QEMU reports whether 'query-hotpluggable-cpus' is supported for a given
machine type. Extract and cache the information using the capability
cache.
When copying the capabilities for a new start of qemu, mask out the
presence of QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS if the machine type
doesn't support hotpluggable cpus.
Check whether the disable-legacy property is present on the following
devices:
virtio-balloon-pci
virtio-blk-pci
virtio-scsi-pci
virtio-serial-pci
virtio-9p-pci
virtio-net-pci
virtio-rng-pci
virtio-gpu-pci
virtio-input-host-pci
virtio-keyboard-pci
virtio-mouse-pci
virtio-tablet-pci
Assuming that if QEMU knows other virtio devices where this property
is applicable, it will have at least one of these devices.
Added in QEMU by:
commit e266d421490e0ae83044bbebb209b2d3650c0ba6
virtio-pci: add flags to enable/disable legacy/modern
