From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
Let's introduce vmstate_{load,save}_field() helpers, they will
be used in next patches to support fully-dynamic arrays with NULLs.
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
---
include/migration/vmstate.h | 4 ++
migration/vmstate.c | 84 +++++++++++++++++++++++--------------
2 files changed, 56 insertions(+), 32 deletions(-)
diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 62c2abd0c49..5d7dfe70643 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -1240,8 +1240,12 @@ extern const VMStateInfo vmstate_info_qlist;
.flags = VMS_END, \
}
+int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
+ const VMStateField *field, Error **errp);
int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
void *opaque, int version_id, Error **errp);
+int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
+ const VMStateField *field, JSONWriter *vmdesc, Error **errp);
int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
void *opaque, JSONWriter *vmdesc, Error **errp);
int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
diff --git a/migration/vmstate.c b/migration/vmstate.c
index 4d28364f7ba..8d192bcaa27 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -131,6 +131,32 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
}
}
+int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
+ const VMStateField *field, Error **errp)
+{
+ int ret = 0;
+
+ if (field->flags & VMS_STRUCT) {
+ ret = vmstate_load_state(f, field->vmsd, pv,
+ field->vmsd->version_id,
+ errp);
+ } else if (field->flags & VMS_VSTRUCT) {
+ ret = vmstate_load_state(f, field->vmsd, pv,
+ field->struct_version_id,
+ errp);
+ } else {
+ ret = field->info->get(f, pv, size, field);
+ if (ret < 0) {
+ error_setg(errp,
+ "Failed to load element of type %s for %s: "
+ "%d", field->info->name,
+ field->name, ret);
+ }
+ }
+
+ return ret;
+}
+
int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
void *opaque, int version_id, Error **errp)
{
@@ -203,24 +229,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
inner_field = field;
}
- if (inner_field->flags & VMS_STRUCT) {
- ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
- inner_field->vmsd->version_id,
- errp);
- } else if (inner_field->flags & VMS_VSTRUCT) {
- ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
- inner_field->struct_version_id,
- errp);
- } else {
- ret = inner_field->info->get(f, curr_elem, size,
- inner_field);
- if (ret < 0) {
- error_setg(errp,
- "Failed to load element of type %s for %s: "
- "%d", inner_field->info->name,
- inner_field->name, ret);
- }
- }
+ ret = vmstate_load_field(f, curr_elem, size, inner_field, errp);
/* If we used a fake temp field.. free it now */
if (inner_field != field) {
@@ -427,6 +436,29 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
}
+int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
+ const VMStateField *field, JSONWriter *vmdesc, Error **errp)
+{
+ int ret = 0;
+
+ if (field->flags & VMS_STRUCT) {
+ ret = vmstate_save_state(f, field->vmsd, pv, vmdesc, errp);
+ } else if (field->flags & VMS_VSTRUCT) {
+ ret = vmstate_save_state_v(f, field->vmsd, pv, vmdesc,
+ field->struct_version_id, errp);
+ } else {
+ ret = field->info->put(f, pv, size, field, vmdesc);
+ if (ret < 0) {
+ error_setg(errp,
+ "Failed to save element of type %s for %s: "
+ "%d", field->info->name,
+ field->name, ret);
+ }
+ }
+
+ return ret;
+}
+
int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
{
@@ -528,19 +560,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field,
i, max_elems);
- if (inner_field->flags & VMS_STRUCT) {
- ret = vmstate_save_state(f, inner_field->vmsd,
- curr_elem, vmdesc_loop, errp);
- } else if (inner_field->flags & VMS_VSTRUCT) {
- ret = vmstate_save_state_v(f, inner_field->vmsd,
- curr_elem, vmdesc_loop,
- inner_field->struct_version_id,
- errp);
- } else {
- ret = inner_field->info->put(f, curr_elem, size,
- inner_field, vmdesc_loop);
- }
-
+ ret = vmstate_save_field(f, curr_elem, size, inner_field, vmdesc_loop, errp);
written_bytes = qemu_file_transferred(f) - old_offset;
vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field,
written_bytes);
@@ -551,7 +571,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
}
if (ret) {
- error_setg(errp, "Save of field %s/%s failed",
+ error_prepend(errp, "Save of field %s/%s failed: ",
vmsd->name, field->name);
if (vmsd->post_save) {
vmsd->post_save(opaque);
--
2.47.3On Fri, Mar 13, 2026 at 03:12:14PM +0100, Alexander Mikhalitsyn wrote:
> From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
>
> Let's introduce vmstate_{load,save}_field() helpers, they will
> be used in next patches to support fully-dynamic arrays with NULLs.
