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
  32 #include "hw.h"
  33 #include "qemu-char.h"
  34 #include "xen_backend.h"
  35
  36 #include <xen/io/console.h>
  37
  38 struct buffer {
  39     uint8_t *data;
  40     size_t consumed;
  41     size_t size;
  42     size_t capacity;
  43     size_t max_capacity;
  44 };
  45
  46 struct XenConsole {
  47     struct XenDevice  xendev;  /* must be first */
  48     struct buffer     buffer;
  49     char              console[XEN_BUFSIZE];
  50     int               ring_ref;
  51     void              *sring;
  52     CharDriverState   *chr;
  53     int               backlog;
  54 };
  55
  56 static void buffer_append(struct XenConsole *con)
  57 {
  58     struct buffer *buffer = &con->buffer;
  59     XENCONS_RING_IDX cons, prod, size;
  60     struct xencons_interface *intf = con->sring;
  61
  62     cons = intf->out_cons;
  63     prod = intf->out_prod;
  64     xen_mb();
  65
  66     size = prod - cons;
  67     if ((size == 0) || (size > sizeof(intf->out)))
  68         return;
  69
  70     if ((buffer->capacity - buffer->size) < size) {
  71         buffer->capacity += (size + 1024);
  72         buffer->data = g_realloc(buffer->data, buffer->capacity);
  73     }
  74
  75     while (cons != prod)
  76         buffer->data[buffer->size++] = intf->out[
  77             MASK_XENCONS_IDX(cons++, intf->out)];
  78
  79     xen_mb();
  80     intf->out_cons = cons;
  81     xen_be_send_notify(&con->xendev);
  82
  83     if (buffer->max_capacity &&
  84         buffer->size > buffer->max_capacity) {
  85         /* Discard the middle of the data. */
  86
  87         size_t over = buffer->size - buffer->max_capacity;
  88         uint8_t *maxpos = buffer->data + buffer->max_capacity;
  89
  90         memmove(maxpos - over, maxpos, over);
  91         buffer->data = g_realloc(buffer->data, buffer->max_capacity);
  92         buffer->size = buffer->capacity = buffer->max_capacity;
  93
  94         if (buffer->consumed > buffer->max_capacity - over)
  95             buffer->consumed = buffer->max_capacity - over;
  96     }
  97 }
  98
  99 static void buffer_advance(struct buffer *buffer, size_t len)
 100 {
 101     buffer->consumed += len;
 102     if (buffer->consumed == buffer->size) {
 103         buffer->consumed = 0;
 104         buffer->size = 0;
 105     }
 106 }
 107
 108 static int ring_free_bytes(struct XenConsole *con)
 109 {
 110     struct xencons_interface *intf = con->sring;
 111     XENCONS_RING_IDX cons, prod, space;
 112
 113     cons = intf->in_cons;
 114     prod = intf->in_prod;
 115     xen_mb();
 116
 117     space = prod - cons;
 118     if (space > sizeof(intf->in))
 119         return 0; /* ring is screwed: ignore it */
 120
 121     return (sizeof(intf->in) - space);
 122 }
 123
 124 static int xencons_can_receive(void *opaque)
 125 {
 126     struct XenConsole *con = opaque;
 127     return ring_free_bytes(con);
 128 }
 129
 130 static void xencons_receive(void *opaque, const uint8_t *buf, int len)
 131 {
 132     struct XenConsole *con = opaque;
 133     struct xencons_interface *intf = con->sring;
 134     XENCONS_RING_IDX prod;
 135     int i, max;
 136
 137     max = ring_free_bytes(con);
 138     /* The can_receive() func limits this, but check again anyway */
 139     if (max < len)
 140         len = max;
 141
 142     prod = intf->in_prod;
 143     for (i = 0; i < len; i++) {
 144         intf->in[MASK_XENCONS_IDX(prod++, intf->in)] =
 145             buf[i];
 146     }
 147     xen_wmb();
 148     intf->in_prod = prod;
 149     xen_be_send_notify(&con->xendev);
 150 }
 151
 152 static void xencons_send(struct XenConsole *con)
 153 {
 154     ssize_t len, size;
 155
 156     size = con->buffer.size - con->buffer.consumed;
 157     if (con->chr)
 158         len = qemu_chr_fe_write(con->chr, con->buffer.data + con->buffer.consumed,
