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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id h1sm13176567pfk.124.2019.09.30.11.05.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Sep 2019 11:05:21 -0700 (PDT) Date: Mon, 30 Sep 2019 11:05:20 -0700 From: Kees Cook To: Borislav Petkov Cc: Linus Torvalds , Thomas Gleixner , "Ahmed S. Darwish" , LKML , Theodore Ts'o , Nicholas Mc Guire , the arch/x86 maintainers , Andy Lutomirski Subject: Re: x86/random: Speculation to the rescue Message-ID: <201909301054.4E4F12B6D7@keescook> References: <20190930061014.GC29694@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190930061014.GC29694@zn.tnic> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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