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    Subject[PATCH 079/104] KVM: deliver PIC interrupt only to vcpu0
    Date
    From: Qing He <qing.he@intel.com>

    This patch changes the PIC interrupts delivery. Now it is only delivered
    to vcpu0 when either condition is met (on vcpu0):
    1. local APIC is hardware disabled
    2. LVT0 is unmasked and configured to delivery mode ExtInt

    It fixes the 2x faster wall clock on x86_64 and SMP i386 Linux guests

    Signed-off-by: Eddie (Yaozu) Dong <eddie.dong@intel.com>
    Signed-off-by: Qing He <qing.he@intel.com>
    Signed-off-by: Avi Kivity <avi@qumranet.com>
    ---
    drivers/kvm/irq.c | 15 ++++++++++-----
    drivers/kvm/irq.h | 1 +
    drivers/kvm/lapic.c | 17 +++++++++++++++++
    3 files changed, 28 insertions(+), 5 deletions(-)

    diff --git a/drivers/kvm/irq.c b/drivers/kvm/irq.c
    index b88e501..7628c7f 100644
    --- a/drivers/kvm/irq.c
    +++ b/drivers/kvm/irq.c
    @@ -33,8 +33,11 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *v)
    struct kvm_pic *s;

    if (kvm_apic_has_interrupt(v) == -1) { /* LAPIC */
    - s = pic_irqchip(v->kvm); /* PIC */
    - return s->output;
    + if (kvm_apic_accept_pic_intr(v)) {
    + s = pic_irqchip(v->kvm); /* PIC */
    + return s->output;
    + } else
    + return 0;
    }
    return 1;
    }
    @@ -50,9 +53,11 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v)

    vector = kvm_get_apic_interrupt(v); /* APIC */
    if (vector == -1) {
    - s = pic_irqchip(v->kvm);
    - s->output = 0; /* PIC */
    - vector = kvm_pic_read_irq(s);
    + if (kvm_apic_accept_pic_intr(v)) {
    + s = pic_irqchip(v->kvm);
    + s->output = 0; /* PIC */
    + vector = kvm_pic_read_irq(s);
    + }
    }
    return vector;
    }
    diff --git a/drivers/kvm/irq.h b/drivers/kvm/irq.h
    index f324cfb..ec46a09 100644
    --- a/drivers/kvm/irq.h
    +++ b/drivers/kvm/irq.h
    @@ -135,6 +135,7 @@ do { \

    void kvm_vcpu_kick(struct kvm_vcpu *vcpu);
    int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu);
    +int kvm_apic_accept_pic_intr(struct kvm_vcpu *vcpu);
    int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu);
    int kvm_create_lapic(struct kvm_vcpu *vcpu);
    void kvm_free_apic(struct kvm_lapic *apic);
    diff --git a/drivers/kvm/lapic.c b/drivers/kvm/lapic.c
    index 2706ec3..01e7696 100644
    --- a/drivers/kvm/lapic.c
    +++ b/drivers/kvm/lapic.c
    @@ -788,6 +788,8 @@ static void lapic_reset(struct kvm_vcpu *vcpu)

    for (i = 0; i < APIC_LVT_NUM; i++)
    apic_set_reg(apic, APIC_LVTT + 0x10 * i, APIC_LVT_MASKED);
    + apic_set_reg(apic, APIC_LVT0,
    + SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT));

    apic_set_reg(apic, APIC_DFR, 0xffffffffU);
    apic_set_reg(apic, APIC_SPIV, 0xff);
    @@ -932,6 +934,21 @@ int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu)
    return highest_irr;
    }

    +int kvm_apic_accept_pic_intr(struct kvm_vcpu *vcpu)
    +{
    + u32 lvt0 = apic_get_reg(vcpu->apic, APIC_LVT0);
    + int r = 0;
    +
    + if (vcpu->vcpu_id == 0) {
    + if (!apic_hw_enabled(vcpu->apic))
    + r = 1;
    + if ((lvt0 & APIC_LVT_MASKED) == 0 &&
    + GET_APIC_DELIVERY_MODE(lvt0) == APIC_MODE_EXTINT)
    + r = 1;
    + }
    + return r;
    +}
    +
    void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu)
    {
    struct kvm_lapic *apic = vcpu->apic;
    --
    1.5.3
    -
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