1 files changed, 94 insertions, 0 deletions

diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
new file mode 100644
index 000000000000..c2d1fa4dc1ee
--- /dev/null
+++ b/include/xen/interface/io/blkif.h
@@ -0,0 +1,94 @@
+/******************************************************************************
+ * blkif.h
+ *
+ * Unified block-device I/O interface for Xen guest OSes.
+ *
+ * Copyright (c) 2003-2004, Keir Fraser
+ */
+
+#ifndef __XEN_PUBLIC_IO_BLKIF_H__
+#define __XEN_PUBLIC_IO_BLKIF_H__
+
+#include "ring.h"
+#include "../grant_table.h"
+
+/*
+ * Front->back notifications: When enqueuing a new request, sending a
+ * notification can be made conditional on req_event (i.e., the generic
+ * hold-off mechanism provided by the ring macros). Backends must set
+ * req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
+ *
+ * Back->front notifications: When enqueuing a new response, sending a
+ * notification can be made conditional on rsp_event (i.e., the generic
+ * hold-off mechanism provided by the ring macros). Frontends must set
+ * rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()).
+ */
+
+typedef uint16_t blkif_vdev_t;
+typedef uint64_t blkif_sector_t;
+
+/*
+ * REQUEST CODES.
+ */
+#define BLKIF_OP_READ              0
+#define BLKIF_OP_WRITE             1
+/*
+ * Recognised only if "feature-barrier" is present in backend xenbus info.
+ * The "feature_barrier" node contains a boolean indicating whether barrier
+ * requests are likely to succeed or fail. Either way, a barrier request
+ * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
+ * the underlying block-device hardware. The boolean simply indicates whether
+ * or not it is worthwhile for the frontend to attempt barrier requests.
+ * If a backend does not recognise BLKIF_OP_WRITE_BARRIER, it should *not*
+ * create the "feature-barrier" node!
+ */
+#define BLKIF_OP_WRITE_BARRIER     2
+
+/*
+ * Maximum scatter/gather segments per request.
+ * This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE.
+ * NB. This could be 12 if the ring indexes weren't stored in the same page.
+ */
+#define BLKIF_MAX_SEGMENTS_PER_REQUEST 11
+
+struct blkif_request {
+        uint8_t        operation;    /* BLKIF_OP_???                         */
+        uint8_t        nr_segments;  /* number of segments                   */
+        blkif_vdev_t   handle;       /* only for read/write requests         */
+        uint64_t       id;           /* private guest value, echoed in resp  */
+        blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
+        struct blkif_request_segment {
+                grant_ref_t gref;        /* reference to I/O buffer frame        */
+                /* @first_sect: first sector in frame to transfer (inclusive).   */
+                /* @last_sect: last sector in frame to transfer (inclusive).     */
+                uint8_t     first_sect, last_sect;
+        } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+};
+
+struct blkif_response {
+        uint64_t        id;              /* copied from request */
+        uint8_t         operation;       /* copied from request */
+        int16_t         status;          /* BLKIF_RSP_???       */
+};
+
+/*
+ * STATUS RETURN CODES.
+ */
+ /* Operation not supported (only happens on barrier writes). */
+#define BLKIF_RSP_EOPNOTSUPP  -2
+ /* Operation failed for some unspecified reason (-EIO). */
+#define BLKIF_RSP_ERROR       -1
+ /* Operation completed successfully. */
+#define BLKIF_RSP_OKAY         0
+
+/*
+ * Generate blkif ring structures and types.
+ */
+
+DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response);
+
+#define VDISK_CDROM        0x1
+#define VDISK_REMOVABLE    0x2
+#define VDISK_READONLY     0x4
+
+#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */