Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934946AbcKWX2w (ORCPT ); Wed, 23 Nov 2016 18:28:52 -0500 Received: from mail-qk0-f175.google.com ([209.85.220.175]:33538 "EHLO mail-qk0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934507AbcKWX2u (ORCPT ); Wed, 23 Nov 2016 18:28:50 -0500 MIME-Version: 1.0 In-Reply-To: References: <1479863680-117511-1-git-send-email-dmatlack@google.com> <1479863680-117511-4-git-send-email-dmatlack@google.com> <1168524783.1374944.1479891977484.JavaMail.zimbra@redhat.com> From: David Matlack Date: Wed, 23 Nov 2016 15:28:18 -0800 Message-ID: Subject: Re: [PATCH 3/4] KVM: nVMX: accurate emulation of MSR_IA32_CR{0,4}_FIXED1 To: Paolo Bonzini Cc: kvm list , "linux-kernel@vger.kernel.org" , Jim Mattson , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 784 Lines: 16 On Wed, Nov 23, 2016 at 2:11 PM, Paolo Bonzini wrote: > On 23/11/2016 23:07, David Matlack wrote: >> A downside of this scheme is we'd have to remember to update >> nested_vmx_cr4_fixed1_update() before giving VMs new CPUID bits. If we >> forget, a VM could end up with different values for CR{0,4}_FIXED0 for >> the same CPUID depending on which version of KVM you're running on. > > If userspace doesn't obey KVM_GET_SUPPORTED_CPUID, all bets are off > anyway, so I don't think it's a big deal. However, if you want to make > it generated by userspace, that would be fine as well! Ok let's generate them in userspace. > That would simply entail removing this patch, wouldn't it? Mostly. The first half of the patch (initialize from host MSRs) should stay.