KVM: Keep an upper bound of initialized vcpus

That way, we don't need to loop for KVM_MAX_VCPUS for a single vcpu
vm.

Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 556416962541..4e1a017f3db7 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -2391,6 +2391,11 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
         if (r < 0)
                 goto out_free_vcpus;
 
+        spin_lock(&kvm_lock);
+        if (n >= kvm->nvcpus)
+                kvm->nvcpus = n + 1;
+        spin_unlock(&kvm_lock);
+
         return r;
 
 out_free_vcpus: