[PATCH MANUALSEL 4.14 1/3] KVM: s390: Cap KVM_CAP_NR_VCPUS by num_online_cpus()
From: Sasha Levin <sashal@kernel.org>
Date: 2021-11-23 16:38:05
Also in:
linux-s390, lkml, stable
Subsystem:
kernel virtual machine for s390 (kvm/s390), s390 architecture, the rest · Maintainers:
Christian Borntraeger, Janosch Frank, Claudio Imbrenda, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds
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 <redacted> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com> Message-Id: [ref] 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 05bd517528450..bc74a3056ac72 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c@@ -445,6 +445,8 @@ 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;
--
2.33.0