From: "Jason A. Donenfeld" <Jason@zx2c4.com>

If the FDT contains /chosen/rng-seed, then the Linux RNG will use it to
initialize early. Set this using the usual guest random number
generation function. This FDT node is part of the DT specification.

Cc: Chris Wulff <crwulff@gmail.com>
Cc: Marek Vasut <marex@denx.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Message-Id: <20220719120113.118034-1-Jason@zx2c4.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/nios2/boot.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/nios2/boot.c b/hw/nios2/boot.c
index 07b8d87633..21cbffff47 100644
--- a/hw/nios2/boot.c
+++ b/hw/nios2/boot.c
@@ -34,6 +34,7 @@
 #include "qemu/option.h"
 #include "qemu/config-file.h"
 #include "qemu/error-report.h"
+#include "qemu/guest-random.h"
 #include "sysemu/device_tree.h"
 #include "sysemu/reset.h"
 #include "hw/boards.h"
@@ -83,6 +84,7 @@ static int nios2_load_dtb(struct nios2_boot_info bi, const uint32_t ramsize,
     int fdt_size;
     void *fdt = NULL;
     int r;
+    uint8_t rng_seed[32];
 
     if (dtb_filename) {
         fdt = load_device_tree(dtb_filename, &fdt_size);
@@ -91,6 +93,9 @@ static int nios2_load_dtb(struct nios2_boot_info bi, const uint32_t ramsize,
         return 0;
     }
 
+    qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
+    qemu_fdt_setprop(fdt, "/chosen", "rng-seed", rng_seed, sizeof(rng_seed));
+
     if (kernel_cmdline) {
         r = qemu_fdt_setprop_string(fdt, "/chosen", "bootargs",
                                     kernel_cmdline);
-- 
2.36.1