From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 3/8] KVM: Activate fpu on clts Date: Sun, 24 Jan 2010 09:20:13 +0200 Message-ID: <4B5BF4AD.8090802@redhat.com> References: <1264080712-3981-1-git-send-email-avi@redhat.com> <1264080712-3981-4-git-send-email-avi@redhat.com> <20100123185606.GC24943@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Marcelo Tosatti Return-path: Received: from mx1.redhat.com ([209.132.183.28]:25307 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932069Ab0AXHUa (ORCPT ); Sun, 24 Jan 2010 02:20:30 -0500 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o0O7KS10004873 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Sun, 24 Jan 2010 02:20:29 -0500 In-Reply-To: <20100123185606.GC24943@amt.cnet> Sender: kvm-owner@vger.kernel.org List-ID: On 01/23/2010 08:56 PM, Marcelo Tosatti wrote: > On Thu, Jan 21, 2010 at 03:31:47PM +0200, Avi Kivity wrote: > >> Assume that if the guest executes clts, it knows what it's doing, and load the >> guest fpu to prevent an #NM exception. >> >> Signed-off-by: Avi Kivity >> --- >> > Out of curiosity, previously you assumed lazy activation on clts was a > win. Why undo it? > It wasn't so much assuming it's a win, it's more I was too lazy to find out. But it was easy to see from the traces that clts is often followed by #NM. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.