hw/xen_console.c

   1 /*
   2  *  Copyright (C) International Business Machines  Corp., 2005
   3  *  Author(s): Anthony Liguori <aliguori@us.ibm.com>
   4  *
   5  *  Copyright (C) Red Hat 2007
   6  *
   7  *  Xen Console
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License as published by
  11  *  the Free Software Foundation; under version 2 of the License.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License along
  19  *  with this program; if not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include <stdlib.h>
  23 #include <errno.h>
  24 #include <string.h>
  25 #include <sys/select.h>
  26 #include <fcntl.h>
  27 #include <unistd.h>
  28 #include <termios.h>
  29 #include <stdarg.h>
  30 #include <sys/mman.h>
  31 #include <xs.h>
  32 #include <xen/io/console.h>
  33 #include <xenctrl.h>
  34
  35 #include "hw.h"
  36 #include "sysemu.h"
  37 #include "qemu-char.h"
  38 #include "xen_backend.h"
  39
  40 struct buffer {
  41     uint8_t *data;
  42     size_t consumed;
  43     size_t size;
  44     size_t capacity;
  45     size_t max_capacity;
  46 };
  47
  48 struct XenConsole {
  49     struct XenDevice  xendev;  /* must be first */
  50     struct buffer     buffer;
  51     char              console[XEN_BUFSIZE];
  52     int               ring_ref;
  53     void              *sring;
  54     CharDriverState   *chr;
  55     int               backlog;
  56 };
  57
  58 static void buffer_append(struct XenConsole *con)
  59 {
  60     struct buffer *buffer = &con->buffer;
  61     XENCONS_RING_IDX cons, prod, size;
  62     struct xencons_interface *intf = con->sring;
  63
  64     cons = intf->out_cons;
  65     prod = intf->out_prod;
  66     xen_mb();
  67
  68     size = prod - cons;
  69     if ((size == 0) || (size > sizeof(intf->out)))
  70         return;
  71
  72     if ((buffer->capacity - buffer->size) < size) {
  73         buffer->capacity += (size + 1024);
  74         buffer->data = qemu_realloc(buffer->data, buffer->capacity);
  75     }
  76
  77     while (cons != prod)
  78         buffer->data[buffer->size++] = intf->out[
  79             MASK_XENCONS_IDX(cons++, intf->out)];
  80
  81     xen_mb();
  82     intf->out_cons = cons;
  83     xen_be_send_notify(&con->xendev);
  84
  85     if (buffer->max_capacity &&
  86         buffer->size > buffer->max_capacity) {
  87         /* Discard the middle of the data. */
  88
  89         size_t over = buffer->size - buffer->max_capacity;
  90         uint8_t *maxpos = buffer->data + buffer->max_capacity;
  91
  92         memmove(maxpos - over, maxpos, over);
  93         buffer->data = qemu_realloc(buffer->data, buffer->max_capacity);
  94         buffer->size = buffer->capacity = buffer->max_capacity;
  95
  96         if (buffer->consumed > buffer->max_capacity - over)
  97             buffer->consumed = buffer->max_capacity - over;
  98     }
  99 }
 100
 101 static void buffer_advance(struct buffer *buffer, size_t len)
 102 {
 103     buffer->consumed += len;
 104     if (buffer->consumed == buffer->size) {
 105         buffer->consumed = 0;
 106         buffer->size = 0;
 107     }
 108 }
 109
 110 static int ring_free_bytes(struct XenConsole *con)
 111 {
 112     struct xencons_interface *intf = con->sring;
 113     XENCONS_RING_IDX cons, prod, space;
 114
 115     cons = intf->in_cons;
 116     prod = intf->in_prod;
 117     xen_mb();
 118
 119     space = prod - cons;
 120     if (space > sizeof(intf->in))
 121         return 0; /* ring is screwed: ignore it */
 122
 123     return (sizeof(intf->in) - space);
 124 }
 125
 126 static int xencons_can_receive(void *opaque)
 127 {
 128     struct XenConsole *con = opaque;
 129     return ring_free_bytes(con);
 130 }
 131
 132 static void xencons_receive(void *opaque, const uint8_t *buf, int len)
 133 {
 134     struct XenConsole *con = opaque;
 135     struct xencons_interface *intf = con->sring;
 136     XENCONS_RING_IDX prod;
 137     int i, max;
 138
 139     max = ring_free_bytes(con);
 140     /* The can_receive() func limits this, but check again anyway */
 141     if (max < len)
 142         len = max;
 143
 144     prod = intf->in_prod;
 145     for (i = 0; i < len; i++) {
