efc6587313
To preserve CPR state across exec, create a QEMUFile based on a memfd, and keep the memfd open across exec. Save the value of the memfd in an environment variable so post-exec QEMU can find it. These new functions are called in a subsequent patch. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Link: https://lore.kernel.org/r/1759332851-370353-6-git-send-email-steven.sistare@oracle.com [peterx: fix build for Windows] Signed-off-by: Peter Xu <peterx@redhat.com>
99 lines
2.3 KiB
C
99 lines
2.3 KiB
C
/*
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* Copyright (c) 2021-2025 Oracle and/or its affiliates.
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "qemu/osdep.h"
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#include "qemu/cutils.h"
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#include "qemu/memfd.h"
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#include "qapi/error.h"
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#include "io/channel-file.h"
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#include "io/channel-socket.h"
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#include "migration/cpr.h"
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#include "migration/qemu-file.h"
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#include "migration/misc.h"
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#include "migration/vmstate.h"
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#include "system/runstate.h"
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#define CPR_EXEC_STATE_NAME "QEMU_CPR_EXEC_STATE"
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static QEMUFile *qemu_file_new_fd_input(int fd, const char *name)
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{
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g_autoptr(QIOChannelFile) fioc = qio_channel_file_new_fd(fd);
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QIOChannel *ioc = QIO_CHANNEL(fioc);
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qio_channel_set_name(ioc, name);
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return qemu_file_new_input(ioc);
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}
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static QEMUFile *qemu_file_new_fd_output(int fd, const char *name)
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{
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g_autoptr(QIOChannelFile) fioc = qio_channel_file_new_fd(fd);
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QIOChannel *ioc = QIO_CHANNEL(fioc);
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qio_channel_set_name(ioc, name);
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return qemu_file_new_output(ioc);
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}
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void cpr_exec_persist_state(QEMUFile *f)
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{
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QIOChannelFile *fioc = QIO_CHANNEL_FILE(qemu_file_get_ioc(f));
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int mfd = dup(fioc->fd);
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char val[16];
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/* Remember mfd in environment for post-exec load */
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qemu_clear_cloexec(mfd);
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snprintf(val, sizeof(val), "%d", mfd);
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g_setenv(CPR_EXEC_STATE_NAME, val, 1);
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}
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static int cpr_exec_find_state(void)
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{
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const char *val = g_getenv(CPR_EXEC_STATE_NAME);
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int mfd;
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assert(val);
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g_unsetenv(CPR_EXEC_STATE_NAME);
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assert(!qemu_strtoi(val, NULL, 10, &mfd));
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return mfd;
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}
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bool cpr_exec_has_state(void)
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{
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return g_getenv(CPR_EXEC_STATE_NAME) != NULL;
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}
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void cpr_exec_unpersist_state(void)
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{
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int mfd;
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const char *val = g_getenv(CPR_EXEC_STATE_NAME);
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g_unsetenv(CPR_EXEC_STATE_NAME);
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assert(val);
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assert(!qemu_strtoi(val, NULL, 10, &mfd));
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close(mfd);
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}
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QEMUFile *cpr_exec_output(Error **errp)
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{
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int mfd;
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#ifdef CONFIG_LINUX
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mfd = qemu_memfd_create(CPR_EXEC_STATE_NAME, 0, false, 0, 0, errp);
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#else
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mfd = -1;
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#endif
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if (mfd < 0) {
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return NULL;
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}
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return qemu_file_new_fd_output(mfd, CPR_EXEC_STATE_NAME);
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}
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QEMUFile *cpr_exec_input(Error **errp)
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{
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int mfd = cpr_exec_find_state();
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lseek(mfd, 0, SEEK_SET);
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return qemu_file_new_fd_input(mfd, CPR_EXEC_STATE_NAME);
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}
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