text: /*
   *  Copyright (C) International Business Machines  Corp., 2005
   *  Author(s): Anthony Liguori <aliguori@us.ibm.com>
   *
   *  Copyright (C) Red Hat 2007
   *
   *  Xen Console
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation; under version 2 of the License.
   *
   *  This program is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *  GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License along
   *  with this program; if not, see <http://www.gnu.org/licenses/>.
   */
  
  #include "qemu/osdep.h"
  #include <sys/select.h>
  #include <termios.h>
  
  #include "qapi/error.h"
  #include "hw/hw.h"
  #include "chardev/char-fe.h"
  #include "hw/xen/xen_backend.h"
  
  #include <xen/io/console.h>
  
  struct buffer {
      uint8_t *data;
      size_t consumed;
      size_t size;
      size_t capacity;
      size_t max_capacity;
  };
  
  struct XenConsole {
      struct XenDevice  xendev;  /* must be first */
      struct buffer     buffer;
      char              console[XEN_BUFSIZE];
      int               ring_ref;
      void              *sring;
      CharBackend       chr;
      int               backlog;
  };
  
  static void buffer_append(struct XenConsole *con)
  {
      struct buffer *buffer = &con->buffer;
      XENCONS_RING_IDX cons, prod, size;
      struct xencons_interface *intf = con->sring;
  
      cons = intf->out_cons;
      prod = intf->out_prod;
      xen_mb();
  
      size = prod - cons;
      if ((size == 0) || (size > sizeof(intf->out)))
  	return;
  
      if ((buffer->capacity - buffer->size) < size) {
  	buffer->capacity += (size + 1024);
  	buffer->data = g_realloc(buffer->data, buffer->capacity);
      }
  
      while (cons != prod)
  	buffer->data[buffer->size++] = intf->out[
  	    MASK_XENCONS_IDX(cons++, intf->out)];
  
      xen_mb();
      intf->out_cons = cons;
      xen_pv_send_notify(&con->xendev);
  
      if (buffer->max_capacity &&
  	buffer->size > buffer->max_capacity) {
  	/* Discard the middle of the data. */
  
  	size_t over = buffer->size - buffer->max_capacity;
  	uint8_t *maxpos = buffer->data + buffer->max_capacity;
  
  	memmove(maxpos - over, maxpos, over);
  	buffer->data = g_realloc(buffer->data, buffer->max_capacity);
  	buffer->size = buffer->capacity = buffer->max_capacity;
  
  	if (buffer->consumed > buffer->max_capacity - over)
  	    buffer->consumed = buffer->max_capacity - over;
      }
  }
  
  static void buffer_advance(struct buffer *buffer, size_t len)
  {
      buffer->consumed += len;
      if (buffer->consumed == buffer->size) {
  	buffer->consumed = 0;
  	buffer->size = 0;
      }
  }
  
  static int ring_free_bytes(struct XenConsole *con)
  {
      struct xencons_interface *intf = con->sring;
      XENCONS_RING_IDX cons, prod, space;
  
      cons = intf->in_cons;
      prod = intf->in_prod;
      xen_mb();
  
      space = prod - cons;
      if (space > sizeof(intf->in))
  	return 0; /* ring is screwed: ignore it */
  
      return (sizeof(intf->in) - space);
  }
  
  static int xencons_can_receive(void *opaque)
  {
      struct XenConsole *con = opaque;
      return ring_free_bytes(con);
  }
  
  static void xencons_receive(void *opaque, const uint8_t *buf, int len)
  {
      struct XenConsole *con = opaque;
      struct xencons_interface *intf = con->sring;
      XENCONS_RING_IDX prod;
      int i, max;
  
      max = ring_free_bytes(con);
      /* The can_receive() func limits this, but check again anyway */
      if (max < len)
  	len = max;
  
      prod = intf->in_prod;
      for (i = 0; i < len; i++) {
  	intf->in[MASK_XENCONS_IDX(prod++, intf->in)] =
  	    buf[i];
      }
      xen_wmb();
      intf->in_prod = prod;
      xen_pv_send_notify(&con->xendev);
  }
  
  static void xencons_send(struct XenConsole *con)
  {
      ssize_t len, size;
  
      size = con->buffer.size - con->buffer.consumed;
      if (qemu_chr_fe_backend_connected(&con->chr)) {
          len = qemu_chr_fe_write(&con->chr,
                                  con->buffer.data + con->buffer.consumed,
                                  size);
      } else {
          len = size;
      }
      if (len < 1) {
          if (!con->backlog) {
              con->backlog = 1;
              xen_pv_printf(&con->xendev, 1,
                            "backlog piling up, nobody listening?\n");
          }
      } else {
          buffer_advance(&con->buffer, len);
          if (con->backlog && len == size) {
              con->backlog = 0;
              xen_pv_printf(&con->xendev, 1, "backlog is gone\n");
          }
      }
  }
  
