Do not drop global mutex for polled main loop runs If we call select without a timeout, it's more efficient to keep the global mutex locked as we may otherwise just play ping pong with a vcpu thread contending for it. This is particularly important for TCG mode where we run in lock-step with the vcpu thread. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>