xen: add a meaningful declaration of grant_copy_segment into xen_common.h

Currently the xen_disk source has to carry #ifdef exclusions to compile
against Xen older then 4.8. This is a bit messy so this patch lifts the
definition of struct xengnttab_grant_copy_segment and adds it into the
pre-4.8 compat area in xen_common.h, which allows xen_disk to be cleaned
up.
Signed-off-by: NPaul Durrant <paul.durrant@citrix.com>
Acked-by: NAnthony PERARD <anthony.perard@citrix.com>
Signed-off-by: NStefano Stabellini <sstabellini@kernel.org>

hw/block/xen_disk.c

@@ -496,8 +496,6 @@ static int ioreq_map(struct ioreq *ioreq)
     return 0;
 }
 
-#if CONFIG_XEN_CTRL_INTERFACE_VERSION >= 40800
-
 static void ioreq_free_copy_buffers(struct ioreq *ioreq)
 {
     int i;
@@ -579,22 +577,6 @@ static int ioreq_grant_copy(struct ioreq *ioreq)
 
     return rc;
 }
-#else
-static void ioreq_free_copy_buffers(struct ioreq *ioreq)
-{
-    abort();
-}
-
-static int ioreq_init_copy_buffers(struct ioreq *ioreq)
-{
-    abort();
-}
-
-static int ioreq_grant_copy(struct ioreq *ioreq)
-{
-    abort();
-}
-#endif
 
 static int ioreq_runio_qemu_aio(struct ioreq *ioreq);
 

include/hw/xen/xen_common.h

@@ -667,8 +667,21 @@ static inline int xen_domain_create(xc_interface *xc, uint32_t ssidref,
 
 #if CONFIG_XEN_CTRL_INTERFACE_VERSION < 40800
 
-
-typedef void *xengnttab_grant_copy_segment_t;
+struct xengnttab_grant_copy_segment {
+    union xengnttab_copy_ptr {
+        void *virt;
+        struct {
+            uint32_t ref;
+            uint16_t offset;
+            uint16_t domid;
+        } foreign;
+    } source, dest;
+    uint16_t len;
+    uint16_t flags;
+    int16_t status;
+};
+
+typedef struct xengnttab_grant_copy_segment xengnttab_grant_copy_segment_t;
 
 static inline int xengnttab_grant_copy(xengnttab_handle *xgt, uint32_t count,
                                        xengnttab_grant_copy_segment_t *segs)