[PATCH v2 10/11] hw/openrisc: virt: pass random seed to fdt

[Stafford Horne]

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 is confirmed to successfully initialize the
RNG on Linux 5.19-rc2.

Cc: Stafford Horne <shorne@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>
---
 hw/openrisc/virt.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/openrisc/virt.c b/hw/openrisc/virt.c
index f1d1293eeb..a301d0d769 100644
--- a/hw/openrisc/virt.c
+++ b/hw/openrisc/virt.c
@@ -8,6 +8,7 @@
 
 #include "qemu/osdep.h"
 #include "qemu/error-report.h"
+#include "qemu/guest-random.h"
 #include "qapi/error.h"
 #include "cpu.h"
 #include "exec/address-spaces.h"
@@ -130,6 +131,7 @@ static void openrisc_create_fdt(OR1KVirtState *state,
     void *fdt;
     int cpu;
     char *nodename;
+    uint8_t rng_seed[32];
 
     fdt = state->fdt = create_device_tree(&state->fdt_size);
     if (!fdt) {
@@ -186,6 +188,10 @@ static void openrisc_create_fdt(OR1KVirtState *state,
         qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
     }
 
+    /* Pass seed to RNG. */
+    qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
+    qemu_fdt_setprop(fdt, "/chosen", "rng-seed", rng_seed, sizeof(rng_seed));
+
     /* Create aliases node for use by devices. */
     qemu_fdt_add_subnode(fdt, "/aliases");
 }
-- 
2.36.1