Re: [PATCH] hw/openrisc: pass random seed to fdt

[Jason A. Donenfeld]

On 6/13/22, Stafford Horne <shorne@gmail.com> wrote:
> On Sun, Jun 12, 2022 at 11:59:49PM +0200, Jason A. Donenfeld wrote:
>> 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>
>> ---
>>  hw/openrisc/openrisc_sim.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
>> index 35adce17ac..41821b5f30 100644
>> --- a/hw/openrisc/openrisc_sim.c
>> +++ b/hw/openrisc/openrisc_sim.c
>> @@ -20,6 +20,7 @@
>>
>>  #include "qemu/osdep.h"
>>  #include "qemu/error-report.h"
>> +#include "qemu/guest-random.h"
>>  #include "qapi/error.h"
>>  #include "cpu.h"
>>  #include "hw/irq.h"
>> @@ -115,6 +116,7 @@ static void openrisc_create_fdt(Or1ksimState *state,
>>      int cpu;
>>      char *nodename;
>>      int pic_ph;
>> +    uint8_t rng_seed[32];
>>
>>      fdt = state->fdt = create_device_tree(&state->fdt_size);
>>      if (!fdt) {
>> @@ -165,6 +167,10 @@ static void openrisc_create_fdt(Or1ksimState *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");
>>  }
>
> This all looks fine to me.  I will queue it with my current changes.  Since
> this
> is only applying to openrisc_sim I would like to also apply it to virt.  To
> do
> that I need to have a common core openrisc system creation api.  That way I
> don't end up copying and pasting this to every platform.

Sure. Or just do it on the virt board only if that's easier.

Jason