Enable virtio for tests

lib/cros_vm_lib.sh

 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 # Common vm functions for use in crosutils.
 
 DEFINE_string kvm_pid "" \
   "Use this pid file.  If it exists and is set, use the vm specified by pid."
 DEFINE_boolean no_graphics ${FLAGS_FALSE} "Runs the KVM instance silently."
 DEFINE_boolean persist "${FLAGS_FALSE}" "Persist vm."
@@ skipping 37 matching lines @@
     fi
 
     if [ ${FLAGS_snapshot} -eq ${FLAGS_TRUE} ]; then
       snapshot="-snapshot"
     fi
 
     sudo kvm -m 1024 \
       -vga std \
       -pidfile "${KVM_PID_FILE}" \
       -daemonize \
-      -net nic,model=e1000 \
+      -net nic,model=virtio \
       ${nographics} \
       ${snapshot} \
       -net user,hostfwd=tcp::${FLAGS_ssh_port}-:22 \
       -hda "${1}"
 
     LIVE_VM_IMAGE="${1}"
   fi
 }
 
 # Checks to see if we can access the target virtual machine with ssh.
@@ skipping 30 matching lines @@
     if [ -n "${pid}" ]; then
       echo "Killing ${pid}" >&2
       sudo kill ${pid}
       sudo rm "${KVM_PID_FILE}"
     else
       echo "No kvm pid found to stop." >&2
       return 1
     fi
   fi
 }