Re: [PATCH v2] ArmPkg/TimerDxe: remove workaround for KVM timer handling

[Julien Grall <julien.grall@arm.com>]

On 19/04/18 15:34, Ard Biesheuvel wrote:
> On 19 April 2018 at 16:23, Julien Grall <julien.grall@arm.com> wrote:
>> Hi Ard,
>>
>> Sorry for the late reply.
>>
>> On 19/04/18 09:16, Ard Biesheuvel wrote:
>>>
>>> On 17 April 2018 at 08:03, Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>> wrote:
>>>>
>>>> When we first ported EDK2 to KVM/arm, we implemented a workaround for
>>>> the quirky timer handling on the KVM side. This has been fixed in
>>>> Linux commit f120cd6533d2 ("KVM: arm/arm64: timer: Allow the timer to
>>>> control the active state") dated 23 June 2014, which was incorporated
>>>> into Linux release 4.3.
>>>>
>>>> So almost 4 years later, it should be safe to drop this workaround on
>>>> the EDK2 side.
>>>>
>>>> This reverts commit b1a633434ddc.
>>>>
>>>> Cc: cross-distro@lists.linaro.org
>>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>>> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
>>>> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
>>>> Acked-by: Laszlo Ersek <lersek@redhat.com>
>>>
>>>
>>> Pushed as 411a373ed6426fb1bff253905b6a59ada44e18ad
>>
>>
>> While this was added for KVM, I believe that code is also needed by Xen.
>> Indeed before injecting the interrupt the hypervisor will mask the
>> interrupt.
>>
>> So would it be possible to revert that patch?
>>
> 
> Given that this is now a Xen-only quirk, I'd rather work around it by
> creating a separate ArmGenericTimerCounterLib implementation for Xen.

That would work for me.

> 
> I will try to put something together beginning of next week.

I am happy to test it.

Cheers,

-- 
Julien Grall