xen/io/xenbus_dev.c

/*
 * 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.
 */

/*
 * xenbus_dev.c
 *
 * Driver giving user-space access to the kernel's xenbus connection
 * to xenstore.
 *
 * Copyright (c) 2005, Christian Limpach
 * Copyright (c) 2005, Rusty Russell, IBM Corporation
 *
 * 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/sysmacros.h>
#include <sys/conf.h>
#include <sys/stat.h>
#include <sys/modctl.h>
#include <sys/uio.h>
#include <sys/list.h>
#include <sys/file.h>
#include <sys/errno.h>
#include <sys/open.h>
#include <sys/cred.h>
#include <sys/condvar.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/policy.h>

#ifdef XPV_HVM_DRIVER
#include <public/io/xenbus.h>
#include <public/io/xs_wire.h>
#include <sys/xpv_support.h>
#endif
#include <sys/hypervisor.h>
#include <xen/sys/xenbus.h>
#include <xen/sys/xenbus_comms.h>
#include <xen/sys/xenbus_impl.h>
#include <xen/public/io/xs_wire.h>

#ifdef DEBUG
#define XENBUSDRV_DBPRINT(fmt) { if (xenbusdrv_debug) cmn_err fmt; }
#else
#define XENBUSDRV_DBPRINT(fmt)
#endif /* ifdef DEBUG */

/* Some handy macros */
#define XENBUSDRV_MASK_READ_IDX(idx)    ((idx) & (PAGESIZE - 1))
#define XENBUSDRV_MINOR2INST(minor) ((int)(minor))
#define XENBUSDRV_NCLONES       256
#define XENBUSDRV_INST2SOFTS(instance)  \
    ((xenbus_dev_t *)ddi_get_soft_state(xenbusdrv_statep, (instance)))

static int xenbusdrv_debug = 0;
static int xenbusdrv_clone_tab[XENBUSDRV_NCLONES];
static dev_info_t *xenbusdrv_dip;
static kmutex_t xenbusdrv_clone_tab_mutex;

struct xenbus_dev_transaction {
    list_t list;
    xenbus_transaction_t handle;
};

/* Soft state data structure for xenbus driver */
struct xenbus_dev_data {
    dev_info_t *dip;

    /* In-progress transaction. */
    list_t transactions;

    /* Partial request. */
    unsigned int len;
    union {
        struct xsd_sockmsg msg;
        char buffer[MMU_PAGESIZE];
    } u;

    /* Response queue. */
    char read_buffer[MMU_PAGESIZE];
    unsigned int read_cons, read_prod;
    kcondvar_t read_cv;
    kmutex_t read_mutex;
    int xenstore_inst;
};
typedef struct xenbus_dev_data xenbus_dev_t;
static void *xenbusdrv_statep;

static int xenbusdrv_info(dev_info_t *, ddi_info_cmd_t, void *, void **);
static int xenbusdrv_attach(dev_info_t *, ddi_attach_cmd_t);
static int xenbusdrv_detach(dev_info_t *, ddi_detach_cmd_t);
static int xenbusdrv_open(dev_t *, int, int, cred_t *);
static int xenbusdrv_close(dev_t, int, int, cred_t *);
static int xenbusdrv_read(dev_t, struct uio *, cred_t *);
static int xenbusdrv_write(dev_t, struct uio *, cred_t *);
static int xenbusdrv_devmap(dev_t, devmap_cookie_t, offset_t, size_t, size_t *,
    uint_t);
static int xenbusdrv_segmap(dev_t, off_t, ddi_as_handle_t, caddr_t *, off_t,
    uint_t, uint_t, uint_t, cred_t *);
static int xenbusdrv_ioctl(dev_t, int, intptr_t, int, cred_t *, int *);
static int xenbusdrv_queue_reply(xenbus_dev_t *, const struct xsd_sockmsg *,
    const char *);

/* Solaris driver framework */

static  struct cb_ops xenbusdrv_cb_ops = {
    xenbusdrv_open,         /* cb_open */
    xenbusdrv_close,        /* cb_close */
    nodev,              /* cb_strategy */
    nodev,              /* cb_print */
    nodev,              /* cb_dump */
    xenbusdrv_read,         /* cb_read */
    xenbusdrv_write,        /* cb_write */
    xenbusdrv_ioctl,        /* cb_ioctl */
    xenbusdrv_devmap,       /* cb_devmap */
    NULL,               /* cb_mmap */
    xenbusdrv_segmap,       /* cb_segmap */
    nochpoll,           /* cb_chpoll */
    ddi_prop_op,            /* cb_prop_op */
    0,              /* cb_stream */
    D_DEVMAP | D_NEW | D_MP,    /* cb_flag */
    CB_REV
};

