runefivm: Use AIO and don't cache disk accesses

Host-side caching is silly, let's not do that.

Signed-off-by: Marc Zyngier <maz@kernel.org>
diff --git a/runefivm.sh b/runefivm.sh
index 7744ad9..330aaed 100755
--- a/runefivm.sh
+++ b/runefivm.sh
@@ -44,7 +44,7 @@
 fi
 
 if [ "$disk" != none ]; then
-	dskdev="-drive if=none,format=raw,file=$disk,id=disk0 \
+	dskdev="-drive if=none,format=raw,cache=none,aio=native,file=$disk,id=disk0 \
 		-device virtio-blk-$bus$virtio,drive=disk0"
 fi