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=-8.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 1B26DC433E7 for ; Mon, 12 Oct 2020 20:48:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id ADBBE2078E for ; Mon, 12 Oct 2020 20:48:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ADBBE2078E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 322AC940007; Mon, 12 Oct 2020 16:48:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2D230900002; Mon, 12 Oct 2020 16:48:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 14AE4940007; Mon, 12 Oct 2020 16:48:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0001.hostedemail.com [216.40.44.1]) by kanga.kvack.org (Postfix) with ESMTP id D35F5900002 for ; Mon, 12 Oct 2020 16:48:47 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 6CA3F181AE865 for ; Mon, 12 Oct 2020 20:48:47 +0000 (UTC) X-FDA: 77364462294.07.fire25_5509e75271fd Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin07.hostedemail.com (Postfix) with ESMTP id 534611803F9A2 for ; Mon, 12 Oct 2020 20:48:47 +0000 (UTC) X-HE-Tag: fire25_5509e75271fd X-Filterd-Recvd-Size: 4322 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Mon, 12 Oct 2020 20:48:45 +0000 (UTC) IronPort-SDR: KhVvqEL9/+NlTgyLFqiAudc3cbJSA2Z9oDVq6PcTAktl8Kb8Nf1iw1wXML4RpMhPKW0+anRAho fFBZVV2tY2Kg== X-IronPort-AV: E=McAfee;i="6000,8403,9772"; a="165862566" X-IronPort-AV: E=Sophos;i="5.77,367,1596524400"; d="scan'208";a="165862566" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Oct 2020 13:48:44 -0700 IronPort-SDR: H1g1CQHMtcwO1nWWiBZcdHpuTzPfruHJRRdh25uJeXaBoAYCtJIBhg3KVBUEXVaTG53rphSmVx fgUHljXAvRCA== X-IronPort-AV: E=Sophos;i="5.77,367,1596524400"; d="scan'208";a="356745959" Received: from yyu32-mobl1.amr.corp.intel.com (HELO [10.209.167.7]) ([10.209.167.7]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Oct 2020 13:48:43 -0700 Subject: Re: [PATCH v14 03/26] x86/fpu/xstate: Introduce CET MSR XSAVES supervisor states To: Cyrill Gorcunov Cc: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu References: <20201012153850.26996-1-yu-cheng.yu@intel.com> <20201012153850.26996-4-yu-cheng.yu@intel.com> <20201012195808.GD14048@grain> From: "Yu, Yu-cheng" Message-ID: Date: Mon, 12 Oct 2020 13:48:42 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <20201012195808.GD14048@grain> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 10/12/2020 12:58 PM, Cyrill Gorcunov wrote: > On Mon, Oct 12, 2020 at 08:38:27AM -0700, Yu-cheng Yu wrote: > ... >> /* >> * x86-64 Task Priority Register, CR8 >> diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c >> index 038e19c0019e..705fd9b94e31 100644 >> --- a/arch/x86/kernel/fpu/xstate.c >> +++ b/arch/x86/kernel/fpu/xstate.c >> @@ -38,6 +38,9 @@ static const char *xfeature_names[] = >> "Processor Trace (unused)" , >> "Protection Keys User registers", >> "unknown xstate feature" , >> + "Control-flow User registers" , >> + "Control-flow Kernel registers" , >> + "unknown xstate feature" , >> }; >> >> static short xsave_cpuid_features[] __initdata = { >> @@ -51,6 +54,9 @@ static short xsave_cpuid_features[] __initdata = { >> X86_FEATURE_AVX512F, >> X86_FEATURE_INTEL_PT, >> X86_FEATURE_PKU, >> + -1, /* Unused */ >> + X86_FEATURE_SHSTK, /* XFEATURE_CET_USER */ >> + X86_FEATURE_SHSTK, /* XFEATURE_CET_KERNEL */ >> }; > > Why do you need "-1" here in the array? The only 1:1 mapping is between > the names itselves and values, not indices of arrays so i don't understand > why we need this unused value. Sorry if it is a dumb questions and > been discussed already. > The indices are used indirectly in fpu__init_system_xstate() to set bits in xfeatures_mask_all, i.e. xfeatures_mask_all &= ~BIT_ULL(i). So they need to match the xstate feature bits. Yu-cheng