>
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
Feel free to rebase to Vladimir's series here, Fabiano already queued it:
https://lore.kernel.org/all/20260304212303.667141-11-vsementsov@yandex-team.ru/#t
These codes weren't touched that frequent, it's interesting to see such
coinsidence happens. :)
> ---
> include/migration/vmstate.h | 4 ++
> migration/vmstate.c | 84 +++++++++++++++++++++++--------------
> 2 files changed, 56 insertions(+), 32 deletions(-)
>
> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> index 62c2abd0c49..5d7dfe70643 100644
> --- a/include/migration/vmstate.h
> +++ b/include/migration/vmstate.h
> @@ -1240,8 +1240,12 @@ extern const VMStateInfo vmstate_info_qlist;
> .flags = VMS_END, \
> }
>
> +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> + const VMStateField *field, Error **errp);
> int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> void *opaque, int version_id, Error **errp);
> +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> + const VMStateField *field, JSONWriter *vmdesc, Error **errp);
> int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> void *opaque, JSONWriter *vmdesc, Error **errp);
> int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> diff --git a/migration/vmstate.c b/migration/vmstate.c
> index 4d28364f7ba..8d192bcaa27 100644
> --- a/migration/vmstate.c
> +++ b/migration/vmstate.c
> @@ -131,6 +131,32 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
> }
> }
>
> +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> + const VMStateField *field, Error **errp)
> +{
> + int ret = 0;
> +
> + if (field->flags & VMS_STRUCT) {
> + ret = vmstate_load_state(f, field->vmsd, pv,
> + field->vmsd->version_id,
> + errp);
> + } else if (field->flags & VMS_VSTRUCT) {
> + ret = vmstate_load_state(f, field->vmsd, pv,
> + field->struct_version_id,
> + errp);
> + } else {
> + ret = field->info->get(f, pv, size, field);
> + if (ret < 0) {
> + error_setg(errp,
> + "Failed to load element of type %s for %s: "
> + "%d", field->info->name,
> + field->name, ret);
> + }
> + }
> +
> + return ret;
> +}
> +
> int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> void *opaque, int version_id, Error **errp)
> {
> @@ -203,24 +229,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> inner_field = field;
> }
>
> - if (inner_field->flags & VMS_STRUCT) {
> - ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> - inner_field->vmsd->version_id,
> - errp);
> - } else if (inner_field->flags & VMS_VSTRUCT) {
> - ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> - inner_field->struct_version_id,
> - errp);
> - } else {
> - ret = inner_field->info->get(f, curr_elem, size,
> - inner_field);
> - if (ret < 0) {
> - error_setg(errp,
> - "Failed to load element of type %s for %s: "
> - "%d", inner_field->info->name,
> - inner_field->name, ret);
> - }
> - }
> + ret = vmstate_load_field(f, curr_elem, size, inner_field, errp);
