linux-kernel - Re: [PATCH v2 1/1] x86/rdrand: disable RDSEED on AMD Cyan Skillfish

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Message-ID: <20250706170741.GAaGqtXT99yYVoEmCh@fat_crate.local>
Date: Sun, 6 Jul 2025 19:07:41 +0200
From: Borislav Petkov <bp@...en8.de>
To: Mikhail Paulyshka <me@...aill.net>
Cc: Mario Limonciello <mario.limonciello@....com>,
	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, Rik van Riel <riel@...riel.com>
Subject: Re: [PATCH v2 1/1] x86/rdrand: disable RDSEED on AMD Cyan Skillfish

On Sun, Jul 06, 2025 at 07:42:39PM +0300, Mikhail Paulyshka wrote:
> On 6/17/25 11:05 PM, Borislav Petkov wrote:
> > Does this one work too?
> 
> It works, however, there is another issue with the BC250 that appeared since
> Linux 6.15.
> 
> Commit 4afeb0ed1753ebcad93ee3b45427ce85e9c8ec40 ( x86/mm: Enable broadcast
> TLB invalidation for multi-threaded processes)[1], merged in Linux 6.15-rc1,
> breaks the device — it starts to oops and panic under any load [2].

Looks like it GPs because CR4.PCID == 0.

Looks weird, we need to check PCID support somewhere, it seems.

Ok, let's get a common code base - 6.15. Pls boot it, send me full dmesg
again, your .config and the output of

cpuid -1r

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette