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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A4E08C4332F for ; Fri, 11 Feb 2022 23:37:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354205AbiBKXhL (ORCPT ); Fri, 11 Feb 2022 18:37:11 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:40068 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239391AbiBKXhI (ORCPT ); Fri, 11 Feb 2022 18:37:08 -0500 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AFCF0D6A; Fri, 11 Feb 2022 15:37:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644622626; x=1676158626; h=message-id:date:mime-version:to:cc:references:from: subject:in-reply-to:content-transfer-encoding; bh=n+pCIpoYcPq/hU9tjTp1ZYglJMzSc25WZnIG3BnVpns=; b=RgsRGfeStggMFAnzh4MHkKCJCMOiBzZWnCG9hSYt6xP0Wnw1ynYmSpDQ 8X/iT42en14UY6k3Z2DUQKbxdvSOrcSF5CGfsz1CLIKYHtlYcPVzHlqZ8 zAdX8CLVPfmybMtms2zT+U9o8ILqD6vvxvJgpwcNcw8z6xH4bqympXa/2 VLTTyPVtiCS5+r6QZfc+HMngk3Opvxy6UVkfWRgaPUOyzhsLn+ODXcKLy lcEG/1CHAvKaOrzSLs0MEAxlpoBOmABJ8dFxPHD/qOfPAuLWUVfTR9BzD pUfbYUYg07TjPqMHulWl7p5JSi7QhWr5RqGC+Y/YkZ2pKGMZUkGE6CqN8 Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10255"; a="248660820" X-IronPort-AV: E=Sophos;i="5.88,361,1635231600"; d="scan'208";a="248660820" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Feb 2022 15:37:06 -0800 X-IronPort-AV: E=Sophos;i="5.88,361,1635231600"; d="scan'208";a="542286966" Received: from nsmdimra-mobl.amr.corp.intel.com (HELO [10.209.96.127]) ([10.209.96.127]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Feb 2022 15:37:05 -0800 Message-ID: Date: Fri, 11 Feb 2022 15:37:03 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Content-Language: en-US To: Rick Edgecombe , 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" , Dave Martin , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com Cc: Yu-cheng Yu References: <20220130211838.8382-1-rick.p.edgecombe@intel.com> <20220130211838.8382-26-rick.p.edgecombe@intel.com> From: Dave Hansen Subject: Re: [PATCH 25/35] x86/cet/shstk: Add user-mode shadow stack support In-Reply-To: <20220130211838.8382-26-rick.p.edgecombe@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/30/22 13:18, Rick Edgecombe wrote: > Add the user shadow stack MSRs to the xsave helpers, so they can be used > to implement the functionality. Do these MSRs ever affect kernel-mode operation? If so, we might need to switch them more aggressively at context-switch time like PKRU. If not, they can continue to be context-switched with the PASID state which does not affect kernel-mode operation. Either way, it would be nice to have some changelog material to that effect.