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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: x86@kernel.org, linux-coco@lists.linux.dev,
	linux-kernel@vger.kernel.org, "Borislav Petkov" <bp@alien8.de>,
	"Daniel P . Berrangé" <berrange@redhat.com>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Elena Reshetova" <elena.reshetova@intel.com>,
	"H . Peter Anvin" <hpa@zytor.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	"Theodore Ts'o" <tytso@mit.edu>,
	"Thomas Gleixner" <tglx@linutronix.de>
Subject: Re: [PATCH v3] x86/coco: Require seeding RNG with RDRAND on CoCo systems
Date: Thu, 22 Feb 2024 00:09:32 +0100	[thread overview]
Message-ID: <CAHmME9rCQgY_DMmpOEJWO8qytNw3ErJNy9L-E7WzEKYHVyqCHA@mail.gmail.com> (raw)
In-Reply-To: <7a8c04bb-214b-4031-bdd6-59dad62f88a7@intel.com>

On Wed, Feb 21, 2024 at 11:47 PM Dave Hansen <dave.hansen@intel.com> wrote:
> OK, so we're trying to get 256 bits of seed data from RDRAND?

Yes. This fills a 32-byte buffer of longs up with output from
arch_get_random_longs().

> But no pattern I could discern.  Did you mean something different by
> "platform drivers"?

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/um/kernel/um_arch.c#n413
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/char/random.c#n655
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/gcc-plugins/latent_entropy_plugin.c#n90


> If we're going to have arch/x86-specific crud, it would be great to make
> it obvious and straightforward to those of us simple folk that are
> familiar with arch/x86 code.

If you insist, I'll stick a local `enum { RANDOM_BYTES_COUNT = 32 }`
in that function or something. Seems unnecessary to me but if that's
what you need no problem. Would that suffice? Or a different variable
name? Or a comment on "what is 32 about?"

Jason

  reply	other threads:[~2024-02-21 23:09 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-21 12:32 [PATCH v3] x86/coco: Require seeding RNG with RDRAND on CoCo systems Jason A. Donenfeld
2024-02-21 14:34 ` Reshetova, Elena
2024-02-21 15:36 ` Jason A. Donenfeld
2024-02-21 15:37 ` Kirill A . Shutemov
2024-02-21 15:51 ` Theodore Ts'o
2024-02-21 16:55 ` Dave Hansen
2024-02-21 17:19   ` Jason A. Donenfeld
2024-02-21 22:47     ` Dave Hansen
2024-02-21 23:09       ` Jason A. Donenfeld [this message]
2024-02-21 23:35         ` Dave Hansen
2024-02-22  2:05           ` [PATCH v4] " Jason A. Donenfeld
2024-02-23 22:05             ` Tom Lendacky
2024-02-24  1:14               ` Jason A. Donenfeld
2024-02-24  1:18                 ` [PATCH v5] " Jason A. Donenfeld
2024-03-13 23:34                   ` Jason A. Donenfeld
2024-03-14 11:14                     ` Borislav Petkov
2024-03-26 11:21                   ` Borislav Petkov
2024-03-26 16:07                     ` [PATCH v6] " Jason A. Donenfeld
2024-03-28 15:13                       ` Tom Lendacky
2024-04-04  9:11                       ` [tip: x86/urgent] " tip-bot2 for Jason A. Donenfeld
2024-02-22  7:35       ` [PATCH v3] " Reshetova, Elena

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