Solaris on KVM/QEMU: WARNING rtls0: Failure resetting PHY

When running Solaris (both version 10 and 11) on a QEMU/KVM virtual host, the Solaris guest displays this warning just after starting the system:
WARNING rtls0: Failure resetting PHY.

Although the networking seems to work fine.

I have this network device model selected for the Solaris guest: rtl8139

See also:
http://www.linux-kvm.org/page/Guest_Support_Status#UNIX_Family:_Solaris.2FOpenSolaris