[PULL 06/30] hw/ppc: pass random seed to fdt

[Daniel Henrique Barboza <danielhb413@gmail.com>]

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-rc6. The rng-seed node is part of the DT spec. Set
this on the paravirt platforms, spapr and e500, just as is done on other
architectures with paravirt hardware.

Cc: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20220712135114.289855-1-Jason@zx2c4.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/e500.c  | 5 +++++
 hw/ppc/spapr.c | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
index 757cfaa62f..32495d0123 100644
--- a/hw/ppc/e500.c
+++ b/hw/ppc/e500.c
@@ -17,6 +17,7 @@
 #include "qemu/osdep.h"
 #include "qemu/datadir.h"
 #include "qemu/units.h"
+#include "qemu/guest-random.h"
 #include "qapi/error.h"
 #include "e500.h"
 #include "e500-ccsr.h"
@@ -346,6 +347,7 @@ static int ppce500_load_device_tree(PPCE500MachineState *pms,
         };
     const char *dtb_file = machine->dtb;
     const char *toplevel_compat = machine->dt_compatible;
+    uint8_t rng_seed[32];
 
     if (dtb_file) {
         char *filename;
@@ -403,6 +405,9 @@ static int ppce500_load_device_tree(PPCE500MachineState *pms,
     if (ret < 0)
         fprintf(stderr, "couldn't set /chosen/bootargs\n");
 
+    qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
+    qemu_fdt_setprop(fdt, "/chosen", "rng-seed", rng_seed, sizeof(rng_seed));
+
     if (kvm_enabled()) {
         /* Read out host's frequencies */
         clock_freq = kvmppc_get_clockfreq();
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 9a5382d527..3a5112899e 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -27,6 +27,7 @@
 #include "qemu/osdep.h"
 #include "qemu/datadir.h"
 #include "qemu/memalign.h"
+#include "qemu/guest-random.h"
 #include "qapi/error.h"
 #include "qapi/qapi-events-machine.h"
 #include "qapi/qapi-events-qdev.h"
@@ -1014,6 +1015,7 @@ static void spapr_dt_chosen(SpaprMachineState *spapr, void *fdt, bool reset)
 {
     MachineState *machine = MACHINE(spapr);
     SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(machine);
+    uint8_t rng_seed[32];
     int chosen;
 
     _FDT(chosen = fdt_add_subnode(fdt, 0, "chosen"));
@@ -1091,6 +1093,9 @@ static void spapr_dt_chosen(SpaprMachineState *spapr, void *fdt, bool reset)
         spapr_dt_ov5_platform_support(spapr, fdt, chosen);
     }
 
+    qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
+    _FDT(fdt_setprop(fdt, chosen, "rng-seed", rng_seed, sizeof(rng_seed)));
+
     _FDT(spapr_dt_ovec(fdt, chosen, spapr->ov5_cas, "ibm,architecture-vec-5"));
 }
 
-- 
2.36.1