 146         intf->in[MASK_XENCONS_IDX(prod++, intf->in)] =
 147             buf[i];
 148     }
 149     xen_wmb();
 150     intf->in_prod = prod;
 151     xen_be_send_notify(&con->xendev);
 152 }
 153
 154 static void xencons_send(struct XenConsole *con)
 155 {
 156     ssize_t len, size;
 157
 158     size = con->buffer.size - con->buffer.consumed;
 159     if (con->chr)
 160         len = qemu_chr_write(con->chr, con->buffer.data + con->buffer.consumed,
 161                              size);
 162     else
 163         len = size;
 164     if (len < 1) {
 165         if (!con->backlog) {
 166             con->backlog = 1;
 167             xen_be_printf(&con->xendev, 1, "backlog piling up, nobody listening?\n");
 168         }
 169     } else {
 170         buffer_advance(&con->buffer, len);
 171         if (con->backlog && len == size) {
 172             con->backlog = 0;
 173             xen_be_printf(&con->xendev, 1, "backlog is gone\n");
 174         }
 175     }
 176 }
 177
 178 /* -------------------------------------------------------------------- */
 179
 180 static int con_init(struct XenDevice *xendev)
 181 {
 182     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 183     char *type, *dom;
 184
 185     /* setup */
 186     dom = xs_get_domain_path(xenstore, con->xendev.dom);
 187     snprintf(con->console, sizeof(con->console), "%s/console", dom);
 188     free(dom);
 189
 190     type = xenstore_read_str(con->console, "type");
 191     if (!type || strcmp(type, "ioemu") != 0) {
 192         xen_be_printf(xendev, 1, "not for me (type=%s)\n", type);
 193         return -1;
 194     }
 195
 196     if (!serial_hds[con->xendev.dev])
 197         xen_be_printf(xendev, 1, "WARNING: serial line %d not configured\n",
 198                       con->xendev.dev);
 199     else
 200         con->chr = serial_hds[con->xendev.dev];
 201
 202     return 0;
 203 }
 204
 205 static int con_connect(struct XenDevice *xendev)
 206 {
 207     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 208     int limit;
 209
 210     if (xenstore_read_int(con->console, "ring-ref", &con->ring_ref) == -1)
 211         return -1;
 212     if (xenstore_read_int(con->console, "port", &con->xendev.remote_port) == -1)
 213         return -1;
 214     if (xenstore_read_int(con->console, "limit", &limit) == 0)
 215         con->buffer.max_capacity = limit;
 216
 217     con->sring = xc_map_foreign_range(xen_xc, con->xendev.dom,
 218                                       XC_PAGE_SIZE,
 219                                       PROT_READ|PROT_WRITE,
 220                                       con->ring_ref);
 221     if (!con->sring)
 222         return -1;
 223
 224     xen_be_bind_evtchn(&con->xendev);
 225     if (con->chr)
 226         qemu_chr_add_handlers(con->chr, xencons_can_receive, xencons_receive,
 227                               NULL, con);
 228
 229     xen_be_printf(xendev, 1, "ring mfn %d, remote port %d, local port %d, limit %zd\n",
 230                   con->ring_ref,
 231                   con->xendev.remote_port,
 232                   con->xendev.local_port,
 233                   con->buffer.max_capacity);
 234     return 0;
 235 }
 236
 237 static void con_disconnect(struct XenDevice *xendev)
 238 {
 239     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 240
 241     if (con->chr)
 242         qemu_chr_add_handlers(con->chr, NULL, NULL, NULL, NULL);
 243     xen_be_unbind_evtchn(&con->xendev);
 244
 245     if (con->sring) {
 246         munmap(con->sring, XC_PAGE_SIZE);
 247         con->sring = NULL;
 248     }
 249 }
 250
 251 static void con_event(struct XenDevice *xendev)
 252 {
 253     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 254
 255     buffer_append(con);
 256     if (con->buffer.size - con->buffer.consumed)
 257         xencons_send(con);
 258 }
 259
 260 /* -------------------------------------------------------------------- */
 261
 262 struct XenDevOps xen_console_ops = {
 263     .size       = sizeof(struct XenConsole),
 264     .flags      = DEVOPS_FLAG_IGNORE_STATE,
 265     .init       = con_init,
 266     .connect    = con_connect,
 267     .event      = con_event,
 268     .disconnect = con_disconnect,
 269 };