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authorDavid Hildenbrand <dahi@linux.vnet.ibm.com>2015-11-06 12:08:48 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-12-09 14:31:26 -0500
commit7691b85a0295aafb1648da2caee75ada0f090033 (patch)
tree0697ba60e8e87d9210fbb1c2bfd22bbe64db23c7
parente8d097151d309eb71f750bbf34e6a7ef6256da7e (diff)
KVM: s390: enable SIMD only when no VCPUs were created
commit 5967c17b118a2bd1dd1d554cc4eee16233e52bec upstream. We should never allow to enable/disable any facilities for the guest when other VCPUs were already created. kvm_arch_vcpu_(load|put) relies on SIMD not changing during runtime. If somebody would create and run VCPUs and then decides to enable SIMD, undefined behaviour could be possible (e.g. vector save area not being set up). Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/s390/kvm/kvm-s390.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index e6729459fdb3..4a001c1b5a1a 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -289,12 +289,16 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
r = 0;
break;
case KVM_CAP_S390_VECTOR_REGISTERS:
- if (MACHINE_HAS_VX) {
+ mutex_lock(&kvm->lock);
+ if (atomic_read(&kvm->online_vcpus)) {
+ r = -EBUSY;
+ } else if (MACHINE_HAS_VX) {
set_kvm_facility(kvm->arch.model.fac->mask, 129);
set_kvm_facility(kvm->arch.model.fac->list, 129);
r = 0;
} else
r = -EINVAL;
+ mutex_unlock(&kvm->lock);
break;
case KVM_CAP_S390_USER_STSI:
kvm->arch.user_stsi = 1;