hvc_xen.c

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/*
 * xen console driver interface to hvc_console.c
 *
 * (c) 2007 Gerd Hoffmann <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/console.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/irq.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/list.h>

#include <asm/io.h>
#include <asm/xen/hypervisor.h>

#include <xen/xen.h>
#include <xen/interface/xen.h>
#include <xen/hvm.h>
#include <xen/grant_table.h>
#include <xen/page.h>
#include <xen/events.h>
#include <xen/interface/io/console.h>
#include <xen/interface/sched.h>
#include <xen/hvc-console.h>
#include <xen/xenbus.h>

#include "hvc_console.h"

#define HVC_COOKIE   0x58656e /* "Xen" in hex */

struct xencons_info {
    struct list_head list;
    struct xenbus_device *xbdev;
    struct xencons_interface *intf;
    unsigned int evtchn;
    struct hvc_struct *hvc;
    int irq;
    int vtermno;
    grant_ref_t gntref;
};

static LIST_HEAD(xenconsoles);
static DEFINE_SPINLOCK(xencons_lock);

/* ------------------------------------------------------------------ */

static struct xencons_info *vtermno_to_xencons(int vtermno)
{
    struct xencons_info *entry, *n, *ret = NULL;

    if (list_empty(&xenconsoles))
            return NULL;

    list_for_each_entry_safe(entry, n, &xenconsoles, list) {
        if (entry->vtermno == vtermno) {
            ret  = entry;
            break;
        }
    }

    return ret;
}

static inline int xenbus_devid_to_vtermno(int devid)
{
    return devid + HVC_COOKIE;
}

static inline void notify_daemon(struct xencons_info *cons)
{
    /* Use evtchn: this is called early, before irq is set up. */
    notify_remote_via_evtchn(cons->evtchn);
}

static int __write_console(struct xencons_info *xencons,
        const char *data, int len)
{
    XENCONS_RING_IDX cons, prod;
    struct xencons_interface *intf = xencons->intf;
    int sent = 0;

    cons = intf->out_cons;
    prod = intf->out_prod;
    mb();           /* update queue values before going on */
    BUG_ON((prod - cons) > sizeof(intf->out));

    while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
        intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];

    wmb();          /* write ring before updating pointer */
    intf->out_prod = prod;

    if (sent)
        notify_daemon(xencons);
    return sent;
}

static int domU_write_console(uint32_t vtermno, const char *data, int len)
{
    int ret = len;
    struct xencons_info *cons = vtermno_to_xencons(vtermno);
    if (cons == NULL)
        return -EINVAL;

    /*
     * Make sure the whole buffer is emitted, polling if
     * necessary.  We don't ever want to rely on the hvc daemon
     * because the most interesting console output is when the
     * kernel is crippled.
     */
    while (len) {
        int sent = __write_console(cons, data, len);
        
        data += sent;
        len -= sent;

        if (unlikely(len))
            HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
    }

    return ret;
}

static int domU_read_console(uint32_t vtermno, char *buf, int len)
{
    struct xencons_interface *intf;
    XENCONS_RING_IDX cons, prod;
    int recv = 0;
    struct xencons_info *xencons = vtermno_to_xencons(vtermno);
    if (xencons == NULL)
        return -EINVAL;
    intf = xencons->intf;

    cons = intf->in_cons;
    prod = intf->in_prod;
    mb();           /* get pointers before reading ring */
    BUG_ON((prod - cons) > sizeof(intf->in));

    while (cons != prod && recv < len)
        buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];

    mb();           /* read ring before consuming */
    intf->in_cons = cons;

    notify_daemon(xencons);
    return recv;
}

static struct hv_ops domU_hvc_ops = {
    .get_chars = domU_read_console,
    .put_chars = domU_write_console,
    .notifier_add = notifier_add_irq,
    .notifier_del = notifier_del_irq,
    .notifier_hangup = notifier_hangup_irq,
};

static int dom0_read_console(uint32_t vtermno, char *buf, int len)
{
    return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
}

