Provide migration_precreate_save for saving precreate vmstate across exec.
Create a memfd, save its value in the environment, and serialize state
to it. Reverse the process in migration_precreate_load.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
include/migration/misc.h | 5 ++
migration/meson.build | 1 +
migration/precreate.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 145 insertions(+)
create mode 100644 migration/precreate.c
diff --git a/include/migration/misc.h b/include/migration/misc.h
index c9e200f..cf30351 100644
--- a/include/migration/misc.h
+++ b/include/migration/misc.h
@@ -56,6 +56,11 @@ AnnounceParameters *migrate_announce_params(void);
void dump_vmstate_json_to_file(FILE *out_fp);
+/* migration/precreate.c */
+int migration_precreate_save(Error **errp);
+void migration_precreate_unsave(void);
+int migration_precreate_load(Error **errp);
+
/* migration/migration.c */
void migration_object_init(void);
void migration_shutdown(void);
diff --git a/migration/meson.build b/migration/meson.build
index f76b1ba..50e7cb2 100644
--- a/migration/meson.build
+++ b/migration/meson.build
@@ -26,6 +26,7 @@ system_ss.add(files(
'ram-compress.c',
'options.c',
'postcopy-ram.c',
+ 'precreate.c',
'savevm.c',
'socket.c',
'tls.c',
diff --git a/migration/precreate.c b/migration/precreate.c
new file mode 100644
index 0000000..0bf5e1f
--- /dev/null
+++ b/migration/precreate.c
@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 2022, 2024 Oracle and/or its affiliates.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/cutils.h"
+#include "qemu/memfd.h"
+#include "qapi/error.h"
+#include "io/channel-file.h"
+#include "migration/misc.h"
+#include "migration/qemu-file.h"
+#include "migration/savevm.h"
+
+#define PRECREATE_STATE_NAME "QEMU_PRECREATE_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);
+}
+
+static int memfd_create_named(const char *name, Error **errp)
+{
+ int mfd;
+ char val[16];
+
+ mfd = memfd_create(name, 0);
+ if (mfd < 0) {
+ error_setg_errno(errp, errno, "memfd_create failed");
+ return -1;
+ }
+
+ /* Remember mfd in environment for post-exec load */
+ qemu_clear_cloexec(mfd);
+ snprintf(val, sizeof(val), "%d", mfd);
+ g_setenv(name, val, 1);
+
+ return mfd;
+}
+
+static int memfd_find_named(const char *name, int *mfd_p, Error **errp)
+{
+ const char *val = g_getenv(name);
+
+ if (!val) {
+ *mfd_p = -1;
+ return 0; /* No memfd was created, not an error */
+ }
+ g_unsetenv(name);
+ if (qemu_strtoi(val, NULL, 10, mfd_p)) {
+ error_setg(errp, "Bad %s env value %s", PRECREATE_STATE_NAME, val);
+ return -1;
+ }
+ lseek(*mfd_p, 0, SEEK_SET);
+ return 0;
+}
+
+static void memfd_delete_named(const char *name)
+{
+ int mfd;
+ const char *val = g_getenv(name);
+
+ if (val) {
+ g_unsetenv(name);
+ if (!qemu_strtoi(val, NULL, 10, &mfd)) {
+ close(mfd);
+ }
+ }
+}
+
+static QEMUFile *qemu_file_new_memfd_output(const char *name, Error **errp)
+{
+ int mfd = memfd_create_named(name, errp);
+
+ if (mfd < 0) {
+ return NULL;
+ }
+
+ return qemu_file_new_fd_output(mfd, name);
+}
+
+static QEMUFile *qemu_file_new_memfd_input(const char *name, Error **errp)
+{
+ int ret, mfd;
+
+ ret = memfd_find_named(name, &mfd, errp);
+ if (ret || mfd < 0) {
+ return NULL;
+ }
+
+ return qemu_file_new_fd_input(mfd, name);
+}
+
+int migration_precreate_save(Error **errp)
+{
+ QEMUFile *f = qemu_file_new_memfd_output(PRECREATE_STATE_NAME, errp);
+
+ if (!f) {
+ return -1;
+ } else if (qemu_savevm_precreate_save(f, errp)) {
+ memfd_delete_named(PRECREATE_STATE_NAME);
+ return -1;
+ } else {
+ /* Do not close f, as mfd must remain open. */
+ return 0;
+ }
+}
+
+void migration_precreate_unsave(void)
+{
+ memfd_delete_named(PRECREATE_STATE_NAME);
+}
+
+int migration_precreate_load(Error **errp)
+{
+ int ret;
+ QEMUFile *f = qemu_file_new_memfd_input(PRECREATE_STATE_NAME, errp);
+
+ if (!f) {
+ return -1;
+ }
+ ret = qemu_savevm_precreate_load(f, errp);
+ qemu_fclose(f);
+ g_unsetenv(PRECREATE_STATE_NAME);
+ return ret;
+}
--
1.8.3.1Steve Sistare <steven.sistare@oracle.com> writes:
> Provide migration_precreate_save for saving precreate vmstate across exec.
