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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80B88C433EF for ; Fri, 11 Feb 2022 23:37:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A6CCF6B0075; Fri, 11 Feb 2022 18:37:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9F6F36B007B; Fri, 11 Feb 2022 18:37:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 895CE6B007D; Fri, 11 Feb 2022 18:37:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0167.hostedemail.com [216.40.44.167]) by kanga.kvack.org (Postfix) with ESMTP id 777C86B0075 for ; Fri, 11 Feb 2022 18:37:09 -0500 (EST) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 372EE96F23 for ; Fri, 11 Feb 2022 23:37:09 +0000 (UTC) X-FDA: 79132112178.18.4460F9D Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by imf13.hostedemail.com (Postfix) with ESMTP id 89A3C20004 for ; Fri, 11 Feb 2022 23:37:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644622628; x=1676158628; h=message-id:date:mime-version:to:cc:references:from: subject:in-reply-to:content-transfer-encoding; bh=n+pCIpoYcPq/hU9tjTp1ZYglJMzSc25WZnIG3BnVpns=; b=Gt1sjeUgiX/su0zqNRQi63UWkguRvV20i643p0VVgxAqthlS/XdcpFd1 4cW2aegKaB2CUvxzcdbDHwW1zn/VckplUNMRb+xiWNEwyEvUQwX5KA8yS FT8tFxHmVSRltbnjhWxFmAZg49l/PlmPm3E+H567XOl8gWVTgl4jqatTT Gqd4LmlUS6jV+K1nHzJOgX7YFSk0R+ymkZyqm5yjC4FqOMVgPLJKwsEtf OKfq1hejTjcRMSHaCTo0nHxrtFo1EjLK1wuUyvtd9xBwzeD6r3JNU9BRR lVhRsqserxaZcId7KUwsJgxPgWQJRkf2BdixMpD++Gq0tCioqi0dL9+ml w==; X-IronPort-AV: E=McAfee;i="6200,9189,10255"; a="249579032" X-IronPort-AV: E=Sophos;i="5.88,361,1635231600"; d="scan'208";a="249579032" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.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 X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 89A3C20004 X-Stat-Signature: ot541bx8nd5g4d7ipd8tua6ecdqdwdj6 Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=Gt1sjeUg; spf=none (imf13.hostedemail.com: domain of dave.hansen@intel.com has no SPF policy when checking 134.134.136.24) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com X-HE-Tag: 1644622628-275855 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 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.