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 "qemu-char.h"
  37 #include "xen_backend.h"
  38
  39 struct buffer {
  40     uint8_t *data;
  41     size_t consumed;
  42     size_t size;
  43     size_t capacity;
  44     size_t max_capacity;
  45 };
  46
  47 struct XenConsole {
  48     struct XenDevice  xendev;  /* must be first */
  49     struct buffer     buffer;
  50     char              console[XEN_BUFSIZE];
  51     int               ring_ref;
  52     void              *sring;
  53     CharDriverState   *chr;
  54     int               backlog;
  55 };
  56
  57 static void buffer_append(struct XenConsole *con)
  58 {
  59     struct buffer *buffer = &con->buffer;
  60     XENCONS_RING_IDX cons, prod, size;
  61     struct xencons_interface *intf = con->sring;
  62
  63     cons = intf->out_cons;
  64     prod = intf->out_prod;
  65     xen_mb();
  66
  67     size = prod - cons;
  68     if ((size == 0) || (size > sizeof(intf->out)))
  69         return;
  70
  71     if ((buffer->capacity - buffer->size) < size) {
  72         buffer->capacity += (size + 1024);
  73         buffer->data = g_realloc(buffer->data, buffer->capacity);
  74     }
  75
  76     while (cons != prod)
  77         buffer->data[buffer->size++] = intf->out[
  78             MASK_XENCONS_IDX(cons++, intf->out)];
  79
  80     xen_mb();
  81     intf->out_cons = cons;
  82     xen_be_send_notify(&con->xendev);
  83
  84     if (buffer->max_capacity &&
  85         buffer->size > buffer->max_capacity) {
  86         /* Discard the middle of the data. */
  87
  88         size_t over = buffer->size - buffer->max_capacity;
  89         uint8_t *maxpos = buffer->data + buffer->max_capacity;
  90
  91         memmove(maxpos - over, maxpos, over);
  92         buffer->data = g_realloc(buffer->data, buffer->max_capacity);
  93         buffer->size = buffer->capacity = buffer->max_capacity;
  94
  95         if (buffer->consumed > buffer->max_capacity - over)
  96             buffer->consumed = buffer->max_capacity - over;
  97     }
  98 }
  99
 100 static void buffer_advance(struct buffer *buffer, size_t len)
 101 {
 102     buffer->consumed += len;
 103     if (buffer->consumed == buffer->size) {
 104         buffer->consumed = 0;
 105         buffer->size = 0;
 106     }
 107 }
 108
 109 static int ring_free_bytes(struct XenConsole *con)
 110 {
 111     struct xencons_interface *intf = con->sring;
 112     XENCONS_RING_IDX cons, prod, space;
 113
 114     cons = intf->in_cons;
 115     prod = intf->in_prod;
 116     xen_mb();
 117
 118     space = prod - cons;
 119     if (space > sizeof(intf->in))
 120         return 0; /* ring is screwed: ignore it */
 121
 122     return (sizeof(intf->in) - space);
 123 }
 124
 125 static int xencons_can_receive(void *opaque)
 126 {
 127     struct XenConsole *con = opaque;
 128     return ring_free_bytes(con);
 129 }
 130
 131 static void xencons_receive(void *opaque, const uint8_t *buf, int len)
 132 {
 133     struct XenConsole *con = opaque;
 134     struct xencons_interface *intf = con->sring;
 135     XENCONS_RING_IDX prod;
 136     int i, max;
 137
 138     max = ring_free_bytes(con);
 139     /* The can_receive() func limits this, but check again anyway */
 140     if (max < len)
 141         len = max;
 142
 143     prod = intf->in_prod;
 144     for (i = 0; i < len; i++) {
 145         intf->in[MASK_XENCONS_IDX(prod++, intf->in)] =
 146             buf[i];
 147     }
 148     xen_wmb();
 149     intf->in_prod = prod;
 150     xen_be_send_notify(&con->xendev);
 151 }
 152
 153 static void xencons_send(struct XenConsole *con)
 154 {
 155     ssize_t len, size;
 156
 157     size = con->buffer.size - con->buffer.consumed;
 158     if (con->chr)
 159         len = qemu_chr_write(con->chr, con->buffer.data + con->buffer.consumed,
 160                              size);
 161     else
 162         len = size;
 163     if (len < 1) {
 164         if (!con->backlog) {
