From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0CA87C432C0 for ; Fri, 22 Nov 2019 21:33:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D60252070E for ; Fri, 22 Nov 2019 21:33:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726705AbfKVVd1 (ORCPT ); Fri, 22 Nov 2019 16:33:27 -0500 Received: from mga12.intel.com ([192.55.52.136]:60195 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726089AbfKVVd0 (ORCPT ); Fri, 22 Nov 2019 16:33:26 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 22 Nov 2019 13:33:26 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,231,1571727600"; d="scan'208";a="210367928" Received: from yyu32-desk1.sc.intel.com ([10.144.153.205]) by orsmga003.jf.intel.com with ESMTP; 22 Nov 2019 13:33:25 -0800 Message-ID: Subject: Re: [PATCH 1/6] x86/fpu/xstate: Fix small issues before adding supervisor xstates From: Yu-cheng Yu To: Borislav Petkov Cc: "linux-kernel@vger.kernel.org" , "x86@kernel.org" , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Dave Hansen , "Luck, Tony" , Andy Lutomirski , Rik van Riel , "Shankar, Ravi V" , Sebastian Andrzej Siewior , "Yu, Fenghua" , Peter Zijlstra Date: Fri, 22 Nov 2019 13:22:37 -0800 In-Reply-To: <20191009155847.GE10395@zn.tnic> References: <20190925151022.21688-1-yu-cheng.yu@intel.com> <20190925151022.21688-2-yu-cheng.yu@intel.com> <20191009155847.GE10395@zn.tnic> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.1-2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2019-10-09 at 08:58 -0700, Borislav Petkov wrote: > On Wed, Sep 25, 2019 at 08:10:17AM -0700, Yu-cheng Yu wrote: > > In response to earlier comments, fix small issues before introducing XSAVES > > supervisor states: > > - Add spaces around '*'. > > - Fix comments of xfeature_is_supervisor(). > > - Replace ((u64)1 << 63) with XCOMP_BV_COMPACTED_FORMAT. > > > > No functional changes from this patch. > > > > Signed-off-by: Yu-cheng Yu > > Reviewed-by: Dave Hansen > > Reviewed-by: Tony Luck > > --- > > arch/x86/kernel/fpu/xstate.c | 15 ++++++--------- > > 1 file changed, 6 insertions(+), 9 deletions(-) > > > > diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c > > index e5cb67d67c03..b793fc2156b9 100644 > > --- a/arch/x86/kernel/fpu/xstate.c > > +++ b/arch/x86/kernel/fpu/xstate.c > > @@ -60,7 +60,7 @@ u64 xfeatures_mask __read_mostly; > > > > static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; > > static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; > > -static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8]; > > +static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask) * 8]; > > > > /* > > * The XSAVE area of kernel can be in standard or compacted format; > > @@ -110,12 +110,8 @@ EXPORT_SYMBOL_GPL(cpu_has_xfeatures); > > static int xfeature_is_supervisor(int xfeature_nr) > > { > > /* > > - * We currently do not support supervisor states, but if > > - * we did, we could find out like this. > > - * > > - * SDM says: If state component 'i' is a user state component, > > - * ECX[0] return 0; if state component i is a supervisor > > - * state component, ECX[0] returns 1. > > + * Extended State Enumeration Sub-leaves (EAX = 0DH, ECX = n, n > 1) > > + * returns ECX[0] set to (1) for a supervisor state. > > "... and cleared (0) for a user state." > > I believe it is is clearer this way. > > > */ > > u32 eax, ebx, ecx, edx; > > > > Since you're touching this function: make it return bool as it is used > in boolean context only and have it return simply: > > return ecx & 1; This implicitly converts a u32 to a bool. By looking at it, I think it should be OK, but wonder if anything overlooked? I would be happy to make this a separate patch. Yu-cheng