virtio 1.0 makes all memory structures LE, so
we need APIs to conditionally do a byteswap on BE
architectures.

To make it easier to check code statically,
add virtio specific types for multi-byte integers
in memory.

Add low level wrappers that do a byteswap conditionally, these will be
useful e.g. for vhost.  Add high level wrappers that
query device endian-ness and act accordingly.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/linux/virtio_byteorder.h  | 59 +++++++++++++++++++++++++++++++++++++++
 include/linux/virtio_config.h     | 32 +++++++++++++++++++++
 include/uapi/linux/virtio_ring.h  | 45 ++++++++++++++---------------
 include/uapi/linux/virtio_types.h | 48 +++++++++++++++++++++++++++++++
 include/uapi/linux/Kbuild         |  1 +
 5 files changed, 163 insertions(+), 22 deletions(-)
 create mode 100644 include/linux/virtio_byteorder.h
 create mode 100644 include/uapi/linux/virtio_types.h

diff --git a/include/linux/virtio_byteorder.h b/include/linux/virtio_byteorder.h
new file mode 100644
index 0000000..824ed0b
--- /dev/null
+++ b/include/linux/virtio_byteorder.h

@@ -0,0 +1,59 @@
+#ifndef _LINUX_VIRTIO_BYTEORDER_H
+#define _LINUX_VIRTIO_BYTEORDER_H
+#include <linux/types.h>
+#include <uapi/linux/virtio_types.h>
+
+/*
+ * Memory accessors for handling virtio in modern little endian and in

diff --git a/include/uapi/linux/virtio_types.h b/include/uapi/linux/virtio_types.h
new file mode 100644
index 0000000..b90385f
--- /dev/null
+++ b/include/uapi/linux/virtio_types.h

@@ -0,0 +1,48 @@
+#ifndef _UAPI_LINUX_VIRTIO_TYPES_H
+#define _UAPI_LINUX_VIRTIO_TYPES_H
+/* An interface for efficient virtio implementation, currently for use by KVM
+ * and lguest, but hopefully others soon.