[XEN PATCH v1] libxl/arm: provide guests with random seed

[Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>]

Pass random seed via FDT, so that guests' CRNGs are better seeded early at boot.
Depending on its configuration Linux can use the seed as device randomness
or to just quickly initialize CRNG.
In either case this will provide extra randomness to further harden CRNG.

Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>
---
 tools/libxl/libxl_arm.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/libxl/libxl_arm.c b/tools/libxl/libxl_arm.c
index 34f8a29056..05c58a428c 100644
--- a/tools/libxl/libxl_arm.c
+++ b/tools/libxl/libxl_arm.c
@@ -342,6 +342,12 @@ static int make_chosen_node(libxl__gc *gc, void *fdt, bool 
ramdisk,
         if (res) return res;
     }
 
+    uint8_t seed[128];
+    res = libxl__random_bytes(gc, seed, sizeof(seed));
+    if (res) return res;
+    res = fdt_property(fdt, "rng-seed", seed, sizeof(seed));
+    if (res) return res;
+
     res = fdt_end_node(fdt);
     if (res) return res;
 
-- 
2.25.1