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Date:   Wed, 20 Apr 2022 14:05:00 +0200
From:   Heiko Carstens <hca@linux.ibm.com>
To:     Pierre Morel <pmorel@linux.ibm.com>
Cc:     kvm@vger.kernel.org, linux-s390@vger.kernel.org,
        linux-kernel@vger.kernel.org, borntraeger@de.ibm.com,
        frankja@linux.ibm.com, cohuck@redhat.com, david@redhat.com,
        thuth@redhat.com, imbrenda@linux.ibm.com, gor@linux.ibm.com,
        wintera@linux.ibm.com, seiden@linux.ibm.com, nrb@linux.ibm.com
Subject: Re: [PATCH v8 1/2] s390x: KVM: guest support for topology function
Message-ID: <Yl/27Pz3pvARmIHn@osiris>
References: <20220420113430.11876-1-pmorel@linux.ibm.com>
 <20220420113430.11876-2-pmorel@linux.ibm.com>
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> +static inline bool kvm_s390_topology_changed(struct kvm_vcpu *vcpu)
> +{
> +	if (!test_kvm_facility(vcpu->kvm, 11))
> +		return false;
> +
> +	/* A new vCPU has been hotplugged */
> +	if (vcpu->arch.prev_cpu == S390_KVM_TOPOLOGY_NEW_CPU)
> +		return true;
> +
> +	/* The real CPU backing up the vCPU moved to another socket */
> +	if (cpumask_test_cpu(vcpu->cpu,
> +			     topology_core_cpumask(vcpu->arch.prev_cpu)))
> +		return true;
> +
> +	return false;
> +}

This seems to be wrong. I'd guess that you need

	if (cpumask_test_cpu(vcpu->cpu,
			     topology_core_cpumask(vcpu->arch.prev_cpu)))
-->		return false;
-->	return true;