libxencall: introduce variant of xencall2() returning long

Some hypercalls, memory-op in particular, can return values requiring
more than 31 bits to represent. Hence the underlying layers need to make
sure they won't truncate such values.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Ian Jackson <iwj@xenproject.org>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

tools/include/xencall.h

@@ -113,6 +113,10 @@ int xencall5(xencall_handle *xcall, unsigned int op,
              uint64_t arg1, uint64_t arg2, uint64_t arg3,
              uint64_t arg4, uint64_t arg5);
 
+/* Variant(s) of the above, as needed, returning "long" instead of "int". */
+long xencall2L(xencall_handle *xcall, unsigned int op,
+               uint64_t arg1, uint64_t arg2);
+
 /*
  * Allocate and free memory which is suitable for use as a pointer
  * argument to a hypercall.

tools/libs/call/core.c

@@ -127,6 +127,17 @@ int xencall2(xencall_handle *xcall, unsigned int op,
     return osdep_hypercall(xcall, &call);
 }
 
+long xencall2L(xencall_handle *xcall, unsigned int op,
+               uint64_t arg1, uint64_t arg2)
+{
+    privcmd_hypercall_t call = {
+        .op = op,
+        .arg = { arg1, arg2 },
+    };
+
+    return osdep_hypercall(xcall, &call);
+}
+
 int xencall3(xencall_handle *xcall, unsigned int op,
              uint64_t arg1, uint64_t arg2, uint64_t arg3)
 {

tools/libs/call/libxencall.map

@@ -27,3 +27,8 @@ VERS_1.2 {
 	global:
 		xencall_fd;
 } VERS_1.1;
+
+VERS_1.3 {
+	global:
+		xencall2L;
+} VERS_1.2;