On Tue, Jan 08, 2013 at 01:39:31PM -0500, Christoffer Dall wrote:

+	/*
+	 * Check whether this vcpu requires the cache to be flushed on
+	 * this physical CPU. This is a consequence of doing dcache
+	 * operations by set/way on this vcpu. We do it here to be in
+	 * a non-preemptible section.
+	 */
+	if (cpumask_test_cpu(cpu, &vcpu->arch.require_dcache_flush)) {
+		cpumask_clear_cpu(cpu, &vcpu->arch.require_dcache_flush);

There is cpumask_test_and_clear_cpu() which may be better for this.