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.

I'd do the same for other MIPS platforms but boston is the only one that
seems to use FDT.

Cc: Paul Burton <paulburton@kernel.org>
Cc: Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>
Cc: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 hw/mips/boston.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/mips/boston.c b/hw/mips/boston.c
index 1debca18ec..d2ab9da1a0 100644
--- a/hw/mips/boston.c
+++ b/hw/mips/boston.c
@@ -34,6 +34,7 @@
 #include "hw/qdev-properties.h"
 #include "qapi/error.h"
 #include "qemu/error-report.h"
+#include "qemu/guest-random.h"
 #include "qemu/log.h"
 #include "chardev/char.h"
 #include "sysemu/device_tree.h"
@@ -363,6 +364,7 @@ static const void *boston_fdt_filter(void *opaque, const void *fdt_orig,
     size_t ram_low_sz, ram_high_sz;
     size_t fdt_sz = fdt_totalsize(fdt_orig) * 2;
     g_autofree void *fdt = g_malloc0(fdt_sz);
+    uint8_t rng_seed[32];
 
     err = fdt_open_into(fdt_orig, fdt, fdt_sz);
     if (err) {
@@ -370,6 +372,9 @@ static const void *boston_fdt_filter(void *opaque, const void *fdt_orig,
         return NULL;
     }
 
+    qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
+    qemu_fdt_setprop(fdt, "/chosen", "rng-seed", rng_seed, sizeof(rng_seed));
+
     cmdline = (machine->kernel_cmdline && machine->kernel_cmdline[0])
             ? machine->kernel_cmdline : " ";
     err = qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
-- 
2.35.1