On Mon, Oct 27, 2025 at 08:06:04PM +0300, Vladimir Sementsov-Ogievskiy wrote:
Understand.. So we don't know, does any caller use this ENOMEM, or not. And
want to save
a chance for bulk conversion.
And blind bulk conversion of all -errno to simple true/false may break
something, we
don't know.
Reasonable. Thanks for the explanation.
Taking vmstate_load_state() as example: most of its callers should
ultimately route back to the top of vmstate_load_state() that migration
code invokes.
AFAIU, migration itself doesn't care much so far on the retval, but only
succeeded or not, plus the errp as a bonus. There's one thing exception
that I remember but it was removed in commit fd037a656aca.. So now I
cannot find anything relies on that.
Here's a list of all current vmstate_load_state() callers:
*** hw/display/virtio-gpu.c:
virtio_gpu_load[1358] ret = vmstate_load_state(f,
&vmstate_virtio_gpu_scanouts, g, 1, &err);
*** hw/pci/pci.c:
pci_device_load[943] ret = vmstate_load_state(f, &vmstate_pci_device, s,
s->version_id,
*** hw/s390x/virtio-ccw.c:
virtio_ccw_load_config[1146] ret = vmstate_load_state(f, &vmstate_virtio_ccw_dev,
dev, 1, &local_err);
*** hw/scsi/spapr_vscsi.c:
vscsi_load_request[657] rc = vmstate_load_state(f, &vmstate_spapr_vscsi_req,
req, 1, &local_err);
Until here, it's invoked in a get() callback of VMStateInfo. Ultimately,
it goes back to migration's vmstate_load_state() invokation.
*** hw/vfio/pci.c:
vfio_pci_load_config[2840] ret = vmstate_load_state(f,
&vmstate_vfio_pci_config, vdev, 1,
This is special as it's part of load_state(). However it's the same, it
routes back to vmstate_load() instead (where vmstate_load_state()
ultimately also routes there). So looks safe too.
*** hw/virtio/virtio-mmio.c:
virtio_mmio_load_extra_state[630] ret = vmstate_load_state(f, &vmstate_virtio_mmio,
proxy, 1, &local_err);
*** hw/virtio/virtio-pci.c:
virtio_pci_load_extra_state[205] ret = vmstate_load_state(f, &vmstate_virtio_pci,
proxy, 1, &local_err);
*** hw/virtio/virtio.c:
virtio_load[3394] ret = vmstate_load_state(f, vdc->vmsd, vdev,
version_id, &local_err);
virtio_load[3402] ret = vmstate_load_state(f, &vmstate_virtio, vdev,
1, &local_err);
More get() users. Same.
*** migration/cpr.c:
cpr_state_load[266] ret = vmstate_load_state(f, &vmstate_cpr_state,
&cpr_state, 1, errp);
This is special, ignoring retval but using error_abort. New one, safe.
*** migration/savevm.c:
vmstate_load[978] return vmstate_load_state(f, se->vmsd, se->opaque,
se->load_version_id,
qemu_loadvm_state_header[2885] ret = vmstate_load_state(f, &vmstate_configuration,
&savevm_state, 0,
This is the migration core invokations. Safe.
*** migration/vmstate-types.c:
get_tmp[562] ret = vmstate_load_state(f, vmsd, tmp, version_id,
&local_err);
get_qtailq[670] ret = vmstate_load_state(f, vmsd, elm, version_id,
&local_err);
get_gtree[833] ret = vmstate_load_state(f, key_vmsd, key,
version_id, &local_err);
get_gtree[840] ret = vmstate_load_state(f, val_vmsd, val,
version_id, &local_err);
get_qlist[921] ret = vmstate_load_state(f, vmsd, elm, version_id,
&local_err);
These are special get() for special VMSD fields. Safe.
*** migration/vmstate.c:
vmstate_load_state[208] ret = vmstate_load_state(f, inner_field->vmsd,
curr_elem,
vmstate_load_state[212] ret = vmstate_load_state(f, inner_field->vmsd,
curr_elem,
vmstate_subsection_load[652] ret = vmstate_load_state(f, sub_vmsd, opaque,
version_id, errp);
Same migration core invokations. Safe.
*** tests/unit/test-vmstate.c:
load_vmstate_one[123] ret = vmstate_load_state(f, desc, obj, version,
&local_err);
test_load_v1[377] ret = vmstate_load_state(loading, &vmstate_versioned,
&obj, 1, &local_err);
test_load_v2[408] ret = vmstate_load_state(loading, &vmstate_versioned,
&obj, 2, &local_err);
test_load_noskip[512] ret = vmstate_load_state(loading, &vmstate_skipping,
&obj, 2, &local_err);
test_load_skip[541] ret = vmstate_load_state(loading, &vmstate_skipping,
&obj, 2, &local_err);
test_load_q[815] ret = vmstate_load_state(fload, &vmstate_q, &tgt, 1,
&local_err);
test_gtree_load_domain[1174] ret = vmstate_load_state(fload, &vmstate_domain,
dest_domain, 1,
test_gtree_load_iommu[1294] ret = vmstate_load_state(fload, &vmstate_iommu,
dest_iommu, 1, &local_err);
test_load_qlist[1434] ret = vmstate_load_state(fload,
&vmstate_container, dest_container, 1,
Test code only. Safe.
*** ui/vdagent.c:
get_cbinfo[1013] ret = vmstate_load_state(f, &vmstate_cbinfo_array,
&cbinfo, 0,
Yet another get(). Safe.
So.. even if I'm not sure if a bulk conversion could happen or not (the
get() users above would be very tricky because get() doesn't allow errp so
far.. unless we introduce that too), but other than that, afaict,
vmstate_load_state() callers do not yet care about retvals.
