Revert "qa/tasks/qemu: switch nbd devices from virtio to ide"

This reverts commit fa1bf21.

qa/tasks/qemu.py

@@ -204,21 +204,13 @@ def generate_iso(ctx, config):
                     'image_url' in disk:
                 continue
             dev_letter = disk['device_letter']
-            if disk['encryption_format'] == 'none':
-                link_dev_command = ':' # no-op
-            else:
-                # encrypted disks use IDE (/dev/sdX instead of /dev/vdX)
-                link_dev_command = \
-                    'ln -s /dev/sd{dev_letter} /dev/vd{dev_letter}'.format(
-                        dev_letter=dev_letter)
             user_data += """
 - |
   #!/bin/bash
   mkdir /mnt/test_{dev_letter}
-  {link_dev_command}
   mkfs -t xfs /dev/vd{dev_letter}
   mount -t xfs /dev/vd{dev_letter} /mnt/test_{dev_letter}
-""".format(dev_letter=dev_letter, link_dev_command=link_dev_command)
+""".format(dev_letter=dev_letter)
 
         user_data += """
 - |
@@ -504,23 +496,17 @@ def run_qemu(ctx, config):
                 continue
 
             if disk['encryption_format'] == 'none':
-                interface = 'virtio'
                 disk_spec = 'rbd:rbd/{img}:id={id}'.format(
                     img=disk['image_name'],
                     id=client[len('client.'):]
                     )
             else:
-                # encrypted disks use ide as a temporary workaround for
-                # a bug in qemu when using virtio over nbd
-                # TODO: use librbd encryption directly via qemu (not via nbd)
-                interface = 'ide'
                 disk_spec = disk['device_path']
 
             args.extend([
                 '-drive',
-                'file={disk_spec},format=raw,if={interface},cache={cachemode}'.format(
+                'file={disk_spec},format=raw,if=virtio,cache={cachemode}'.format(
                     disk_spec=disk_spec,
-                    interface=interface,
                     cachemode=cachemode,
                     ),
                 ])