qemu/hw/char/xen_console.c
Zhao Liu 0a81424def hw/char/xen_console: Fix missing ERRP_GUARD() for error_prepend()
As the comment in qapi/error, passing @errp to error_prepend() requires
ERRP_GUARD():

* = Why, when and how to use ERRP_GUARD() =
*
* Without ERRP_GUARD(), use of the @errp parameter is restricted:
...
* - It should not be passed to error_prepend(), error_vprepend() or
*   error_append_hint(), because that doesn't work with &error_fatal.
* ERRP_GUARD() lifts these restrictions.
*
* To use ERRP_GUARD(), add it right at the beginning of the function.
* @errp can then be used without worrying about the argument being
* NULL or &error_fatal.

ERRP_GUARD() could avoid the case when @errp is the pointer of
error_fatal, the user can't see this additional information, because
exit() happens in error_setg earlier than information is added [1].

The xen_console_connect() passes @errp to error_prepend() without
ERRP_GUARD().

There're 2 places will call xen_console_connect():
 - xen_console_realize(): the @errp is from DeviceClass.realize()'s
			  parameter.
 - xen_console_frontend_changed(): the @errp points its caller's
                                   @local_err.

To avoid the issue like [1] said, add missing ERRP_GUARD() at the
beginning of xen_console_connect().

[1]: Issue description in the commit message of commit ae7c80a7bd
     ("error: New macro ERRP_GUARD()").

Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Paul Durrant <paul@xen.org>
Cc: "Marc-André Lureau" <marcandre.lureau@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Message-ID: <20240228163723.1775791-15-zhao1.liu@linux.intel.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
2024-03-09 18:51:45 +01:00

