KVM: Introduce kvm_vcpu_is_bsp() function.

Use it instead of open code "vcpu_id zero is BSP" assumption.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0d481b2..0d54ede 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1747,6 +1747,8 @@
 		goto vcpu_destroy;
 	}
 	kvm->vcpus[n] = vcpu;
+	if (n == 0)
+		kvm->bsp_vcpu = vcpu;
 	mutex_unlock(&kvm->lock);
 
 	/* Now it's all set up, let userspace reach it */