 159                              size);
 160     else
 161         len = size;
 162     if (len < 1) {
 163         if (!con->backlog) {
 164             con->backlog = 1;
 165             xen_be_printf(&con->xendev, 1, "backlog piling up, nobody listening?\n");
 166         }
 167     } else {
 168         buffer_advance(&con->buffer, len);
 169         if (con->backlog && len == size) {
 170             con->backlog = 0;
 171             xen_be_printf(&con->xendev, 1, "backlog is gone\n");
 172         }
 173     }
 174 }
 175
 176 /* -------------------------------------------------------------------- */
 177
 178 static int con_init(struct XenDevice *xendev)
 179 {
 180     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 181     char *type, *dom, label[32];
 182     int ret = 0;
 183     const char *output;
 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         ret = -1;
 194         goto out;
 195     }
 196
 197     output = xenstore_read_str(con->console, "output");
 198
 199     /* no Xen override, use qemu output device */
 200     if (output == NULL) {
 201         con->chr = serial_hds[con->xendev.dev];
 202     } else {
 203         snprintf(label, sizeof(label), "xencons%d", con->xendev.dev);
 204         con->chr = qemu_chr_new(label, output, NULL);
 205     }
 206
 207     xenstore_store_pv_console_info(con->xendev.dev, con->chr);
 208
 209 out:
 210     g_free(type);
 211     return ret;
 212 }
 213
 214 static int con_initialise(struct XenDevice *xendev)
 215 {
 216     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 217     int limit;
 218
 219     if (xenstore_read_int(con->console, "ring-ref", &con->ring_ref) == -1)
 220         return -1;
 221     if (xenstore_read_int(con->console, "port", &con->xendev.remote_port) == -1)
 222         return -1;
 223     if (xenstore_read_int(con->console, "limit", &limit) == 0)
 224         con->buffer.max_capacity = limit;
 225
 226     con->sring = xc_map_foreign_range(xen_xc, con->xendev.dom,
 227                                       XC_PAGE_SIZE,
 228                                       PROT_READ|PROT_WRITE,
 229                                       con->ring_ref);
 230     if (!con->sring)
 231         return -1;
 232
 233     xen_be_bind_evtchn(&con->xendev);
 234     if (con->chr)
 235         qemu_chr_add_handlers(con->chr, xencons_can_receive, xencons_receive,
 236                               NULL, con);
 237
 238     xen_be_printf(xendev, 1, "ring mfn %d, remote port %d, local port %d, limit %zd\n",
 239                   con->ring_ref,
 240                   con->xendev.remote_port,
 241                   con->xendev.local_port,
 242                   con->buffer.max_capacity);
 243     return 0;
 244 }
 245
 246 static void con_disconnect(struct XenDevice *xendev)
 247 {
 248     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 249
 250     if (!xendev->dev) {
 251         return;
 252     }
 253     if (con->chr)
 254         qemu_chr_add_handlers(con->chr, NULL, NULL, NULL, NULL);
 255     xen_be_unbind_evtchn(&con->xendev);
 256
 257     if (con->sring) {
 258         munmap(con->sring, XC_PAGE_SIZE);
 259         con->sring = NULL;
 260     }
 261 }
 262
 263 static void con_event(struct XenDevice *xendev)
 264 {
 265     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 266
 267     buffer_append(con);
 268     if (con->buffer.size - con->buffer.consumed)
 269         xencons_send(con);
 270 }
 271
 272 /* -------------------------------------------------------------------- */
 273
 274 struct XenDevOps xen_console_ops = {
 275     .size       = sizeof(struct XenConsole),
 276     .flags      = DEVOPS_FLAG_IGNORE_STATE,
 277     .init       = con_init,
 278     .initialise = con_initialise,
 279     .event      = con_event,
 280     .disconnect = con_disconnect,
 281 };