vDPA: report virtio-blk flush info to user space

This commit reports whether a virtio-blk device
support cache flush command to user space
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Message-Id: <20240218185606.13509-11-lingshan.zhu@intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/vdpa.c

@@ -1095,6 +1095,17 @@ static int vdpa_dev_blk_ro_config_fill(struct sk_buff *msg, u64 features)
 	return 0;
 }
 
+static int vdpa_dev_blk_flush_config_fill(struct sk_buff *msg, u64 features)
+{
+	u8 flush;
+
+	flush = ((features & BIT_ULL(VIRTIO_BLK_F_FLUSH)) == 0) ? 0 : 1;
+	if (nla_put_u8(msg, VDPA_ATTR_DEV_BLK_CFG_FLUSH, flush))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
 static int vdpa_dev_blk_config_fill(struct vdpa_device *vdev,
 				    struct sk_buff *msg)
 {
@@ -1136,6 +1147,9 @@ static int vdpa_dev_blk_config_fill(struct vdpa_device *vdev,
 	if (vdpa_dev_blk_ro_config_fill(msg, features_device))
 		return -EMSGSIZE;
 
+	if (vdpa_dev_blk_flush_config_fill(msg, features_device))
+		return -EMSGSIZE;
+
 	return 0;
 }
 

include/uapi/linux/vdpa.h

@@ -71,6 +71,7 @@ enum vdpa_attr {
 	VDPA_ATTR_DEV_BLK_CFG_MAX_WRITE_ZEROES_SEC,	/* u32 */
 	VDPA_ATTR_DEV_BLK_CFG_MAX_WRITE_ZEROES_SEG,	/* u32 */
 	VDPA_ATTR_DEV_BLK_CFG_READ_ONLY,		/* u8 */
+	VDPA_ATTR_DEV_BLK_CFG_FLUSH,		/* u8 */
 
 	/* new attributes must be added above here */
 	VDPA_ATTR_MAX,