From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [patch] VMX Unrestricted mode support Date: Sun, 31 May 2009 10:23:07 -0500 Message-ID: <4A22A0DB.8050906@codemonkey.ws> References: <1243552292.25456.23.camel@mukti.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: avi@redhat.com, kvm@vger.kernel.org To: Nitin A Kamble Return-path: Received: from mail-ew0-f176.google.com ([209.85.219.176]:45238 "EHLO mail-ew0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752782AbZEaPXK (ORCPT ); Sun, 31 May 2009 11:23:10 -0400 Received: by ewy24 with SMTP id 24so7308932ewy.37 for ; Sun, 31 May 2009 08:23:10 -0700 (PDT) In-Reply-To: <1243552292.25456.23.camel@mukti.sc.intel.com> Sender: kvm-owner@vger.kernel.org List-ID: Nitin A Kamble wrote: > Avi, > > A new VMX feature "Unrestricted Guest" feature is added in the VMX > specification. You can look at the latest Intel processor manual for > details of the feature here: > > http://www.intel.com/products/processor/manuals > > It allows kvm guests to run real mode and unpaged mode > code natively in the VMX mode when EPT is turned on. With the > unrestricted guest there is no need to emulate the guest real mode code > in the vm86 container or in the emulator. Also the guest big real mode > code works like native. > > The attached patch enhances KVM to use the unrestricted guest feature > if available on the processor. It also adds a new kernel/module > parameter to disable the unrestricted guest feature at the boot time. > > Signed-Off-By: Nitin A Kamble > > Thanks & Regards, > Nitin > It may make sense to expose this as a CAP down to userspace. We could possibly make better error messages in userspace when we get an unknown vmexit failure on pre-wsm hardware. Regards, Anthony Liguori