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

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Message-ID: <20250312124006.GCZ9GApgQQ49dO_BMW@fat_crate.local>
Date: Wed, 12 Mar 2025 13:40:06 +0100
From: Borislav Petkov <bp@...en8.de>
To: Mikhail Paulyshka <me@...aill.net>
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 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?

Also, send

cpuid -r

output pls.

Thx.

-- 
Regards/Gruss,
    Boris.

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