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

[Marc Zyngier]

On Wed, Dec 18 2013 at 03:52:29 PM, Anup Patel <anup at brainfault.org> wrote:
> On Wed, Dec 18, 2013 at 9:11 PM, Marc Zyngier <marc.zyngier at arm.com> wrote:
>> 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)
>
> Does this mean we should have first isolate v0.2 ID range
> from v0.1 ID range?

Yes.

> And then...
>
> Rebase this patchset based on new v0.2 ID range?

Indeed.

Thanks,

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