From: Vitaly Kuznetsov vkuznets@redhat.com

[ Upstream commit 82cc27eff4486f8e79ef8faac1af1f5573039aa4 ]

KVM_CAP_NR_VCPUS is a legacy advisory value which on other architectures return num_online_cpus() caped by KVM_CAP_NR_VCPUS or something else (ppc and arm64 are special cases). On s390, KVM_CAP_NR_VCPUS returns the same as KVM_CAP_MAX_VCPUS and this may turn out to be a bad 'advice'. Switch s390 to returning caped num_online_cpus() too.

Acked-by: Christian Borntraeger borntraeger@de.ibm.com Signed-off-by: Vitaly Kuznetsov vkuznets@redhat.com Reviewed-by: Christian Borntraeger borntraeger@linux.ibm.com Message-Id: 20211116163443.88707-6-vkuznets@redhat.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/kvm/kvm-s390.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index d8fd2eadcda7f..b8f67d19e132d 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -399,6 +399,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) r = KVM_MAX_VCPUS; else if (sclp.has_esca && sclp.has_64bscao) r = KVM_S390_ESCA_CPU_SLOTS; + if (ext == KVM_CAP_NR_VCPUS) + r = min_t(unsigned int, num_online_cpus(), r); break; case KVM_CAP_NR_MEMSLOTS: r = KVM_USER_MEM_SLOTS;