From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Sasha Levin <sashal@kernel.org>,
frankja@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com,
kvm@vger.kernel.org, linux-s390@vger.kernel.org
Subject: [PATCH MANUALSEL 5.4 2/4] KVM: s390: Cap KVM_CAP_NR_VCPUS by num_online_cpus()
Date: Tue, 23 Nov 2021 11:37:01 -0500 [thread overview]
Message-ID: <20211123163706.289562-2-sashal@kernel.org> (raw)
In-Reply-To: <20211123163706.289562-1-sashal@kernel.org>
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 b286818d8d54d..fa11b42683901 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -550,6 +550,8 @@ 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_S390_COW:
r = MACHINE_HAS_ESOP;
--
2.33.0
next prev parent reply other threads:[~2021-11-23 16:37 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-23 16:37 [PATCH MANUALSEL 5.4 1/4] KVM: selftests: Fix kvm_vm_free() in cr4_cpuid_sync and vmx_tsc_adjust tests Sasha Levin
2021-11-23 16:37 ` Sasha Levin [this message]
2021-11-23 16:37 ` [PATCH MANUALSEL 5.4 4/4] KVM: MIPS: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS Sasha Levin
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