>
> /* If we used a fake temp field.. free it now */
> if (inner_field != field) {
> @@ -427,6 +436,29 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
> }
>
> +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> + const VMStateField *field, JSONWriter *vmdesc, Error **errp)
> +{
> + int ret = 0;
> +
> + if (field->flags & VMS_STRUCT) {
> + ret = vmstate_save_state(f, field->vmsd, pv, vmdesc, errp);
> + } else if (field->flags & VMS_VSTRUCT) {
> + ret = vmstate_save_state_v(f, field->vmsd, pv, vmdesc,
> + field->struct_version_id, errp);
> + } else {
> + ret = field->info->put(f, pv, size, field, vmdesc);
> + if (ret < 0) {
> + error_setg(errp,
> + "Failed to save element of type %s for %s: "
> + "%d", field->info->name,
> + field->name, ret);
> + }
> + }
> +
> + return ret;
> +}
> +
> int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
> {
> @@ -528,19 +560,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field,
> i, max_elems);
>
> - if (inner_field->flags & VMS_STRUCT) {
> - ret = vmstate_save_state(f, inner_field->vmsd,
> - curr_elem, vmdesc_loop, errp);
> - } else if (inner_field->flags & VMS_VSTRUCT) {
> - ret = vmstate_save_state_v(f, inner_field->vmsd,
> - curr_elem, vmdesc_loop,
> - inner_field->struct_version_id,
> - errp);
> - } else {
> - ret = inner_field->info->put(f, curr_elem, size,
> - inner_field, vmdesc_loop);
> - }
> -
> + ret = vmstate_save_field(f, curr_elem, size, inner_field, vmdesc_loop, errp);
> written_bytes = qemu_file_transferred(f) - old_offset;
> vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field,
> written_bytes);
> @@ -551,7 +571,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> }
>
> if (ret) {
> - error_setg(errp, "Save of field %s/%s failed",
> + error_prepend(errp, "Save of field %s/%s failed: ",
> vmsd->name, field->name);
> if (vmsd->post_save) {
> vmsd->post_save(opaque);
> --
> 2.47.3
>
--
Peter Xu
Am Fr., 13. März 2026 um 17:27 Uhr schrieb Peter Xu <peterx@redhat.com>:
>
> On Fri, Mar 13, 2026 at 03:12:14PM +0100, Alexander Mikhalitsyn wrote:
> > From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
> >
> > Let's introduce vmstate_{load,save}_field() helpers, they will
> > be used in next patches to support fully-dynamic arrays with NULLs.
> >
> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
>
Hi Peter,
> Feel free to rebase to Vladimir's series here, Fabiano already queued it:
>
> https://lore.kernel.org/all/20260304212303.667141-11-vsementsov@yandex-team.ru/#t
I've tried, but I can't see it anywhere
https://gitlab.com/farosas/qemu/-/commits/migration-next
doesn't contain it. As of now, last commit is
472f455cfbb0c5f84a7d48228d5226eaf6c7a61b.
Also, patchew tells that that series has conflicts with master:
https://patchew.org/QEMU/20260304212303.667141-1-vsementsov@yandex-team.ru/
Should I manually download mbox, apply/resolve conflicts with master,
then rebase my stuff and resend?
