linux-kernel - Re: [PATCH 2/2] x86/random: Issue a warning if RDRAND or RDSEED fails

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Message-ID: <CAHmME9qEaJvaV2OVhpqPNnu4YmD-GgbqeePZPjZwA-XiHkeTmg@mail.gmail.com>
Date: Tue, 30 Jan 2024 19:23:07 +0100
From: "Jason A. Donenfeld" <Jason@...c4.com>
To: Dave Hansen <dave.hansen@...el.com>
Cc: "Reshetova, Elena" <elena.reshetova@...el.com>, 
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, 
	"x86@...nel.org" <x86@...nel.org>, "Theodore Ts'o" <tytso@....edu>, 
	Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>, 
	"Nakajima, Jun" <jun.nakajima@...el.com>, Tom Lendacky <thomas.lendacky@....com>, 
	"Kalra, Ashish" <ashish.kalra@....com>, Sean Christopherson <seanjc@...gle.com>, 
	"linux-coco@...ts.linux.dev" <linux-coco@...ts.linux.dev>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] x86/random: Issue a warning if RDRAND or RDSEED fails

On Tue, Jan 30, 2024 at 6:58 PM Dave Hansen <dave.hansen@...el.com> wrote:
>
> On 1/30/24 09:49, Jason A. Donenfeld wrote:
> >> Anybody disagree?
> > Yes, I disagree. I made a trivial test that shows RDSEED breaks easily
> > in a busy loop. So at the very least, your statement holds true only
> > for RDRAND.
>
> Well, darn. :)
>
> Any chance you could share some more information about the environment
> where you're seeing this?  It'd be good to reconcile what you're seeing
> with how the hardware is expected to behave.

That is already in this thread already. Maybe catch up on the whole
thing and then jump back in?
https://lore.kernel.org/all/Zbjw5hRHr_E6k18r@zx2c4.com/