Archipelago » qemu

/*

 *  Copyright (C) International Business Machines  Corp., 2005

 *  Author(s): Anthony Liguori <aliguori@us.ibm.com>

 *

 *  Copyright (C) Red Hat 2007

 *

 *  Xen Console

 *

 *  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; under version 2 of the License.

 *

 *  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, see <http://www.gnu.org/licenses/>.

 */

#include <stdlib.h>

#include <errno.h>

#include <string.h>

#include <sys/select.h>

#include <fcntl.h>

#include <unistd.h>

#include <termios.h>

#include <stdarg.h>

#include <sys/mman.h>

#include <xs.h>

#include <xen/io/console.h>

#include <xenctrl.h>

#include "hw.h"

#include "qemu-char.h"

#include "xen_backend.h"

struct buffer {

    uint8_t *data;

    size_t consumed;

    size_t size;

    size_t capacity;

    size_t max_capacity;

};

struct XenConsole {

    struct XenDevice  xendev;  /* must be first */

    struct buffer     buffer;

    char              console[XEN_BUFSIZE];

    int               ring_ref;

    void              *sring;

    CharDriverState   *chr;

    int               backlog;

};

static void buffer_append(struct XenConsole *con)

{

    struct buffer *buffer = &con->buffer;

    XENCONS_RING_IDX cons, prod, size;

    struct xencons_interface *intf = con->sring;

    cons = intf->out_cons;

    prod = intf->out_prod;

    xen_mb();

    size = prod - cons;

    if ((size == 0) || (size > sizeof(intf->out)))

        return;

    if ((buffer->capacity - buffer->size) < size) {

        buffer->capacity += (size + 1024);

        buffer->data = qemu_realloc(buffer->data, buffer->capacity);

    }

    while (cons != prod)

        buffer->data[buffer->size++] = intf->out[

            MASK_XENCONS_IDX(cons++, intf->out)];

    xen_mb();

    intf->out_cons = cons;

    xen_be_send_notify(&con->xendev);

    if (buffer->max_capacity &&

        buffer->size > buffer->max_capacity) {

        /* Discard the middle of the data. */

        size_t over = buffer->size - buffer->max_capacity;

        uint8_t *maxpos = buffer->data + buffer->max_capacity;

        memmove(maxpos - over, maxpos, over);

        buffer->data = qemu_realloc(buffer->data, buffer->max_capacity);

        buffer->size = buffer->capacity = buffer->max_capacity;

        if (buffer->consumed > buffer->max_capacity - over)

            buffer->consumed = buffer->max_capacity - over;

    }

}

static void buffer_advance(struct buffer *buffer, size_t len)

{

    buffer->consumed += len;

    if (buffer->consumed == buffer->size) {

        buffer->consumed = 0;

        buffer->size = 0;

    }

}

static int ring_free_bytes(struct XenConsole *con)

{

    struct xencons_interface *intf = con->sring;

    XENCONS_RING_IDX cons, prod, space;

    cons = intf->in_cons;

    prod = intf->in_prod;

    xen_mb();

    space = prod - cons;

    if (space > sizeof(intf->in))

        return 0; /* ring is screwed: ignore it */

    return (sizeof(intf->in) - space);

}

static int xencons_can_receive(void *opaque)

{

    struct XenConsole *con = opaque;

    return ring_free_bytes(con);

}

static void xencons_receive(void *opaque, const uint8_t *buf, int len)

{

    struct XenConsole *con = opaque;

    struct xencons_interface *intf = con->sring;

    XENCONS_RING_IDX prod;

    int i, max;

    max = ring_free_bytes(con);

    /* The can_receive() func limits this, but check again anyway */

    if (max < len)

        len = max;

    prod = intf->in_prod;

    for (i = 0; i < len; i++) {

        intf->in[MASK_XENCONS_IDX(prod++, intf->in)] =

            buf[i];

    }

    xen_wmb();

    intf->in_prod = prod;

    xen_be_send_notify(&con->xendev);

}

static void xencons_send(struct XenConsole *con)

{

    ssize_t len, size;

    size = con->buffer.size - con->buffer.consumed;

    if (con->chr)

        len = qemu_chr_write(con->chr, con->buffer.data + con->buffer.consumed,

                             size);

    else

        len = size;

    if (len < 1) {

        if (!con->backlog) {

            con->backlog = 1;

            xen_be_printf(&con->xendev, 1, "backlog piling up, nobody listening?\n");

        }

    } else {

        buffer_advance(&con->buffer, len);

        if (con->backlog && len == size) {

            con->backlog = 0;

            xen_be_printf(&con->xendev, 1, "backlog is gone\n");

        }

    }

}

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

static int con_init(struct XenDevice *xendev)

{

    struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);

    char *type, *dom, label[32];

    int ret = 0;

    const char *output;

    /* setup */

    dom = xs_get_domain_path(xenstore, con->xendev.dom);

    snprintf(con->console, sizeof(con->console), "%s/console", dom);

    free(dom);

    type = xenstore_read_str(con->console, "type");

    if (!type || strcmp(type, "ioemu") != 0) {

        xen_be_printf(xendev, 1, "not for me (type=%s)\n", type);

        ret = -1;

        goto out;

    }

    output = xenstore_read_str(con->console, "output");

    /* output is a pty by default */

    if (output == NULL) {

        output = "pty";

    }

    snprintf(label, sizeof(label), "xencons%d", con->xendev.dev);

    con->chr = qemu_chr_open(label, output, NULL);

    xenstore_store_pv_console_info(con->xendev.dev, con->chr);

out:

    qemu_free(type);

    return ret;

}

static int con_connect(struct XenDevice *xendev)

{

    struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);

    int limit;

    if (xenstore_read_int(con->console, "ring-ref", &con->ring_ref) == -1)

        return -1;

    if (xenstore_read_int(con->console, "port", &con->xendev.remote_port) == -1)

        return -1;

    if (xenstore_read_int(con->console, "limit", &limit) == 0)

        con->buffer.max_capacity = limit;

    con->sring = xc_map_foreign_range(xen_xc, con->xendev.dom,

                                      XC_PAGE_SIZE,

                                      PROT_READ|PROT_WRITE,

                                      con->ring_ref);

    if (!con->sring)

        return -1;

    xen_be_bind_evtchn(&con->xendev);

    if (con->chr)

        qemu_chr_add_handlers(con->chr, xencons_can_receive, xencons_receive,

                              NULL, con);

    xen_be_printf(xendev, 1, "ring mfn %d, remote port %d, local port %d, limit %zd\n",

                  con->ring_ref,

                  con->xendev.remote_port,

                  con->xendev.local_port,

                  con->buffer.max_capacity);

    return 0;

}

static void con_disconnect(struct XenDevice *xendev)

{

    struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);

    if (con->chr)

        qemu_chr_add_handlers(con->chr, NULL, NULL, NULL, NULL);

    xen_be_unbind_evtchn(&con->xendev);

    if (con->sring) {

        munmap(con->sring, XC_PAGE_SIZE);

        con->sring = NULL;

    }

}

static void con_event(struct XenDevice *xendev)

{

    struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);

    buffer_append(con);

    if (con->buffer.size - con->buffer.consumed)

        xencons_send(con);

}

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

struct XenDevOps xen_console_ops = {

    .size       = sizeof(struct XenConsole),

    .flags      = DEVOPS_FLAG_IGNORE_STATE,

    .init       = con_init,

    .connect    = con_connect,

    .event      = con_event,

    .disconnect = con_disconnect,

};