Kind regards,
Alex
>
> These codes weren't touched that frequent, it's interesting to see such
> coinsidence happens. :)
>
> > ---
> > include/migration/vmstate.h | 4 ++
> > migration/vmstate.c | 84 +++++++++++++++++++++++--------------
> > 2 files changed, 56 insertions(+), 32 deletions(-)
> >
> > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> > index 62c2abd0c49..5d7dfe70643 100644
> > --- a/include/migration/vmstate.h
> > +++ b/include/migration/vmstate.h
> > @@ -1240,8 +1240,12 @@ extern const VMStateInfo vmstate_info_qlist;
> > .flags = VMS_END, \
> > }
> >
> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> > + const VMStateField *field, Error **errp);
> > int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> > void *opaque, int version_id, Error **errp);
> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> > + const VMStateField *field, JSONWriter *vmdesc, Error **errp);
> > int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> > void *opaque, JSONWriter *vmdesc, Error **errp);
> > int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> > diff --git a/migration/vmstate.c b/migration/vmstate.c
> > index 4d28364f7ba..8d192bcaa27 100644
> > --- a/migration/vmstate.c
> > +++ b/migration/vmstate.c
> > @@ -131,6 +131,32 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
> > }
> > }
> >
> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> > + const VMStateField *field, Error **errp)
> > +{
> > + int ret = 0;
> > +
> > + if (field->flags & VMS_STRUCT) {
> > + ret = vmstate_load_state(f, field->vmsd, pv,
> > + field->vmsd->version_id,
> > + errp);
> > + } else if (field->flags & VMS_VSTRUCT) {
> > + ret = vmstate_load_state(f, field->vmsd, pv,
> > + field->struct_version_id,
> > + errp);
> > + } else {
> > + ret = field->info->get(f, pv, size, field);
> > + if (ret < 0) {
> > + error_setg(errp,
> > + "Failed to load element of type %s for %s: "
> > + "%d", field->info->name,
> > + field->name, ret);
> > + }
> > + }
> > +
> > + return ret;
> > +}
> > +
> > int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> > void *opaque, int version_id, Error **errp)
> > {
> > @@ -203,24 +229,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> > inner_field = field;
> > }
> >
> > - if (inner_field->flags & VMS_STRUCT) {
> > - ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> > - inner_field->vmsd->version_id,
> > - errp);
> > - } else if (inner_field->flags & VMS_VSTRUCT) {
> > - ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> > - inner_field->struct_version_id,
> > - errp);
> > - } else {
> > - ret = inner_field->info->get(f, curr_elem, size,
> > - inner_field);
> > - if (ret < 0) {
> > - error_setg(errp,
> > - "Failed to load element of type %s for %s: "
> > - "%d", inner_field->info->name,
> > - inner_field->name, ret);
> > - }
> > - }
> > + ret = vmstate_load_field(f, curr_elem, size, inner_field, errp);
> >
> > /* If we used a fake temp field.. free it now */
> > if (inner_field != field) {
> > @@ -427,6 +436,29 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> > return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
> > }
> >
> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> > + const VMStateField *field, JSONWriter *vmdesc, Error **errp)
> > +{
> > + int ret = 0;
> > +
> > + if (field->flags & VMS_STRUCT) {
> > + ret = vmstate_save_state(f, field->vmsd, pv, vmdesc, errp);
> > + } else if (field->flags & VMS_VSTRUCT) {
> > + ret = vmstate_save_state_v(f, field->vmsd, pv, vmdesc,
> > + field->struct_version_id, errp);
> > + } else {
> > + ret = field->info->put(f, pv, size, field, vmdesc);
> > + if (ret < 0) {
> > + error_setg(errp,
> > + "Failed to save element of type %s for %s: "
> > + "%d", field->info->name,
> > + field->name, ret);
> > + }
> > + }
> > +
> > + return ret;
> > +}
> > +
> > int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> > void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
> > {
> > @@ -528,19 +560,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> > vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field,
> > i, max_elems);
> >
> > - if (inner_field->flags & VMS_STRUCT) {
> > - ret = vmstate_save_state(f, inner_field->vmsd,
> > - curr_elem, vmdesc_loop, errp);
> > - } else if (inner_field->flags & VMS_VSTRUCT) {
> > - ret = vmstate_save_state_v(f, inner_field->vmsd,
> > - curr_elem, vmdesc_loop,
> > - inner_field->struct_version_id,
> > - errp);
> > - } else {
> > - ret = inner_field->info->put(f, curr_elem, size,
> > - inner_field, vmdesc_loop);
> > - }
> > -
> > + ret = vmstate_save_field(f, curr_elem, size, inner_field, vmdesc_loop, errp);
> > written_bytes = qemu_file_transferred(f) - old_offset;
> > vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field,
> > written_bytes);
> > @@ -551,7 +571,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> > }
> >
> > if (ret) {
> > - error_setg(errp, "Save of field %s/%s failed",
> > + error_prepend(errp, "Save of field %s/%s failed: ",
> > vmsd->name, field->name);
> > if (vmsd->post_save) {
> > vmsd->post_save(opaque);
> > --
> > 2.47.3
> >
>
> --
> Peter Xu
>
Alexander Mikhalitsyn via qemu development <qemu-devel@nongnu.org>
writes:
> Am Fr., 13. März 2026 um 17:27 Uhr schrieb Peter Xu <peterx@redhat.com>:
>>
>> On Fri, Mar 13, 2026 at 03:12:14PM +0100, Alexander Mikhalitsyn wrote:
>> > From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
>> >
>> > Let's introduce vmstate_{load,save}_field() helpers, they will
>> > be used in next patches to support fully-dynamic arrays with NULLs.
