hw/ppc: 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 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>

diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
index 757cfaa62f8a82fed2f31749e770c4361efb8e48..32495d012353c0621a7ea6f6d1398eb1d1a39524 100644 (file)
--- 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 9a5382d5270fd160c96c900eac7305d46441469a..3a5112899e4162208928fe210dbfc473a9a1c6cf 100644 (file)
--- 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"));
 }