Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932612AbcK1W5k (ORCPT ); Mon, 28 Nov 2016 17:57:40 -0500 Received: from mail-qt0-f178.google.com ([209.85.216.178]:35385 "EHLO mail-qt0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755617AbcK1W5d (ORCPT ); Mon, 28 Nov 2016 17:57:33 -0500 MIME-Version: 1.0 In-Reply-To: References: <1479863680-117511-1-git-send-email-dmatlack@google.com> <1479863680-117511-2-git-send-email-dmatlack@google.com> From: David Matlack Date: Mon, 28 Nov 2016 14:57:02 -0800 Message-ID: Subject: Re: [PATCH 1/4] KVM: nVMX: support restore of VMX capability MSRs 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: 1266 Lines: 31 On Mon, Nov 28, 2016 at 2:48 PM, Paolo Bonzini wrote: > On 28/11/2016 22:11, David Matlack wrote: >> > PINBASED_CTLS, PROCBASED_CTLS, EXIT_CTLS and ENTRY_CTLS can be derived >> > from their "true" counterparts, so I think it's better to remove the >> > "non-true" ones from struct nested_vmx (and/or add the "true" ones when >> > missing) and make them entirely computed. But it can be done on top. >> >> Good point. And that would mean userspace does not need to restore the >> non-true MSRs, right? > > Yes, sorry for being a bit too concise. :) I'll include this cleanup in the next version of the patchset since it affects which MSRs userspace will restore. It looks like a pretty simple patch. > >> KVM does not emulate MSR_IA32_VMX_BASIC[55]=0, >> and will probably never want to. > > That's a separate question, MSR_IA32_VMX_BASIC[55]=0 basically means > that the "true" capabilities are the same as the "default" capabilities. > If userspace wanted to set it that way, KVM right now would not hide > the "true" capability MSR, but on the other hand the nested hypervisor > should not even notice the difference. KVM would also need to use the non-true MSR in place of the true MSRs when checking VMCS12 during VM-entry. > > Paolo