646 lines
19 KiB
C

/*
* 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 "qemu/cutils.h"
#include <sys/select.h>
#include <termios.h>
#include "qapi/error.h"
#include "sysemu/sysemu.h"
#include "chardev/char-fe.h"
#include "hw/xen/xen-backend.h"
#include "hw/xen/xen-bus-helper.h"
#include "hw/qdev-properties.h"
#include "hw/qdev-properties-system.h"
#include "hw/xen/interface/io/console.h"
#include "hw/xen/interface/io/xs_wire.h"
#include "hw/xen/interface/grant_table.h"
#include "hw/i386/kvm/xen_primary_console.h"
#include "trace.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 */
XenEventChannel *event_channel;
int dev;
struct buffer buffer;
char *fe_path;
unsigned int ring_ref;
void *sring;
CharBackend chr;
int backlog;
};
typedef struct XenConsole XenConsole;
#define TYPE_XEN_CONSOLE_DEVICE "xen-console"
OBJECT_DECLARE_SIMPLE_TYPE(XenConsole, XEN_CONSOLE_DEVICE)
static bool buffer_append(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 false;
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_device_notify_event_channel(XEN_DEVICE(con), con->event_channel, NULL);
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;
}
return true;
}
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(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)
{
XenConsole *con = opaque;
return ring_free_bytes(con);
}
static void xencons_receive(void *opaque, const uint8_t *buf, int len)
{
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_device_notify_event_channel(XEN_DEVICE(con), con->event_channel, NULL);
}
static bool xencons_send(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;
}
} else {
buffer_advance(&con->buffer, len);
if (con->backlog && len == size) {
con->backlog = 0;
}
}
return len > 0;
}
/* -------------------------------------------------------------------- */
static bool con_event(void *_xendev)
{
XenConsole *con = XEN_CONSOLE_DEVICE(_xendev);
bool done_something;
if (xen_device_backend_get_state(&con->xendev) != XenbusStateConnected) {
return false;
}
done_something = buffer_append(con);
if (con->buffer.size - con->buffer.consumed) {
done_something |= xencons_send(con);
}
return done_something;
}
/* -------------------------------------------------------------------- */
static bool xen_console_connect(XenDevice *xendev, Error **errp)
{
ERRP_GUARD();
XenConsole *con = XEN_CONSOLE_DEVICE(xendev);
unsigned int port, limit;
if (xen_device_frontend_scanf(xendev, "ring-ref", "%u",
&con->ring_ref) != 1) {
error_setg(errp, "failed to read ring-ref");
return false;
}
if (xen_device_frontend_scanf(xendev, "port", "%u", &port) != 1) {
error_setg(errp, "failed to read remote port");
return false;
}
if (xen_device_frontend_scanf(xendev, "limit", "%u", &limit) == 1) {
con->buffer.max_capacity = limit;
}
con->event_channel = xen_device_bind_event_channel(xendev, port,
con_event,
con,
errp);
if (!con->event_channel) {
return false;
}
switch (con->dev) {
case 0:
/*
* The primary console is special. For real Xen the ring-ref is
* actually a GFN which needs to be mapped as foreignmem.
*/
if (xen_mode != XEN_EMULATE) {
xen_pfn_t mfn = (xen_pfn_t)con->ring_ref;
con->sring = qemu_xen_foreignmem_map(xendev->frontend_id, NULL,
PROT_READ | PROT_WRITE,
1, &mfn, NULL);
if (!con->sring) {
error_setg(errp, "failed to map console page");
return false;
}
break;
}
/*
* For Xen emulation, we still follow the convention of ring-ref
* holding the GFN, but we map the fixed GNTTAB_RESERVED_CONSOLE
* grant ref because there is no implementation of foreignmem
* operations for emulated mode. The emulation code which handles
* the guest-side page and event channel also needs to be informed
* of the backend event channel port, in order to reconnect to it
* after a soft reset.
*/
xen_primary_console_set_be_port(
xen_event_channel_get_local_port(con->event_channel));
con->ring_ref = GNTTAB_RESERVED_CONSOLE;
/* fallthrough */
default:
con->sring = xen_device_map_grant_refs(xendev,
&con->ring_ref, 1,
PROT_READ | PROT_WRITE,
errp);
if (!con->sring) {
error_prepend(errp, "failed to map console grant ref: ");
return false;
}
break;
}
trace_xen_console_connect(con->dev, con->ring_ref, port,
con->buffer.max_capacity);
qemu_chr_fe_set_handlers(&con->chr, xencons_can_receive,
xencons_receive, NULL, NULL, con, NULL,
true);
return true;
}
