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=-10.3 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 54B11C433E0 for ; Fri, 29 Jan 2021 22:35:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F256961492 for ; Fri, 29 Jan 2021 22:35:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233520AbhA2Wfr (ORCPT ); Fri, 29 Jan 2021 17:35:47 -0500 Received: from mga06.intel.com ([134.134.136.31]:14537 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229683AbhA2Wfo (ORCPT ); Fri, 29 Jan 2021 17:35:44 -0500 IronPort-SDR: dHlICr/bBKjj/s6kKxzyPrmxQjDfeizy2EwZPRU2RWp7BtfsrcY6f4BI5H226Rcuxe9TwN/VY4 yuLIUPGw77rg== X-IronPort-AV: E=McAfee;i="6000,8403,9879"; a="242012800" X-IronPort-AV: E=Sophos;i="5.79,386,1602572400"; d="scan'208";a="242012800" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jan 2021 14:35:02 -0800 IronPort-SDR: 8bq6hIfAMNgX92hbK4qH5hwd3yObjl/bcMQWw41W0LvWjm/TbPqtXNvZDJ35ASTSZm5aUQZoW5 0tDrkCEfMImg== X-IronPort-AV: E=Sophos;i="5.79,386,1602572400"; d="scan'208";a="411753322" Received: from yyu32-mobl1.amr.corp.intel.com (HELO [10.212.73.214]) ([10.212.73.214]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jan 2021 14:35:01 -0800 Subject: Re: [NEEDS-REVIEW] [PATCH v18 05/25] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states To: Dave Hansen , 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 , Cyrill Gorcunov , 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 , Andrew Cooper References: <20210127212524.10188-1-yu-cheng.yu@intel.com> <20210127212524.10188-6-yu-cheng.yu@intel.com> <7793b36e-6386-3f2e-36ca-b7ca988a88c9@intel.com> From: "Yu, Yu-cheng" Message-ID: <43f264df-2f3a-ea4c-c737-85cdc6714bd8@intel.com> Date: Fri, 29 Jan 2021 14:35:01 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <7793b36e-6386-3f2e-36ca-b7ca988a88c9@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/29/2021 1:00 PM, Dave Hansen wrote: > On 1/27/21 1:25 PM, Yu-cheng Yu wrote: >> @@ -135,6 +135,8 @@ enum xfeature { >> #define XFEATURE_MASK_PT (1 << XFEATURE_PT_UNIMPLEMENTED_SO_FAR) >> #define XFEATURE_MASK_PKRU (1 << XFEATURE_PKRU) >> #define XFEATURE_MASK_PASID (1 << XFEATURE_PASID) >> +#define XFEATURE_MASK_CET_USER (1 << XFEATURE_CET_USER) >> +#define XFEATURE_MASK_CET_KERNEL (1 << XFEATURE_CET_KERNEL) >> #define XFEATURE_MASK_LBR (1 << XFEATURE_LBR) >> >> #define XFEATURE_MASK_FPSSE (XFEATURE_MASK_FP | XFEATURE_MASK_SSE) >> @@ -237,6 +239,23 @@ struct pkru_state { >> u32 pad; >> } __packed; >> >> +/* >> + * State component 11 is Control-flow Enforcement user states >> + */ >> +struct cet_user_state { >> + u64 user_cet; /* user control-flow settings */ >> + u64 user_ssp; /* user shadow stack pointer */ >> +}; > > Andy Cooper just mentioned on IRC about this nugget in the spec: > > XRSTORS on CET state will do reserved bit and canonicality > checks on the state in similar manner as done by the WRMSR to > these state elements. > > We're using copy_kernel_to_xregs_err(), so the #GP *should* be OK. > Could we prove this out in practice, please? > Do we want to verify that setting reserved bits in CET XSAVES states triggers GP? Then, yes, I just verified it again. Thanks for reminding. Do we have any particular case relating to this? -- Yu-cheng