> Create a memfd, save its value in the environment, and serialize state
> to it. Reverse the process in migration_precreate_load.
>
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
> include/migration/misc.h | 5 ++
> migration/meson.build | 1 +
> migration/precreate.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 145 insertions(+)
> create mode 100644 migration/precreate.c
>
> diff --git a/include/migration/misc.h b/include/migration/misc.h
> index c9e200f..cf30351 100644
> --- a/include/migration/misc.h
> +++ b/include/migration/misc.h
> @@ -56,6 +56,11 @@ AnnounceParameters *migrate_announce_params(void);
>
> void dump_vmstate_json_to_file(FILE *out_fp);
>
> +/* migration/precreate.c */
> +int migration_precreate_save(Error **errp);
> +void migration_precreate_unsave(void);
> +int migration_precreate_load(Error **errp);
> +
> /* migration/migration.c */
> void migration_object_init(void);
> void migration_shutdown(void);
> diff --git a/migration/meson.build b/migration/meson.build
> index f76b1ba..50e7cb2 100644
> --- a/migration/meson.build
> +++ b/migration/meson.build
> @@ -26,6 +26,7 @@ system_ss.add(files(
> 'ram-compress.c',
> 'options.c',
> 'postcopy-ram.c',
> + 'precreate.c',
> 'savevm.c',
> 'socket.c',
> 'tls.c',
> diff --git a/migration/precreate.c b/migration/precreate.c
> new file mode 100644
> index 0000000..0bf5e1f
> --- /dev/null
> +++ b/migration/precreate.c
> @@ -0,0 +1,139 @@
> +/*
> + * Copyright (c) 2022, 2024 Oracle and/or its affiliates.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/cutils.h"
> +#include "qemu/memfd.h"
> +#include "qapi/error.h"
> +#include "io/channel-file.h"
> +#include "migration/misc.h"
> +#include "migration/qemu-file.h"
> +#include "migration/savevm.h"
> +
> +#define PRECREATE_STATE_NAME "QEMU_PRECREATE_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);
> +}
> +
> +static int memfd_create_named(const char *name, Error **errp)
> +{
> + int mfd;
> + char val[16];
> +
> + mfd = memfd_create(name, 0);
> + if (mfd < 0) {
> + error_setg_errno(errp, errno, "memfd_create failed");
> + return -1;
> + }
> +
> + /* Remember mfd in environment for post-exec load */
> + qemu_clear_cloexec(mfd);
> + snprintf(val, sizeof(val), "%d", mfd);
> + g_setenv(name, val, 1);
> +
> + return mfd;
> +}
> +
> +static int memfd_find_named(const char *name, int *mfd_p, Error **errp)
> +{
> + const char *val = g_getenv(name);
> +
> + if (!val) {
> + *mfd_p = -1;
> + return 0; /* No memfd was created, not an error */
> + }
> + g_unsetenv(name);
> + if (qemu_strtoi(val, NULL, 10, mfd_p)) {
> + error_setg(errp, "Bad %s env value %s", PRECREATE_STATE_NAME, val);
> + return -1;
> + }
> + lseek(*mfd_p, 0, SEEK_SET);
> + return 0;
> +}
> +
> +static void memfd_delete_named(const char *name)
> +{
> + int mfd;
> + const char *val = g_getenv(name);
> +
> + if (val) {
> + g_unsetenv(name);
> + if (!qemu_strtoi(val, NULL, 10, &mfd)) {
> + close(mfd);
> + }
> + }
> +}
> +
> +static QEMUFile *qemu_file_new_memfd_output(const char *name, Error **errp)
> +{
> + int mfd = memfd_create_named(name, errp);
> +
> + if (mfd < 0) {
> + return NULL;
> + }
> +
> + return qemu_file_new_fd_output(mfd, name);
> +}
> +
> +static QEMUFile *qemu_file_new_memfd_input(const char *name, Error **errp)
> +{
> + int ret, mfd;
> +
> + ret = memfd_find_named(name, &mfd, errp);
> + if (ret || mfd < 0) {
> + return NULL;
> + }
> +
> + return qemu_file_new_fd_input(mfd, name);
> +}
> +
> +int migration_precreate_save(Error **errp)
> +{
> + QEMUFile *f = qemu_file_new_memfd_output(PRECREATE_STATE_NAME, errp);
> +
> + if (!f) {
> + return -1;
> + } else if (qemu_savevm_precreate_save(f, errp)) {
> + memfd_delete_named(PRECREATE_STATE_NAME);
> + return -1;
> + } else {
> + /* Do not close f, as mfd must remain open. */
> + return 0;
> + }
> +}
> +
> +void migration_precreate_unsave(void)
> +{
> + memfd_delete_named(PRECREATE_STATE_NAME);
> +}
> +
> +int migration_precreate_load(Error **errp)
> +{
> + int ret;
> + QEMUFile *f = qemu_file_new_memfd_input(PRECREATE_STATE_NAME, errp);
Can we avoid the QEMUFile? I don't see it being exported from this file.
> +
> + if (!f) {
> + return -1;
> + }
> + ret = qemu_savevm_precreate_load(f, errp);
> + qemu_fclose(f);
> + g_unsetenv(PRECREATE_STATE_NAME);
> + return ret;
> +}
On 5/6/2024 7:34 PM, Fabiano Rosas wrote:
> Steve Sistare <steven.sistare@oracle.com> writes:
>
>> Provide migration_precreate_save for saving precreate vmstate across exec.
>> Create a memfd, save its value in the environment, and serialize state
>> to it. Reverse the process in migration_precreate_load.
>>
>> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
>> ---
>> include/migration/misc.h | 5 ++
>> migration/meson.build | 1 +
>> migration/precreate.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 145 insertions(+)
>> create mode 100644 migration/precreate.c
>>
>> diff --git a/include/migration/misc.h b/include/migration/misc.h
>> index c9e200f..cf30351 100644
>> --- a/include/migration/misc.h
>> +++ b/include/migration/misc.h
>> @@ -56,6 +56,11 @@ AnnounceParameters *migrate_announce_params(void);
>>
>> void dump_vmstate_json_to_file(FILE *out_fp);
>>
>> +/* migration/precreate.c */
>> +int migration_precreate_save(Error **errp);
>> +void migration_precreate_unsave(void);
>> +int migration_precreate_load(Error **errp);
>> +
>> /* migration/migration.c */
>> void migration_object_init(void);
>> void migration_shutdown(void);
>> diff --git a/migration/meson.build b/migration/meson.build
>> index f76b1ba..50e7cb2 100644
>> --- a/migration/meson.build
>> +++ b/migration/meson.build
>> @@ -26,6 +26,7 @@ system_ss.add(files(
>> 'ram-compress.c',
>> 'options.c',
>> 'postcopy-ram.c',
>> + 'precreate.c',
>> 'savevm.c',
>> 'socket.c',
>> 'tls.c',
>> diff --git a/migration/precreate.c b/migration/precreate.c
>> new file mode 100644
>> index 0000000..0bf5e1f
>> --- /dev/null
>> +++ b/migration/precreate.c
>> @@ -0,0 +1,139 @@
>> +/*
>> + * Copyright (c) 2022, 2024 Oracle and/or its affiliates.
>> + *
>> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
>> + * See the COPYING file in the top-level directory.
>> + */
>> +
>> +#include "qemu/osdep.h"
>> +#include "qemu/cutils.h"
>> +#include "qemu/memfd.h"
>> +#include "qapi/error.h"
>> +#include "io/channel-file.h"
>> +#include "migration/misc.h"
>> +#include "migration/qemu-file.h"
>> +#include "migration/savevm.h"
>> +
>> +#define PRECREATE_STATE_NAME "QEMU_PRECREATE_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);
>> +}
>> +
>> +static int memfd_create_named(const char *name, Error **errp)
>> +{
>> + int mfd;
>> + char val[16];
>> +
>> + mfd = memfd_create(name, 0);
>> + if (mfd < 0) {
>> + error_setg_errno(errp, errno, "memfd_create failed");
>> + return -1;
>> + }
>> +
>> + /* Remember mfd in environment for post-exec load */
>> + qemu_clear_cloexec(mfd);
>> + snprintf(val, sizeof(val), "%d", mfd);
>> + g_setenv(name, val, 1);
>> +
>> + return mfd;
>> +}
>> +
>> +static int memfd_find_named(const char *name, int *mfd_p, Error **errp)
>> +{
>> + const char *val = g_getenv(name);
>> +
>> + if (!val) {
>> + *mfd_p = -1;
>> + return 0; /* No memfd was created, not an error */
>> + }
>> + g_unsetenv(name);
>> + if (qemu_strtoi(val, NULL, 10, mfd_p)) {
>> + error_setg(errp, "Bad %s env value %s", PRECREATE_STATE_NAME, val);
>> + return -1;
>> + }
>> + lseek(*mfd_p, 0, SEEK_SET);
>> + return 0;
>> +}
>> +
>> +static void memfd_delete_named(const char *name)
>> +{
>> + int mfd;
>> + const char *val = g_getenv(name);
>> +
>> + if (val) {
>> + g_unsetenv(name);
>> + if (!qemu_strtoi(val, NULL, 10, &mfd)) {
