From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH] x86/PV: hide features dependent on XSAVE when booted with "no-xsave" Date: Fri, 27 Nov 2015 15:05:45 +0000 Message-ID: <56587149.6010909@citrix.com> References: <5658471802000078000B9A27@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1a2Kas-0007YJ-3q for xen-devel@lists.xenproject.org; Fri, 27 Nov 2015 15:05:50 +0000 In-Reply-To: <5658471802000078000B9A27@prv-mh.provo.novell.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: Jan Beulich , xen-devel Cc: Keir Fraser List-Id: xen-devel@lists.xenproject.org On 27/11/15 11:05, Jan Beulich wrote: > ... or when the guest has the XSAVE feature hidden by CPUID policy. > Not doing so is at best confusing to guests. > > Signed-off-by: Jan Beulich These changes here are an improvement (so I don't object to taking them ahead of my fullblown levelling series), but they are incomplete. xsaveopt, xsavec, xsetbv1, xsaves, avx and mpx depend on xsave. fma, fma4, f16c, avx2 and xop depend on avx. My levelling series actually introduces a dependency tree to properly evaluate the knockon effects of disabling certain features. I am unsure whether it is worth your time to split xsave and avx here, but I certainly wouldn't recommend making it any finer-grained at this stage. ~Andrew