Re: [PATCH 0/2] x86/rdrand: implement sanity check for RDSEED

[Mario Limonciello <mario.limonciello@amd.com>]

On 3/12/2025 07:31, Mikhail Paulyshka wrote:
> On the AMD Cyan Skillfish (Family 0x17 Model 0x47 Stepping 0x0), which
> is a Zen2-based APU found on the AMD BC-250 board, there is a situation
> where RDRAND works fine, but RDSEED generates FF. This leads to some
> applications that use RDSEED to generate random numbers (such as
> Qt and KDE) into a nearly unusable state.
> 
> Although AMD has fixed the Zen2 RDRAND issues in 2019 with a microcode update,
> no such update has been released for the Family 0x17 Model 0x47 core.
> 
> This patchset introduces an separate sanity check for RDSEED and hides the
> RDSEED and RDRAND from CPUID on AMD platforms in the case of a malfunction.
> 
> Mikhail Paulyshka (2):
>    x86/rdrand: implement sanity check for RDSEED
>    x86/rdrand: hide RDRAND and RDSEED from CPUID in case of a malfunction
> 
>   arch/x86/include/asm/archrandom.h      |  1 +
>   arch/x86/include/asm/msr-index.h       |  1 +
>   arch/x86/kernel/cpu/common.c           |  1 +
>   arch/x86/kernel/cpu/rdrand.c           | 48 ++++++++++++++++++++++++--
>   tools/arch/x86/include/asm/msr-index.h |  1 +
>   5 files changed, 49 insertions(+), 3 deletions(-)
> 

Can you please share more about the BIOS firmware version on your device?

/sys/class/dmi/id/bios_version

Thanks,