Subject: [PATCH v6 02/21] KVM: ARM64: Define PMU data structure for each vcpu

From: [email-masked] (Shannon Zhao)
Date: Tue, 08 Dec 2015 22:14:29 +0800

On 2015/12/8 22:10, Marc Zyngier wrote:
> On 08/12/15 13:53, Will Deacon wrote:
>> On Tue, Dec 08, 2015 at 01:37:14PM +0000, Marc Zyngier wrote:
>>> On 08/12/15 12:47, Shannon Zhao wrote:
>>>> From: Shannon Zhao <[email-masked]>
>>>>
>>>> Here we plan to support virtual PMU for guest by full software
>>>> emulation, so define some basic structs and functions preparing for
>>>> futher steps. Define struct kvm_pmc for performance monitor counter and
>>>> struct kvm_pmu for performance monitor unit for each vcpu. According to
>>>> ARMv8 spec, the PMU contains at most 32(ARMV8_MAX_COUNTERS) counters.
>>>>
>>>> Since this only supports ARM64 (or PMUv3), add a separate config symbol
>>>> for it.
>>>>
>>>> Signed-off-by: Shannon Zhao <[email-masked]>
>>>> ---
>>>>   arch/arm64/include/asm/kvm_host.h |  2 ++
>>>>   arch/arm64/kvm/Kconfig            |  8 ++++++++
>>>>   include/kvm/arm_pmu.h             | 40 +++++++++++++++++++++++++++++++++++++++
>>>>   3 files changed, 50 insertions(+)
>>>>   create mode 100644 include/kvm/arm_pmu.h
>>
>> [...]
>>
>>>> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
>>>> index a5272c0..66da9a2 100644
>>>> --- a/arch/arm64/kvm/Kconfig
>>>> +++ b/arch/arm64/kvm/Kconfig
>>>> @@ -36,6 +36,7 @@ config KVM
>>>>   	select HAVE_KVM_EVENTFD
>>>>   	select HAVE_KVM_IRQFD
>>>>   	select KVM_ARM_VGIC_V3
>>>> +	select KVM_ARM_PMU
>>>
>>> What if HW_PERF_EVENTS is not selected? Also, selecting HW_PERF_EVENTS
>>> is not enough, and you probably need PERF_EVENTS as well, So this should
>>> probably read:
>>>
>>> 	select KVM_ARM_PMU if (HW_PERF_EVENTS && PERF_EVENTS)
>>
>> HW_PERF_EVENTS depends on ARM_PMU which in turn depends on PERF_EVENTS.
>
Yeah, this is the reason why I choose HW_PERF_EVENTS.

> in which case, let's make it:
>
> 	select KVM_ARM_PMU if HW_PERF_EVENTS
>
Sure, will do.

> which should give us the minimal chain. I hate the kernel config
> language! ;-)
>
> 	M.
>

-- 
Shannon