Re: [PATCH v7 03/17] KVM: Define a new interface kvm_intr_is_single_vcpu()

[Paolo Bonzini]

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 
> ---
>  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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[PATCH v7 03/17] KVM: Define a new interface kvm_intr_is_single_vcpu()

[Feng Wu]

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...@intel.com
---
 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++;
+   *dest_vcpu = vcpu;
+   }
+
+   if (r == 1)
+   return true;
+   else
+   return false;
+}
+
 #define IOAPIC_ROUTING_ENTRY(irq) \
{ .gsi = irq, .type = KVM_IRQ_ROUTING_IRQCHIP,  \
  .u.irqchip = { .irqchip = KVM_IRQCHIP_IOAPIC, .pin = (irq) } }
-- 
2.1.0

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