static struct dev_ops xenbusdrv_dev_ops = {
    DEVO_REV,       /* devo_rev */
    0,          /* devo_refcnt */
    xenbusdrv_info,     /* devo_getinfo */
    nulldev,        /* devo_identify */
    nulldev,        /* devo_probe */
    xenbusdrv_attach,   /* devo_attach */
    xenbusdrv_detach,   /* devo_detach */
    nodev,          /* devo_reset */
    &xenbusdrv_cb_ops,  /* devo_cb_ops */
    NULL,           /* devo_bus_ops */
    NULL,           /* devo_power */
    ddi_quiesce_not_needed,     /* devo_quiesce */
};

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

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

int
_init(void)
{
    int e;

    e = ddi_soft_state_init(&xenbusdrv_statep, sizeof (xenbus_dev_t), 1);
    if (e)
        return (e);

    e = mod_install(&modlinkage);
    if (e)
        ddi_soft_state_fini(&xenbusdrv_statep);

    return (e);
}

int
_fini(void)
{
    int e;

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

    ddi_soft_state_fini(&xenbusdrv_statep);

    return (0);
}

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

/* ARGSUSED */
static int
xenbusdrv_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 || xenbusdrv_dip == NULL) {
            *result = (void *)NULL;
            retval = DDI_FAILURE;
        } else {
            *result = (void *)xenbusdrv_dip;
            retval = DDI_SUCCESS;
        }
        break;
    case DDI_INFO_DEVT2INSTANCE:
        *result = (void *)0;
        retval = DDI_SUCCESS;
        break;
    default:
        retval = DDI_FAILURE;
    }
    return (retval);
}

static int
xenbusdrv_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, "xenbus_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(&xenbusdrv_clone_tab_mutex, NULL, MUTEX_DRIVER,
        NULL);

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

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

#ifndef XPV_HVM_DRIVER
    if (DOMAIN_IS_INITDOMAIN(xen_info))
        xs_dom0_init();
#endif

    return (DDI_SUCCESS);

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

static int
xenbusdrv_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
{
    /*
     * again, only one instance
     */
    if (ddi_get_instance(dip) > 0)
        return (DDI_FAILURE);

    switch (cmd) {
    case DDI_DETACH:
        ddi_remove_minor_node(dip, NULL);
        mutex_destroy(&xenbusdrv_clone_tab_mutex);
        xenbusdrv_dip = NULL;
        return (DDI_SUCCESS);
    case DDI_SUSPEND:
        return (DDI_SUCCESS);
    default:
        cmn_err(CE_WARN, "xenbus_detach: unknown cmd 0x%x\n", cmd);
        return (DDI_FAILURE);
    }
}

/* ARGSUSED */
static int
xenbusdrv_open(dev_t *devp, int flag, int otyp, cred_t *cr)
{
    xenbus_dev_t *xbs;
    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(&xenbusdrv_clone_tab_mutex);
    for (minor = 1; minor < XENBUSDRV_NCLONES; minor++) {
        if (xenbusdrv_clone_tab[minor] == 0) {
            xenbusdrv_clone_tab[minor] = 1;
            break;
        }
    }
    mutex_exit(&xenbusdrv_clone_tab_mutex);
    if (minor == XENBUSDRV_NCLONES)
        return (EAGAIN);

    /* Allocate softstate structure */
    if (ddi_soft_state_zalloc(xenbusdrv_statep,
        XENBUSDRV_MINOR2INST(minor)) != DDI_SUCCESS) {
        mutex_enter(&xenbusdrv_clone_tab_mutex);
        xenbusdrv_clone_tab[minor] = 0;
        mutex_exit(&xenbusdrv_clone_tab_mutex);
        return (EAGAIN);
    }
    xbs = XENBUSDRV_INST2SOFTS(XENBUSDRV_MINOR2INST(minor));

    /* ... and init it */
    xbs->dip = xenbusdrv_dip;
    mutex_init(&xbs->read_mutex, NULL, MUTEX_DRIVER, NULL);
    cv_init(&xbs->read_cv, NULL, CV_DEFAULT, NULL);
    list_create(&xbs->transactions, sizeof (struct xenbus_dev_transaction),
        offsetof(struct xenbus_dev_transaction, list));