/*
 * Either for a dom0 to write to the system console, or a domU with a
 * debug version of Xen
 */
static int dom0_write_console(uint32_t vtermno, const char *str, int len)
{
    int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
    if (rc < 0)
        return 0;

    return len;
}

static struct hv_ops dom0_hvc_ops = {
    .get_chars = dom0_read_console,
    .put_chars = dom0_write_console,
    .notifier_add = notifier_add_irq,
    .notifier_del = notifier_del_irq,
    .notifier_hangup = notifier_hangup_irq,
};

static int xen_hvm_console_init(void)
{
    int r;
    uint64_t v = 0;
    unsigned long mfn;
    struct xencons_info *info;

    if (!xen_hvm_domain())
        return -ENODEV;

    info = vtermno_to_xencons(HVC_COOKIE);
    if (!info) {
        info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
        if (!info)
            return -ENOMEM;
    } else if (info->intf != NULL) {
        /* already configured */
        return 0;
    }
    /*
     * If the toolstack (or the hypervisor) hasn't set these values, the
     * default value is 0. Even though mfn = 0 and evtchn = 0 are
     * theoretically correct values, in practice they never are and they
     * mean that a legacy toolstack hasn't initialized the pv console correctly.
     */
    r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
    if (r < 0 || v == 0)
        goto err;
    info->evtchn = v;
    v = 0;
    r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
    if (r < 0 || v == 0)
        goto err;
    mfn = v;
    info->intf = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE);
    if (info->intf == NULL)
        goto err;
    info->vtermno = HVC_COOKIE;

    spin_lock(&xencons_lock);
    list_add_tail(&info->list, &xenconsoles);
    spin_unlock(&xencons_lock);

    return 0;
err:
    kfree(info);
    return -ENODEV;
}

static int xen_pv_console_init(void)
{
    struct xencons_info *info;

    if (!xen_pv_domain())
        return -ENODEV;

    if (!xen_start_info->console.domU.evtchn)
        return -ENODEV;

    info = vtermno_to_xencons(HVC_COOKIE);
    if (!info) {
        info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
        if (!info)
            return -ENOMEM;
    } else if (info->intf != NULL) {
        /* already configured */
        return 0;
    }
    info->evtchn = xen_start_info->console.domU.evtchn;
    info->intf = mfn_to_virt(xen_start_info->console.domU.mfn);
    info->vtermno = HVC_COOKIE;

    spin_lock(&xencons_lock);
    list_add_tail(&info->list, &xenconsoles);
    spin_unlock(&xencons_lock);

    return 0;
}

static int xen_initial_domain_console_init(void)
{
    struct xencons_info *info;

    if (!xen_initial_domain())
        return -ENODEV;

    info = vtermno_to_xencons(HVC_COOKIE);
    if (!info) {
        info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL | __GFP_ZERO);
        if (!info)
            return -ENOMEM;
    }

    info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
    info->vtermno = HVC_COOKIE;

    spin_lock(&xencons_lock);
    list_add_tail(&info->list, &xenconsoles);
    spin_unlock(&xencons_lock);

    return 0;
}

void xen_console_resume(void)
{
    struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
    if (info != NULL && info->irq)
        rebind_evtchn_irq(info->evtchn, info->irq);
}

static void xencons_disconnect_backend(struct xencons_info *info)
{
    if (info->irq > 0)
        unbind_from_irqhandler(info->irq, NULL);
    info->irq = 0;
    if (info->evtchn > 0)
        xenbus_free_evtchn(info->xbdev, info->evtchn);
    info->evtchn = 0;
    if (info->gntref > 0)
        gnttab_free_grant_references(info->gntref);
    info->gntref = 0;
    if (info->hvc != NULL)
        hvc_remove(info->hvc);
    info->hvc = NULL;
}

static void xencons_free(struct xencons_info *info)
{
    free_page((unsigned long)info->intf);
    info->intf = NULL;
    info->vtermno = 0;
    kfree(info);
}

static int xen_console_remove(struct xencons_info *info)
{
    xencons_disconnect_backend(info);
    spin_lock(&xencons_lock);
    list_del(&info->list);
    spin_unlock(&xencons_lock);
    if (info->xbdev != NULL)
        xencons_free(info);
    else {
        if (xen_hvm_domain())
            iounmap(info->intf);
        kfree(info);
    }
    return 0;
}