>> >
>> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
>>
>
> Hi Peter,
>
>> Feel free to rebase to Vladimir's series here, Fabiano already queued it:
>>
>> https://lore.kernel.org/all/20260304212303.667141-11-vsementsov@yandex-team.ru/#t
>
> I've tried, but I can't see it anywhere
> https://gitlab.com/farosas/qemu/-/commits/migration-next
> doesn't contain it. As of now, last commit is
> 472f455cfbb0c5f84a7d48228d5226eaf6c7a61b.
>
I think we usually just take the patches from the list and apply
directly instead of taking any branch*. I don't keep migration-next
stable.
I pushed migration-staging which you can use. It'll collect the patches
that will be merged at the start of the next development cycle, after
the release.
* I use:
b4 am -3 -c -o <patches/dir> <lore.kernel.org link>
(you'd need to solve any conflicts with the base branch yourself)
> Also, patchew tells that that series has conflicts with master:
> https://patchew.org/QEMU/20260304212303.667141-1-vsementsov@yandex-team.ru/
>
> Should I manually download mbox, apply/resolve conflicts with master,
> then rebase my stuff and resend?
>
> Kind regards,
> Alex
>
>>
>> These codes weren't touched that frequent, it's interesting to see such
>> coinsidence happens. :)
>>
>> > ---
>> > include/migration/vmstate.h | 4 ++
>> > migration/vmstate.c | 84 +++++++++++++++++++++++--------------
>> > 2 files changed, 56 insertions(+), 32 deletions(-)
>> >
>> > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
>> > index 62c2abd0c49..5d7dfe70643 100644
>> > --- a/include/migration/vmstate.h
>> > +++ b/include/migration/vmstate.h
>> > @@ -1240,8 +1240,12 @@ extern const VMStateInfo vmstate_info_qlist;
>> > .flags = VMS_END, \
>> > }
>> >
>> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
>> > + const VMStateField *field, Error **errp);
>> > int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>> > void *opaque, int version_id, Error **errp);
>> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
>> > + const VMStateField *field, JSONWriter *vmdesc, Error **errp);
>> > int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
>> > void *opaque, JSONWriter *vmdesc, Error **errp);
>> > int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
>> > diff --git a/migration/vmstate.c b/migration/vmstate.c
>> > index 4d28364f7ba..8d192bcaa27 100644
>> > --- a/migration/vmstate.c
>> > +++ b/migration/vmstate.c
>> > @@ -131,6 +131,32 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
>> > }
>> > }
>> >
>> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
>> > + const VMStateField *field, Error **errp)
>> > +{
>> > + int ret = 0;
>> > +
>> > + if (field->flags & VMS_STRUCT) {
>> > + ret = vmstate_load_state(f, field->vmsd, pv,
>> > + field->vmsd->version_id,
>> > + errp);
>> > + } else if (field->flags & VMS_VSTRUCT) {
>> > + ret = vmstate_load_state(f, field->vmsd, pv,
>> > + field->struct_version_id,
>> > + errp);
>> > + } else {
>> > + ret = field->info->get(f, pv, size, field);
>> > + if (ret < 0) {
>> > + error_setg(errp,
>> > + "Failed to load element of type %s for %s: "
>> > + "%d", field->info->name,
>> > + field->name, ret);
>> > + }
>> > + }
>> > +
>> > + return ret;
>> > +}
>> > +
>> > int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>> > void *opaque, int version_id, Error **errp)
>> > {
>> > @@ -203,24 +229,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>> > inner_field = field;
>> > }
>> >
>> > - if (inner_field->flags & VMS_STRUCT) {
>> > - ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
>> > - inner_field->vmsd->version_id,
>> > - errp);
>> > - } else if (inner_field->flags & VMS_VSTRUCT) {
>> > - ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
>> > - inner_field->struct_version_id,
>> > - errp);
>> > - } else {
>> > - ret = inner_field->info->get(f, curr_elem, size,
>> > - inner_field);
>> > - if (ret < 0) {
>> > - error_setg(errp,
>> > - "Failed to load element of type %s for %s: "
>> > - "%d", inner_field->info->name,
>> > - inner_field->name, ret);
>> > - }
>> > - }
>> > + ret = vmstate_load_field(f, curr_elem, size, inner_field, errp);
>> >
>> > /* If we used a fake temp field.. free it now */
>> > if (inner_field != field) {
>> > @@ -427,6 +436,29 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
>> > return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
>> > }
>> >
>> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
>> > + const VMStateField *field, JSONWriter *vmdesc, Error **errp)
>> > +{
>> > + int ret = 0;
>> > +
>> > + if (field->flags & VMS_STRUCT) {
>> > + ret = vmstate_save_state(f, field->vmsd, pv, vmdesc, errp);
>> > + } else if (field->flags & VMS_VSTRUCT) {
>> > + ret = vmstate_save_state_v(f, field->vmsd, pv, vmdesc,
>> > + field->struct_version_id, errp);
>> > + } else {
>> > + ret = field->info->put(f, pv, size, field, vmdesc);
>> > + if (ret < 0) {
>> > + error_setg(errp,
>> > + "Failed to save element of type %s for %s: "
>> > + "%d", field->info->name,
>> > + field->name, ret);
>> > + }
>> > + }
>> > +
>> > + return ret;
>> > +}
>> > +
>> > int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
>> > void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
>> > {
>> > @@ -528,19 +560,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
>> > vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field,
>> > i, max_elems);
>> >
>> > - if (inner_field->flags & VMS_STRUCT) {
>> > - ret = vmstate_save_state(f, inner_field->vmsd,
>> > - curr_elem, vmdesc_loop, errp);
>> > - } else if (inner_field->flags & VMS_VSTRUCT) {
>> > - ret = vmstate_save_state_v(f, inner_field->vmsd,
>> > - curr_elem, vmdesc_loop,
>> > - inner_field->struct_version_id,
>> > - errp);
>> > - } else {
>> > - ret = inner_field->info->put(f, curr_elem, size,
>> > - inner_field, vmdesc_loop);
>> > - }
>> > -
>> > + ret = vmstate_save_field(f, curr_elem, size, inner_field, vmdesc_loop, errp);
>> > written_bytes = qemu_file_transferred(f) - old_offset;
>> > vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field,
>> > written_bytes);
>> > @@ -551,7 +571,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
>> > }
>> >
>> > if (ret) {
>> > - error_setg(errp, "Save of field %s/%s failed",
>> > + error_prepend(errp, "Save of field %s/%s failed: ",
>> > vmsd->name, field->name);
>> > if (vmsd->post_save) {
>> > vmsd->post_save(opaque);
>> > --
>> > 2.47.3
>> >
>>
>> --
>> Peter Xu
>>
Am Mo., 16. März 2026 um 15:57 Uhr schrieb Fabiano Rosas <farosas@suse.de>:
>
> Alexander Mikhalitsyn via qemu development <qemu-devel@nongnu.org>
> writes:
>
> > Am Fr., 13. März 2026 um 17:27 Uhr schrieb Peter Xu <peterx@redhat.com>:
> >>
> >> On Fri, Mar 13, 2026 at 03:12:14PM +0100, Alexander Mikhalitsyn wrote:
> >> > From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
> >> >
> >> > Let's introduce vmstate_{load,save}_field() helpers, they will
> >> > be used in next patches to support fully-dynamic arrays with NULLs.
