[Qemu-devel] [PATCH] Qemu/KVM: Remove x2apic feature from CPU model when kernel_irqchip is off

[Lan Tianyu <tianyu.lan@intel.com>]

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: Lan Tianyu <tianyu.lan@intel.com>
---
 target-i386/cpu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index c78f824..298fb62 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -2125,6 +2125,10 @@ 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);
     }
 
-- 
1.9.3