kvm: Remove x2apic feature from CPU model when kernel_irqchip is off

x2apic feature is in the kvm_default_props and automatically added to all
CPU models when KVM is enabled. But userspace devices don't support x2apic
which can't be enabled without the in-kernel irqchip. It will trigger
warning of "host doesn't support requested feature: CPUID.01H:ECX.x2apic
[bit 21]" when kernel_irqchip is off. This patch is to fix it via removing
x2apic feature when kernel_irqchip is off.
Signed-off-by: NLan Tianyu <tianyu.lan@intel.com>
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>

target-i386/cpu.c

@@ -2132,6 +2132,10 @@ static void x86_cpu_load_def(X86CPU *cpu, X86CPUDefinition *def, Error **errp)
 
     /* Special cases not set in the X86CPUDefinition structs: */
     if (kvm_enabled()) {
+        if (!kvm_irqchip_in_kernel()) {
+            x86_cpu_change_kvm_default("x2apic", "off");
+        }
+
         x86_cpu_apply_props(cpu, kvm_default_props);
     }