static void xen_console_disconnect(XenDevice *xendev, Error **errp)
{
XenConsole *con = XEN_CONSOLE_DEVICE(xendev);
trace_xen_console_disconnect(con->dev);
qemu_chr_fe_set_handlers(&con->chr, NULL, NULL, NULL, NULL,
con, NULL, true);
if (con->event_channel) {
xen_device_unbind_event_channel(xendev, con->event_channel,
errp);
con->event_channel = NULL;
if (xen_mode == XEN_EMULATE && !con->dev) {
xen_primary_console_set_be_port(0);
}
}
if (con->sring) {
if (!con->dev && xen_mode != XEN_EMULATE) {
qemu_xen_foreignmem_unmap(con->sring, 1);
} else {
xen_device_unmap_grant_refs(xendev, con->sring,
&con->ring_ref, 1, errp);
}
con->sring = NULL;
}
}
static void xen_console_frontend_changed(XenDevice *xendev,
enum xenbus_state frontend_state,
Error **errp)
{
ERRP_GUARD();
enum xenbus_state backend_state = xen_device_backend_get_state(xendev);
switch (frontend_state) {
case XenbusStateInitialised:
case XenbusStateConnected:
if (backend_state == XenbusStateConnected) {
break;
}
xen_console_disconnect(xendev, errp);
if (*errp) {
break;
}
if (!xen_console_connect(xendev, errp)) {
xen_device_backend_set_state(xendev, XenbusStateClosing);
break;
}
xen_device_backend_set_state(xendev, XenbusStateConnected);
break;
case XenbusStateClosing:
xen_device_backend_set_state(xendev, XenbusStateClosing);
break;
case XenbusStateClosed:
case XenbusStateUnknown:
xen_console_disconnect(xendev, errp);
if (*errp) {
break;
}
xen_device_backend_set_state(xendev, XenbusStateClosed);
break;
default:
break;
}
}
static char *xen_console_get_name(XenDevice *xendev, Error **errp)
{
XenConsole *con = XEN_CONSOLE_DEVICE(xendev);
if (con->dev == -1) {
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
char fe_path[XENSTORE_ABS_PATH_MAX + 1];
int idx = (xen_mode == XEN_EMULATE) ? 0 : 1;
char *value;
/* Theoretically we could go up to INT_MAX here but that's overkill */
while (idx < 100) {
if (!idx) {
snprintf(fe_path, sizeof(fe_path),
"/local/domain/%u/console", xendev->frontend_id);
} else {
snprintf(fe_path, sizeof(fe_path),
"/local/domain/%u/device/console/%u",
xendev->frontend_id, idx);
}
value = qemu_xen_xs_read(xenbus->xsh, XBT_NULL, fe_path, NULL);
if (!value) {
if (errno == ENOENT) {
con->dev = idx;
goto found;
}
error_setg(errp, "cannot read %s: %s", fe_path,
strerror(errno));
return NULL;
}
free(value);
idx++;
}
error_setg(errp, "cannot find device index for console device");
return NULL;
}
found:
return g_strdup_printf("%u", con->dev);
}
static void xen_console_unrealize(XenDevice *xendev)
{
XenConsole *con = XEN_CONSOLE_DEVICE(xendev);
trace_xen_console_unrealize(con->dev);
/* Disconnect from the frontend in case this has not already happened */
xen_console_disconnect(xendev, NULL);
qemu_chr_fe_deinit(&con->chr, false);
}
static void xen_console_realize(XenDevice *xendev, Error **errp)
{
ERRP_GUARD();
XenConsole *con = XEN_CONSOLE_DEVICE(xendev);
Chardev *cs = qemu_chr_fe_get_driver(&con->chr);
unsigned int u;
if (!cs) {
error_setg(errp, "no backing character device");
return;
}
if (con->dev == -1) {
error_setg(errp, "no device index provided");
return;
}
/*
* The Xen primary console is special. The ring-ref is actually a GFN to
* be mapped directly as foreignmem (not a grant ref), and the guest port
* was allocated *for* the guest by the toolstack. The guest gets these
* through HVMOP_get_param and can use the console long before it's got
* XenStore up and running. We cannot create those for a true Xen guest,
* but we can for Xen emulation.
*/
if (!con->dev) {
if (xen_mode == XEN_EMULATE) {
xen_primary_console_create();
} else if (xen_device_frontend_scanf(xendev, "ring-ref", "%u", &u)
!= 1 ||
xen_device_frontend_scanf(xendev, "port", "%u", &u) != 1) {
error_setg(errp, "cannot create primary Xen console");
return;
}
}
trace_xen_console_realize(con->dev, object_get_typename(OBJECT(cs)));
if (CHARDEV_IS_PTY(cs)) {
/* Strip the leading 'pty:' */
xen_device_frontend_printf(xendev, "tty", "%s", cs->filename + 4);
}
/* No normal PV driver initialization for the primary console under Xen */
if (!con->dev && xen_mode != XEN_EMULATE) {
xen_console_connect(xendev, errp);
}
}
static char *console_frontend_path(struct qemu_xs_handle *xenstore,
unsigned int dom_id, unsigned int dev)
{
if (!dev) {
return g_strdup_printf("/local/domain/%u/console", dom_id);
