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 "sysemu/sysemu.h"
  28 #include "chardev/char-fe.h"
  29 #include "hw/xen/xen-legacy-backend.h"
  30
  31 #include "hw/xen/interface/io/console.h"
  32
  33 struct buffer {
  34     uint8_t *data;
  35     size_t consumed;
  36     size_t size;
  37     size_t capacity;
  38     size_t max_capacity;
  39 };
  40
  41 struct XenConsole {
  42     struct XenLegacyDevice  xendev;  /* must be first */
  43     struct buffer     buffer;
  44     char              console[XEN_BUFSIZE];
  45     int               ring_ref;
  46     void              *sring;
  47     CharBackend       chr;
  48     int               backlog;
  49 };
  50
  51 static void buffer_append(struct XenConsole *con)
  52 {
  53     struct buffer *buffer = &con->buffer;
  54     XENCONS_RING_IDX cons, prod, size;
  55     struct xencons_interface *intf = con->sring;
  56
  57     cons = intf->out_cons;
  58     prod = intf->out_prod;
  59     xen_mb();
  60
  61     size = prod - cons;
  62     if ((size == 0) || (size > sizeof(intf->out)))
  63         return;
  64
  65     if ((buffer->capacity - buffer->size) < size) {
  66         buffer->capacity += (size + 1024);
  67         buffer->data = g_realloc(buffer->data, buffer->capacity);
  68     }
  69
  70     while (cons != prod)
  71         buffer->data[buffer->size++] = intf->out[
  72             MASK_XENCONS_IDX(cons++, intf->out)];
  73
  74     xen_mb();
  75     intf->out_cons = cons;
  76     xen_pv_send_notify(&con->xendev);
  77
  78     if (buffer->max_capacity &&
  79         buffer->size > buffer->max_capacity) {
  80         /* Discard the middle of the data. */
  81
  82         size_t over = buffer->size - buffer->max_capacity;
  83         uint8_t *maxpos = buffer->data + buffer->max_capacity;
  84
  85         memmove(maxpos - over, maxpos, over);
  86         buffer->data = g_realloc(buffer->data, buffer->max_capacity);
  87         buffer->size = buffer->capacity = buffer->max_capacity;
  88
  89         if (buffer->consumed > buffer->max_capacity - over)
  90             buffer->consumed = buffer->max_capacity - over;
  91     }
  92 }
  93
  94 static void buffer_advance(struct buffer *buffer, size_t len)
  95 {
  96     buffer->consumed += len;
  97     if (buffer->consumed == buffer->size) {
  98         buffer->consumed = 0;
  99         buffer->size = 0;
 100     }
 101 }
 102
 103 static int ring_free_bytes(struct XenConsole *con)
 104 {
 105     struct xencons_interface *intf = con->sring;
 106     XENCONS_RING_IDX cons, prod, space;
 107
 108     cons = intf->in_cons;
 109     prod = intf->in_prod;
 110     xen_mb();
 111
 112     space = prod - cons;
 113     if (space > sizeof(intf->in))
 114         return 0; /* ring is screwed: ignore it */
 115
 116     return (sizeof(intf->in) - space);
 117 }
 118
 119 static int xencons_can_receive(void *opaque)
 120 {
 121     struct XenConsole *con = opaque;
 122     return ring_free_bytes(con);
 123 }
 124
 125 static void xencons_receive(void *opaque, const uint8_t *buf, int len)
 126 {
 127     struct XenConsole *con = opaque;
 128     struct xencons_interface *intf = con->sring;
 129     XENCONS_RING_IDX prod;
 130     int i, max;
 131
 132     max = ring_free_bytes(con);
 133     /* The can_receive() func limits this, but check again anyway */
 134     if (max < len)
 135         len = max;
 136
 137     prod = intf->in_prod;
 138     for (i = 0; i < len; i++) {
 139         intf->in[MASK_XENCONS_IDX(prod++, intf->in)] =
 140             buf[i];
 141     }
 142     xen_wmb();
 143     intf->in_prod = prod;
 144     xen_pv_send_notify(&con->xendev);
 145 }
 146
 147 static void xencons_send(struct XenConsole *con)
 148 {
 149     ssize_t len, size;
 150
 151     size = con->buffer.size - con->buffer.consumed;
 152     if (qemu_chr_fe_backend_connected(&con->chr)) {
 153         len = qemu_chr_fe_write(&con->chr,
 154                                 con->buffer.data + con->buffer.consumed,
 155                                 size);
 156     } else {
 157         len = size;
 158     }
 159     if (len < 1) {
 160         if (!con->backlog) {
 161             con->backlog = 1;
 162             xen_pv_printf(&con->xendev, 1,
 163                           "backlog piling up, nobody listening?\n");
 164         }
 165     } else {
 166         buffer_advance(&con->buffer, len);
 167         if (con->backlog && len == size) {
 168             con->backlog = 0;
 169             xen_pv_printf(&con->xendev, 1, "backlog is gone\n");
 170         }
 171     }
 172 }