>> + close(mfd);
>> + }
>> + }
>> +}
>> +
>> +static QEMUFile *qemu_file_new_memfd_output(const char *name, Error **errp)
>> +{
>> + int mfd = memfd_create_named(name, errp);
>> +
>> + if (mfd < 0) {
>> + return NULL;
>> + }
>> +
>> + return qemu_file_new_fd_output(mfd, name);
>> +}
>> +
>> +static QEMUFile *qemu_file_new_memfd_input(const char *name, Error **errp)
>> +{
>> + int ret, mfd;
>> +
>> + ret = memfd_find_named(name, &mfd, errp);
>> + if (ret || mfd < 0) {
>> + return NULL;
>> + }
>> +
>> + return qemu_file_new_fd_input(mfd, name);
>> +}
>> +
>> +int migration_precreate_save(Error **errp)
>> +{
>> + QEMUFile *f = qemu_file_new_memfd_output(PRECREATE_STATE_NAME, errp);
>> +
>> + if (!f) {
>> + return -1;
>> + } else if (qemu_savevm_precreate_save(f, errp)) {
>> + memfd_delete_named(PRECREATE_STATE_NAME);
>> + return -1;
>> + } else {
>> + /* Do not close f, as mfd must remain open. */
>> + return 0;
>> + }
>> +}
>> +
>> +void migration_precreate_unsave(void)
>> +{
>> + memfd_delete_named(PRECREATE_STATE_NAME);
>> +}
>> +
>> +int migration_precreate_load(Error **errp)
>> +{
>> + int ret;
>> + QEMUFile *f = qemu_file_new_memfd_input(PRECREATE_STATE_NAME, errp);
>
> Can we avoid the QEMUFile? I don't see it being exported from this file.
It is not exported, but within this file, it is the basis for all read and
write operations, via the existing functions qemu_file_new_input() and
qemu_file_new_output()
- Steve
>> +
>> + if (!f) {
>> + return -1;
>> + }
>> + ret = qemu_savevm_precreate_load(f, errp);
>> + qemu_fclose(f);
>> + g_unsetenv(PRECREATE_STATE_NAME);
>> + return ret;
>> +}
Steven Sistare <steven.sistare@oracle.com> writes:
> On 5/6/2024 7:34 PM, Fabiano Rosas wrote:
>> Steve Sistare <steven.sistare@oracle.com> writes:
>>
>>> Provide migration_precreate_save for saving precreate vmstate across exec.
>>> Create a memfd, save its value in the environment, and serialize state
>>> to it. Reverse the process in migration_precreate_load.
>>>
>>> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
>>> ---
>>> include/migration/misc.h | 5 ++
>>> migration/meson.build | 1 +
>>> migration/precreate.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++
>>> 3 files changed, 145 insertions(+)
>>> create mode 100644 migration/precreate.c
>>>
>>> diff --git a/include/migration/misc.h b/include/migration/misc.h
>>> index c9e200f..cf30351 100644
>>> --- a/include/migration/misc.h
>>> +++ b/include/migration/misc.h
>>> @@ -56,6 +56,11 @@ AnnounceParameters *migrate_announce_params(void);
>>>
>>> void dump_vmstate_json_to_file(FILE *out_fp);
>>>
>>> +/* migration/precreate.c */
>>> +int migration_precreate_save(Error **errp);
>>> +void migration_precreate_unsave(void);
>>> +int migration_precreate_load(Error **errp);
>>> +
>>> /* migration/migration.c */
>>> void migration_object_init(void);
>>> void migration_shutdown(void);
>>> diff --git a/migration/meson.build b/migration/meson.build
>>> index f76b1ba..50e7cb2 100644
>>> --- a/migration/meson.build
>>> +++ b/migration/meson.build
>>> @@ -26,6 +26,7 @@ system_ss.add(files(
>>> 'ram-compress.c',
>>> 'options.c',
>>> 'postcopy-ram.c',
>>> + 'precreate.c',
>>> 'savevm.c',
>>> 'socket.c',
>>> 'tls.c',
>>> diff --git a/migration/precreate.c b/migration/precreate.c
>>> new file mode 100644
>>> index 0000000..0bf5e1f
>>> --- /dev/null
>>> +++ b/migration/precreate.c
>>> @@ -0,0 +1,139 @@
>>> +/*
>>> + * Copyright (c) 2022, 2024 Oracle and/or its affiliates.