    /* clone driver */
    *devp = makedevice(getmajor(*devp), minor);
    XENBUSDRV_DBPRINT((CE_NOTE, "Xenbus drv open succeeded, minor=%d",
        minor));

    return (0);
}

/* ARGSUSED */
static int
xenbusdrv_close(dev_t dev, int flag, int otyp, struct cred *cr)
{
    xenbus_dev_t *xbs;
    minor_t minor = getminor(dev);
    struct xenbus_dev_transaction *trans;

    xbs = XENBUSDRV_INST2SOFTS(XENBUSDRV_MINOR2INST(minor));
    if (xbs == NULL)
        return (ENXIO);

#ifdef notyet
    /*
     * XXPV - would like to be able to notify xenstore down here, but
     * as the daemon is currently written, it doesn't leave the device
     * open after initial setup, so we have no way of knowing if it has
     * gone away.
     */
    if (xbs->xenstore_inst)
        xs_notify_xenstore_down();
#endif
    /* free pending transaction */
    while (trans = (struct xenbus_dev_transaction *)
        list_head(&xbs->transactions)) {
        (void) xenbus_transaction_end(trans->handle, 1);
        list_remove(&xbs->transactions, (void *)trans);
        kmem_free(trans, sizeof (*trans));
    }

    mutex_destroy(&xbs->read_mutex);
    cv_destroy(&xbs->read_cv);
    ddi_soft_state_free(xenbusdrv_statep, XENBUSDRV_MINOR2INST(minor));

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

    XENBUSDRV_DBPRINT((CE_NOTE, "Xenbus drv close succeeded, minor=%d",
        minor));

    return (0);
}

/* ARGSUSED */
static int
xenbusdrv_read(dev_t dev, struct uio *uiop, cred_t *cr)
{
    xenbus_dev_t *xbs;
    size_t len;
    int res, ret;
    int idx;

    XENBUSDRV_DBPRINT((CE_NOTE, "xenbusdrv_read called"));

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

    xbs = XENBUSDRV_INST2SOFTS(XENBUSDRV_MINOR2INST(getminor(dev)));

    mutex_enter(&xbs->read_mutex);

    /* check if we have something to read */
    while (xbs->read_prod == xbs->read_cons) {
        if (cv_wait_sig(&xbs->read_cv, &xbs->read_mutex) == 0) {
            mutex_exit(&xbs->read_mutex);
            return (EINTR);
        }
    }

    idx = XENBUSDRV_MASK_READ_IDX(xbs->read_cons);
    res = uiop->uio_resid;

    len = xbs->read_prod - xbs->read_cons;

    if (len > (sizeof (xbs->read_buffer) - idx))
        len = sizeof (xbs->read_buffer) - idx;
    if (len > res)
        len = res;

    ret = uiomove(xbs->read_buffer + idx, len, UIO_READ, uiop);
    xbs->read_cons += res - uiop->uio_resid;
    mutex_exit(&xbs->read_mutex);

    return (ret);
}

/*
 * prepare data for xenbusdrv_read()
 */
static int
xenbusdrv_queue_reply(xenbus_dev_t *xbs, const struct xsd_sockmsg *msg,
    const char *reply)
{
    int i;
    int remaining;

    XENBUSDRV_DBPRINT((CE_NOTE, "xenbusdrv_queue_reply called"));

    mutex_enter(&xbs->read_mutex);

    remaining = sizeof (xbs->read_buffer) -
        (xbs->read_prod - xbs->read_cons);

    if (sizeof (*msg) + msg->len > remaining) {
        mutex_exit(&xbs->read_mutex);
        return (EOVERFLOW);
    }

    for (i = 0; i < sizeof (*msg); i++, xbs->read_prod++) {
        xbs->read_buffer[XENBUSDRV_MASK_READ_IDX(xbs->read_prod)] =
            ((char *)msg)[i];
    }

    for (i = 0; i < msg->len; i++, xbs->read_prod++) {
        xbs->read_buffer[XENBUSDRV_MASK_READ_IDX(xbs->read_prod)] =
            reply[i];
    }

    cv_broadcast(&xbs->read_cv);

    mutex_exit(&xbs->read_mutex);

    XENBUSDRV_DBPRINT((CE_NOTE, "xenbusdrv_queue_reply exited"));

    return (0);
}

/* ARGSUSED */
static int
xenbusdrv_write(dev_t dev, struct uio *uiop, cred_t *cr)
{
    xenbus_dev_t *xbs;
    struct xenbus_dev_transaction *trans;
    void *reply;
    size_t len;
    int rc = 0;

    XENBUSDRV_DBPRINT((CE_NOTE, "xenbusdrv_write called"));

