KVM: VMX: Add the deliver posted interrupt algorithm

Only deliver the posted interrupt when target vcpu is running
and there is no previous interrupt pending in pir.

Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index d197579..dbf74c9 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -318,6 +318,19 @@
 	return count;
 }
 
+void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir)
+{
+	u32 i, pir_val;
+	struct kvm_lapic *apic = vcpu->arch.apic;
+
+	for (i = 0; i <= 7; i++) {
+		pir_val = xchg(&pir[i], 0);
+		if (pir_val)
+			*((u32 *)(apic->regs + APIC_IRR + i * 0x10)) |= pir_val;
+	}
+}
+EXPORT_SYMBOL_GPL(kvm_apic_update_irr);
+
 static inline int apic_test_and_set_irr(int vec, struct kvm_lapic *apic)
 {
 	apic->irr_pending = true;