From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: GET_RNG_SEED hypercall ABI? (Re: [PATCH v5 0/5] random,x86,kvm: Rework arch RNG seeds and get some from kvm) Date: Wed, 27 Aug 2014 00:07:32 -0700 Message-ID: <53FD83B4.1030507@zytor.com> References: <53FD81F5.6030701@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: X86 ML , Theodore Ts'o , Kees Cook , kvm list , Konrad Rzeszutek Wilk , Gleb Natapov , Andrew Honig , Haiyang Zhang , Raghavendra K T , "linux-kernel@vger.kernel.org" , Srivatsa Vaddagiri , Daniel Borkmann , Bandan Das , Alok Kataria , virtualization@lists.linux-foundation.org To: Paolo Bonzini , Andy Lutomirski Return-path: In-Reply-To: <53FD81F5.6030701@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: kvm.vger.kernel.org On 08/27/2014 12:00 AM, Paolo Bonzini wrote: > Il 27/08/2014 01:58, Andy Lutomirski ha scritto: >> hpa pointed out that the ABI that I chose (an MSR from the KVM range >> and a KVM cpuid bit) is unnecessarily KVM-specific. It would be nice >> to allocate an MSR that everyone involved can agree on and, rather >> than relying on a cpuid bit, just have the guest probe for the MSR. >> >> This leads to a few questions: >> >> 1. How do we allocate an MSR? (For background, this would be an MSR >> that either returns 64 bits of best-effort cryptographically secure >> random data or fails with #GP.) > > Ask Intel? :) I'm going to poke around internally. Intel might as a matter of policy be reluctant to assign an MSR index specifically for software use, but I'll try to find out. -hpa