KVM: deliver PIC interrupt only to vcpu0

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>

diff --git a/drivers/kvm/irq.c b/drivers/kvm/irq.c
index b88e50115588cfa8033d9f591a15af0f9d3972cc..7628c7ff628ff1db90f3a9a4d20df792bb59f4ad 100644 (file)
--- 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 f324cfb40084cd67f1e3316635c6f4836f733fc2..ec46a09e213562eeb1f99f554a0188aac0f2f24d 100644 (file)
--- 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 2706ec36c2586e24b32a2d95f2b64b0d9269904f..01e769672dccf7d0908a0d869fb8f07bfca58a8e 100644 (file)
--- 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;