[RFC 1/4] vDPA/ifcvf: add get/set_vq_endian support for vDPA

[Zhu Lingshan <lingshan.zhu@intel.com>]

This commit introuduces new config operatoions for vDPA:
vdpa_config_ops.get_vq_endian: set vq endian-ness
vdpa_config_ops.set_vq_endian: get vq endian-ness

Because the endian-ness is a device wide attribute,
so seting a vq's endian-ness will result in changing
the device endian-ness, including all vqs and the config space.

These two operations are implemented in ifcvf in this commit.

Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
---
 drivers/vdpa/ifcvf/ifcvf_base.h |  1 +
 drivers/vdpa/ifcvf/ifcvf_main.c | 15 +++++++++++++++
 include/linux/vdpa.h            | 13 +++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
index f5563f665cc6..640238b95033 100644
--- a/drivers/vdpa/ifcvf/ifcvf_base.h
+++ b/drivers/vdpa/ifcvf/ifcvf_base.h
@@ -19,6 +19,7 @@
 #include <uapi/linux/virtio_blk.h>
 #include <uapi/linux/virtio_config.h>
 #include <uapi/linux/virtio_pci.h>
+#include <uapi/linux/vhost.h>
 
 #define N3000_DEVICE_ID		0x1041
 #define N3000_SUBSYS_DEVICE_ID	0x001A
diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
index f9c0044c6442..270637d0f3a5 100644
--- a/drivers/vdpa/ifcvf/ifcvf_main.c
+++ b/drivers/vdpa/ifcvf/ifcvf_main.c
@@ -684,6 +684,19 @@ static struct vdpa_notification_area ifcvf_get_vq_notification(struct vdpa_devic
 	return area;
 }
 
+static u8 ifcvf_vdpa_get_vq_endian(struct vdpa_device *vdpa_dev, u16 idx)
+{
+	return VHOST_VRING_LITTLE_ENDIAN;
+}
+
+static int ifcvf_vdpa_set_vq_endian(struct vdpa_device *vdpa_dev, u16 idx, u8 endian)
+{
+	if (endian != VHOST_VRING_LITTLE_ENDIAN)
+		return -EFAULT;
+
+	return 0;
+}
+
 /*
  * IFCVF currently doesn't have on-chip IOMMU, so not
  * implemented set_map()/dma_map()/dma_unmap()
@@ -715,6 +728,8 @@ static const struct vdpa_config_ops ifc_vdpa_ops = {
 	.set_config	= ifcvf_vdpa_set_config,
 	.set_config_cb  = ifcvf_vdpa_set_config_cb,
 	.get_vq_notification = ifcvf_get_vq_notification,
+	.get_vq_endian	= ifcvf_vdpa_get_vq_endian,
+	.set_vq_endian	= ifcvf_vdpa_set_vq_endian,
 };
 
 static struct virtio_device_id id_table_net[] = {
diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
index d282f464d2f1..5eb83453ba86 100644
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h
@@ -174,6 +174,17 @@ struct vdpa_map_file {
  *				@idx: virtqueue index
  *				Returns int: irq number of a virtqueue,
  *				negative number if no irq assigned.
+ * @set_vq_endian:		set endian-ness for a virtqueue
+ *				@vdev: vdpa device
+ *				@idx: virtqueue index
+ *				@endian: the endian-ness to set,
+ *				can be VHOST_VRING_LITTLE_ENDIAN or VHOST_VRING_BIG_ENDIAN
+ *				Returns integer: success (0) or error (< 0)
+ * @get_vq_endian:		get the endian-ness of a virtqueue
+ *				@vdev: vdpa device
+ *				@idx: virtqueue index
+ *				Returns u8, the endian-ness of the virtqueue,
+ *				can be VHOST_VRING_LITTLE_ENDIAN or VHOST_VRING_BIG_ENDIAN
  * @get_vq_align:		Get the virtqueue align requirement
  *				for the device
  *				@vdev: vdpa device
@@ -306,6 +317,8 @@ struct vdpa_config_ops {
 	(*get_vq_notification)(struct vdpa_device *vdev, u16 idx);
 	/* vq irq is not expected to be changed once DRIVER_OK is set */
 	int (*get_vq_irq)(struct vdpa_device *vdev, u16 idx);
+	int (*set_vq_endian)(struct vdpa_device *vdev, u16 idx, u8 endian);
+	u8 (*get_vq_endian)(struct vdpa_device *vdev, u16 idx);
 
 	/* Device ops */
 	u32 (*get_vq_align)(struct vdpa_device *vdev);
-- 
2.31.1