From mboxrd@z Thu Jan 1 00:00:00 1970 From: Borislav Petkov Subject: Re: [PATCH 3/6] x86: Add support for the clwb instruction Date: Tue, 11 Nov 2014 20:54:38 +0100 Message-ID: <20141111195438.GO31490@pd.tnic> References: <1415731396-19364-1-git-send-email-ross.zwisler@linux.intel.com> <1415731396-19364-4-git-send-email-ross.zwisler@linux.intel.com> <20141111191239.GC31523@pd.tnic> <1415735332.21508.1.camel@theros.lm.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mail.skyhub.de (mail.skyhub.de [78.46.96.112]) by gabe.freedesktop.org (Postfix) with ESMTP id 91B1A6E190 for ; Tue, 11 Nov 2014 11:54:43 -0800 (PST) Content-Disposition: inline In-Reply-To: <1415735332.21508.1.camel@theros.lm.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Ross Zwisler Cc: x86@kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Thomas Gleixner , H Peter Anvin , Ingo Molnar List-Id: dri-devel@lists.freedesktop.org T24gVHVlLCBOb3YgMTEsIDIwMTQgYXQgMTI6NDg6NTJQTSAtMDcwMCwgUm9zcyBad2lzbGVyIHdy b3RlOgo+IEVzc2VudGlhbGx5IHdlIG5lZWQgb25lIGFkZGl0aW9uYWwgYnl0ZSBhdCB0aGUgYmVn aW5uaW5nIG9mIHRoZSBjbGZsdXNoIHNvCj4gdGhhdCB3ZSBjYW4gZmxpcCBpdCBpbnRvIGEgY2xm bHVzaG9wdCBieSBjaGFuZ2luZyB0aGF0IGJ5dGUgaW50byBhIDB4NjYKPiBwcmVmaXguICBUd28g b3B0aW9ucyBhcmUgdG8gZWl0aGVyIGluc2VydCBhIDEgYnl0ZSBBU01fTk9QMSwgb3IgdG8gYWRk IGEgMQo+IGJ5dGUgTk9QX0RTX1BSRUZJWC4gIEJvdGggaGF2ZSBubyBmdW5jdGlvbmFsIGVmZmVj dCB3aXRoIHRoZSBwbGFpbiBjbGZsdXNoLAo+IGJ1dCBJJ3ZlIGJlZW4gdG9sZCB0aGF0IGV4ZWN1 dGluZyBhIGNsZmx1c2ggKyBwcmVmaXggc2hvdWxkIGJlIGZhc3RlciB0aGFuCj4gZXhlY3V0aW5n IGEgY2xmbHVzaCArIE5PUC4KCkkgc2VlLiA6KQoKVGhhbmtzLgoKLS0gClJlZ2FyZHMvR3J1c3Ms CiAgICBCb3Jpcy4KClNlbnQgZnJvbSBhIGZhdCBjcmF0ZSB1bmRlciBteSBkZXNrLiBGb3JtYXR0 aW5nIGlzIGZpbmUuCi0tCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fCmRyaS1kZXZlbCBtYWlsaW5nIGxpc3QKZHJpLWRldmVsQGxpc3RzLmZyZWVkZXNrdG9w Lm9yZwpodHRwOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vZHJpLWRl dmVsCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752111AbaKKTyp (ORCPT ); Tue, 11 Nov 2014 14:54:45 -0500 Received: from mail.skyhub.de ([78.46.96.112]:53707 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751644AbaKKTyo (ORCPT ); Tue, 11 Nov 2014 14:54:44 -0500 Date: Tue, 11 Nov 2014 20:54:38 +0100 From: Borislav Petkov To: Ross Zwisler Cc: linux-kernel@vger.kernel.org, H Peter Anvin , Ingo Molnar , Thomas Gleixner , David Airlie , dri-devel@lists.freedesktop.org, x86@kernel.org Subject: Re: [PATCH 3/6] x86: Add support for the clwb instruction Message-ID: <20141111195438.GO31490@pd.tnic> References: <1415731396-19364-1-git-send-email-ross.zwisler@linux.intel.com> <1415731396-19364-4-git-send-email-ross.zwisler@linux.intel.com> <20141111191239.GC31523@pd.tnic> <1415735332.21508.1.camel@theros.lm.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1415735332.21508.1.camel@theros.lm.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 11, 2014 at 12:48:52PM -0700, Ross Zwisler wrote: > Essentially we need one additional byte at the beginning of the clflush so > that we can flip it into a clflushopt by changing that byte into a 0x66 > prefix. Two options are to either insert a 1 byte ASM_NOP1, or to add a 1 > byte NOP_DS_PREFIX. Both have no functional effect with the plain clflush, > but I've been told that executing a clflush + prefix should be faster than > executing a clflush + NOP. I see. :) Thanks. -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. --