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

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Message-ID: <10f010ca-b79f-4886-ba18-3013560905b2@mixaill.net>
Date: Wed, 12 Mar 2025 16:17:52 +0300
From: Mikhail Paulyshka <me@...aill.net>
To: Borislav Petkov <bp@...en8.de>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org, Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH 0/2] x86/rdrand: implement sanity check for RDSEED

On 3/12/25 3:40 PM, Borislav Petkov wrote:
> On Wed, Mar 12, 2025 at 03:31:28PM +0300, 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.
> What's the microcode level on that machine?
> dmesg | grep -i microcode [ 0.059689] [ T0] Zenbleed: please update your microcode for the most 
optimal fix [ 0.663746] [ T1] microcode: Current revision: 0x08407007
> Also, send
>
> cpuid -r

https://paste.debian.net/1362645