Reviewed-by: Sean Rhodes <sean@starlabs.systems>

On Tue, 25 Apr 2023 at 18:09, Benjamin Doron <benjamin.doron00@gmail.com>
wrote:

> From: Benjamin Doron <benjamin.doron@9elements.com>
>
> Presently, `ArchIsRngSupported()` always returns TRUE, per
>
> https://github.com/tianocore/edk2/blob/1eeca0750af5af2f0e78437bf791ac2de74bde74/MdePkg/Library/BaseRngLib/Rand/RdRand.c#L124-L125
> .
> Therefore, `BaseRngLibConstructor()` should continue to assert RDRAND
> support.
>
> However, older platforms do not support RDRAND, such as QEMU in some
> configurations. Therefore, define an RngLib library class for such
> systems, using a new flag. Maintain current behaviour by default.
>
> Note that this is less secure behaviour, and should be avoided in
> production.
>
> Cc: Guo Dong <guo.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Sean Rhodes <sean@starlabs.systems>
> Cc: James Lu <james.lu@intel.com>
> Cc: Gua Guo <gua.guo@intel.com>
> Signed-off-by: Benjamin Doron <benjamin.doron@9elements.com>
> ---
>  UefiPayloadPkg/UefiPayloadPkg.dsc | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/UefiPayloadPkg/UefiPayloadPkg.dsc
> b/UefiPayloadPkg/UefiPayloadPkg.dsc
> index 9847f189fff5..1e803ba01567 100644
> --- a/UefiPayloadPkg/UefiPayloadPkg.dsc
> +++ b/UefiPayloadPkg/UefiPayloadPkg.dsc
> @@ -130,6 +130,7 @@
>    # This is how BaseCpuTimerLib works, and a recommended way to get
> Frequence, so set the default value as TRUE.
>    # Note: for emulation platform such as QEMU, this may not work and
> should set it as FALSE
>    DEFINE CPU_TIMER_LIB_ENABLE  = TRUE
> +  DEFINE CPU_RNG_ENABLE        = TRUE
>
>    DEFINE MULTIPLE_DEBUG_PORT_SUPPORT = FALSE
>
> @@ -204,7 +205,11 @@
>  !endif
>    IntrinsicLib|CryptoPkg/Library/IntrinsicLib/IntrinsicLib.inf
>    OpensslLib|CryptoPkg/Library/OpensslLib/OpensslLib.inf
> +!if $(CPU_RNG_ENABLE) == TRUE
>    RngLib|MdePkg/Library/BaseRngLib/BaseRngLib.inf
> +!else
> +  RngLib|MdePkg/Library/BaseRngLibTimerLib/BaseRngLibTimerLib.inf
> +!endif
>    HobLib|UefiPayloadPkg/Library/DxeHobLib/DxeHobLib.inf
>
>    #
> --
> 2.39.2
>
>