[Qemu-devel] PowerPC KVM support

[Hollis Blanchard <hollisb@us.ibm.com>]

These patches implement KVM support for the PowerPC Bamboo board, a system
built around the 440EP SoC. In the KVM model, the KVM kernel module is
responsible for all instruction execution, so it doesn't matter that TCG
doesn't emulate the 440 core.

We've only tested KVM and Bamboo with the -kernel option. I have no idea what
it would take to run a firmware like u-boot inside the VM, but it's basically
the same problem as running u-boot inside a 405 VM (which I know
Jean-Christophe is working on).

There are a couple issues I'd appreciate feedback on:

- The "bamboo" machine shows up as an option ("-M \?"), but if a user selects
  it without KVM support, they will just get an error. I don't like that, but
  register_machines() is called before --enable-kvm is recognized.

- We call cpu_ppc_init("405") to create a CPUState, because some CPUState
  fields are required outside of TCG. We could instead create a "KVM" CPU
  name, or a cpu_ppc_init_kvm() function. I'd prefer to stay on a common code
  path though, so that if new CPUState fields are introduced in the future,
  there's no KVM-specific path that breaks.

- I'd like to use ppc4xx_sdram_adjust() with the existing 405 targets as well,
  but nobody can tell me how to get a functioning 405 qemu so I can't test it.
  I may submit a separate patch series for this anyways.

-Hollis