[PATCH v3 1/8] arm64: KVM: Use static keys for selecting the GIC backend

[Marc Zyngier]

On 09/09/16 17:18, Vladimir Murzin wrote:
> On 09/09/16 16:25, Marc Zyngier wrote:
>> On 09/09/16 16:14, Vladimir Murzin wrote:
>>> On 09/09/16 15:17, Marc Zyngier wrote:
>>>> On 09/09/16 14:45, Vladimir Murzin wrote:
>>>>> On 09/09/16 10:33, Vladimir Murzin wrote:
>>>>>> Hi Marc,
>>>>>>
>>>>>> On 09/09/16 10:19, Marc Zyngier wrote:
>>>>>>>> Hi Vladimir,
>>>>>>>>
>>>>>> ...
>>>>>>>>>>  
>>>>>>>>>> +extern struct static_key_false kvm_gicv3_cpuif;
>>>>>>>>
>>>>>>>> I think we should follow the model set by kvm_vgic_global_state, which
>>>>>>>> is declared in arm_vgic.h. Even better, we should *embed* the static key
>>>>>>>> in this structure. This will reduce the clutter and we wouldn't have to
>>>>>>>> deal with all the section stuff (the hyp_data thing is a good cleanup,
>>>>>>>> but I'd like to see it as a separate patch if possible).
>>>>>> Yes, it is what I was thinking about too, but was not sure about which
>>>>>> way to go, so hyp_data seemed me something we might reuse latter.
>>>>>> However, I agree that we can defer hyp_data thing...
>>>>>>
>>>>>
>>>>> I've just tried it out and it seems that static keys are not happy to
>>>>> accept a key after kern_hyp_va is applied at &kvm_vgic_global_state:
>>>>
>>>> Ah, there is a trick. You do not need kern_hyp_va at all, because this
>>>> is not evaluated as an expression at runtime (so the pointer doesn't matter).
>>>>
>>>
>>> Ah, right, thank for a tip! ;)
>>>
>>>>>> In file included from ./include/linux/jump_label.h:105:0,
>>>>>>                  from arch/arm64/kvm/hyp/switch.c:19:
>>>>>> ./arch/arm64/include/asm/jump_label.h: In function ‘__guest_run’:
>>>>>> ./arch/arm64/include/asm/jump_label.h:31:2: warning: asm operand 0 probably doesn’t match constraints
>>>>>>   asm goto("1: nop\n\t"
>>>>>>   ^
>>>>>> ./arch/arm64/include/asm/jump_label.h:31:2: warning: asm operand 0 probably doesn’t match constraints
>>>>>>   asm goto("1: nop\n\t"
>>>>>>   ^
>>>>>> ./arch/arm64/include/asm/jump_label.h:31:2: error: impossible constraint in ‘asm’
>>>>>>   asm goto("1: nop\n\t"
>>>>>>   ^
>>>>>> ./arch/arm64/include/asm/jump_label.h:31:2: error: impossible constraint in ‘asm’
>>>>>>   asm goto("1: nop\n\t"
>>>>>>   ^
>>>>>> make[1]: *** [arch/arm64/kvm/hyp/switch.o] Error 1
>>>>>> make: *** [arch/arm64/kvm/hyp/switch.o] Error 2
>>>>>
>>>>> it looks like we cannot avoid hyp_data thing... if you don't mind I can
>>>>> do hyp_data clean-up in separate patch. Alternatively, we can do
>>>>> conversion to static keys for both architectures later as an
>>>>> optimisation step.
>>>>
>>>> Can you try the above first? I've just tried the same approach with my
>>>> vgic-trap series, and it compiles fine (untested though):
>>>
>>> I was about to try it out, but didn't manage to find a branch with
>>> vgic-trap series, so I did a quick fixup for my series and now it is
>>> running non-VHE boot tests and I don't expect issues with VHE one. I
>>> think diff bellow should work runtime too, but if you do want me to give
>>> it a try it'd be handy to have a branch I can pull from ;)
>>
>> I think Christoffer has pulled it into kvmarm/queue.
> 
> Nothing has exploded so far for both architectures.

Great. Hopefully you can respin the series next week.

Thanks,

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