hw/microblaze: pass random seed to fdt

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.

Reviewed-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>

hw/microblaze/boot.c

@@ -30,6 +30,7 @@
 #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"
@@ -75,6 +76,7 @@ static int microblaze_load_dtb(hwaddr addr,
     int fdt_size;
     void *fdt = NULL;
     int r;
+    uint8_t rng_seed[32];
 
     if (dtb_filename) {
         fdt = load_device_tree(dtb_filename, &fdt_size);
@@ -83,6 +85,9 @@ static int microblaze_load_dtb(hwaddr addr,
         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);