Re: [PATCH v6] KVM: x86: Add x2APIC "features" to control EOI broadcast suppression

[David Woodhouse]

On Fri, 2026-01-23 at 12:56 +0000, Khushit Shah wrote:
> 
> @@ -4931,6 +4933,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  		break;
>  	case KVM_CAP_X2APIC_API:
>  		r = KVM_X2APIC_API_VALID_FLAGS;
> +		if (kvm && !irqchip_split(kvm))
> +			r &= ~KVM_X2APIC_ENABLE_SUPPRESS_EOI_BROADCAST;
>  		break;
>  	case KVM_CAP_NESTED_STATE:
>  		r = kvm_x86_ops.nested_ops->get_state ?
> @@ -6748,11 +6752,24 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
>  		if (cap->args[0] & ~KVM_X2APIC_API_VALID_FLAGS)
>  			break;
>  
> +		if ((cap->args[0] & KVM_X2APIC_ENABLE_SUPPRESS_EOI_BROADCAST) &&
> +		    (cap->args[0] & KVM_X2APIC_DISABLE_SUPPRESS_EOI_BROADCAST))
> +			break;
> +
> +		if ((cap->args[0] & KVM_X2APIC_ENABLE_SUPPRESS_EOI_BROADCAST) &&
> +		    !irqchip_split(kvm))
> +			break;
> +
>  		if (cap->args[0] & KVM_X2APIC_API_USE_32BIT_IDS)

Is it possible to set KVM_X2APIC_ENABLE_SUPPRESS_EOI_BROADCAST and
*then* create the in-kernel I/O APIC?

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