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