linux-kernel - Re: [PATCH kernel] KVM: PPC: Make KVM_CAP_IRQFD

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Date:   Fri, 16 Sep 2022 10:00:45 +0100
From:   Marc Zyngier <maz@...terjones.org>
To:     Alexey Kardashevskiy <aik@...abs.ru>
Cc:     kvm-ppc@...r.kernel.org, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org, Fabiano Rosas <farosas@...ux.ibm.com>,
        x86@...nel.org, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Alex Williamson <alex.williamson@...hat.com>,
        kvm-riscv@...ts.infradead.org, Paolo Bonzini <pbonzini@...hat.com>,
        linux-riscv@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
        kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH kernel] KVM: PPC: Make KVM_CAP_IRQFD_RESAMPLE platform
 dependent

On 2022-09-13 13:50, Alexey Kardashevskiy wrote:
> Ping? It's been a while and probably got lost :-/
> 
> On 18/05/2022 16:27, Alexey Kardashevskiy wrote:
>> 
>> 
>> On 5/4/22 17:48, Alexey Kardashevskiy wrote:
>>> When introduced, IRQFD resampling worked on POWER8 with XICS. However
>>> KVM on POWER9 has never implemented it - the compatibility mode code
>>> ("XICS-on-XIVE") misses the kvm_notify_acked_irq() call and the 
>>> native
>>> XIVE mode does not handle INTx in KVM at all.
>>> 
>>> This moved the capability support advertising to platforms and stops
>>> advertising it on XIVE, i.e. POWER9 and later.
>>> 
>>> Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
>>> ---
>>> 
>>> 
>>> Or I could move this one together with KVM_CAP_IRQFD. Thoughts?
>> 
>> 
>> Ping?
>> 
>>> 
>>> ---
>>>   arch/arm64/kvm/arm.c       | 3 +++
>>>   arch/mips/kvm/mips.c       | 3 +++
>>>   arch/powerpc/kvm/powerpc.c | 6 ++++++
>>>   arch/riscv/kvm/vm.c        | 3 +++
>>>   arch/s390/kvm/kvm-s390.c   | 3 +++
>>>   arch/x86/kvm/x86.c         | 3 +++
>>>   virt/kvm/kvm_main.c        | 1 -
>>>   7 files changed, 21 insertions(+), 1 deletion(-)
>>> 
>>> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
>>> index 523bc934fe2f..092f0614bae3 100644
>>> --- a/arch/arm64/kvm/arm.c
>>> +++ b/arch/arm64/kvm/arm.c
>>> @@ -210,6 +210,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, 
>>> long ext)
>>>       case KVM_CAP_SET_GUEST_DEBUG:
>>>       case KVM_CAP_VCPU_ATTRIBUTES:
>>>       case KVM_CAP_PTP_KVM:
>>> +#ifdef CONFIG_HAVE_KVM_IRQFD
>>> +    case KVM_CAP_IRQFD_RESAMPLE:
>>> +#endif

I don't mind moving this around, but I object to the #ifdefery.

This option is always selected on arm64, so it can safely be added
to the list without any condition.

Thanks,

         M.
-- 
Who you jivin' with that Cosmik Debris?