#ifdef CONFIG_HVC_XEN_FRONTEND
static struct xenbus_driver xencons_driver;

static int xencons_remove(struct xenbus_device *dev)
{
    return xen_console_remove(dev_get_drvdata(&dev->dev));
}

static int xencons_connect_backend(struct xenbus_device *dev,
                  struct xencons_info *info)
{
    int ret, evtchn, devid, ref, irq;
    struct xenbus_transaction xbt;
    grant_ref_t gref_head;
    unsigned long mfn;

    ret = xenbus_alloc_evtchn(dev, &evtchn);
    if (ret)
        return ret;
    info->evtchn = evtchn;
    irq = bind_evtchn_to_irq(evtchn);
    if (irq < 0)
        return irq;
    info->irq = irq;
    devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
    info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
            irq, &domU_hvc_ops, 256);
    if (IS_ERR(info->hvc))
        return PTR_ERR(info->hvc);
    if (xen_pv_domain())
        mfn = virt_to_mfn(info->intf);
    else
        mfn = __pa(info->intf) >> PAGE_SHIFT;
    ret = gnttab_alloc_grant_references(1, &gref_head);
    if (ret < 0)
        return ret;
    info->gntref = gref_head;
    ref = gnttab_claim_grant_reference(&gref_head);
    if (ref < 0)
        return ref;
    gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
            mfn, 0);

 again:
    ret = xenbus_transaction_start(&xbt);
    if (ret) {
        xenbus_dev_fatal(dev, ret, "starting transaction");
        return ret;
    }
    ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
    if (ret)
        goto error_xenbus;
    ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
                evtchn);
    if (ret)
        goto error_xenbus;
    ret = xenbus_printf(xbt, dev->nodename, "type", "ioemu");
    if (ret)
        goto error_xenbus;
    ret = xenbus_transaction_end(xbt, 0);
    if (ret) {
        if (ret == -EAGAIN)
            goto again;
        xenbus_dev_fatal(dev, ret, "completing transaction");
        return ret;
    }

    xenbus_switch_state(dev, XenbusStateInitialised);
    return 0;

 error_xenbus:
    xenbus_transaction_end(xbt, 1);
    xenbus_dev_fatal(dev, ret, "writing xenstore");
    return ret;
}

static int __devinit xencons_probe(struct xenbus_device *dev,
                  const struct xenbus_device_id *id)
{
    int ret, devid;
    struct xencons_info *info;

    devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
    if (devid == 0)
        return -ENODEV;

    info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
    if (!info)
        return -ENOMEM;
    dev_set_drvdata(&dev->dev, info);
    info->xbdev = dev;
    info->vtermno = xenbus_devid_to_vtermno(devid);
    info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
    if (!info->intf)
        goto error_nomem;

    ret = xencons_connect_backend(dev, info);
    if (ret < 0)
        goto error;
    spin_lock(&xencons_lock);
    list_add_tail(&info->list, &xenconsoles);
    spin_unlock(&xencons_lock);

    return 0;

 error_nomem:
    ret = -ENOMEM;
    xenbus_dev_fatal(dev, ret, "allocating device memory");
 error:
    xencons_disconnect_backend(info);
    xencons_free(info);
    return ret;
}

static int xencons_resume(struct xenbus_device *dev)
{
    struct xencons_info *info = dev_get_drvdata(&dev->dev);

    xencons_disconnect_backend(info);
    memset(info->intf, 0, PAGE_SIZE);
    return xencons_connect_backend(dev, info);
}

static void xencons_backend_changed(struct xenbus_device *dev,
                   enum xenbus_state backend_state)
{
    switch (backend_state) {
    case XenbusStateReconfiguring:
    case XenbusStateReconfigured:
    case XenbusStateInitialising:
    case XenbusStateInitialised:
    case XenbusStateUnknown:
        break;

    case XenbusStateInitWait:
        break;

    case XenbusStateConnected:
        xenbus_switch_state(dev, XenbusStateConnected);
        break;

