From: Peter Xu <peterx@redhat.com>
To: Alexander Mikhalitsyn <alexander@mihalicyn.com>
Cc: qemu-devel@nongnu.org, "Jesper Devantier" <foss@defmacro.it>,
"Kevin Wolf" <kwolf@redhat.com>,
"Fabiano Rosas" <farosas@suse.de>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Hanna Reitz" <hreitz@redhat.com>,
qemu-block@nongnu.org, "Stéphane Graber" <stgraber@stgraber.org>,
"Keith Busch" <kbusch@kernel.org>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@linaro.org>,
"Fam Zheng" <fam@euphon.net>, "Klaus Jensen" <its@irrelevant.dk>,
"Zhao Liu" <zhao1.liu@intel.com>,
"Alexander Mikhalitsyn" <aleksandr.mikhalitsyn@futurfusion.io>
Subject: Re: [PATCH v4 1/8] migration/vmstate: introduce vmstate_{load,save}_field helpers
Date: Fri, 13 Mar 2026 12:27:52 -0400 [thread overview]
Message-ID: <abQ7CLuJsWRLwoe5@x1.local> (raw)
In-Reply-To: <20260313141221.359503-2-alexander@mihalicyn.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>
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
next prev parent reply other threads:[~2026-03-13 16:28 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-13 14:12 [PATCH v4 0/8] hw/nvme: add basic live migration support Alexander Mikhalitsyn
2026-03-13 14:12 ` [PATCH v4 1/8] migration/vmstate: introduce vmstate_{load, save}_field helpers Alexander Mikhalitsyn via qemu development
2026-03-13 16:27 ` Peter Xu [this message]
2026-03-16 11:09 ` Alexander Mikhalitsyn via qemu development
2026-03-16 14:57 ` Fabiano Rosas
2026-03-16 15:11 ` Alexander Mikhalitsyn
2026-03-13 14:12 ` [PATCH v4 2/8] migration: add VMSTATE_VARRAY_OF_POINTER_TO_STRUCT_UINT{8, 32}_ALLOC Alexander Mikhalitsyn
2026-03-13 14:12 ` [PATCH v4 3/8] tests/unit/test-vmstate: add tests for VMS_ARRAY_OF_POINTER_ALLOW_NULL Alexander Mikhalitsyn
2026-03-13 14:12 ` [PATCH v4 4/8] tests/functional/migration: add VM launch/configure hooks Alexander Mikhalitsyn
2026-03-13 14:12 ` [PATCH v4 5/8] hw/nvme: add migration blockers for non-supported cases Alexander Mikhalitsyn
2026-03-13 14:12 ` [PATCH v4 6/8] hw/nvme: split nvme_init_sq/nvme_init_cq into helpers Alexander Mikhalitsyn
2026-03-13 14:12 ` [PATCH v4 7/8] hw/nvme: add basic live migration support Alexander Mikhalitsyn
2026-03-13 14:12 ` [PATCH v4 8/8] tests/functional/x86_64: add migration test for NVMe device Alexander Mikhalitsyn
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