From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760083Ab0EDSEm (ORCPT ); Tue, 4 May 2010 14:04:42 -0400 Received: from mga09.intel.com ([134.134.136.24]:39151 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757881Ab0EDSEk (ORCPT ); Tue, 4 May 2010 14:04:40 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.52,328,1270450800"; d="scan'208";a="618830732" Subject: Re: [PATCH 1/2] x86: eliminate TS_XSAVE From: Suresh Siddha Reply-To: Suresh Siddha To: Avi Kivity Cc: "Cui, Dexuan" , Sheng Yang , Ingo Molnar , "H. Peter Anvin" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" In-Reply-To: <1272812038-32484-2-git-send-email-avi@redhat.com> References: <1272812038-32484-1-git-send-email-avi@redhat.com> <1272812038-32484-2-git-send-email-avi@redhat.com> Content-Type: text/plain Organization: Intel Corp Date: Tue, 04 May 2010 11:03:29 -0700 Message-Id: <1272996209.2833.1.camel@sbs-t61.sc.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 (2.26.3-1.fc11) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2010-05-02 at 07:53 -0700, Avi Kivity wrote: > The fpu code currently uses current->thread_info->status & TS_XSAVE as > a way to distinguish between XSAVE capable processors and older processors. > The decision is not really task specific; instead we use the task status to > avoid a global memory reference - the value should be the same across all > threads. > > Eliminate this tie-in into the task structure by using an alternative > instruction keyed off the XSAVE cpu feature; this results in shorter and > faster code, without introducing a global memory reference. > > Signed-off-by: Avi Kivity Acked-by: Suresh Siddha