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

    xbs = XENBUSDRV_INST2SOFTS(XENBUSDRV_MINOR2INST(getminor(dev)));
    len = uiop->uio_resid;

    if ((len + xbs->len) > sizeof (xbs->u.buffer)) {
        XENBUSDRV_DBPRINT((CE_WARN, "Request is too big"));
        rc = EINVAL;
        goto out;
    }

    if (uiomove(xbs->u.buffer + xbs->len, len, UIO_WRITE, uiop) != 0) {
        XENBUSDRV_DBPRINT((CE_WARN, "Uiomove failed"));
        rc = EFAULT;
        goto out;
    }

    xbs->len += len;

    if (xbs->len < (sizeof (xbs->u.msg)) ||
        xbs->len < (sizeof (xbs->u.msg) + xbs->u.msg.len)) {
        XENBUSDRV_DBPRINT((CE_NOTE, "Partial request"));
        return (0);
    }

    switch (xbs->u.msg.type) {
    case XS_TRANSACTION_START:
    case XS_TRANSACTION_END:
    case XS_DIRECTORY:
    case XS_READ:
    case XS_GET_PERMS:
    case XS_RELEASE:
    case XS_GET_DOMAIN_PATH:
    case XS_WRITE:
    case XS_MKDIR:
    case XS_RM:
    case XS_SET_PERMS:
        /* send the request to xenstore and get feedback */
        rc = xenbus_dev_request_and_reply(&xbs->u.msg, &reply);
        if (rc) {
            XENBUSDRV_DBPRINT((CE_WARN,
                "xenbus_dev_request_and_reply failed"));
            goto out;
        }

        /* handle transaction start/end */
        if (xbs->u.msg.type == XS_TRANSACTION_START) {
            trans = kmem_alloc(sizeof (*trans), KM_SLEEP);
            (void) ddi_strtoul((char *)reply, NULL, 0,
                (unsigned long *)&trans->handle);
            list_insert_tail(&xbs->transactions, (void *)trans);
        } else if (xbs->u.msg.type == XS_TRANSACTION_END) {
            /* try to find out the ending transaction */
            for (trans = (struct xenbus_dev_transaction *)
                list_head(&xbs->transactions); trans;
                trans = (struct xenbus_dev_transaction *)
                list_next(&xbs->transactions, (void *)trans))
                if (trans->handle ==
                    (xenbus_transaction_t)
                    xbs->u.msg.tx_id)
                    break;
            ASSERT(trans);
            /* free it, if we find it */
            list_remove(&xbs->transactions, (void *)trans);
            kmem_free(trans, sizeof (*trans));
        }

        /* prepare data for xenbusdrv_read() to get */
        rc = xenbusdrv_queue_reply(xbs, &xbs->u.msg, reply);

        kmem_free(reply, xbs->u.msg.len + 1);
        break;
    default:
        rc = EINVAL;
    }

out:
    xbs->len = 0;
    return (rc);
}

/*ARGSUSED*/
static int
xenbusdrv_devmap(dev_t dev, devmap_cookie_t dhp, offset_t off, size_t len,
    size_t *maplen, uint_t model)
{
    xenbus_dev_t *xbs;
    int err;

    xbs = XENBUSDRV_INST2SOFTS(XENBUSDRV_MINOR2INST(getminor(dev)));

    if (off != 0 || len != PAGESIZE)
        return (-1);

    if (!DOMAIN_IS_INITDOMAIN(xen_info))
        return (-1);

    err = devmap_umem_setup(dhp, xbs->dip, NULL, xb_xenstore_cookie(),
        0, PAGESIZE, PROT_READ | PROT_WRITE | PROT_USER, 0, NULL);

    if (err)
        return (err);

    *maplen = PAGESIZE;

    return (0);
}

static int
xenbusdrv_segmap(dev_t dev, off_t off, ddi_as_handle_t as, caddr_t *addrp,
    off_t len, uint_t prot, uint_t maxprot, uint_t flags, cred_t *cr)
{

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

    return (ddi_devmap_segmap(dev, off, as, addrp, len, prot,
        maxprot, flags, cr));
}

/*ARGSUSED*/
static int
xenbusdrv_ioctl(dev_t dev, int cmd, intptr_t arg, int mode, cred_t *cr,
    int *rvalp)
{
    xenbus_dev_t *xbs;

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

    xbs = XENBUSDRV_INST2SOFTS(XENBUSDRV_MINOR2INST(getminor(dev)));
    switch (cmd) {
    case IOCTL_XENBUS_XENSTORE_EVTCHN:
        *rvalp = xen_info->store_evtchn;
        break;
    case IOCTL_XENBUS_NOTIFY_UP:
        xs_notify_xenstore_up();
        xbs->xenstore_inst = 1;
        break;
    default:
        return (EINVAL);
    }

    return (0);
}