KVM: nVMX: Fix virtual interrupt delivery injection

This patch fix bug reported in https://bugzilla.kernel.org/show_bug.cgi?id=73331,
after the patch http://www.spinics.net/lists/kvm/msg105230.html applied, there is
some progress and the L2 can boot up, however, slowly. The original idea of this
fix vid injection patch is from "Zhang, Yang Z" <yang.z.zhang@intel.com>.

Interrupt which delivered by vid should be injected to L1 by L0 if current is in
L1, or should be injected to L2 by L0 through the old injection way if L1 doesn't
have set External-interrupt exiting bit. The current logic doen't consider these
cases. This patch fix it by vid intr to L1 if current is L1 or L2 through old
injection way if L1 doen't have External-interrupt exiting bit set.
Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: "Zhang, Yang Z" <yang.z.zhang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

@@ -7130,7 +7130,26 @@ static void vmx_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr)
 	if (max_irr == -1)
 		return;
 
-	vmx_set_rvi(max_irr);
+	/*
+	 * If a vmexit is needed, vmx_check_nested_events handles it.
+	 */
+	if (is_guest_mode(vcpu) && nested_exit_on_intr(vcpu))
+		return;
+
+	if (!is_guest_mode(vcpu)) {
+		vmx_set_rvi(max_irr);
+		return;
+	}
+
+	/*
+	 * Fall back to pre-APICv interrupt injection since L2
+	 * is run without virtual interrupt delivery.
+	 */
+	if (!kvm_event_needs_reinjection(vcpu) &&
+	    vmx_interrupt_allowed(vcpu)) {
+		kvm_queue_interrupt(vcpu, max_irr, false);
+		vmx_inject_irq(vcpu);
+	}
 }
 
 static void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)