_t pid;              /* last pid to bind to this event channel. */
        processorid_t cpu;      /* cpu thread/evtchn is bound to */
};

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;

uint_t
evtchn_device_upcall(caddr_t arg __unused, caddr_t arg1 __unused)
{
        struct evtsoftdata *ep;
        int port;

        /*
         * This is quite gross, we had to leave the evtchn that led to this
         * invocation in a per-cpu 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 = CPU->cpu_m.mcpu_ec_mbox;
        ASSERT(port != 0);
        CPU->cpu_m.mcpu_ec_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);
        return (DDI_INTR_CLAIMED);
}

/* 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);
        evtchn_port_t sbuf[32];

        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;

        if (count <= sizeof (sbuf))
                kbuf = sbuf;
        else
                kbuf = kmem_alloc(PAGESIZE, KM_SLEEP);
        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:
        if (kbuf != sbuf)
                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));

        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;
                }
                mutex_exit(&ep->evtchn_lock);
        }
        if ((mask == 0 && !anyyet) || (ev & POLLET)) {
                *phpp = &ep->evtchn_pollhead;
        }
        *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);
        pollhead_clean(&ep->evtchn_pollhead);
        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, 0);
        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));
}