>>> + *
>>> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
>>> + * See the COPYING file in the top-level directory.
>>> + */
>>> +
>>> +#include "qemu/osdep.h"
>>> +#include "qemu/cutils.h"
>>> +#include "qemu/memfd.h"
>>> +#include "qapi/error.h"
>>> +#include "io/channel-file.h"
>>> +#include "migration/misc.h"
>>> +#include "migration/qemu-file.h"
>>> +#include "migration/savevm.h"
>>> +
>>> +#define PRECREATE_STATE_NAME "QEMU_PRECREATE_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);
>>> +}
>>> +
>>> +static int memfd_create_named(const char *name, Error **errp)
>>> +{
>>> + int mfd;
>>> + char val[16];
>>> +
>>> + mfd = memfd_create(name, 0);
>>> + if (mfd < 0) {
>>> + error_setg_errno(errp, errno, "memfd_create failed");
>>> + return -1;
>>> + }
>>> +
>>> + /* Remember mfd in environment for post-exec load */
>>> + qemu_clear_cloexec(mfd);
>>> + snprintf(val, sizeof(val), "%d", mfd);
>>> + g_setenv(name, val, 1);
>>> +
>>> + return mfd;
>>> +}
>>> +
>>> +static int memfd_find_named(const char *name, int *mfd_p, Error **errp)
>>> +{
>>> + const char *val = g_getenv(name);
>>> +
>>> + if (!val) {
>>> + *mfd_p = -1;
>>> + return 0; /* No memfd was created, not an error */
>>> + }
>>> + g_unsetenv(name);
>>> + if (qemu_strtoi(val, NULL, 10, mfd_p)) {
>>> + error_setg(errp, "Bad %s env value %s", PRECREATE_STATE_NAME, val);
>>> + return -1;
>>> + }
>>> + lseek(*mfd_p, 0, SEEK_SET);
>>> + return 0;
>>> +}
>>> +
>>> +static void memfd_delete_named(const char *name)
>>> +{
>>> + int mfd;
>>> + const char *val = g_getenv(name);
>>> +
>>> + if (val) {
>>> + g_unsetenv(name);
>>> + if (!qemu_strtoi(val, NULL, 10, &mfd)) {
>>> + close(mfd);
>>> + }
>>> + }
>>> +}
>>> +
>>> +static QEMUFile *qemu_file_new_memfd_output(const char *name, Error **errp)
>>> +{
>>> + int mfd = memfd_create_named(name, errp);
>>> +
>>> + if (mfd < 0) {
>>> + return NULL;
>>> + }
>>> +
>>> + return qemu_file_new_fd_output(mfd, name);
>>> +}
>>> +
>>> +static QEMUFile *qemu_file_new_memfd_input(const char *name, Error **errp)
>>> +{
>>> + int ret, mfd;
>>> +
>>> + ret = memfd_find_named(name, &mfd, errp);
>>> + if (ret || mfd < 0) {
>>> + return NULL;
>>> + }
>>> +
>>> + return qemu_file_new_fd_input(mfd, name);
>>> +}
>>> +
>>> +int migration_precreate_save(Error **errp)
>>> +{
>>> + QEMUFile *f = qemu_file_new_memfd_output(PRECREATE_STATE_NAME, errp);
>>> +
>>> + if (!f) {
>>> + return -1;
>>> + } else if (qemu_savevm_precreate_save(f, errp)) {
>>> + memfd_delete_named(PRECREATE_STATE_NAME);
>>> + return -1;
>>> + } else {
>>> + /* Do not close f, as mfd must remain open. */
>>> + return 0;
>>> + }
>>> +}
>>> +
>>> +void migration_precreate_unsave(void)
>>> +{
>>> + memfd_delete_named(PRECREATE_STATE_NAME);
>>> +}
>>> +
>>> +int migration_precreate_load(Error **errp)
>>> +{
>>> + int ret;
>>> + QEMUFile *f = qemu_file_new_memfd_input(PRECREATE_STATE_NAME, errp);
>>
>> Can we avoid the QEMUFile? I don't see it being exported from this file.
>
> It is not exported, but within this file, it is the basis for all read and
> write operations, via the existing functions qemu_file_new_input() and
> qemu_file_new_output()
Right, that's the easy part, we could just use the QIOChannel
directly. But I missed the fact that you also need to interop with the
existing code that needs the QEMUFile.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
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