From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH v7 01/15] nEPT: Support LOAD_IA32_EFER entry/exit controls for L1 Date: Mon, 5 Aug 2013 15:05:51 +0300 Message-ID: <20130805120551.GF10891@redhat.com> References: <1375690040-5764-1-git-send-email-gleb@redhat.com> <1375690040-5764-2-git-send-email-gleb@redhat.com> <346584789.9552175.1375703334046.JavaMail.root@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Arthur Chunqi Li , kvm , Xiao Guangrong , Jun Nakajima , Yang Zhang To: Paolo Bonzini Return-path: Received: from mx1.redhat.com ([209.132.183.28]:60878 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751502Ab3HEMF6 (ORCPT ); Mon, 5 Aug 2013 08:05:58 -0400 Content-Disposition: inline In-Reply-To: <346584789.9552175.1375703334046.JavaMail.root@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, Aug 05, 2013 at 07:48:54AM -0400, Paolo Bonzini wrote: > > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > > > index e999dc7..27efa6a 100644 > > > --- a/arch/x86/kvm/vmx.c > > > +++ b/arch/x86/kvm/vmx.c > > > @@ -2198,7 +2198,8 @@ static __init void nested_vmx_setup_ctls_msrs(void) > > > #else > > > nested_vmx_exit_ctls_high = 0; > > > #endif > > > - nested_vmx_exit_ctls_high |= VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR; > > > + nested_vmx_exit_ctls_high |= (VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR | > > > + VM_EXIT_LOAD_IA32_EFER); > > > > Gleb, why we don't need to check whether host supports > > VM_EXIT_LOAD_IA32_EFER here, as what you noted in my > > VM_EXIT_LOAD_IA32_PAT patch? > > The host can also emulate VM_EXIT_LOAD_IA32_EFER using the > VM-exit MSR-load feature. If neither EFER save/load nor > MSR save/load are available, I believe you are right and > the feature should not be available in nested VMX. As far as I can tell MSR save/load is not optional. -- Gleb.