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

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Message-ID: <aa6b15c8-45e9-47b7-8280-84cbacd9aa4c@mixaill.net>
Date: Wed, 19 Mar 2025 00:40:31 +0300
From: Mikhail Paulyshka <me@...aill.net>
To: Mario Limonciello <mario.limonciello@....com>,
 Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] x86/rdrand: implement sanity check for RDSEED

On 3/18/25 11:50 PM, Mario Limonciello wrote:
> 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,

#cat /sys/class/dmi/id/bios_version
P5.00

I have tried P4.00G and P5.00, both have the same microcode and behavior.