hw/char/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/hw.h"
  33 #include "sysemu/char.h"
  34 #include "hw/xen/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     if (!xendev->dev) {
 188         snprintf(con->console, sizeof(con->console), "%s/console", dom);
 189     } else {
 190         snprintf(con->console, sizeof(con->console), "%s/device/console/%d", dom, xendev->dev);
 191     }
 192     free(dom);
 193
 194     type = xenstore_read_str(con->console, "type");
 195     if (!type || strcmp(type, "ioemu") != 0) {
 196         xen_be_printf(xendev, 1, "not for me (type=%s)\n", type);
 197         ret = -1;
 198         goto out;
 199     }
 200
 201     output = xenstore_read_str(con->console, "output");
 202
 203     /* no Xen override, use qemu output device */
 204     if (output == NULL) {
 205         con->chr = serial_hds[con->xendev.dev];
 206     } else {
 207         snprintf(label, sizeof(label), "xencons%d", con->xendev.dev);
 208         con->chr = qemu_chr_new(label, output, NULL);
 209     }
 210
 211     xenstore_store_pv_console_info(con->xendev.dev, con->chr);
 212
 213 out:
 214     g_free(type);
 215     return ret;
 216 }
 217
 218 static int con_initialise(struct XenDevice *xendev)
 219 {
 220     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 221     int limit;
 222
 223     if (xenstore_read_int(con->console, "ring-ref", &con->ring_ref) == -1)
 224         return -1;
 225     if (xenstore_read_int(con->console, "port", &con->xendev.remote_port) == -1)
 226         return -1;
 227     if (xenstore_read_int(con->console, "limit", &limit) == 0)
 228         con->buffer.max_capacity = limit;
 229
 230     if (!xendev->dev) {
 231         con->sring = xc_map_foreign_range(xen_xc, con->xendev.dom,
 232                                           XC_PAGE_SIZE,
 233                                           PROT_READ|PROT_WRITE,
 234                                           con->ring_ref);
 235     } else {
 236         con->sring = xc_gnttab_map_grant_ref(xendev->gnttabdev, con->xendev.dom,
 237                                              con->ring_ref,
 238                                              PROT_READ|PROT_WRITE);
 239     }
 240     if (!con->sring)
 241         return -1;
 242
 243     xen_be_bind_evtchn(&con->xendev);
 244     if (con->chr) {
 245         if (qemu_chr_fe_claim(con->chr) == 0) {
 246             qemu_chr_add_handlers(con->chr, xencons_can_receive,
 247                                   xencons_receive, NULL, con);
 248         } else {
 249             xen_be_printf(xendev, 0,
 250                           "xen_console_init error chardev %s already used\n",
 251                           con->chr->label);
 252             con->chr = NULL;
 253         }
 254     }
 255
 256     xen_be_printf(xendev, 1, "ring mfn %d, remote port %d, local port %d, limit %zd\n",
 257                   con->ring_ref,
 258                   con->xendev.remote_port,
 259                   con->xendev.local_port,
 260                   con->buffer.max_capacity);
 261     return 0;
 262 }
 263
 264 static void con_disconnect(struct XenDevice *xendev)
 265 {
 266     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 267
 268     if (!xendev->dev) {
 269         return;
 270     }
 271     if (con->chr) {
 272         qemu_chr_add_handlers(con->chr, NULL, NULL, NULL, NULL);
 273         qemu_chr_fe_release(con->chr);
 274     }
 275     xen_be_unbind_evtchn(&con->xendev);
 276
 277     if (con->sring) {
 278         if (!xendev->gnttabdev) {
 279             munmap(con->sring, XC_PAGE_SIZE);
 280         } else {
 281             xc_gnttab_munmap(xendev->gnttabdev, con->sring, 1);
 282         }
 283         con->sring = NULL;
 284     }
 285 }
 286
 287 static void con_event(struct XenDevice *xendev)
 288 {
 289     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 290
 291     buffer_append(con);
 292     if (con->buffer.size - con->buffer.consumed)
 293         xencons_send(con);
 294 }
 295
 296 /* -------------------------------------------------------------------- */
 297
 298 struct XenDevOps xen_console_ops = {
 299     .size       = sizeof(struct XenConsole),
 300     .flags      = DEVOPS_FLAG_IGNORE_STATE|DEVOPS_FLAG_NEED_GNTDEV,
 301     .init       = con_init,
 302     .initialise = con_initialise,
 303     .event      = con_event,
 304     .disconnect = con_disconnect,
 305 };