[PATCH] KVM: arm/arm64: Access CNTHCTL_EL2 bit fields correctly

Jintack Lim jintack at cs.columbia.edu
Wed Nov 30 05:41:43 PST 2016


On Wed, Nov 30, 2016 at 8:31 AM, Marc Zyngier <marc.zyngier at arm.com> wrote:
> On 29/11/16 21:05, Jintack Lim wrote:
>> On Tue, Nov 29, 2016 at 11:53 AM, Suzuki K Poulose
>> <suzuki.poulose at arm.com> wrote:
>>> On 29/11/16 09:36, Marc Zyngier wrote:
>>>>
>>>> On 29/11/16 03:28, Jintack Lim wrote:
>>>>>
>>>>> On Mon, Nov 28, 2016 at 1:39 PM, Marc Zyngier <marc.zyngier at arm.com>
>>>>> wrote:
>>>>>>
>>>>>> On 28/11/16 17:43, Marc Zyngier wrote:
>>>>>
>>>>> This looks much cleaner than my patch.
>>>>> While we are at it, is it worth to consider that we just need to set
>>>>> those bits once for VHE case, not for every world switch as an
>>>>> optimization?
>>>>
>>>>
>>>> Ah! That's a much better idea indeed! And we could stop messing with
>>>> cntvoff_el2 as well, as it doesn't need to be restored to zero on exit.
>>>> Could you try and respin something along those lines?
>>>>
>>>
>>> fyi, we have a static_key based cpus_have_const_cap() for Constant cap
>>> checking (like this case) available in linux-next. May be you could make use
>>> of that instead of alternatives.
>>
>> Thanks Suzuki. This looks very useful.
>>
>> Marc, can I write a patch based on linux-next? The commit which has
>> cpus_have_const_cap() is not in master and next branch in kvm/arm
>> repo.
>
> You can. It is just that I won't be able to apply it immediately (I'll
> wait for -rc1 to be out, and send it as a fix).

Ok. Thanks!. I'll send out v2.

>
> Thanks,
>
>         M.
> --
> Jazz is not dead. It just smells funny...
>




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