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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 45EBFC43334 for ; Wed, 5 Sep 2018 17:36:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 05A352075E for ; Wed, 5 Sep 2018 17:36:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 05A352075E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727793AbeIEWHX (ORCPT ); Wed, 5 Sep 2018 18:07:23 -0400 Received: from mga18.intel.com ([134.134.136.126]:5939 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726497AbeIEWHX (ORCPT ); Wed, 5 Sep 2018 18:07:23 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Sep 2018 10:36:12 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,334,1531810800"; d="scan'208";a="83311959" Received: from gsharm2-mobl1.amr.corp.intel.com (HELO localhost) ([10.249.37.218]) by fmsmga002.fm.intel.com with ESMTP; 05 Sep 2018 10:36:07 -0700 Date: Wed, 5 Sep 2018 20:36:06 +0300 From: Jarkko Sakkinen To: Sean Christopherson Cc: Andy Shevchenko , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Platform Driver , Dave Hansen , nhorman@redhat.com, npmccallum@redhat.com, linux-sgx@vger.kernel.org, serge.ayoun@intel.com, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , suresh.b.siddha@intel.com, Linux Kernel Mailing List Subject: Re: [PATCH v13 07/13] x86/sgx: Add data structures for tracking the EPC pages Message-ID: <20180905173606.GF11368@linux.intel.com> References: <20180827185507.17087-1-jarkko.sakkinen@linux.intel.com> <20180827185507.17087-8-jarkko.sakkinen@linux.intel.com> <20180904174914.GA5690@linux.intel.com> <20180904181735.GA5820@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180904181735.GA5820@linux.intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 04, 2018 at 11:17:35AM -0700, Sean Christopherson wrote: > On Tue, Sep 04, 2018 at 09:01:15PM +0300, Andy Shevchenko wrote: > > On Tue, Sep 4, 2018 a> +/** > > > > > > > + va = ioremap_cache(addr, size); > > > > > + if (!va) > > > > > + return -ENOMEM; > > > > > > > > I'm not sure this is a right API. Do we operate with memory? Does it > > > > have I/O side effects? > > > > If no, memremap() would be better to use. > > > > > > Preserving __iomem is desirable. There aren't side effects per se, > > > but direct non-enclave accesses to the EPC get abort page semantics so > > > the kernel shouldn't be directly dereferencing a pointer to the EPC. > > > Though by that argument, sgx_epc_bank.va, sgx_epc_addr's return and > > > all ENCLS helpers should be tagged __iomem. > > > > Why? > > Does it related to *any* I/O? > > No, hence my other comment that __private or a new tag altogether may > be more appropriate. The noderef attribute is what we truly care > about. My proposal is that we go with memremap() and use #define __sgx_epc __attribute__((noderef)) It makes sense to check that direct EPC pointers are not passed to functions when they are not supposed to. /Jarkko From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 5 Sep 2018 20:36:06 +0300 From: Jarkko Sakkinen To: Sean Christopherson CC: Andy Shevchenko , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Platform Driver , Dave Hansen , , , , , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , , Linux Kernel Mailing List Subject: Re: [PATCH v13 07/13] x86/sgx: Add data structures for tracking the EPC pages Message-ID: <20180905173606.GF11368@linux.intel.com> References: <20180827185507.17087-1-jarkko.sakkinen@linux.intel.com> <20180827185507.17087-8-jarkko.sakkinen@linux.intel.com> <20180904174914.GA5690@linux.intel.com> <20180904181735.GA5820@linux.intel.com> Content-Type: text/plain; charset="us-ascii" In-Reply-To: <20180904181735.GA5820@linux.intel.com> Return-Path: jarkko.sakkinen@linux.intel.com MIME-Version: 1.0 List-ID: On Tue, Sep 04, 2018 at 11:17:35AM -0700, Sean Christopherson wrote: > On Tue, Sep 04, 2018 at 09:01:15PM +0300, Andy Shevchenko wrote: > > On Tue, Sep 4, 2018 a> +/** > > > > > > > + va = ioremap_cache(addr, size); > > > > > + if (!va) > > > > > + return -ENOMEM; > > > > > > > > I'm not sure this is a right API. Do we operate with memory? Does it > > > > have I/O side effects? > > > > If no, memremap() would be better to use. > > > > > > Preserving __iomem is desirable. There aren't side effects per se, > > > but direct non-enclave accesses to the EPC get abort page semantics so > > > the kernel shouldn't be directly dereferencing a pointer to the EPC. > > > Though by that argument, sgx_epc_bank.va, sgx_epc_addr's return and > > > all ENCLS helpers should be tagged __iomem. > > > > Why? > > Does it related to *any* I/O? > > No, hence my other comment that __private or a new tag altogether may > be more appropriate. The noderef attribute is what we truly care > about. My proposal is that we go with memremap() and use #define __sgx_epc __attribute__((noderef)) It makes sense to check that direct EPC pointers are not passed to functions when they are not supposed to. /Jarkko