> >> >
> >> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
> >>
> >
> > Hi Peter,
> >
> >> Feel free to rebase to Vladimir's series here, Fabiano already queued it:
> >>
> >> https://lore.kernel.org/all/20260304212303.667141-11-vsementsov@yandex-team.ru/#t
> >
> > I've tried, but I can't see it anywhere
> > https://gitlab.com/farosas/qemu/-/commits/migration-next
> > doesn't contain it. As of now, last commit is
> > 472f455cfbb0c5f84a7d48228d5226eaf6c7a61b.
> >
Hi Fabiano,
>
> I think we usually just take the patches from the list and apply
> directly instead of taking any branch*. I don't keep migration-next
> stable.
ah, makes sense.
>
> I pushed migration-staging which you can use. It'll collect the patches
> that will be merged at the start of the next development cycle, after
> the release.
Thank you!
>
> * I use:
> b4 am -3 -c -o <patches/dir> <lore.kernel.org link>
> (you'd need to solve any conflicts with the base branch yourself)
thanks for this, Fabiano! I'll try this out.
Kind regards,
Alex
>
> > Also, patchew tells that that series has conflicts with master:
> > https://patchew.org/QEMU/20260304212303.667141-1-vsementsov@yandex-team.ru/
> >
> > Should I manually download mbox, apply/resolve conflicts with master,
> > then rebase my stuff and resend?
> >
> > Kind regards,
> > Alex
> >
> >>
> >> These codes weren't touched that frequent, it's interesting to see such
> >> coinsidence happens. :)
> >>
> >> > ---
> >> > include/migration/vmstate.h | 4 ++
> >> > migration/vmstate.c | 84 +++++++++++++++++++++++--------------
> >> > 2 files changed, 56 insertions(+), 32 deletions(-)
> >> >
> >> > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> >> > index 62c2abd0c49..5d7dfe70643 100644
> >> > --- a/include/migration/vmstate.h
> >> > +++ b/include/migration/vmstate.h
> >> > @@ -1240,8 +1240,12 @@ extern const VMStateInfo vmstate_info_qlist;
> >> > .flags = VMS_END, \
> >> > }
> >> >
> >> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> >> > + const VMStateField *field, Error **errp);
> >> > int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >> > void *opaque, int version_id, Error **errp);
> >> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> >> > + const VMStateField *field, JSONWriter *vmdesc, Error **errp);
> >> > int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> >> > void *opaque, JSONWriter *vmdesc, Error **errp);
> >> > int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >> > diff --git a/migration/vmstate.c b/migration/vmstate.c
> >> > index 4d28364f7ba..8d192bcaa27 100644
> >> > --- a/migration/vmstate.c
> >> > +++ b/migration/vmstate.c
> >> > @@ -131,6 +131,32 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
> >> > }
> >> > }
> >> >
> >> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> >> > + const VMStateField *field, Error **errp)
> >> > +{
> >> > + int ret = 0;
> >> > +
> >> > + if (field->flags & VMS_STRUCT) {
> >> > + ret = vmstate_load_state(f, field->vmsd, pv,
> >> > + field->vmsd->version_id,
> >> > + errp);
> >> > + } else if (field->flags & VMS_VSTRUCT) {
> >> > + ret = vmstate_load_state(f, field->vmsd, pv,
> >> > + field->struct_version_id,
> >> > + errp);
> >> > + } else {
> >> > + ret = field->info->get(f, pv, size, field);
> >> > + if (ret < 0) {
> >> > + error_setg(errp,
> >> > + "Failed to load element of type %s for %s: "
> >> > + "%d", field->info->name,
> >> > + field->name, ret);
> >> > + }
> >> > + }
> >> > +