 173
 174 /* -------------------------------------------------------------------- */
 175
 176 static int con_init(struct XenLegacyDevice *xendev)
 177 {
 178     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 179     char *type, *dom, label[32];
 180     int ret = 0;
 181     const char *output;
 182
 183     /* setup */
 184     dom = xs_get_domain_path(xenstore, con->xendev.dom);
 185     if (!xendev->dev) {
 186         snprintf(con->console, sizeof(con->console), "%s/console", dom);
 187     } else {
 188         snprintf(con->console, sizeof(con->console), "%s/device/console/%d", dom, xendev->dev);
 189     }
 190     free(dom);
 191
 192     type = xenstore_read_str(con->console, "type");
 193     if (!type || strcmp(type, "ioemu") != 0) {
 194         xen_pv_printf(xendev, 1, "not for me (type=%s)\n", type);
 195         ret = -1;
 196         goto out;
 197     }
 198
 199     output = xenstore_read_str(con->console, "output");
 200
 201     /* no Xen override, use qemu output device */
 202     if (output == NULL) {
 203         if (con->xendev.dev) {
 204             qemu_chr_fe_init(&con->chr, serial_hd(con->xendev.dev),
 205                              &error_abort);
 206         }
 207     } else {
 208         snprintf(label, sizeof(label), "xencons%d", con->xendev.dev);
 209         qemu_chr_fe_init(&con->chr,
 210                          /*
 211                           * FIXME: sure we want to support implicit
 212                           * muxed monitors here?
 213                           */
 214                          qemu_chr_new_mux_mon(label, output, NULL),
 215                          &error_abort);
 216     }
 217
 218     xenstore_store_pv_console_info(con->xendev.dev,
 219                                    qemu_chr_fe_get_driver(&con->chr));
 220
 221 out:
 222     g_free(type);
 223     return ret;
 224 }
 225
 226 static int con_initialise(struct XenLegacyDevice *xendev)
 227 {
 228     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 229     int limit;
 230
 231     if (xenstore_read_int(con->console, "ring-ref", &con->ring_ref) == -1)
 232         return -1;
 233     if (xenstore_read_int(con->console, "port", &con->xendev.remote_port) == -1)
 234         return -1;
 235     if (xenstore_read_int(con->console, "limit", &limit) == 0)
 236         con->buffer.max_capacity = limit;
 237
 238     if (!xendev->dev) {
 239         xen_pfn_t mfn = con->ring_ref;
 240         con->sring = xenforeignmemory_map(xen_fmem, con->xendev.dom,
 241                                           PROT_READ | PROT_WRITE,
 242                                           1, &mfn, NULL);
 243     } else {
 244         con->sring = xen_be_map_grant_ref(xendev, con->ring_ref,
 245                                           PROT_READ | PROT_WRITE);
 246     }
 247     if (!con->sring)
 248         return -1;
 249
 250     xen_be_bind_evtchn(&con->xendev);
 251     qemu_chr_fe_set_handlers(&con->chr, xencons_can_receive,
 252                              xencons_receive, NULL, NULL, con, NULL, true);
 253
 254     xen_pv_printf(xendev, 1,
 255                   "ring mfn %d, remote port %d, local port %d, limit %zd\n",
 256                   con->ring_ref,
 257                   con->xendev.remote_port,
 258                   con->xendev.local_port,
 259                   con->buffer.max_capacity);
 260     return 0;
 261 }
 262
 263 static void con_disconnect(struct XenLegacyDevice *xendev)
 264 {
 265     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 266
 267     qemu_chr_fe_deinit(&con->chr, false);
 268     xen_pv_unbind_evtchn(&con->xendev);
 269
 270     if (con->sring) {
 271         if (!xendev->dev) {
 272             xenforeignmemory_unmap(xen_fmem, con->sring, 1);
 273         } else {
 274             xen_be_unmap_grant_ref(xendev, con->sring);
 275         }
 276         con->sring = NULL;
 277     }
 278 }
 279
 280 static void con_event(struct XenLegacyDevice *xendev)
 281 {
 282     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 283
 284     buffer_append(con);
 285     if (con->buffer.size - con->buffer.consumed)
 286         xencons_send(con);
 287 }
 288
 289 /* -------------------------------------------------------------------- */
 290
 291 struct XenDevOps xen_console_ops = {
 292     .size       = sizeof(struct XenConsole),
 293     .flags      = DEVOPS_FLAG_IGNORE_STATE|DEVOPS_FLAG_NEED_GNTDEV,
 294     .init       = con_init,
 295     .initialise = con_initialise,
 296     .event      = con_event,
 297     .disconnect = con_disconnect,
 298 };