On 25/08/2015 10:50, Feng Wu wrote:
> This patch defines a new interface kvm_intr_is_single_vcpu(),
> which can returns whether the interrupt is for single-CPU or not.
>
> It is used by VT-d PI, since now we only support single-CPU
> interrupts, For lowest-priority interrupts, if user configures
> it via /proc/irq or uses irqbalance to make it single-CPU, we
> can use PI to deliver the interrupts to it. Full functionality
> of lowest-priority support will be added later.
>
> Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 3 +++
> arch/x86/kvm/irq_comm.c | 24 ++++++++++++++++++++++++
> 2 files changed, 27 insertions(+)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 49ec903..af11bca 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1204,4 +1204,7 @@ int __x86_set_memory_region(struct kvm *kvm,
> int x86_set_memory_region(struct kvm *kvm,
> const struct kvm_userspace_memory_region *mem);
>
> +bool kvm_intr_is_single_vcpu(struct kvm *kvm, struct kvm_lapic_irq *irq,
> + struct kvm_vcpu **dest_vcpu);
> +
> #endif /* _ASM_X86_KVM_HOST_H */
> diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
> index 9efff9e..a9572a13 100644
> --- a/arch/x86/kvm/irq_comm.c
> +++ b/arch/x86/kvm/irq_comm.c
> @@ -297,6 +297,30 @@ out:
> return r;
> }
>
> +bool kvm_intr_is_single_vcpu(struct kvm *kvm, struct kvm_lapic_irq *irq,
> + struct kvm_vcpu **dest_vcpu)
> +{
> + int i, r = 0;
> + struct kvm_vcpu *vcpu;
> +
> + kvm_for_each_vcpu(i, vcpu, kvm) {
> + if (!kvm_apic_present(vcpu))
> + continue;
> +
> + if (!kvm_apic_match_dest(vcpu, NULL, irq->shorthand,
> + irq->dest_id, irq->dest_mode))
> + continue;
> +
> + r++;
if (++r == 2)
return false;
> + *dest_vcpu = vcpu;
> + }
> +
> + if (r == 1)
> + return true;
> + else
> + return false;
... then just "return r == 1;" is enough here.
This could also be optimized to treat APIC_DEST_NOSHORT specially. Get
the mda, and if it has a single physical CPU check that it has
kvm_apic_present(vcpu) set. Otherwise fall back to the slow path.
Paolo
> +}
> +
> #define IOAPIC_ROUTING_ENTRY(irq) \
> { .gsi = irq, .type = KVM_IRQ_ROUTING_IRQCHIP, \
> .u.irqchip = { .irqchip = KVM_IRQCHIP_IOAPIC, .pin = (irq) } }
>
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