virtio: add virtio disk geometry feature

Rather than faking up some geometry, allow the backend to push the disk
geometry via virtio pci config option.  Keep the old geo code around for
compatibility.

Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (modified to single struct)

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h
index c75a9e82b924..d4695a3356d0 100644
--- a/include/linux/virtio_blk.h
+++ b/include/linux/virtio_blk.h
@@ -9,6 +9,7 @@
 #define VIRTIO_BLK_F_BARRIER    0       /* Does host support barriers? */
 #define VIRTIO_BLK_F_SIZE_MAX   1       /* Indicates maximum segment size */
 #define VIRTIO_BLK_F_SEG_MAX    2       /* Indicates maximum # of segments */
+#define VIRTIO_BLK_F_GEOMETRY   4       /* Legacy geometry available  */
 
 struct virtio_blk_config
 {
@@ -18,6 +19,12 @@ struct virtio_blk_config
         __le32 size_max;
         /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
         __le32 seg_max;
+        /* geometry the device (if VIRTIO_BLK_F_GEOMETRY) */
+        struct virtio_blk_geometry {
+                __le16 cylinders;
+                __u8 heads;
+                __u8 sectors;
+        } geometry;
 } __attribute__((packed));
 
 /* These two define direction. */