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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 E0EAEC433B4 for ; Thu, 20 May 2021 20:30:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6A1260FE3 for ; Thu, 20 May 2021 20:30:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238371AbhETUbh (ORCPT ); Thu, 20 May 2021 16:31:37 -0400 Received: from mga11.intel.com ([192.55.52.93]:38712 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236909AbhETUbe (ORCPT ); Thu, 20 May 2021 16:31:34 -0400 IronPort-SDR: GyogX921KpWqy9vIuNuq/+BgJaFP+AJsIkyn+bKMh6F0bFYzRyqZjPG48JLAl61XWnC2ygS7Yp TxfElPzBMWYg== X-IronPort-AV: E=McAfee;i="6200,9189,9990"; a="198244229" X-IronPort-AV: E=Sophos;i="5.82,313,1613462400"; d="scan'208";a="198244229" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 May 2021 13:30:12 -0700 IronPort-SDR: HNZzZilbPBLAs/L6w2j7U600YRh5b3bsng6ThcgvIt0Q6f7rufOuyAwjuHoub+dO0GFAnOmMjS yTNY1BP8P/NA== X-IronPort-AV: E=Sophos;i="5.82,313,1613462400"; d="scan'208";a="543754602" Received: from blydon-mobl.amr.corp.intel.com (HELO [10.209.0.109]) ([10.209.0.109]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 May 2021 13:30:11 -0700 Subject: Re: [RFC v2 27/32] x86/tdx: Exclude Shared bit from __PHYSICAL_MASK To: "Kuppuswamy, Sathyanarayanan" , Peter Zijlstra , Andy Lutomirski , Dan Williams , Tony Luck Cc: Andi Kleen , Kirill Shutemov , Kuppuswamy Sathyanarayanan , Raj Ashok , Sean Christopherson , linux-kernel@vger.kernel.org References: <87b31425b79df3cc44d2bdc6a79d6aa36c42d116.1619458733.git.sathyanarayanan.kuppuswamy@linux.intel.com> <3ae38a0b-0676-1543-7015-39a589b2807a@intel.com> <0df80c0f-e0da-e86e-0ab8-abc58f0da559@linux.intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <0df80c0f-e0da-e86e-0ab8-abc58f0da559@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/20/21 11:48 AM, Kuppuswamy, Sathyanarayanan wrote: >>>   +/* The highest bit of a guest physical address is the "sharing" >>> bit */ >>> +phys_addr_t tdg_shared_mask(void) >>> +{ >>> +    return 1ULL << (td_info.gpa_width - 1); >>> +} >> >> Why not just inline this thing?  Functions don't get any smaller than >> that.  Or does it not get used anywhere else?  Or are you concerned >> about exporting td_info? > > We don't want to export td_info. It has more information additional to > shared mask details. Any reason for suggesting to use inline? My favorite reason is that it eliminates the need for three declarations: 1. An extern for the header 2. A stub for the header 3. The real function in the .c file. An inline removes two places that might get out of sync in some way and eliminates the need to check two implementation sites when grepping. Not in this case, but in general, inlines also result in faster, more compact code since the compiler has more visibility into what the function does at its call sites. Not wanting to export td_info _is_ a reasonable argument, though.