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>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/kvm/lapic.c b/drivers/kvm/lapic.c
index 2706ec36c258..01e769672dcc 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;