From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH] x86: Control CR0 TS behavior using dev_na_ts_allowed Date: Tue, 18 Mar 2014 19:14:22 +0000 Message-ID: <53289B0E.9070900@citrix.com> References: <53266841.6090308@prgmr.com> <1395027059-26248-1-git-send-email-srn@prgmr.com> <5326C2820200007800124905@nat28.tlf.novell.com> <5327081D0200007800124BCD@nat28.tlf.novell.com> <53270137.7000600@eu.citrix.com> <5327041E.2000205@eu.citrix.com> <53288B71.8030703@prgmr.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WPzT4-0002Xn-Qu for xen-devel@lists.xenproject.org; Tue, 18 Mar 2014 19:14:31 +0000 In-Reply-To: <53288B71.8030703@prgmr.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Sarah Newman Cc: George Dunlap , David Vrabel , Jan Beulich , xen-devel , Boris Ostrovsky , Yanhai Zhu List-Id: xen-devel@lists.xenproject.org On 18/03/14 18:07, Sarah Newman wrote: > > The guest cannot enable or disable this behavior but it can detect the behavior using CPUID. I > considered making the behavior configurable from within the guest, but did not find a clean way of > implementing it since any decision should really happen very early in the boot process. Suggestions > on how to do this are welcome. Consider using an Xen ELF note feature (see public/elfnote.h and public/features.h). e.g., XENFEAT_nm_hardware_ts This would be a trivial one-liner to the kernel and would require no user configurable option in the toolstack and compatibility would be retained for guests needing the current ABI. David