Re: [PATCH 3/4] KVM: i8254: remove unnecessary irqchip_in_kernel check
On 30/07/2015 06:36, Steve Rutherford wrote: > 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. You're right, and presumably it's also legal to create the PIT before KVM_CREATE_IRQCHIP. > Userspace might limit itself to > that scenario (PIT implies IOAPIC in-kernel), but that isn't enforced at PIT > creation. I'll play with the "PIT without IOAPIC" scenario and see if something breaks badly with this patch. From reading the code it seems like it should not introduce any problems (oopses or similar), but I'll set this patch aside for now. Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 3/4] KVM: i8254: remove unnecessary irqchip_in_kernel check
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 > --- > 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 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 3/4] KVM: i8254: remove unnecessary irqchip_in_kernel check
The PIT is only created if irqchip_in_kernel returns true, so the check is superfluous. Signed-off-by: Paolo Bonzini --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