> >> > + return ret;
> >> > +}
> >> > +
> >> > int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >> > void *opaque, int version_id, Error **errp)
> >> > {
> >> > @@ -203,24 +229,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >> > inner_field = field;
> >> > }
> >> >
> >> > - if (inner_field->flags & VMS_STRUCT) {
> >> > - ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> >> > - inner_field->vmsd->version_id,
> >> > - errp);
> >> > - } else if (inner_field->flags & VMS_VSTRUCT) {
> >> > - ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> >> > - inner_field->struct_version_id,
> >> > - errp);
> >> > - } else {
> >> > - ret = inner_field->info->get(f, curr_elem, size,
> >> > - inner_field);
> >> > - if (ret < 0) {
> >> > - error_setg(errp,
> >> > - "Failed to load element of type %s for %s: "
> >> > - "%d", inner_field->info->name,
> >> > - inner_field->name, ret);
> >> > - }
> >> > - }
> >> > + ret = vmstate_load_field(f, curr_elem, size, inner_field, errp);
> >> >
> >> > /* If we used a fake temp field.. free it now */
> >> > if (inner_field != field) {
> >> > @@ -427,6 +436,29 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> >> > return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
> >> > }
> >> >
> >> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> >> > + const VMStateField *field, JSONWriter *vmdesc, Error **errp)
> >> > +{
> >> > + int ret = 0;
> >> > +
> >> > + if (field->flags & VMS_STRUCT) {
> >> > + ret = vmstate_save_state(f, field->vmsd, pv, vmdesc, errp);
> >> > + } else if (field->flags & VMS_VSTRUCT) {
> >> > + ret = vmstate_save_state_v(f, field->vmsd, pv, vmdesc,
> >> > + field->struct_version_id, errp);
> >> > + } else {
> >> > + ret = field->info->put(f, pv, size, field, vmdesc);
> >> > + if (ret < 0) {
> >> > + error_setg(errp,
> >> > + "Failed to save element of type %s for %s: "
> >> > + "%d", field->info->name,
> >> > + field->name, ret);
> >> > + }
> >> > + }
> >> > +
> >> > + return ret;
> >> > +}
> >> > +
> >> > int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >> > void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
> >> > {
> >> > @@ -528,19 +560,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >> > vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field,
> >> > i, max_elems);
> >> >
> >> > - if (inner_field->flags & VMS_STRUCT) {
> >> > - ret = vmstate_save_state(f, inner_field->vmsd,
> >> > - curr_elem, vmdesc_loop, errp);
> >> > - } else if (inner_field->flags & VMS_VSTRUCT) {
> >> > - ret = vmstate_save_state_v(f, inner_field->vmsd,
> >> > - curr_elem, vmdesc_loop,
> >> > - inner_field->struct_version_id,
> >> > - errp);
> >> > - } else {
> >> > - ret = inner_field->info->put(f, curr_elem, size,
> >> > - inner_field, vmdesc_loop);
> >> > - }
> >> > -
> >> > + ret = vmstate_save_field(f, curr_elem, size, inner_field, vmdesc_loop, errp);
> >> > written_bytes = qemu_file_transferred(f) - old_offset;
> >> > vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field,
> >> > written_bytes);
> >> > @@ -551,7 +571,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >> > }
> >> >
> >> > if (ret) {
> >> > - error_setg(errp, "Save of field %s/%s failed",
> >> > + error_prepend(errp, "Save of field %s/%s failed: ",
> >> > vmsd->name, field->name);
> >> > if (vmsd->post_save) {
> >> > vmsd->post_save(opaque);
> >> > --
> >> > 2.47.3
> >> >
> >>
> >> --
> >> Peter Xu
> >>
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