KVM: VMX: Respect interrupt window in big real mode

If an interrupt is pending, we need to stop emulation so we
can inject it.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 9d3f972..28c72da 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3582,8 +3582,17 @@
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	enum emulation_result err = EMULATE_DONE;
 	int ret = 1;
+	u32 cpu_exec_ctrl;
+	bool intr_window_requested;
+
+	cpu_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
+	intr_window_requested = cpu_exec_ctrl & CPU_BASED_VIRTUAL_INTR_PENDING;
 
 	while (!guest_state_valid(vcpu)) {
+		if (intr_window_requested
+		    && (kvm_get_rflags(&vmx->vcpu) & X86_EFLAGS_IF))
+			return handle_interrupt_window(&vmx->vcpu);
+
 		err = emulate_instruction(vcpu, 0, 0, 0);
 
 		if (err == EMULATE_DO_MMIO) {