From 12c81e5ae9aa226f1200ecf25153d350e92cf387 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Tue, 25 Apr 2023 14:05:43 -0400 Subject: [PATCH] migration/vmstate-dump: Dump array size too as "num" For VMS_ARRAY typed vmsd fields, also dump the number of entries in the array in -vmstate-dump. Without such information, vmstate static checker can report false negatives of incompatible vmsd on VMS_ARRAY typed fields, when the src/dst do not have the same type of array defined. It's because in the checker we only check against size of fields within a VMSD field. One example: e1000e used to have a field defined as a boolean array with 5 entries, then removed it and replaced it with UNUSED (in 31e3f318c8b535): - VMSTATE_BOOL_ARRAY(core.eitr_intr_pending, E1000EState, - E1000E_MSIX_VEC_NUM), + VMSTATE_UNUSED(E1000E_MSIX_VEC_NUM), It's a legal replacement but vmstate static checker is not happy with it, because it checks only against the "size" field between the two fields (here one is BOOL_ARRAY, the other is UNUSED): For BOOL_ARRAY: { "field": "core.eitr_intr_pending", "version_id": 0, "field_exists": false, "size": 1 }, For UNUSED: { "field": "unused", "version_id": 0, "field_exists": false, "size": 5 }, It's not the script to blame because there's just not enough information dumped to show the total size of the entry for an array. Add it. Note that this will not break old vmstate checker because the field will just be ignored. Signed-off-by: Peter Xu Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- migration/savevm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/migration/savevm.c b/migration/savevm.c index 211eff3a8b..a9181b444b 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -536,6 +536,9 @@ static void dump_vmstate_vmsf(FILE *out_file, const VMStateField *field, field->version_id); fprintf(out_file, "%*s\"field_exists\": %s,\n", indent, "", field->field_exists ? "true" : "false"); + if (field->flags & VMS_ARRAY) { + fprintf(out_file, "%*s\"num\": %d,\n", indent, "", field->num); + } fprintf(out_file, "%*s\"size\": %zu", indent, "", field->size); if (field->vmsd != NULL) { fprintf(out_file, ",\n");