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

[Bin Meng]

On Mon, Jun 13, 2022 at 8:08 PM Jason A. Donenfeld <Jason@zx2c4.com> 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: Alistair Francis <alistair.francis@wdc.com>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
>  hw/riscv/virt.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
> index bc424dd2f5..368a723bf6 100644
> --- a/hw/riscv/virt.c
> +++ b/hw/riscv/virt.c
> @@ -21,6 +21,7 @@
>  #include "qemu/osdep.h"
>  #include "qemu/units.h"
>  #include "qemu/error-report.h"
> +#include "qemu/guest-random.h"
>  #include "qapi/error.h"
>  #include "hw/boards.h"
>  #include "hw/loader.h"
> @@ -998,6 +999,7 @@ static void create_fdt(RISCVVirtState *s, const 
> MemMapEntry *memmap,
>      MachineState *mc = MACHINE(s);
>      uint32_t phandle = 1, irq_mmio_phandle = 1, msi_pcie_phandle = 1;
>      uint32_t irq_pcie_phandle = 1, irq_virtio_phandle = 1;
> +    uint8_t rng_seed[32];
>
>      if (mc->dtb) {
>          mc->fdt = load_device_tree(mc->dtb, &s->fdt_size);
> @@ -1046,6 +1048,10 @@ update_bootargs:
>      if (cmdline && *cmdline) {
>          qemu_fdt_setprop_string(mc->fdt, "/chosen", "bootargs", cmdline);
>      }
> +
> +    /* Pass seed to RNG. */

nits: please remove the ending period

> +    qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
> +    qemu_fdt_setprop(mc->fdt, "/chosen", "rng-seed", rng_seed, 
> sizeof(rng_seed));
>  }
>
>  static inline DeviceState *gpex_pcie_init(MemoryRegion *sys_mem,
> --

Otherwise,
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>