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    Subject[PATCH v9 09/18] KVM: Define a new interface kvm_intr_is_single_vcpu()
    Date
    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@intel.com>
    ---
    v9:
    - Move kvm_intr_is_single_vcpu_fast() to lapic.c
    - Remove incorrect WARN_ON_ONCE()

    v8:
    - Some optimizations in kvm_intr_is_single_vcpu().
    - Expose kvm_intr_is_single_vcpu() so we can use it in vmx code.
    - Add kvm_intr_is_single_vcpu_fast() as the fast path to find
    the target vCPU for the single-destination interrupt

    arch/x86/include/asm/kvm_host.h | 3 +++
    arch/x86/kvm/irq_comm.c | 27 +++++++++++++++++++
    arch/x86/kvm/lapic.c | 59 +++++++++++++++++++++++++++++++++++++++++
    arch/x86/kvm/lapic.h | 2 ++
    4 files changed, 91 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..f86a0da 100644
    --- a/arch/x86/kvm/irq_comm.c
    +++ b/arch/x86/kvm/irq_comm.c
    @@ -297,6 +297,33 @@ 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;
    +
    + if (kvm_intr_is_single_vcpu_fast(kvm, irq, dest_vcpu))
    + return true;
    +
    + 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;
    +
    + if (++r == 2)
    + return false;
    +
    + *dest_vcpu = vcpu;
    + }
    +
    + return r == 1;
    +}
    +EXPORT_SYMBOL_GPL(kvm_intr_is_single_vcpu);
    +
    #define IOAPIC_ROUTING_ENTRY(irq) \
    { .gsi = irq, .type = KVM_IRQ_ROUTING_IRQCHIP, \
    .u.irqchip = { .irqchip = KVM_IRQCHIP_IOAPIC, .pin = (irq) } }
    diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
    index 2a5ca97..3c8fc71 100644
    --- a/arch/x86/kvm/lapic.c
    +++ b/arch/x86/kvm/lapic.c
    @@ -764,6 +764,65 @@ out:
    return ret;
    }

    +bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq,
    + struct kvm_vcpu **dest_vcpu)
    +{
    + struct kvm_apic_map *map;
    + bool ret = false;
    + struct kvm_lapic *dst = NULL;
    +
    + if (irq->shorthand)
    + return false;
    +
    + rcu_read_lock();
    + map = rcu_dereference(kvm->arch.apic_map);
    +
    + if (!map)
    + goto out;
    +
    + if (irq->dest_mode == APIC_DEST_PHYSICAL) {
    + if (irq->dest_id == 0xFF)
    + goto out;
    +
    + if (irq->dest_id >= ARRAY_SIZE(map->phys_map))
    + goto out;
    +
    + dst = map->phys_map[irq->dest_id];
    + if (dst && kvm_apic_present(dst->vcpu))
    + *dest_vcpu = dst->vcpu;
    + else
    + goto out;
    + } else {
    + u16 cid;
    + unsigned long bitmap = 1;
    + int i, r = 0;
    +
    + if (!kvm_apic_logical_map_valid(map))
    + goto out;
    +
    + apic_logical_id(map, irq->dest_id, &cid, (u16 *)&bitmap);
    +
    + if (cid >= ARRAY_SIZE(map->logical_map))
    + goto out;
    +
    + for_each_set_bit(i, &bitmap, 16) {
    + dst = map->logical_map[cid][i];
    + if (++r == 2)
    + goto out;
    + }
    +
    + if (dst && kvm_apic_present(dst->vcpu))
    + *dest_vcpu = dst->vcpu;
    + else
    + goto out;
    + }
    +
    + ret = true;
    +out:
    + rcu_read_unlock();
    + return ret;
    +}
    +
    /*
    * Add a pending IRQ into lapic.
    * Return 1 if successfully added and 0 if discarded.
    diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
    index 7195274..032fe2d 100644
    --- a/arch/x86/kvm/lapic.h
    +++ b/arch/x86/kvm/lapic.h
    @@ -169,4 +169,6 @@ bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector);

    void wait_lapic_expire(struct kvm_vcpu *vcpu);

    +bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq,
    + struct kvm_vcpu **dest_vcpu);
    #endif
    --
    2.1.0


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