[Xen-devel] [PATCH 5/6] tools/libxc: add DECLARE_HYPERCALL_BUFFER_SHADOW()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

From: David Vrabel <david.vrabel@xxxxxxxxxx>

DECLARE_HYPERCALL_BUFFER_SHADOW() is like DECLARE_HYPERCALL_BUFFER()
except it is backed by an already allocated hypercall buffer.

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 tools/libxc/xenctrl.h |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
index 400f0df..b55d857 100644
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -266,6 +266,24 @@ typedef struct xc_hypercall_buffer xc_hypercall_buffer_t;
     }
 
 /*
+ * Like DECLARE_HYPERCALL_BUFFER() but using an already allocated
+ * hypercall buffer, _hbuf.
+ *
+ * Useful when a hypercall buffer is passed to a function and access
+ * via the user pointer is required.
+ *
+ * See DECLARE_HYPERCALL_BUFFER_ARGUMENT() if the user pointer is not
+ * required.
+ */
+#define DECLARE_HYPERCALL_BUFFER_SHADOW(_type, _name, _hbuf)   \
+    _type *_name = _hbuf->hbuf;                                \
+    xc_hypercall_buffer_t XC__HYPERCALL_BUFFER_NAME(_name) = { \
+        .hbuf = (void *)-1,                                    \
+        .param_shadow = _hbuf,                                 \
+        HYPERCALL_BUFFER_INIT_NO_BOUNCE                        \
+    }
+
+/*
  * Declare the necessary data structure to allow a hypercall buffer
  * passed as an argument to a function to be used in the normal way.
  */
-- 
1.7.10.4


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