alinux: virtio_ring: Support using kernel booting paramter when compiled as module

Commit 6f1e39b2(eci: drivers/virtio: add vring_force_dma_api boot param)
only supports using vring_force_dma_api when virtio_ring built into
kernel not as a module. But by default, virtio_ring is compiled as a
module, this patch adds support for that case. So users can specify
virtio_ring.vring_force_dma_api=1/0 in kernel booting paramter to turn
on/off this feature.
Signed-off-by: NShannon Zhao <shannon.zhao@linux.alibaba.com>
Reviewed-by: NZou Cao <zou.cao@linux.alibaba.com>

drivers/virtio/virtio_ring.c

@@ -24,6 +24,7 @@
 #include <linux/module.h>
 #include <linux/hrtimer.h>
 #include <linux/dma-mapping.h>
+#include <linux/moduleparam.h>
 #include <xen/xen.h>
 
 static bool vring_force_dma_api = false;
@@ -117,6 +118,9 @@ struct vring_virtqueue {
 
 #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
 
+#ifdef MODULE
+module_param(vring_force_dma_api, bool, 0640);
+#else
 static int __init vring_dma_api_setup(char *str)
 {
 	vring_force_dma_api = true;
@@ -125,6 +129,7 @@ static int __init vring_dma_api_setup(char *str)
 	return 0;
 }
 __setup("vring_force_dma_api", vring_dma_api_setup);
+#endif
 
 /*
  * Modern virtio devices have feature bits to specify whether they need a