qemu/accel/accel.c
Markus Armbruster 1a3ec8c156 qdev: Fix latent bug with compat_props and onboard devices
Compatibility properties started life as a qdev property thing: we
supported them only for qdev properties, and implemented them with the
machinery backing command line option -global.

Recent commit fa0cb34d22 put them to use (tacitly) with memory
backend objects (subtypes of TYPE_MEMORY_BACKEND).  To make that
possible, we first moved the work of applying them from the -global
machinery into TYPE_DEVICE's .instance_post_init() method
device_post_init(), in commits ea9ce8934c and b66bbee39f, then made
it available to TYPE_MEMORY_BACKEND's .instance_post_init() method
host_memory_backend_post_init() as object_apply_compat_props(), in
commit 1c3994f6d2.

Note the code smell: we now have function name starting with object_
in hw/core/qdev.c.  It has to be there rather than in qom/, because it
calls qdev_get_machine() to find the current accelerator's and
machine's compat_props.

Turns out calling qdev_get_machine() there is problematic.  If we
qdev_create() from a machine's .instance_init() method, we call
device_post_init() and thus qdev_get_machine() before main() can
create "/machine" in QOM.  qdev_get_machine() tries to get it with
container_get(), which "helpfully" creates it as "container" object,
and returns that.  object_apply_compat_props() tries to paper over the
problem by doing nothing when the value of qdev_get_machine() isn't a
TYPE_MACHINE.  But the damage is done already: when main() later
attempts to create the real "/machine", it fails with "attempt to add
duplicate property 'machine' to object (type 'container')", and
aborts.

Since no machine .instance_init() calls qdev_create() so far, the bug
is latent.  But since I want to do that, I get to fix the bug first.

Observe that object_apply_compat_props() doesn't actually need the
MachineState, only its the compat_props member of its MachineClass and
AccelClass.  This permits a simple fix: register MachineClass and
AccelClass compat_props with the object_apply_compat_props() machinery
right after these classes get selected.

This is actually similar to how things worked before commits
ea9ce8934c and b66bbee39f, except we now register much earlier.  The
old code registered them only after the machine's .instance_init()
ran, which would've broken compatibility properties for any devices
created there.

Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190308131445.17502-2-armbru@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
2019-03-11 22:53:44 +01:00

152 lines
4.5 KiB
C

/*
* QEMU System Emulator, accelerator interfaces
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (c) 2014 Red Hat Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "sysemu/accel.h"
#include "hw/boards.h"
#include "sysemu/arch_init.h"
#include "sysemu/sysemu.h"
#include "sysemu/kvm.h"
#include "sysemu/qtest.h"
#include "hw/xen/xen.h"
#include "qom/object.h"
#include "qemu/error-report.h"
#include "qemu/option.h"
#include "qapi/error.h"
static const TypeInfo accel_type = {
.name = TYPE_ACCEL,
.parent = TYPE_OBJECT,
.class_size = sizeof(AccelClass),
.instance_size = sizeof(AccelState),
};
/* Lookup AccelClass from opt_name. Returns NULL if not found */
static AccelClass *accel_find(const char *opt_name)
{
char *class_name = g_strdup_printf(ACCEL_CLASS_NAME("%s"), opt_name);
AccelClass *ac = ACCEL_CLASS(object_class_by_name(class_name));
g_free(class_name);
return ac;
}
static int accel_init_machine(AccelClass *acc, MachineState *ms)
{
ObjectClass *oc = OBJECT_CLASS(acc);
const char *cname = object_class_get_name(oc);
AccelState *accel = ACCEL(object_new(cname));
int ret;
ms->accelerator = accel;
*(acc->allowed) = true;
ret = acc->init_machine(ms);
if (ret < 0) {
ms->accelerator = NULL;
*(acc->allowed) = false;
object_unref(OBJECT(accel));
}
object_set_accelerator_compat_props(acc->compat_props);
return ret;
}
void configure_accelerator(MachineState *ms, const char *progname)
{
const char *accel;
char **accel_list, **tmp;
int ret;
bool accel_initialised = false;
bool init_failed = false;
AccelClass *acc = NULL;
accel = qemu_opt_get(qemu_get_machine_opts(), "accel");
if (accel == NULL) {
/* Select the default accelerator */
int pnlen = strlen(progname);
if (pnlen >= 3 && g_str_equal(&progname[pnlen - 3], "kvm")) {
/* If the program name ends with "kvm", we prefer KVM */
accel = "kvm:tcg";
} else {
#if defined(CONFIG_TCG)
accel = "tcg";
#elif defined(CONFIG_KVM)
accel = "kvm";
#else
error_report("No accelerator selected and"
" no default accelerator available");
exit(1);
#endif
}
}
accel_list = g_strsplit(accel, ":", 0);
for (tmp = accel_list; !accel_initialised && tmp && *tmp; tmp++) {
acc = accel_find(*tmp);
if (!acc) {
continue;
}
if (acc->available && !acc->available()) {
printf("%s not supported for this target\n",
acc->name);
continue;
}
ret = accel_init_machine(acc, ms);
if (ret < 0) {
init_failed = true;
error_report("failed to initialize %s: %s",
acc->name, strerror(-ret));
} else {
accel_initialised = true;
}
}
g_strfreev(accel_list);
if (!accel_initialised) {
if (!init_failed) {
error_report("-machine accel=%s: No accelerator found", accel);
}
exit(1);
}
if (init_failed) {
error_report("Back to %s accelerator", acc->name);
}
}
void accel_setup_post(MachineState *ms)
{
AccelState *accel = ms->accelerator;
AccelClass *acc = ACCEL_GET_CLASS(accel);
if (acc->setup_post) {
acc->setup_post(ms, accel);
}
}
static void register_accel_types(void)
{
type_register_static(&accel_type);
}
type_init(register_accel_types);