} else {
return g_strdup_printf("/local/domain/%u/device/console/%u", dom_id,
dev);
}
}
static char *xen_console_get_frontend_path(XenDevice *xendev, Error **errp)
{
XenConsole *con = XEN_CONSOLE_DEVICE(xendev);
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
char *ret = console_frontend_path(xenbus->xsh, xendev->frontend_id,
con->dev);
if (!ret) {
error_setg(errp, "failed to create frontend path");
}
return ret;
}
static Property xen_console_properties[] = {
DEFINE_PROP_CHR("chardev", XenConsole, chr),
DEFINE_PROP_INT32("idx", XenConsole, dev, -1),
DEFINE_PROP_END_OF_LIST(),
};
static void xen_console_class_init(ObjectClass *class, void *data)
{
DeviceClass *dev_class = DEVICE_CLASS(class);
XenDeviceClass *xendev_class = XEN_DEVICE_CLASS(class);
xendev_class->backend = "console";
xendev_class->device = "console";
xendev_class->get_name = xen_console_get_name;
xendev_class->realize = xen_console_realize;
xendev_class->frontend_changed = xen_console_frontend_changed;
xendev_class->unrealize = xen_console_unrealize;
xendev_class->get_frontend_path = xen_console_get_frontend_path;
device_class_set_props(dev_class, xen_console_properties);
}
static const TypeInfo xen_console_type_info = {
.name = TYPE_XEN_CONSOLE_DEVICE,
.parent = TYPE_XEN_DEVICE,
.instance_size = sizeof(XenConsole),
.class_init = xen_console_class_init,
};
static void xen_console_register_types(void)
{
type_register_static(&xen_console_type_info);
}
type_init(xen_console_register_types)
/* Called to instantiate a XenConsole when the backend is detected. */
static void xen_console_device_create(XenBackendInstance *backend,
QDict *opts, Error **errp)
{
ERRP_GUARD();
XenBus *xenbus = xen_backend_get_bus(backend);
const char *name = xen_backend_get_name(backend);
unsigned long number;
char *fe = NULL, *type = NULL, *output = NULL;
char label[32];
XenDevice *xendev = NULL;
XenConsole *con;
Chardev *cd = NULL;
struct qemu_xs_handle *xsh = xenbus->xsh;
if (qemu_strtoul(name, NULL, 10, &number) || number > INT_MAX) {
error_setg(errp, "failed to parse name '%s'", name);
goto fail;
}
trace_xen_console_device_create(number);
fe = console_frontend_path(xsh, xen_domid, number);
if (fe == NULL) {
error_setg(errp, "failed to generate frontend path");
goto fail;
}
if (xs_node_scanf(xsh, XBT_NULL, fe, "type", errp, "%ms", &type) != 1) {
error_prepend(errp, "failed to read console device type: ");
goto fail;
}
if (strcmp(type, "ioemu")) {
error_setg(errp, "declining to handle console type '%s'",
type);
goto fail;
}
xendev = XEN_DEVICE(qdev_new(TYPE_XEN_CONSOLE_DEVICE));
con = XEN_CONSOLE_DEVICE(xendev);
con->dev = number;
snprintf(label, sizeof(label), "xencons%ld", number);
if (xs_node_scanf(xsh, XBT_NULL, fe, "output", NULL, "%ms", &output) == 1) {
/*
* FIXME: sure we want to support implicit
* muxed monitors here?
*/
cd = qemu_chr_new_mux_mon(label, output, NULL);
if (!cd) {
error_setg(errp, "console: No valid chardev found at '%s': ",
output);
goto fail;
}
} else if (number) {
cd = serial_hd(number);
if (!cd) {
error_prepend(errp, "console: No serial device #%ld found: ",
number);
goto fail;
}
} else {
/* No 'output' node on primary console: use null. */
cd = qemu_chr_new(label, "null", NULL);
if (!cd) {
error_setg(errp, "console: failed to create null device");
goto fail;
}
}
if (!qemu_chr_fe_init(&con->chr, cd, errp)) {
error_prepend(errp, "console: failed to initialize backing chardev: ");
goto fail;
}
if (qdev_realize_and_unref(DEVICE(xendev), BUS(xenbus), errp)) {
xen_backend_set_device(backend, xendev);
goto done;
}
error_prepend(errp, "realization of console device %lu failed: ",
number);
fail:
if (xendev) {
object_unparent(OBJECT(xendev));
}
done:
g_free(fe);
free(type);
free(output);
}
static void xen_console_device_destroy(XenBackendInstance *backend,
Error **errp)
{
ERRP_GUARD();
XenDevice *xendev = xen_backend_get_device(backend);
XenConsole *con = XEN_CONSOLE_DEVICE(xendev);
trace_xen_console_device_destroy(con->dev);
object_unparent(OBJECT(xendev));
}
static const XenBackendInfo xen_console_backend_info = {
.type = "console",
.create = xen_console_device_create,
.destroy = xen_console_device_destroy,
};
static void xen_console_register_backend(void)
{
xen_backend_register(&xen_console_backend_info);
}
xen_backend_init(xen_console_register_backend);