qemu/bswap: Add const_le64()

Gcc requires constant versions of cpu_to_le* calls.

Add a 64 bit version.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Gregory Price <gregory.price@memverge.com>
Tested-by: Gregory Price <gregory.price@memverge.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Message-Id: <20230206172816.8201-9-Jonathan.Cameron@huawei.com>
Reviewed-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

include/qemu/bswap.h

@@ -125,11 +125,20 @@ CPU_CONVERT(le, 32, uint32_t)
 CPU_CONVERT(le, 64, uint64_t)
 
 /*
- * Same as cpu_to_le{16,32}, except that gcc will figure the result is
+ * Same as cpu_to_le{16,32,64}, except that gcc will figure the result is
  * a compile-time constant if you pass in a constant.  So this can be
  * used to initialize static variables.
  */
 #if HOST_BIG_ENDIAN
+# define const_le64(_x)                          \
+    ((((_x) & 0x00000000000000ffU) << 56) |      \
+     (((_x) & 0x000000000000ff00U) << 40) |      \
+     (((_x) & 0x0000000000ff0000U) << 24) |      \
+     (((_x) & 0x00000000ff000000U) <<  8) |      \
+     (((_x) & 0x000000ff00000000U) >>  8) |      \
+     (((_x) & 0x0000ff0000000000U) >> 24) |      \
+     (((_x) & 0x00ff000000000000U) >> 40) |      \
+     (((_x) & 0xff00000000000000U) >> 56))
 # define const_le32(_x)                          \
     ((((_x) & 0x000000ffU) << 24) |              \
      (((_x) & 0x0000ff00U) <<  8) |              \
@@ -139,6 +148,7 @@ CPU_CONVERT(le, 64, uint64_t)
     ((((_x) & 0x00ff) << 8) |                    \
      (((_x) & 0xff00) >> 8))
 #else
+# define const_le64(_x) (_x)
 # define const_le32(_x) (_x)
 # define const_le16(_x) (_x)
 #endif