Re: [PATCH 3/4] KVM: i8254: remove unnecessary irqchip_in_kernel check

From: Steve Rutherford
Date: Thu Jul 30 2015 - 00:36:52 EST


On Wed, Jul 29, 2015 at 03:28:57PM +0200, Paolo Bonzini wrote:
> The PIT is only created if irqchip_in_kernel returns true, so the
> check is superfluous.
I poked around. Looks to me like the existence of an IOAPIC is not
checked on the creation of the in-kernel PIT. Userspace might limit itself to
that scenario (PIT implies IOAPIC in-kernel), but that isn't enforced at PIT
creation.

It's worth adding that check in.

>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> arch/x86/kvm/i8254.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
> index f90952f64e79..f588eb7bdf45 100644
> --- a/arch/x86/kvm/i8254.c
> +++ b/arch/x86/kvm/i8254.c
> @@ -333,7 +333,7 @@ static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
> struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
> s64 interval;
>
> - if (!irqchip_in_kernel(kvm) || ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
> + if (ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
> return;
>
> interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
> --
> 1.8.3.1
>
>
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