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 "qemu/osdep.h"
  23 #include <sys/select.h>
  24 #include <termios.h>
  25
  26 #include "qapi/error.h"
  27 #include "hw/hw.h"
  28 #include "chardev/char-fe.h"
  29 #include "hw/xen/xen_backend.h"
  30 #include "qapi/error.h"
  31
  32 #include <xen/io/console.h>
  33
  34 struct buffer {
  35     uint8_t *data;
  36     size_t consumed;
  37     size_t size;
  38     size_t capacity;
  39     size_t max_capacity;
  40 };
  41
  42 struct XenConsole {
  43     struct XenDevice  xendev;  /* must be first */
  44     struct buffer     buffer;
  45     char              console[XEN_BUFSIZE];
  46     int               ring_ref;
  47     void              *sring;
  48     CharBackend       chr;
  49     int               backlog;
  50 };
  51
  52 static void buffer_append(struct XenConsole *con)
  53 {
  54     struct buffer *buffer = &con->buffer;
  55     XENCONS_RING_IDX cons, prod, size;
  56     struct xencons_interface *intf = con->sring;
  57
  58     cons = intf->out_cons;
  59     prod = intf->out_prod;
  60     xen_mb();
  61
  62     size = prod - cons;
  63     if ((size == 0) || (size > sizeof(intf->out)))
  64         return;
  65
  66     if ((buffer->capacity - buffer->size) < size) {
  67         buffer->capacity += (size + 1024);
  68         buffer->data = g_realloc(buffer->data, buffer->capacity);
  69     }
  70
  71     while (cons != prod)
  72         buffer->data[buffer->size++] = intf->out[
  73             MASK_XENCONS_IDX(cons++, intf->out)];
  74
  75     xen_mb();
  76     intf->out_cons = cons;
  77     xen_pv_send_notify(&con->xendev);
  78
  79     if (buffer->max_capacity &&
  80         buffer->size > buffer->max_capacity) {
  81         /* Discard the middle of the data. */
  82
  83         size_t over = buffer->size - buffer->max_capacity;
  84         uint8_t *maxpos = buffer->data + buffer->max_capacity;
  85
  86         memmove(maxpos - over, maxpos, over);
  87         buffer->data = g_realloc(buffer->data, buffer->max_capacity);
  88         buffer->size = buffer->capacity = buffer->max_capacity;
  89
  90         if (buffer->consumed > buffer->max_capacity - over)
  91             buffer->consumed = buffer->max_capacity - over;
  92     }
  93 }
  94
  95 static void buffer_advance(struct buffer *buffer, size_t len)
  96 {
  97     buffer->consumed += len;
  98     if (buffer->consumed == buffer->size) {
  99         buffer->consumed = 0;
 100         buffer->size = 0;
 101     }
 102 }
 103
 104 static int ring_free_bytes(struct XenConsole *con)
 105 {
 106     struct xencons_interface *intf = con->sring;
 107     XENCONS_RING_IDX cons, prod, space;
 108
 109     cons = intf->in_cons;
 110     prod = intf->in_prod;
 111     xen_mb();
 112
 113     space = prod - cons;
 114     if (space > sizeof(intf->in))
 115         return 0; /* ring is screwed: ignore it */
 116
 117     return (sizeof(intf->in) - space);
 118 }
 119
 120 static int xencons_can_receive(void *opaque)
 121 {
 122     struct XenConsole *con = opaque;
 123     return ring_free_bytes(con);
 124 }
 125
 126 static void xencons_receive(void *opaque, const uint8_t *buf, int len)
 127 {
 128     struct XenConsole *con = opaque;
 129     struct xencons_interface *intf = con->sring;
 130     XENCONS_RING_IDX prod;
 131     int i, max;
 132
 133     max = ring_free_bytes(con);
 134     /* The can_receive() func limits this, but check again anyway */
 135     if (max < len)
 136         len = max;
 137
 138     prod = intf->in_prod;
 139     for (i = 0; i < len; i++) {
 140         intf->in[MASK_XENCONS_IDX(prod++, intf->in)] =
 141             buf[i];
 142     }
 143     xen_wmb();
 144     intf->in_prod = prod;
 145     xen_pv_send_notify(&con->xendev);
 146 }
 147
 148 static void xencons_send(struct XenConsole *con)
 149 {
 150     ssize_t len, size;
 151
 152     size = con->buffer.size - con->buffer.consumed;
 153     if (qemu_chr_fe_backend_connected(&con->chr)) {
 154         len = qemu_chr_fe_write(&con->chr,
 155                                 con->buffer.data + con->buffer.consumed,
 156                                 size);
 157     } else {
 158         len = size;
 159     }
 160     if (len < 1) {
 161         if (!con->backlog) {
 162             con->backlog = 1;
 163             xen_pv_printf(&con->xendev, 1,
 164                           "backlog piling up, nobody listening?\n");
 165         }
 166     } else {
 167         buffer_advance(&con->buffer, len);
 168         if (con->backlog && len == size) {