  /* -------------------------------------------------------------------- */
  
  static int con_init(struct XenDevice *xendev)
  {
      struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
      char *type, *dom, label[32];
      int ret = 0;
      const char *output;
  
      /* setup */
      dom = xs_get_domain_path(xenstore, con->xendev.dom);
      if (!xendev->dev) {
          snprintf(con->console, sizeof(con->console), "%s/console", dom);
      } else {
          snprintf(con->console, sizeof(con->console), "%s/device/console/%d", dom, xendev->dev);
      }
      free(dom);
  
      type = xenstore_read_str(con->console, "type");
      if (!type || strcmp(type, "ioemu") != 0) {
          xen_pv_printf(xendev, 1, "not for me (type=%s)\n", type);
          ret = -1;
          goto out;
      }
  
      output = xenstore_read_str(con->console, "output");
  
      /* no Xen override, use qemu output device */
      if (output == NULL) {
          if (con->xendev.dev) {
              qemu_chr_fe_init(&con->chr, serial_hd(con->xendev.dev),
                               &error_abort);
          }
      } else {
          snprintf(label, sizeof(label), "xencons%d", con->xendev.dev);
          qemu_chr_fe_init(&con->chr,
                           /*
                            * FIXME: sure we want to support implicit
                            * muxed monitors here?
                            */
                           qemu_chr_new_mux_mon(label, output), &error_abort);
      }
  
      xenstore_store_pv_console_info(con->xendev.dev,
                                     qemu_chr_fe_get_driver(&con->chr));
  
  out:
      g_free(type);
      return ret;
  }
  
  static int con_initialise(struct XenDevice *xendev)
  {
      struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
      int limit;
  
      if (xenstore_read_int(con->console, "ring-ref", &con->ring_ref) == -1)
  	return -1;
      if (xenstore_read_int(con->console, "port", &con->xendev.remote_port) == -1)
  	return -1;
      if (xenstore_read_int(con->console, "limit", &limit) == 0)
  	con->buffer.max_capacity = limit;
  
      if (!xendev->dev) {
          xen_pfn_t mfn = con->ring_ref;
          con->sring = xenforeignmemory_map(xen_fmem, con->xendev.dom,
                                            PROT_READ | PROT_WRITE,
                                            1, &mfn, NULL);
      } else {
          con->sring = xen_be_map_grant_ref(xendev, con->ring_ref,
                                            PROT_READ | PROT_WRITE);
      }
      if (!con->sring)
  	return -1;
  
      xen_be_bind_evtchn(&con->xendev);
      qemu_chr_fe_set_handlers(&con->chr, xencons_can_receive,
                               xencons_receive, NULL, NULL, con, NULL, true);
  
      xen_pv_printf(xendev, 1,
                    "ring mfn %d, remote port %d, local port %d, limit %zd\n",
  		  con->ring_ref,
  		  con->xendev.remote_port,
  		  con->xendev.local_port,
  		  con->buffer.max_capacity);
      return 0;
  }
  
  static void con_disconnect(struct XenDevice *xendev)
  {
      struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
  
      qemu_chr_fe_deinit(&con->chr, false);
      xen_pv_unbind_evtchn(&con->xendev);
  
      if (con->sring) {
          if (!xendev->dev) {
              xenforeignmemory_unmap(xen_fmem, con->sring, 1);
          } else {
              xen_be_unmap_grant_ref(xendev, con->sring);
          }
          con->sring = NULL;
      }
  }
  
  static void con_event(struct XenDevice *xendev)
  {
      struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
  
      buffer_append(con);
      if (con->buffer.size - con->buffer.consumed)
  	xencons_send(con);
  }
  
  /* -------------------------------------------------------------------- */
  
  struct XenDevOps xen_console_ops = {
      .size       = sizeof(struct XenConsole),
      .flags      = DEVOPS_FLAG_IGNORE_STATE|DEVOPS_FLAG_NEED_GNTDEV,
      .init       = con_init,
      .initialise = con_initialise,
      .event      = con_event,
      .disconnect = con_disconnect,
  };
  