 165             con->backlog = 1;
 166             xen_be_printf(&con->xendev, 1, "backlog piling up, nobody listening?\n");
 167         }
 168     } else {
 169         buffer_advance(&con->buffer, len);
 170         if (con->backlog && len == size) {
 171             con->backlog = 0;
 172             xen_be_printf(&con->xendev, 1, "backlog is gone\n");
 173         }
 174     }
 175 }
 176
 177 /* -------------------------------------------------------------------- */
 178
 179 static int con_init(struct XenDevice *xendev)
 180 {
 181     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 182     char *type, *dom, label[32];
 183     int ret = 0;
 184     const char *output;
 185
 186     /* setup */
 187     dom = xs_get_domain_path(xenstore, con->xendev.dom);
 188     snprintf(con->console, sizeof(con->console), "%s/console", dom);
 189     free(dom);
 190
 191     type = xenstore_read_str(con->console, "type");
 192     if (!type || strcmp(type, "ioemu") != 0) {
 193         xen_be_printf(xendev, 1, "not for me (type=%s)\n", type);
 194         ret = -1;
 195         goto out;
 196     }
 197
 198     output = xenstore_read_str(con->console, "output");
 199
 200     /* no Xen override, use qemu output device */
 201     if (output == NULL) {
 202         con->chr = serial_hds[con->xendev.dev];
 203     } else {
 204         snprintf(label, sizeof(label), "xencons%d", con->xendev.dev);
 205         con->chr = qemu_chr_open(label, output, NULL);
 206     }
 207
 208     xenstore_store_pv_console_info(con->xendev.dev, con->chr);
 209
 210 out:
 211     g_free(type);
 212     return ret;
 213 }
 214
 215 static int con_connect(struct XenDevice *xendev)
 216 {
 217     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 218     int limit;
 219
 220     if (xenstore_read_int(con->console, "ring-ref", &con->ring_ref) == -1)
 221         return -1;
 222     if (xenstore_read_int(con->console, "port", &con->xendev.remote_port) == -1)
 223         return -1;
 224     if (xenstore_read_int(con->console, "limit", &limit) == 0)
 225         con->buffer.max_capacity = limit;
 226
 227     con->sring = xc_map_foreign_range(xen_xc, con->xendev.dom,
 228                                       XC_PAGE_SIZE,
 229                                       PROT_READ|PROT_WRITE,
 230                                       con->ring_ref);
 231     if (!con->sring)
 232         return -1;
 233
 234     xen_be_bind_evtchn(&con->xendev);
 235     if (con->chr)
 236         qemu_chr_add_handlers(con->chr, xencons_can_receive, xencons_receive,
 237                               NULL, con);
 238
 239     xen_be_printf(xendev, 1, "ring mfn %d, remote port %d, local port %d, limit %zd\n",
 240                   con->ring_ref,
 241                   con->xendev.remote_port,
 242                   con->xendev.local_port,
 243                   con->buffer.max_capacity);
 244     return 0;
 245 }
 246
 247 static void con_disconnect(struct XenDevice *xendev)
 248 {
 249     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 250
 251     if (con->chr)
 252         qemu_chr_add_handlers(con->chr, NULL, NULL, NULL, NULL);
 253     xen_be_unbind_evtchn(&con->xendev);
 254
 255     if (con->sring) {
 256         munmap(con->sring, XC_PAGE_SIZE);
 257         con->sring = NULL;
 258     }
 259 }
 260
 261 static void con_event(struct XenDevice *xendev)
 262 {
 263     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 264
 265     buffer_append(con);
 266     if (con->buffer.size - con->buffer.consumed)
 267         xencons_send(con);
 268 }
 269
 270 /* -------------------------------------------------------------------- */
 271
 272 struct XenDevOps xen_console_ops = {
 273     .size       = sizeof(struct XenConsole),
 274     .flags      = DEVOPS_FLAG_IGNORE_STATE,
 275     .init       = con_init,
 276     .connect    = con_connect,
 277     .event      = con_event,
 278     .disconnect = con_disconnect,
 279 };