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From: Kees Cook <keescook@chromium.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Ahmed S. Darwish" <darwish.07@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Theodore Ts'o <tytso@mit.edu>,
	Nicholas Mc Guire <hofrat@opentech.at>,
	the arch/x86 maintainers <x86@kernel.org>,
	Andy Lutomirski <luto@kernel.org>
Subject: Re: x86/random: Speculation to the rescue
Date: Mon, 30 Sep 2019 11:05:20 -0700
Message-ID: <201909301054.4E4F12B6D7@keescook> (raw)
In-Reply-To: <20190930061014.GC29694@zn.tnic>

On Mon, Sep 30, 2019 at 08:10:15AM +0200, Borislav Petkov wrote:
> On Sun, Sep 29, 2019 at 07:59:19PM -0700, Linus Torvalds wrote:
> > All my smoke testing looked fine - I disabled trusting the CPU, I
> > increased the required entropy a lot, and to actually trigger the
> > lockup issue without the broken user space, I made /dev/urandom do
> > that "wait for entropy" thing too.
> 
> Hohum, seems to get rid of the longish delay during boot on my test
> boxes here:

Yes; for me too. This makes a huge difference in my ARM emulation
environments (where I wasn't using virtio-rng-device). Those VMs were
very boot entropy starved -- I was waiting minutes for sshd to start.

I doubt running something like dieharder on urandom would actually show
any deficiencies, but I've started a test up anyway. I'll yell in a few
hours if it actually has something bad to say. :)

-- 
Kees Cook

  parent reply index

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-28 22:24 Thomas Gleixner
2019-09-28 23:53 ` Linus Torvalds
2019-09-29  7:40   ` Thomas Gleixner
2019-09-29  8:05   ` Alexander E. Patrakov
2019-09-30  1:16   ` Linus Torvalds
2019-09-30  2:59     ` Linus Torvalds
2019-09-30  6:10       ` Borislav Petkov
2019-09-30 16:06         ` Linus Torvalds
2019-10-01 13:51           ` Borislav Petkov
2019-10-01 17:14             ` Linus Torvalds
2019-10-01 17:50               ` [PATCH] char/random: Add a newline at the end of the file Borislav Petkov
2019-09-30 18:05         ` Kees Cook [this message]
2019-09-30  3:37     ` x86/random: Speculation to the rescue Theodore Y. Ts'o
2019-09-30 13:16       ` Theodore Y. Ts'o
2019-09-30 16:15         ` Linus Torvalds
2019-09-30 16:32           ` Peter Zijlstra
2019-09-30 17:03             ` Linus Torvalds
2019-10-01 10:28           ` David Laight
2019-10-15 21:50             ` Thomas Gleixner
2019-10-01 16:15   ` Ahmed S. Darwish
2019-10-01 16:37     ` Kees Cook
2019-10-01 17:18       ` Ahmed S. Darwish
2019-10-01 17:25     ` Linus Torvalds
2019-10-06 12:07       ` Pavel Machek
2019-10-02 12:01     ` Theodore Y. Ts'o
2019-10-06 11:41   ` Pavel Machek
2019-10-06 17:26     ` Linus Torvalds
2019-10-06 17:35       ` Pavel Machek
2019-10-06 18:06         ` Linus Torvalds
2019-10-06 18:21           ` Pavel Machek
2019-10-06 18:26             ` Linus Torvalds
2019-10-07 11:47             ` Theodore Y. Ts'o
2019-10-07 22:18               ` Pavel Machek
2019-10-08 11:33                 ` David Laight
2019-10-09  8:02                   ` Pavel Machek
2019-10-09  9:37                     ` David Laight
2019-10-01  2:14 hgntkwis

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