From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: Guest handling of IA32_DEBUGCTL MSR Date: Tue, 28 Apr 2015 14:00:31 +0200 Message-ID: <553F765F.4050008@siemens.com> References: <07377BC4-FD59-4A2E-9FA8-28ABE1B7F6D2@gmail.com> <553F7261.40500@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit To: Paolo Bonzini , Nadav Amit , kvm list Return-path: Received: from thoth.sbs.de ([192.35.17.2]:37126 "EHLO thoth.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965477AbbD1MAn (ORCPT ); Tue, 28 Apr 2015 08:00:43 -0400 In-Reply-To: <553F7261.40500@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Am 2015-04-28 um 13:43 schrieb Paolo Bonzini: > > > On 28/04/2015 13:42, Nadav Amit wrote: >> It seems strange that the guest is allowed to set IA32_DEBUGCTL MSR for the >> nested VM and get this value to the physical IA32_DEBUGCTL (see >> prepare_vmcs02), while it cannot set IA32_DEBUGCTL for itself (see >> kvm_set_msr_common). >> >> Am I missing something? > > No, it makes no sense. Are you sure that vmx is not allowing direct access to that MSR while in guest mode? We do save/restore it on all Intel CPUs, see setup_vmcs_config. Not sure about the AMD situation, though. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux