runqemu: add virtio block device

Implement new QB_DRIVE_TYPE="/dev/vdb" which fails back
to virtio block device emulated by qemu.
That is needed to support following qemu command line:
-drive id=disk0,file=%s,if=none,format=%s \
  -device virtio-blk-device,drive=disk0'

Real use case is arm64 emulation with qemu with atf+optee+uboot,
so that uboot driver sees this disk and able to load from it.

Signed-off-by: Maxim Uvarov <[email protected]>

scripts/runqemu

@@ -1187,6 +1187,9 @@ class BaseConfig(object):
                     elif drive_type.startswith("/dev/hd"):
                         logger.info('Using ide drive')
                         vm_drive = "-drive file=%s,format=%s" % (self.rootfs, rootfs_format)
+                    elif drive_type.startswith("/dev/vdb"):
+                        logger.info('Using block virtio drive');
+                        vm_drive = '-drive id=disk0,file=%s,if=none,format=%s -device virtio-blk-device,drive=disk0' % (self.rootfs, rootfs_format)
                     else:
                         # virtio might have been selected explicitly (just use it), or
                         # is used as fallback (then warn about that).