acpi: fix acpi_index migration

vmstate_acpi_pcihp_use_acpi_index() was expecting AcpiPciHpState
as state but it actually received PIIX4PMState, because
VMSTATE_PCI_HOTPLUG is a macro and not another struct.
So it ended up accessing random pointer, which resulted
in 'false' return value and acpi_index field wasn't ever

However in 7.0 that pointer de-references to value > 0, and
destination QEMU starts to expect the field which isn't
sent in migratioon stream from older QEMU (6.2 and older).
As result migration fails with:
  qemu-system-x86_64: Missing section footer for 0000:00:01.3/piix4_pm
  qemu-system-x86_64: load of migration failed: Invalid argument

In addition with QEMU-6.2, destination due to not expected
state, also never expects the acpi_index field in migration

Q35 is not affected as it always sends/expects the field as
long as acpi based PCI hotplug is enabled.

Fix issue by introducing compat knob to never send/expect
acpi_index in migration stream for 6.2 and older PC machine
types and always send it for 7.0 and newer PC machine types.

Diagnosed-by: Dr. David Alan Gilbert <>
Fixes: b32bd76 ("pci: introduce acpi-index property for PCI device")
Signed-off-by: Igor Mammedov <>
Reviewed-by: Dr. David Alan Gilbert <>
Signed-off-by: Peter Maydell <>
5 files changed