Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
include/linux/kvm_host.h | 4 ++++
virt/kvm/kvm_main.c | 2 ++
2 files changed, 6 insertions(+)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index bd1097a95704..81089cf1f0c1 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -427,6 +427,10 @@ struct kvm {
static inline struct kvm_vcpu *kvm_get_vcpu(struct kvm *kvm, int i)
{
+ /* Pairs with smp_wmb() in kvm_vm_ioctl_create_vcpu, in case
+ * the caller has read kvm->online_vcpus before (as is the case
+ * for kvm_for_each_vcpu, for example).
+ */
smp_rmb();
return kvm->vcpus[i];
}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8dc4828f623f..093b3d10b411 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2206,6 +2206,8 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
}
kvm->vcpus[atomic_read(&kvm->online_vcpus)] = vcpu;
+
+ /* Pairs with smp_rmb() in kvm_get_vcpu. */
smp_wmb();
atomic_inc(&kvm->online_vcpus);
--
1.8.3.1
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