RFC ARM: add QMP command to query GIC version

For ARM platform, we still do not have any interface to query whether current QEMU/host support specific GIC version. This patchset is trying to add one QMP interface for that. By querying the GIC capability using the new interface, one should know exactly what GIC version(s) the platform will support. The capability bits will be decided by both QEMU and host kernel.

The current patchset only provides interface for review. Its handler is a fake one which returns empty always.

The command interface I am planning to add is something like this:

-> { "execute": "query-gic-capability" }
<- { "return": [ "gicv2", "gicv2-kvm", "gicv3-kvm" ] }

Currently, all the possible supported GIC versions are:

- gicv2:      GIC version 2 without kernel IRQ chip
- gicv2-kvm:  GIC version 2 with kernel IRQ chip
- gicv3:      GIC version 3 without kernel IRQ chip (not supported)
- gicv3-kvm:  GIC version 3 with kernel IRQ chip

Since "gicv3" is still not supported (to use GICv3, kernel irqchip support is required for now, which corresponds to "gicv3-kvm"), currently the maximum superset of the result should be:

["gicv2", "gicv2-kvm", "gicv3-kvm"]

Please help review whether the interface suits our need, also please point out any error I have made.

One question: how should I make this command "ARM only"? I see that in qmp-commands.hx, I can use something like "#if defined TARGET_ARM" to block out ARM specified commands, however how should I do the similiar thing in qapi-schema.json?

Thanks!
Peter

Peter Xu (2):
arm: gic: add GICType
arm: gic: add "query-gic-capability" interface

 qapi-schema.json | 28 ++++++++++++++++++++++++++++
 qmp-commands.hx  | 25 +++++++++++++++++++++++++
 qmp.c            |  5 +++++
 scripts/qapi.py  |  1 +
 4 files changed, 59 insertions(+)

2.4.3