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/*
* Copyright (c) 2021-2025 Oracle and/or its affiliates.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "qemu/cutils.h"
#include "qemu/error-report.h"
#include "qemu/memfd.h"
#include "qapi/error.h"
#include "qapi/type-helpers.h"
#include "io/channel-file.h"
#include "io/channel-socket.h"
#include "block/block-global-state.h"
#include "qemu/main-loop.h"
#include "migration/cpr.h"
#include "migration/qemu-file.h"
#include "migration/migration.h"
#include "migration/misc.h"
#include "migration/vmstate.h"
#include "system/runstate.h"
#include "trace.h"
#define CPR_EXEC_STATE_NAME "QEMU_CPR_EXEC_STATE"
static QEMUFile *qemu_file_new_fd_input(int fd, const char *name)
{
g_autoptr(QIOChannelFile) fioc = qio_channel_file_new_fd(fd);
QIOChannel *ioc = QIO_CHANNEL(fioc);
qio_channel_set_name(ioc, name);
return qemu_file_new_input(ioc);
}
static QEMUFile *qemu_file_new_fd_output(int fd, const char *name)
{
g_autoptr(QIOChannelFile) fioc = qio_channel_file_new_fd(fd);
QIOChannel *ioc = QIO_CHANNEL(fioc);
qio_channel_set_name(ioc, name);
return qemu_file_new_output(ioc);
}
void cpr_exec_persist_state(QEMUFile *f)
{
QIOChannelFile *fioc = QIO_CHANNEL_FILE(qemu_file_get_ioc(f));
int mfd = dup(fioc->fd);
char val[16];
/* Remember mfd in environment for post-exec load */
qemu_clear_cloexec(mfd);
snprintf(val, sizeof(val), "%d", mfd);
g_setenv(CPR_EXEC_STATE_NAME, val, 1);
}
static int cpr_exec_find_state(void)
{
const char *val = g_getenv(CPR_EXEC_STATE_NAME);
int mfd;
assert(val);
g_unsetenv(CPR_EXEC_STATE_NAME);
assert(!qemu_strtoi(val, NULL, 10, &mfd));
return mfd;
}
bool cpr_exec_has_state(void)
{
return g_getenv(CPR_EXEC_STATE_NAME) != NULL;
}
void cpr_exec_unpersist_state(void)
{
int mfd;
const char *val = g_getenv(CPR_EXEC_STATE_NAME);
g_unsetenv(CPR_EXEC_STATE_NAME);
assert(val);
assert(!qemu_strtoi(val, NULL, 10, &mfd));
close(mfd);
}
QEMUFile *cpr_exec_output(Error **errp)
{
int mfd;
#ifdef CONFIG_LINUX
mfd = qemu_memfd_create(CPR_EXEC_STATE_NAME, 0, false, 0, 0, errp);
#else
mfd = -1;
#endif
if (mfd < 0) {
return NULL;
}
return qemu_file_new_fd_output(mfd, CPR_EXEC_STATE_NAME);
}
QEMUFile *cpr_exec_input(Error **errp)
{
int mfd = cpr_exec_find_state();
lseek(mfd, 0, SEEK_SET);
return qemu_file_new_fd_input(mfd, CPR_EXEC_STATE_NAME);
}
static bool preserve_fd(int fd)
{
qemu_clear_cloexec(fd);
return true;
}
static bool unpreserve_fd(int fd)
{
qemu_set_cloexec(fd);
return true;
}
static void cpr_exec_preserve_fds(void)
{
cpr_walk_fd(preserve_fd);
}
void cpr_exec_unpreserve_fds(void)
{
cpr_walk_fd(unpreserve_fd);
}
static void cpr_exec_cb(void *opaque)
{
MigrationState *s = migrate_get_current();
char **argv = strv_from_str_list(s->parameters.cpr_exec_command);
Error *err = NULL;
/*
* Clear the close-on-exec flag for all preserved fd's. We cannot do so
* earlier because they should not persist across miscellaneous fork and
* exec calls that are performed during normal operation.
*/
cpr_exec_preserve_fds();
trace_cpr_exec();
execvp(argv[0], argv);
/*
* exec should only fail if argv[0] is bogus, or has a permissions problem,
* or the system is very short on resources.
*/
g_strfreev(argv);
cpr_exec_unpreserve_fds();
error_setg_errno(&err, errno, "execvp %s failed", argv[0]);
error_report_err(error_copy(err));
migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED);
migrate_set_error(s, err);
/* Note, we can go from state COMPLETED to FAILED */
migration_call_notifiers(s, MIG_EVENT_PRECOPY_FAILED, NULL);
err = NULL;
if (!migration_block_activate(&err)) {
/* error was already reported */
error_free(err);
return;
}
if (runstate_is_live(s->vm_old_state)) {
vm_start();
}
}
static int cpr_exec_notifier(NotifierWithReturn *notifier, MigrationEvent *e,
Error **errp)
{
MigrationState *s = migrate_get_current();
if (e->type == MIG_EVENT_PRECOPY_DONE) {
QEMUBH *cpr_exec_bh = qemu_bh_new(cpr_exec_cb, NULL);
assert(s->state == MIGRATION_STATUS_COMPLETED);
qemu_bh_schedule(cpr_exec_bh);
qemu_notify_event();
} else if (e->type == MIG_EVENT_PRECOPY_FAILED) {
cpr_exec_unpersist_state();
}
return 0;
}
void cpr_exec_init(void)
{
static NotifierWithReturn exec_notifier;
migration_add_notifier_mode(&exec_notifier, cpr_exec_notifier,
MIG_MODE_CPR_EXEC);
}
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