[PATCH v3 0/2] PSCI system off and reset for KVM ARM/ARM64

[Marc Zyngier]

Hi Anup,

On Wed, Dec 18 2013 at 03:03:43 PM, Anup Patel <anup at brainfault.org> wrote:
> On Wed, Dec 18, 2013 at 8:08 PM, Marc Zyngier <marc.zyngier at arm.com> wrote:
>> Christoffer Dall <christoffer.dall at linaro.org> writes:
>>
>>> On Tue, Dec 17, 2013 at 05:05:34PM +0530, Anup Patel wrote:
>>>> The Power State and Coordination Interface (PSCI) specification defines
>>>> SYSTEM_OFF and SYSTEM_RESET functions for system poweroff and reboot.
>>>>
>>>> This patchset adds emulation of PSCI SYSTEM_OFF and SYSTEM_RESET functions
>>>> in KVM ARM/ARM64 by forwarding them to user space (QEMU or KVMTOOL) using
>>>> KVM_EXIT_SYSTEM_EVENT exit reason.
>>>>
>>>> To try this patch from guest kernel, we will need PSCI-based restart and
>>>> poweroff support in the guest kenel for both ARM and ARM64.
>>>>
>>>> Rob Herring has already submitted patches for PSCI-based restart and
>>>> poweroff in ARM kernel but these are not merged yet due unstable device
>>>> tree bindings of kernel PSCI support. We will be having similar patches
>>>> for PSCI-based restart and poweroff in ARM64 kernel.
>>>> (Refer http://www.spinics.net/lists/arm-kernel/msg262217.html)
>>>> (Refer http://www.spinics.net/lists/devicetree/msg05348.html)
>>>
>>> Reviewed-by: Christoffer Dall <christoffer.dall at linaro.org>
>>>
>>> I can merge this series if Marc acks it as well.
>>
>> The patches themselves are mostly fine. One issue though: They implement
>> part of the v0.2 spec, but keep on using the range of function IDs that
>> we made up for v0.1.
>>
>> I just had a chat with the person responsible for the spec, and realized
>> that the Function IDs mentionned in the v0.2 spec are not optional, and
>> not using them would be in direct violation of the spec (the new numbers
>> now come directly from the SMC calling convention).
>
> Should we emulate PSCI_VERSION call to help Guest determine
> the spec version emulated by KVM (i.e. v0.1 or v0.2) ??

I think that'd be a nice to have, but the guest is likely to get its
information from the DT anyway. Plus I don't think the original PSCI
spec specified PSCI_VERSION, which only make it useful for whatever
comes after v0.2.

So I think we need to:
- Use the new range for PSCI v0.2 (while still supporting v0.1 and the
old range)
- Get the kernel and DT bindings into shape
- Merge all of that at the same time

Cheers,

        M.
-- 
Jazz is not dead. It just smells funny.