[Qemu-devel] [PATCH 07/13] xen: add console backend driver.

[Gerd Hoffmann <kraxel@redhat.com>]

This patch adds a xenconsole backend driver.  It it based on current
xen-unstable code.  It has been changed to make use of the common
backend driver code.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 Makefile.target     |    1 +
 hw/xen_backend.h    |    3 +
 hw/xen_console.c    |  271 +++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/xen_machine_pv.c |    3 +
 4 files changed, 278 insertions(+), 0 deletions(-)
 create mode 100644 hw/xen_console.c

diff --git a/Makefile.target b/Makefile.target
index 78a6402..92ad109 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -517,6 +517,7 @@ endif
 
 # xen backend driver support
 XEN_OBJS := xen_machine_pv.o xen_backend.o
+XEN_OBJS += xen_console.o
 ifeq ($(CONFIG_XEN), yes)
   OBJS += $(XEN_OBJS)
   LIBS += $(XEN_LIBS)
diff --git a/hw/xen_backend.h b/hw/xen_backend.h
index 3a79ad0..10bd1a6 100644
--- a/hw/xen_backend.h
+++ b/hw/xen_backend.h
@@ -83,4 +83,7 @@ int xen_be_send_notify(struct XenDevice *xendev);
 void xen_be_printf(struct XenDevice *xendev, int msg_level, const char *fmt, ...)
     __attribute__ ((format(printf, 3, 4)));
 
+/* actual backend drivers */
+struct XenDevOps xen_console_ops;      /* xen_console.c     */
+
 #endif /* QEMU_XEN_BACKEND_H */
diff --git a/hw/xen_console.c b/hw/xen_console.c
new file mode 100644
index 0000000..2ea88f6
--- /dev/null
+++ b/hw/xen_console.c
@@ -0,0 +1,271 @@
+/*
+ *  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, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/select.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <termios.h>
+#include <stdarg.h>
+#include <sys/mman.h>
+#include <xs.h>
+#include <xen/io/console.h>
+#include <xenctrl.h>
+
+#include "hw.h"
+#include "sysemu.h"
+#include "qemu-char.h"
+#include "xen_backend.h"
+
+#define dolog(val, fmt, ...) fprintf(stderr, fmt "\n", ## __VA_ARGS__)
+
+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;
+    CharDriverState   *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 = qemu_realloc(buffer->data, buffer->capacity);
+	if (buffer->data == NULL) {
+	    dolog(LOG_ERR, "Memory allocation failed");
+	    exit(ENOMEM);
+	}
+    }
+
+    while (cons != prod)
+	buffer->data[buffer->size++] = intf->out[
+	    MASK_XENCONS_IDX(cons++, intf->out)];
+
+    xen_mb();
+    intf->out_cons = cons;
+    xen_be_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 = qemu_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_be_send_notify(&con->xendev);
+}
+
+static void xencons_send(struct XenConsole *con)
+{
+    ssize_t len, size;
+
+    size = con->buffer.size - con->buffer.consumed;
+    len = qemu_chr_write(con->chr, con->buffer.data + con->buffer.consumed,
+			 size);
+    if (len < 1) {
+	if (!con->backlog) {
+	    con->backlog = 1;
+	    xen_be_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_be_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;
+
+    if (!serial_hds[con->xendev.dev]) {
+	xen_be_printf(xendev, 1, "serial line %d not configured\n", con->xendev.dev);
+	return -1;
+    }
+
+    /* setup */
+    dom = xs_get_domain_path(xenstore, con->xendev.dom);
+    snprintf(con->console, sizeof(con->console), "%s/console", dom);
+    free(dom);
+    con->chr = serial_hds[con->xendev.dev];
+
+    type = xenstore_read_str(con->console, "type");
+    if (!type || 0 != strcmp(type, "ioemu")) {
+	xen_be_printf(xendev, 1, "not for me (type=%s)\n", type);
+	return -1;
+    }
+
+    return 0;
+}
+
+static int con_connect(struct XenDevice *xendev)
+{
+    struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
+    int limit;
+
+    if (-1 == xenstore_read_int(con->console, "ring-ref", &con->ring_ref))
+	return -1;
+    if (-1 == xenstore_read_int(con->console, "port", &con->xendev.remote_port))
+	return -1;
+    if (0 == xenstore_read_int(con->console, "limit", &limit))
+	con->buffer.max_capacity = limit;
+
+    con->sring = xc_map_foreign_range(xen_xc, con->xendev.dom,
+				      XC_PAGE_SIZE,
+				      PROT_READ|PROT_WRITE,
+				      con->ring_ref);
+    if (!con->sring)
+	return -1;
+
+    xen_be_bind_evtchn(&con->xendev);
+    qemu_chr_add_handlers(con->chr, xencons_can_receive, xencons_receive,
+			  NULL, con);
+
+    xen_be_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_add_handlers(con->chr, NULL, NULL, NULL, NULL);
+    xen_be_unbind_evtchn(&con->xendev);
+
+    if (con->sring) {
+	munmap(con->sring, XC_PAGE_SIZE);
+	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,
+    .init       = con_init,
+    .connect    = con_connect,
+    .event      = con_event,
+    .disconnect = con_disconnect,
+};
diff --git a/hw/xen_machine_pv.c b/hw/xen_machine_pv.c
index 2eceb8e..93f66d0 100644
--- a/hw/xen_machine_pv.c
+++ b/hw/xen_machine_pv.c
@@ -97,6 +97,9 @@ static int xen_init_pv(DisplayState *ds)
     if (rc < 0)
         return rc;
 
+    /* xenbus backend drivers */
+    xen_be_register("console", &xen_console_ops);
+
     return 0;
 }
 
-- 
1.5.5.1