 169             con->backlog = 0;
 170             xen_pv_printf(&con->xendev, 1, "backlog is gone\n");
 171         }
 172     }
 173 }
 174
 175 /* -------------------------------------------------------------------- */
 176
 177 static int con_init(struct XenDevice *xendev)
 178 {
 179     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 180     char *type, *dom, label[32];
 181     int ret = 0;
 182     const char *output;
 183
 184     /* setup */
 185     dom = xs_get_domain_path(xenstore, con->xendev.dom);
 186     if (!xendev->dev) {
 187         snprintf(con->console, sizeof(con->console), "%s/console", dom);
 188     } else {
 189         snprintf(con->console, sizeof(con->console), "%s/device/console/%d", dom, xendev->dev);
 190     }
 191     free(dom);
 192
 193     type = xenstore_read_str(con->console, "type");
 194     if (!type || strcmp(type, "ioemu") != 0) {
 195         xen_pv_printf(xendev, 1, "not for me (type=%s)\n", type);
 196         ret = -1;
 197         goto out;
 198     }
 199
 200     output = xenstore_read_str(con->console, "output");
 201
 202     /* no Xen override, use qemu output device */
 203     if (output == NULL) {
 204         if (con->xendev.dev) {
 205             qemu_chr_fe_init(&con->chr, serial_hds[con->xendev.dev],
 206                              &error_abort);
 207         }
 208     } else {
 209         snprintf(label, sizeof(label), "xencons%d", con->xendev.dev);
 210         qemu_chr_fe_init(&con->chr,
 211                          qemu_chr_new(label, output), &error_abort);
 212     }
 213
 214     xenstore_store_pv_console_info(con->xendev.dev,
 215                                    qemu_chr_fe_get_driver(&con->chr));
 216
 217 out:
 218     g_free(type);
 219     return ret;
 220 }
 221
 222 static int con_initialise(struct XenDevice *xendev)
 223 {
 224     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 225     int limit;
 226
 227     if (xenstore_read_int(con->console, "ring-ref", &con->ring_ref) == -1)
 228         return -1;
 229     if (xenstore_read_int(con->console, "port", &con->xendev.remote_port) == -1)
 230         return -1;
 231     if (xenstore_read_int(con->console, "limit", &limit) == 0)
 232         con->buffer.max_capacity = limit;
 233
 234     if (!xendev->dev) {
 235         xen_pfn_t mfn = con->ring_ref;
 236         con->sring = xenforeignmemory_map(xen_fmem, con->xendev.dom,
 237                                           PROT_READ|PROT_WRITE,
 238                                           1, &mfn, NULL);
 239     } else {
 240         con->sring = xengnttab_map_grant_ref(xendev->gnttabdev, con->xendev.dom,
 241                                              con->ring_ref,
 242                                              PROT_READ|PROT_WRITE);
 243     }
 244     if (!con->sring)
 245         return -1;
 246
 247     xen_be_bind_evtchn(&con->xendev);
 248     qemu_chr_fe_set_handlers(&con->chr, xencons_can_receive,
 249                              xencons_receive, NULL, NULL, con, NULL, true);
 250
 251     xen_pv_printf(xendev, 1,
 252                   "ring mfn %d, remote port %d, local port %d, limit %zd\n",
 253                   con->ring_ref,
 254                   con->xendev.remote_port,
 255                   con->xendev.local_port,
 256                   con->buffer.max_capacity);
 257     return 0;
 258 }
 259
 260 static void con_disconnect(struct XenDevice *xendev)
 261 {
 262     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 263
 264     qemu_chr_fe_deinit(&con->chr, false);
 265     xen_pv_unbind_evtchn(&con->xendev);
 266
 267     if (con->sring) {
 268         if (!xendev->dev) {
 269             xenforeignmemory_unmap(xen_fmem, con->sring, 1);
 270         } else {
 271             xengnttab_unmap(xendev->gnttabdev, con->sring, 1);
 272         }
 273         con->sring = NULL;
 274     }
 275 }
 276
 277 static void con_event(struct XenDevice *xendev)
 278 {
 279     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 280
 281     buffer_append(con);
 282     if (con->buffer.size - con->buffer.consumed)
 283         xencons_send(con);
 284 }
 285
 286 /* -------------------------------------------------------------------- */
 287
 288 struct XenDevOps xen_console_ops = {
 289     .size       = sizeof(struct XenConsole),
 290     .flags      = DEVOPS_FLAG_IGNORE_STATE|DEVOPS_FLAG_NEED_GNTDEV,
 291     .init       = con_init,
 292     .initialise = con_initialise,
 293     .event      = con_event,
 294     .disconnect = con_disconnect,
 295 };