    case XenbusStateClosed:
        if (dev->state == XenbusStateClosed)
            break;
        /* Missed the backend's CLOSING state -- fallthrough */
    case XenbusStateClosing:
        xenbus_frontend_closed(dev);
        break;
    }
}

static const struct xenbus_device_id xencons_ids[] = {
    { "console" },
    { "" }
};


static DEFINE_XENBUS_DRIVER(xencons, "xenconsole",
    .probe = xencons_probe,
    .remove = xencons_remove,
    .resume = xencons_resume,
    .otherend_changed = xencons_backend_changed,
);
#endif /* CONFIG_HVC_XEN_FRONTEND */

static int __init xen_hvc_init(void)
{
    int r;
    struct xencons_info *info;
    const struct hv_ops *ops;

    if (!xen_domain())
        return -ENODEV;

    if (xen_initial_domain()) {
        ops = &dom0_hvc_ops;
        r = xen_initial_domain_console_init();
        if (r < 0)
            return r;
        info = vtermno_to_xencons(HVC_COOKIE);
    } else {
        ops = &domU_hvc_ops;
        if (xen_hvm_domain())
            r = xen_hvm_console_init();
        else
            r = xen_pv_console_init();
        if (r < 0)
            return r;

        info = vtermno_to_xencons(HVC_COOKIE);
        info->irq = bind_evtchn_to_irq(info->evtchn);
    }
    if (info->irq < 0)
        info->irq = 0; /* NO_IRQ */
    else
        irq_set_noprobe(info->irq);

    info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
    if (IS_ERR(info->hvc)) {
        r = PTR_ERR(info->hvc);
        spin_lock(&xencons_lock);
        list_del(&info->list);
        spin_unlock(&xencons_lock);
        if (info->irq)
            unbind_from_irqhandler(info->irq, NULL);
        kfree(info);
        return r;
    }

    r = 0;
#ifdef CONFIG_HVC_XEN_FRONTEND
    r = xenbus_register_frontend(&xencons_driver);
#endif
    return r;
}

static void __exit xen_hvc_fini(void)
{
    struct xencons_info *entry, *next;

    if (list_empty(&xenconsoles))
            return;

    list_for_each_entry_safe(entry, next, &xenconsoles, list) {
        xen_console_remove(entry);
    }
}

static int xen_cons_init(void)
{
    const struct hv_ops *ops;

    if (!xen_domain())
        return 0;

    if (xen_initial_domain())
        ops = &dom0_hvc_ops;
    else {
        int r;
        ops = &domU_hvc_ops;

        if (xen_hvm_domain())
            r = xen_hvm_console_init();
        else
            r = xen_pv_console_init();
        if (r < 0)
            return r;
    }

    hvc_instantiate(HVC_COOKIE, 0, ops);
    return 0;
}


module_init(xen_hvc_init);
module_exit(xen_hvc_fini);
console_initcall(xen_cons_init);

#ifdef CONFIG_EARLY_PRINTK
static void xenboot_write_console(struct console *console, const char *string,
                  unsigned len)
{
    unsigned int linelen, off = 0;
    const char *pos;

    if (!xen_pv_domain())
        return;

    dom0_write_console(0, string, len);

    if (xen_initial_domain())
        return;

    domU_write_console(0, "(early) ", 8);
    while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
        linelen = pos-string+off;
        if (off + linelen > len)
            break;
        domU_write_console(0, string+off, linelen);
        domU_write_console(0, "\r\n", 2);
        off += linelen + 1;
    }
    if (off < len)
        domU_write_console(0, string+off, len-off);
}

struct console xenboot_console = {
    .name       = "xenboot",
    .write      = xenboot_write_console,
    .flags      = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
};
#endif  /* CONFIG_EARLY_PRINTK */

void xen_raw_console_write(const char *str)
{
    dom0_write_console(0, str, strlen(str));
}

void xen_raw_printk(const char *fmt, ...)
{
    static char buf[512];
    va_list ap;

    va_start(ap, fmt);
    vsnprintf(buf, sizeof(buf), fmt, ap);
    va_end(ap);

    xen_raw_console_write(buf);
}