From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH 1/1] virtio: rng: add derating factor for use by hwrng core Date: Mon, 11 Aug 2014 15:11:03 -0700 Message-ID: <53E93F77.9030305@linux.intel.com> References: <6f2df652355d6e78da846d06e32489b7d9cdfcc2.1407782982.git.amit.shah@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Rusty Russell , Virtualization List , kvm list , jgarzik@bitpay.com, duwe@lst.de, Amos Kong , ricardo.neri-calderon@linux.intel.com, tytso@mit.edu, herbert@gondor.apana.org.au To: Amit Shah , linux-kernel@vger.kernel.org Return-path: In-Reply-To: <6f2df652355d6e78da846d06e32489b7d9cdfcc2.1407782982.git.amit.shah@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 08/11/2014 11:49 AM, Amit Shah wrote: > The khwrngd thread is started when a hwrng device of sufficient > quality is registered. The virtio-rng device is backed by the > hypervisor, and we trust the hypervisor to provide real entropy. A > malicious hypervisor is a scenario that's ruled out, so we are certain > the quality of randomness we receive is perfectly trustworthy. Hence, > we use 100% for the factor, indicating maximum confidence in the source. > > Signed-off-by: Amit Shah It isn't "ruled out", it is just irrelevant: if the hypervisor is malicious, the quality of your random number source is the least of your problems. -hpa