diff options
Diffstat (limited to 'migration/cpr-exec.c')
| -rw-r--r-- | migration/cpr-exec.c | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/migration/cpr-exec.c b/migration/cpr-exec.c new file mode 100644 index 0000000..d57714b --- /dev/null +++ b/migration/cpr-exec.c @@ -0,0 +1,194 @@ +/* + * 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); +} |